Psychology

The Developing Person Through the Life Span

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Christian Pierre. New Friend (front cover), Road to Opportunity (back cover). The luminous colors and figures in New Friend and Road to Opportunity reflect the hope and discovery apparent in all Pierre’s paintings— of adults, animals, plants, landscapes, and children. Pierre has lived in several cultures, under many life circum- stances, but she has said that she could never make herself paint anything depressing. Instead, by combining colors, shapes, and composition in ways that simultaneously reflect fantasy and reality, she illustrates life in ways that allow us to recognize truths that we may not have noticed before. Development is about connections— between one age and another, between one group and another, or even between one living creature and another. Joy and affection for every developing person, of whatever age or status, combine as the theme of this text.

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Bronx Community College

City University of New York

The Developing Person Through the Life Span

Kathleen Stassen Berger

SEVENTH EDITION

WORTH PUBLISHERS

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Publisher: Catherine Woods

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K athleen Stassen Berger received her undergraduate education at Stanford University and Radcliffe College, earned an M.A.T. from Harvard University and an M.S. and Ph.D from Yeshiva University.

Her broad experience as an educator includes directing a preschool, teach- ing philosophy and humanities at the United Nations International School, teaching child and adolescent development to graduate students at Fordham University, teaching undergraduates at Montclair State University in New Jersey and at Quinnipiac University in Connecticut, as well as inmates earn- ing paralegal degrees at Sing Sing Prison.

For the past 35 years, Berger has taught at Bronx Community College of the City University of New York. She has taught introduction to psychology, child and adolescent development, adulthood and aging, social psychology, abnormal psychology, and human motivation. Her students—who come from many ethnic, economic, and educational backgrounds and who have a wide range of interests—consistently honor her with the highest teaching evaluations. Her own four children attended New York City public schools, one reason that she was elected as president of Community School Board in District Two.

Berger is also the author of The Developing Person Through Childhood and Adolescence. Her developmental texts are currently being used at nearly 700 colleges and universities worldwide and are available in Spanish, French, Italian, and Portuguese as well as English. Her research interests include adolescent identity, sibling relationships, and bullying, and she has con- tributed articles on developmental topics to the Wiley Encyclopedia of Psychology. Berger’s interest in college education is manifest in articles pub- lished by the American Association for Higher Education and the National Education Association for Higher Education. She continues to teach and learn with every semester and every edition of her books.

A B O U T T H E AU T H O R

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B R I E F C O N T E N T S

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Preface xvii

PART I The Beginnings 1 Chapter 1 Introduction 3

Chapter 2 Theories of Development 33 Chapter 3 Heredity and Environment 61

Chapter 4 Prenatal Development and Birth 91

PART II The First Two Years 123 Chapter 5 The First Two Years: Biosocial Development 125 Chapter 6 The First Two Years: Cognitive Development 155

Chapter 7 The First Two Years: Psychosocial Development 179

PART III The Play Years 205 Chapter 8 The Play Years: Biosocial Development 207 Chapter 9 The Play Years: Cognitive Development 231

Chapter 10 The Play Years: Psychosocial Development 255

PART IV The School Years 281 Chapter 11 The School Years: Biosocial Development 283

Chapter 12 The School Years: Cognitive Development 307 Chapter 13 The School Years: Psychosocial Development 333

PART V Adolescence 361 Chapter 14 Adolescence: Biosocial Development 363 Chapter 15 Adolescence: Cognitive Development 391

Chapter 16 Adolescence: Psychosocial Development 415

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PART VI Emerging Adulthood 445 Chapter 17 Emerging Adulthood: Biosocial Development 447 Chapter 18 Emerging Adulthood: Cognitive Development 471

Chapter 19 Emerging Adulthood: Psychosocial Development 499

PART VII Adulthood 525 Chapter 20 Adulthood: Biosocial Development 527 Chapter 21 Adulthood: Cognitive Development 555

Chapter 22 Adulthood: Psychosocial Development 577

PART VIII Late Adulthood 611 Chapter 23 Late Adulthood: Biosocial Development 613 Chapter 24 Late Adulthood: Cognitive Development 649

Chapter 25 Late Adulthood: Psychosocial Development 679 Epilogue Death and Dying Ep-1

Appendix A Supplemental Charts, Graphs, and Tables A-1 Appendix B More About Research Methods B-1

Appendix C Suggestions for Research Assignments C-1

Glossary G-1

References R-1

Name Index NI-1

Subject Index SI-1

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Preface xvii

PART I

The Beginnings 1

Chapter 1 Introduction 3

Defining Development 3 Science 3 Diversity 4 Connections Between Change and Time 4

Five Characteristics of Development 7 Multidirectional 7 Multicontextual 9 Multicultural 10 ISSUES AND APPLICATIONS: “My Name Wasn’t

Mary” 12 Multidisciplinary 13 Plasticity 15 A CASE TO STUDY: My Nephew David 15

Developmental Study as a Science 16 Steps of the Scientific Method 16 Ways to Test Hypotheses 17 Studying Change over Time 21

Cautions from Science 25 Correlation and Causation 25 Quantity and Quality 26 Ethics in Research 27

Chapter 2 Theories of Development 33

What Theories Do 33

Grand Theories 34 Psychoanalytic Theory 35 Behaviorism 38 THINKING LIKE A SCIENTIST: What’s a Mother For? 40 Cognitive Theory 43

Emergent Theories 46 Sociocultural Theory 46 Epigenetic Theory 49 IN PERSON: My Beautiful, Hairless

Babies 53

What Theories Contribute 54 The Nature–Nurture Controversy 55 No Answers Yet 57

Chapter 3 Heredity and Environment 61

The Genetic Code 61 What Genes Are 61 The Beginnings of Life 63 ISSUES AND APPLICATIONS: Too Many Boys? 65

From One Cell to Many 66 New Cells, New Functions 66 Gene–Gene Interactions 67 More Complications 68 IN PERSON: “I Am Not Happy With Me” 72

From Genotype to Phenotype 73 Addiction 74 Visual Acuity 75 Practical Applications 77

Chromosomal and Genetic Abnormalities 79 Not Exactly 46 Chromosomes 79 Dominant-Gene Disorders 81 Recessive-Gene Disorders 84 Genetic Counseling and Testing 84 THINKING LIKE A SCIENTIST: Who Decides? 85

C O N T E N T S

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Ethnic Variations 141 IN PERSON: The Normal Berger Babies 142

Public Health Measures 143 Immunization 144 Sudden Infant Death Syndrome 146 ISSUES AND APPLICATIONS: Back to Sleep 148 Nutrition 148

Chapter 6 The First Two Years: Cognitive Development 155

Sensorimotor Intelligence 155 Stages One and Two: Primary Circular Reactions 156 Stages Three and Four: Secondary Circular Reactions 157 THINKING LIKE A SCIENTIST: Object Permanence

Revisited 158 Stages Five and Six: Tertiary Circular

Reactions 159 Piaget and Research Methods 160

Information Processing 161 Affordances 162 Memory 165

Language:What Develops in the First Two Years? 167 The Universal Sequence 168 The Naming Explosion 169 Theories of Language Learning 171

Chapter 7 The First Two Years: Psychosocial Development 179

A CASE TO STUDY: Parents on Autopilot 179

Emotional Development 180 Specific Emotions 180 Self-Awareness 182

Theories About Infant Psychosocial Development 183

Psychoanalytic Theory 183 Behaviorism 184 Cognitive Theory 184 Epigenetic Theory 185 Sociocultural Theory 188 A CASE TO STUDY: “Let’s Go to Grandma’s” 189

The Development of Social Bonds 191 Synchrony 191 THINKING LIKE A SCIENTIST: The Still-Face

Technique 192 Attachment 192 Social Referencing 196 Infant Day Care 197

Conclusions in Theory and Practice 199

Chapter 4 Prenatal Development and Birth 91

From Zygote to Newborn 91 Germinal: The First 14 Days 91 Embryo: From the Third Through the Eighth Week 93 Fetus: From the Ninth Week Until Birth 94

Risk Reduction 97 Determining Risk 98 Protective Measures 101 THINKING LIKE A SCIENTIST: On Punishing Pregnant

Drinkers 102 Benefits of Prenatal Care 104 A CASE TO STUDY: What Do People Live to Do? 106 A CASE TO STUDY: What Does That Say About Me? 108

The Birth Process 108 The Newborn’s First Minutes 109 Variations 110 Birth Complications 112 Social Support 116 A CASE TO STUDY: “You’d Throw Him in a Dumpster” 118 Postpartum Depression 118

PART II

The First Two Years 123

Chapter 5 The First Two Years: Biosocial Development 125

Body Changes 125 Body Size 125 Sleep 127

Brain Development 129 Connections in the Brain 129 Necessary and Possible Experiences 132 Implications for Caregivers 133 THINKING LIKE A SCIENTIST: Plasticity and

Orphans 134

Senses and Motor Skills 136 Sensation and Perception 136 Motor Skills 138

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CONTENTS xi

PART III

The Play Years 205

Chapter 8 The Play Years: Biosocial Development 207

Body Changes 207 Growth Patterns 207 Eating Habits 208

Brain Development 210 Speed of Thought 210 Connecting the Brain’s Hemispheres 210 Planning and Analyzing 212 Emotions and the Brain 213 Motor Skills 215

Injuries and Abuse 218 Avoidable Injury 219 IN PERSON: “My Baby Swallowed Poison” 221 Child Maltreatment 222 A CASE TO STUDY: A Series of Suspicious Events 224

Chapter 9 The Play Years: Cognitive Development 231

Piaget and Vygotsky 231 Piaget: Preoperational Thinking 231 Vygotsky: Social Learning 234

Children’s Theories 236 Theory-Theory 236 Theory of Mind 238

Language 240 Vocabulary 240 IN PERSON: “Mommy the Brat” 241 Grammar 242 Learning Two Languages 243

Early-Childhood Education 245 Child-Centered Programs 246 Teacher-Directed Programs 248 Intervention Programs 249 Costs and Benefits 251

Chapter 10 The Play Years: Psychosocial Development 255

Emotional Development 255 Initiative Versus Guilt 255 Psychopathology 258 Empathy and Antipathy 259

Parents 264 Parenting Style 264 ISSUES AND APPLICATIONS: Planning Punishment 267 The Challenge of Media 268

Becoming Boys and Girls 271 Theories of Gender Differences 271 IN PERSON: Berger and Freud 273 Gender and Destiny 276

PART IV

The School Years 281

Chapter 11 The School Years: Biosocial Development 283

A Healthy Time 283 Size and Shape 284 Physical Activity 286 Chronic Illness 288

Brain Development 290 Advances in Brain Functioning 290 Measuring the Mind 291

Children with Special Needs 295 A CASE TO STUDY: Billy: Dynamo or Dynamite? 295 Developmental Psychopathology 296 THINKING LIKE A SCIENTIST: Overdosing and

Underdosing 298 Educating Children with Special Needs 301

Chapter 12 The School Years: Cognitive Development 307

Building on Theory 307 Piaget and School-Age Children 307 Vygotsky and School-Age Children 309 Information Processing 310

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The Transformations of Puberty 371 Growing Bigger and Stronger 371 Sexual Maturation 373 Brain Development 375 A CASE TO STUDY: What Were You Thinking? 375 ISSUES AND APPLICATIONS: Calculus at 8 A.M.? 379

Possible Problems 380 Sex Too Soon 380 Drug Use and Abuse 383 Learning from Experience 387

Chapter 15 Adolescence: Cognitive Development 391

Adolescent Thinking 391 Egocentrism 391 IN PERSON: Bethany and Jim 394 Formal Operational Thought 395 Intuitive, Emotional Thought 397 Better Thinking 400 THINKING LIKE A SCIENTIST: Teenage Religion 400

Teaching and Learning 401 Middle School: Less Learning 402 Technology and Cognition 404 Transition and Translations 406 Teaching and Learning in High School 407 ISSUES AND APPLICATIONS: Diversity of Nation,

Gender, and Income 407

Chapter 16 Adolescence: Psychosocial Development 415

Identity 415 Not Yet Achieved 416 Four Arenas of Identity Achievement 416

Relationships 419 Adults and Teenagers 419 Peer Support 422 IN PERSON: The Berger Daughters

Seek Peer Approval 423

Sexuality 427 Before Committed Partnership 427 Learning About Sex 429 Sexual Behavior 432

Sadness and Anger 433 Depression 433 Suicide 434 A CASE TO STUDY: He Kept His Worries to Himself 437 More Destructiveness 437 THINKING LIKE A SCIENTIST: A Feminist

Looks at the Data 439

Language 314 Vocabulary and Pragmatics 314 Second-Language Learning 315 ISSUES AND APPLICATIONS: SES and Language

Learning 317

Teaching and Learning 317 Curriculum 318 The Outcome 321 THINKING LIKE A SCIENTIST: International Achievement

Tests 321 Education Wars and Assumptions 323 A CASE TO STUDY: When Did You Learn Tsunami? 326 Culture and Education 328

Chapter 13 The School Years: Psychosocial Development 333

The Peer Group 333 The Culture of Children 334 Children’s Moral Codes 335 Social Acceptance 337 Bullies and Victims 339

Families and Children 342 Shared and Nonshared Environment 343 THINKING LIKE A SCIENTIST: “I Always Dressed One

in Blue Stuff . . . “ 343 Families Function and Dysfunction 344 Family Trouble 348

The Nature of the Child 351 Psychoanalytic Theory 351 Self-Concept 352 Coping and Overcoming 353

PART V

Adolescence 361

Chapter 14 Adolescence: Biosocial Development 363

Puberty Begins 364 Hormones 364 When Will Puberty Start? 366 Too Early, Too Late 369 Nutrition 370

xii CONTENTS

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PART VI

Emerging Adulthood 445

Chapter 17 Emerging Adulthood: Biosocial Development 447

Growth, Strength, and Health 447 Ages and Stages 447 Strong and Attractive Bodies 449 Bodies Designed for Health 450 ISSUES AND APPLICATIONS: Who Should

Get the Bird Flu Shot? 451 Sexual Activity 453

Habits and Risks 456 Exercise 456 Eating Well 457 A CASE TO STUDY: “Too Thin, As If That’s Possible” 461 Taking Risks 462 ISSUES AND APPLICATIONS: What’s Wrong with the

Men? 464

Chapter 18 Emerging Adulthood: Cognitive Development 471

Postformal Thought 472 The Practical and the Personal: A Fifth Stage? 472 Cognitive Flexibility 475 THINKING LIKE A SCIENTIST: Reducing Stereotype

Threat 479 Dialectical Thought 480

Morals and Religion 483 Which Era? What Place? 483 ISSUES AND APPLICATIONS: Clear Guidelines for

Cheaters 485 Measuring Moral Growth 486 Stages of Faith 486 IN PERSON: Faith and Tolerance 488

Cognitive Growth and Higher Education 488 The Effects of College 489 Changes in the College

Context 490 Evaluating the Changes 494

Chapter 19 Emerging Adulthood: Psychosocial Devleopment 499

Identity Achieved 499 Ethnic Identity 500 Vocational Identity 502

Intimacy 503 Friendship 504 Romance and Relationships 507 IN PERSON: Changing Expectations

About Marriage 507 What Makes Relationships Work 511 ISSUES AND APPLICATIONS: Domestic Violence 513 Family Connections 513

Emotional Development 516 Well-Being 516 Psychopathology 518 Continuity and Discontinuity 520

PART VII

Adulthood 525

Chapter 20 Adulthood: Biosocial Development 527

The Aging Process 528 Senescence 528 The Sexual-Reproductive System 532

The Impact of Poor Health Habits 536 Tobacco and Alcohol Use 537 Lack of Exercise 539 Overeating 540 Preventive Medicine 543 ISSUES AND APPLICATIONS: Responding to Stress 544

Measuring Health 545 Mortality and Morbidity 545 Disability and Vitality 546 ISSUES AND APPLICATIONS: QALYs and DALYs 546

Variations in Aging 548 Gender Differences 548 Socioeconomic Status 549 Conclusion 550

CONTENTS xiii

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xiv CONTENTS

The Demographic Shift 616 Dependents and Independence 618

Senescence 620 Aging and Disease 620 Selective Optimization with Compensation 623 Health Habits 624 ISSUES AND APPLICATIONS: Getting from Place to

Place 626 The Brain 628 Physical Appearance 629 Dulling of the Senses 630 Compression of Morbidity 633

Theories of Aging 635 Wear and Tear 635 Genetic Adaptation 636 Cellular Aging 639 THINKING LIKE A SCIENTIST: Can the

Aging Process Be Stopped? 641

The Centenarians 643 Other Places, Other Stories 643 The Truth About Life After 100 644

Chapter 24 Late Adulthood: Cognitive Development 649

The Usual: Information-Processing After Age 65 649 Sensing and Perceiving 650 A CASE TO STUDY: “That Aide Was Very Rude” 650 Memory 651 THINKING LIKE A SCIENTIST: John, Paul, Ringo, and . . . 653 Control Processes 654 THINKING LIKE A SCIENTIST: Neuroscience and Brain

Activity 656 Staying Healthy and Alert 659 Ageism 660

The Impaired: Dementia 662 Alzheimer’s Disease 663 Many Strokes 665 Subcortical Dementias 666 Reversible Dementia 667 A CASE TO STUDY: Is It Dementia or Drug Addiction? 668 Prevention and Treatment 669

The Optimal: New Cognitive Development 670 Aesthetic Sense and Creativity 671 The Life Review 672 Wisdom 673

Chapter 21 Adulthood: Cognitive Development 555

What Is Intelligence? 556 Research on Age and Intelligence 556 A CASE TO STUDY: “At Very Different Levels” 560 Components of Intelligence: Many and Varied 561 Diversity and Intelligence 564 A CASE TO STUDY: Jenny: ”Men Come and Go” 566

Selective Gains and Losses 567 Optimization with Compensation 567 Expert Cognition 569 Expertise and Age 571 IN PERSON: An Experienced Parent 574

Chapter 22 Adulthood: Psychosocial Development 577

Ages and Stages 578 A CASE TO STUDY: She “Began to Make a New Life on Her

Own” 579 The Social Clock 579 Personality Throughout Adulthood 581

Intimacy 585 Friends 585 Family Bonds 587 IN PERSON: Childhood Echoes 590 Marriage 590 Homosexual Partners 592 Divorce 593

Generativity 596 Caregiving 596 Employment 600 A CASE TO STUDY: Linda: “A Much Sturdier Self” 607

PART VIII

Late Adulthood 611

Chapter 23 Late Adulthood: Biosocial Development 613

Prejudice and Predictions 615 Ageism 615 Gerontology 616

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CONTENTS xv

Chapter 25 Late Adulthood: Psychosocial Development 679

Theories of Late Adulthood 680 Self Theories 680 ISSUES AND APPLICATIONS: Thinking Positively 683 Stratification Theories 684 A CASE TO STUDY: Doing Just Fine? 689 Dynamic Theories 689

Coping with Retirement 691 Deciding When to Retire 691 Retirement and Marriage 691 Aging in Place 692 Continuing Education 693 Volunteer Work 693 Religious Involvement 695 Political Activism 695

Friends and Relatives 696 Long-Term Marriages 697 Losing a Spouse 698 Relationships with Younger Generations 700 Friendship 703

The Frail Elderly 706 Activities of Daily Life 706 ISSUES AND APPLICATIONS: Buffers Between Fragile and

Frail 707 Caring for the Frail Elderly 708

Epilogue Death and Dying Ep-1

Death and Hope Ep-1 Death Throughout the Life Span Ep-2 Many Religions, Many Cultures Ep-6

Dying and Acceptance Ep-10 Attending to the Needs of the Dying Ep-10 A CASE TO STUDY: “Ask My Son and My Husband” Ep-11 Choices and Controversies Ep-13 ISSUES AND APPLICATIONS: Let Terry Schiavo

Live/Die/Live/Die Ep-17

Bereavement Ep-18 Normal Grief Ep-18 IN PERSON: Blaming Martin, Hitler, and Me Ep-19 Complicated Grief Ep-20 Diversity of Reactions Ep-22

Appendix A Supplemental Charts, Graphs, and Tables A-1

Appendix B More About Research Methods B-1

Appendix C Suggestions for Research Assignments C-1

Glossary G-1

References R-1

Name Index NI-1

Subject Index SI-1

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Preface

Each year, each day, and even each hour is a gift, to be filled with joy andwork. At least that is how it seems to me. I write for the tens of thousandsof students (in 12 nations and five languages) who will read this book. I hope each of you sees your life as a gift and finds joy and work in this book, as you come to understand and appreciate development.

Change and continuity are the dynamic themes of development. Both are evident in my life and in this book.

I recently sold our house and moved into a new apartment near the Hudson River, beside which I walk almost every day; many gifts there. I watch my children grow, and I realize that their lives and this text are intertwined.

To be specific, my interest in development began in earnest when our first two children (Bethany and Rachel) were infants; as a young professor I often told anecdotes of their early days. Some of those stories appear in this book. A few years later, our third baby (Elissa) cried and needed a walk; that led to an encounter that led to a book contract. Our fourth child (Sarah) was conceived because this text was widely adopted. She is the only one whose photographs we could afford to have taken professionally, and only they made it into this text.

Now all four are adults. Their recent experiences showed me the need for new chapters in this seventh edition, a trio on emerging adulthood. The deaths of my parents and my husband over the past seven years have made me think more deeply about dying; the Epilogue is twice as long as before, with new insights not present in previous editions.

Changes come from the wider community of social scientists as well. Global- ization, neuroscience, dynamic systems, and genetic analysis have all provided new insights. This book now has Research Design features, data, and many discussions of the similarities and differences among developing persons worldwide. Further, the integration of mind and body is much better understood, and you will find specifics about the brain and about heredity at every stage of life.

Teaching and writing remain my life’s work and passion. I strive to make this text challenging and accessible to every student, remembering that my students were my original reason to write a developmental text. They deserved a text that respected their intellect and experiences, without making development seem dull or obscure. Overall, I believe that a better world is possible because today’s stu- dents will become tomorrow’s wise leaders; this book is my contribution—I hope you see it as a gift—toward that goal.

To learn more about the specifics of this text, including the material that is new to this edition, read on. Or you can turn to the beginning of Chapter 1, and begin your study.

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xviii PREFACE

New Material Every year brings new concepts and research. The best of these are integrated into the text, including hundreds of new references on many topics—among them mirror neurons, the use of prescription medication in young children, autistic spectrum disorders, attachment over the life span, high-stakes testing, brain changes in midlife, and public policy about dying.

Revised Chapters on Adolescence and Emerging Adulthood I’ve been sensitive to current research throughout the book, but I’ve been partic- ularly impressed with the magnitude of the changes that are happening in our understanding of adolescence and the years now referred to as emerging adult- hood. As a result, I have spent a lot of time reading and rewriting the six chapters covering the period from age 12 to age 25. Highlights include new discoveries about the adolescent brain (e.g., the prefrontal cortex is not fully mature until the early 20s), the onset of puberty even before the teen years, and the dramatic shift in emerging adulthood—once a time for settling down, but now a time for explor- ing, learning, and risk taking.

It no longer makes sense to divide adulthood into “early,” “middle,” and “late,” as the previous editions did. Now three chapters (17, 18, and 19) cover emerging adulthood (ages 18 to 25) and the next three chapters (20, 21, and 22) cover adult- hood (ages 25 to 65). This reorganization reflects the fact that the major events of those years, including ongoing senescence, expertise, intimate partnership, and parenthood may occur at every age during those 40 years, depending on the spe- cific choices and circumstances of each developing person. The work and love— that is, vocation and family—of adulthood are no longer split between two periods. This new view of adult life is a dramatic example of the way the scientific study of development shifts as new research and theories appear.

Cognition on Display Shared facials, pedicures, nail painting, eyebrow waxing, and other such beauty rituals are bonding experiences for teenage girls. Parents may blame teen magazines or the superficiality of the culture in general, but their daughters’ ego- centric thinking may be the true origin of these activities.

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Extensive Coverage of Brain Development Beyond organizational changes, every page of this text reflects new research and theory. Brain development is the most obvious example: Every trio of chapters includes a section on the brain. A sampling of this new material is listed below.

Patterns of developmental growth, pp. 7–8 Mirror neurons, p. 14 Brain development and the epigenetic model of development, pp. 50–51 From one cell to many: Genetic development, pp. 66–67 Genotypes and phenotypes, pp. 73–74 Down syndrome and brain development, pp. 79–80 Fetal brain development, pp. 93–96 Prenatal growth of the brain, p. 97 Teratogens and brain development, pp. 97–99 Brain development during infancy and toddlerhood, pp. 129–136 Sensation, perception, and the brain, pp. 136–139 Brain maturation within the motor cortex, p. 140 Effects of nutrition on the brain, pp. 148–150 Some techniques used by neuroscientists to understand brain function, p. 160 Information processing, p. 161 Measuring infant temperament, pp. 186–188 Synchrony, p. 192 Biosocial development and the brain during early childhood, pp. 207–214 Memory and brain systems, pp. 213–214 Cognitive development and brain maturation during early childhood, pp. 238–239 Emotional regulation during the play years, pp. 258–259 Epigenetic theory, p. 276 The school years: Brain development, pp. 290–303 The school years: Memory formation, p. 311 Hormones in adolescence, pp. 364–365 Brain development in adolescence, pp. 375–380 Drug use in adolescence, pp. 386–387 Cognitive development in adolescence: “Dual-process model” of adolescent

thought, p. 398 Information-processing approach: How brain encodes, stores, and retrieves

information, p. 473 The aging brain, pp. 530–532 Fluid and crystallized intelligence, pp. 561–562 Brain effects on intelligence, p. 564

PREFACE xix

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Front Front

Back Back

(a) (b)

The Prefrontal Cortex Matures These are composite scans of normal brains of (a) children and adolescents and (b) adolescents and adults. The red areas indicate both an increase in brain size and a decrease in gray matter (cerebral cortex). The red areas in (b) are larger than in (a) and are concentrated in the frontal area of the brain, which is associated with complex cognitive processes. The growth of brain areas as their gray matter decreases is believed to reflect an increase in white matter, which consists of myelin—the axon coating that makes the brain more efficient.

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The brain in late adulthood, pp. 628–629 Thinking Like a Scientist: Neuroscience and Brain Activity, pp. 656–657 Brain slowdown: Primary and secondary aging, pp. 658–659 Dementia, pp. 662–670 Brain death, p. Ep-3

New Research Design Feature A new element appears in this edition, to highlight the science of development. Each chapter includes two or more Research Design boxes. Each is keyed to a study cited in the adjacent text and explains more about the participants and methods of that study. Students are encouraged to read the original studies, which also reveal the many ways—via statistics, hypotheses, and research findings—by which scientists move beyond their original assumptions.

Content Changes to the Seventh Edition Life-span development, like all sciences, builds on past learning. Many facts and concepts must be restated in every edition of a textbook—stages and ages, norms and variations, dangers and diversities, classic theories and fascinating applications. However, the study of development is continually changed by discoveries and innovations, so no page in this seventh edition is exactly what it was in the sixth edition, much less the first. Highlights of this updating appear below.

Part I: The Beginnings 1. Introduction

■ New subsection “Defining Development” discusses the three crucial elements of the science of human development.

■ Increased focus on dynamic systems theory. ■ Issues and Applications: “My Name Wasn’t Mary,” about the childhood of

poet Maya Angelou. ■ New coverage of mirror neurons. ■ New discussion of quantitative vs. qualitative research. ■ New discussion of protection of research participants.

2. Theories of Development ■ Expanded, updated coverage of epigenetic theory. ■ Extensively revised discussion of selective adaptation with new examples. ■ New subsection on nature–nurture interaction.

3. Heredity and Environment ■ Expanded discussion of identical twins. ■ New coverage of cloning. ■ New coverage of infertility and assisted reproductive technology, including

In Person: “I Am Not Happy with Me,” about in vitro fertilization. ■ New subsection “Visual Acuity,” on genetic and cultural factors in

nearsightedness. ■ New coverage of type 2 diabetes epidemic.

4. Prenatal Development and Birth ■ Updated data on preterm births. ■ New subsection “Protective Measures,” on reducing the risks of teratogens. ■ New subsection “Benefits of Prenatal Care,” focusing on diagnostic testing. ■ Expanded and updated coverage of low birthweight. ■ New: A Case to Study: “What Does That Say About Me?”

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Research Design Scientists: Six researchers, sponsored by the RAND Corporation.

Publication: Pediatrics (2006).This study was also reported in many news stories.

Participants:Total of 1,461 U.S. teenagers, randomly selected to be rep- resentative of all U.S. teens.

Design:Teenagers were interviewed by phone three times over three years and asked which of 16 popular music groups they listened to. Coders rated whether songs contained sexually degrading lyrics. Some participants refused to answer questions about sex, but responses of 938 who were virgins when the study began were analyzed.

Major conclusion: Listening to degrad- ing music about sex, but not other teen music about sex, encourages teenagers to have sexual intercourse.

Comment:This is a correlational study. The longitudinal sequence (music, then intercourse) prompted the conclusions, but others disagree about the relation- ship between the variables.

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Part II: The First Two Years 5. The First Two Years: Biosocial Development

■ New coverage of co-sleeping ■ New subsection “Implications for Caregivers,” covering self-righting, plasticity,

and sensitive periods in brain development. ■ Expanded coverage of infant reflexes, walking, immunization, and

breast-feeding.

6. The First Two Years: Cognitive Development ■ New subsection on recent research on early affordances. ■ New coverage of implicit and explicit memory. ■ Updated coverage of the hybrid perspective on language development.

7. The First Two Years: Psychosocial Development ■ Updated and expanded coverage of temperament—and what it means for

caregivers. ■ Expanded coverage of sociocultural theory, with new material on ethnotheories

(including A Case to Study: “Let’s Go to Grandma’s,” on the difference be- tween North American and Mayan parents’ ethnotheories) and on proximal and distal parenting practices.

■ Expanded coverage of synchrony, including Thinking Like a Scientist: The Still-Face Technique, on infants’ responses to parental “still face.”

■ Updated coverage of attachment. ■ Updated and expanded coverage of infant day care.

Part III: The Play Years 8. The Play Years: Biosocial Development

■ New material on maturation of the prefrontal cortex. ■ New section “Emotions and the Brain,” on the limbic system and on the

effects of stress. ■ Updated and reorganized coverage of injuries and abuse, including In Person:

“My Baby Swallowed Poison,” on strategies for injury prevention.

A Beneficial Beginning These new mothers in a maternity ward in Manila are providing their babies with kangaroo care.

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My Youngest at 8 Months When I look at this photo of Sarah, I see evidence of Mrs. Todd’s devotion. Sarah’s hair is washed and carefully brushed, her jumper and blouse are clean and pressed, and the carpet and stepstool are perfect equipment for standing practice. Sarah’s legs—chubby and far apart— indicate that she is not about to walk early; but, given all these signs of Mrs. Todd’s attention to caregiving, it is not surprising, in hindsight, that my fourth daughter was my earliest walker.

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9. The Play Years: Cognitive Development ■ New subsection on theory-theory. ■ Expanded and updated coverage of vocabulary development and bilingualism,

including new subsection “Constant Change.” ■ Expanded coverage of preschools, including Montessori, Reggio Emilia, and

Head Start.

10. The Play Years: Psychosocial Development ■ New subsection “Intrinsic Motivation.” ■ Expanded discussions of empathy and aggression. ■ New box on punishment. ■ Expanded, updated coverage of the media and its effects.

Part IV: The School Years 11. The School Years: Biosocial Development

■ Revised, expanded, and updated discussion of overweight children. ■ New section on physical activity, covering benefits and hazards, neighborhood

play, exercise in school, and clubs and leagues. ■ Expanded coverage of chronic illness and asthma. ■ New subsection on gifted children and mentally retarded children. ■ New box on prescribing psychoactive drugs for children. ■ New subsection “Autistic Spectrum Disorders.”

12. The School Years: Cognitive Development ■ Updated, expanded coverage of education, particularly bilingual education,

curriculum (internationally and in the United States, including the No Child Left Behind Act), and math instruction in the United States, as well as new subsections on education in Japan and on education and culture.

■ New boxes: Issues and Applications: SES and Language Learning; Thinking Like a Scientist: International Achievement Tests; and A Case to Study: Where Did You Learn Tsunami?

13. The School Years: Psychosocial Development ■ Extensively revised and updated section on the peer group, with new focus

on the culture of children, children’s moral codes, and social acceptance.

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He’s Listening With tilted head and pink tutu, this girl exemplifies two of the best characteristics often found in young children: empathy and self-confidence. Responding to her personality and concern, the distressed boy may well decide to rejoin the group. ELL

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■ New box Thinking Like a Scientist: “I Always Dressed One in Blue Stuff,” on parental effects on children’s development.

■ Expanded, updated material on effects of family income.

Part V: Adolescence 14. Adolescence: Biosocial Development

■ New box: A Case to Study: What Were You Thinking? on physical risk taking. ■ New section on brain development, focusing on recent brain research, the

relationship between brain and behavior, and puberty and biorhythms. ■ New box Issues and Applications: Calculus at 8 A.M.? ■ Updated discussions of teenage pregnancy and STIs. ■ Reorganized, updated discussion of drug use and abuse.

15. Adolescence: Cognitive Development ■ New section on the possibilities and problems related to adolescent use of

the Internet and other new technologies. ■ New major section “Teaching and Learning,” with new subsections on middle

schools, the transition from middle school to high school, including high-stakes testing, dropouts, school violence, and new approaches.

■ New Issues and Applications: Diversity of Nation, Gender, and Income, on an international study of problem-solving abilities of adolescents.

16. Adolescence: Psychosocial Development ■ New section “Technology for Everyone,” on technology and identity exploration ■ New subsections on religious identity and vocational identity. ■ Updated and expanded material on sexual/gender identity and political/

ethnic identity. ■ Updated and expanded material on parent–adolescent relationships. ■ New subsection “Cliques and Crowds” (including new In Person: The Berger

Daughters Seek Peer Approval). ■ New subsection on peer selection and peer facilitation. ■ New major section “Sexual Activity.” ■ Updated material on suicide and parasuicide, including A Case to Study:

He Kept His Worries to Himself. ■ Updated material on lawbreaking and delinquency, including Thinking Like

a Scientist: A Feminist Looks at the Data.

Part VI: Emerging Adulthood 17. Emerging Adulthood: Biosocial Development

■ New subsection “Looking Good” on concern with attractiveness. ■ Expanded discussions of sexual activity and problems with sex, including

new material on STIs and unwanted pregnancies. ■ Issues and Applications: Who Gets the Bird Flu Shot? on the question of

which age group should be immunized first against bird flu. ■ New major section “Health Habits,” with subsections on exercise and nutrition. ■ New major section “Taking Risks,” with new material on social protection,

time perspective, and social norms.

18. Emerging Adulthood: Cognitive Development ■ New material on cognitive flexibility. ■ Revised and updated material on morals and religion. ■ Revised and updated material on diversity among college students and on

graduates and dropouts.

PREFACE xxiii

Disabled but Vital Therapists find that the most serious consequence of losing a limb is losing the will to live. This young man not only learned to cope with crutches after losing a leg but also regained his spirit: He completed the 26.2-mile New York City marathon.

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19. Emerging Adulthood: Psychosocial Development ■ Updated material on the dimensions of love. ■ New section “Family Connections,” on continuing family dependence. ■ New section “Emotional Development,” including sections on well-being,

psychopathology (substance abuse, mood disorders, anxiety disorders, schizophrenia), and continuity and discontinuity.

Part VII: Adulthood 20. Adulthood: Biosocial Development

■ Updated and revised discussion of the sexual-reproductive system. ■ New material on nutrition and obesity. ■ New section “Preventive Medicine.” ■ New material on health and ethnicity.

21. Adulthood: Cognitive Development ■ New A Case to Study: “At Very Different Levels,” on individual variations

over time. ■ Revised and updated material on age and culture. ■ New material on automatic expert cognition. ■ New and updated material on coping with stress, including In Person:

An Experienced Parent.

22. Adulthood: Psychosocial Development ■ New section “Friends.” ■ Revised and updated material on marriage. including new material on

homogamy and marital equity. ■ New section “Caregiving,” including new, revised, and updated material on

parenthood and on caring for aging parents. ■ Extensively revised and updated section on employment.

Part VIII: Late Adulthood 23. Late Adulthood: Biosocial Development

■ New Issues and Applications: Getting from Place to Place, on the importance of maintaining mobility.

■ Updated and revised section on genetic aging, including discussions of average and maximum life expectancy and selective adaptation.

■ New box on theories of aging and attempts to prolong life.

xxiv PREFACE

Thumbs Up! These graduates in Long Beach, California, are joyful that they have reached a benchmark. Ideally, their diplomas will earn them not only better jobs but also an intellectual perspective that will help them all their lives. LOU

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24. Late Adulthood: Cognitive Development ■ New A Case to Study: “That Aide Was Very Rude,” on sensory declines. ■ Revised and updated section on control processes. ■ Revised and updated section on secondary aging. ■ New A Case to Study: Is It Dementia or Drug Addiction?,

on problems of overmedication and drug abuse. ■ New section on prevention and treatment of dementia.

25. Late Adulthood: Psychosocial Development ■ New Issues and Applications: Thinking Positively. ■ New section on recent work and retirement trends and issues.

Epilogue: Death and Dying ■ Greatly expanded, revised, and reorganized throughout. ■ New main section “Death and Hope,” with new material on

death throughout the life span, death and religion, acceptance of dying, and choosing death (including new Issues and Applications: Let Terri Schiavo Live/Die/Live/Die).

■ New subsection “Seeking Blame and Meaning,” including In Person: Blaming Martin, Hitler and Me, on a husband’s death.

■ Revised and expanded material on diversity of reactions to bereavement.

Ongoing Features Many characteristics of this book have been acclaimed since the first edition and have been retained in this revision.

Writing That Communicates the Excitement and Challenge of the Field An overview of the science of human development should be lively, just as real people are. Each sentence conveys tone as well as content. Chapter-opening vignettes bring student readers into the immediacy of development. Examples and explanations abound, helping students make the connections among theory, research, and their own experiences.

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Determined to Vote Older voters tend to have stronger political opinions, more party loyalty, and higher voting rates than younger adults. This Punjabi woman takes an active interest in politics, even though she must depend on her son to carry her to the polling place.AP

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Shared Grief When Seung-Hui Cho, a dis- turbed student, killed 32 people and wounded 17 on the campus of Virginia Tech in April 2007, many outsiders looked for something or someone to blame—the university’s security arrangements and mental health policies, the state’s gun laws, even Korean Americans as a group. Students, preferring to seek meaning rather than blame, gathered to pray, sing, and embrace one another.

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Coverage of Diversity Cross-cultural, international, multiethnic, rich and poor, old and young, male and female, newborn and centenarian—all these words and ideas are vital to appreciat- ing how we all develop. Research uncovers surprising commonalities and notable differences: We are all the same, yet each of us is unique. From the discussion of social contexts in Chapter 1 to the coverage of cultural differences in mourning in the Epilogue, each chapter highlights the possibilities and variations of human life. New research on family structures, immigrants, bilingualism, and ethnic differ- ences in health are among the many topics that illustrate human diversity. Listed here is a smattering of the discussions of culture and diversity in this new edition. Respect for human differences is evident throughout. You will note that examples and research findings from many parts of the world are included, not as add-on highlights, but as integral parts of the description of each age.

Defining diversity, p. 4 Multiculturalism as a characteristic of development, p. 7 Defining culture, pp. 10–11 Ethnicity, race, and income, p. 11 Issues and Applications: “My Name Wasn’t Mary,” about Maya Angelou, pp. 12–13 Three domains of human development, p. 13 Response for social scientists, p. 23 Culture as one major difference between Erikson’s and Freud’s theories, pp. 36–37 Sociocultural theory, pp. 46–48 Sociocultural theory and nature vs. nurture, p. 54 Sexual orientation and identity differences according to culture, p. 56 Issues and Applications: Too Many Boys? p. 65 Shyness: Genotype or phenotype? Cultural differences, p. 74 Addiction, personality, and culture, pp. 74–75 Cultural variations in visual acuity, pp. 75–76 Practical applications of the nature vs. nurture argument, p. 77

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Learning from One Another Every nation creates its own version of early education. In this scene at a nursery school in Kuala Lumpur, Malaysia, note the head coverings, uniforms, bare feet, and absence of boys. None of these elements would be found in most early-childhood education classrooms in North America or Europe.

Observation Quiz (see answer, page 252): What seemingly universal aspects of child- hood are visible in this photograph? PAU

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International and domestic diversity in low birthweight, pp. 113–114 International variations in birthing procedures, pp. 110–111 Social support and birth issues: Cultural differences, p. 116 Family sleeping arrangements as an example of cultural traits, p. 128 Association between adoption and IQ of institutionalized Romanian children,

pp. 134–135 Ethnic variations in the development of motor skills, pp. 141–142 Ethnicity, infant-care routines by culture, and SIDS, pp. 146–147 Infant nutrition worldwide, pp. 148–150 Cultural variations in language development, pp. 169–171 Influence of culture on emotion, p. 180–181 Applying Erikson’s theories across cultures, p. 184 Cross-cultural application of epigenetic theory, p. 185–186 Sociocultural theory, pp. 188–190 Attachment and culture, pp. 193–195 Social referencing, p. 196 Eating habits, p. 208 Cultural adaptation to fine motor skills, p. 217–218 Guided participation (Vygotsky) and social activities, p. 234 Culture and the development of theory of mind, pp. 238–239 International comparison: Children’s performance on false-belief tests, p. 239 Language: Word-mapping and culture, p. 241 Bilingualism, cognition, and culture, pp. 244–245 Intrinsic motivation: Emotional regulation and culture, p. 258 Cultural emphasis on prosocial and antisocial behavior, p. 260 How empathy is taught: American vs. Japanese culture, p. 261 Cultural variations in parenting during early childhood, pp. 265–266 Punishment styles by culture, pp. 266–268 Amount of media exposure in various cultures, p. 269 Sociocultural theory and developing gender roles, pp. 275–276 Gender and destiny, p. 277 Size and shape of children, pp. 284–286 Influence of culture on motor skills, p. 287

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Four Generations of Caregiving These four women, from the great-grandmother to her 17-year-old great-granddaughter, all care for one another. Help flows to whoever needs it, not necessarily to the oldest or youngest.PH

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IQ testing, pp. 293–294 Thinking Like a Scientist: Prescription Drugs, p. 298 Cultural variations in cognition and education in the school years, pp. 309–310 Spectrum disorders and culture, p. 300 Control processes and culture, pp. 312–313 Second-language learning, pp. 315–316 Education around the world, pp. 318–321 International educational assessment, pp. 321–324 Comparison of education in the United States and Japan, pp. 323–324 Culture and education, pp. 328–329 Maintaining tradition in the classroom, p. 330 The culture of children worldwide, pp. 334–337 Friendship and culture, p. 339 Study of bullying in Norwegian schools, p. 341 Diverse household structures, pp. 345–346 Family structure: Culture and ethnic differences, p. 348–350 Cultural variations in parenting and family roles, pp. 349–350 Cultural differences in self-concept/self-esteem, p. 353 Social support and religious faith, pp. 355–356 Impact of environment on the timing of puberty, pp. 366–368 Sexual maturation in various cultures, pp. 373–375 Cultural attitudes toward pregnancy, pp. 380–381 Drug use: Variations by nation, gender, and ethnicity, pp. 384–385 Formal operational thought and culture, p. 395 Identity and religion, ethnicity, and vocation worldwide, pp. 416–419 Teaching and learning, pp. 406–407 International comparisons: Average problem-solving scores among 15-year-olds,

p. 408 Adults and teenage conflict: Cultural values, pp. 419–420 United States high school dropout rates by race, p. 410 The peer group for immigrant teens, pp. 425–427 Immigrant youth, p. 425 Adolescent sexuality and culture, pp. 427–429 Sex education: Differences by culture, p. 431 Depression and culture, p. 434–435 Teen suicide rates in various cultures, pp. 435–436 Culture and ages and stages of growth, strength and health, pp. 447–449 Emotional stress and culture, p. 454 Nutrition and culture, p. 457 Eating disorders and culture, p. 459, 461 Cultural variations on violence, p. 466 Kohlberg’s postformal thought and culture, pp. 472–473 Stereotype threat, pp. 471, 477–480 Dialectical thought and culture, pp. 480–482 Morals and culture, pp. 483–484 Ethnic identity, pp. 500–502 Anxiety disorders within the cultural context, p. 520 Culture and obesity, p. 542 Diversity and intelligence, pp. 564–565 Culture, cohort, and SES, p. 580 Culture and personality, p. 583 Divorce rates and predictors by culture, p. 595

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Diversity and employment, p. 605 Cultural effects of wisdom, p. 27 Centenarians around the world, pp. 643–644 Ethnic discrimination in late adulthood, pp. 687–689 Views of death in major religions, Ep-6–Ep-10 A Case to Study: “Ask My Son and My Husband”; cultural views of communi-

cation about dying, pp. Ep-11–Ep-12

Up-to-Date Coverage I learned from my mentors curiosity, creativity, and skepticism; as a result, I am eager to read and ready to analyze the thousands of journal articles and books on everything from Alzheimer’s to zygosity. The recent explosion of research in neu- roscience and genetics has challenged me, once again, first to understand and then to explain many complex findings and speculative leaps. My students con- tinue to ask questions and share their experiences, always providing new perspec- tives and concerns.

Topical Organization within a Chronological Framework The book’s basic organization remains unchanged. Four chapters begin the book with coverage of definitions, theories, genetics, and prenatal development. These chapters function not only as a developmental foundation but also as the structure for explaining the life-span perspective, plasticity, nature and nurture, multicul- tural awareness, risk analysis, the damage-repair cycle, family bonding, and many other concepts that yield insights for all of human development.

The other seven parts correspond to the major periods of development. Each part contains three chapters, one for each of the three domains: biosocial, cogni- tive, and psychosocial. The topical organization within a chronological framework is a useful scaffold for students’ understanding of the interplay between age and domain. The chapters are color-coded with tabs on the right-hand margins. The pages of the biosocial chapters have green tabs, the cognitive chapters have purple tabs, and the psychsocial chapters have pink tabs.

Four Series of Integrated Features Four series of deeper discussions appear as integral parts of the text, and only where they are relevant. Readers of earlier editions have particularly liked these series. The categories are “In Person,” “A Case to Study,” “Thinking Like a Scientist,” and “Issues and Applications.”

Pedagogical Aids Each chapter ends with a summary, a list of key terms (with page numbers indi- cating where the word is introduced and defined), key questions, and three or four application exercises designed to let students apply concepts to everyday life. Key terms appear in boldface type in the text and are defined in the margins and again in a glossary at the back of the book. The outline on the first page of each chapter and the system of major and minor subheads facilitate the survey- question-read-write-review (SQ3R) approach. A “Summing Up” feature at the end of each section provides an opportunity for students to pause and reflect on

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what they’ve just read. Observation quizzes inspire readers to look more closely at certain photographs, tables, and graphs. The “Especially for . . . ” questions in the margins, many of which are new to this edition, apply concepts to real-life careers and social roles.

Photographs, Tables, and Graphs That Are Integral to the Text Students learn a great deal from this book’s illustrations, because Worth Publishers encourages authors to choose the photographs, tables, and graphs and to write captions that extend the content. Appendix A furthers this process by presenting a chart or table for each chapter that contains detailed data for further study.

Supplements As an instructor myself, I know that supplements can make or break a class. I personally have rejected textbook adoptions because I knew that that publisher historically had provided inaccurate test banks, dull ancillaries, and slow service. That is not the case with Worth Publishers, which has a well-deserved reputation for providing supplements that are extensive and of high quality, for both profes- sors and students. With this edition you will find:

Exploring Human Development: A Media Tool Kit For this edition, the acclaimed Media Tool Kit takes a technological leap forward. Our materials will now be available online for students and instructors—as well as on CD and (for instructors) VHS and DVD. The tool kit was prepared by a talented team of instructors, including: Victoria Cross, University of California, Davis; Sheridan Dewolf, Grossmont College; Pamela B. Hill, San Antonio College; Lisa Huffman, Ball State University; Thomas Ludwig, Hope College; Cathleen McGreal, Michigan State University; Amy Obegi, Grossmont College;

xxx PREFACE

Same Birthday, Same (or Different?) Genes Twins who are of different sexes or who have obvious differences in personality are dizygotic, sharing only half of their genes. Many same-sex twins with similar temperaments are dizygotic as well. One of these twin pairs is dizygotic; the other is monozygotic.

Observation Quiz (see answer, page 72): Can you tell which pair is monozygotic?

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Especially for Teachers You are teaching in a school that you find too lax or too strict, or with parents who are too demanding or too uncaring. Should you look for a different line of work?

➤Response for Teachers (from page 324): Nobody works well in an institution they hate, but, before quitting the profession, remember that schools vary. There is probably another school nearby that is much more to your liking and that would welcome an experienced teacher. Before you make a move, however, assess the likelihood that you could adjust to your current position in ways that would make you happier. No school is perfect; nor is any teacher.

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Michelle L. Pilati, Rio Hondo College; Tanya Renner, Kapiolani Community College; Catherine Robertson, Grossmont College; Stavros Valenti, Hofstra University; and Pauline Zeece, University of Nebraska, Lincoln.

The media activities now offered range from investigations of classic experiments (like the visual cliff and the strange situation) to observations on children’s play and adolescent risk taking. More than 50 video clips and animations have been added for this edition—including a stunning new animation of brain development from birth until late life, classic historical footage from Harry Harlow, and spellbinding new footage from a variety of news sources on topics ranging from children in war to the biology of love in middle age. The assessment available on the student tool kit has also been updated and revised—students now can get a better assessment of their learning through randomized, timed quizzes from a large quiz-bank pool.

For instructors, the tool kit includes more than 350 video clips and animations, along with discussion starters and PowerPoint slides available as a set of CD-ROMs, DVDs, VHS tapes, or an online database of more than 350 video clips. The student tool kit includes 49 interactive activities, quizzes, and flashcards. The online student tool kit (available in the spring of 2008) includes more than 70 activities.

PsychPortal This is the complete online gateway to all the student and instructor resources available with the textbook. PsychPortal brings together all the resources of the media tool kits, integrated with an eBook and powerful assessment tools to com- plement your course. The ready-to-use course template is fully customizable and includes all the teaching and learning resources that go along with the book, pre- loaded into a ready-to-use course; sophisticated quizzing, personalized study plans for students and powerful assessment analyses that provide timely and useful feedback on class and individual student performance; and seamless integration of student resources, eBook text, assessment tools, and lecture resources. The quiz bank (featuring more than 80 questions per chapter) that powers the student assessment in both PsychPortal and the Media Tool Kit was written by Pamela Hill, San Antonio College, and Michelle L. Pilati, Rio Hondo College. These questions are not from the test bank!

eBook The beautiful and interactive eBook fully integrates the complete text and its elec- tronic study tools in a format that instructors and students can easily customize— at a significant savings on the price of the printed text. It offers easy access from any Internet-connected computer; quick, intuitive navigation to any section or subsection, as well as any printed book page number; a powerful notes feature that allows you to customize any page; a full-text search; text highlighting; and a full, searchable glossary.

Companion Web Site Edited by Catherine Robertson, Grossmont College, the companion Web site (at www.worthpublishers.com/berger) is an online educational setting for students and instructors. It is free, and tools on the site include interactive flashcards in both English and Spanish; a Spanish language glossary; quizzes; annotated Web Links; and Frequently Asked Questions About Development. A password- protected Instructor Site offers a full array of teaching resources, including PowerPoint slides, an online quiz gradebook, and links to additional tools.

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“Journey Through the Life Span” Observational Videos Bringing observational learning to the classroom, this video series allows students to watch and listen to real children as a way of amplifying their reading of the text. “Journey Through the Life Span” offers vivid footage of people of all ages from around the world (North America, Europe, Africa, Asia, and South America), as seen in everyday environments (homes, hospitals, schools, and offices) and at major life transitions (birth, marriage, divorce, being grandparents). Interviews with prominent developmentalists—including Charles Nelson, Barbara Rogoff, Ann Peterson, and Steven Pinker—are integrated throughout to help students link research and theory to the real world. Interviews with a number of social workers, teachers, and nurses who work with children, adults, and the aged give students direct insight into the practical challenges and rewards of their voca- tions. One hour of unedited footage helps students sharpen their observation skills. Available on VHS and DVD.

“Scientific American Frontiers” Videos for Developmental Psychology This remarkable resource provides instructors with 17 video segments of approxi- mately 15 minutes each, on topics ranging from language development to nature–nurture issues. The videos can be used to launch classroom lectures or to emphasize and clarify course material. The Faculty Guide by Richard O. Straub (University of Michigan) describes and relates each segment to specific topics in the text.

Life-Span Development Telecourse Transitions Through the Life Span, developed by Coast Learning Systems and Worth Publishers, teaches fundamentals of human development. The course also explores the variety of individual and developmental contexts that influence development, such as socioeconomic status, culture, genetics, family, school, and society. Each video lesson includes specific real-life examples interwoven with commentary by subject matter experts. The course includes 26 half-hour video lessons, a telecourse study guide, and a faculty manual with test bank. The test bank is also available electronically.

eLibrary The Worth Publishers eLibrary brings together all the existing text and supple- mentary resources in a single, easy-to-use Web interface. This searchable, Web- based integrator includes materials from the textbook, the Instructor’s Resources, and select electronic supplements, including PowerPoint slides and video clips. Through simple browse-and-search tools, instructors can quickly access virtually any piece of content and either download it to a computer or create a Web page to share with students. The eLibrary also features prebuilt, customizable collections for each chapter, allowing adopters to quickly access the “best of” the eLibrary and adapt it for their needs.

Instructor’s Resources This collection of resources written by Richard O. Straub (University of Michigan, Dearborn) has been hailed as the richest collection of instructor’s resources in

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developmental psychology. This manual features chapter-by-chapter previews and lecture guides, learning objectives, springboard topics for discussion and debate, handouts for student projects, and supplementary readings from journal articles. Course planning suggestions, ideas for term projects, and a guide to audiovisual and software materials are also included.

Study Guide The Study Guide by Richard O. Straub helps students evaluate their understand- ing and retain their learning longer. Each chapter includes a review of key con- cepts, guided study questions, and section reviews that encourage students’ active participation in the learning process. Two practice tests and a challenge test help them assess their mastery of the material.

PowerPoint Slides A number of different presentation slides prepared by Madeleine L. Tattoon, Riverside Community College, are available on the Web site or on the Exploring Human Development: Instructor’s Media Tool Kit CD-ROM. There are two pre- built PowerPoint slide sets for each text chapter—one featuring chapter outlines, the other featuring all chapter art and illustrations. These slides can be used as is or customized to fit individual needs. Video presentation slides provide an easy way to connect chapter content to the selected video clip and follow each clip with discussion questions designed to promote critical thinking. In addition, Madeline Tattoon has produced a set of enhanced lecture slides focusing on key themes from the text and featuring tables, graphs, and figures.

Overhead Transparencies This set of 50 full-color transparencies consists of key illustrations, charts, graphs, and tables from the textbook.

Test Bank and Computerized Test Bank The test bank, prepared by Vivian Harper (San Joaquin Delta College) and myself, includes at least 90 multiple-choice and 70 fill-in, true-false, and essay questions for each chapter. Each question is keyed to the textbook by topic, page number, and level of difficulty. The Diploma computerized test bank, available on a dual- platform CD-ROM for Windows and Macintosh, guides instructors step by step through the process of creating a test, and it allows them to quickly add an unlim- ited number of questions, edit, scramble, or resequence items, format a test, and include pictures, equations, and media links. The accompanying gradebook en- ables instructors to record students’ grades throughout the course and includes the capacity to sort student records, view detailed analyses of test items, curve tests, generate reports, and add weights to grades.

The CD-ROM is also the access point for Diploma Online Testing, which allows instructors to create and administer secure exams over a network or over the Internet. In addition, Diploma has the ability to restrict tests to specific com- puters or time blocks. Blackboard- and WebCT-formatted versions of each item in the Test Bank are available on the CD-ROM.

PREFACE xxxiii

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xxxiv PREFACE

In addition, I wish to thank the instructors who participated in our online survey. We’ve tried very hard to apply the insights gained from their experiences with the sixth edition to make this new edition better.

Jackie Adamson, South Dakota School of Mines & Technology

Karin Alaniz, University of Minnesota, Twin Cities Carol Allen, Miami-Dade Community College, North Ariel Anderson, Western Michigan University Don Beach, Tarleton State University Kaye Bedell, Gavilan College Mara Bentley, Los Angeles Southwest College Mark Birchfield, Warner Southern College Margaret Bischoff, South Texas College Kathryn Bojczyk, Florida State University

Devorah Bozella, Mount Aloysius College Michael Brislawn, Bellevue Community College Chris Burkett, Newberry College Shawn Christiansen, Southern Utah University Aileen Collins, Chemeketa Community College Melanie Conti, College of Saint Elizabeth Elizabeth DeGiorgio, Mercer County Community College Deborah Dobay, Chemeketa Community College Jill Durby, Fullerton College Pamela Fergus, Minneapolis Community & Technical

College

TeneInger Abrom-Johnson, Prairie View A&M University Jackie Adamson, South Dakota School of Mines

& Technology Ryan Allen, The Citadel Tracy C. Babcock, Montana State University Don M. Beach, Tarleton State University Kathryn Bojczyk, Florida State University Tanya Boone, California State University, Bakersfield Jennifer L. Boothby, Indiana State University Janine P. Buckner, Seton Hall University Paul Burinskas, University of Hartford Tracie Burt, Southeast Arkansas College Amy Carrigan, University of Saint Francis Julia W. Chang, Mount St. Mary’s College Aileen M. Collins, Chemeketa Community College Patricia Ann Crowe, North Iowa Area Community College John Crumlin, University of Colorado at Colorado Springs Linda De Villers, Chaffey College Jacqueline Elder, Triton College Tony Fowler, Florence-Darlington Technical College Don Gasparini, Manhattan College Jessica Gillooly, Glendale Community College Lynn Haller, Morehead State University Myra M. Harville, Holmes Community College Scott L. Horton, University of Southern Maine, and Mitchell

College Tasha R. Howe, Humboldt State University Alycia M. Hund, Illinois State University David P. Hurford, Pittsburg State University

Russ Isabella, University of Utah D. Lamar Jacks, Santa Fe Community College Jeffrey S. Kaplan, University of Central Florida Michelle L. Kelley, Old Dominion University Kristina T. Klassen, Northern Idaho College Joseph Lao, Teachers College Brian McCoy, Nichols College Joann M. Montepare, Emerson College Melissa Baartman Mork, Northwestern College Ronnie Naramore, Angelina College Alison Paris, Claremont McKenna College Robert Pasnak, George Mason University Michelle L. Pilati, Rio Hondo College Curtis D. Proctor-Artz, Wichita State University, School of

Social Works Celinda M. Reese, Oklahoma State University Lilian M. Romero, San Jacinto College Central Campus Rosalind Shorter, Jefferson Community College Peggy Skinner, South Plains College James E. Snowden, Midwestern State University Kevin Sumrall, Montgomery College Margot Sutorius, Northern Illinois University Donna Thompson, Midland College R. Bruce Thompson, University of Southern Maine Dean D. VonDras, University of Wisconsin—Green Bay Robert W. Wildblood, Indiana University Kokomo Wanda A. Willard, Monroe Community College Betsy Wisner, SUNY Cortland

Thanks I’d like to thank the academic reviewers who have read this book in every edition and who have provided suggestions, criticisms, references, and encouragement. They have all made this a better book. I want to mention especially those who have reviewed this edition:

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The editorial, production, and marketing people at Worth Publishers are dedi- cated to meeting the highest standards of excellence. Their devotion of time, effort, and talent to every aspect of publishing is a model for the industry. I particularly would like to thank Stacey Alexander, Jessica Bayne, Anthony Calcara, Cele Gardner, Lorraine Klimowich, Tom Kling, Tracey Kuehn, Paul Lacy, Sharon Merritt, Katherine Nurre, Donna Ranieri, Babs Reingold, Amy Shefferd, Walter Shih, Barbara Seixas, Ted Szczepanski, Vivien Weiss, and Catherine Woods.

Dedication Billions of people worldwide deserve respect, but humans focus better on one person at a time. Accordingly, I dedicate this book to Jean Montreville, the father of the family in sanctuary at Judson Memorial Church.

New York, September 2007

PREFACE xxxv

Don Gasparini, Manhattan College Michael Gibbons, Southern Virginia College Marian Gibney, Phoenix College Stacey Glaesmann, San Jacinto College Drusilla Glascoe, Salt Lake Community College Arthur Gonchar, University of La Verne Christina Gotowka, Tunxis Community College Amy Guimond, Arizona State University Lisa Hager, Spring Hill College Lynn Haller, Morehead State University Abby Heckman, Georgia Institute of Technology Susan Higgins, Pennsylvania Valley Community College Elaine Hogan, University of North Carolina at Wilmington Scott Horton, University of Southern Maine Abbie Jenks, Greenfield Community College David Johnson, John Brown University Jennifer Jones, University of New Mexico Barbara Kabat, Sinclair Community College Wendy Kallina, Macon State College Janice Kennedy, Georgia Southern University Veena Khandke, Univ of South Carolina, Spartanburg Barbara Lusk, Collin County Community College Brian McCoy, Nichols College

Elizabeth Miller, Northern Illinois University Nicholas Murray, East Carolina University Regina O’Shea-Hockett, Great Basin College-Elko Rosamaria Pena, Laredo Community College Donald Ratcliff, Vanguard University Kristina Roberts, Barstow College Edna Ross, University of Louisville Linda Russ, SUNY University at Buffalo Jonathan Schindelheim, Tufts University Eliezer Schnall, Touro College Peggy Skinner, South Plains College Kevin Sumrall, Montgomery College Margo Sutorius, Northern Illinois University Lynda Szymanski, College of Saint Catherine Byron Tharpe, Jefferson Community College, Southwest Kathy Tinsley, Central Carolina Community College Paul Toscano, College of Southern Maryland Connie Veldink, Everett Community College Catherine Wambach, University of Minnesota, Twin Cities Diane Weber, Gardendale High School Larry Weiss, Suffolk County Community College Steve Wisecarver, Lord Fairfax Community College

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The Beginnings

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CHAPTER 1

CHAPTER 2

CHAPTER 3

CHAPTER 4 he science of human development has

many beginnings.

Chapter 1 introduces what we study,

why, and how. Chapter 2 explains five

theories that organize and guide our study. Chapter

3 traces the interaction of heredity and environment,

the interplay between the chemical instructions on

the genes and the nurturance of the surroundings,

from the mother’s prenatal diet to the care of the

hospice nurse. Chapter 4 details the beginning of

human life, from a single dividing cell to a fully

formed newborn.

Together these four chapters start our study of

human life. A journey around the globe begins with

a single step; a life span begins with a millisecond.

Turn the page.

PA R T I

1

T

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Introduction

What will happen to the baby just born, or to the schoolchildtrying to make a friend, or to the emerging adult wonderinghow to pay for college, or to the elder contemplating retire-ment? What about you, or your child, or your father—how does anyone become who they are, and what will happen to them tomorrow or 30 years from now? This book is about those people and billions of others, worldwide.

Why should you care? There are dozens of reasons. Some are explained in this chapter and others will become evident as you study. Here is one now: You will look more closely at the people around you, making small moments precious.

This happened to me. I entered my 8-month-old baby’s room to be surprised by a smile and

“hahh” as she held on to the slats of her crib, bending her chubby little legs excitedly.

“Hi, Elissa,” I grinned back. “You’re talking!” Few people would consider “hahh” talking. But I had learned that lan-

guage starts with noises and gestures, months before the first identifiable words. I was delighted. You will be joyful, too, in moments you might not have noticed before today.

Defining Development The science of human development seeks to understand how and why people—all kinds of people, everywhere—change or remain the same over time. This definition has three crucial elements.

Science First, and most important, developmental study is a science. It depends on theories, data, analysis, critical thinking, and sound methodology, just like every other science does. The goal is to understand “how and why,” to dis- cover the processes of development and the reasons for it. As scientists, we ask questions and seek answers.

Science cannot decide the purpose of life; we need philosophy or religion for that. Literature and art can also provide insight beyond the scientific experiment. But “the empirical sciences will show us the way, the means, and the obstacles” involved in making life what we want it to be (Koops, 2003, p. 18).

1

3

CHAPTER OUTLINE

� Defining Development

Science Diversity Connections Between Change and Time

� Five Characteristics of Development

Multidirectional Multicontextual Multicultural ISSUES AND APPLICATIONS:

My Name Wasn’t Mary Multidisciplinary Plasticity A CASE TO STUDY: My Nephew David

� Developmental Study as a Science

Steps of the Scientific Method Ways to Test Hypotheses Studying Change over Time

� Cautions from Science

Correlation and Causation Quantity and Quality Ethics in Research

science of human development The sci- ence that seeks to understand how and why people change or remain the same over time. Developmentalists study people of all ages and circumstances.

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To say that something is empirical means that it is based on data, on many experiences, on demonstrations, on facts. Empirical sciences enable people to live full lives. Without scientific conclusions followed by applications, human life might be “solitary, poor, nasty, brutish, and short,” as it was for most people before the scientific revolution (Hobbes, 1651/1997).

Diversity Second, we study all kinds of people—young and old; rich and poor; of every eth- nicity, background, sexual orientation, culture, and nationality. The challenge is to identify universalities (beyond birth and death) and differences (beyond every- one’s unique genetic code) and then to describe them in ways that simultaneously distinguish and unify all humans.

For example, when you first meet someone, you recognize that person as human (universal) and as your age, or older, or younger (differences within univer- sals; we all have an age). But when you think about yourself or someone you know well, you realize how much more complex each person is. In some ways you are atypical for your age—everyone is. Perhaps you are “wise beyond your years” or you still look at the world with “childlike wonder.” Developmental scientists seek to convey both: the generalities and the specifics.

Fiction writers can offer insights in this area, too. In one novel, a vehemently anti-Communist Cuban American asks her teenage daughter to paint a mural of the Statue of Liberty for the opening of a new store. At the public unveiling, the mother sees the mural for the first time: Liberty’s torch floats above her grasp and a safety pin is stuck through her nose. The daughter reports:

The blood has drained from my mother’s face and her lips are moving as if she wants to say something but can’t find the words. . . . A lumpish man charges Liberty with a pocket knife. . . . Mom swings her new handbag and clubs the guy cold, inches from the painting. . . . And I, I love my mother very much at that moment.

[Garcia, 2004, pp. 143, 144]

As for specifics, did this episode actually happen? No, probably not (it appears in a work of fiction). As for generalities, can mother–daughter love overcome gen- erational and political differences? Yes. Researchers have documented the power of family bonds; the dramatic power of this incident arises from that universality.

You might wonder how a novel relates to science, since science, unlike art, depends on objective data, empirical observations, and tested theories. Yet the struggle to understand both the universal and the unique in all kinds of people is the goal of both artists and scientists—and, for that matter, of philosophers, preachers, and every other thoughtful person. Using science to study people is an effective means to that end.

Connections Between Change and Time The third crucial element of the definition is change or remain the same over time. The science of human development includes all the transformations and consis- tencies of human life, from the very beginning to the very end. There is a “recipro- cal connection between age-focused developmental specialties [such as infancy, childhood, adolescence, adulthood] and their integration into a life span view” (Baltes et al., 2006, p. 644). That is, each stage is better understood by remember- ing the whole life, and, conversely, the whole life is understood best by knowing each segment.

empirical Based on observation, experience, or experiment; not theoretical.

4 CHAPTER 1 ■ Introduction

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Dynamic-Systems Theory This emphasis on the interaction between people and within each person, such as between parent and child, between prenatal and postnatal life, between ages 2 and 102, is central to the study of the life span. One way to highlight this is via dynamic-systems theory, which stresses fluctuations and transitions, “the dynamic synthesis of multiple levels of analysis” (Lerner et al., 2005, p. 38).

The word systems captures the idea that a change in one part of a person, or family, or society will affect all the other aspects of development, because each part is connected to all the other parts. Dynamic-systems theory may be a new “grand theory of development” (traditional grand theories are explained in Chapter 2) (Spencer et al., 2006, p. 1521). In any case, this perspective is pervasive throughout the human life span, since every moment of life affects all the others.

Applying dynamic-systems theory to human development is a “relatively new” effort (Thelen & Smith, 2006, p. 258), but this perspective has aided natural sci- entists for over 50 years. They have recognized that systemic change over time is the nature of life:

Seasons change in ordered measure, clouds assemble and disperse, trees grow to certain shape and size, snowflakes form and melt, minute plants and animals pass through elaborate life cycles that are invisible to us, and social groups come together and disband.

[Thelen & Smith, 2006, p. 271]

Bioecological Systems A leader in understanding levels of development was Urie Bronfenbrenner, who recommended an ecological-systems approach to developmental study. He argued that, just as a naturalist studying an organism examines the ecology, or the interrelationship of the organism and its environment, developmentalists need to examine all the systems that surround the development of each person.

These systems continue to unfold over the natural course of the human life, affecting every thought, action, and emotion (Bronfenbrenner & Morris, 2006). Bronfenbrenner described three nested levels that affect each person (diagrammed in Figure 1.1): microsystems (elements of the person’s immediate surroundings, such as family and peer group), exosystems (such local institutions as school and church), and macrosystems (the larger social setting, including cultural values, eco- nomic policies, and political processes).

Bronfenbrenner also recognized that conditions change over time, and therefore the chronosystem (historical conditions) affects the other three systems. Appreciat- ing the dynamic interaction between the microsystem, the exosystem, and the macrosystem led him to name a fifth system, the mesosystem, which involves the connections between systems or between parts of a single system.

One example of a mesosystem is all the connections between home and school, including all the communication processes (letters home, parent–teacher conferences, phone calls, back-to-school nights) between a child’s parents and teachers. Another mesosystem is all the connections between work and family, not only direct connections such as family-leave policies and work hours but also connections between such macrosystem factors as unemployment rates, which affect the microsystems of those families in which the head of household cannot find work.

Bronfenbrenner particularly objected to capturing the artificial behavior of a person at one moment, without considering how that behavior has been shaped by overarching systems. Referring in 1974 to research on mother–child attachment (discussed in Chapter 7), he complained, “Much of contemporary developmental

dynamic-systems theory A view of human development as always changing. Life is the product of ongoing interaction between the physical and emotional being and between the person and every aspect of his or her environment, including the family and society. Flux is constant, and each change affects all the others.

Defining Development 5

ecological-systems approach A vision of how human development should be stud- ied, with the person considered in all the contexts and interactions that constitute a life.

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psychology is the science of the strange behavior of children in strange situations with strange adults for the briefest possible period of time” (p. 1).

Throughout his life, Bronfenbrenner emphasized the importance of studying humans in natural settings, as they actually live their lives. His emphasis on the dynamic biological systems that allow ongoing change inspired him to rename his theory from ecological to bioecological (Bronfenbrenner & Morris, 2006). A similar perspective is found in dynamic-systems theory, which holds that “thought is al- ways grounded in perception and action” (Spencer et al., 2006, p. 1529).

This idea that each person develops in various nested contexts, which overlap and interact over time, is central to a dynamic-systems approach to life-span development (Thelen & Smith, 2006) as well as to the bioecological perspective (Bronfenbrenner & Morris, 2006). You will soon see this in all five of the charac- teristics of life-span study, as well as throughout this book.

SUMMING UP

The science of human development seeks to understand how and why people—all kinds of people, everywhere—change or remain the same over time. As a science, it seeks empirical data to answer crucial questions regarding humans of every age and back- ground. In stressing change, the study of development is dynamic, never static, and focuses on the interaction among people and among the nested levels of influence that external systems have on individual persons.

■

6 CHAPTER 1 ■ Introduction

MICROSYSTEMS

EXOSYSTEM

MACROSYSTEM

Family Classroom

Religious Setting

Peer Group

School System

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S ocial Conditions

Econom ic Patterns

M es

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Mesosystem M

eso system

Mesosystem

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CHRONOSYSTEM

FIGURE 1.1

The Ecological Model According to develop- mental researcher Urie Bronfenbrenner, each person is significantly affected by interactions among a number of overlapping systems, which provide the context of development. Microsystems—family, peer groups, class- room, neighborhood, house of worship— intimately and immediately shape human development. Mesosystems refer to interac- tions among microsystems, as when parents coordinate their efforts with teachers to edu- cate the child. Surrounding and supporting the microsystems are the exosystems, which include all the external networks, such as community structures and local educational, medical, employment, and communications systems, that influence the microsystems. Influencing all three of these systems is the macrosystem, which includes cultural values, political philosophies, economic patterns, and social conditions. Bronfenbrenner later added a fifth system, the chronosystem, to empha- size the importance of historical time.

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Five Characteristics of Development Developmentalists (people from many academic disciplines who study human de- velopment) are acutely aware of the reciprocal connection between one moment in life and another. This awareness leads them to five principles that are useful for understanding any age of human life (Baltes et al., 2006; Staudinger & Linden- berger, 2003).

■ Multidirectional. Change occurs in every direction, not always in a straight line. Gains and losses, predictable growth and unexpected transformations, are evident.

■ Multicontextual. Human lives are embedded in many contexts, including historical conditions, economic constraints, and family patterns.

■ Multicultural. Many cultures—not just between nations but also within them—affect how people develop.

■ Multidisciplinary. Numerous academic fields—especially psychology, biology, education, and sociology, but also neuroscience, economics, religion, anthropology, history, medicine, genetics, and many more—contribute data and insights.

■ Plasticity. Every individual, and every trait within each individual, can be altered at any point in the life span. Change is ongoing, although neither random nor easy.

Each of these five principles merits further explanation.

Multidirectional The study of human development is the study of change; development is dynamic, not static. Developmentalists sometimes analyze each fraction of a second, as when a barely perceptible change in a newborn’s face reflects a parent’s fleeting glance (e.g., Lavelli & Fogel, 2005). More often years, not seconds, are analyzed, revealing unexpected twists and turns.

Gains and Losses In studying dynamic systems, developmentalists have discovered that each aspect of life (physical health, intellectual growth, social interaction) is multidirectional; any direction—up, down, stable, or erratic—is possible. There is evidence for simple growth, radical transformation, improvement, and decline as well as for continuity—day to day, year to year, and generation to generation (see Figure 1.2). A gain and a loss may occur at the same time, or a loss may lead to a gain or vice versa (Baltes et al., 2006).

When movement occurs, the cause could be something that seems tangential, because the person is systemically affected by a change in any aspect of development. An apparent loss in one di- mension is often accompanied by a gain in another. The emphasis on multidirectional change is particularly important in late adulthood, because during old age people tend to focus on the declines, not on the gains. One gain is that many older people become more nurturant toward other family members.

This may be clearer with another example. When newborn babies are held up in a standing position, they move their legs as if walking. It was once thought that this stepping reflex disappeared at about 3 months. At birth, babies have many other reflexes that seem to disappear later. For decades, developmentalists hypothesized that these disappearances reflected losses in brain function, which

Especially for College Students Which pattern of developmental growth best describes the change from high school to college?

Five Characteristics of Development 7

Growth

Continuity

Time

Growth and decline

Unpredictable

Growth in stages

Linear growth

FIGURE 1.2

Patterns of Developmental Growth Many patterns of developmental growth have been discovered by careful research. Although linear (or near-linear) progress seems most common, scientists now find that almost no aspect of human change follows the linear pattern exactly.

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they believed were necessary for more advanced brain processes to occur. How- ever, later researchers found that babies still make stepping movements when they are lying on their backs or when their lower bodies are in water. This observa- tion led to the idea that possibly less is lost than is gained. Aha: 3-month-olds have become heavier; their little legs cannot support them, and that’s why step- ping disappears while standing but not when on their backs or in water (Thelen & Ulrich, 1991).

The Butterfly Effect One aspect of multidirectional study is that the eventual direction and power of change should not be judged immediately. Small changes may have large effects, because every change affects a dynamic system. The power of a small change is called the butterfly effect, after a 1972 speech by weather expert Edward Lorenz, titled “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?”

The idea of the butterfly effect is that, just as one drop of water might make an overfull glass suddenly spill over, so a small increase in wind velocity caused by a butterfly might be the final force that triggers a storm a thousand miles away. The possibility that small input may result in large output applies to human thoughts and actions as well (Masterpasqua & Perna, 1997). To use a developmental exam- ple, one cigarette smoked by a pregnant woman could result in a fetus’s death if it is already fragile and underweight for other reasons. Of course, most butterfly wings have no effects, nor do most single cigarettes. The butterfly effect means that a tiny event could have an enormous impact, not that it always does.

The opposite can occur: Large changes can affect people in contradictory ways. Lottery jackpot winners become euphoric and then less happy than before (Argyle, 2001; Gilbert, 2006). Christopher Reeve earned fame and fortune as a star in more than 40 films. When he became paralyzed, he first wanted to kill himself but soon welcomed life, explaining that he grew to appreciate other people much more (Reeve, 1999).

butterfly effect The idea that a small effect or thing can have a large impact if it happens to tip the balance, causing other changes that create a major event.

8 CHAPTER 1 ■ Introduction

AP P

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/ HI

DA JE

T DE

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Holding On Children from war-torn Kosovo rest at a refugee center near Sarajevo, Bosnia. They are actively coping with their situation as best they can, holding a friend, a little sister, or a loaf of bread in their arms.

➤Response for College Students (from page 7): All of them, depending on which aspect of development, in which person, is considered. As the text states, “Any direction is possible.”

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Multicontextual Humans develop in dozens of contexts that profoundly affect their development. Contexts include physical surroundings (climate, noise, population density, etc.) and family patterns. Here we explain only two aspects of the social context.

The Historical Context All persons born within a few years of one another are said to be a cohort, a group of people whose shared age means that they travel through life together. Those in a cohort are all affected by the values, events, technologies, and culture of their era. The war in Iraq has a different meaning for U.S. adults whose lives were changed by World War II, the Vietnam War, or the Gulf War.

If you doubt that national trends and events touch indi- viduals, consider your first name—a very personal word chosen especially for you. Look at Table 1.1, which lists the most popular names for boys and girls born into cohorts 20 years apart, beginning in 1925.

The popularity of your name is influenced by the era, and so is your reaction to it. If you are troubled that your name is popular, or rare, or old-fashioned, blame history, not your parents. Cohort affects many other aspects of de- velopment. Be grateful you were born after 1900, because severe beatings, deadly childhood diseases, and grueling child labor were common before then, when historical con- ditions resulted in many unwanted children.

The Socioeconomic Context When social scientists study the socioeconomic context, they often focus on socioeconomic status, abbreviated SES. Sometimes SES is called “social class” (as in “middle class” or “working class”).

SES involves more than money, in the form of income or wealth. It is also measured by factors such as occupation, education, and place of residence. The SES of a family consisting of, say, an infant, an unemployed mother, and a father who earns $15,000 a year would be low if the wage earner was an illiterate dish- washer living in an urban slum but would be much higher if that income was earned by a postdoctoral student living on campus and teaching part time.

cohort A group pf people who were born at about the same time and thus move through life together, experiencing the same historical events and cultural shifts.

socioeconomic status (SES) A person’s position in society as determined by income, wealth, occupation, education, place of residence, and other factors.

Five Characteristics of Development 9

TABLE 1.1

Which First Names for U.S. Girls and Boys Were Most Popular in 1925, 1945, 1965, 1985, and 2005?

Year Top Five Girls’ Names Top Five Boys’ Names Mary, Dorothy, Betty, Helen, Margaret Robert, John, William, James, Charles

Lisa, Mary, Karen, Kimberly, Susan Michael, John, David, James, Robert

Emily, Emma, Madison, Abigail, Olivia Jacob, Michael, Joshua, Matthew, Ethan

Mary, Linda, Barbara, Patricia, Carol James, Robert, John, William, Richard

Jessica, Ashley, Jennifer, Amanda, Sarah Michael, Christopher, Matthew, Joshua, Daniel

Guess First If your answers, in order from top to bottom, were 1925, 1965, 2005, 1945, and 1985, you are excellent at detecting cohort influences. If you made a mistake, perhaps that’s because the data are com- piled from applications for Social Security numbers during each year, so the names of those who did not get a Social Security number are omitted.

Computer Expert in a Baseball Cap Cohort differences become most apparent when new technology appears. Which age group is most likely to download music onto iPods or to send text messages on cellular phones?

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“And this is Charles, our web-master.”

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As this example illustrates, SES includes advantages and disadvantages, opportunities and limitations, past history and future prospects—all of which affect housing, nutrition, knowl- edge, and habits. Although low income obviously limits a per- son, other factors (such as education) can make poverty better or worse.

A question for developmentalists is whether low SES does most damage in infancy, when malnutrition, poor medical care, and low family education could stunt a baby’s brain, or in late adulthood, when accumulated stress overwhelms the body’s re- serves. The answer is not clear; SES is powerful at every age.

Multicultural Culture affects each human at every moment. Precisely be- cause culture is so pervasive, people rarely notice their culture while they are immersed in it—just as fish do not notice the water they are surrounded by.

Deciding What to Do Each Moment When social scientists use the term culture, they refer to the “patterns of behavior that are passed from one generation to the next . . . [and] that serve as the re- sources for the current life of a social group” (Cole, 2005, p. 49). The social group may be citizens of a nation, residents of a region within a nation, members of an ethnic group, people living in one neighborhood, or even students in a college class.

Any group may have its own culture—its own values, customs, clothes, dwellings, cuisine, and assumptions. Culture affects every action. For example, some students use highlighters, study in the library, and call professors by their first names; others do not. The reasons are cultural.

Cultures are dynamic, always changing, because children resist some tradi- tional values and adults abandon some aspects of their culture when historical, geographical, or family circumstances change (Smedley & Smedley, 2005). Each

10 CHAPTER 1 ■ Introduction

Culturally Acceptable Putting very young children to work is still a widespread custom in many parts of the world. The International Labor Organization estimates that, world- wide, 246 million children aged 5 to 17 are employed—often at very low wages. The children pictured here are working in an em- broidery shop in Pakistan.

Observation Quiz (see answer, page 12): Why are they using only their right hands?

The Culture of Poverty In this southern Illi- nois neighborhood, littered yards are part of a “culture of poverty” that also includes poor nutrition, substandard housing, and an aver- age life expectancy of 52 years.

Observation Quiz (see answer, page 13): A 13-year-old is in this photo, trying to garden. Can you find her?

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cohort experiences, and then transmits, a different culture than previous genera- tions did.

People are influenced by more than one culture. In multiethnic nations such as the United States and Canada, many individuals are multicultural, functioning not only within the dominant culture but also within various regional, ethnic, school, and other cultures.

Ethnicity, Race, and Income Confusion arises whenever people—scientists or nonscientists—refer to ethnic groups, races, cultures, and socioeconomic classes, because these categories over- lap. The preceding discussion and the following definitions should clarify the situ- ation.

People of an ethnic group share certain attributes, almost always ancestral heritage and often national origin, religion, culture, and language (Whitfield & McClearn, 2005). (Heritage refers to customs and traditions passed down to the present; national origin refers to one’s ancestors’ country of birth.) Ethnic cate- gories arise from history, sociology, and psychology, not from biology.

The term race, in contrast, has been used to categorize groups of people based on appearance. However, about 95 percent of the genetic differences between one person and another occur within, not between, supposed racial groups. Genetic variation is particularly apparent among dark-skinned people whose ancestors were African (Tishkoff & Kidd, 2004). Race is misleading as a biological category.

Instead, although race was long thought to be a valid biological category, it is actually a social construction, an idea created by society. That does not render the term meaningless: Perceived racial differences lead to discrimination, and racial identity affects cognition (see the discussion of stereotype threat in Chapter 18). But race “is a socially constructed concept, not a biological one” (Sternberg et al., 2005), and thus racial categories may change over time.

SES overlaps with ethnicity and race. When one careful study found many health differences among Americans of African, Asian, European, and Hispanic heritage living in New England, a close examination found that half of those dif- ferences could be traced to SES, not ethnicity (Krieger et al., 2005).

ethnic group People whose ancestors were born in the same region and who often share a language, culture, and religion.

race A group of people who are regarded (by themselves or by others) as genetically distinct from other groups on the basis of physical appearance.

social construction An idea that is built more on shared perceptions than on objective reality. Many age-related terms, such as childhood, adolescence, yuppies, and senior citizens are social constructions.

Heritage Aloft At least ten major ethnic groups make up China’s population of more than a billion. This man shows his grandson the multicolored lanterns displayed on Lantern Day in Hangzhou. Other nations, and other parts of China, have no Lantern Day festival, but all have special traditional cele- brations of their own.

Five Characteristics of Development 11

No Raisins? For centuries at St. Andrews University in Scotland, new students gave seniors a pound of raisins or else got dunked in a fountain. Wine has replaced raisins, and foam is sprayed instead of water—but on Raisin Monday a social construction lives on.

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Both national history and SES affect culture and hence development. For ex- ample, one cross-cultural study found that learning was stressed for middle-class preschoolers in the United States and Kenya but not for lower-class children in those two nations or for children of any SES in Brazil (Quintana et al., 2006).

The multicultural emphasis in human development requires that researchers be aware of cultural assumptions and values, respecting their power. But culture is dynamic, and people of every ethnic or economic background can accept or reject cultural values. Ethnic, racial, and economic differences do not necessarily deter- mine culture. Consider the childhood experience of poet Maya Angelou, one of many who reshaped U.S. culture during the twentieth century.

➤Answer to Observation Quiz (from page 10): They are actually using both hands. The left hand pulls the needle from underneath. Note that they work in rhythm—to keep up the pace as well as to avoid getting in each other’s way.

12 CHAPTER 1 ■ Introduction

“My Name Wasn’t Mary”

Maya Angelou was born Marguerite Johnson in 1929 into a community so racially segregated that she thought “white folks couldn’t be people because their feet were too small, their skin too white and see-throughy, and they didn’t walk on the balls of their feet the way people did—they walked on their heels like horses” (Angelou, 1970, p. 76).

Young Marguerite’s best friend was her older brother, Bailey, who gave her the nickname Maya, from “Mya sister,” as he called her. At age 10 she began to learn about White people (her “finishing school,” she called it) as an apprentice to Miss Glory, who worked as a maid for Mrs. Cullinan. Once, when Mar- guerite was serving Mrs. Cullinan and her friends:

One of the women asked, “What’s your name, girl?” It was the speckled-face one. Mrs. Cullinan said, “She doesn’t talk much. Her name is Margaret.” . . .

I smiled at her. Poor thing . . . couldn’t even pronounce my name correctly.

“She’s a sweet little thing, though.” “Well, that may be, but the name’s too long. I’d never bother

myself. I’d call her Mary if I were you.” I fumed into the kitchen. That horrible woman would never

have the chance to call me Mary because if I was starving I’d never work for her. I decided I wouldn’t pee on her if her heart was on fire. . . .

The very next day . . . Miss Glory and I were washing up the lunch dishes when Mrs. Cullinan came to the doorway, “Mary?”

Miss Glory asked, “Who?” . . . “Her name is Margaret, ma’am. Her name’s Margaret.”

“That’s too long. She’s Mary from now on. Heat that soup from last night and put it in the china tureen and Mary, I want you to carry it carefully.”

Every person I knew had a hellish horror of being “called out of his name.” It was a dangerous practice to call a Negro anything that could be loosely construed as insulting because of the cen- turies of their having been called niggers, jigs, dinges, blackbirds, crows, boots and spooks.

. . . I had to quit the job, but the problem was going to be how to do it. Momma wouldn’t allow me to quit for just any reason. . . .

Then Bailey solved my dilemma. He had me describe the contents of the cupboard and the particular plates she liked best.

Her favorite piece was a casserole shaped like a fish and the green glass coffee cups. I kept his instructions in mind, so on the next day when Miss Glory was hanging out clothes and I had again been told to serve the old biddies on the porch, I dropped the empty serving tray. When I heard Mrs. Cullinan scream, “Mary!” I picked up the casserole and two of the green glass cups in readiness. As she rounded the kitchen door, I let them fall to the tiled floor.

I could never absolutely describe to Bailey what happened next, because each time I got to the part where she fell on the floor and screwed up her ugly face to cry, we burst out laughing. She actually wobbled around on the floor and picked up shards of cups and cried “Oh, Momma. Oh, dear Gawd. It’s Momma’s china from Virginia. Oh, Momma, I sorry.”

Miss Glory came running in from the yard. . . . “You mean to say she broke our Virginia dishes. What we gone do?”

Mrs. Cullinan cried louder, “That clumsy nigger. Clumsy lit- tle black nigger.”

Old Speckled Face leaned down and asked, “Who did it, Viola? Was it Mary? Who did it?” . . .

issues and applications

Today, Everybody Knows Her Name Poet and best-selling author Maya Angelou speaks at the University of Northern Iowa about the healing and saving nature of poetry. She encouraged the members of the audience to become the “composers” of their own lives.

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Multidisciplinary Powerful forces pull scientists to specialize, to study one phenomenon in one species at one age. This tight focus can provide a deeper understanding of, for instance, the rhythms of vocalization among 3-month-old infants, or the effects of alcohol on adolescent mice, or wives’ experiences of husbands’ retirement. (Each of these has been studied extensively, and the results inform later sections of this book.)

However, the study of human development requires insight and information from a broad array of disciplines and cross-cutting topics, because each person develops simultaneously in body, mind, and spirit. Although development is often divided into three domains—biosocial, cognitive, and psychosocial—all three domains interact as part of the dynamic systems that make up a person. (Figure 1.3 provides a full definition of each domain.) For example, although giving birth is primarily biosocial because reproduction is biological, childbirth is also cogni- tive (it is a decision) and psychosocial (families and cultures vary tremendously in how newborns are treated). Placing a topic within one domain never means that that topic belongs exclusively to that domain, whether biosocial, cognitive, or psychosocial.

➤Answer to Observation Quiz (from page 10): Carolyn Whitaker, in an orange shirt, is at the far left.

Five Characteristics of Development 13

Mrs. Cullinan said “Her name’s Margaret, goddam it, her name’s Margaret.”

And she threw a wedge of broken plate at me. It could have been the hysteria which put her aim off, but the flying crockery caught Miss Glory right over her ear and she started screaming.

I left the front door wide open so all the neighbors could hear. Mrs. Cullinan was right about one thing. My name wasn’t

Mary.

[Angelou, 1970, pp. 90–93]

Maya Angelou did not follow the cultural script expected of a poor African American girl. Note, however, that her culture made

it unthinkable for her either to ask Mrs. Cullinan to call her “Marguerite” or to tell her mother she wanted to quit.

Why was Maya so unlike Miss Glory, even though they were of the same ethnicity and SES? Cohort and family history are part of the answer. Miss Glory was born 20 years earlier, a de- scendant of slaves owned by Mrs. Cullinan’s family. Mrs. Culli- nan and Old Speckled Face were also products of their culture, unaware of the “hellish horror” of renaming.

But this incident demonstrates more than the power of culture to shape perception. It also shows that people sometimes break free of the restrictions imposed by their cohort, culture, or SES.

DOMAINS OF HUMAN DEVELOPMENT

Biosocial Development

Includes all the growth and change that occur in a person’s body and the genetic, nutritional, and health factors that affect that growth and change. Motor skills—everything from grasping a rattle to driving a car—are also part of the biosocial domain. In this book, this domain is called biosocial, rather than physical or biological.

Cognitive Development

Includes all the mental processes that a person uses to obtain knowledge or to think about the environment. Cognition encompasses perception, imagination, judgment, memory, and language —the processes people use to think, decide, and learn. Education—not only the formal curriculum in schools but also informal learning— is part of this domain as well.

Psychosocial Development

Includes development of emotions, temperament, and social skills. Family, friends, the community, the culture, and the larger society are particularly central to the psychosocial domain. For example, cultural differences in “appropriate” sex roles or in family structures are part of this domain.

FIGURE 1.3

The Three Domains The division of human development into three domains makes it easier to study, but remember that very few factors belong exclusively to one domain or another. Development is not piece- meal but holistic: Each aspect of development is related to all three domains.

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Many more disciplines besides biology, psychology, and sociology contribute to our study. As one expert explains: “The study of development is a huge community enterprise that spans generations and many disciplines” (Moore, 2002, p. 74). Multiple disciplines are needed because human beings develop in many domains, in multifaceted contexts, and in diverse cultures.

Although scientists feel a powerful impulse to study just one particular thing, there is also a powerful urge toward interdisciplinary, multifaceted study.

Mirror Neurons One example of the benefit of the interdisciplinary approach to human develop- ment is shown by research on mirror neurons. This began about a decade ago, when neuroscience researchers saw that parts of a monkey’s brain responded to observed actions as if the actions were performed by the monkey itself. Thus, when one monkey watched another reach for a piece of fruit, the same brain areas were activated in both monkeys. The researchers located this response in the F5 area of the monkey premotor cortex and called those reflective brain cells mirror neurons (Rizzolatti & Craighero, 2004). Hundreds of other experiments have cor- roborated the existence of mirror neurons.

This neuroscientific discovery quickly crossed disciplines and species. Scien- tists “turned to the human brain and found neural activity that mirrors not only the movement but also the intentions, sensations, and emotions of those around us” (Miller, 2005, p. 945). As “cognitive science meets neurophysiology” (Garbarini & Adenzato, 2004, p. 100), it becomes apparent that mirror neurons affect how people learn, imitate, and think.

Mirror neurons in the human brain reflect gestures, mouth movements, and whole- body actions. When experts in dance or in martial arts watch a performance, their brains are activated as if they themselves were performing (Calvo-Merino et al., 2005).

Implications of Mirror-Neuron Research Currently, scientists in many disciplines are trying to understand the implications and limitations of this discovery (Wilson & Knoblich, 2005). Anthropologists think it might explain some aspects of cultural transmission or social organization (Adenzato & Garbarini, 2006; Morrison, 2002; Rizzolatti & Craighero, 2004); psychopathologists connect a lack of mirror neurons with autism (Williams et al., 2006); linguists think mirror neurons are relevant to language learning (Buccino et al., 2004); social psychologists wonder whether mirror neurons are one reason people understand other people’s intentions and have empathy for those in pain (Harris, 2003; Nakahara & Miyashita, 2005).

Mirror neurons are evident not only in adults but also in children and even in babies—an aspect that adds to the interest of developmentalists (Chen et al., 2004; Lepage & Théoret, 2006). New possibilities are raised that must be explored.

For example, children whose parents fight a lot learn less in school and have difficulty establishing supportive friendships or intimate relationships, even though neither parent has hit or yelled at them directly. The leading explanation (suggested by research) is that parents enmeshed in conflict are less sensitive to their children (Davies et al., 2002). The discovery of mirror neurons raises another possibility: Observing a fight may be like experiencing it.

Although scientists enjoy thinking of possibilities, they are cautious in drawing conclusions. Research on human brains is notoriously difficult. Perhaps humans merely echo monkeys; perhaps human brains respond only to hand and body move- ments, not intentions. Yet because developmental research is multidisciplinary, thousands of scientists are pursuing implications suggested by monkeys’ brains.

mirror neurons Brain cells that respond to actions performed by someone else, as if the observer had done that action. For example, the brains of dancers who wit- ness another dancer moving onstage are activated in the same movement areas as would be activated if they themselves did that dance step, because their mirror neu- rons reflect the activity.

14 CHAPTER 1 ■ Introduction

Especially for Parents Who Want Their Children to Enjoy Sports While your baby is still too young and uncoordinated to play any sports, what does the research on mirror neurons suggest you might do?

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Plasticity The term plasticity denotes two complementary aspects of development: Human traits can be molded (as plastic can be), yet people maintain a certain durability of identity (again, like plastic, which takes decades to disintegrate). Culture and upbringing affect both aspects of plasticity; so do genes and other biological influ- ences.

Plasticity provides both hope and realism—hope because change is possible, and realism because each developing person must build on what has come before. In some ways, plasticity underlies all the other four characteristics of development.

People reexamine earlier values and overcome handicaps throughout their lives, but they cannot erase them. No matter what path a life takes, the journey begins and then proceeds from some particular point, moving up, down, or straight ahead, plastic and multidirectional, connected to context and culture. I have learned all this from David.

Especially for Public Health Professionals Can immunization protect an embryo?

Five Characteristics of Development 15

a case to study My Nephew David

In the spring of 1967, in rural Kentucky, an epidemic of rubella (German measles) reached two more people: my sister-in-law, who had a sore throat for a couple of days, and her embryo, who was damaged for life. David was born in November. His survival was in doubt. He required immediate surgery for a serious heart ailment, and he was born with thick cataracts on both eyes and malformations of his thumbs, feet, teeth, and spine.

My brother is a professor and his wife is a nurse; their cul- tural and socioeconomic contexts encouraged them to seek help. Soon a consultant from the Kentucky School for the Blind told them how to help David learn. One instruction was to put him on a large rug to play. If he crawled off the rug, they should say “No” and place him back in the middle. His sense of touch would enable him to explore without bumping into walls.

Progress was slow. At age 3, David could not yet talk, chew solid food, use the toilet, coordinate his fin- gers, or even walk normally. An IQ test showed him to be severely mentally retarded. Fortunately, although deafness is common in children with rubella syn- drome, David could hear. By age 5, one eye had been destroyed, but surgery had removed the cataract on the other eye, allowing some vision.

By then, the social construction that children with severe disabilities are unteachable was changing. David’s parents enrolled him in four schools. Two were for children with cerebral palsy; one offered morning classes and the other was open in the after- noon. On Fridays, when both those schools were closed, David attended a school for the mentally re- tarded. On Sundays he went to church school, his

first “mainstreaming”—the social construction that children with special needs should learn with regular children.

At age 7, David entered public school. His motor skills were poor (he had difficulty controlling a pencil); his efforts to read were limited by his faulty vision; and his social skills were im- paired (he pinched people and laughed at the wrong times).

By age 10, David had made great strides. He had skipped a year of school and was a fifth-grader. He could read—with a magnifying glass—at the eleventh-grade level. Outside school he began to learn a second language, play the violin, and sing in the choir. He eventually went to college.

David (at right in photo below, with his brothers) now works as a translator of German texts, which he enjoys because “I like

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The five characteristics of human development lead to one conclusion: Nobody is exactly like a typical person of his or her cohort, SES, or culture. Each is influ- enced in divergent directions by many domains and contexts, whose power varies from person to person. Prediction is never precise. David will always be affected by his early damage, but he was not expected to survive, much less be able to “provide a service” to other people.

SUMMING UP

Each life is characterized by multiple changes that are multidirectional, increasing, de- creasing, zigzagging, and so on. Development is also multicontextual, with every con- text having an impact. For example, historical and socioeconomic conditions facilitate some paths through life and close off others. A multicultural approach to the study of de- velopment recognizes that culture is pervasive, affecting every action. Developmental study is also multidisciplinary, drawing on biology, psychology, education, sociology, and many other disciplines. Plasticity is always evident but never infinite: Humans are nei- ther stuck in their past nor free of it.

■

Developmental Study as a Science Because the study of development is a science, it is based on objective evidence. Because it concerns human life and growth, it is also laden with subjective percep- tions. This interplay of the objective and the subjective, of the universal and the personal, makes developmental science a challenging, fascinating, and even trans- formative study.

Adults have heartfelt opinions about how children should be raised; how emerging adults should find work or romance; whether they themselves should marry, or divorce, or have children. Opinions are subjective. Science helps us progress from opinion to truth, from wishes to actual outcomes.

Steps of the Scientific Method Scientists ask questions and seek answers. To avoid the distortions of unexamined opinions and to control the biases of personal experience, they use the scientific method. This method involves four basic steps and sometimes a fifth:

scientific method A way to answer ques- tions that requires empirical research and data-based conclusions.

16 CHAPTER 1 ■ Introduction

Not the Typical Path This woman’s lifelong ambition is to walk the 2,160-mile Appalachian Trail from Maine to Georgia. She is consider- ably more active than the average member of her cohort.

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providing a service to scholars, giving them access to something they would otherwise not have” (personal communication with David, 2007). He reported a few years ago that he is

generally quite happy, but secretly a little happier lately . . . because I have been consistently getting a pretty good vibrato when I am singing, not only by myself but in congregational hymns in church. [I asked what vibrato is; he explained:] When a note bounces up and down within a quarter tone either way of concert pitch, optimally between 5.5 and 8.2 times per second.

Amazing. David is both knowledgeable and happy, and he continues to develop his skills. He also has a wry sense of humor. When I told him that I wasn’t progressing as fast as I wanted to in revising this text, even though I was working very hard every day, he replied, “That sounds just like a certain father I know.”

The rubella damage will always be with David, limiting his development. But as his aunt, I have watched him defy pes- simistic predictions. David is a testament for plasticity: No human is entirely, inevitably restricted by past experiences.

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replication The repetition of a scientific study, using the same procedures on a similar (but not identical) group of partici- pants, in order to verify, refine, or dispute the original study’s conclusions.

scientific observation A method of testing hypotheses by unobtrusively watching and recording participants’ behavior in a sys- tematic and objective manner, either in a laboratory or in a natural setting.

1. Ask a question. On the basis of previous research or a particular theory or personal observation, pose a question. Scientists are curious about almost everything.

2. Develop a hypothesis. Reformulate and segment the question into a hypothesis, a specific prediction to be tested.

3. Test the hypothesis. Design and conduct research to provide empirical evidence (data) about the validity or falsehood of the hypothesis.

4. Draw conclusions. Use the evidence to support or refute the hypothesis. Note limitations of the research and alternative explanations.

5. Make the findings available. Publish the procedure and results in sufficient detail so that other scientists will be able to evaluate the conclusions or repli- cate the research.

Replication is the repetition of a scientific study, using similar procedures with new participants, to verify or dispute the original study’s conclusions. Science builds on science: New studies continually refine, refute, replicate, and extend the old.

Between the questions developmental scientists ask (steps 1 and 2) and the an- swers they find (steps 4 and 5) lies methodology—the specific strategies, or meth- ods, used to gather and analyze data and to test hypotheses. A research study’s validity (does it measure what it purports to measure?), reliability (would repeating the measurements produce the same results?), generalizability (do the conclusions apply beyond this study?), and usefulness (can it solve real-life problems?) affect the power of each study.

Research design can advance or undercut that power. Thus, step 3 is the pivot. Like keystones, without a good design the entire structure will collapse. Some strategies to make research valid, reliable, generalizable, and useful are described in Appendix B. In every chapter, details about the design of some research studies are provided in the margins.

Ways to Test Hypotheses Now we turn to four methods of testing hypotheses: observations, experiments, surveys, and case studies. Remember, the overall goal is to find evidence that an- swers questions as accurately as possible.

Observation Scientific observation requires the researcher to observe and record behavior systematically and objectively. Observa- tions often occur in a naturalistic setting, such as at home, in a school, or in a public park, because such settings encourage people to behave as they usually do. The observer tries to be unobtrusive so that research participants will act naturally. Observation can also occur in a laboratory or in searches of archival data.

Observation has been used to note the worldwide increase in obesity during the past few decades, which has affected children more than any other age group. Obesity rates for U.S. children are charted in Figure 1.4. One important devel- opmental question (step 1 of the scientific method) is, “Why is childhood obesity increasing?” One hypothesis (step 2) is that children today do not get as much exercise as they once did—specifically, most children no longer walk to school. Observation can be used to test this hypothesis (step 3).

hypothesis A specific prediction that is stated in such a way that it can be tested and either confirmed or refuted.

Developmental Study as a Science 17

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Can They See Her? No, and they cannot hear each other. This scientist is observing three deaf boys through a window that is a mirror on the other side. Her observations will help them learn to communicate.

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Several observers went to eight elementary schools (some rural, some urban), noting how the children arrived at school. To make sure they would catch any fluctuations by day of the week, they observed for five consecutive days. As Figure 1.5. shows, 95 percent of the children arrived by car or school bus; only 5 percent got to school under their own power, on foot or on a bicycle (Sirard et al., 2005).

Observation has one major limitation: It does not indicate what causes people to do what they do. Do children grow heavier because their parents drive them to school, or do parents drive their children because they are too heavy to walk? Is inactivity the result or the cause of overweight? Observation cannot tell us (see Research Design). An experiment can.

The Experiment The experiment is the research method that scientists use to establish cause. In the social sciences, experimenters typically give people a particular treatment, or expose them to a specific condition, and then note whether their behavior changes.

In technical terms, the experimenters manipulate an independent variable (the treatment or special condition, also called the experimental variable). They note whether the independent variable affects the specific behavior they are studying, called the dependent variable (which, in theory, depends on the inde- pendent variable). Thus, the independent variable is the new, special treatment; the dependent variable is the result of that treatment.

The purpose of an experiment is to find out whether an independent variable affects the dependent variable. Statistics are often used to analyze the results. Sometimes results are reported by effect size, to distinguish slight, moderate, or large effect. Sometimes tests of significance are used, to indicate whether the re- sults might have occurred by chance. (A finding that chance would produce the results less than 5 times in 100 is significance at the 0.05 level; 1 time in 100 is 0.01 significance.)

18 CHAPTER 1 ■ Introduction

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Source: Centers for Disease Control and Prevention, 2006, National Center for Health Statistics Web site, http://www.cdc.gov/nccdphp/dnpa/obesity/childhood/prevalence.htm; accessed February 8, 2007.

Years

FIGURE 1.4

The Obesity Epidemic The percentage of children and adolescents who are overweight or obese has more than tripled in less than 50 years. The rate of increase has been especially rapid in the past 20 years. Currently, 18 percent of the U.S. population aged 18 or younger have BMI (body mass index) values that are at or above the 95th percentile of the Centers for Disease Control’s growth charts, which is the criterion for classification as overweight.

How Children Arrived at School

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On a bike

Source: Sirard et al., 2005.

FIGURE 1.5

Why Walk When You Can Ride? An observa- tional study of eight South Carolina elemen- tary schools found that only 5 percent of the children rode their bikes or walked to school. Such a study could not explain why so few children got to school under their own steam. For that, an experiment would be needed.

Research Design Scientists: John Sirard, Barbara E. Ainsworth, Kerri L. McIver, and Russell R. Pate.

Publication: American Journal of Public Health (2005).

Participants:Total of 3,911 children at- tending 8 public elementary schools in and around Columbia, South Carolina. Schools were diverse in SES, ethnicity, and location.

Design: Observational study.Two or three observers at each school, on five consecutive school days, arrived an hour before school started and left two hours later, counting children who arrived via car, bus, bike, or on foot. Similar observations occurred in the afternoon.Weather (e.g., rain) was also noted.

Major conclusion: No matter the SES, ethnic group, urban/suburban neigh- borhood, or weather, only about 4 per- cent of the children walked to school and 1 percent rode a bike.

Comment:This is an excellent observa- tional study. However, because the schools were all in one South Carolina community, replication elsewhere is needed.

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To make sure a change in the dependent variable is caused by the independent variable, experimenters often compare two groups of participants: one that gets the special treatment and the other, similar in every relevant way, that does not. Thus, in a typical experiment (as diagrammed in Figure 1.6), two groups of partic- ipants are studied: an experimental group, which gets a particular treatment (the independent variable), and a comparison group (also called a control group), which does not.

To understand the relationship between movement and obesity, investigators (Levine et al., 2005) recruited inactive adults (they described themselves as “couch potatoes”) who agreed to wear electronic monitoring equipment to record their bodily movement. The data were automatically recorded 120 times each minute, 24 hours a day. Half the volunteers were lean, and half were overweight. The recordings revealed that the lean adults moved around in “the routines of daily life” more than the overweight adults did (Levine et al., 2005). For instance, they spent an average of nine hours a day on their feet, standing or walking; the obese ones averaged only six hours. So far this is merely observation.

Then came the experiment. Both groups were put on strict diets, the lean group to gain weight and the overweight ones to lose weight, for two months. The over- weight participants lost about 20 pounds (8 kg) each, and the lean ones gained about 10 pounds (4 kg) each. (The changes were temporary; most participants re- turned to their usual weight when they stopped dieting.) Then daily activity was measured again.

The crucial question was whether or not the overweight people moved more than before and the leaner people moved less than before now that their weight had changed. The answer was no. The monitors recorded no significant change. In fact, there was a trend toward less movement than before among the heavier people who had lost weight. This shows cause and effect: People do not move less because they are overweight; instead, they are overweight because they move less.

experiment A research method in which the researcher tries to determine the cause- and-effect relationship between two variables by manipulating one variable (called the independent variable) and then observing and recording the resulting changes in the other variable (called the dependent variable).

independent variable In an experiment, the variable that is introduced to see what effect it has on the dependent variable. (Also called experimental variable.)

dependent variable In an experiment, the variable that may change as a result of whatever new condition or situation the experimenter adds. In other words, the dependent variable depends on the inde- pendent variable.

experimental group A group of participants in a research study who experience some special treatment or condition (the inde- pendent variable).

comparison group/control group A group of participants in a research study who are similar to the experimental group in all rel- evant ways but who do not experience the experimental condition (the independent variable).

Developmental Study as a Science 19

Many participants, measured on many

characteristics, including the

dependent variable (the behavior being studied)

Experimental group

Procedure:

1. Divide participants into two groups that are matched on important characteristics, especially the behavior that is the dependent variable on which this study is focused.

2. Give special treatment, or intervention (the independent variable), to one group (the experimental group).

3. Compare the groups on the dependent variable. If they now differ, the cause of the difference was probably the independent variable.

4. Publish the results.

Special treatment (independent variable)

Significant change in the

dependent variable

No change in the dependent variable

No special treatment

(two equal groups) (predicted outcome)

Comparison (or control) group

FIGURE 1.6

How to Conduct an Experiment Observation Quiz (see answer, page 23): Does the experimental group always change?

Especially for Nurses In the field of medicine, why are experiments conducted to test new drugs and treatments?

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The Survey A third research method is the survey. Information is collected from a large num- ber of people by interview, questionnaire, or some other means. This is a quick and direct way to obtain data. However, getting valid survey data is not easy. For example, in every poll designed to predict who will win an election, the surveyed respondents must vote as they say they will, and each of them must reflect the views of the thousands of others in the voting population. Researchers know that these are both uncertainties and therefore adjust for them. The adjustment cannot be precise; many elections are “too close to call.”

Further, the wording and the sequence of questions can influence answers, and some respondents present themselves as they would like to be perceived, not as they really are. For example, in a 1998 nationwide telephone survey, 25 percent of parents said their children walked to school. The authors of the observation study described earlier believe that their finding of only 5 percent is “more accurate . . . than survey-based estimates” (Sirard et al., 2005, p. 237).

Whenever surveys ask husbands and wives, or parents and teachers, or adults and children about the same thing, the two groups’ responses differ. For example, “parents portray a much rosier picture of children’s well-being than children do of themselves” (Scott, 2000, p. 99).

To illustrate the problems that surveys can pose, note the responses among ninth graders in the United States. More than twice as many boys as girls (12 to 5 percent) say they have experienced sex before age 13 (MMWR, June 9, 2006). That is unlikely, especially since girls reach puberty sooner and their sexual part- ners are usually older, not younger, boys. Either boys exaggerate or girls underre- port their sexual activity. Surveys may not be accurate.

The Case Study A fourth research method, the case study, is an intensive study of one individual. Often the researcher begins by asking the person about past history, current think- ing, and future plans. Others (friends, family, teachers) who know the individual are also interviewed. Although some questions are prepared in advance, follow-up questions allow deeper understanding of the nuances of each particular case. A case study can begin less formally, when researchers question people they know, testing ideas in the process.

A case study can provide unanticipated insight. Jeffrey Arnett was a junior pro- fessor at the University of Missouri when he interviewed several of his students. He was surprised that the traditional markers of adulthood (marriage and vocation) did not seem important to their happiness or maturation. For example, one student named Angela

returned to Missouri a year ago after spending two years at Michigan State. . . . She loved being on her own, and she would have liked to finish her bachelor’s degree at Michigan State. However, she decided she wanted to change her major from horticulture therapy to “just plain horticulture” and when university officials resisted, she dropped out. . . .

If you look at Angela’s life right now, as it is, you might not see much in her favor. She has dropped out of college, and she is working at a job she enjoys but that doesn’t pay well and doesn’t offer much in the way of long-term prospects. She is living with a boyfriend she doesn’t respect and certainly doesn’t want to marry. Yet she is reasonably happy with her life, less for what it is now than for what she believes it will be in the future. . . . At age 21, even if she is currently adrift in many ways, all of her hopes are alive and well.

[Arnett, 2004, pp. 41–44]

Beginning with such cases, Arnett hypothesized that a new stage of life had de- veloped among 18- to 25-year-olds; he called this stage emerging adulthood.

survey A research method in which informa- tion is collected from a large number of people by interviews, written question- naires, or some other means.

case study A research method in which one individual is studied intensively.

20 CHAPTER 1 ■ Introduction

Especially for Social Scientists What are some of the benefits of cross-cultural research?

➤Response for Public Health Professionals (from page 15): No and yes. Embryos cannot be vaccinated, but immuni- zation can prevent the spread of disease and keep a pregnant woman healthy if she already has antibodies.

➤Response for Parents Who Want Their Children to Enjoy Sports (from page 14): The results of mirror-neuron research imply that people of all ages learn by observing body movements in others. This suggests that parents should make sure their baby gets many chances to watch them (or someone else) throwing balls, running, and playing sports.

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General statements cannot be proven with case studies, because each person is unique. Beyond that, collecting and interpreting the information reflects individ- ual biases and idiosyncrasies, and case studies are qualitative, not quantitative (a topic discussed later).

No developmental scientist reaches conclusions based only on a case study. At best, a case study raises hypotheses that need more formal exploration. That is ex- actly what Arnett did, and now many other research designs also find that emerging adulthood is a distinct period in the human life span (Arnett & Tanner, 2006; Settersten et al., 2005). (Emerging adulthood is discussed in Chapters 17–19.)

Studying Change over Time Developmental scientists use the methods just described—observations, experi- ments, surveys, and case studies—but they add another dimension. Their re- search must include time, or aging. Usually they accomplish this by using one of three basic designs: cross-sectional, longitudinal, or cross-sequential (summarized graphically in Figure 1.7).

Developmental Study as a Science 21

14-year-olds 10-year-olds 6-year-olds 2-year-olds

Time 1 Time 1 + 4 years Time 1 + 8 years Time 1 + 12 years Time 1 + 16 years

Time 1 Time 1 + 4 years Time 1 + 8 years Time 1 + 12 years Time 1 + 16 years

Time 1 Time 1 Time 1 Time 1 Time 1

14-year-olds 10-year-olds 6-year-olds 2-year-olds

10-year-olds 6-year-olds 2-year-olds

[4 years later] [4 years later]

CROSS-SEQUENTIAL Total time: 16 years, plus double and triple analysis

18-year-olds 14-year-olds 10-year-olds 6-year-olds 2-year-olds

[4 years later] [4 years later] [4 years later] [4 years later]

LONGITUDINAL Total time: 16 years, plus analysis

CROSS-SECTIONAL Total time: A few days, plus analysis

18-year-olds 14-year-olds 10-year-olds 6-year-olds 2-year-olds

Collect data five times, at 4-year intervals. Any differences for these individuals are definitely the result of passage of time (but might be due to events or historical changes as well as age).

Collect data five times, following the original group but also adding a new group each time. Analyze data three ways, first comparing groups of the same ages studied at different times. Any differences over time between groups who are the same age are probably cohort effects. Then compare the same group as they grow older. Any differences are the result of time (not only age). In the third analysis, compare differences between the same people as they grow older, after the cohort effects (from the first analysis) are taken into account. Any remaining differences are almost certainly the result of age.

Collect data once. Compare groups. Any differences, presumably, are the result of age.

For cohort effects, compare groups on the diagonals (same age, different years).

18-year-olds

[4 years later] [4 years later] [4 years later]

[4 years later] [4 years later] [4 years later]

[4 years later]

FIGURE 1.7

Which Approach Is Best? Cross-sequential research is the most time-consuming and most complex approach, but it also yields the best information about development. This is one reason why hundreds of scientists con- duct research on the same topics, replicating one another’s work—to gain some of the ad- vantages of cross-sequential research without having to wait all those years.

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cross-sectional research A research design that compares groups of people who differ in age but are similar in other important characteristics.

longitudinal research A research design in which the same individuals are followed over time and their development is repeat- edly assessed.

Cross-Sectional Research The most convenient, and thus most common, way to study development is with cross-sectional research. Groups of people who differ in age but share other important characteristics (such as education, SES, and ethnicity) are compared. Cross-sectional design seems simple enough, but it is difficult to ensure that the various groups being compared are similar in every important background variable except age.

In addition, historical change might affect one cohort more than another. One example would be the number of people in a cohort. Look at Figure 1.8 on page 24. Do you think that the attitudes, opportunities, or fears of the baby-boom genera- tion are affected by the fact of its huge size? If so, that is a cohort effect that might mistakenly be thought to be an age effect.

Longitudinal Research To help discover whether age itself, not cohort differences, causes a developmental change, scientists undertake longitudinal research. This approach involves col- lecting data repeatedly on the same individuals as they age. Longitudinal research

22 CHAPTER 1 ■ Introduction

Compare These with Those The apparent similarity of these two groups in gender and ethnic composition makes them candidates for cross-sectional research. Before we could be sure that any difference between the two groups is the result of age, we would have to be sure the groups are alike in other ways, such as socioeconomic status and religious affiliation. Even if two groups seem identical in everything but age, there may be unknown differences.

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is particularly useful in studying development over a long age span (Elder & Shanahan, 2006). Some valuable and surprising findings of longitudinal research are given in Table 1.2.

Longitudinal research has several drawbacks. Over time, participants may with- draw, move far away, or die. This can skew the final results if those who disappear are unlike those who stay, and usually they are. In almost every longitudinal study, people of low SES or with serious illnesses are less likely to remain involved. Often researchers cannot find them. Another problem is that participants become increasingly familiar with the questions or the goals of the study and therefore change in ways that a typical person would not.

Probably the biggest problem comes from the changing historical context. Sci- ence, popular culture, and politics alter life experiences, and those changes limit the current relevance of data collected on people born decades ago. Meanwhile, waiting for analysis of the effects of longitudinal research harms people living now. For example, dozens of chemicals, drugs, and additives might eventually cause cancer. Yet millions died of lung cancer before longitudinal research proved that 17-year-old smokers risked death at age 67.

Developmental Study as a Science 23

TABLE 1.2

Some Findings from Longitudinal Research

■ Adjustment to parents’ divorce. Negative effects linger, sometimes even into middle age, but not for everyone (Amato & Afifi, 2006; Hetherington & Kelly, 2002).

■ Preventing delinquency. Patient parenting at age 5, using conversation rather than physical punishment, decreases the likelihood of delinquency 10 years later (Pettit, 2004).

■ The effects of day care. The quality and extent of child care in infancy and early childhood are less influential than the mother’s warmth and responsiveness or coldness and rejection (NICHD, 2005).

■ The stability of personality. Personality is quite stable over the decades of adulthood. The outgoing, agreeable young adult is likely to become an outgoing, easygoing grandmother (Caspi & Shiner, 2006; McCrae & Costa, 2003).

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➤Response for Nurses (from page 19): Experiments are the only way to determine cause-and-effect relationships. If we want to be sure that a new drug or treatment is safe and effective, an experiment must be con- ducted to establish that the drug or treatment improves health.

➤Answer to Observation Quiz (from page 19): No. Note the word predicted. The hypothesis is that change will occur for the experimental group and not the control group, but the reason for doing the experiment is to discover whether that prediction does indeed come true.

➤Response for Social Scientists (from page 20): Different cultures have different ideas about child rearing. Cross-cultural research provides us with information that may be shared among various cultures and may benefit the children of those cultures.

Six Stages of Life The baby at the far left is Sarah-Maria, born in 1980 in Switzerland. Each of these photos is of a girl at another stage described in this text: infancy (age 1), the play years (age 3), the school years (age 8), adolescence (age 15), emerging adulthood (age 19), and adulthood (age 27).

Observation Quiz (see answer, page 24): Why is there no photo showing the seventh and last stage, late adulthood?

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Cross-Sequential Research Cross-sectional and longitudinal research each have advantages that compensate for the other’s disadvantages. Scientists use the two together, often with complex statistical analysis (Hartmann & Pelzel, 2005). The simplest combination is cross-sequential research (also referred to as cohort-sequential research or time- sequential research). With this design, researchers study several groups of people who are of different ages (a cross-sectional approach) and follow all of them over the years (a longitudinal approach).

A cross-sequential design can compare findings for a group of, say, 18-year-olds with findings for the same individuals at age 8, as well as with findings for groups who were 18 a decade or two earlier and groups who are 8 years old at the present (see Figure 1.7). Cross-sequential research thus allows scientists to disentangle differences related to chronological age from those related to historical period.

For example, a cross-sequential study (the Seattle Longitudinal Study) finds that some intellectual abilities (such as vocabulary) increase throughout adult- hood and others (such as speed of thinking) decline starting at about age 30 (Schaie, 2005). This study has also discovered that declines in math ability are more closely related to education than to age, a finding that neither cross- sectional nor longitudinal research could have revealed.

SUMMING UP

The scientific method is designed to help researchers answer questions objectively and honestly, with carefully gathered evidence, drawing conclusions based on the data they collect. Methods, findings, and conclusions are reported so that other scientists can build on past work and reexamine results. Researchers observe people unobtrusively, and they conduct experiments under controlled conditions. They may survey hundreds or even thousands of people or study one case in detail. To understand change over time, researchers undertake cross-sectional, longitudinal, and cross-sequential research. Every method has strengths and weaknesses.

■

cross-sequential research A hybrid research method in which researchers first study several groups of people of different ages (a cross-sectional approach) and then follow those groups over the years (a longitudinal approach). (Also called cohort-sequential research or time-sequential research.)

24 CHAPTER 1 ■ Introduction

1920 Years 2010 (projected)

0.5

Age Structure of the U.S. Population, 1920 and 2010 (population in millions)

0.7 1.2 1.7 2.2 3.0 3.6 4.7 5.8 6.3 7.8 8.1 9.1 9.3 9.4

10.6 11.4 11.6

6.1 5.7 7.2 9.1

12.1 16.7 19.5 22.1 22.6 21.0 20.1 20.2 21.4 21.7 21.3 19.7 20.7 21.4

85+

80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4

Sources: U.S. Bureau of the Census,1975 (left); U.S. Bureau of the Census, 2006 (right).

FIGURE 1.8

The Baby-Boom Population Bulge Unlike earlier times, when each generation was slightly smaller than the one that followed, each cohort today has a unique position, de- termined by the reproductive patterns of the preceding generation and by the medical ad- vances developed during their own lifetime. As a result, the baby boomers, born between 1947 and 1964, represent a huge bulge in the U.S. population. In another three decades, the leading edge of the baby-boom genera- tion, largely intact, will begin moving into the upper age group.

Especially for Future Researchers What is the best method for collecting data?

➤Answer to Observation Quiz (from page 23): All of these photos are of the same person, and she will not reach late adulthood until 2045. Longitudinal research shows con- tinuity (that happy smile) and change (her hair).

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Cautions from Science No doubt the scientific method illuminates and illustrates human development as nothing else does. Facts, hypotheses, and possibilities have all emerged that would not be known without science, and people of all ages are healthier and more capa- ble than they were in previous generations because of it. For example, infectious diseases in children, illiteracy in adults, depression in late adulthood, racism and sexism at every age are much less prevalent today than a century ago. Science is one reason.

Developmental scientists also discover changes that are not beneficial. Television, divorce, shift work, and automobiles are less benign than people first thought.

Although the benefits of science are many, so are the pitfalls. We discuss three of them: misinterpreting data, overdependence on numbers, and unethical practices.

Correlation and Causation Probably the most common mistake made in the interpretation of research is the confusion of correlation with causation. A correlation exists between two variables if one variable is more (or less) likely to occur when the other occurs. A correlation is positive if both variables tend to increase together or decrease together, negative if one variable tends to increase when the other decreases, and zero if no connection is evident. (Try taking the quiz in Table 1.3.)

To illustrate: From birth to age 9, there is a positive correlation between age and height (children grow taller as they grow older), a negative correlation be- tween age and amount of sleep (children sleep less as they grow older), and zero correlation between age and number of toes. None of these correlations is surpris- ing, but many are fascinating, such as the finding that first-born children have higher rates of asthma.

correlation A number indicating the degree of relationship between two variables, expressed in terms of the likelihood that one variable will (or will not) occur when the other variable does (or does not). A correlation is not an indication that one variable causes the other, only that the two variables are related to the indicated degree.

Cautions from Science 25

TABLE 1.3

Quiz on Correlation

Positive, Negative, Why? (Third Two Variables or Zero Correlation? Variable) 1. Ice cream sales and murder rate

2. Learning to read and number of baby teeth

3. Adult gender and number of offspring

For each of these three pairs of variables, indicate whether the correlation between them is positive, negative, or nonexistent. Then try to think of a third variable that would determine the direction of the correlation. The correct answers are printed upside down below.

Answers: 1.Positive; third variable: heat 2.Negative; third variable: age 3.Zero; each child must have a parent of

each sex; no third variable

Correlations are easy to misinterpret; people assume that one variable causes another. For instance, a longitudinal study found a correlation between teenagers’ listening to degrading music (with males depicted as sexually insatiable studs and women as mindless sex objects) and beginning to have sexual intercourse before age 20 (see Table 1.4).

Although the authors of this study say that they cannot be certain of the direction of effects, because correlation is not causation, they write that

reducing the amount of degrading sexual content in popular music, or reducing young people’s exposure to music with this type of content, could delay initiation of intercourse. . . . Intervention possibilities include reaching out to parents of adolescents, to teens, and to the recording industry.

[Martino et al., 2006, p. 338]

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The researchers assert that lyrics that glorify uncommitted sex encourage teen- agers to accept those values. Others who read this study objected. One criminal justice professor at the University of Massachusetts wrote:

The fact that sexually active kids listen to music with a sexual content should not be surprising. Did we expect they would listen to Mozart’s Requiem?

[Siegel, 2006]

With correlation, there is always the possibility that the direction is opposite to that hypothesized or that a third variable may be the underlying cause. Did that happen here? (See Research Design.) Alternative explanations from each domain for the connection between sex and music include the following:

■ Biosocial: Some teenagers have high levels of sexual hormones, which drive them to seek sexual experiences and explicitly sexual music. Sexual inter- course is the result of those hormones (a third variable).

■ Cognitive: Some teenagers seek sexual experiences, and they find music to reinforce their values (this correlation runs in the opposite direction from the authors’ assumption).

■ Psychosocial: Teenagers idolize some music stars, going to concerts, watching videos, buying posters. They emulate their idol’s lifestyle, which may include sexual activities. Listening to music is a by-product of this idolization (a third variable).

Each of these three explanations is possible, as is the original conclusion. Many other hypotheses could be formulated. Correlation indicates connection, not cause.

Quantity and Quality A second caution concerns how much scientists should rely on data produced by quantitative research (from the word quantity). Quantitative research data can be categorized, ranked, or numbered and thus can be easily translated across cultures. People are asked questions with quantifiable answers—for example, whether they agree or disagree with a statement (only two choices) or whether they do some- thing well, not well, or not at all (three choices). People are also asked to provide factual information, such as what the family income is.

Since quantities can be easily summarized, compared, charted, and replicated, many scientists prefer quantitative research. Statistics, including correlation, signifi- cance, and effect size, begin with quantitative data, which has been described as providing “rigorous, empirically testable representations” (Nesselroade & Molenaar, 2003, p. 635).

quantitative research Research that pro- vides data that can be expressed with numbers, such as ranks or scales.

26 CHAPTER 1 ■ Introduction

TABLE 1.4

Correlates of First Sexual Intercourse Before Age 20

Variable Correlation Listening to degrading sexual music 0.36*

Having friends who will approve of sex 0.39

Having parents who know where teen is –0.30

Engaging in heavy petting before age 15 0.47

Source: Martino et al., 2006. *The correlation between music and first intercourse remained significant and positive after other factors were taken into account.

➤Response for Future Researchers (from page 24): There is no best method for collecting data. The method used depends on many factors, such as the age of participants (infants can’t complete questionnaires), the question being researched, and the time frame.

Research Design Scientists: Six researchers, sponsored by the RAND Corporation.

Publication: Pediatrics (2006).This study was also reported in many news stories.

Participants:Total of 1,461 U.S. teenagers, randomly selected to be rep- resentative of all U.S. teens.

Design:Teenagers were interviewed by phone, three times over three years, and asked which of 16 popular music groups they listened to. Coders rated whether songs contained sexually de- grading lyrics. Some participants re- fused to answer questions about sex, but responses of 938 who were virgins when the study began were analyzed.

Major conclusion: Listening to degrad- ing music, but not other teen music about sex, encourages teenagers to have sexual intercourse.

Comment:This is a correlational study. The longitudinal sequence (music, then intercourse) prompted the conclusions, but others disagree about the relation- ship between the variables.

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However, by reducing data to categories and numbers, some nuances and indi- vidual distinctions are lost. Many developmental researchers use qualitative re- search (from quality), asking open-ended questions, reporting answers that are not easily translated into numbers and categories, allowing “a rich description of the phenomena of interest” (Hartmann & Pelzel, 2005, p. 163).

Consider this example. A group of kindergarteners began a playground “grass war” triggered by freshly mown grass and a boy who hit Carlotta.

The grass war now escalates, with girls and boys on both sides becoming involved. In fact, all but a few of the 5-year-old group I am observing are now in the grass war. The war continues for some time until Marina [one of the children] suggests to the children in our group that they make peace. Marina with several children behind her marches up to the boy who hit Carlotta and offers her hand in peace. The boy responds by throwing grass in Marina’s face . . . over the objections of another boy who is in his group. Marina stands her ground after being hit with the grass. The second boy pulls his friend aside and suggests that they make peace. The other boy is against the proposal, but eventually agrees and the two then shake hands with Marina. Marina then returns to our group and declares “Peace has been established.” The two groups now meet for a round of handshaking.

[Corsaro & Molinari, 2000, p.192]

Notice that this is scientific observation. The researcher did not intervene. At this point, months into his observational study, the children did not expect him to do so. His neutrality allowed him to witness young children, on their own, resolv- ing a conflict.

How would this observation be expressed in numbers? Since the weapon was grass, would this interaction be categorized as a conflict or not? A girl was the peacemaker and a boy started the fight, a gender difference that might be lost in a quantitative study. This particular incident happened in Italy. Does that matter? Without qualitative reports from many other places, we do not know if the Italian location is relevant.

Qualitative research may seem preferable, in that it reflects cultural and con- textual diversity and complexity. But it is also more vulnerable to bias and harder to replicate. Developmentalists pay attention to both kinds of research, sometimes translating qualitative research into quantifiable data, sometimes using qualitative information to suggest hypotheses for quantitative research (Hartmann & Pelzel, 2005).

Ethics in Research The most important caution for all scientists, especially those studying humans, is to ensure that their research meets the ethical standards of their field. Each aca- demic discipline and professional society involved in the study of human develop- ment has a code of ethics, or a set of moral principles, and a scientific culture that protect the integrity of research.

Ethical standards and codes have become increasingly stringent as scientists have become increasingly concerned that “research is not only valid and useful, but also ethical” (Lindsay, 2000, p. 20). Most educational and medical institu- tions have an IRB (Institutional Research Board), a group charged with permitting only ethical research. Although IRBs often slow down scientific study, some re- search done before they existed was clearly unethical, especially when children, members of minority groups, prisoners, and animals were involved (Blum, 2002; Washington, 2006).

code of ethics A set of moral principles that members of a profession or group are expected to follow.

Cautions from Science 27

qualitative research Research that con- siders qualities instead of quantities. Descriptions of particular conditions and participants’ expressed ideas are often part of qualitative studies.

Especially for People Who Have Applied to College or Graduate School Is the admis- sions process based on quality or quantity?

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Protection of Research Participants Researchers must ensure that participation is voluntary, confidential, and harm- less. In Western nations, this entails “informed consent” of the participants and, if children are involved, of the parents. In some other nations, this can require con- sent of the village elders or heads of families, as well as, of course, the research participants themselves (Doumbo, 2005).

The need to protect participants is especially obvious with children, but the same principles apply no matter what the age of the participants (Gilhooly, 2002). These include explaining the purposes and procedures of the study in advance, obtaining written permission to proceed, and allowing the participants to stop at any time.

If researchers discover something that is potentially harmful to any participant, they must stop being dispassionate, objective observers. They must intervene even though their study might be jeopardized. One researcher wanted to learn whether residential care (a form of foster care used in England for children who have spe- cial needs or whose parents cannot care for them) is humane. Here is an exchange between the researcher and a boy in residential care:

[Researcher:] Sometimes a person might talk about a situation where they have been harmed by someone. If this happens, I may need to talk to someone else, especially if it is something awful which is still happening to you, or if the person who harmed you may still be hurting someone else. I would want to be able to agree with you what should be done, and who should be told.

[Resident:] Well, that’s one part of my life I’m not going to be able to talk to you about then, isn’t it? I’m not having you deciding who to go and talk to about me.

[Morris, 1998]

As you can see, protection of participants sometimes conflicts with the goals of science. The Canadian Psychological Association makes this explicit in its code of ethics, which states that the first principle of ethical research is “respect for the dignity of persons”; the second and the third are “responsible caring” and “integrity in relationships.” Fourth is “responsibility to society.” All four principles should be observed if possible, but they are ranked in order of importance: Indi- viduals must be safeguarded before the other ethical principles can be followed (Canadian Psychological Association, 2000).

Implications of Research Results Once a study has been completed, additional ethical issues arise. Scientists are obligated to report research results as accurately and completely as possible, with- out distorting the results to support any political, economic, or cultural position.

An obvious breach of ethics is to “cook” the data, arranging the numbers so that a particular conclusion seems the only reasonable one. Deliberate falsification is rare; it leads to ostracism from the scientific community, dismissal from a teaching or research position, and, sometimes, criminal prosecution.

A more insidious danger is that research is unintentionally slanted. To prevent this, scientific training, collaboration, and replication are crucial. Numerous pre- cautions are built into methodology, several of which have already been explained. In addition, scientific reports in professional journals include (1) details of the study to allow for replication, (2) a section describing the limitations of the findings, and (3) alternative interpretations of the results.

None of this is to be taken for granted, as one researcher in animal behavior ex- plains: “Desirable modes of scientific conduct require considerable self-awareness

28 CHAPTER 1 ■ Introduction

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as well as a reaffirmation of the old virtues of honesty, skepticism, and integrity” (Bateson, 2005, p. 645). Such virtues need to be stressed for every scholar, writer, and student of child development, including you and me.

There is an additional ethical concern. “In reporting results, . . . the investigator should be mindful of the social, political, and human implications of his research” (Society for Research in Child Development, 1991). What does it mean to be “mindful” of research implications?

In one study, a group of college students who listened to Mozart before taking a cognitive test scored higher than another group who heard no music (Rauscher et al., 1993; Rauscher & Shaw, 1998). The researchers reported this finding, but they did not stress the limitations of the study. They should have been more mind- ful, because this “Mozart effect” was wildly misinterpreted: The governor of Geor- gia ordered that all babies born in his state be given a free Mozart CD in order to improve their intelligence, and Florida passed a law requiring every state-funded infant day-care center to play classical music.

In fact, the initial research did not use infants. In a later study that did use chil- dren, Mozart did not fare as well as more child-centered music (Schellenberg et al., 2007). The original results could not be replicated (Crncec et al., 2006; McKelvie & Low, 2002).

What Should We Study? Every reader of this book should consider the most important ethical concern of all: Are scientists answering the questions that are crucial to human development?

■ Do we know enough about prenatal nutrition and drugs to protect every fetus?

■ Do we know enough about the effects of poverty to enable everyone to be healthy?

■ Do we know enough about sexual behavior to eliminate AIDS, unwanted pregnancy, sex abuse, and domestic violence?

■ Do we know enough about dying to enable everyone to die with dignity?

The answer to all these questions is a resounding NO. The reasons are many, including the fact that each of these questions touches on topics so controversial that some researchers avoid them and few funders support objective studies. Yet ethical standards include more than caring for participants, ensuring confidential- ity, and reporting research honestly. Developmentalists have an obligation to study topics that are of major importance for the human family. Many people suffer because questions are unanswered or not even asked.

The next cohort of developmental scientists will build on what is known, mind- ful of what needs to be explored. That is probably the most important answer to the question posed in the fourth sentence of this chapter: “Why should you care?”

SUMMING UP

Correlations are useful, but they do not prove cause and effect. Quantitative research is more objective and easier to replicate than qualitative research, but it loses the nuances that qualitative research can reveal. Scientists follow codes of ethics to safeguard re- search participants. Scientists also must be careful to prevent misinterpretations. The most urgent issues are controversial and therefore difficult to study or to report hon- estly. That is precisely why further scientific research is needed.

■

Cautions from Science 29

➤Response for People Who Have Applied to College or Graduate School (from page 27): Most institutions of higher education emphasize quantitative data— the SAT, the GRE, GPA, class rank, and so on. Decide for yourself whether this is fairer than a more qualitative approach.

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30 CHAPTER 1 ■ Introduction

Defining Development 1. The study of human development is a science that seeks to un- derstand how people change over time. Sometimes these changes are linear—gradual, steady, and predictable—but more often they are not. Change may be small or large, caused by something seemingly insignificant, like the flap of a butterfly’s wings, or something large that affects people in unexpected ways.

2. The dynamic-systems perspective on development is now per- vasive in the study of life-span development, evident in the five characteristics of development and in every topic in this text.

3. Development is neither static nor localized; it is the result of interactions among all the systems (microsystems, macrosystems, and exosystems) that impinge on each person. Bronfenbrenner was among many who emphasized the bioecological approach to developmental study.

Five Characteristics of Development 4. Development is multidirectional, multicontextual, multicultural, multidisciplinary, and plastic. It is the product of dynamic systems, so that any change affects an interconnected system, and any person affects all the other people in a family or social group.

5. Each individual develops within unique historical, cultural, and socioeconomic contexts. Life is quite different for a low-income child in a traditional culture, for instance, than for a middle-class child in a modern, multicultural society.

6. One way to subdivide development is by domains, or general aspects of growth and change. This division can be thought of as biosocial, cognitive, and psychosocial, or even body, mind, and social self. All development affects all domains at once as the dynamic-systems perspective makes clear.

7. To understand development, it is necessary to compare many cultures and use research from many disciplines. Nevertheless, because each person has unique genes and experiences, contexts do not determine an individual’s development—but they always influence it.

8. Plasticity means that change is always possible but is never un- restricted: Childhood becomes the foundation for later growth.

Developmental Study as a Science 9. The five steps of the scientific method lead researchers to ques- tion assumptions and to gather data to test conclusions. Although far from infallible, the scientific method helps researchers avoid biases and guides them in asking questions.

10. Commonly used research methods are scientific observation, the experiment, the survey, and the case study. Each method has strengths and weaknesses. The most reliable conclusions can be drawn when various methods all reach similar conclusions and when replications using many subjects in diverse cultures confirm the results.

11. To study change over time, scientists use three research de- signs: cross-sectional research (comparing people of different ages), longitudinal research (studying the same people over time), and cross-sequential research (combining the other two methods). Each method has advantages.

Cautions from Science 12. A correlation shows that two variables are related but does not prove that one variable causes the other.

13. In qualitative research, information is recorded without being quantified, or translated into numbers. Qualitative research best captures the nuances of individual lives, but quantitative research is easier to replicate and verify.

14. Ethical behavior is crucial in all sciences. Not only must par- ticipants be protected, but results must be clearly reported and understood. Scientists must be mindful of the implications of their research.

15. Appropriate application of scientific research depends partly on the training and integrity of the scientists. The most important ethical question is whether the research that is critically needed is being designed, conducted, analyzed, and published.

SUMMARY

science of human development (p. 3)

empirical (p. 4) dynamic-systems theory (p. 5) ecological-systems approach

(p. 5) butterfly effect (p. 8) cohort (p. 9)

socioeconomic status (SES) (p. 9) ethnic group (p. 11) race (p. 11) social construction (p. 11) mirror neurons (p. 14) scientific method (p. 16) hypothesis (p. 17) replication (p. 17)

scientific observation (p. 17) experiment (p. 18) independent variable (p. 18) dependent variable (p. 18) experimental group (p. 19) comparison group/control group

(p. 19) survey (p. 20)

case study (p. 20) cross-sectional research (p. 22) longitudinal research (p. 22) cross-sequential research (p. 24) correlation (p. 25) quantitative research (p. 26) qualitative research (p. 27) code of ethics (p. 27)

KEY TERMS

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7. In what ways can surveys be considered the opposite of case studies?

8. Why would a scientist conduct a cross-sectional study?

9. Why would people refuse to participate or quit before a re- search study was finished?

10. Cite two probable correlations (positive and negative) regard- ing how you spend your time.

11. What are the disadvantages and advantages of qualitative research?

12. What is one additional question about development that should be answered?

1. What does it mean to say that the study of human develop- ment is a science?

2. Give an example of a social construction. Why is it a construc- tion, not a fact?

3. What is the difference between an ethnic group and a culture?

4. What are some cohort differences between you and your parents?

5. Why does the fact that SES and ethnic differences overlap pose a problem?

6. What are the differences between scientific observation and ordinary observation?

3. Design an experiment to answer a question you have about human development. Specify the question and the hypothesis, and then describe the experiment, including the sample size and the variables. (Look first at Appendix B.)

1. It is said that culture is pervasive but that people are unaware of it. List 30 things you did today that you might have done differ- ently in another culture.

2. How would your life be different if your parents were much higher or lower in SES than they are?

KEY QUESTIONS

APPLICATIONS

Summary 31

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2

33

Theories of Development

As we saw in Chapter 1, the science of human development beginswith questions. Among the thousands of questions are the follow-ing five, each connected to one of the five theories described inthis chapter: 1. Do early experiences—of breast-feeding or bonding or abuse—affect

adulthood? 2. Does intelligence depend on past instruction, punishment, and examples? 3. Are children and adolescents less logical than adults? 4. Does culture cause variations in adult behavior, such that, say, more

people vote in Ontario than in Ohio? 5. If a newborn’s parents are alcoholics, should that child never drink?

For every answer, more questions arise: Why or why not? When and how? And the most crucial question of all: So what?

What Theories Do Each of the five questions listed above is answered yes by one of the five major theories—in order: (1) psychoanalytic theory, (2) behaviorism, (3) cognitive theory, (4) sociocultural theory, and (5) epigenetic theory. Each question is answered less affirmatively by several other theories, perhaps with “not nec- essarily” or “only sometimes” or even “never.”

To find and frame the critical questions regarding development, and then to answer them, we must organize thousands of observations. For that, we need a theory.

A developmental theory is a systematic statement of principles and generalizations that provides a coherent framework for understanding how and why people change as they grow older. Developmental theorists “try to make sense out of observations . . . [and] construct a story of the human jour- ney from infancy through childhood or adulthood” (P. H. Miller, 2002, p. 2). Theories connect facts and observations with patterns and explanations, weaving the details of life into a meaningful whole.

As an analogy, imagine building a house. A person could have a heap of lumber, nails, and other materials, but without a blueprint or construction drawings, the heap cannot become a house. Observations of human devel- opment are essential raw materials, but theories are needed to put them

CHAPTER OUTLINE

� What Theories Do

� Grand Theories

Psychoanalytic Theory Behaviorism THINKING LIKE A SCIENTIST:

What’s a Mother For? Cognitive Theory

� Emergent Theories

Sociocultural Theory Epigenetic Theory IN PERSON: My Beautiful, Hairless Babies

� What Theories Contribute

The Nature–Nurture Controversy No Answers Yet

developmental theory A group of ideas, assumptions, and generalizations that interpret and illuminate the thousands of observations that have been made about human growth. In this way, developmental theories provide a framework for explain- ing the patterns and problems of development.

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together. As Kurt Lewin (1943) once quipped, “Nothing is as practical as a good theory.”

To be more specific:

■ Theories lead to pivotal hypotheses, each of which becomes “a direct test of a question” (Salkind, 2004, p. 14).

■ Theories generate discoveries. ■ Theories offer practical guidance. If a 5-year-old shouts “I hate you!” at his

father, the man’s reaction (laughing, ignoring, slapping, or asking “Why?”) de- pends on his theory of child development (whether or not he knows it).

Hundreds of theories pertain to developmental science. A few (the psycho- analytic, behaviorist, and cognitive theories) are called grand theories because they describe universal processes and development throughout the entire life span. They offer “a powerful framework for interpreting and understanding . . . change and development of all individuals” (Renninger & Amsel, 1997, p. ix). Some (the sociocultural and epigenetic theories) are emergent theories; they may become the new systematic and comprehensive theories of the future.

Literally thousands of theories are minitheories, about some part of develop- ment, perhaps only one age or one domain. For example, one minitheory concerns racial identity (theory of racial socialization), another, friendships in late adult- hood (theory of socioemotional selectivity). Minitheories are not presented in this chapter, but remember that, no matter what interests you, theories are a useful way to organize and select your observations.

The distinction between grand and emergent theories is best understood by re- ferring to the multidisciplinary perspective, first noted in Chapter 1. The grand theories of human development originated in the discipline of psychology, while observations and explanations originating in history, biology, sociology, and anthro- pology led to the emergent theories.

Historical events (notably, increasing globalization and immigration) and genetic discoveries (for example, from the International Hapmap Project, finding alternate versions of genes) highlight the need for the cultural and genetic approaches of the new theories. Two emergent theories (sociocultural and epigenetic) are not yet as coherent as the grand theories, but they are broader than the traditional grand the- ories that draw only on psychology.

SUMMING UP

Theories are useful—even essential—for scientific study. They provide a framework for organizing the thousands of observations that may be made about any aspect of devel- opment. This chapter describes three grand theories—psychoanalytic, behaviorist, and cognitive—and two emergent theories—sociocultural and epigenetic. Throughout the remaining chapters of the book, these five theories will repeatedly be referred to (see the Subject Index entry for each theory). Several minitheories will also be cited.

■

Grand Theories In the first half of the twentieth century, two opposing theories—psychoanalytic theory and behaviorism (also called learning theory)—began as general theories of psychology and later were applied specifically to human development. By mid- century, cognitive theory had emerged, and it gradually became the dominant seedbed of research hypotheses. All three theories are “grand” in that they are comprehensive, enduring, and widely applied (McAdams & Pals, 2006).

grand theories Comprehensive theories of psychology, which have traditionally inspired and directed psychologists’ thinking about child development. Psychoanalytic theory, behaviorism, and cognitive theory are all grand theories.

emergent theories Theories that bring together information from many disciplines in addition to psychology and that are becoming comprehensive and systematic in their interpretations of development but are not yet established and detailed enough to be considered grand theories.

34 CHAPTER 2 ■ Theories of Development

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Psychoanalytic Theory Inner drives and motives, many of them irrational, originating in childhood, and unconscious (hidden from awareness), are crucial concepts in psychoanalytic theory. These basic underlying forces are thought to influence every aspect of thinking and behavior, from the smallest details of daily life to the crucial choices of a lifetime.

Freud’s Ideas Psychoanalytic theory originated with Sigmund Freud (1856–1939), an Austrian physician who treated patients suffering from mental illness. He listened to their accounts of dreams and fantasies, thought deeply about Greek drama and “primitive” art, and constructed an elabo- rate, multifaceted theory.

According to Freud, development in the first six years oc- curs in three stages, each characterized by sexual pleasure centered on a particular part of the body. In infancy, the erotic body part is the mouth (the oral stage); in early child- hood, it is the anus (the anal stage); in the preschool years, it is the penis (the phallic stage), a source of pride and fear among boys and a reason for sadness and envy among girls. Then comes latency and, beginning at adolescence and last- ing lifelong, the genital stage (see Table 2.1).

Freud maintained that at each stage, sensual satisfaction (from stimulation of the mouth, anus, or penis) is linked to major developmental needs and challenges. Each stage in- cludes its own potential conflicts. For instance, according to Freud, how people experience and resolve these conflicts— especially those related to weaning, toilet training, and sexual pleasure—determine personality patterns, because “the early stages provide the foundation for adult behavior” (Salkind, 2004, p. 125).

A psychoanalytic interpretation would be that adults may be stuck in uncon- scious struggles rooted in a childhood stage if they smoke cigarettes (stuck in the oral stage) or keep careful track of money (anal) or are romantically attracted to much older partners (phallic). For all of us, childhood fantasies and memories re- main powerful lifelong. If you have ever wondered why lovers call each other “baby” or why many people refer to their spouse as their “old lady” or “sugar

psychoanalytic theory A grand theory of human development that holds that irra- tional, unconscious drives and motives, often originating in childhood, underlie human behavior.

Grand Theories 35

Freud at Work In addition to being the world’s first psychoanalyst, Sigmund Freud was a prolific writer. His many papers and case histories, primarily descriptions of his patients’ bizarre symptoms and unconscious sexual urges, helped make the psychoanalytic perspective a dominant force for much of the twentieth century.AK

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Childhood Sexuality The girl’s interest in the statue’s anatomy may just reflect simple curiosity, but Freudian theory would maintain that it is a clear manifestation of the phallic stage of psychosexual development, when girls are said to feel deprived because they lack a penis.

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daddy,” then Freud’s theory provides an explanation: The parent–child relationship is the model for all intimacy.

This idea has been developed by researchers interested in attachment theory, building on the idea that early relationships between parent and child echo throughout life. These researchers have found that “infant attachment history” predicts numerous aspects of intimate relationship functioning (Sroufe et al., 2005, p. 203), including romance (Mikulincer & Goodman, 2006).

Erikson’s Ideas Many of Freud’s followers became famous theorists themselves. The most notable in the field of human development was Erik Erikson (1902–1994).

Erikson never knew his biological father. He spent his childhood in Germany, his adolescence wandering through Italy, and his young adulthood in Austria, working with Freud’s daughter Anna. He married an American, and he fled to the United States just before World War II. Once in the United States, he continued his interest in various cultures: He studied Harvard students, Boston children at play, and Native Americans.

As you can see, Erikson was interested in cultural diversity, social change, and psychological crises throughout the life span. For example, he wrote a massive case study of Mahatma Gandhi (Erikson, 1969), born in India, educated in

36 CHAPTER 2 ■ Theories of Development

TABLE 2.1

Comparison of Freud’s Psychosexual and Erikson’s Psychosocial Stages

Approximate Age Freud (Psychosexual) Erikson (Psychosocial) Oral Stage The lips, tongue, and gums are the focus of pleasurable sensations in the baby’s body, and sucking and feeding are the most stimulating activities.

Anal Stage The anus is the focus of pleasurable sensations in the baby’s body, and toilet training is the most important activity.

Phallic Stage The phallus, or penis, is the most important body part, and pleasure is derived from genital stimulation. Boys are proud of their penises, and girls wonder why they don’t have one.

Latency Not really a stage, latency is an interlude during which sexual needs are quiet and children put psychic energy into conventional activities like schoolwork and sports.

Genital Stage The genitals are the focus of pleasurable sensations, and the young person seeks sexual stimulation and sexual satisfaction in heterosexual relationships.

Freud believed that the genital stage lasts throughout adulthood. He also said that the goal of a healthy life is “to love and to work.”

Birth to 1 year

1–3 years

3–6 years

6–11 years

Adolescence

Adulthood

Trust vs. Mistrust Babies either trust that others will care for their basic needs, including nourishment, warmth, cleanliness, and physical contact, or mistrust the care of others.

Autonomy vs. Shame and Doubt Children either become self-sufficient in many activities, including toileting, feeding, walking, exploring, and talking, or doubt their own abilities.

Initiative vs. Guilt Children want to undertake many adultlike activities or fear the limits set by parents and feel guilty.

Industry vs. Inferiority Children busily learn to be competent and productive in mastering new skills or feel inferior and unable to do anything well.

Identity vs. Role Confusion Adolescents try to figure out “Who am I?” They establish sexual, political, and vocational identities or are confused about what roles to play.

Intimacy vs. Isolation Young adults seek companionship and love or become isolated from others because they fear rejection and disappointment.

Generativity vs. Stagnation Middle-aged adults contribute to the next generation through meaningful work, creative activities, and/or raising a family, or they stagnate.

Integrity vs. Despair Older adults try to make sense out of their lives, either seeing life as a meaningful whole or despairing at goals never reached.

Especially for Adults Who Blame Their Parents Freud believed that every emotional or personality problem adults might have was caused by poor parenting in the first five years of life. Do you think this is true for you?

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Britain, a lawyer in South Africa, and leader of the nonviolent revolution that helped India gain independence.

Erikson described eight developmental stages, each characterized by a chal- lenging developmental crisis (summarized in Table 2.1). Although Erikson named two polarities at each stage, he recognized a wide range of outcomes between these opposites. For most people, development at each stage leads to neither ex- treme but to something in between.

As you can see from Table 2.1, Erikson’s first five stages follow the same se- quence and include the core concepts of Freud’s stages. Erikson, like Freud, be- lieved that the problems of adult life echo the conflicts of childhood. For example, an adult who has difficulty establishing a secure, mutual relationship with a life partner may never have resolved the first crisis of early infancy, trust versus mis- trust. However, Erikson’s stages differ significantly from Freud’s: They emphasize family and culture, not sexual urges, and they continue throughout adulthood.

For Erikson, the resolution of each crisis depends on the interaction between the individual and the social environment as the family and culture construct it. In the stage of initiative versus guilt, for example, children between ages 3 and 6 often want to undertake activities that exceed their abilities or the limits set by their parents. They jump into swimming pools, put their shirts on backwards, make cakes with their own recipes. Such initiatives may lead to pride or failure, with failure perhaps producing guilt.

The outcome of the initiative-versus-guilt crisis depends on how the child seeks independence, how the parents react, and what the society expects. As an example, some families and cultures encourage 5-year-olds to be assertive, seeing them as creative spirits, whereas others call them “rude” or “fresh” if they insist on getting their own way.

Children internalize, or accept, such responses from their parents, peers, and cultures, and those internalized reactions persist throughout life. Even in late adulthood, one person may be bold and outspoken while another fears saying the wrong thing because these two resolved their initiative-versus-guilt stage in oppo- site ways.

Both Erikson and Freud emphasize the first years of life, and both consider early conflicts when they seek to explain later problems. This is the main criticism of psychoanalytic theory, especially from behaviorists, as you will now see.

Grand Theories 37

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What’s in a Name?—Erik Erikson As a young man, this neo-Freudian changed his last name to the one we know him by. What do you think his choice means? (See the caption to the next photograph.)

Who Are We? The most famous of Erikson’s eight crises is the identity crisis, during ado- lescence, when young people find their own answer to the question “Who am I?” Erikson did this for himself by choosing a last name that, with his first name, implies “son of my- self” (Erik, Erik’s son). These children in north- ern Ireland may be smoking because their search for identity is taking place in a socio- cultural context that allows an unhealthy path toward adulthood.GID

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Especially for Teachers Your kindergartners are talkative and always moving. They almost never sit quietly and listen to you. What would Erik Erikson recommend?

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Behaviorism The second grand theory, behaviorism, arose in direct opposition to the psycho- analytic emphasis on unconscious, hidden urges (described in Table 2.2). Such urges could not be quantified, and the raw material for Freud’s theories came from his patients and Greek drama, which did not seem scientific. Early in the twenti- eth century, John B. Watson (1878–1958) argued that if psychology was to be a science, psychologists should examine only what they could see and measure: be- havior, not thoughts and hidden urges. In Watson’s words:

Let us limit ourselves to things that can be observed, and formulate laws con- cerned only with those things. . . . We can observe behavior—what the organism does or says.

[Watson, 1924/1998, p. 6]

According to Watson, if psychologists focus on behavior, they will realize that anything can be learned. He wrote:

Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select—doctor, lawyer, artist, merchant chief, and yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race.

[Watson, 1924/1998, p. 82]

Other psychologists, especially in the United States, thought that Watson’s em- phasis on learning was insightful. They found it difficult to use the scientific method to verify the unconscious motives and drives that Freud described (Cairns & Cairns, 2006). Some developed behaviorism to study actual behavior, objec- tively and scientifically.

Laws of Behavior For every individual at every age, from newborn to centenarian, behaviorists seek the overarching laws that govern how simple actions and environmental responses shape such complex actions as reading a book or making a family dinner. Behav- iorists are also called learning theorists, because they believe that all behavior is learned step by step. Then they become habits, repeated without much thought, which is true for at least half of what we do (Neal et al., 2006).

behaviorism A grand theory of human devel- opment that studies observable behavior. Behaviorism is also called learning theory because it describes the laws and processes by which behavior is learned.

38 CHAPTER 2 ■ Theories of Development AR

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An Early Behaviorist John Watson was an early proponent of learning theory. His ideas are still influential and controversial today.

TABLE 2.2

Psychoanalytic Theory vs. Behaviorism

Area of Disagreement Psychoanalytic Theory Behaviorism Emphasizes unconscious wishes and urges, unknown to the person but powerful all the same

Holds that observable behavior is a symptom, not the cause—the tip of an iceberg, with the bulk of the problem submerged

Stresses that early childhood, including infancy, is critical; even if a person does not remember what happened, the early legacy lingers throughout life

Holds that most aspects of human development are beyond the reach of scientific experiment; uses ancient myths, the words of disturbed adults, dreams, play, and poetry as raw material

The unconscious

Observable behavior

Importance of childhood

Scientific status

Holds that the unconscious not only is unknowable but also may be a destructive fiction that keeps people from changing

Looks only at observable behavior—what a person does rather than what a person thinks, feels, or imagines

Holds that current conditioning is crucial; early habits and patterns can be unlearned, even reversed, if appropriate reinforcements and punishments are used

Is proud to be a science, dependent on verifiable data and carefully controlled experiments; discards ideas that sound good but are not proven

➤Response for Adults Who Blame Their Parents (from page 36): Scientists vehemently disagree about Freud. Some think he was an insightful genius; others believe he was a deluded drug addict. For you, the relevant question might be: If someone else had the same childhood you did, would he or she be just like you?

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The specific laws of learning apply to conditioning, the processes by which responses become linked to particular stimuli. There are two types of condi- tioning: classical and operant.

More than a century ago, Russian scientist Ivan Pavlov (1849–1936), after winning the Nobel Prize for his work on animal digestion, noted that his experi- mental dogs drooled not only when they saw and smelled food but also when they heard the footsteps of the attendants who brought the food. This observation led Pavlov to perform his famous experi- ments, conditioning dogs to salivate when they heard a bell.

Pavlov began by ringing the bell just before presenting food. After a number of repetitions of the bell-then-food sequence, dogs began salivating at the bell’s sound even when there was no food. This simple experiment demonstrated classical conditioning (also called respondent conditioning), by which a person or animal is conditioned to associate a neutral stimulus with a meaningful stimu- lus, gradually responding to the neutral stimulus in the same way as to the mean- ingful one.

The most influential North American behaviorist was B. F. Skinner (1904– 1990). Skinner agreed with Watson that psychology should focus on the scientific study of behavior, and he agreed with Pavlov that classical conditioning explains some behavior. However, Skinner believed that another type of conditioning, operant conditioning (also called instrumental conditioning), is often crucial, especially in complex learning. In operant conditioning, animals behave in some way and a response occurs. If the response is useful or pleasurable, the animal is likely to repeat the behavior. If the response is painful, the animal is not likely to repeat the behavior.

Pleasant consequences are sometimes called “rewards,” and unpleasant conse- quences are sometimes called “punishments.” Behaviorists hesitate to use those words, however, because what people commonly think of as a punishment can actually be a reward, and vice versa. For example, parents punish their children by withholding dessert, by spanking them, by not letting them play, by speaking harshly to them, and so on. But a particular child might, for instance, dislike the dessert, so being deprived of it is actually a reward, not a punishment. Another child might not mind a spanking, especially if he or she craves parental attention. In that family, the intended punishment (spanking) is actually a reward (attention).

Any consequence that follows a behavior and makes the person (or animal) likely to repeat that behavior is called a reinforcement, not a reward. Once a behavior has been conditioned, humans and other creatures will do it even if reinforcement occurs only occasionally. Similarly, punishment might make a creature never repeat a certain action. Almost all daily behavior, from socializing with others to earning a paycheck, can be understood as a result of past operant conditioning, according to many behaviorists.

For that reason, early parenting is considered crucial, because it teaches habits that may endure. For instance, if parents want their child to share, when their baby hands them a gummy, half-eaten cracker, they should take the gift with ap- parent delight and then return it, smiling. Adults should never pull at a toy a child

conditioning According to behaviorism, the processes by which responses become linked to particular stimuli and learning takes place. The word conditioning is used to emphasize the importance of repeated practice, as when an athlete gets into physical condition by training for a long time.

classical conditioning The learning process that connects a meaningful stimulus (such as the smell of food to a hungry animal) with a neutral stimulus (such as the sound of a bell) that had no special meaning before conditioning. Also called respon- dent conditioning.

operant conditioning The learning process by which a particular action is followed by something desired (which makes the person or animal more likely to repeat the action) or by something unwanted (which makes the action less likely to be repeated). Also called instrumental conditioning.

reinforcement A technique for conditioning behavior in which that behavior is followed by something desired, such as food for a hungry animal or a welcoming smile for a lonely person.

Grand Theories 39

A Contemporary of Freud Ivan Pavlov was a physiologist who received the Nobel Prize in 1904 for his research on digestive processes. It was this line of study that led to his discov- ery of classical conditioning.

Observation Quiz (see answer, page 40): In appearance, how is Pavlov similar to Freud, and how do both look different from the other theorists pictured?

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➤Response for Teachers (from page 37): Erikson would note that the behavior of 5- year-olds is affected by their developmental stage and by their culture. Therefore you might design your curriculum to accommodate active, noisy children.

Especially for Teachers Same problem as previously (talkative kindergartners, but what would a behaviorist recommend?

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is holding, encouraging the child to hold tight. Strangers sometimes did that with my children, teaching possessiveness—a lesson I didn’t want my children to learn.

The science of human development has benefited from behaviorism. The the- ory’s emphasis on the antecedents and consequences of observed behavior led re- searchers to realize that many actions that seem to be genetic, or to result from deeply rooted emotional problems, are actually learned. And if something is learned, it can be unlearned. No longer are “the events of infancy and early child- hood . . . the foundation for adult personality and psychopathology,” as psychoana- lysts believed (Cairns & Cairns, 2006, p. 117). People can change, even in old age.

That makes behaviorism a very hopeful theory. It encourages scientists to find ways to eliminate destructive behaviors, among them temper tantrums, phobias, and addictions. Many teachers, counselors, and parents use behaviorist tech- niques to break undesirable habits and teach new behaviors (Kazdin, 2001). Tantrums cease, phobias disappear, addicts recover, and so on, although not al- ways as easily as the theory predicts.

Like all good theories, both behaviorism and psychoanalytic theory have led to hypotheses and scientific experiments, such as those described in the following feature.

40 CHAPTER 2 ■ Theories of Development

thinking like a scientist What’s a Mother For?

Why do children love their mothers, even if their mothers are mean or unresponsive? Is it because their mothers fed or com- forted them when they were infants? To explore such questions, scientists need theories, and then data to disprove or confirm their theories.

Both behaviorism and psychoanalytic theory originally hy- pothesized that mothers are loved because they satisfy the new- born’s hunger and sucking needs. In other words, “the infant’s attachment to the mother stemmed from internal drives which triggered activities connected with the libations of the mother’s breast. This belief was the only one these two theoretical groups ever had in common” (C. Harlow, 1986). During infancy, moth- ers were for feeding, and not much else.

Physicians in every hospital were taught that germs caused disease, so they assumed that mothers who kissed and hugged their babies would “spoil” and sicken them. As a consequence, a hundred years ago, orphanages and hospitals kept babies clean and well fed but forbade caregivers to caress them, because “human contact was the ultimate enemy of health” (Blum, 2002, p. 35).

In the 1950s, Harry Harlow (1905–1981), a psychologist who studied learning in monkeys, observed something surprising.

We had separated more than 60 of these animals from their mothers 6 to 12 hours after birth and suckled them on tiny bot- tles. . . . During the course of our studies we noticed that the laboratory-raised babies showed strong attachment to the folded gauze diapers which were used to cover the . . . floor of their cages.

[Harlow, 1958, p. 673 ]

In fact, the infant monkeys seemed more attached to the cloth diapers than to their bottles. This was contrary to the two prevailing theories, since psychoanalytic theory predicted that infants would love whatever satisfied their oral needs and be- haviorism predicted that infants would cherish whatever pro-

Clinging to “Mother” Even though it gave no milk, this “mother” was soft and warm enough that infant monkeys spent almost all their time holding on to it. Many infants, some children, and even some adults cling to a familiar stuffed animal when life becomes frightening. According to Harlow, the reasons are the same: All pri- mates are comforted by something soft, warm, and familiar.

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➤Response for Teachers (from page 39): Behaviorists believe that anyone can learn anything. If your goal is quiet, attentive children, begin by reinforcing a moment’s quiet or a quiet child, and soon all the children will be trying to remain attentive for several minutes at a time.

➤Answer to Observation Quiz (from page 39): Both are balding, with white beards. Note also that none of the other theorists in this chapter have beards—a cohort difference, not an ideological one.

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Grand Theories 41

vided reinforcing food. Motherless monkeys should love their bottles, not their floorcloths.

Harlow set out to make a “direct experimental analysis” of human love via his monkeys because he believed that “the basic processes relating to affection, including nursing, contact, cling- ing, and even visual and auditory exploration, exhibit no funda- mental differences in the two species” (H. Harlow, 1958). Harlow was troubled that few psychologists recognized the cru- cial role of physical contact—cuddling, soothing, hugging, and so on—for all social species, including monkeys and humans.

Harlow raised eight infant monkeys, each in a cage with no other animals but with two “surrogate” (artificial) mothers, both mother-monkey size. One surrogate was made of bare wire and the other was covered by soft terrycloth, with a face designed to be ugly—two red bicycle reflectors for eyes and a strip of green for a mouth—but otherwise “soft, warm, and tender, a mother with infinite patience.” Four of the baby monkeys were fed by a bottle stuck through the chest of the cloth “mother,” the other four by a bottle on the wire “mother” (see Research Design).

Harlow measured how much time each infant monkey spent clinging to each of the two surrogates. The monkeys who had a cloth, milk-providing mother clung to it and ignored the wire mother; this was to be expected, since feeding was connected with mothering. However, even the four babies that fed from the wire mother clung to the cloth mother, going to the wire mother only when hunger compelled them (see Figure 2.1). In short, no attachment to, or love for, the nourishing wire mother could be observed, but the cloth mother had the infants’ affec- tion whether or not it provided food. The answer to the question “Does food equal mother love?” was a resounding “No!”

The next question was whether the cloth mothers might re- assure infants when frightening events occurred, just as a live mother does. Harlow devised another experiment. He put an

unfamiliar mechanical toy into each infant’s cage. The monkeys immediately sought comfort from their cloth mother, clinging to the soft belly with one hand and then timidly exploring the new object with the other.

The wire mother provided no such reassurance. Monkeys con- fronted by the same mechanical toy with access only to their wire mother were terrified—freezing, screaming, shivering, hiding,

Hours per day

Time on Cloth Mother Cloth-fed Wire-fed

Time on Wire Mother Cloth-fed Wire-fed

Time Infant Monkeys Spent on Cloth and Wire Mothers

18

15

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6

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Mean age (in days)

Source: Adapted from H. Harlow, 1958.

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FIGURE 2.1

Softer Is Better During the first three weeks of Harlow’s experiment, the infant monkeys developed a strong preference for the cloth- covered “mothers.” That preference lasted throughout the experiment, even among the monkeys who were fed by a wire-covered mother.

Observation Quiz (see answer, page 44): At five days, how much time did the wire-fed monkeys (compared with the cloth-fed monkeys) spend on the cloth mothers?

Research Design Scientists: Harry Harlow and many others.

Publication: Reprinted in Learning to Love:The Selected Papers of H. F. Harlow (1986), edited by Clara Mears Harlow.

Subjects: Eight infant rhesus monkeys born in Harlow’s laboratory.

Design:The monkeys were raised from birth in separate cages, each with two “surrogate mothers”: one made of bare wire and the other of wire covered with terrycloth. Half the monkeys were fed by a bottle stuck onto the wire mother, the other half by a bottle stuck onto the cloth mother. Harlow recorded how much time the monkeys spent feeding from and clinging to each mother.

Major conclusion: Monkeys, and presumably all primate infants, need “contact comfort,” the warm and soft reassur- ance of a mother’s touch.

Comment: Many design problems are apparent: too few subjects, ethical questions about treatment of animals, and uncertainty about whether data on lab-reared, socially isolated rhesus monkeys applies to humans, or even to other primates in nature. However, the results of this ex- periment were so dramatic that it has been replicated and revised by dozens of other researchers. Harlow’s research revolutionized child care.

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Social Learning Originally, behaviorists believed that all behavior arose from a chain of learned re- sponses, the result of classical and operant conditioning. One refinement of be- haviorism came from evidence (from humans as well as monkeys) that all social creatures appreciate another’s touch, warmth, reassurance, and example.

This revision is called social learning theory (see Figure 2.2). Its central premise is that humans can learn from observing others, without personally expe- riencing any reinforcement. We learn from other people because we are social be- ings. We grow up in families, we learn from friends and teachers, we love and hate and admire other people—even when we wish we were more independent.

social learning theory An extension of behaviorism that emphasizes the influence that other people have over a person’s behavior. Even without specific reinforce- ment, every individual learns many things via observation and imitation of other people.

42 CHAPTER 2 ■ Theories of Development

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Social Learning in Action Social learning validates the old maxim “Actions speak louder than words.” If the moments here are typical for each child, the girl on the left is likely to grow up with a ready sense of the importance of this particular chore of infant care. Unfortunately, the girl on the right with a candy “cigarette” may smoke tobacco like her mother—even if her mother warns her not to do so.

Observation Quiz (see answer, page 46): What shows that these children imitate their parents? DA

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urinating. Harlow concluded that mothering is not primarily about feeding but about what he called “contact comfort” or “love.”

Later Harlow’s students discovered that mother love involves more than contact. To become psychologically healthy adults, infant monkeys (and humans as well) need interaction with an- other living, responsive creature (who could be either sex) (Blum, 2002).

Harlow’s experiments are a classic example of the use of the- ories. Although aspects of both behaviorism and psychoanalytic theory were disproved, that is not the most significant point. Re- member, theories are meant to be useful, not necessarily true. Because Harlow knew what theories predicted about love and

comfort, he was intrigued by the baby monkeys’ attraction to the gauze diapers covering the floors of their cages. That led to closer observation, a hypothesis, a clever series of experiments, and some amazing results.

This research revolutionized the treatment of sick or mother- less children. Even very tiny, fragile preterm infants now have contact with their parents, typically including very gentle touch—and their chances of survival are better because of it (see Chapter 4).

Today’s mothers do much more cuddling and infants do much less crying than their predecessors did a century ago be- cause one creative scientist contrasted theory and observations, performing ingenious experiments to test a hypothesis.

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An integral part of social learning is modeling, in which people ob- serve what someone else does and then copy it. Even hairstyles or dance steps are copied from others—which explains why they change with each generation. Modeling is far more complex than simple imitation, because people model only some actions, of some individuals, in some contexts. For example, you may know people who, as children, were never personally abused but saw their parents hit each other. Some be- come adults who are violent with their romantic partners, while others are careful to avoid such behavior. These opposite responses support so- cial learning theory; they show the continuing impact of the original example. One child identified with the abuser and the other with the victim, thus, each learned a different lesson. Generally, modeling is likely when the observer is uncertain or inexperienced and when the model is admired, powerful, nurturing, or similar to the observer (Bandura, 1986, 1997).

As this example shows, social learning is connected to perceptions and interpre- tations. It is also related to self-understanding, social reflection, and self-efficacy, a feeling of self-confidence that people develop when they have high aspirations and notable achievements (Bandura, 2006).

Self-efficacy explains a paradox found in recent research: Parents who do not believe in their own efficacy and who think their babies are strong-willed are stricter and less responsive than other parents. Why? The explanation from social learning theory is that their own parents probably never let them develop a strong sense of themselves, so they still feel ineffective (Guzell & Vernon-Feagans, 2004). Their parents probably punished them when they tried to assert them- selves. Their lack of self-efficacy and their parents’ example lead them to be overly controlling with their children.

Current versions of social learning theory incorporate elements of two of the other major theories, cognitive theory and sociocultural theory (Bandura, 2006).

Cognitive Theory The third grand theory, cognitive theory, emphasizes the structure and develop- ment of thought processes. According to this theory, thoughts and expectations profoundly affect attitudes, beliefs, values, assumptions, and actions. Cognitive theory has dominated psychology since about 1980 and has branched into many versions, each adding insights about human development. A major extension of cognitive theory is information-processing theory, which focuses on the step-by-step activation of various parts of the brain, as described in Chapter 6 (brain function- ing is explained in Chapter 5).

The original cognitive theorist was the Swiss scientist Jean Piaget (1896–1980), who was trained in the natural sciences and studied shellfish. Piaget became inter- ested in the science of human behavior when he got a job in Paris, field-testing questions for a standardized IQ test. Although he was hired to find the age at which children could answer various questions correctly, the incorrect answers and the thinking behind them caught his attention. How children think is more revealing, Piaget concluded, than what they know; process, not product, is important.

Piaget’s interest in cognitive development grew as he observed his own three children. He realized that babies are much more curious and thoughtful than other psychologists had imagined. Later he studied hundreds of schoolchildren.

From this work Piaget developed the central thesis of cognitive theory: How people think changes with time and experience, and thought processes always af- fect behavior. Piaget maintained that cognitive development occurs in four major periods, or stages: sensorimotor, preoperational, concrete operational, and formal op- erational (see Table 2.3). These periods are age-related, and, as you will see in

Grand Theories 43

modeling The central process of social learn- ing, by which a person observes the actions of others and then copies them.

self-efficacy In social learning theory, the belief of some people that they are able to change themselves and effectively alter the social context.

cognitive theory A grand theory of human development that focuses on changes in how people think over time. According to this theory, our thoughts shape our atti- tudes, beliefs, and behaviors.

Learning occurs through:

Classical conditioning Through association, neutral stimulus becomes conditioned stimulus. Operant conditioning Through reinforcement, weak or rare response becomes strong, frequent response. Social learning Through modeling, observed behaviors become copied behaviors.

FIGURE 2.2

Three Types of Learning Behaviorism is also called “learning theory” because it emphasizes the learning process, as shown here.

Would You Talk to This Man? Children loved talking to Jean Piaget, and he learned by lis- tening carefully—especially to their incorrect explanations, which no one had paid much attention to before. All his life, Piaget was ab- sorbed with studying the way children think. He called himself a “genetic epistemologist” —one who studies how children gain knowl- edge about the world as they grow up.

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later chapters, each period fosters particular ways of thinking and acting (Inhelder & Piaget, 1958; Piaget, 1952b).

Intellectual advancement occurs because humans seek cognitive equilibrium —that is, a state of mental balance. An easy way (called assimilation) to achieve this balance is to interpret new experiences through the lens of preexisting ideas. For example, infants discover that new objects can be grasped in the same way as familiar objects, and adolescents explain the day’s headlines as evidence for their existing worldviews. For example, a news story might at first seem surprising, such

44 CHAPTER 2 ■ Theories of Development

TABLE 2.3

Piaget’s Periods of Cognitive Development

Age Range Name of Period Characteristics of the Period Major Gains During the Period Sensorimotor

Preoperational

Concrete operational

Formal operational

Infants use senses and motor abilities to understand the world. Learning is active; there is no conceptual or reflective thought.

Children think magically and poetically, using language to understand the world. Thinking is egocentric, causing children to perceive the world from their own perspective.

Children understand and apply logical operations, or principles, to interpret experiences objectively and rationally. Their thinking is limited to what they can personally see, hear, touch, and experience.

Adolescents and adults think about abstractions and hypothetical concepts and reason analytically, not just emotionally. They can be logical about things they have never experienced.

Birth to 2 years

2–6 years

6–11 years

12 years through adulthood

Infants learn that an object still exists when it is out of sight (object permanence) and begin to think through mental actions.

The imagination flourishes, and language becomes a significant means of self- expression and of influence from others.

By applying logical abilities, children learn to understand concepts of conservation, number, classification, and many other scientific ideas.

Ethics, politics, and social and moral issues become fascinating as adolescents and adults take a broader and more theoretical approach to experience.

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How to Think About Flowers A person’s stage of cognitive growth influences how he or she thinks about everything, including flowers. (a) To 7-month-old Maya, in the sen- sorimotor stage, flowers are “known” through pulling, smelling, and even biting. (b) A slightly older child might be egocentric, wanting to pull up all the flowers within reach, now. (c,d) At the adult’s formal opera- tional stage, flowers can be part of a larger, logical scheme—either to earn money or to cultivate beauty. Thinking is an active process from the beginning of life until the end.

cognitive equilibrium In cognitive theory, a state of mental balance in which people are not confused because they can use their existing thought processes to under- stand current experiences and ideas.

➤Answer to Observation Quiz (from page 41): Six hours, or one-third less time. Note that later on, the wire-fed monkeys (compared with the cloth-fed monkeys) spent equal, or even more, time on the cloth mothers.

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as the report that a suicide bomber had killed 23 people in Afghanistan on Febru- ary 27, 2007. But, as an analysis of the story noted, most people interpret news headlines using existing concepts, much as Vice President Richard Cheney did when he said that such suicide bombings are proof that terrorism is still a world- wide threat, or as critics of President Bush did when they said that the U.S. govern- ment was being distracted by the ongoing conflict in Iraq (Sanger, 2007, p. A-1).

Sometimes a new experience is jarring and incomprehensible. Then the indi- vidual experiences cognitive disequilibrium, an imbalance that initially creates con- fusion. As Figure 2.3 illustrates, disequilibrium leads to cognitive growth because people must adapt their old concepts. Piaget describes two types of adaptation:

■ Assimilation, in which new experiences are reinterpreted to fit into, or assimi- late with, old ideas

■ Accommodation, in which old ideas are restructured to include, or accommo- date, new experiences

Accommodation requires more mental energy than assimilation, but it is some- times necessary because new ideas and experiences may not fit into existing cog- nitive structures. Accommodation produces significant intellectual growth, including advancement to the next stage of cognitive development. For example, if your mother says something you never expected her to (such as “I’m going to study ballet”), you will experience cognitive disequilibrium and you will need to adapt. You might assimilate your mother’s words by deciding she didn’t mean what she said. Intellectual growth would occur if, instead, you accommodate by expanding and revising your concept of your mother.

Ideally, when people disagree, adaptation is mutual. For example, parents are often startled by their adolescents’ strong opinions—perhaps that all drugs should be legalized or that even cigarettes should be outlawed. Parents may grow intellec- tually if they revise their concepts. As the adolescents become emerging adults, they, too, might revise their notions of their parents. Cognitive growth is active, re- sponsive to clashing ideas and challenging experiences, not primarily dependent on maturation (as postulated in psychoanalytic theory) or repetition (as postulated in behaviorism).

Grand Theories 45

Equilibrium

New Idea or Experience

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Challenge Me Most of us, most of the time, prefer the comfort of our conventional con- clusions. According to Piaget, however, when new ideas disturb our thinking, we have an opportunity to expand our cognition with a broader and deeper understanding.

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sociocultural theory An emergent theory that holds that development results from the dynamic interaction between each per- son and the surrounding social and cultural forces.

46 CHAPTER 2 ■ Theories of Development

SUMMING UP

The three grand theories originated almost a century ago, each pioneered by men who developed theories so comprehensive and creative that they deserve to be called “grand.” Each theory has a different focus: emotions (psychoanalytic theory), actions (behaviorism), or thoughts (cognitive theory) (see Figure 2.4).

Freud and Erikson thought it was important to understand unconscious drives and early experiences in order to understand personality and actions. Behaviorists instead stress experiences in the recent past, especially learning by association, by reinforce- ment, and by observation. Cognitive theory holds that, to understand people, we need to appreciate how they think. According to Piaget, the way people think changes with age as their brains mature and their experiences challenge their past assumptions.

Emergent Theories You have surely noticed that the grand theorists were all men born more than a hundred years ago whose biological and academic ancestors were from western Europe and North America. These background variables are limiting. (Of course, female, non-Western, and contemporary theorists are limited by their back- grounds as well.)

Two new theories have emerged that, unlike the grand theories, are multicul- tural and multidisciplinary, developed not only by men of European ancestry but also by many non-Western, non-White, and female scientists. One, sociocultural theory, draws on research in education, anthropology, and history. The other, epige- netic theory, arises from biology, genetics, and neuroscience. The wide-ranging multicultural and multidisciplinary approach makes these theories particularly pertinent to our study.

Neither emergent theory has yet developed a comprehensive, coherent expla- nation of all of human development, of how and why people change. However, both provide significant and useful frameworks leading to better understanding, which is precisely what good theories do.

Sociocultural Theory Although “sociocultural theory is still emerging” (Rogoff, 1998, p. 687), many de- velopmentalists believe that “individual development must be understood in, and cannot be separated from, its social and cultural-historical context” (Rogoff, 2003, p. 50). The central thesis of sociocultural theory is that human development results from the dynamic interaction between developing persons and their surrounding society.

Cultural Variations Consider this question: What should you do if your 6-month-old daughter starts to fuss? You could give her a pacifier, turn on a musical mobile, change her diaper, prepare a bottle, rock her, sing a lullaby, offer a breast, shake a rattle, ask for help, or close the door and walk away. Each is the right thing to do in some cultures but not in others. In fact, some parents are warned not to “spoil” their crying babies by picking them up, while others are told that if they let their babies cry, they are abusive and neglectful.

Few adults realize that their responses are shaped by culture, yet this is pre- cisely the case, according to sociocultural theory. Societies provide not only cus- toms but also the tools and theories. For instance, some places have no pacifiers,

Behaviorism: Actions

(what the person does)

Cognitive theory: Ideas, beliefs, assumptions

Psychoanalytic theory:

Emotions (love, hate, fear, etc.)

FIGURE 2.4

Major Focuses of the Three Grand Theories

➤Answer to Observation Quiz (from page 42): The obvious part of the answer is that one girl is feeding her doll and the other is pretending to smoke a cigarette, but modeling goes far beyond that. Notice that the first girl is holding her spoon at exactly the same angle as her mother is holding hers, and that the positions of the second girl’s hand, fingers, and arm mirror her mother’s.

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bottles, or mobiles—or even diapers or doors. The tools available for baby care profoundly affect parents and infants in ways that echo throughout life. Posses- sions and privacy are valued much more in some cultures than in others, a value learned in infancy.

The pioneer of the sociocultural perspective was Lev Vygotsky (1896–1934), a psychologist from the former Soviet Union. Vygotsky studied cognitive compe- tency among the ethnically and economically diverse people of his huge nation, as well as among children who were mentally retarded. He studied how Asian farm- ers used tools, how illiterate people used abstract ideas, and how children learned in school. In his view, each person, schooled or not, is taught by more skilled members of his or her community (Vygotsky, 1934/1986).

Novices must acquire whatever knowledge and capabilities their society re- quires. This is best accomplished through guided participation: Tutors (not only those designated to teach, but also friends and strangers who know more than the novice) engage learners in joint activities, offering not only instruction but also “mutual involvement in several widespread cultural practices with great impor- tance for learning: narratives, routines, and play” (Rogoff, 2003, p. 285).

Each of us begins life knowing nothing about our culture, which includes such basic knowledge as how and what to eat, when to express emotions, and even how to communicate. Guided participation (also called apprenticeship in thinking) is a central concept of sociocultural theory. Learning is informal, social, and pervasive.

One of my students recently came to my office with her young son, who eyed my candy dish but held tightly to his mother’s hand.

“He can have one if it’s all right with you,” I whispered. She nodded and told him, “Dr. Berger will let you have one piece of candy.” He smiled shyly and quickly took one. “What do you say?” she prompted. “Thank you,” he replied, glancing at me out of the corner of his eye. “You’re welcome,” I said. In that brief moment, all three of us were engaged in guided participation. We

were surrounded by cultural traditions and practices, including my role as profes- sor, the fact that I have an office and a candy dish (a custom that I learned from one of my teachers), and the authority of the parent. This mother had taught her son to say thank you, as some families do and others don’t. Specifics differ, but all adults teach children skills they may need in their society.

Social interaction is pivotal in sociocultural theory (Wertsch & Tulviste, 2005). This contrasts with learning in the grand theories, which depends, primarily, on ei- ther the student or the teacher, not on both simultaneously. In guided participa- tion neither student nor teacher is passive; they learn from each other, through words and activities that they engage in together (Karpov & Haywood, 1998), be- cause “cognitive development occurs in, and emerges from, social situations” (Gauvain, 1998, p. 191).

The concept that cultural patterns and beliefs are social constructions (ex- plained in Chapter 1) is easy for sociocultural theorists to grasp. They believe that socially constructed ideas are no less powerful than physical or emotional con- straints; indeed, quite the opposite is true. For example, for centuries, women were not allowed to work as firefighters. Reasons centered on their physical limi- tations (they were too weak to pull hoses), and questions about their judgment (they were too emotional to deal with emergencies). But now it seems that the so- cial reasons (it just wasn’t proper) were (and are) more powerful.

Values shape development, even though values are constructed. This point was stressed by Vygotsky, who believed that mentally and physically disabled children should be educated (Vygotsky, 1925/1994). That belief has taken hold in U.S.

Especially for Nurses Using guided participation, how would you teach a young child who has asthma to breathe with a nebulizer?

Emergent Theories 47

guided participation In sociocultural theory, a technique in which skilled mentors help novices learn not only by providing instruc- tion but also by allowing direct, shared involvement in the activity. Also called apprenticeship in thinking.

The Founder of Sociocultural Theory Lev Vygotsky, now recognized as a seminal thinker whose ideas are revolutionizing education and the study of development, was a contemporary of Freud, Skinner, Pavlov, and Piaget. Vygotsky did not attain their eminence in his lifetime, partly because his work, conducted in Stalinist Russia, was largely inaccessible to the Western world and partly because he died young, at age 38.

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culture in the past 30 years, revolutionizing the education of children with special needs (Rogoff, 2003).

The Zone of Proximal Development According to sociocultural theory, people always learn in the same way, whether they are learning a manual skill, a social custom, or a language. For learning to occur, a teacher (parent, peer, or professional) must locate the learner’s zone of proximal development, which consists of the skills, knowledge, and concepts that the learner is close to acquiring but cannot yet master without help.

Through sensitive assessment of the learner, the teacher engages the student and together, in a “process of joint construction,” new knowledge is attained (Valsiner, 2006). The teacher must avoid two opposite dangers: boredom and fail- ure. Some frustration is permitted, but the learner must be actively engaged, never passive or overwhelmed (see Figure 2.5).

To make this seemingly abstract process more concrete, consider an example: a father teaching his daughter to ride a bicycle. He begins by rolling her along, sup- porting her weight while telling her to keep her hands on the handlebars, to push the right and left pedals in rhythm, and to look straight ahead. As she becomes more comfortable and confident, he begins to roll her along more quickly, praising her for steadily pumping. Within a few lessons, he is jogging beside her, holding only the handlebars. When he senses that she could maintain her balance by her- self, he urges her to pedal faster and slowly loosens his grip. Perhaps without even realizing it, she is riding on her own.

zone of proximal development In sociocul- tural theory, a metaphorical area, or “zone,” surrounding a learner that includes all the skills, knowledge, and concepts that the person is close (“proximal”) to acquiring but cannot yet master without help.

48 CHAPTER 2 ■ Theories of Development

too difficult) or able

to learn (don’t teach; What

the learner is not yet ready

(d

on ’t r

eteac h; too boring)

Th

e l earn

er

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t th e le

arner already knows

exci ting, challenging) w

ith g uidance (do teach; Wh

at th e lear

ner could understand Zo ne

of P roximal Development

FIGURE 2.5

The Magic Middle Somewhere between the boring and the impossible is the zone of proximal development, where interaction be- tween teacher and learner results in knowl- edge never before grasped or skills not already mastered. The intellectual excitement of that zone is the origin of the joy that both instruction and study can bring

Especially for Teachers Following Vygotsky’s precepts, how might you teach reading to an entire class of first-graders at various skill levels?

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Note that this is not instruction by preset rules. Sociocultural learning is active: No child learns to ride a bike by reading and memorizing written instructions, and no good teacher merely repeats a prepared lesson.

Because each student has personal traits, experiences, and aspirations, educa- tion must be individualized. Learning styles vary: Some children need more assur- ance than others; some learn best by looking, others by hearing. A mentor needs to sense when support or freedom is needed and how peers can help (they are some- times the best mentors). Teachers know how the zone of proximal development expands and shifts.

Excursions into and through the zone of proximal development, such as the boy prompted to say “thank you” or the girl learning to balance on a bike, are common- place for all of us. Our mentors, attuned to ever-shifting abilities and motivation, continually urge a new level of competence; learners ask questions, show interest, and demonstrate progress, thus guiding and inspiring the mentors. When edu- cation goes well, both teachers and students are fully engaged and productive. Particular skills and processes vary enormously from culture to culture, but the overall social interaction is the same.

Sociocultural theorists have been criticized for overlooking developmental processes that are not primarily social. Vygotsky’s theory, in particular, may neglect the power of genes to guide development, especially if neurological immaturity or disability makes some learning impossible (Wertsch, 1998). Every child can learn, but not every child can learn anything at any moment. Further, while culture is pervasive and informal teachers abound, the prevailing sociocultural values are not necessarily always best.

Epigenetic Theory The central idea of epigenetic theory is that genes interact with the environ- ment to allow development (Gottlieb, 2003). Epigenetic development contrasts sharply with preformism, the theory that genes determine every aspect of develop- ment.

Epigenetic theory is the newest developmental theory, but it incorporates several established bodies of research. Many disciplines—including biology (especially the principles of evolution), genetics, and chemistry—provided a foundation. Many psychologists, including Erikson and Piaget, described aspects of their theories as epigenetic, recognizing that development builds on genes but is not determined by them.

Many specialties within the social sciences—especially sociobiology (the study of how individuals within society seek to pass along their genetic heritage), evolu- tionary psychology (the study of the inherited patterns of behavior that were once adaptive), and ethology (the study of animals in their natural environments)— stress the interaction of genes and the environment.

With, On, and Around the Genes What, then, is new about epigenetic theory? One way to answer that question is to consider the name, derived from the root word genetic and the prefix epi-. Genetic refers to the entire genome, which includes (1) the particular genes that make each person (except monozygotic twins) genetically unique, (2) the genes that dis- tinguish our species as human, and (3) the genes that all living creatures share.

We now know that all psychological as well as all physical traits—from bashful- ness to blood type, from moodiness to metabolism, from vocational aptitude to voice tone—are influenced by genes. How religious a person is, or whether some- one votes for a liberal candidate, is influenced by genes (Bouchard et al., 2004).

epigenetic theory An emergent theory of development that considers both the genetic origins of behavior (within each person and within each species) and the direct, systematic influence that environ- mental forces have, over time, on genes.

Emergent Theories 49

Learning to Ride Although they are usually not aware of it, children learn most of their skills because adults guide them carefully. What would happen if this father let go?

AR IE

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➤Response for Nurses (from page 47): You would guide the child in the zone of proximal development, where teacher and child interact. Thus, you might encourage the child to prepare the nebulizer (by putting in the medicine, for instance) and then breathe through it yourself, taking turns with the child.

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Even the timing of developmental change is genetic: Humans walk and talk at about 1 year and can have babies in adolescence because genes switch on those abilities (unless something is terribly wrong). Thus, half of epigenetic theory is about the power of genes.

The other half is equally important. The prefix epi- means “with,” “around,” “be- fore,” “after,” “on,” or “near.” Thus, epigenetic refers to all the surrounding factors that affect the expression of genetic influences. Those factors stop some genes before they have any effect, and they give other genes extensive influence. Some factors cause stress, such as injury, temperature, and crowding; some facilitate, such as nourishing food, loving care, and freedom to play. In “epigenetic program- ming . . . environmental effects on . . . health or behavior are mediated through al- tered gene expression” as well as vice versa (Moffitt et al., 2006, pp. 5–6).

Epigenetic theory puts the two halves together in one word to signify this inevitable interaction between genes and the environment. This is illustrated by Figure 2.6, which was first published in 1992 by Gilbert Gottlieb, a leading pro- ponent of epigenetic theory. That simple diagram, with arrows going up and down over time, has been redrawn and reprinted dozens of times to emphasize that dynamic interaction continues in each person’s life long after conception (Gottlieb, 1992).

Epigenetic effects are easier to notice in lower animals than in people (Koolhaas et al., 2006). For example, the color of an animal’s fur is genetically de- termined, but environment causes some rabbit species to have white fur in cold climates and brown fur in warm ones.

Even biological sex can be epigenetic. Alligator eggs become males when the nest temperature is 34ºC or above during days 7 to 21 of incubation and hatch as females at nest temperatures of 28–31ºC (Ferguson & Joanen, 1982). For humans, the age of the parents correlates with the sex of their child, an epigenetic effect. Teenagers conceive more boys.

As development progresses, each person proceeds along the course set by ear- lier genetic–environmental interactions, which allow a range of possible outcomes called the reaction range. Thus, some toddlers cannot be musical masters, because that is above the range of their inherited potential. But they still have a spread of possible reactions to music, depending on their experiences, from being an avid listener to being indifferent to music.

Some aspects of development become less plastic, or changeable, with age (Baltes et al., 2006), which explains why prenatal conditions (e.g., drugs or alcohol) damage the brain and body of a fetus far more than they damage the pregnant woman. However, even in adulthood contexts can change inherited patterns.

50 CHAPTER 2 ■ Theories of Development

Environment (physical, cultural, social)

Behavior

Neural activity

Individual development

Genetic activity

Conception Death

Bidirectional influences

Source: Adapted from Gottlieb, 1992.

FIGURE 2.6

An Epigenetic Model of Development Notice that there are as many arrows going down as going up, at all levels. Although de- velopment begins with genes at conception, it requires that all four factors interact.

Observation Quiz (see answer, page 52): According to this diagram, does genetic influence stop at birth?

➤Response for Teachers (from page 48): First of all, you wouldn’t teach them “to read”; you would find out each child’s skill level and what he or she was capable of learning next, so that instruction would be tailored to each child’s zone of proximal development. For some, this might be letter recognition; for others, comprehension of paragraphs they read silently. Second, you wouldn’t teach the whole class. You would figure out a way to individualize instruction—maybe by forming pairs, with one child teaching the other; by setting up appropriate computer instruction; or by having parents or other teachers (maybe older children) work with small groups of three or four children.

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Dramatic evidence comes from drug addiction. A person’s potential to become addicted is genetic. That potential can be realized—a genetically vulnerable per- son becomes an addict or alcoholic—if the person repeatedly consumes an addic- tive substance. Thus, addiction is epigenetic, the outcome of the interaction of genes and environment. Even monozygotic twins (who have the same genes) can differ in whether or not they become alcoholics (Moffitt et al., 2006).

Once people are addicts, something in their biochemistry and brain makes them hypersensitive to that drug. For example, one drink makes a nonalcoholic pleasantly tipsy but awakens a powerful craving in the alcoholic. The role of expe- rience in addiction and in creating hypersensitivity to a drug has been demon- strated in countless experiments (Crombag & Robinson, 2004). Nonetheless, as one team of researchers explains:

Within the epigenetic model, each intermediary phenotype [genetic manifesta- tion] is an outcome as well as a precursor to a subsequent outcome contingent on the quality of person–environment interactions. . . . Sudden shifts . . . can occur. . . . [For example,] 86 percent of regular heroin users among soldiers in Vietnam abruptly terminated consumption upon return to the United States (Robins, Helzer, & Davis, 1975). In effect, a substantial change in the environ- ment produced a major phenotype change.

[Tarter et al., 1999, p. 672]

The fact that these addicted soldiers kicked the habit permanently is astonish- ing to anyone who has watched an addict get “clean” and then relapse time after time. The conventional explanation for the repeated relapses is that, once a person is addicted, the biochemical pull of the drug is too strong to resist. However, the example of the Vietnam veterans suggests that the biochemical (and genetic) as- pect of addiction does not work in isolation; the social context (epi-) is powerful as well—a point confirmed by more recent research (Baker et al., 2006).

Thus, a crucial aspect of epigenetic theory is that genes never function alone; their potential is not actualized unless certain epi- factors occur. For example, many psychological disorders, including schizophrenia, autism, antisocial person- ality disorder, and some forms of depression, have a genetic component. But none are purely genetic; all are epigenetic, with the severity and even the existence of the psychopathology dependent on environment as well as genes (Krueger & Markon, 2006; Moffitt et al., 2006).

People who inherit a particular variant of one gene (called the short allele of 5-HTT) are more likely to become depressed. However, even people who have this variant do not usually become depressed unless they are maltreated as children or experience stressful events as adults (Caspi et al., 2003). Epigenetic again.

Genetic Adaptation So far we have described epigenetic factors that affect individuals. Epigenetic fac- tors also affect groups of people and entire species. It is apparent that over billions of years there has been “continual reorganization of epigenetic and genetic deter- minants.” That makes it foolhardy to try to understand species development, even of lower organisms, as solely genetic, transmitted without change over eons (New- man & Müller, 2006, p. 61). Selective adaptation of genes and environments is ongoing, which means that the environment favors genes in a population if they increase survival and reproduction. At the same time, selective adaptation makes destructive genes increasingly rare.

Selective adaptation begins when a particular genetic variant benefits the or- ganism that has it, enabling survival and many offspring. About half of those off- spring inherit the same gene as their fortunate father or mother. They, too, will

selective adaptation The process by which humans and other organisms gradually adjust to their environment. Specifically, the frequency of a particular genetic trait in a population increases or decreases over generations, depending on whether or not the trait contributes to the survival and reproductive ability of members of that population.

Emergent Theories 51

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have many children, and thus that beneficial gene will become more common with each succeeding generation. Eventually, almost everyone has that gene and the entire population thrives.

Whether a gene is beneficial, harmful, or neutral depends on the particular en- vironment. For instance, allergy to bee stings is genetic, but inheriting it is no problem if the neighborhood has no bees and the person does not travel. Complex genetic traits depend on the context for their impact. For example, people who in- herit fearfulness have an advantage in a hostile place (they may escape attack) but not in a benign environment (they may avoid other people). Similarly, specialized bills (for birds) or teeth (for mammals), which enable creatures to obtain food more easily, perhaps emerged first as a mutation that subsequently spread through the population. Thus, a woodpecker’s strong, narrow bill pries insects out of the bark of trees, but a duck’s broad, rounded bill strains food from water. So because of genes, a “duck out of water” is a dead duck.

Human differences can also be traced to selective adaptation. All humans may originally have been lactose-intolerant, getting sick if they drank cow’s milk; but in regions where dairy farming was introduced thousands of years ago, a few fortunate people had an odd gene that produced an enzyme that let them digest milk. They became healthier than the others, so they had more children. In fact, the genetic variant that allows milk digestion appeared in- dependently in several cattle-herding populations and spread among those people (Gibbons, 2006).

For tribes and clans as well as individuals, the interaction of genes and environment affects survival. Genetic variations are needed when conditions change. If no member of a species inher- its some variants of genes needed for adaptation, the entire species can disappear. About 90 percent of all species that ever existed

have become extinct, partly because none of the animals could adapt to changes in conditions (Buss et al., 1998). Thus far, humans have adapted well, surviving in dramatically diverse climates and ecosystems.

Epigenetic theory suggests that adaptation occurs for all living creatures, no matter where and how they live (Fish, 2002). Consider humans and chimpanzees: Those two species share 99 percent of their genes, yet there are about a million times as many humans alive at this moment than chimpanzees. That 1 percent ge- netic difference includes several characteristics that have enabled humans to sur- vive and multiply. For instance, as a species, humans are taller than chimpanzees and have longer legs, making it easier for humans to walk long distances. Bipedal (two-legged) locomotion increased mobility, enabling humans (but not chimps) to journey from Africa to distant fertile regions. Humans are the only mammals that have traveled, reproduced, and thrived on every landmass of the world (except Antarctica).

Some aspects of epigenetic theory are widely accepted, including one that helps us understand why human children and parents love each other: It origi- nates with the genes (Hofer, 2006). Children depend for survival on a decade or more of adult care, so for the human species to survive, children and parents must become attached to each other. Consequently, babies instinctively smile at faces, and a newborn’s physical appearance and trusting grasp stir almost any adult’s protective affection.

Over the millennia, unloved children were likely to die and thus never have children of their own, so parent–child affection became adaptive and widespread among the population. Parental love is strengthened by the same hormones that accompany birth—an example of selective adaptation that I know well.

52 CHAPTER 2 ■ Theories of Development ST

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Got Milk! Many people in Sweden (like this pair) and the other Scandinavian countries regularly drink cow's milk and digest it easily. That may be because their ancient occupation of cattle herding coincided with a genetic tendency toward lactose tolerance.

Especially for Students Who are Bored with Reading About Genes How can reading this textbook help you live longer and be happier?

➤Answer to Observation Quiz (from page 50): No. Arrows originating with genetic activity extend throughout development until death.

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Emergent Theories 53

My Beautiful, Hairless Babies

In the beginning, infants accept help from anyone—a good sur- vival strategy during the centuries when women regularly died in childbirth. By the time they are able to crawl, however, in- fants are emotionally attached to their specific caregivers and fearful of unfamiliar situations—another good survival tactic.

Both accepting help and forming attachments are evidence of selective adaptation. Infants who stayed near caregivers were unlikely to be lost in a blizzard or eaten by an animal in the jun- gle—and thus survived to have children of their own. Stressed adults, especially women, are hormonally inclined to “tend and befriend,” another survival impulse (Taylor, 2006).

Adults are genetically disposed to nurture babies. Logically, no reasonable person would become a parent. It is irrational to endure sleepless nights, dirty diapers, and years of self-sacrifice. But reason and logic disappear when it comes to mothering, which can be a “minefield” for destructive emotions and actions in mothers, fathers, and children (Hrdy, 2000). Yet millions of adults undergo substantial pain and expense in their quest for the joy of parenthood.

As the mother of four, I have been surprised by the power of genetic programming many times. With my first-born, I asked my pediatrician whether Bethany wasn’t one of the most beauti- ful, perfect babies he had ever seen.

“Yes,” he said, with a twinkle in his eyes, “and my patients are better looking than the patients of any other pediatrician in the city.”

When my second child was 1 day old, the hospital offered to sell me a photograph of her—hairless, chinless, and with swollen eyelids. I glanced at it and said no, because the photo didn’t look at all like her—it made my beautiful Rachel look al- most ugly. I was similarly enamored of Elissa and Sarah.

However, I am not only a woman who loves her children; I am also a woman who loves her sleep. On one predawn morning, as I roused myself yet again to feed Sarah, I asked myself why I had chosen for the fourth time to add someone to my life who I knew would deprive me of my precious slumber. The answer, of course, is that some genetic instincts are even stronger than the instinct for comfort.

in person

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Open Wide Caregivers and babies elicit responses from each other that ensure survival of the next generation. The caregiver’s role in this vital interaction is obvious, but infants do their part. They chirp, meow, whine, bleat, squeal, cry, or otherwise signal hunger—and then open their mouths wide when food arrives. Both the baby birds and the baby human obviously know what to do.

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SUMMING UP

The two emergent theories point in opposite directions. Sociocultural theory looks out- ward, to the overarching social, historical, and cultural patterns that affect communities, families, and, ultimately, individuals. Sociocultural theory emphasizes that social and cultural groups transmit their values and skills to children through the zone of proximal development, which differs for each learner. By contrast, epigenetic theory begins by looking inward, at thousands of genes, and then moves outward to incorporate the envi- ronmental factors that directly affect the expression of those genes. Epigenetic theory includes individual genetic transmission and centuries-old, species-wide adaptation. Both of these emergent theories combine insights, data, and methods from many academic disciplines and take into account current research and techniques.

■

What Theories Contribute Each major theory discussed in this chapter has contributed a great deal to our understanding of human development (see Table 2.4):

■ Psychoanalytic theory has made us aware of the impact of early-childhood experiences, remembered or not, on subsequent development.

■ Behaviorism has shown the effect that immediate responses, associations, and examples have on learning.

■ Cognitive theory reveals how thoughts, beliefs, and intellectual frameworks affect every aspect of our development.

■ Sociocultural theory reminds us that human development is embedded in a rich and multifaceted cultural context, evident in every social interaction.

■ Epigenetic theory emphasizes the interaction between genetic instructions and surrounding contexts.

In order, these five theories focus on: early childhood, environment, mind, culture, and genes. No comprehensive view of development can ignore any of these factors.

Each theory has faced severe criticism. Psychoanalytic theory has been faulted for being too subjective; behaviorism, for being too mechanistic; cognitive theory, for undervaluing cultural diversity; sociocultural theory, for neglecting individual initiative; and epigenetic theory, for neglecting the human spirit. Depending on one’s perspective, all the major theories can be considered as variations on the universal human experience (McAdams & Pals, 2006). Alternatively, each can be seen as “fundamentally irreconcilable” (Wood & Joseph, 2007, p. 57).

54 CHAPTER 2 ■ Theories of Development

TABLE 2.4

Five Perspectives on Human Development

Fundamental Depiction of Relative Emphasis on Theory Area of Focus What People Do Nature or Nurture?

Psychosexual (Freud) or psychosocial (Erikson) stages

Conditioning through stimulus and response

Thinking, remembering, analyzing

Social context, expressed through people, language, customs

Genes and factors that repress or encourage genetic expression

Battle unconscious impulses and overcome major crises

Respond to stimuli, reinforcement, and models

Seek to understand experiences while forming concepts and cognitive strategies

Learn the tools, skills, and values of society through apprenticeships

Develop impulses, interests, and patterns inherited from ancestors

Psychoanalytic theory

Behaviorism

Cognitive theory

Sociocultural theory

Epigenetic theory

More nature (biological, sexual impulses, and parent–child bonds)

More nurture (direct environment produces various behaviors)

More nature (person’s own mental activity and motivation are key)

More nurture (interaction of mentor and learner, within cultural context)

Begins with nature; nurture is also crucial, via nutrients, toxins, and so on

➤Response for Students Who are Bored With Reading About Genes (from page 52): Genetic adaptation of the species has allowed people to learn from one another, thus preventing extinction of the human race. The same process might apply to individuals learning in college.

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Most developmentalists prefer an eclectic perspective. That is, rather than adopt any one of these theories exclusively, they make selective use of all of them, sometimes severely criticizing or ignoring one or another, but always open to sur- prises from scientific studies that cause rethinking and new theorizing. Research in human development has been characterized as “theoretical pluralism,” because no single theory fully explains the behavior of humans through the life span (Dixon & Lerner, 1999).

Being eclectic, not tied to any one theory, is beneficial because everyone, scien- tists as well as laypeople, tends to be biased. It is easy to dismiss alternative points of view, but using all five theories opens our eyes and minds to aspects of develop- ment that we might otherwise ignore. Remember the father at the start of this chapter whose 5-year-old said “I hate you”? If the father’s first response is a slap, he might recognize that each of these five theories would suggest he reconsider that harsh reaction.

Whatever the limitations of particular theories, developmental theories time and time again illuminate life’s myriad experiences and events. Development is dazzling and confusing without some perspective. Ideology and prejudice easily overcome reality without scientific theory and data. One illustration comes from the dispute that has echoed through every decade of developmental study: the nature–nurture controversy.

The Nature–Nurture Controversy Nature refers to the genes that people inherit. Nurture refers to all the environ- mental influences, beginning with the mother’s health and diet during prenatal development and continuing lifelong, including the individual’s experiences with family, school, community, society.

Nature and Nurture Always Interact The nature–nurture controversy has many other names, among them heredity ver- sus environment and maturation versus learning. Under whatever name, the basic question is: How much of any characteristic, behavior, or pattern of development is the result of genes and how much is the result of experiences?

Family responses make a child’s genetic tendencies develop. Nature and nurture interact (Moffitt et al., 2006; Reiss et al., 2000). The family responses are elicited by the child’s genes, but each parent’s genes, status (as biological, adoptive, or stepparent), culture, experience, and so on affect how he or she acts. The combi- nation of child and parent, nature and nurture—not one or the other alone— leads to development.

This interaction is complex—“feedback loops swirling in all directions, all inex- tricably intertwined” (Lippa, 2002, p. 197)—yet developmentalists seek to under- stand how nature and nurture interact for each trait. As one expert wrote:

Both nature and nurture now have seats at the theoretical table, and so the really hard work now begins—to specify, in nitty gritty detail, exactly how the many biolog- ical and social environmental factors identified by recent theories weave together.

[Lippa, 2002, p. 206]

Theories help with this “really hard work.” Imagine a parent and a teacher dis- cussing a child’s behavior. Each suggests a possible explanation that makes the other say, “I never thought of that.” Having five theories is like having five very perceptive observers. All five are not always on target, but it is certainly better to use alternate theories to expand perception than to stay stuck in one narrow groove. A hand functions best with five fingers, even though some fingers are more useful than others. To get back to nature and nurture, the five theories differ in how and when

eclectic perspective The approach taken by most developmentalists, in which they apply aspects of each of the various theo- ries of development rather than adhering exclusively to one theory.

What Theories Contribute 55

nature A general term for the traits, capaci- ties, and limitations that each individual inherits genetically from his or her parents at the moment of conception.

nurture A general term for all the environ- mental influences that affect development after an individual is conceived.

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they see the interaction between the two, and since no simple formula describes the nature–nurture combination, it is helpful to consider many perspectives.

Theoretical Perspectives on Hyperactivity and Homosexuality Consider two very different human characteristics: hyperactivity and homosexual- ity. How, and to what extent, are nature and nurture involved in each?

Some children seem always active, running around or restless even when they should be still. They are impulsive, unable to attend to anything for more than a moment. These are symptoms of attention-deficit/hyperactivity disorder, or ADHD (American Psychiatric Association, 2000). The symptoms and treatment are dis- cussed in Chapter 11, but here let us look at how nature and nurture contribute.

Several facts support the idea that this disorder is genetic. Children with ADHD share the following characteristics:

■ They are usually boys who have male relatives with the same problem. ■ They are overactive in every context, home as well as school. ■ They are often calmed by stimulants, such as Ritalin, Adderall, and even coffee.

This last fact convinces many: Since biochemical treatment works, the cause of ADHD must be biochemical—that is, essentially, “nature” (Faraone et al., 2005). Many researchers are looking for better drugs, believing that nature is the cause (e.g., Lopez, 2006).

But wait. There is also evidence that “nurture,” or something in the environ- ment, is the cause:

■ The rapid increase in ADHD (from 1 to 5 percent of all U.S. children within the past 50 years) cannot be genetic, since selective adaptation takes centuries.

■ Many environmental factors correlate with ADHD, including crowded homes, television, lead, food additives, and rigid teaching (e.g., Bateman et al., 2004).

Now consider the influence of nature and nurture on homosexuality. Most social scientists once theorized that homosexuality was the product of nurture. Psycho- analytic theory blamed a weak father and an overbearing mother; behaviorists thought that people learned sexual behavior; cognitive theory suggested that some people’s thoughts about family and society led them to rebel by becoming homo- sexual; sociocultural theorists noted that the frequency of homosexuality in a soci- ety depended on whether everyone was expected to be homosexual during adolescence or whether homosexuals were killed, or something in between. Thus nurture, whether within the individual, the family, or the culture, was seen as causing homosexuality.

However, when scientists tried to confirm these theories, they found that chil- dren raised by homosexual couples (either adopted or the biological offspring of one of the parents) become heterosexual or homosexual in about the same propor- tions as children raised by heterosexuals and do not seem particularly rebellious or emotionally disturbed (Patterson, 2006; Wainwright et al., 2004). Researchers fol- lowing the sociocultural perspective began to make a distinction between sexual orientation (erotic inclinations and thoughts) and sexual expression (actual be- havior); those researchers found that many people have homosexual impulses (na- ture), which they do not express in hostile cultures but do express in more receptive cultures. Thus nurture affects only expression, not orientation. In fact, depending on definition and context, between 1 percent (self-proclaimed identity of lesbians in the United States) and 21 percent (sexual attraction to other girls among female adolescents in Norway) of people are homosexual (Savin-Williams, 2006). How much of homosexuality is nature and how much is nurture depends partly on definition.

56 CHAPTER 2 ■ Theories of Development

sexual orientation A person’s impulses and internal direction regarding sexual interest. A person may be oriented to people of the same sex, of the other sex, or of both sexes. Sexual orientation may differ from sexual expression, appearance, identity, or lifestyle.

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No Answers Yet Both hyperactivity and homosexuality are discussed in greater detail later in this text. This chapter is not the place to decide how much nature or nurture con- tributes to either of them. Epigenetic theory emphasizes that interaction is key. Choosing nature or nurture is “a dangerous quagmire.” According to some psy- chologists:

Those who dichotomize sexual orientation into pure biological or social causation fall into a dangerous quagmire. To deny any role for biology affirms an untenable scientific view of human development. Equally harsh and deterministic would be to deny the significance of the environment.

[Savin-Williams & Diamond, 1997, p. 235]

Similar complications are evident for ADHD. If one monozygotic twin is hyperactive, the other twin is also likely to be (evidence for nature) but is not always (evi- dence for nurture) (Lehn et al., 2007).

The problem for both homosexuality and hyperactivity is that opinions about them may be harmful. For exam- ple, those who emphasize nurture worry that boisterous children are needlessly medicated for ADHD (Breggin, 2001). Many believe that, by not accepting homosexual- ity as part of nature, societies impair the mental health of people by making them feel ashamed about being who they are (Omoto & Kurtzman, 2006).

Impassioned but opposite opinions about nature and nurture that can lead to developmental harm are evident regarding many other issues in development, including birth defects, school curricula, aggression, marriage, di- vorce, and retirement. Ideology and ignorance often add to polarization. As one scholar, using the example of ag- gression, points out: “Individual differences in aggression can be accounted for by genetic or socialization differ- ences, with politically conservative scientists tending to believe the former and more liberal scientists the latter” (M. Lewis, 1997, p. 102). Many questions for developmental scientists become weapons in cultural or political wars.

On nature versus nurture, “opinions shift back and forth between extreme posi- tions” (W. Singer, 2003, p. 438). Because false assumptions lead to contradictory and even harmful policies, it is critical to use scientific inquiry and data as a buffer between opinions and conclusions. How can we avoid extremes, resist the pull of ideology, and overcome bias? Consider theory! Actually, consider more than one theory, and use theory to suggest possibilities and perspectives, which will lead to hypotheses to be explored.

SUMMING UP

As the nature–nurture controversy makes clear, theories are needed to suggest hy- potheses, investigation, and, finally, answers, so that objective research can replace per- sonal assumptions. For instance, although it is now known that the parental relationship is not the cause of homosexuality, this conclusion could not be drawn until researchers tested that psychoanalytic hypothesis. Theories are not true or false, but they serve to move the scientific process forward from the first step (ask a question) to the last (draw conclusions). Given the impact of some applications (e.g., the widespread medication of children with ADHD), such progress is sorely needed.

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What Theories Contribute 57

Learning from Dad What is this boy learning from his two fathers? Tennis.

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58 CHAPTER 2 ■ Theories of Development

What Theories Do 1. A theory provides a framework of general principles to guide research and to explain observations. Each of the five major developmental theories—psychoanalytic, behaviorist, cognitive, sociocultural, and epigenetic—interprets human development from a distinct perspective, and each provides guidance for under- standing how human experiences and behaviors change over time. Good theories are practical: They aid inquiry, interpretation, and daily life.

Grand Theories 2. Psychoanalytic theory emphasizes that human actions and thoughts originate from unconscious impulses and childhood conflicts. Freud theorized that sexual urges arise during three stages of childhood development: oral, anal, and phallic. Parents’ reactions to conflicts associated with their children’s erotic im- pulses have a lasting impact on personality, according to Freud.

3. Erikson’s version of psychoanalytic theory emphasizes psycho- social development, specifically as societies, cultures, and parents respond to children. Erikson described eight successive stages of psychosocial development, each involving a developmental crisis that occurs as people mature within their context.

4. Behaviorists, or learning theorists, believe that scientists should study observable and measurable behavior. Behaviorism emphasizes conditioning—a learning process. The process of conditioning occurs lifelong, as reinforcement and punishment affect behavior.

5. Social learning theory recognizes that much of human behav- ior is learned by observing the behavior of others. The basic process is modeling. Children are particularly susceptible to so- cial learning, but all of us learn to be more or less effective be- cause of social influences.

6. Cognitive theorists believe that thought processes are power- ful influences on human attitudes, behavior, and development. Piaget proposed that children’s thinking develops through four age-related periods, propelled by an active search for cognitive equilibrium.

Emergent Theories 7. Sociocultural theory explains human development in terms of the guidance, support, and structure provided by cultures and so- cieties. For Vygotsky, learning occurs through social interactions, when knowledgeable members of the society guide learners through their zone of proximal development.

8. Epigenetic theory begins with genes, powerful and om- nipresent, affecting every aspect of development. Genes are al- ways affected by environmental influences, from prenatal toxins and nutrients to long-term stresses and nurturing families and friends. This interaction can halt, modify, or strengthen the ef- fects of the genes within the person and, via selective adaptation over time, within the species.

What Theories Contribute 9. Psychoanalytic, behavioral, cognitive, sociocultural, and epige- netic theories have each aided our understanding of human de- velopment, yet no one theory is broad enough to describe the full complexity and diversity of human experience. Most developmen- talists are eclectic, drawing upon many theories.

10. Each theory can shed some light on almost every develop- mental issue. One example is the nature–nurture controversy. All researchers agree that both genes and the environment influence all aspects of development, but the specific applications that stem from an emphasis on either nature or nurture can affect people in opposite ways. More research is needed, and theories point toward questions that need to be answered.

developmental theory (p. 33) grand theories (p. 34) emergent theories (p. 34) psychoanalytic theory (p. 35) behaviorism (p. 38) conditioning (p. 39)

classical conditioning (p. 39) operant conditioning (p. 39) reinforcement (p. 39) social learning theory (p. 42) modeling (p. 43) self-efficacy (p. 43)

cognitive theory (p. 43) cognitive equilibrium (p. 44) sociocultural theory (p. 46) guided participation (p. 47) zone of proximal development

(p. 48)

epigenetic theory (p. 49) selective adaptation (p. 51) eclectic perspective (p. 55) nature (p. 55) nurture (p. 55) sexual orientation (p. 56)

SUMMARY

KEY TERMS

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7. What would a teacher influenced by Vygotsky do?

8. How might sociocultural theory explain how students behave in class?

9. How might epigenetic theory explain the behavior of a pet dog or cat?

10. How might genetic diversity help a species survive?

11. Why are most developmentalists said to be eclectic?

12. Why does it make a difference whether hyperactivity stems primarily from nature or primarily from nurture?

1. Why do developmental scientists use theories?

2. How might a psychoanalytic theorist interpret a childhood ex- perience, such as the arrival of a new sibling?

3. How can behaviorism be seen as a reaction to psychoanalytic theory?

4. According to behaviorism, why might some teenagers begin smoking cigarettes?

5. According to Piaget’s theory, what happens when a person ex- periences cognitive disequilibrium?

6. What are the background similarities among Freud, Pavlov, and Piaget?

noting the reinforcers for each instance. Then, and only then, try to develop a substitute behavior by reinforcing yourself for it. Keep careful records; chart the data over several days. What did you learn?

3. The nature–nurture debate can apply to many issues. Ask three people to tell you their theories about what factors create a criminal and how criminals should be punished or rehabilitated. Identify which theory described in this chapter is closest to each explanation you are given.

1. Developmentalists sometimes talk about “folk theories,” which are theories developed by ordinary people, who may not know that they are theorizing. Choose three sayings commonly used in your culture, such as (from the dominant U.S. culture) “A penny saved is a penny earned” or “As the twig is bent, so grows the tree.” Explain the underlying assumptions, or theory, that each saying reflects.

2. Behaviorism has been used to change personal habits. Think of a habit you’d like to change (e.g., stop smoking, exercise more, watch less TV). Count the frequency of that behavior for a week,

KEY QUESTIONS

APPLICATIONS

Summary 59

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Heredity and Environment

enes play a leading role in the drama of human development, yet they rarely take center stage. Genes are pervasive and powerful, but they are also hidden and elusive.

One day when I arrived to pick up my daughter Rachel from school, another mother pulled me aside. She whispered that Rachel had fallen on her hand and that her little finger might be broken. My daughter was happily playing, but when I examined her finger, I saw that it was crooked. Trying to avoid both needless panic and medical neglect, I took Rachel home and consulted my husband. He smiled and spread out his hands, revealing the same bent little finger. Aha! An inherited abnormality, not an injury. But why had I never noticed this before?

That bent finger is one small example of millions of genetic surprises in human development. This chapter anticipates and explains some of those mysteries, going behind the scenes to reveal not only what genes are but also how they work. Many ethical issues are raised by genetics, and we will ex- plore those, too. First, the basics.

The Genetic Code A person is much more than a set of genetic instructions. Although life be- gins with genes, development is dynamic, ongoing, and interactional. Each person is unlike any other, not only because of unique instructions, locked in DNA, but also because of all the personal, social, and cultural influences that affect each person lifelong.

What Genes Are To reveal the secrets of the genetic code, we begin by reviewing some biology. All living things are made up of tiny cells. The work of these cells is done by proteins. Each cell manufactures certain proteins according to instructions stored at the heart of each cell in molecules of DNA (deoxyribonucleic acid). Each molecule of DNA is called a chromosome, and these chromo- somes contain the instructions to make all the proteins that a living being needs (see Figure 3.1).

Humans have 23 pairs of chromosomes (46 in all). One member of each pair is inherited from each parent. The instructions in these 46 chromo- somes are organized into units called genes, with each gene (about 25,000

3

61

CHAPTER OUTLINE

� The Genetic Code

What Genes Are The Beginnings of Life ISSUES AND APPLICATIONS:

Too Many Boys?

� From One Cell to Many

New Cells, New Functions Gene–Gene Interactions More Complications IN PERSON: “I Am Not Happy With Me”

� From Genotype to Phenotype

Addiction Visual Acuity Practical Applications

� Chromosomal and Genetic Abnormalities

Not Exactly 46 Chromosomes Dominant-Gene Disorders Fragile X Syndrome Recessive-Gene Disorders Genetic Counseling and Testing THINKING LIKE A SCIENTIST:

Who Decides?

G

DNA (deoxyribonucleic acid) The molecule that contains the chemical instructions for cells to manufacture various proteins.

chromosome One of the 46 molecules of DNA (in 23 pairs) that each cell of the human body contains and that, together, contain all the genes. Other species have more or fewer chromosomes.

gene A section of a chromosome and the basic unit for the transmission of heredity, consisting of a string of chemicals that code for the manufacture of certain proteins.

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in all for a human) located on a particular chromosome. Thus, every gene is a sep- arate section of a chromosome, and each gene contains the instructions for mak- ing a specific type of protein.

You are familiar with proteins in the diet. But what exactly is a protein? A pro- tein is composed of a sequence of chemicals, a long string of building blocks called amino acids. The recipe that a cell needs to manufacture a protein consists of instructions for stringing together the right amino acids in the right order. These instructions are transmitted to the cell via pairs of only four chemicals called bases (adenine, thiamine, cytosine, and guanine, abbreviated A, T, C, and G), which pair up in only four possible ways (A-T, T-A, C-G, and G-C). There are more than 3 billion pairs in all, and these are arranged in triplets (three pairs) on those 25,000 genes.

Most genes have thousands of precise pairs and triplets, making amino acids (20 types in all). Some instructions are crucial, and any alterations in their code— even a few extra repeats of a triplet—can be fatal. Other unusual codes are normal variations, and still others make no difference that scientists can see (Marcus, 2004).

The entire packet of instructions to make a living organism is called the genome. There is a genome for every species of plant and animal. Each person (except monozygotic twins) has a slightly different code, but the human genome is 99.9 percent the same for any two persons. Our similarities far outweigh our differences.

genome The full set of genes that are the instructions to make an individual member of a certain species.

62 CHAPTER 3 ■ Heredity and Environment

Nucleus 23 pairs of chromosomes

Amino acid

Strands of double helix

Triplet (specifies an amino acid)

Triplet (specifies an amino acid)

Amino acid

PROTEIN

CELL

GENE

NUCLEUS CHROMOSOME (DNA MOLECULE = DOUBLE HELIX)

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Gene

FIGURE 3.1

How Proteins Are Made The genes on the chromosomes in the nucleus of each cell instruct the cell to manufacture the proteins needed to sustain life and development.

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The human genome contains about 25,000 genes (on 46 chromosomes), which instruct the developing body to produce the proteins that make each person unique, yet similar to all other humans. The total is awe-inspiring. As one expert explains:

If each triplet is considered a word, this sequence of genes is . . . as long as 800 Bibles. If I read the genome out to you at the rate of one word per second for eight hours a day, it would take me a century. . . . This is a gigantic document, an immense book, a recipe of extravagant length, and it all fits inside the micro- scopic nucleus of a tiny cell that fits easily upon the head of a pin.

[Ridley, 1999, p. 7]

There is another amazing part of human genetics: how genes work together to make human beings.

The Beginnings of Life Development begins at conception, when a male reproductive cell (sperm; plural: sperm), penetrates the membrane of a female reproductive cell (ovum; plural: ova). Each human reproductive cell, or gamete, contains 23 chromosomes, half of that person’s 46. Thus, although each man has two chromosomes at each site (two at the 10th site, for instance), each of his sperm has only one chromosome at the 10th site. Randomly, about half the time it would be the chromosome 10 he inher- ited from his mother and half the time the chromosome 10 he inherited from his father.

Since the particular member of each chromosome pair on a given gamete is random, some gametes have one chromosome of the pair, some have the other. Each person can produce 223 different gametes, more than 8 million versions of his or her own 46 chromosomes.

One in 8 million from the father’s gamete, which joins with one in 8 million from the mother’s gamete, is only the beginning of the vast diversity among humans. People also differ in genes, in triplets and pairs within genes, and in experiences from conception onward.

Matching Genes When conception occurs in the usual way, some of several mil- lion sperm find their way through the vagina, cervix, and uterus and then into a fallopian tube (oviduct), where it might find an ovum. After about an hour, the nucleus of one sperm meets the nucleus of the ovum, and they form a new living cell called a zygote. Two reproductive cells have literally become one, and that one new cell is unlike the cells of either parent.

The chromosomes from the father match up with the chro- mosomes from the mother, so that the zygote contains 23 pairs of chromosomes, arranged in father/mother pairs. The genetic information on those 46 chromosomes constitutes the organ- ism’s genetic inheritance, or genotype, which endures throughout life, repeated in almost every cell. (Sometimes a zygote has more or fewer than 46 chromosomes, a problem discussed later in this chapter.)

In 22 of the 23 pairs of human chromosomes, both chromo- somes are closely matched. Each of these 44 chromosomes is called an autosome, which means that it is independent (auto means self) of the sex chromosomes (the other 2).

Especially for Number Crunchers A hundred years ago, it was believed that humans had 48 chromosomes, not 46; 10 years ago, it was thought that humans had 100,000 genes, not 25,000. Why?

gamete A reproductive cell; that is, a sperm or ovum that can produce a new individual if it combines with a gamete from the other sex to make a zygote.

zygote The single cell formed from the fusing of two gametes, a sperm and an ovum.

genotype An organism’s entire genetic inheritance, or genetic potential.

The Genetic Code 63

The Moment of Conception This ovum is about to become a zygote. It has been pene- trated by a single sperm, whose nucleus now lies next to the nucleus of the ovum. Soon, the two nuclei will fuse, bringing together about 25,000 genes to guide development.

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Each autosome, from number 1 to number 22, contains hundreds of genes in the same positions and sequence, and each gene on each autosome matches with its counterpart from the other parent at conception. If the gene from one parent is exactly like the gene from the other parent, that gene pair is said to be homozygous (literally, “same-zygote”). The match is not always letter perfect, because the codes within a few genes vary slightly. A person with some differences between the code of one gene and that of its counterpart from the other parent is said to be heterozy- gous (“different-zygote”) for that trait.

Each version of a gene that has variations is called an allele. A person could have the same allele from each parent and be homozygous for that trait or have dif- ferent alleles and be heterozygous. Usually it does not matter which allele a person has, but some alleles are harmful, especially if the person inherits two of them.

Very rarely, a gene has no counterpart on the other autosome and that gene stands alone. But more than 99.9 percent of the genes on the 22 pairs of chromosomes find a match, usually a homozygotic match but sometimes a heterozygotic one.

Male or Female? The 23rd pair is a special case, because these are the sex chromosomes. In fe- males, the 23rd pair is composed of two large X-shaped chromosomes. Accord- ingly, it is designated XX. In males, the 23rd pair has one large X-shaped chromosome and one smaller Y-shaped chromosome. It is called XY.

Because a female’s 23rd pair is XX, every ovum contains either one X or the other—but always an X. And because a male’s 23rd pair is XY, half of his sperm carry an X chromosome and half a Y. The X chromosome is bigger and has more genes, but the Y chromosome has a crucial gene, called SRY, that directs a devel- oping fetus to make male organs. Thus, the sex of a baby depends on which kind of sperm penetrates the ovum—a Y sperm, creating a boy (XY), or an X sperm, cre- ating a girl (XX) (see Figure 3.2).

The natural sex ratio at birth is close to 50/50. (The actual ratio among new- borns in the United States is 52 males to 48 females.) This ratio can be affected by serious adversity, such as famine, when male fetuses are more likely to experi- ence spontaneous abortion (also called miscarriage), or by induced abortion, as the following explains.

allele A slight, normal variation of a particular gene.

23rd pair The chromosome pair that, in humans, determines the zygote’s (and hence the person’s) sex. The other 22 pairs are autosomes, the same whether the 23rd pair is for a male or a female.

XX A 23rd chromosome pair consisting of two X-shaped chromosomes, one each from the mother and the father. XX zygotes become female embryos, female fetuses, and girls.

XY A 23rd chromosome pair consisting of an X-shaped chromosome from the mother and a Y-shaped chromosome from the father. XY zygotes become male embryos, male fetuses, and boys.

spontaneous abortion The naturally occur- ring termination of a pregnancy before the embryo or fetus is fully developed. (Also called miscarriage.)

induced abortion The intentional termination of a pregnancy.

64 CHAPTER 3 ■ Heredity and Environment

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Mapping the Karyotype A karyotype portrays a person’s chromosomes. To create a karyotype, a cell is grown in a laboratory, magnified, and then usually photographed. The photo is cut into pieces and rearranged so that the matched pairs of chromosomes are lined up from largest (at top left) to small- est (at bottom right, fourth box from the left). Shown at the bottom right are the 23rd chromosome pair: XX for a female and XY for a male.

➤Response for Number Crunchers (from page 63): There was some scientific evidence for the wrong numbers (e.g., chimpanzees have 48 chromosomes), but the reality is that humans tend to overestimate many things, from the number of genes to their grades on the next test.

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The Genetic Code 65

OvaSperm

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FemaleFemaleMaleMale

44+ XX

44+ XX

44+ XY

44+ XY

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22+ Y

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Mother’s chromosomes 44+XX

Father’s chromosomes 44+XY

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22+ X

22+ X

22+ X

Possible Combinations of Sex Chromosomes

FIGURE 3.2

Determining a Zygote’s Sex Any given cou- ple can produce four possible combinations of sex chromosomes; two lead to female chil- dren and two, to male. In terms of the future person’s sex, it does not matter which of the mother’s Xs the zygote inherited. All that matters is whether the father’s Y sperm or X sperm fertilized the ovum. However, for X-linked conditions it matters a great deal, because typically one, but not both, of the mother’s Xs carries the trait.

Observation Quiz (see answer, page 66): In the chapter-opening photograph (p. 60), can you distinguish the Y sperm from the X sperm?

Too Many Boys?

Historically, wars, diseases, and famine sometimes killed many people before they could reproduce. Usually, more girls survived than boys. Because there were far more women than men, and the overall population was dwindling, some cultures encouraged polygamy or single motherhood. Some also allowed men to discard wives who bore no sons (England’s King Henry VIII divorced or executed five wives for this reason). Many pregnant women tried to ensure that they would have a boy by resorting to such folk customs as eating “hot” foods. These interventions worked—but only half the time!

Many contemporary cultures still favor boys. For example, in 1979, in an effort to halt starvation by slowing population growth, the government of China began forbidding Chinese couples to have more than one child. (This policy did not apply to members of minority groups or rural residents.) Poverty has been dramatically reduced in China over the two decades since then, but the policy has had one unexpected effect: too many boys. Many Chinese couples want their only child to be a boy because sons are expected to take care of their parents in old age. Millions of female fetuses were aborted, and thousands of newborn girls were made available for adoption. Since 1993, the Chinese government has prohibited prenatal testing solely to determine sex, but “the law has been spottily enforced” (French, 2005, p. 3). In the city of Guiyang, about 75 girls are born for every 100 boys (French, 2005).

Similar data come from other countries. In 1999, in Punjabi, India (where sex-selection laws similar to those in China have been enacted), only 79 females were born for every 100 males (Dugger, 2001). In Nepal, far more women use contraception after the birth of a son than a daughter (Leone et al., 2003), again skewing the sex ratio.

Is this imbalance a private matter or a public concern? Might a society with many males have more learning disabilities, drug abuse, violent crimes, wars, and suicides but fewer nurses, day-care centers, and family caregivers? Chinese doctors worry about the spread of AIDS if young men with no wives turn to risky sex (Cohen, 2004). The Chinese government now allows couples to have two children if both parents are “onlies.”

But wait. Gender does not determine behavior directly. Men do not have to abuse drugs or turn to prostitutes. Although women traditionally are caregivers, many single fathers and loving grandfathers provide excellent care of children, and many husbands and sons care for elderly women. In former times, cultures adjusted to having more girls; perhaps today they could adjust to having more boys. Or is there something better about a sex ratio that is close to 50/50?

Unlike China and India, most nations have no laws against sex selection, or about any other attempt to create “designer babies” —children who have the genes the parents prefer. Should they?

issues and applications

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SUMMING UP

The fusion of two gametes (sperm and ovum) creates a zygote, a tiny one-celled crea- ture that has the potential to develop into a human being. One way to describe that process is chemically: DNA is composed of four chemicals that pair up; three of those pairs (a triplet) direct the formation of an amino acid; amino acids in a particular sequence make up proteins; and proteins make a person. Another way to describe it is with numbers: The genetic code for a human being consists of about 3 billion base pairs on 25,000 genes on 46 chromosomes, half from the mother and half from the father. The father’s 23rd chromosome pair is XY, which means that half his sperm are X and half are Y; thus, the future baby’s sex is determined by which sperm penetrates the ovum and forms a zygote.

■

From One Cell to Many As already explained, when sperm and ovum combine into a zygote, they establish the genotype: all the genes that the developing person has. Creation of an actual person from one cell involves several complex processes of duplication of genetic information, cell division, and differentiation of cells into different types.

Some genes on the genotype are ignored and others amplified in the formation of the phenotype, which is the actual appearance and manifest behavior of the person. Let’s begin by describing the early development of that one original cell.

New Cells, New Functions Within hours after conception, the zygote begins duplication and division. First, the 23 pairs of chromosomes duplicate, forming two complete sets of the genome. These two sets move toward opposite sides of the zygote, and the single cell splits neatly down the middle into two cells, each containing the original genetic code. These two cells duplicate and divide, becoming four, which duplicate and divide, becoming eight, and so on.

By the time you (or I, or any other person) were born, your original zygote had become about 10 trillion cells. By adulthood, those cells had become more than 100 trillion. But no matter how large the total number, no matter how much divi- sion and duplication occur, almost every cell carries an exact copy of the complete genetic instructions inherited by the one-celled zygote. This explains why DNA testing of any body cell, even one from a drop of blood or a snip of hair, can iden- tify “the real father,” “the guilty criminal,” or “the long-lost brother.”

The fact that every cell in the embryo contains the developing human being’s complete genetic code does not mean that any cell could become a person—far from it. At about the eight-cell stage, a third process, differentiation, is added to duplication and division. Cells begin to specialize, taking different forms and reproducing at various rates, depending on where they are located. As one expert explains, “We are sitting with parts of our body that could have been used for thinking” (Gottlieb, 2002, p. 172).

As a result of this specialization and differentiation, very early in development cells change from being able to become any part of a creature to being able to become only one part—an eye or a finger, for instance. All cells carry the same genetic information, but cells take on new functions as needed and cannot switch back. An eyelash cannot become a fingernail, although both have the same instructions as the original cell that could have become an eyelash or a fingernail.

Certain genes switch on at particular times, a fact that helps us understand development because it explains why children should not be expected to act like

phenotype The observable characteristics of a person, including appearance, personality, intelligence, and all other traits.

66 CHAPTER 3 ■ Heredity and Environment

➤Answer to Observation Quiz (from page 65): Probably not. The Y sperm are slightly smaller, which can be detected via scientific analysis (some cattle breeders raise only steers using such analysis), but visual inspection, even magnified as in the photo, may be inaccurate.

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adults. One fascinating aspect of human genetics is that almost half of all human genes affect the brain, not other parts of the body. Genes not only develop neurological functions, they also activate specific aspects of cognitive development, such as the ability to think about abstractions or to plan ahead (Marcus, 2004), neither of which young children can do. Even learning a language begins with genetically trig- gered maturation of certain brain areas.

Keep in mind that “genes merely produce proteins, not mature traits” (Gottlieb, 2002, p. 164). In other words, the genotype instigates body and brain formation, but the phenotype (the visible traits and behaviors) depends on many genes and on the environment. A zygote might have the genes for becoming, say, a musical genius, but that potential will not be realized without the contributions of many other factors. Epigenesis (see Chapter 2) is pervasive.

Gene–Gene Interactions Conception brings together genetic instructions from both parents for every human characteristic. Exactly how do these instructions influence the specific traits that a given offspring inherits? The answer is quite complex, because most traits are polygenic—affected by many genes—and multifactorial—influenced by many factors.

The Human Genome Project is the international effort to map the human genome. Its researchers have found that humans have only about 25,000 genes, 99 percent of which are present in the genomes of other creatures as well. For ex- ample, the eyes of flies, mice, and people all originate from the Pax6 gene; another gene produces legs for a butterfly, a cat, a centipede, and a person.

The genetic similarity among living creatures might make you wonder what ac- counts for the differences. The genomes of humans and chimpanzees are more than 99 percent identical, so why are humans and chimps so different? The answer lies in the activities of 100 or so “regulator” genes, which influence thou- sands of other genes (Marcus, 2004). Regulator genes make a creature who talks, walks, and thinks as humans do, unlike other animals. Regulator genes regulate genetic interaction, and that makes all the difference.

Human brain size (about 1,400 cubic centimeters) is highly heritable and is quite similar among humans worldwide, especially when compared with the small brains (about 370 cubic centimeters) of our nearest relatives, the chimpanzees (Holden, 2006). Of course, bigger animals (elephants) have bigger brains, but the proportion of brain to body is significantly greater for humans than for other creatures.

Now we’ll look at some specifics of gene interaction, in those cases in which the genes exist in several versions (alleles).

Additive Heredity Some alleles are additive genes because their effects add up to influence the phenotype. When genes interact additively, the trait reflects the contributions of all the genes that are involved. Height, hair curliness, and skin color, for instance, are usually the result of additive genes. Indeed, height is affected by an estimated 100 genes, each contributing a small amount, some to make a person a little taller than average, some a little shorter (Little, 2002).

In modern nations, most people have ancestors of various heights, hair curliness, skin color, and so on, so their children’s phenotype may not reflect the parents’ phenotypes, although it always reflects their genotypes. My daughter Rachel (with the crooked little finger) is of average height, shorter than either my husband or I

From One Cell to Many 67

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Twelve of Three Billion Pairs This is a com- puter illustration of a small segment of one gene, with several triplets. Even a small difference in one gene, such as a few extra triplets, can cause major changes in the phenotype of a person.

polygenic Referring to a trait that is influenced by many genes.

multifactorial Referring to a trait that is affected by many factors, both genetic and environmental.

Human Genome Project An international effort to map the complete human genetic code. This effort was essentially completed in 2001, though analysis is ongoing.

additive gene A gene that has several alleles, each of which contributes to the final phenotype (such as skin color or height).

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but taller than either of her grandmothers. She apparently inherited some of her grandmothers’ genes for relatively short height from us.

How any additive trait turns out depends on all the genes (half from each parent) a child happens to inherit. All additive genes contribute something to the pheno- type. To make this more complex, genes interact with each other (called epistasis) to produce traits that no ancestor had (Grigorenko, 2003). For instance, the SRY gene on the Y chromosome adds hormones, and one effect of those hormones is to make the boy grow taller. That adds about three inches of height that would not be added if all the autosomes (which carry the height genes) were the same but the 23rd pair was XX instead of XY, so the person was a girl with no SRY.

Dominant–Recessive Heredity Some alleles are not additive. Of course, the fact that a particular allele is non- additive doesn’t matter with homozygotic pairs, because both genes provide the same instructions. It does matter for heterozygotic pairs. In one nonadditive form, alleles are said to interact in a dominant–recessive pattern, which occurs when one allele, the dominant gene, is more influential than the other, the recessive gene.

Sometimes the dominant gene entirely controls the characteristic. In this case, the recessive gene is carried on the genotype but has no obvious effect on the phe- notype. For example, blood type B is dominant and blood type O is recessive, which means that a person whose genotype is BO would have B blood type.

An additional factor with blood is Rh-positive or -negative. Rh-negative is re- cessive, so a person whose blood genotype is Rh-positive and Rh-negative would have Rh-positive blood. (Some of the complex relationships of blood genotype and phenotype are shown in Appendix A, p. A-3). For blood transfusion the phenotype, not the genotype, matters.

Blue eyes are determined by a recessive allele and brown eyes by a dominant one. Many recessive traits are not completely hidden. For example, a phenotype of hazel eyes hints at a recessive blue-eye gene.

A special case of the dominant–recessive pattern occurs with genes that are X-linked, located on the X chromosome. If an X-linked gene is recessive—as are the genes for most forms of color blindness, many allergies, several diseases, and some learning disabilities—the fact that it is on the X chromosome is critical (see Table 3.1).

Since the Y chromosome is much smaller than the X, an X-linked recessive gene almost always has no dominant counterpart on the Y. For this reason, reces- sive traits carried on the X chromosome affect the phenotypes of sons much more often than those of daughters (who have another X, which usually has the domi- nant normal gene). This explains, for instance, why males who have an X-linked disorder, such as color blindness, inherited it from their mothers.

More Complications As complex as the preceding explanation may seem, it simplifies genetic interac- tion by making genes appear to be separately functioning entities. But remember that genes merely direct the creation of 20 types of amino acids, which combine to produce thousands of proteins, which then form the body’s structures and direct biochemical functions. The proteins of each cell interact with other proteins, nu- trients, and toxins.

For any living creature, the outcome of these interactions is difficult to predict. A small alteration in the sequence of base pairs or several extra repetitions in one triplet may be inconsequential or may cascade to create a major problem. The consequences depend on dozens of factors, many of which are not yet understood (Kirkwood, 2003; Plomin & McGuffin, 2003).

dominant–recessive pattern The interaction of a pair of alleles in such a way that the phenotype reveals the influence of one allele (the dominant gene) more than that of the other (the recessive gene).

X-linked Referring to a gene carried on the X chromosome. If a boy inherits an X-linked recessive trait from his mother, he expresses that trait, since the Y from his father has no counteracting gene. Girls are more likely to be carriers of X-linked traits but are less likely to express them.

Especially for Future Parents Suppose you wanted your daughters to be short and your sons to be tall. Could you achieve that?

68 CHAPTER 3 ■ Heredity and Environment

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For example, although females are always XX, one of those X chromosomes is relatively inactive. It seems random whether the dominant X is the one from the mother or the father, and it is not known what the implications are. This is just one example of hundreds of newly discovered complications, especially for human development. To understand these complications, scientists look closely at twins and clones.

Twins Although every zygote is genetically unique (i.e., has a unique genotype) and most newborns are similarly unique, there is one human exception: monozygotic multi- ple births.

Rarely—about once in 250 conceptions—on the first day of development, cells not only duplicate but split completely apart, creating two, or four, or even eight identical, separate zygotes. They originate from one (mono) zygote. If each implants and grows, they become multiple births, usually monozygotic (MZ) twins (also called identical twins) but sometimes monozygotic quadruplets or even octuplets.

Because monozygotic twins originate from the same zygote, their genotype is the same, as are their genetic instructions for physical appearance, psychological traits, vulnerability to diseases, and everything else. One monozygotic twin can donate a kidney for surgical implantation in the other twin with no risk of organ rejection.

Remember that genes start development, affecting every trait, but environment (including chance) is crucial (Kirkwood, 2003). Monozygotic twins differ in birth- weight because of where in the mother’s uterus each happened to be. Parents treat twins differently, sometimes favoring the larger one, sometimes the smaller (Caspi et al., 2004; Piontelli, 2002).

When monozygotic twins differ in a genetic trait, that helps scientists recognize a nongenetic effect. For example, a pair of 13-year-old monozygotic twins, Brian and Jason, were raised together, which means that their nature (as MZ twins) is

monozygotic (MZ) twins Twins who origi- nate from one zygote that splits apart very early in development. (Also called identical twins.) Other monozygotic multiple births (for example, quadruplets) can occur as well.

From One Cell to Many 69

TABLE 3.1

The 23rd Pair and X-Linked Color Blindness

X indicates an X chromosome with the X-linked gene for color blindness

23rd Pair Phenotype Genotype Next Generation Normal woman

Normal man

Normal woman

Normal woman

Color-blind man

Color-blind woman (rare)

1. XX

2. XY

3. XX

4. XX

5. XY

6. XX

Not a carrier

Normal X from mother

Carrier from father

Carrier from mother

Inherited from mother

Inherited from both parents

No color blindness from mother

No color blindness from father

Half her children will inherit her X. The girls with her X will be carriers; the boys with her X will be color-blind.

Half her children will inherit her X. The girls with her X will be carriers; the boys with her X will be color-blind.

All his daughters will have his X. None of his sons will have his X. All his children will have normal vision, unless their mother also had an X for color blindness.

Every child will have one X from her. Therefore, every son will be color-blind. Daughters will be only carriers, unless they also inherit an X from the father, as their mother did.

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identical and much of their environment is shared. Both have Asperger syndrome (explained in Chapter 11). However, Asperger’s makes Brian shy and socially awk- ward, in ways that are quite common for 13-year-olds. He probably would not have been diagnosed were it not for Jason, who displays much more noticeable symptoms of Asperger syndrome—he “fails miserably” in social interaction and his “stilted conversations typically include inappropriate questions and comments” (Bower, 2006, p. 106). Why is one monozygotic twin so much more impaired than the other? Probably because Brian breathed normally at birth, but Jason did not breathe for several seconds until doctors administered oxygen. That loss of oxygen impaired his brain. These boys show that nature matters (both have Asperger’s) but that nurture does as well.

Most twins (about two-thirds) are dizygotic (DZ) twins, also called fraternal twins. They began life as two separate zygotes created by the fertilization of two ova by two sperm at roughly the same time. (Usually, only one ovum is released per month, but sometimes two or more ova become available for fertilization.)

The incidence of dizygotic twins varies by ethnicity and age. For example, DZ twins occur about once in every 11 births among Yoruba women from Nigeria; once in 100 births among British women; and once in 700 births among Japanese women (Gall, 1996; Piontelli, 2002). Women in their late 30s are three times as likely to have DZ twins as are women in their early 20s.

Like all siblings from the same parents, DZ twins have about half of their genes in common. And like any other siblings, they can differ markedly (including in whether they are male or female) or they can look quite similar. Some look so much alike that only genetic tests can determine whether they are monozygotic or dizygotic.

Clones A clone is an organism that is produced from another organism through artificial replication of cells and is genetically identical to that organism. Unlike mono- zygotic twins, which occur naturally, clones are artificially created. Cloning of animals involves removing a cell from a living creature and making it develop into another, genetically identical creature. Since every cell of an organism carries the entire genetic code, cloning is theoretically possible for all living things.

Cloning is routine with plants but is difficult with animals; more than 99 per- cent of all cloning attempts with animals have failed. The most famous successful animal clone was a sheep named Dolly, created in Scotland in 1997 when a cell

dizygotic (DZ) twins Twins who are formed when two separate ova are fertilized by two separate sperm at roughly the same time. (Also called fraternal twins.)

clone An organism that is produced from another organism through artificial replica- tion of cells and is genetically identical to that organism.

70 CHAPTER 3 ■ Heredity and Environment

Same Birthday, Same (or Different?) Genes Twins who are of different sexes or who have obvious differences in personality are dizygotic, sharing only half of their genes. Many same- sex twins with similar temperaments are dizygotic as well. One of these twin pairs is dizygotic; the other is monozygotic.

Observation Quiz (see answer, page 72): Can you tell which pair is monozygotic?

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in vitro fertilization (IVF) Fertilization that takes place outside a woman’s body (as in a glass laboratory dish). Sperm are mixed with ova that have been surgically removed from the woman’s ovary. If the combination produces a zygote, it is inserted into the woman’s uterus, where it may implant and develop into a baby.

infertility The inability to produce a baby after at least a year of trying to conceive via sexual intercourse.

assisted reproductive technology (ART) A general term for the techniques designed to help infertile couples conceive and then sustain a pregnancy.

From One Cell to Many 71

from the mammary gland of one ewe was chemically induced to begin duplicating; the embryo was then implanted in the uterus of another ewe. Dolly was the only live birth that resulted from 434 cloning attempts. She aged rapidly and died at age 6, young for a ewe. The scientists who created her have described the hazards of cloning (Wilmut & Highfield, 2006).

Mice are the only mammals that are successfully cloned, time and again. Many other research techniques—including interbreeding, cross-breeding, knocking out genes (disabling a gene to learn its function), and drug dosing—that are unethical with people and that would take years with most animals are used with mice. Mice are helping social scientists learn how to reverse addiction (Crabbe, 2003) and prevent mental illness (Williams, 2003).

For ethical reasons, cloning of humans is illegal, although cloning of cells (not whole organisms) is part of research on many human diseases. Technically, human clones would be possible via in vitro fertilization (IVF). Ova are surgically re- moved from a woman and mixed with sperm. If fertilization occurs, viable zygotes begin to duplicate in vitro, which literally means “in glass” (i.e., a glass laboratory dish). In duplication, sometimes one cell is removed to test for abnormal genes (done only for serious genetic conditions); if the severe condition is not found, the remaining cells are inserted into the woman’s uterus to develop into a healthy baby. This is not cloning, and doing so raises no ethical issues.

It is theoretically possible, with IVF, to extract one of those early cells, allow it to duplicate and divide, insert both groups of cells into a woman, and hope that both will implant. This would result in monozygotic twins, a form of cloning that is illegal.

Not at all illegal is the usual in vitro fertilization method. After several zygotes are created and reach the 4- or 8-cell stage, the developing cells are inserted into the uterus. About a third of the time, at least one zygote implants and develops into a baby. Almost half of those times, two or more cell masses implant, and twins or other multiples occur (Society for Assisted Reproductive Technology & American Society for Reproductive Medicine, 2002).

Assisted Reproduction Depending primarily on age, between 2 and 30 percent of all couples are troubled by infertility, defined as the inability to produce a baby after at least a year of trying. The lowest rates of infertility are among emerging adults (age 18–25) who have avoided drugs and sexually transmitted diseases and who live in medically advanced nations; the highest rates worldwide are probably among older couples in South Africa. About one-third of all infertility originates with the woman and one-third with the man; the other one-third is of unknown origin. Counseling, as well as med- ical intervention, usually includes both partners (Covington & Burns, 2006).

In developed nations, infertile couples often turn to assisted reproductive technology (ART). One simple treatment for some female infertility is to use drugs to cause ovulation. For male infertility, sperm from a donor may be inserted into the female partner’s uterus, a process called artificial insemination, which has been in use for 50 years.

Increasingly common are various techniques that begin with in vitro fertilization, as just described. Although failure is more common than success, a million IVF children (more than half of them twins or triplets) have been born in 40 nations since the first “test-tube” baby was born in England in 1978 (Gerris et al., 2004). The usual reason for IVF is that a woman fails to ovulate or has blocked fallopian tubes. Another reason is low sperm production, which is overcome by injecting a single viable sperm into an ovum (Bentley & Mascie-Taylor, 2000).

Many methods for overcoming infertility result in multiple births. In the United States, triplet births have increased by 500 percent since 1980, according

➤Response for Future Parents (from page 68): Yes, but you wouldn’t want to. You would have to choose one mate for your sons and another for your daughters, and you would still have to use sex-selection methods. Even so, it might not work, given all the genes on your genotype. More important, the effort would be unethical, unnatural, and possibly illegal.

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to the Center for Health Statistics, and twin births have almost doubled (U.S. Bureau of the Census, 2004). Many couples who thought they could never have any children now have two or three, to the delight of some parents but not of physicians (Newton et al., 2007). (ART is further discussed in Chapter 20.)

72 CHAPTER 3 ■ Heredity and Environment

“I Am Not Happy with Me”

Successful IVF produces several zygotes. All could be inserted; some could be frozen for later use; some could be used for re- search; or some could be discarded. Each option is permitted by some nations, clinics, and couples and forbidden by others (Jones & Cohen, 2001). One factor in deciding which option to use is cost: In the United States, each IVF attempt costs about $12,000, with no guarantee of success. Some couples travel to nations with lower costs; others hope to improve their odds by having several zygotes implanted (Newton et al., 2007).

Implantation of more than one zygote creates problems, however. For humans, birthing more than one baby is hazardous for both mother and newborns. Complications of pregnancy, in- cluding high blood pressure and toxemia, are common, and mul- tiples are almost always born small and early—twins three weeks early on average, triplets six weeks, and quadruplets nine weeks.

Generally, the more embryos that develop together, the smaller, less mature, and more vulnerable each one is. Through- out life, multiples have higher rates of early death, disease, and disabilities. Triplets, for example, produce more stress in their parents, develop language more slowly, and form weaker social bonds than do equally small single babies or twins (Feldman & Eidelman, 2004).

Since fertility treatments are one cause of multiples, Finland allows only two zygotes to be implanted after in vitro fertiliza- tion. The limit is three in Norway and four in several other na- tions. In Belgium, the government pays only for single-embryo transfers, a policy that has reduced the rate of twins by half

(Ombelet, 2007). The United States has no legal limit, but many doctors recommend selective abortion if multiple embryos begin to develop.

ART can separate biological parenthood from child rearing. IVF can be done with donated sperm and ova, with the resulting embryos growing in the uterus of another woman, who can allow yet another couple to adopt the newborn. At birth, that infant already has five “parents.” Is that ethical?

Perhaps all ART is unethical, when thousands of children with special needs await loving adoptive parents. When I sug- gested this to a friend who was infertile, she called me “insensi- tive, arrogant, and ignorant” because my children had been easily conceived. She said it was no more ethical of me to con- ceive naturally than for her to use ART. Since then I have read the words of many infertile women. One wrote:

I just cannot imagine ever feeling good about anything again. I do not even know if my husband will stay with me when he realizes that children are not an option for us. My guess is he will find someone else who will be able to give him a baby. Since I cannot do that, I cannot imagine that he would be happy with me. I am not happy with me.

[quoted in Deveraux & Hammerman, 1998]

Complex social issues collide with the personal urge to pro- create (Covington & Burns, 2006; Dooley et al., 2003). Compas- sionate, thoughtful people, including many developmentalists, disagree.

in person

SUMMING UP

A person’s genotype influences almost every characteristic. Genes interact additively, recessively, and in many other ways; almost every trait is polygenic. Human diversity is guaranteed not only by the process of gamete formation and conception but also by life experiences. Each zygote is unlike any other ever conceived; diversity becomes even greater.

Most twins are dizygotic, with no more genes in common than any other siblings. About a third are monozygotic, developing from one zygote and hence having the same genotype. Clones also have the same genotype as the creature they are derived from, but cloning is illegal for humans and problematic for other animals. Some infertile cou- ples turn to assisted reproductive technology (ART) to conceive.

■

➤Answer to Observation Quiz (from page 70): The Japanese American girls are the monozygotic twins. If you were not sure, look at their teeth, their eyebrows, and the shape of their faces, compared with the ears and chins of the boys.

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carrier A person whose genotype includes a gene that is not expressed in the pheno- type. Such an unexpressed gene occurs in half of the carrier’s gametes and thus is passed on to half of the carrier’s children, who will most likely be carriers, too. Gen- erally, only when the gene is inherited from both parents does the characteristic appear in the phenotype.

From Genotype to Phenotype The main goal of this chapter is to help every reader grasp the complexity of the interaction between genotype and phenotype. Hundreds of scientists in many nations have studied thousands of twins, both monozygotic and dizygotic, raised together in the same home and raised separately in different homes. When this re- search began, scientists assumed that monozygotic twins reared together would share both genes and environment and that monozygotic twins raised apart would have the same genes but contrasting environments. This assumption led scientists to hope that twin studies would allow them to distinguish genetic influences from environmental ones (e.g., Segal, 1999).

Members of the next generation of scientists were skeptical. They undertook more research—on stepsiblings, adopted siblings raised together, biological sib- lings raised apart, and all kinds of twins raised in all kinds of homes (e.g., Reiss et al., 2000; see Research Design). They benefited from molecular analysis, mouse genomes, linkage analysis, and many other methods developed not only to treat physical illness but also used to understand inheritance of psychological traits. They discovered four generalities that virtually all developmentalists accept:

1. Genes affect every aspect of human behavior, including social and cognitive behavior.

2. Most environmental influences on children raised in the same home are not shared.

3. Each child’s genes elicit other people’s responses, and these responses shape development. In other words, a child’s environment is partly the result of his or her genes.

4. Children, adolescents, and especially adults choose environments that are compatible with their genes (called niche-picking), and thus genetic influences increase in adulthood.

[Ellis & Bjorklund, 2005; Plomin et al., 2003; Posthuma et al., 2003]

As you learn more about the interactions among genetic and nongenetic influ- ences, remember to distinguish between a person’s genotype, or genetic potential, and his or her phenotype, the actual expression of that genetic inheritance in phys- ical appearance, health, intelligence, and actions.

Everyone has many genes in his or her genotype that are not expressed in the phenotype. In genetic terms, each person is a carrier of unexpressed genes; that is, a person might “carry” an allele on his sperm or her ova and transmit it to off- spring. Only rarely does one gene, or even one pair, cause an identifiable disorder (some instances are described later in this chapter), but combinations of genes might affect the phenotype, additively or in some other way. Schizophrenia, for instance, probably results from many genes, and one reason for the varied types, severity, and developmental patterns of schizophrenia is that each person has a different combination of genes. Each person also has unique experiences, of course, and that difference also affects every mental illness.

About half of all genes affect the brain, not the rest of the body. Thus, personal- ity patterns and cognitive skills are affected by thousands of genetic combinations, with each gene having the potential for small but measurable effects. The specifics depend on other genes, on family, and on culture (Vogler, 2006). A team of eight scientists who are working to decipher the coding variations of 11 million alleles (called the Hapmap Project) put it this way:

Many different genes distributed throughout the human genome contribute to the total genetic variability of a particular complex trait, with any single gene accounting for no more than a few percent of the overall variability.

[Hinds et al., 2005, p. 1079]

From Genotype to Phenotype 73

Research Design Scientists: David Reiss, Jenae M. Neiderhiser, E. Mavis Hetherington, and Robert Plomin.

Publication: The Relationship Code (Harvard University Press, 2000), as well as many journals.

Participants: 720 families, each with two children aged 10–18 with varied genetic links: monozygotic twins, dizygotic twins, full siblings, half siblings, and unrelated siblings with biological and stepparents.

Design: Dozens of checklists, inter- views, and observations, including longitudinal measures, were used to in- dicate emotions and cognitive abilities of parents and adolescents, as well as their interactions. Extensive analysis was undertaken to distinguish genetic and environmental effects.

Major conclusion: Genes have a strong impact on every characteristic, but fam- ily structure and parental style modify genetic influence.

Comment: By including siblings with so many kinds of relationships to each other and to their parents, with multi- ple, longitudinal measures, this study untangles some complex nature– nurture interactions.

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Thus, when something is “genetic,” that does not mean that its genetic origins are substantial, fixed, or unalterable. It means that it is part of a person’s basic foundation, affecting many aspects of life but determining none (T. D. Johnston & L. Edwards, 2002). Rachel’s little finger, mentioned in the chapter’s opening, was the product of genes, but it might have not been crooked if her prenatal environ- ment had been different.

Every trait, action, and attitude has a genetic component: Without genes, no behavior could exist. But without environment, no gene could be expressed. Now we examine two complex traits: addiction and visual acuity. As you read about two specific expressions (alcoholism and nearsightedness) of those traits, you will see that understanding the progression from genotype to phenotype has many practi- cal uses.

Addiction At various times, drug addiction, including alcoholism, has been considered a moral weakness and a personality defect. Addicts were locked up in jails or in mental institutions. Some nations tried to stop alcoholism by making alcohol illegal, as the United States did from 1919 to 1933, and most nations have laws forbidding certain drugs and taxes to discourage use of other drugs.

Nonaddicts have long wondered why addicts don’t just quit. Now we know that inherited biochemistry makes people vulnerable to various addictions. Anyone can abuse drugs and alcohol, but genes create an addictive pull that can be overpower- ing, extremely weak, or somewhere in between (Heath et al., 2003).

Alcoholism, particularly, has been studied for decades (Agarwal & Seitz, 2001). The brain patterns of alcoholics’ sons who have never consumed alcohol differ from sons of nonalcoholics. The way a person’s body digests and metabolizes alco- hol allows some people to “hold their liquor” without getting sick and therefore to drink too much; it causes others, notably many East Asians, to sweat and become red-faced after just a few sips. This embarrassing response is one reason many Asians avoid alcohol (Heath et al., 2003).

74 CHAPTER 3 ■ Heredity and Environment

Shyness Is Universal Inhibition is a psycho- logical trait that is influenced by genetics. It is more common at some ages (late infancy and early adolescence) and in some gene pools (natives of northern Europe and East Asia) than others. But every community in- cludes some individuals who are unmistak- ably shy, such as this toddler in Woleai, more than 3,000 miles west of Hawaii.

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Too Cute? This portrait of the Genain sisters was taken 20 years before they all developed schizophrenia. However, from their identical hair ribbons to the identical position of their feet, it is apparent that their unusual status as quadruplets set them apart as curiosities. Could their life in the spotlight have nurtured their potential for schizophrenia? There is no way to know for sure.

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Among people of all ethnicities, reactions to alcohol vary, just as reactions to prescription drugs or many foods vary. Some drinkers become sleepy, others nau- seated, others aggressive, and others euphoric. Each of these reactions makes that person more, or less, likely to have another drink.

Alcoholism is not simply biochemical. As with all addictions, it is psychological as well. Certain personality traits (a quick temper, a readiness to take risks, and a high level of anxiety) make it more likely that a person will drink and use drugs (Bau et al., 2001; Nielsen et al., 1998). Certain contexts, such as many fraternity parties, make it hard not to drink; other contexts, such as a church in a “dry” county, make it hard to drink.

Gender also mitigates or increases alcoholism, depending on culture. For biolog- ical reasons (body size, fat composition, genes for metabolism), women become drunk on less alcohol than men do. In Japan, although women have the same genes as men for metabolizing alcohol, they drink only about a tenth as much. When Japanese women live in the United States, their average alcohol consumption increases about fivefold (Higuchi et al., 1996).

Thus, culture is crucial. If people inherit genes that predispose them to alco- holism but live where alcohol is unavailable (in rural Saudi Arabia, for example), the genotype will never be expressed in the phenotype. Similarly, if alcohol-prone children grow up where alcohol abounds but belong to a religious group that forbids it (such as Seventh-Day Adventists in California), they may escape their genetic destiny. Nature and nurture create the alcoholic.

Visual Acuity Almost every factor that affects overall development also affects vision. Remember that we study change over the life span. People see differently depending on their age:

■ Newborns cannot focus more than 2 feet away. ■ Children see better each year until about age 8. ■ Many adolescents become nearsighted when eyeball shape changes. ■ Vision is more likely to improve than to worsen until about age 40. ■ In middle age, the elasticity of the lens decreases and the eyeball shape changes

again, so that many people become farsighted and need reading glasses. ■ Among the old, eye diseases, including cataracts, are common. ■ About 10 percent of people over age 90 are blind.

Especially for People Who Are Easily Bored Is your wish for excitement likely to lead to addiction?

From Genotype to Phenotype 75

Especially for College Students Who Enjoy a Party You wonder if one of your male friends is an alcoholic because he sometimes drinks too much. He may be OK, though, because he can still talk clearly after drinking twice as much as you do. What should you ask him?

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Early Death or Long Life? Jerzy Skibo is a Polish farmer pausing to enjoy his lunch of sausage, cheese, and wine. This diet could be unhealthy if he is genetically vulnerable to heart disease or alcoholism. Or he might have protective genes and live to age 100, as some Polish farmers do.

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Nearsightedness and Genes Children usually see quite well, but if they do have a vision problem it is most often nearsightedness (also called myopia). Nearsightedness is a symptom in more than 150 genetic syndromes (Morgan, 2003). It may also be caused by physical trauma or illness (such as the rubella virus that caused my nephew David’s cataracts; see Chapter 1) or by poor nutrition (such as vitamin A deficiency). Most of these factors cause “high” nearsightedness, so severe that it can lead to blindness.

What about the more common “low” nearsightedness, which makes it hard to read signs that are too far away? A study of British twins found that the Pax6 gene, which governs eye formation, has many alleles that make people somewhat near- sighted (Hammond et al., 2004). This research found heritability of almost 90 per- cent, which means that if one monozygotic twin is nearsighted, the other twin will almost always be nearsighted, too.

From this and other research, it is evident that genes affect vision. Eye shape is genetic and familial as well as age-related.

Culture and Cohort If the science of human development arose from the study of only one cohort or culture (such as, in this case, contemporary Britons), scientists might conclude that genes were the major cause of poor vision (Farbrother & Guggenheim, 2001). However, historical and multicultural research finds that environment powerfully influences nearsightedness as well.

The most dramatic example is that if a child’s diet is deficient in vitamin A, then he or she will not be able to see well. More than 100,000 African children have partial vision or are blind, for that very reason (West & Sommer, 2001). In their case, genes are irrelevant: The environmental cause and the solution (sup- plemental vitamin A) are clear.

But what about well-nourished children? Barring trauma or illness, is their visual acuity entirely genetic? Cross-cultural research indicates that it is not.

In Singapore, Taiwan, and Hong Kong, myopia has recently increased so much that the surge has been called an epidemic. The first published research on this phenomenon appeared in 1992, when scholars noticed that, in army-mandated medical exams of all 17-year-old males in Singapore, 43 percent were nearsighted

76 CHAPTER 3 ■ Heredity and Environment

Young Scholars In Japan and other countries of East Asia, the incidence of nearsightedness is increasing at a rapid rate. One reason may be the amount of time children in those cultures spend indoors studying, which far exceeds the time spent by children in Western societies. HA

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➤Response for People Who Are Easily Bored (from page 75): It depends on you. Some people who love risk become addicts; others develop a healthy lifestyle that includes adventure, new people, and exotic places. Any trait can lead in various directions.

➤Response for College Students Who Enjoy a Party (from page 75): Your friend’s ability to “hold his liquor” is an ominous sign; his body probably metabolizes alcohol differently from the way most other people’s do. Alcoholics are often deceptive about their own drinking habits, so you might ask him about the drinking habits of his relatives. If he has either alcoholics or abstainers in his family, you should be concerned, since both patterns are signs of a genetic problem with alcohol. Ask your friend whether he could have only one drink a day for a month. Alcoholics find such restricted drinking virtually impossible.

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in 1990 compared with only 26 percent a decade earlier (Tay et al., 1992). Further studies found that nearsightedness increased in Taiwan between ages 6 and 17 from 12 to 84 percent; in Singapore between ages 6 and 9 from 28 to 44 percent; in Hong Kong between ages 7 and 10 from 10 to 60 percent (cited in Grosvenor, 2003). These studies occurred in many circumstances and decades, but the trend was the same.

These increases are partly developmental (remember that nearsightedness in- creases with puberty), and perhaps some of the young children were already near- sighted but had not yet been diagnosed. Thus, some scholars are not ready to conclude that “myopia is increasing at an ‘epidemic’ rate, particularly in East Asia” (Park & Congdon, 2004, p. 21).

However, these increases are far higher than they are among children outside East Asia. Further, parents of these same children are much less nearsighted. This suggests an environmental cause (Morgan, 2003; Saw, 2003). What could it be?

One possible culprit is cited again and again: the increasing amount of time children spend studying. In Chapter 12 you will learn that East Asian children are amazingly proficient in math and science, and one reason is that they spend more time doing schoolwork than Western children do. As their developing eyes focus on the pages in front of them, they may lose acuity for objects far away—which is exactly what nearsightedness means. Ophthalmologists suggest that if these chil- dren spent more time outside playing, walking, or relaxing in regular daylight, fewer might need glasses (Goss, 2002; Grosvenor, 2003).

As one expert concludes, “The extremely rapid changes in the prevalence of myopia and the dependence of myopia on the level of education indicate that there are very strong environmental impacts” on Asian children’s vision (Morgan, 2003, p. 276). Genes are crucial, of course, but it is not surprising that myopia, alco- holism, and almost every other complex human characteristic are highly heredi- tary and highly environmental.

Practical Applications Some developmental applications of the nature–nurture interaction are obvious. Knowing that genes affect every disorder keeps parents from putting all the blame on their child or their parenting. Knowing that there is a family history of a genetic problem or, better yet, that someone inherited a problem can lead to practical steps. For instance, if alcoholism is in the genes, parents can avoid drinking and their children can be kept away from alcohol. If nearsightedness runs in the fam- ily, parents can make sure that children spend time each day playing outdoors.

Of course, nondrinking and outdoor play are recommended for every child, as are dozens of other behaviors, such as flossing the teeth, saying thank you, getting enough sleep, eating vegetables, and writing thank-you notes. However, no child can do everything, and no parent can enforce every proper action. Awareness of genetic vulnerability helps parents set priorities, avoid blame, and take constructive action.

To illustrate, consider one more epidemic. In type 2 diabetes (once called adult-onset diabetes), the body’s production of insulin gradually becomes less effi- cient. In the United States in 2004, diabetes was the sixth most common cause of death, and it is estimated that 1 in 3 children who were born in 2000 will develop diabetes (Lazar, 2005).

Type 2 diabetes is increasing in the United States, partly because obesity leads to expression of the genetic vulnerability (Schwartz & Porte, 2005). Figure 3.3 depicts this, based on data reported in MMWR (see Research Design). Some eth- nic groups (African Americans, Hispanic Americans, and many Native Americans)

type 2 diabetes A chronic disease in which the body does not produce enough insulin to adequately metabolize carbohydrates (glucose). It was once called adult-onset diabetes because it typically developed in people aged 50 to 60; today, however, it often appears in younger people.

From Genotype to Phenotype 77

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are genetically more vulnerable to diabetes. One reason is that they may have a “thrifty gene” that protected their ancestors in times of famine (Lazar, 2005) but that encourages the accumulation of body fat when food is plentiful (Hildyard & Wolfe, 2002).

Worldwide, the incidence of diabetes is expected to double by 2025, when 300 million people will have the disease (Kiberstis, 2005). The United States now has a childhood obesity epidemic (see Chapter 11), and some adolescents already have type 2 diabetes (Kiberstis, 2005). Knowing this, parents who have diabetic relatives can redouble their efforts to encourage healthy eating and exercise in their children (and themselves). Once again, understanding the interaction be- tween nature and nurture can prevent or moderate genetic problems.

SUMMING UP

Genes affect every trait—whether it be something wonderful, such as a wacky sense of humor; something fearful, such as a violent temper; or something quite ordinary, such as the tendency to be bored. The environment affects every trait as well, in ways that change as maturational, cultural, and historical processes unfold. The expression of genes can sometimes be directed or deflected, depending on the culture and the soci- ety and even on the individual and the family. This is apparent in alcoholism, nearsight- edness, and type 2 diabetes, all of which have strong genetic roots, distinctive developmental patterns, and environmental triggers. Genes are always part of the story, influential on every page, but they never determine the plot or the final paragraph.

■

78 CHAPTER 3 ■ Heredity and Environment

Percent of overall

population

Obese – Body mass index (BMI) over 30*

30

25

20

15

10

5

0

19 91

19 93

19 95

19 97

19 99

20 01

20 03

20 04

Year

Diabetic – Diagnosed by a health professional

* For calculation of BMI, see Table 17.3.

Source: MMWR, July 14, 2006, and August 22, 2003.

FIGURE 3.3

Getting Worse Obesity is often associated with diabetes, but some people are geneti- cally protected, which means that they can be seriously overweight but disease-free. The graph illustrates that, while obesity and diabetes are both on the rise, the rate of obesity is far higher and is increasing more rapidly than that of diabetes. Detailed data suggest that obesity is often the trigger for the genetic risk of diabetes, but the two conditions do not automatically go hand in hand.

Research Design Scientists: Hundreds at the U.S. Centers for Disease Control and Prevention.

Publication: MMWR (Morbidity and Mortality Weekly Report), July 14, 2006.

Participants: Adults living in the United States, contacted by random telephone dialing.The participants had to be over age 18 and willing to answer questions. In 2004, 303,822 (about half those con- tacted) were interviewed.

Design:This is a repeated, cross- sectional study, interviewing thousands in every state. Standard questions are asked about many health-related behav- iors and conditions. Obesity is calculated based on the person’s self-reported height and weight.

Major conclusion: Many people have health problems, including almost two- thirds who are overweight many who are diabetic.

Comment:This huge national survey has been repeated over 25 years, with efforts to assure validity. However, people may underreport their weight, diabetics may not be diagnosed, no interviewees are in institutions (e.g., prisons and hospitals), and only people with phones who agree to talk are included. So the rates of obesity and diabetes may be even higher than de- picted in Figure 3.3.

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Chromosomal and Genetic Abnormalities We now focus on abnormalities that are caused by an identifiable problem, such as an extra chromosome or a single gene. Such abnormalities are relevant to our study of development for three reasons:

■ They provide insight into the complexities of nature and nurture. ■ Knowing their origins helps limit their effects. ■ Information combats the prejudice that surrounds such problems.

Information is needed as much for the families as for the individuals. Infants born with genetic and chromosomal problems are much more likely to live into adult- hood than was the case a few decades ago. This development raises emotional and cognitive issues for their parents and siblings that are not yet well understood (Lewis et al., 2006).

Not Exactly 46 Chromosomes Gametes with more or fewer than 23 chromosomes are formed for many reasons, both inherited and environmental (such as a parent’s exposure to excessive radia- tion). The variable that most often correlates with chromosomal abnormalities is the age of the mother. Paternal age (if a father is over age 40) is also relevant, but maternal age is more crucial (Crow, 2003), presumably because a woman’s ova (which begin to form before she is born) become increasingly fragile by midlife.

Chromosomal abnormalities occur not only in the formation of gametes but also in their early duplication. In those instances, cells of one person may have more or fewer than 46 chromosomes, while other cells of that person have exactly 46. The result is someone who is mosaic—that is, who has a mixture of normal and abnormal cells.

Zygotes often have too many or too few chromosomes. One scientist estimates that only half of all conceptions have the usual 46 (Borgaonkar, 1997). Most ab- normal zygotes do not duplicate, divide, and differentiate (K. L. Moore & Persaud, 2003). Those that start to grow usually are spontaneously aborted early in preg- nancy; other such embryos are aborted by choice when the parents learn about the condition. If a fetus survives to be born, birth is hazardous: About 5 percent of stillborn (dead-at-birth) babies have more than 46 chromosomes (O. J. Miller & Therman, 2001).

Once in about every 200 births, a live infant is born with 45, 47, or, rarely, 48 or 49 chromosomes. Each abnormality leads to a recognizable syndrome, a cluster of distinct characteristics that tend to occur together. Usually the cause is three chromosomes (a condition called a trisomy) at a particular location instead of the usual two.

Down Syndrome The most common extra-chromosome condition is Down syndrome, also called trisomy-21 because everyone with Down syndrome has three copies of chromo- some 21. The chances that a baby will be born with Down syndrome increase with the mother’s age. According to one estimate, a 20-year-old woman has about 1 chance in 800 of carrying a fetus with Down syndrome; a 39-year-old woman, 1 in 67; and a 44-year-old woman, 1 in 16 (see Appendix A, p. A-3). A few decades ago, infants with Down syndrome usually died in early childhood (usually of heart ail- ments), but now most survive to adulthood.

Some 300 distinct characteristics can result from the presence of that extra chromosome 21. No individual with Down syndrome is quite like another, either

mosaic Having a condition (mosaicism) that involves having a mixture of cells, some normal and some with an odd number of chromosomes or a series of missing genes.

Down syndrome A condition in which a per- son has 47 chromosomes instead of the usual 46, with three rather than two chro- mosomes at the 21st position. People with Down syndrome typically have distinctive characteristics, including unusual facial fea- tures, heart abnormalities, and language difficulties. (Also called trisomy-21.)

Chromosomal and Genetic Abnormalities 79

Is She the Baby’s Grandmother? No. Women over age 40 now have a higher birth rate than women that age did just a few decades ago. Later-life pregnancies are more likely to involve complications, but the out- come is sometimes what you see here: a gray-haired mother thrilled with her happy, healthy infant.

GE TT

Y (T

AX I)

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in symptoms or in severity, for three reasons: (1) Some are mosaic, having some cells with 46 chromosomes and others with 47; (2) sometimes only part of that third chromosome is present, so the person has, say, 461⁄4 chromosomes; (3) genes on other chromosomes and environmental experiences differ for each person, so genes on other chromosomes affect that 21st trio.

Despite this variability, most people with trisomy-21 have specific facial characteristics—a thick tongue, round face, slanted eyes—as well as distinctive hands, feet, and finger- prints. Many also have hearing problems, heart abnormali- ties, muscle weakness, and short stature. They are usually slower to develop intellectually, especially in language (Cohen, 2005). Their eventual intellect varies: Some are se- verely retarded; others are of average or even above-average intelligence.

Many young children with trisomy-21 are sweet-tempered, less likely to cry or complain than other children. This may become a liability if a child with Down syndrome gets less adult attention and thus less opportunity to learn (Wishart, 1999).

Adults with Down syndrome age faster than other adults, with the ailments of aging usually beginning at about age 30. By middle adulthood, they “almost invari- ably” develop Alzheimer’s disease, which severely impairs their communication skills and makes them much less compliant (Czech et al., 2000). They may de- velop other problems as well.

This generally pessimistic description, however, does not reflect the actual ex- perience of individuals with Down syndrome. Language does not come easily for them, and many have medical problems. But they may still become happy, proud, and successful young adults. One advised others:

You may have to work hard, but don’t ever give up. Always remember that you are important. You are special in your own unique way. And one of the best ways to feel good about yourself is to share yourself with someone else.

[Christi Todd, quoted in Hassold & Patterson, 1999]

80 CHAPTER 3 ■ Heredity and Environment

AP P

HO TO

/ AL

EX AN

DE R

ZE M

LI AN

IC HE

N KO

Universal Happiness All young children delight in painting brightly colored pictures on a big canvas, but this scene is unusual for two reasons: Daniel has trisomy-21, and this photograph was taken at the only school in Chile where normal and special-needs children share classrooms.

RE UT

ER S

/ C LA

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Great Theater A leading man named Sergei Makarov, shown here acting in a Gogol play, is extraordinarily talented. He is a member of Moscow’s Theater of Simple Souls, all of whom have Down syndrome. Does “simple souls” evoke pity? No need; a film starring Makarov won the top prize in Russia’s national film festival in 2006.

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Abnormalities of the 23rd Pair Every human has at least 44 autosomes and one X chromosome; an embryo can- not develop without an X. However, about 1 in every 500 infants has only one X and no Y (the X stands alone) or has three or more sex chromosomes, not just two (Hamerton & Evans, 2005).

Having an odd number of sex chromosomes impairs cognitive and psychosocial development as well as sexual maturation. The specifics depend on the particular configuration. The only condition in which a person with 45 chromosomes can survive is in the case of a girl with only one X (written as X0, with the 0 standing for no chromosome). This is called Turner syndrome, which results in underdevel- oped female organs and other anomalies.

If there are three sex chromosomes instead of two, a child may seem normal until puberty, particularly if he is a male with Klinefelter syndrome, XXY. Such a boy will be a little slow in elementary school, but not until age 12 or so—when the double X keeps his penis from growing and fat begins to accumulate around his breasts—is it clear that something is wrong. For XXY boys, supplemental hormones can alleviate some physical problems, and special education aids learning—an example of nurture compensating for nature.

Dominant-Gene Disorders Everyone carries genes or alleles that could produce serious diseases or handicaps in the next generation (see Table 3.2). Given that most genes contribute only a small amount to a disorder and that the human genome was just recently mapped, the exact impact of each allele of multifactorial disorders is not yet known (Hinds et al., 2005). However, we do know a great deal about single-gene disorders, since they have been studied for decades.

Most of the 7,000 known single-gene disorders are dominant (always expressed). They are easy to notice: Their dominant effects are apparent in the phenotype. With a few exceptions, severe dominant disorders are rare because people who have such disorders rarely have children and thus the gene dies with them.

One exception is Huntington’s disease, a fatal central nervous system disorder caused by a genetic miscode—this time more than 35 repetitions of a particular triplet. Unlike most dominant traits, the effects of this allele do not begin until middle adulthood. By then a person could have had several children, half of whom would inherit the same dominant gene and therefore would eventually develop Huntington’s disease.

Another disorder, which is probably dominant, is Tourette syndrome. This condi- tion is common because it is not disabling and because its effects vary (Olson, 2004). About 30 percent of those who inherit the syndrome exhibit recurrent, un- controllable tics and explosive verbal outbursts, usually beginning at about age 6. The remaining 70 percent have milder symptoms, such as an occasional twitch that is barely noticeable or a postponable impulse to clear their throat. Many chil- dren and adults without Tourette’s also have such symptoms (Olson, 2004). A per- son with mild Tourette syndrome might curse and tremor when alone but behave normally in public. Girls who have the Tourette genotype often do not express it, at least not with the obvious tics and verbal explosions of young boys. Tourette syndrome is developmental: It often appears at school age, and sometimes disap- pears in adolescence.

Fragile X Syndrome Several genetic disorders are sex-linked, or carried on the X chromosome. Males are thus more likely to be affected by such conditions. One, called fragile X syndrome, is caused by a single gene that has more than 200 repetitions of one

fragile X syndrome A genetic disorder in which part of the X chromosome seems to be attached to the rest of it by a very thin string of molecules. The actual cause is too many repetitions of a particular part of a gene’s code.

Chromosomal and Genetic Abnormalities 81

Especially for Those Worried About Their Sexuality Might you have an undiag- nosed abnormality of your sex chromosome?

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82 CHAPTER 3 ■ Heredity and Environment

Albinism

Alzheimer’s disease

Breast cancer

Cleft palate, cleft lip

Club foot

Cystic fibrosis

Diabetes

Deafness (congenital)

Hemophilia

Hydro- cephalus

Muscular dystrophy (30 diseases)

TABLE 3.2

Common Genetic Diseases and Conditions

Probable Carrier Prenatal Name Description Prognosis Inheritance Incidence* Detection?† Detection?

No melanin; person is very blond and pale

Loss of memory and increasing mental impairment

Tumors in breast that can spread

The two sides of the upper lip or palate are not joined

The foot and ankle are twisted

Mucous obstructions, especially in lungs and digestive organs

Abnormal sugar metabolism because of insufficient insulin

Inability to hear from birth on

Absence of clotting factor in blood

Obstruction causes excess fluid in the brain

Weakening of muscles

Normal, but must avoid sun damage

Eventual death, often after years of dependency

With early treatment, most are cured; without it, death within 3 years

Correctable by surgery

Correctable by surgery

Most live to middle adulthood

Early onset (type 1) fatal without insulin; for later onset (type 2), variable risks

Deaf children can learn sign language and live normally

Death from internal bleeding; blood transfusions prevent damage

Brain damage and death; surgery can make normal life possible

Inability to walk, move; wasting away and sometimes death

Recessive

Early onset— dominant; after age 60— multifactorial

BRCA1 and BRCA2 genes seem dominant; other cases, multifactorial

Multifactorial

Multifactorial

Recessive gene; also spontaneous mutations

Multifactorial; for later onset, body weight is significant

Multifactorial; some forms are recessive

X-linked recessive; also spontaneous mutations

Multifactorial

Recessive or multifactorial

Rare overall; 1 in 8 Hopi Indians is a carrier

Fewer than 1 in 100 middle-aged adults; perhaps 25 percent of all adults over age 85

1 woman in 8 (only 20 percent of breast cancer patients have BRCA1 or BRCA2)

1 in every 700 births; more common in Asian Americans and American Indians

1 in every 200 births; more common in boys

1 in 3,200; 1 in 25 European Americans is a carrier

Type 1: 1 in 500 births; more common in American Indians and African Americans. Type 2: 1 adult in 6 by age 60

1 in 1,000 births; more common in people from Middle East

1 in 10,000 males; royal families of England, Russia, and Germany had it

1 in every 100 births

1 in every 3,500 males develops Duchenne’s

No

Yes, for some genes; ApoE4 allele increases incidence

Yes, for BRCA1 and BRCA2

No

No

Sometimes

No

No

Yes

No

Yes, for some forms

No

No

No

Yes

Yes

Yes, in most cases

No

No

Yes

Yes

Yes, for some forms

*Incidence statistics vary from country to country; those given here are for the United States. All these diseases can occur in any ethnic group. Many affected groups limit transmis- sion through genetic counseling; for example, the incidence of Tay-Sachs disease is declining because many Jewish young adults obtain testing and counseling before marriage. †“Yes” refers to carrier detection. Family history can also reveal genetic risk.

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Chromosomal and Genetic Abnormalities 83

Neural-tube defects (open spine)

Phenylketo- nuria (PKU)

Pyloric stenosis

Rett syndrome

Schizophrenia

Sickle-cell anemia

Tay-Sachs disease

Thalassemia

Tourette syndrome

TABLE 3.2

Probable Carrier Prenatal Name Description Prognosis Inheritance Incidence* Detection?† Detection?

Anencephaly (parts of the brain missing) or spina bifida (lower spine not closed)

Abnormal digestion of protein

Overgrowth of muscle in intestine

Neurological developmental disorder

Severely distorted thought processes

Abnormal blood cells

Enzyme disease

Abnormal blood cells

Uncontrollable tics, body jerking, verbal outbursts

Anencephalic— severe retardation; spina bifida—poor lower body control

Mental retardation, preventable by diet begun by 10 days after birth

Vomiting, loss of weight, eventual death; correctable by surgery

Boys die at birth. At 6–18 months, girls lose communication and motor abilities

No cure; drugs, hospitalization, psychotherapy ease symptoms

Possible painful “crisis”; heart and kidney failure; treatable with drugs

Healthy infant becomes weaker, usually dying by age 5

Paleness and listlessness, low resistance to infections, slow growth

Appears at about age 5; worsens then improves with age

Multifactorial; folic acid deficit and genes

Recessive

Multifactorial

X-linked

Multifactorial

Recessive

Recessive

Usually recessive, occasionally dominant

Dominant, but variable penetrance

Anencephaly—1 in 1,000 births; spina bifida—3 in 1,000; more common in Welsh and Scots

1 in 100 European Americans is a carrier, especially Norwegians and Irish

1 male in 200, 1 female in 1,000; less common in African Americans

1 in 10,000 female births

1 in 100 people develop it by early adulthood

1 in 11 African Americans and 1 in 20 Latinos is a carrier

1 in 30 American Jews and 1 in 20 French Canadians and Old Order Amish are carriers

1 in 10 Americans from southern Europe, northern Africa, or south Asia is a carrier

1 in 250 children

No

Yes

No

No

No

Yes

Yes

Yes

Sometimes

Yes

Yes

No

Sometimes

No

Yes

Yes

Yes

No

Sources: Briley & Sulser, 2001; Butler & Meaney, 2005; Klug & Cummings, 2000; Mange & Mange, 1999; K. L. Moore & Persaud, 2003; Shahin et al., 2002.

Observation Quiz (see answer, page 84): Is there any ethnic group that does not have a genetic condition that is more common among its members than among the general population?

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genetic counseling Consultation and testing by trained experts that enable individuals to learn about their genetic heritage, including harmful conditions that they might pass along to any children they may conceive.

triplet (Plomin et al., 2003). (Some repetitions are normal, but not this many.) The repetitions multiply when that X chromosome is passed from one generation to the next.

Although it is an X-linked, single-gene disorder, fragile X syndrome is not strictly recessive or dominant. About two-thirds of females with the fragile X gene are normal; one-third show some mental deficiency. Of males who inherit a fragile X, about 20 percent seem unaffected, about 33 percent are somewhat retarded, and the rest are severely retarded. Many of those have autistic symptoms as well. If a man with a fragile X is normal, half the sons of his daughters (his grandsons) will probably be significantly impaired because of the increased number of repeti- tions with each generation. But such predictions are approximate as the actual transmission pattern varies.

The cognitive deficits caused by fragile X syndrome are the most common form of inherited mental retardation (many other forms, such as trisomy-21, are not inher- ited) (Sherman, 2002). In addition to having cognitive problems, children with frag- ile X syndrome often are shy, with poor social skills (Hagerman & Hagerman, 2002).

Recessive-Gene Disorders Most recessive disorders are not X-linked. For example, cystic fibrosis, thalassemia, and sickle-cell anemia are all equally common and devastating in males and fe- males (see Table 3.2). About 1 in 12 North Americans is a carrier for one of these three conditions. That high incidence rate results from the fact that although the double recessive pattern is lethal, one recessive gene is protective. For example, carriers of the sickle-cell trait are less likely to die of malaria, which is still a problem in central Africa. Their descendants in North America, including 10 percent of all African Americans, carry a gene that is no longer needed for protection. Cystic fibrosis is most common among people whose ancestors came from northern Europe; carriers may have been protected from cholera.

Sometimes a person who carried a lethal gene has many descendants who marry each other. In that case, the genetic disease becomes common in that group. This happened among Jews in one area of eastern Europe, many of whom inher- ited the recessive Tay-Sachs gene. An infant born with Tay-Sachs disease begins life normally, as a bright, cuddly baby, but then develops slowly and dies before age 5. Many disorders became common because parents of such children tended to have a “replacement” child, who often was a carrier for the same condition. Tay-Sachs also is common among another group with high rates of intermarriage, the French in Louisiana. Probably everyone is a carrier for some recessive disease, but most people do not have children with someone who happens to be a carrier of the same condition.

Genetic Counseling and Testing Until recently, after the birth of a child with a serious or even fatal disorder, cou- ples blamed fate, not genes or chromosomes. Today, many young adults worry about their genes long before they marry. Almost all adults have a relative with a serious disease that is partly genetic, and they want to know the chances of their children inheriting the same disease.

Who Should Get Counseling, and When? Genetic counseling can relieve some of these worries by providing facts and helping prospective parents discuss issues that are relevant to their decisions.

Especially for History Students Some genetic diseases may have changed the course of history. For instance, the last czar of Russia had four healthy daughters and one son with hemophilia. Once called the royal disease, hemophilia is X-linked. How could this rare condition have affected the monarchies of Russia, England, Austria, Germany, and Spain?

84 CHAPTER 3 ■ Heredity and Environment

Response for Those Worried About Their Sexuality (from page 81): That is highly unlikely. Chromosomal abnormalities are evident long before adulthood. It is quite normal for adults to be worried about sexuality for social, not biological, reasons.

➤Answer to Observation Quiz (from page 83): No. As you see, all the major groups are mentioned in Table 3.2. In fact, even much smaller groups whose members tend to marry within the group also have higher rates of particular conditions.

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Counselors must be carefully trained, because many people, especially when con- sidering personal and emotional information, misinterpret words such as “risks” and “probability” (O’Doherty, 2006).

Preconception, prenatal, or even prenuptial genetic testing and counseling are recommended for the following:

■ Individuals who have a parent, sibling, or child with a serious genetic condition ■ Couples who have a history of spontaneous abortions, stillbirths, or infertility ■ Couples from the same ethnic group, particularly if they are relatives ■ Women age 35 or older and men age 40 or older

Genetic counselors try to follow two ethical guidelines. First, the results of their clients’ tests are kept confidential, beyond the reach of insurance com- panies and public records. Second, decisions are made by the clients, not by the counselors. These guidelines are not always easy to follow, as the following illustrates.

Is Knowledge Always Power? Genetic counselors, scientists, and the general public usually favor testing, rea- soning that having some information is better than having none. However, high- risk individuals (who might hear bad news) do not always want to know, especially if the truth might jeopardize their marriage, their insurance coverage, or their chance of parenthood (Duster, 1999).

Chromosomal and Genetic Abnormalities 85

thinking like a scientist Who Decides?

One of the most difficult parts of being a scientist is knowing how to use information so it does not harm others. Consider these cases (adapted from Fackelmann, 1994):

1. A pregnant woman and her husband both have achondro- plastic dwarfism, a dominant condition that affects appear- ance (very short stature, large head) but not intellect. They want genetic analysis of the fetus; they plan to abort if the child would be of normal height.

2. A 40-year-old woman is tested and is told that she has the BRCA1 gene. That means she has about an 80 percent chance of developing breast cancer and is at high risk for ovarian and colon cancer. She does not believe these results and wants no one to tell her mother, her four sisters, or her three daughters, some of whom may be in the early stages of cancer.

3. A 30-year-old mother of two daughters (no sons) is a carrier for hemophilia. She requests IVF and pre-implantation analysis so that only male zygotes without the hemophilia- carrying X chromosome will be implanted. Female zygotes,

all healthy but half of them carriers, would be destroyed, as would the hemophiliac half of her male zygotes.

4. A couple has a child with cystic fibrosis. They want to know if they both carry the recessive gene, in which case they will have no more children, or if the child’s illness was the result of a spontaneous genetic change, as may happen at concep- tion. The test results make it apparent to the counselor that the couple will not have a child with cystic fibrosis, because the husband is not the child’s biological father.

Should test results be kept confidential from other family members who are directly affected (as in examples 2 and 4)? Should a client be given information that will lead to a decision that the counselor believes is unethical (as in examples 1 and 3)? Most counselors answer yes, but many students say that they would break confidentiality for examples 2 and 4 and would refuse to test in examples 1 and 3. As a scientist, you might try to explain information so that others reach your con- clusions, but your job is research, not opinion. What would you do?

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For instance, most people who have a 50/50 risk of developing Huntington’s disease do not want to know their status unless they are contemplating parent- hood. Those who learn that they are not carriers often have a more difficult time coping with the news, psychologically, than their siblings who are carriers (Skirton & Patch, 2002).

It is understandable why people might want to know the risk of conceiving a child with a serious disorder or whether a particular fetus has a disorder, especially if the couple already has had a child with that problem. But an entirely different set of issues is raised by testing after birth.

Sometimes testing is helpful, because knowledge can prevent harm. This is the case for phenylketonuria (PKU), a recessive condition that is more prevalent among northern Europeans than other population groups (Welsh & Pennington, 2000). Newborns with the double recessive genes for PKU will become severely retarded if they consume phenylalanine, a substance found in many foods. If such a baby is immediately started on a diet free of that amino acid, he or she will de- velop normally, or close to it (Hillman, 2005).

In many nations, including the United States, every newborn is tested for PKU. Dozens of other conditions are often tested for (specifics vary by state and nation), sometimes when no treatment is available. Is that ethical? Might bad news make the parents less affectionate toward their baby, making the problem worse? Coun- selors disagree (Twomey, 2006).

Coping with Uncertainty Actually, much is uncertain in genetic testing and counseling. Those who learn that they have a harmful dominant gene, or that they and their partner both carry the same dangerous recessive gene, have new information but also new uncertain- ties. Odds are that half their children will inherit the dominant gene, or that one out of four will have the double recessive, but before actual conception those are merely odds. Some, all, or none of their children could have the disease. Each pregnancy is a new risk, another roll of the same dice.

Further, the interaction of genes and the environment makes development over the life span unpredictable, even if the genes are known. For example, some people with sickle-cell anemia suffer terribly and then die young, while others live satisfy-

86 CHAPTER 3 ■ Heredity and Environment

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There’s Your Baby For many parents, their first glimpse of their future child is an ultra- sound image. This is Alice Morgan, 63 days before birth.

phenylketonuria (PKU) A genetic disorder in which a child’s body is unable to metabolize an amino acid called phenylalanine. Unless phenylalanine is eliminated from the child’s diet, the resulting buildup of that substance in body fluids causes brain damage, pro- gressive mental retardation, and other symptoms.

➤Response for History Students (from page 84): Hemophilia is a painful chronic dis- ease that (before blood transfusions became feasible) killed a boy before adulthood. Though rare, it ran in European royal families, whose members often intermarried, which meant that many queens (including England’s Queen Victoria) were carriers of hemophilia and thus were destined to watch half their sons die of it. All families, even rulers of nations, are distracted from their work when they have a child with a mysterious and lethal illness. Some historians believe that hemo- philia among European royalty was an under- lying cause of the Russian Revolution of 1917 as well as the spread of democracy in the nineteenth and twentieth centuries.

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ing lives, with occasional painful crises that can be weathered. Much depends on the family and social context but also on medical treatments yet to be discovered (Gustafson et al., 2006).

People respond to genetic information in different ways. Some couples at high risk refuse to be tested. Others with the exact same genetic risk are tested and then choose sterilization or adoption. Still others take their chances, either ac- cepting the possibility that they may have a seriously ill child or testing the fetus and aborting it if the double recessive is found.

For many problems, including most recessive genetic disorders and chromosomal abnormalities, a definitive diagnosis can be made after conception but not before. Is a couple willing to start a pregnancy and then end it if the embryo would develop into a seriously ill child? One couple that said no and another that said yes are presented in the next chapter, along with a more general discussion of the methods and problems of prenatal testing.

SUMMING UP

Every person is a carrier for some serious genetic conditions. Most of them are rare, which makes it unlikely that the combination of sperm and ovum will produce severe disabilities. Those recessive diseases that are common occur because carriers survived to reproduce as a result of being protected against some conditions that plagued many of our ancestors.

Often a zygote does not have 46 chromosomes. Such zygotes rarely develop, with two primary exceptions: Down syndrome (trisomy-21) and abnormalities of the sex chromosomes. Genetic counseling helps couples clarify their values and understand the risks before they conceive, but every decision raises ethical questions. Counselors try to explain facts and probabilities, but the final decision is made by those directly involved.

■

Chromosomal and Genetic Abnormalities 87

“The Hardest Decision I Ever Had to Make” That’s how this woman described her deci- sion to terminate her third pregnancy when genetic testing revealed that the fetus had Down syndrome. She soon became pregnant again with a male fetus that had the normal 46 chromosomes, as did her two daughters. Many personal factors influence such deci- sions. Do you think she and her husband would have made the same choice if they had had no other children?RO

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Especially for a Friend A female friend asks you to go with her to the hospital, where she is planning to be surgically sterilized. She says she doesn’t want children, especially since her younger brother recently died of sickle-cell anemia, a recessive disease. What, if anything, should you do?

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88 CHAPTER 3 ■ Heredity and Environment

The Genetic Code 1. Genes are the foundation for all development, first instructing the living creature to form the body and brain, and then regulating behavior. Human conception occurs when two gametes (an ovum and a sperm, each with 23 chromosomes) combine to form a zygote, 46 chromosomes in a single cell.

2. The sex of an embryo depends on the sperm: A Y sperm creates an XY (male) embryo; an X sperm creates an XX (female) embryo. Every cell of every living creature has the unique genetic code of the zygote that began that life. The human genome contains about 25,000 genes in all.

From One Cell to Many 3. Genes interact in various ways, sometimes additively, with each gene contributing to development, and sometimes in a dominant– recessive pattern. Environmental factors influence the phenotype as well.

4. The environment interacts with the genetic instructions for every trait, even for physical appearance. Every aspect of a person is almost always multifactorial and polygenic.

5. Combinations of chromosomes, interactions among genes, and myriad influences from the environment all assure both similarity and diversity within and between species. This aids health and survival.

6. Twins occur if a zygote splits into two separate beings (mono- zygotic, or identical, twins) or if two ova are fertilized by two sperm (dizygotic, or fraternal, twins). Monozygotic multiples are geneti- cally the same. Dizygotic multiples have only half of their genes in common, as do all other siblings who have the same parents.

7. Fertility treatments, including drugs and in vitro fertilization, have led not only to the birth of millions of much-wanted babies but also to an increase in multiple births, which have a higher rate of medical problems.

From Genotype to Phenotype 8. Environmental influences are crucial for almost every complex trait. This includes alcoholism and nearsightedness. Some people are genetically susceptible to each of these, but nongenetic fac- tors affect every condition.

9. Knowing the impact of genes and the environment can be helpful. People are less likely to blame someone for a characteris- tic that is inherited, but realizing that someone is at risk of a seri- ous condition helps with prevention.

Chromosomal and Genetic Abnormalities 10. Often a gamete has fewer or more than 23 chromosomes, creating a zygote with an odd number of chromosomes. Usually such zygotes do not develop. The main exceptions are three chromosomes at the 21st location (Down syndrome, or trisomy- 21) or an odd number of sex chromosomes. In such cases, the child has physical and cognitive problems but can live a nearly normal life.

11. Everyone is a carrier for genetic abnormalities, but usually those conditions are recessive (not affecting their phenotype). If dominant, the trait is usually mild, varied, or inconsequential until late adulthood. If being a carrier for a genetic abnormality, such as the sickle-cell trait, is protective, then that gene can be- come widespread in a population.

12. Genetic testing and counseling can help many couples learn whether their future children are at risk for a chromosomal or genetic abnormality. Genetic testing usually provides information about risks, not actualities. Couples, counselors, and cultures dif- fer in the decisions they make.

DNA (deoxyribonucleic acid) (p. 61)

chromosome (p. 61) gene (p. 61) genome (p. 62) gamete (p. 63) zygote (p. 63) genotype (p. 63) allele (p. 64)

23rd pair (p. 64) XX (p. 64) XY (p. 64) spontaneous abortion (p. 64) induced abortion (p. 64) phenotype (p. 66) polygenic (p. 67) multifactorial (p. 67) Human Genome Project (p. 67)

additive gene (p. 67) dominant–recessive pattern

(p. 68) X-linked (p. 68) monozygotic (MZ) twins (p. 69) dizygotic (DZ) twins (p. 70) clone (p. 70) in vitro fertilization (IVF) (p. 71) infertility (p. 71)

assisted reproductive technology (ART) (p. 71)

carrier (p. 73) type 2 diabetes (p. 77) mosaic (p. 79) Down syndrome (p. 79) fragile X syndrome (p. 81) genetic counseling (p. 84) phenylketonuria (PKU) (p. 86)

SUMMARY

KEY TERMS

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Summary 89

6. What are the differences among monozygotic twins, dizygotic twins, other siblings, and clones?

7. From the prospective parents’ perspective, what are the advan- tages and disadvantages of adoption versus ART?

8. Explain how the course of alcoholism or nearsightedness is affected by nature and by nurture.

9. What are the causes and effects of Down syndrome?

10. Why is genetic counseling a personal decision and usually confidential?

11. Genetic testing for various diseases is much more common than it once was. What are the advantages and disadvantages?

1. What are the relationships among proteins, genes, chromo- somes, and the genome?

2. How and when is the sex of a zygote determined? Why is the ratio of boy babies to girl babies significant?

3. Which method of identifying a criminal do you think is most accurate: a lineup of suspects, a confession, a fingerprint match, DNA identification? Why?

4. Genetically speaking, how similar are people to one another and to other animals?

5. Sometimes parents have a child who looks like neither of them. How does that happen?

3. Draw a genetic chart of your biological relatives, going back as many generations as you can, listing all serious illnesses and causes of death. Include ancestors who died in infancy. Do you see any genetic susceptibility? If so, how can you overcome it?

4. List a dozen people you know who need glasses (or other cor- rective lenses) and a dozen who do not. Are there any patterns? Is this correlation or causation?

1. Pick one of your traits, and explain the influences that both nature and nurture have on it. For example, if you have a short temper, explain its origins in your genetics, your culture, and your childhood experiences.

2. Many adults have a preference for a son or a daughter. Interview adults of several ages and backgrounds about their preferences. If they give the socially preferable answer (“It does not matter”), ask how they think the two sexes differ. Listen and take notes—don’t debate. Analyze the implications of the responses you get.

KEY QUESTIONS

APPLICATIONS

➤Response for a Friend (from page 87): She needs the information you have. She may not be a carrier of the sickle-cell trait (you know she doesn’t have the disease, so she has one chance in three of not being a carrier). Even if she is a carrier, she can have a child with the disease only if the father of her child is also a carrier—and then there is only one chance in four. Urge your friend not to do anything irreversible.

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Prenatal Development and Birth

Wonder and worry, worry and wonder. Boy or girl? One baby ortwo? What color hair, eyes, and skin? What shape head, nose,and chin? When, how, and where will birth occur? Will thebaby be healthy, well formed, ready for life? My friend Judy, who taught history at the United Nations School, habitu-

ally contrasted the broad sweep of global history and the immediate, local particulars. She did this even when she was pregnant: She rubbed her belly and said, “Statistically, this is probably a Chinese boy.”

Judy was right. The majority of newborns are male (about 52 percent), and more of them are Chinese than any other ethnicity (about 25 percent). Given Judy’s personal particulars, though, no one was surprised when she gave birth to a European American girl. Judy herself seemed awestruck, repeatedly recounting tiny details, as if no baby like hers had ever appeared before. She was right about that, too.

This anecdote illustrates the dual themes of this chapter. Every topic— prenatal development, possible toxins, birthweight, medical assistance, bonding, and so on—is directly relevant to the 150 million babies born in the world every year. Yet each pregnancy and every birth is unique. This chapter includes both generalities and variations. Learn all you can, and then, if you have a baby, expect to be awed by your personal miracle.

From Zygote to Newborn The most dramatic and extensive transformation of the entire life span occurs before birth. To make it easier to study, the awesome process of prenatal development is often divided into three main periods. The first two weeks are called the germinal period; the weeks from the third through the eighth are the embryonic period; the months from the ninth week until birth are the fetal period. (Alternative terms are discussed in Table 4.1.)

Germinal: The First 14 Days You learned in Chapter 3 that the one-celled zygote soon begins to duplicate, divide, and differentiate (see Figure 4.1). When the cells take on distinct characteristics and gravitate toward particular positions, the entire cell mass—still very fragile and tiny—is called a blastocyst.

4

91

CHAPTER OUTLINE

� From Zygote to Newborn

Germinal: The First 14 Days Embryo: From the Third Through

the Eighth Week Fetus: From the Ninth Week Until Birth

� Risk Reduction

Determining Risk Protective Measures THINKING LIKE A SCIENTIST:

On Punishing Pregnant Drinkers Benefits of Prenatal Care A CASE TO STUDY: “What Do People

Live to Do?” A CASE TO STUDY: “What Did That

Say About Me?”

� The Birth Process

The Newborn’s First Minutes Variations Birth Complications Social Support A CASE TO STUDY: “You’d Throw

Him in a Dumpster” Postpartum Depression

germinal period The first two weeks of pre- natal development after conception, characterized by rapid cell division and the beginning of cell differentiation.

embryonic period The stage of prenatal development from approximately the third through the eighth week after conception, during which the basic forms of all body structures, including internal organs, develop.

fetal period The stage of prenatal develop- ment from the ninth week after conception until birth, during which the organs grow in size and mature in functioning.

blastocyst A cell mass that develops from the zygote in the first few days after con- ception, during the germinal period, and forms a hollow sphere in preparation for implantation.

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About a week after conception, the blastocyst, now consisting of more than 100 cells, separates into two distinct masses. The outer cells form a shell that will be- come the placenta (the organ that develops within the mother’s uterus to protect and nourish the developing creature), and the inner cells form the nucleus of what will next become the embryo.

The first task of the outer cells is to achieve implantation—that is, to embed themselves in the nurturing environment of the uterus. Implantation occurs about 10 days after conception and is hazardous (K. L. Moore & Persaud, 2003). At least 60 percent of all natural conceptions and 70 percent of all in vitro conceptions fail to implant (see Table 4.2).

placenta The organ that surrounds the devel- oping embryo and fetus, sustaining life via the umbilical cord. The placenta is attached to the wall of the uterus.

implantation The process, beginning about 10 days after conception, in which the developing organism burrows into the pla- centa that lines the uterus, where it can be nourished and protected as it continues to develop.

92 CHAPTER 4 ■ Prenatal Development and Birth

Two-celled stage

Ova

Zygote (single cell) Conception

Fallopian tube

Implantation

Sperm

Ovary

Ovum FIGURE 4.1

The Most Dangerous Journey In the first 10 days after conception, the organism does not increase in size because it is not yet nour- ished by the mother. However, the number of cells increases rapidly as the organism pre- pares for implantation, which occurs success- fully about a third of the time.

TABLE 4.1

Timing and Terminology

Popular and professional books use various phrases to segment pregnancy. The following comments may help to clarify the phrases used.

■ Beginning of pregnancy: Pregnancy begins at conception, which is also the starting point of gestational age. However, the organism does not become an embryo until about two weeks later, and pregnancy does not affect the woman (and cannot be confirmed by blood or urine testing) until implantation. Paradoxically, many obstetricians date the onset of pregnancy from the date of the woman’s last menstrual period (LMP), about 14 days before conception.

■ Length of pregnancy: Full-term pregnancies last 266 days, or 38 weeks, or 9 months. If the LMP is used as the starting time, pregnancy lasts 40 weeks, sometimes expressed as 10 lunar months. (A lunar month is 28 days long.)

■ Trimesters: Instead of germinal period, embryonic period, and fetal period, some writers divide pregnancy into three-month periods called trimesters. Months 1, 2, and 3 are called the first trimester; months 4, 5, and 6, the second trimester; and months 7, 8, and 9, the third trimester.

■ Due date: Although doctors assign a specific due date (based on the woman’s LMP), only 5 percent of babies are born on that exact date. Babies born between three weeks before and two weeks after that date are considered “full term” or “on time.” Babies born earlier are called preterm; babies born later are called post-term. The words preterm and post- term are more accurate than premature and postmature.

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Embryo: From the Third Through the Eighth Week The start of the third week initiates the embryonic period, when the former blasto- cyst becomes a distinct being—not yet recognizably human but worthy of a new name, embryo. The first sign of a human body structure appears as a thin line (called the primitive streak) down the middle of the embryo. This line becomes the neural tube 22 days after conception, eventually developing into the central nervous system—the brain and spinal cord (K. L. Moore & Persaud, 2003).

The head begins to take shape in the fourth week, as eyes, ears, nose, and mouth form. Also in the fourth week, a minuscule blood vessel that will become the heart begins to pulsate, making the cardiovascular system the first to show any activity.

By the fifth week, buds that will become arms and legs appear. The upper arms and then forearms, palms, and webbed fingers form. Legs, feet, and webbed toes, in that order, emerge a few days later, each with the beginning of a skeletal struc- ture. Then—52 and 54 days after conception, respectively—the fingers and toes separate.

embryo The name for a developing organism from about the third through the eighth week after conception.

From Zygote to Newborn 93

TABLE 4.2

Vulnerability During Prenatal Development

The Germinal Period At least 60 percent of all developing organisms fail to grow or implant properly and thus do not survive the germinal period. Most of these organisms are grossly abnormal.

The Embryonic Period About 20 percent of all embryos are aborted spontaneously, most often because of chromosomal abnormalities.

The Fetal Period About 5 percent of all fetuses are aborted spontaneously before viability at 22 weeks or are stillborn, defined as born dead after 22 weeks.

Birth About 31 percent of all zygotes grow and survive to become living newborn babies.

Sources: Bentley & Mascie-Taylor, 2000; K. L. Moore & Persaud, 2003.

First Stages of the Germinal Period The original zygote as it divides into (a) two cells, (b) four cells, and (c) eight cells. Occasionally at this early stage, the cells separate completely, forming the beginning of monozygotic twins, quadruplets, or octuplets.

(a) (b) (c)

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At the eighth week after conception (56 days), the embryo weighs just one- thirtieth of an ounce (1 gram) and is about 1 inch (21⁄2 centimeters) long. The head has become rounded, and the features of the face are formed. The embryo has all the basic organs and body parts of a human being, including elbows and knees, nostrils and toes, and a unisex structure called the indifferent gonad. It moves frequently, about 150 times an hour (Piontelli, 2002).

Fetus: From the Ninth Week Until Birth The developing organism is called a fetus from the ninth week after conception until birth. During the fetal period, it develops from a tiny, sexless creature smaller than the last joint of your thumb to a 71⁄2-pound, 20-inch (3,400 grams, 51 cen- timeters) boy or girl.

The Third Month If an embryo is male (XY), the SRY gene on the Y chromosome commands that male sexual organs develop; with no such command, the indifferent gonad devel- ops into female sex organs. By the 12th week, the genitals are fully formed and are sending hormones to the developing brain. Although most functions of the brain are gender-neutral, hormones cause some sex differences in brain organization by mid-pregnancy (Cameron, 2001).

At the end of the third month, the fetus has all its body parts, weighs approxi- mately 3 ounces (87 grams), and is about 3 inches (7.5 centimeters) long. Early prenatal growth is very rapid, but there is considerable variation from fetus to fetus, especially in body weight (K. L. Moore & Persaud, 2003). The numbers just given —3 months, 3 ounces, 3 inches—are rounded off for easy recollection. (For those on the metric system, “100 days, 100 millimeters, 100 grams” is similarly useful.)

Despite the variations, some aspects of third-month growth are universal. The fetus is too small to survive outside the womb, the organs are not yet functioning, but all the body structures are in place.

94 CHAPTER 4 ■ Prenatal Development and Birth

fetus The name for a developing organism from the ninth week after conception until birth.

The Embryonic Period (a) At 4 weeks past conception, the embryo is only about 1⁄8 inch (3 millimeters) long, but already the head (top right) has taken shape. (b) At 5 weeks past conception, the embryo has grown to twice the size it was at 4 weeks. Its primitive heart, which has been puls- ing for a week now, is visible, as is what appears to be a primitive tail,

which will soon be enclosed by skin and protective tissue at the tip of the backbone (the coccyx). (c) By 7 weeks, the organism is somewhat less than an inch (21⁄2 centimeters) long. Eyes, nose, the digestive system, and even the first stage of toe formation can be seen. (d) At 8 weeks, the 1-inch-long organism is clearly recognizable as a human fetus.

(a) (b) (c) (d)

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Especially for Feminists Many people believe that the differences between the sexes are primarily sociocultural, not biological. Is there any prenatal support for that view?

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The Middle Three Months: Preparing to Survive In the fourth, fifth, and sixth months, the heartbeat becomes stronger and the cardiovascular system becomes more active. Digestive and excretory systems develop. Fingernails, toenails, and buds for teeth form, and hair grows (includ- ing eyelashes).

Amazing as body growth is, the brain is even more impressive, increasing about six times in size and developing many new neurons, or brain cells (in a process called neurogenesis), and syn- apses (synaptogenesis), which are con- nections between neurons. The neurons begin to organize themselves, some dying, some extending long axons to distant neurons (Kolb & Whishaw, 2003). Brain growth and neurological organization continue for years, as you will see in later chapters (in which neu- rons, synapses, and axons are explained more fully), but the entire central nervous system first emerges during mid-pregnancy.

Advances in fetal brain functioning are critical to attainment of the age of via- bility, the age at which a preterm newborn can survive. That’s because the brain regulates basic body functions, such as breathing and sucking. With advanced medical care, the age of viability is about 22 weeks after conception, although most such babies weigh under 500 grams (less than a pound). (For a summary of information about preterm birthweights, see Table 4.7 on page 113.)

Babies born before 22 weeks of gestation do not survive. This 22-week barrier has not been reduced by even the most sophisticated respirators and heart regula- tors, probably because maintaining life requires some brain response (Paul et al., 2006). At 23–26 weeks, the survival rate improves to up to two-thirds (Kelly, 2006; Wilson-Costello et al., 2007).

However, these newborns are vulnerable. A study that compared 8-year-olds who had been born very early with others who had been born “full term” (at 35–40 weeks) found that 20 percent of the preterm children had cerebral palsy, 41 percent had some mental retardation, and only 20 percent had no disabilities (Marlow et al., 2005). Although fewer 22- to 28-week- old newborns were stillborn in the past decade, their mortality and morbidity have not improved, leading one team to suggest that neonatal care has reached its limits (Paul et al., 2006).

At about 28 weeks, brain-wave patterns include occasional bursts of activity that resemble the sleep–wake cycles of a newborn (Joseph, 2000), and heart rate and body movement become reac- tive, not random, decreasing when the fetus needs rest. Because of brain maturation, most babies born at 28 weeks develop normally.

Weight is also significant. By 28 weeks, the typical fetus weighs about 3 pounds (1.3 kilograms), and its chances of survival are 95 percent.

Maturity is more crucial than birthweight. Even very tiny babies sometimes live if they are a few weeks past the age of viability.

From Zygote to Newborn 95

The Fetus At the end of 4 months, the fetus, now 6 inches long, looks fully formed but out of proportion—the distance from the top of the skull to the neck is almost as long as that from the neck to the rump. For many more weeks, the fetus must depend on the translucent membranes of the placenta and umbilical cord (the long white object in the foreground) for survival.

Observation Quiz (see answer, page 96): Can you see eyebrows, fingernails, and genitals?

Can He Hear? A fetus, just about at the age of viability, is shown fingering his ear. Such gestures are probably random; but, yes, he can hear.

age of viability The age (about 22 weeks after conception) at which a fetus might survive outside the mother’s uterus if specialized medical care is available.

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Rumaisa Rahman was born after 25 weeks and 6 days weighing only 8.6 ounces (244 grams). Rumaisa had four advantages besides her ges- tational maturity: her sex (boys are more likely to die); her birthplace (Chicago’s Loyola University Hospital, which specializes in preterm ba- bies); her birth process (cesarean delivery is easier on the fetus); and the reason she was so tiny (she was a twin) (CBS News, 2005).

Another very tiny preterm infant has bucked the odds and survived. Amillia Taylor was born in October 2006 after only 21 weeks and six days in the uterus—a new record. Since she was conceived via IVF, she was actually 22 weeks old at birth, weighing just 10 ounces (284 grams) and measuring a mere 91⁄2 inches. As with Rumaisa, her survival was aided by her sex and place of birth, a specialized neonatal facility within Baptist Children’s Hospital of Miami, Florida (Wingert, 2007).

The Final Three Months: From Viability to Full Term Attaining viability simply means that life outside the womb is possible. Each day of the final three months of prenatal growth improves the odds not merely of survival but of a healthy and happy baby.

A viable preterm infant born in the seventh month is a tiny creature requiring intensive hospital care and life-support systems for each gram of nourishment and for every shallow breath. By contrast, after nine months or so, the typical full-term infant is a vigorous person, ready to thrive at home on mother’s milk—no expert help, oxygenated air, or special feeding required.

The critical difference between a fragile preterm baby and a robust newborn is maturation of the neurological, respiratory, and cardiovascular systems. In the last three months of prenatal life, brain waves indicate responsiveness; the lungs ex- pand and contract using the amniotic fluid as a substitute for air; and heart valves, arteries, and veins circulate the fetal blood.

Weight gain in the last three months is about 41⁄2 pounds (2,000 grams). This ensures adequate nutrition to the rapidly developing brain and thus avoids severe malnutrition in the second half of pregnancy, which would reduce the baby’s abil- ity to learn (Georgieff & Rao, 2001). At full term, human brain growth is so exten- sive that the cortex (the brain’s advanced outer layer) forms several folds in order to fit into the skull (see Figure 4.2).

The relationship between mother and child intensifies during the final three months, for fetal size and movements make the pregnant woman very aware of it. In turn, the fetus becomes aware of her sounds (voice and heartbeat), smells (via amniotic fluid), and behavior (Aslin & Hunt, 2001). Regular walking is soothing, and sudden noises cause the fetus to jump. When the mother is highly fearful or anxious, the fetal heart beats faster and body movements increase (DiPietro et al., 2002).

SUMMING UP

In two weeks of rapid cell duplication, differentiation, and finally implantation, the one- celled zygote becomes a blastocyst and then a many-celled embryo. The embryo devel- ops the beginning of the central nervous system (3 weeks), a heart and a face (4 weeks), arms and legs (5 weeks), hands and feet (6 weeks), and fingers and toes (7 weeks), while the inner organs take shape. By 8 weeks, all the body structures, except male and female organs, are in place. Fetal development proceeds rapidly, with weight gain (about 2 pounds, or 900 grams) and brain maturation, which make viability possible by about 22 weeks. Further development of the brain, lungs, and heart make the full-term, 35- to 40-week-old newborn ready for life.

■

96 CHAPTER 4 ■ Prenatal Development and Birth

The World’s Littlest Baby For reasons dis- cussed in the text, tiny Rumaisa Rahmon has a good chance of living a full, normal life. Rumaisa gained 5 pounds (2,270 grams) in the hospital and then, 6 months after her birth, went home. Her twin sister, Hiba, who weighed 1.3 pounds (600 grams) at birth, had gone home two months earlier. At their one- year birthday, the twins seemed normal, with Rumaisa weighing 15 pounds (6,800 grams) and Hiba 17 (7,711 grams) (CBS News, 2005).

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➤Answer to Observation Quiz (from page 95): Yes, yes, and no. Genitals are formed, but they are not visible in this photo. The object growing from the lower belly is the umbilical cord.

➤Response for Feminists (from page 94): Only one of the 46 human chromosomes determines sex, and the genitals develop last in the prenatal sequence. Sex differences are apparent before birth, but they are relatively minor.

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Risk Reduction Many toxins, illnesses, and experiences can harm a developing person before birth. If this topic alarms you, bear in mind that the large majority of newborns are healthy and capable. Only about 3 percent have major structural anomalies, such as cleft palate, malformed organs, or missing limbs (K. L. Moore & Persaud, 2003), and another 10 percent have minor physical problems that modern medicine can treat, such as an extra digit or an undescended testicle.

Prenatal development should be thought of not as a dangerous period to be feared but as a natural process to be protected. The goal of teratology, the study of birth defects, is to increase the odds that every newborn will have a healthy start. Teratogens are substances (such as drugs and pollutants) and conditions (such as severe malnutrition and extreme stress) that increase the risk of prenatal abnormalities.

Teratogens cause not only physical problems but also impaired learning and be- havior. Teratogens that harm the brain, making a child hyperactive, antisocial, learning-disabled, and so on, are called behavioral teratogens. The origins of

Risk Reduction 97

teratogens Agents and conditions, including viruses, drugs, and chemicals, that can impair prenatal development and result in birth defects or even death.

behavioral teratogens Agents and conditions that can harm the prenatal brain, impairing the future child’s intellectual and emotional functioning.

Brain stem

Forebrain

Hindbrain

Midbrain

(a) 25 days (b) 50 days (c) 100 days

(d) 20 weeks (e) 28 weeks

(f) 36 weeks (full term)

Source: Adapted from Cowan, 1997, p. 116.

Neural tube (forms spinal cord)

FIGURE 4.2

Prenatal Growth of the Brain Just 25 days after conception (a), the central nervous system is already evident. The brain looks distinctly human by day 100 (c). By the 28th week of gestation (e), at the very time brain activity begins, the various sections of the brain are recognizable. When the fetus is full term (f), all the parts of the brain, including the cortex (the outer layer), are formed, folding over one another and becoming more convoluted, or wrinkled, as the number of brain cells increases.

Especially for the Friend of a Pregnant Woman Suppose that your friend is frightened of having an abnormal child. She refuses to read about prenatal development because she is afraid to learn about what could go wrong. What could you tell her?

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such problems are difficult to trace, but about 20 percent of all children have be- havioral difficulties (usually not noticed until years after birth) that could be con- nected to damage done during the prenatal period.

Determining Risk It was once believed that the placenta screened out all harmful substances. Then two tragedies occurred. Doctors on an Australian military base traced an increase in blindness among newborns to rubella (German measles) contracted by preg- nant women a few months earlier (Gregg, 1941, in Persaud et al., 1985); a sudden increase in European infants born with missing or deformed arms and legs in the late 1950s was traced to a new drug called thalidomide (Schardein, 1976). It be- came obvious that scientists needed to know how this happened, and teratology began.

Teratology is a science of risk analysis, of weighing the chances that a particu- lar teratogen (substance or condition that could cause harm) will affect the fetus. Understanding risk is crucial for understanding human development; every period of life entails certain risks, and much harm can be avoided.

All teratogens increase risk, but none always cause damage. Several influential prenatal factors—timing, dosage, and genes—are described here. Other, postnatal influences—such as early care and attachment—are discussed in the three chap- ters on infancy (5, 6, and 7). Still others—education, friendship, vocation—are discussed later in this text.

Timing of Exposure One crucial factor is timing—the age of the developing organism when it is ex- posed to the teratogen. Some teratogens cause damage early in prenatal develop- ment, when a particular part of the body is forming. Thalidomide, for example, stopped the formation of arms and legs in weeks 6 or 7 but caused no damage after week 9.

The time of greatest susceptibility is called the critical period. As you can see in Figure 4.3, each body structure has its own critical period. The entire six weeks of the embryonic stage can be called a critical period for physical structure and form, with the specifics varying somewhat week by week (K. L. Moore & Persaud, 2003).

Because the early days are critical, most obstetricians today recommend that before pregnancy, all couples get counseling, stop using recreational drugs (espe- cially alcohol), and update their immunizations (Kuller et al., 2001). In addition, a prospective mother should make sure her body is ready by supplementing a bal- anced diet with extra folic acid and iron. Not all women follow these recommen- dations (see Table 4.3).

Since the brain continues to grow throughout prenatal development, there is no safe period for behavioral teratogens. Teratogens that cause preterm birth or low birthweight (notably cigarettes) are particularly harmful in the second half of preg- nancy, but, for many reasons, women should stop smoking or ingesting any drugs, and start eating well and taking prenatal vitamins, before conceiving.

Amount of Exposure A second important factor is the dose and/or frequency of exposure. Some teratogens have a threshold effect; that is, they are virtually harmless until exposure reaches a certain level, at which point they “cross the threshold” and become damaging (Reece & Hobbins, 2007). Indeed, a few substances are beneficial in small amounts

risk analysis The science of weighing the potential effects of a particular event, sub- stance, or experience to determine the likelihood of harm. In teratology, risk analy- sis attempts to evaluate everything that affects the chances that a particular agent or condition will cause damage to an embryo or fetus.

critical period In prenatal development, the time when a particular organ or other body part of the embryo or fetus is most sus- ceptible to damage by teratogens.

threshold effect A situation in which a certain teratogen is relatively harmless in small doses but becomes harmful once exposure reaches a certain level (the threshold).

98 CHAPTER 4 ■ Prenatal Development and Birth

➤Response for the Friend of a Pregnant Woman (from page 97): Reassure her that almost all pregnancies turn out fine, partly because most defective fetuses are spontane- ously aborted (miscarried) and partly because protective factors are active throughout pregnancy. Equally important, the more she learns about teratogens, the more she will learn about protecting her fetus. Many birth defects and complications can be prevented with good prenatal care.

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but fiercely teratogenic in large quantities. For example, vitamin A is an essential part of the prenatal diet, but more than 10,000 units per day may be too much and 50,000 units can cause abnormalities in body structures.

For most teratogens, experts hesitate to specify a safe threshold. One reason is the interaction effect, when one teratogen intensifies the impact of another. Alcohol, tobacco, and marijuana interact, doing more harm in combination than any one of them does alone. Ironically, using any one of these three makes a preg- nant woman likely to use the others as well.

Genetic Vulnerability A third factor that determines whether a specific teratogen will be harmful, and to what extent, is the developing organism’s genes (Mann & Andrews, 2007). Although

Especially for Nutritionists Is it beneficial that most breakfast cereals are fortified with vitamins and minerals?

Risk Reduction 99

interaction effect The result of a combination of teratogens. Sometimes risk is greatly magnified when an embryo or fetus is exposed to more than one teratogen at the same time.

3 2 1 4 5 6 7 8 9 16 32 38

Fetal Period (in weeks) Main Embryonic Period (in weeks) Germinal Period

Major congenital anomaliesTeratogens often prevent implantation

Source: Adapted from K. L. Moore & Persaud, 2003.

Palate

Sex organs Masculinization of female genitalia

Functional defects and minor anomalies

Cleft palate

Enamel staining

Cataracts, glaucoma

Low-set malformed ears and deafness

Cleft lip

Heart

Arms

Legs

Lips

Ears

Eyes

Teeth

Birth Defects from Teratogens: Time of Exposure and Effect on Major Organs

Neural-tube defects Mental retardation Learning disabilities

Common site(s) of action of teratogens

Less critical period

Highly critical period

Central nervous system

CNS CNS CNS

CNS Ear Ear

Eye

Eye

Eye Eye Heart

Heart

Heart Sex organs

Arm

Arm

Leg

FIGURE 4.3

Critical Periods in Human Development The most serious damage from teratogens (orange bars) is likely to occur early in prenatal development. However, significant damage (purple bars) to many vital parts of the body, including the brain, eyes, and genitals, can occur during the last months of pregnancy as well.

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precise genetic research has not yet connected fetal genes and teratogens, it is ap- parent that dizygotic twins, exposed to the same teratogens, experience different effects. Cleft lip, cleft palate, and club foot almost certainly result from a combi- nation of genetic vulnerability, stress, and inadequate nutrition (Botto et al., 2004; Hartl & Jones, 1999).

International comparisons of rates of birth defects also suggest that genes are a factor (World Health Organization, 2003). For example, Japan has relatively low rates of many birth defects, but its rate of newborns with cleft lip is three times that of Canada. The fact that nations, and even regions within nations, have high rates of some defects and low rates of others suggests genetic vulnerabilities and protections.

Genes are known to affect the likelihood of neural-tube defects (see Table 3.2, pp. 82–83). Both spina bifida and microcephaly are more common in some ethnic groups (specifically, among infants of Irish, English, and Egyptian descent) and less common in others (most Asian and African groups), because some groups have more carriers of an allele that decreases the normal utilization of folic acid (Mills et al., 1995). Knowing this led to a solution: If every pregnant woman con- sumed extra folic acid, the embryos with this allele would still get enough of this B vitamin to develop a normal nervous system.

Since the genes of the fetus are unknown, and the central nervous system be- gins to form in the third week after conception, women are urged to take vitamins with folic acid before becoming pregnant. Only a third of U.S. women take extra folic acid before conception (Suellentrop et al., 2006). However, thanks to a 1996 U.S. law and a 1998 Canadian one, cereal and bread manufactured in those coun- tries are now fortified with folic acid. As a result, folic acid consumption in the United States has increased by 50 percent (Bentley et al., 2006), and neural-tube defects have decreased by 26 percent (MMWR, September 13, 2002). In Europe, where no food fortification has occurred, neural-tube defects have not decreased (Botto et al., 2005).

100 CHAPTER 4 ■ Prenatal Development and Birth

TABLE 4.3

Before You Become Pregnant

What Prospective Mothers Should Do What Prospective Mothers Really Do (U. S. data) 1. Take a daily multivitamin with folic acid.

2. Avoid binge drinking (defined as 4 or more drinks in a row).

3. Update immunizations against all teratogenic viruses, especially rubella.

4. Gain or lose weight, as appropriate.

5. Reassess your use of prescription drugs.

6. Know status regarding sexually transmitted diseases.

1. In 2004, 40 percent of women aged 18 to 45 did so, up from 30 percent in previous years.

2. One-eighth of all women who might become pregnant (are sexually active, use no contraception) binge-drink (55 percent of binge drinkers are alcoholics).

3. Because of laws regarding school admission, most young women in the United States are well immunized.

4. Babies born to underweight women are at risk for low birthweight. Babies born to obese women have three times the usual rate of birth complications.

5. Eighty-five percent of pregnant women are taking prescription drugs (not counting vitamins).

6. Only a third of sexually active women get tested for the most common STD, chlamydia. Even fewer are screened for other, more dangerous infections, such as syphilis and HIV.

Sources: Andrade et al., 2004; Cedergren, 2004; MMWR, September 17, 2004; MMWR, October 29, 2004; MMWR, December 24, 2004.

➤Response for Nutritionists (from page 99): Useful, yes; optimal, no. Some essential vitamins are missing (too expensive), and individual needs differ, depending on age, sex, health, genes, and eating habits. The reduction in neural-tube defects is good, but many women do not benefit because they don’t eat cereal or take vitamin supplements before becoming pregnant.

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In some cases, genetic vulnerability is related to the sex of the developing or- ganism. Generally, males (XY) are at greater risk. That is one explanation for the more frequent spontaneous abortions of male than female fetuses. In addition, boys have more birth defects, learning disabilities, and other problems caused by behavioral teratogens.

Protective Measures Because of the many variables involved, the results of teratogenic exposure cannot be predicted in individual cases. However, much is known about common and damaging teratogens and about how individuals and society can reduce the risks. Table 4.4, on pages 103–104, lists some teratogens and their effects, as well as preventive measures.

Some pregnant women are exposed to these teratogens with no evident harm, and some defects occur for reasons unknown. Women are advised to avoid all drugs, chemicals in pesticides (including bug spray), construction materials (in- cluding solvents), and cosmetics (including hair dye) before becoming pregnant.

Such advice is easy to give but not easy to follow. Even doctors should be more careful. A study (see Research Design) of 152,000 births in eight U.S. health main- tenance organizations (HMOs) found that doctors wrote an average of three pre- scriptions per pregnant woman, including many for drugs not declared safe during pregnancy (prescribed for 38 percent) and some for drugs with proven risks to human fetuses (prescribed for 5 percent). Some of those drugs with proven risks (3.4 percent) were in the Food and Drug Administration’s category D, meaning that even though they have been proven to be sometimes harmful, they may be worth the risk for the sake of the mother’s health. A few (1 percent) were in category X, meaning that they should never be taken because they are proven teratogens and alternatives are available (Andrade et al., 2004).

How could this happen? Perhaps the doctors did not know that their patients were pregnant (the women had already had their first prenatal visit, but they might not have told the prescribing doctor), or perhaps the women did not take the drugs. But women are not always cautious: A nationwide survey has found that some women acknowledge smoking (14 percent) and drinking (5 percent) during the last 3 months of their pregnancies (Suellentrop et al., 2006).

In the past few decades, scientists have identified hundreds of teratogens that might harm an embryo or fetus. Almost every common disease, almost every food additive, most prescription and nonprescription drugs (even caffeine and aspirin), trace minerals in the air and water, emotional stress, exhaustion, and even hunger are suspected of impairing prenatal development. Why have scientists not acted on this information, perhaps by calling on the authorities to take away the license of any doctor who prescribed any drug to a pregnant woman or to arrest any woman who smoked or drank?

Remember the scientific method. A hypothesis is tested in many ways, conclu- sions are tentatively drawn, and researchers note limitations and examine alterna- tive explanations. Most research on teratogens has been done with mice; harm to humans is rarely proven to the satisfaction of every scientist. Definitive proof may take decades, and scientists are taught to be careful.

What would it take for scientists to agree that a substance was a teratogen for humans? A substance would need to be given to hundreds, perhaps thousands, of pregnant women, at various times in the pregnancy (early, late, throughout), with no confounding influences (the women would need to be similar in genes, nutri- tion, health, medical care). Then their offspring would have to be examined not

Risk Reduction 101

Research Design Scientists: Susan Andrade and others.

Publication: American Journal of Obstetrics and Gynecology (2004).

Participants: 152,531 women who gave birth from 1996 to 2000.

Design: Computer search of records from eight HMOs for prescriptions written for these participants between the date of the first prenatal visit and the delivery date.

Major conclusion: Many doctors pre- scribe drugs for pregnant women that are not known to be safe.

Comment:This method avoids the pos- sibility of women or doctors forgetting or denying drug use during pregnancy. However, some of the women may not have taken the drugs that were pre- scribed for them, either by their own choice or on advice from a physician. Follow-up research is needed to estab- lish a correlation between birth defects and drugs prescribed.

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102 CHAPTER 4 ■ Prenatal Development and Birth

thinking like a scientist On Punishing Pregnant Drinkers

Alcohol in high doses is a proven teratogen. Proof did not come easy; 40 years ago drinking alcohol during pregnancy was be- lieved to be harmless. But some obstetricians noted that a few patients who drank heavily had babies with distorted facial fea- tures, including small eyes and a thin upper lip. As those chil- dren grew, they turned out to be mentally retarded, impulsive, and hyperactive. This combination was given the name fetal al- cohol syndrome (FAS).

The diagnosis of FAS was possible because alcohol was widely used. That meant that, once suspicions were raised, the correlation between excessive maternal drinking and fetal harm became “obvious.” This hypothesis was tested with thousands of mice and monkeys and with alcoholic women throughout the world, including, recently, in South Africa (May et al., 2005). Replication over the decades has convinced all scientists.

However, not every pregnant woman who drinks heavily has a newborn with FAS. Might the risk of being born with FAS be dose-related or genetic? If FAS is not visibly present, might the infant become hyperactive or a slow learner? Surveys and longi- tudinal studies have confirmed a correlation between drinking by a pregnant woman and damage to the fetus (Streissguth & Connor, 2001).

Not all scientists are convinced. Some infants born to drink- ing mothers seem unharmed, and many pregnant drinkers have other problems: drug abuse; unstable eating and sleeping pat- terns; bouts of anxiety, stress, or depression; accidental injuries; domestic violence; sexual infections; malnutrition; illnesses; lack of family support; and inadequate medical care. Any of these can lead to hyperactivity and slower learning in a child, whether the mother drinks or not. Some scientists (especially in Europe) wonder whether occasional, moderate drinking during pregnancy might be acceptable. They note that moderate drink- ing aids human longevity (Smith & Hart, 2002).

Nevertheless, most doctors in the United States advise preg- nant women to abstain completely from alcohol. Moreover, since 1998, four states have authorized “involuntary commit- ment” ( jail or forced residential treatment) for pregnant women who do not stop drinking (National Institute on Alcohol Abuse and Addiction, 2006). Many individual doctors and the Ameri- can Medical Association fear that the threat of such punish- ment will cause the women who most need prenatal care to

avoid getting it. Developmental scientists ask whether, since every person is powerfully affected by his or her social context, not just pregnant women who drink but also their husbands, mothers, and bartenders should also risk jail.

Of course, that would be madness—millions of people would be jailed. But if that were not done, the law would be se- lectively enforced, and that is a problem as well. Prejudice might also be involved: The four states that do incarcerate preg- nant drinkers (North and South Dakota, Wisconsin, Oklahoma) all have more American Indians than the national average.

Only after a fetus is born does FAS become apparent. To tar- get only one teratogen and to punish women before harm be- comes evident is contrary to the scientific method, which seeks proof. But will scientific caution mean that millions of children will suffer because of substances not yet proven to be terato- gens? If a pregnant woman you knew ordered a glass of wine, would you try to stop her?

fetal alcohol syndrome (FAS) A cluster of birth defects, including abnormal facial characteristics, slow physical growth, and retarded mental development, caused by the mother’s drinking alcohol while pregnant.

Yes, But . . . An adopted boy points out something to his disabled father—a positive interaction between the two. The shapes of the boy’s eyes, ears, and upper lip indicate that he was born with fetal alcohol syndrome. Scientists disagree about a correlation between FAS and drinking alcohol during pregnancy.

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only at birth but for decades afterward, because the damage done by some terato- gens becomes evident only in adulthood. For example, many pregnant women took a drug called DES in the 1960s; their adult children have a higher than average risk of problems with their sex organs.

The clash between the urgency of protecting future children and the caution of the scientific method is further illustrated by the story of fetal alcohol syndrome.

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(continued on page 104)

Risk Reduction 103

TABLE 4.4

Teratogens: Effects of Exposure and Prevention of Damage

Teratogens Effects on Child of Exposure Measures for Preventing Damage Diseases Rubella (German measles)

Toxoplasmosis

Measles, chicken pox, influenza

Syphilis

AIDS

Other sexually transmitted diseases, including gonorrhea and chlamydia

Infections, including infections of urinary tract, gums, and teeth

Pollutants Lead, mercury, PCBs (polychlorinated biphenyls), dioxin, and some pesticides, herbicides, and cleaning compounds

Radiation Massive or repeated exposure to radiation, as in medical X-rays

Social and Behavioral Factors Very high stress

Malnutrition

Excessive, exhausting exercise

Medicinal Drugs Lithium

Tetracycline

Retinoic acid

Streptomycin

ACE inhibitors

Phenobarbital

Thalidomide

Get immunized before becoming pregnant

Avoid eating undercooked meat and handling cat feces, garden dirt

Get immunized before getting pregnant; avoid infected people during pregnancy

Early prenatal diagnosis and treatment with antibiotics

Prenatal drugs and cesarean birth make AIDS transmission very rare.

Early diagnosis and treatment; if necessary, cesarean section, treatment of newborn

Get infection treated, preferably before becoming pregnant

Most common substances are harmless in small doses, but pregnant women should still avoid regular and direct exposure, such as drinking well water, eating unwashed fruits or vegetables, using chemical compounds, eating fish from polluted waters

Get sonograms, not X-rays, during pregnancy; pregnant women who work directly with radiation need special protection or temporary assignment to another job

Get adequate relaxation, rest, and sleep; reduce hours of employment; get help with housework and child care

Eat a balanced diet (with adequate vitamins and minerals, including, especially, folic acid, iron, and vitamin A); achieve normal weight before getting pregnant, then gain 25–35 lbs (10–15 kg) during pregnancy

Get regular, moderate exercise

Avoid all medicines, whether prescription or over-the-counter, during pregnancy unless they are approved by a medical professional who knows about the pregnancy and is aware of the most recent research

In embryonic period, causes blindness and deafness; in first and second trimesters, causes brain damage

Brain damage, loss of vision, mental retardation

May impair brain functioning

Baby is born with syphilis, which, untreated, leads to brain and bone damage and eventual death

Baby may catch the virus. If so, illness and death are likely during childhood.

Not usually harmful during pregnancy but may cause blindness and infections if transmitted during birth

May cause premature labor, which increases vulnerability to brain damage

May cause spontaneous abortion, preterm labor, and brain damage

In the embryonic period, may cause abnormally small head (microcephaly) and mental retardation; in the fetal period, suspected but not proven to cause brain damage. Exposure to background radiation, as from power plants, is usually too low to have an effect.

Early in pregnancy, may cause cleft lip or cleft palate, spontaneous abortion, or preterm labor

When severe, may interfere with conception, implantation, normal fetal development, and full-term birth

Can affect fetal development when it interferes with pregnant woman’s sleep or digestion

Can cause heart abnormalities

Can harm the teeth

Can cause limb deformities

Can cause deafness

Can harm digestive organs

Can affect brain development

Can stop ear and limb formation

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104 CHAPTER 4 ■ Prenatal Development and Birth

Psychoactive Drugs Caffeine

Alcohol

Tobacco

Marijuana

Heroin

Cocaine

Inhaled solvents (glue or aerosol)

TABLE 4.4 (continued from page 103)

Teratogens: Effects of Exposure and Prevention of Damage

Teratogens Effects on Child of Exposure Measures for Preventing Damage

Normal use poses no problem

May cause fetal alcohol syndrome (FAS) or fetal alcohol effects (FAE) (see Thinking Like a Scientist, p. 102)

Increases risk of malformations of limbs and urinary tract, and may affect the baby’s lungs

Heavy exposure may affect the central nervous system; when smoked, may hinder fetal growth

Slows fetal growth and may cause premature labor; newborns with heroin in their blood- stream require medical treatment to prevent the pain and convulsions of withdrawal

May cause slow fetal growth, premature labor, and learning problems in the first years of life

May cause abnormally small head, crossed eyes, and other indications of brain damage

Avoid excessive use: Drink no more than three cups a day of beverages containing caffeine (coffee, tea, cola drinks, hot chocolate)

Stop or severely limit alcohol consumption during pregnancy; especially dangerous are three or more drinks a day or five or more drinks on one occasion

Stop smoking before and during pregnancy

Avoid or strictly limit marijuana consumption

Get treated for heroin addiction before becoming pregnant; if already pregnant, gradual withdrawal on methadone is better than continued use of heroin

Stop using cocaine before pregnancy; babies of cocaine-using mothers may need special medical and educational attention in their first years of life

Stop sniffing inhalants before becoming pregnant; be aware that serious damage can occur before a woman knows she is pregnant

Note: This table summarizes some relatively common teratogenic effects. As the text makes clear, many individual factors in each pregnancy affect whether a given teratogen will actually cause damage and what that damage might be. This is a general summary of what is known; new evidence is reported almost daily, so some of these generalities will change. Pregnant women or women who want to become pregnant should consult with their physicians. Sources: Reece & Hobbins, 2007; Mann & Andrews, 2007; O’Rahilly & Müller, 2001; Shepard & Lemire, 2004; L.T. Singer et al., 2002.

Benefits of Prenatal Care There are many advantages to obtaining early prenatal care (Reece & Hobbins, 2007). Chief among them is protection against teratogens—knowing what medi- cines to avoid and what foods to eat, for instance. Another advantage is that a sono- gram (an image of the fetus, taken with sound waves) allows parents and doctors to see if the fetus is developing normally, to anticipate the due date, and to determine if there is more than one fetus. In addition, at least a dozen tests of substances in the mother’s blood and urine are routinely done, early and again later in pregnancy, to diagnose problems with the fetus. (Table 4.5 provides information about sono- grams and some other prenatal tests.)

Only a few decades ago, most twins came as a surprise to their parents at birth; no more. This information may be life-saving. For instance, in about 15 percent of all twin pregnancies with only one placenta, the bloodstreams of the twins are not separate, and one twin gets too much nourishment from the other. This twin-to- twin transfusion problem often killed both twins, but now it can be detected on a sonogram and treated in mid-pregnancy (Sakata et al., 2006).

Further, since twins are often born too early and too small, a woman carrying twins can try to avoid factors that cause low birthweight, such as poor nutrition,

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work that includes night shifts and hours of standing, or exhaustion and social stress at home (Croteau et al., 2006). Indeed, every woman who learns that her fetus is growing slowly, or that her blood has insufficient iron, or that her blood pressure is climbing, or that she has gestational diabetes can take measures to moderate all these conditions.

Early prenatal care can also prevent the impact of some deadly teratogens. For example, syphilis and AIDS do not harm the fetus if the woman is diagnosed and treated early in pregnancy. Indeed, only a decade ago, 26 percent of women with HIV would pass the virus on to their baby, who often suffered and died in child- hood. Now routine early diagnosis of HIV leads to treatment with antiviral drugs that prevent prenatal transmission of the virus (McDonald et al., 2007; Read, 2005).

Risk Reduction 105

TABLE 4.5

Methods of Postconception Testing

Method Description Risks, Concerns, and Indications Pre-implantation testing

Tests for pregnancy- associated plasma protein (PAPPA) and human chorionic gonadotropin

Alpha-fetoprotein assay

Sonogram (ultrasound)

Chorionic villi sampling (CVS)

Amniocentesis

Not entirely accurate.

Requires surgery, in vitro fertilization, and rapid assessment. This delays implantation and reduces the likelihood of successful birth. It is used only when couples are at high risk of known, testable genetic disorders.

Indicate normal pregnancy, but false positive or false negative results sometimes occur.

Indicate neural-tube defects, multiple embryos (both cause high AFP), or Down syndrome (low AFP). Normal levels change each week; interpretation requires accurate dating of conception.

Reveals problems such as a small head or other body malformations, excess fluid accumulating on the brain, Down syndrome (detected by expert, looking at neck of fetus), and several diseases (for instance, of the kidneys).

Estimates fetal age and reveals multiple fetuses, placental position, and fetal growth, all of which are useful in every pregnancy. Sometimes sex is apparent.

No known risks, unlike the X-rays that it has replaced.

Provides the same information as amniocentesis but can be performed earlier.

Can cause a spontaneous abortion (1%)

Spontaneous abortion caused by the syringe is now very rare (0.05 percent).

Detects chromosomal abnormalities and other genetic and prenatal problems.

The amniotic fluid also reveals the sex of the fetus.

Is done later in pregnancy than other tests, and it takes a week before results are known.

After in vitro fertilization, one cell is removed from each zygote at the four- or eight-cell stage and analyzed.

Blood tests are usually done at about 11 weeks to indicate levels of these substances.

The mother’s blood is tested for the level of alpha-fetoprotein (AFP), now usually done at mid-pregnancy; often combined with other blood tests and repeat sonogram.

High-frequency sound waves are used to produce a “picture” of the fetus as early as 8 weeks. Sonograms are more accurate later in pregnancy to detect less apparent problems, to confirm earlier suspicions, and to anticipate birth complications.

A sample of the chorion (part of the placenta) is obtained (via sonogram and syringe) at about 10 weeks and analyzed. Since the cells of the placenta are genetically identical to the cells of the fetus, this can indicate many chromosomal or genetic abnormalities.

About half an ounce of the fluid inside the placenta is withdrawn (via sonogram and syringe) at about 16 weeks. The cells are cultured and analyzed.

Sources: Eddleman et al., 2006; Malone et al., 2005; K. L. Moore & Persaud, 2003; Newnham et al., 2004; Philip et al., 2004; Wright et al., 2006.

Especially for Social Workers When is it most important to convince women to be tested for HIV: a month before pregnancy, a month after conception, or immediately after birth?

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Pediatric AIDS has almost disappeared from North America and Europe. It is still on the increase in Africa, where prenatal care is scarce and where, even with care, antiviral drugs are often unavailable or unaffordable. Further, the social stigma of HIV/AIDS is so great that some pregnant women fear that their hus- bands and families will abandon them if they suspect they are HIV-positive.

One problem with diagnostic tests done early in pregnancy is that about 20 per- cent of the time, their results suggest that more tests are needed. Many such warnings are “false positives,” a test result that is positive for a birth defect, yet the fetus is actually fine. It is also possible to have a “false negative,” when the test finds no problem but a defect actually does exist. Usually, the cutoff scores for var- ious prenatal tests are set to produce more false positives than false negatives, but in either case, testing can strain a marriage, as the following illustrates.

106 CHAPTER 4 ■ Prenatal Development and Birth

a case to study “What Do People Live to Do?”

John and Martha, graduate students at Harvard, were expecting their second child. Martha was four months pregnant, and her initial prenatal screening revealed an abnormally low level of alpha-fetoprotein (AFP), which could indicate that the fetus had Down syndrome. It was too early for amniocentesis, a more definitive test, so another blood test was scheduled to double- check the AFP level.

John met Martha at a café after a nurse had drawn the sec- ond blood sample but before the laboratory reported the test re- sult. Later, Martha wrote about their conversation.

“Did they tell you anything about the test?” John said. “What exactly is the problem?” . . .

“We’ve got a one in eight hundred and ninety-five shot at a retarded baby.”

John smiled, “I can live with those odds.” I tried to smile back, but I couldn’t. . . . I wanted to tell John

about the worry in my gut. I wanted to tell him that it was more

than worry—that it was a certainty. Then I realized all over again how preposterous that was. “I’m still a little scared.”

He reached across the table for my hand. “Sure,” he said, “that’s understandable. But even if there is a problem, we’ve caught it in time. . . . The worst case scenario is that you might have to have an abortion, and that’s a long shot. Everything’s going to be fine.”

. . . “I might have to have an abortion?” The chill inside me was gone. Instead I could feel my face flushing hot with anger. “Since when do you decide what I have to do with my body?”

John looked surprised. “I never said I was going to decide anything,” he protested. “It’s just that if the tests show something wrong with the baby, of course we’ll abort. We’ve talked about this.”

“What we’ve talked about,” I told John in a low, dangerous voice, “is that I am pro-choice. That means I decide whether or not I’d abort a baby with a birth defect. . . . I’m not so sure of this.”

“You used to be,” said John.

AP P

HO TO

The Legacy of AIDS Orphanages have closed in developed nations because they are no longer needed. In contrast, the need for orphanages is increasing in many parts of the developing world, where AIDS has orphaned 11 million children, according to UNICEF data. These children are in an orphanage in Zim- babwe. Some of them may have inherited the AIDS virus from their parents.

➤Response for Social Workers (from page 105): Testing and then treatment are useful at any time, because women who know they are HIV-positive are more likely to get treatment, reduce risk of transmission, and avoid pregnancy. If pregnancy does occur, early diagnosis is best. Getting tested after birth is too late for the baby.

Especially for Women of Childbearing Age If you have decided to become pregnant soon, you cannot change your genes, your age, or your economic status. But you can do three things in the next month or two that can markedly reduce the risk of having a low- birthweight or otherwise impaired baby a year from now. What are they?

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Before they conceive, many couples discuss whether or not they would carry a severely abnormal fetus to term. But, as the dialogue between Martha and John reveals, couples tend to be much less certain once pregnancy occurs. We will re- turn to this couple at the end of this chapter. In the meantime, consider another difficult case.

Risk Reduction 107

“I know I used to be.” I rubbed my eyes. I felt terribly con- fused. “But now . . . look, John, it’s not as though we’re deciding whether or not to have a baby. We’re deciding what kind of baby we’re willing to accept. If it’s perfect in every way, we keep it. If it doesn’t fit the right specifications, whoosh! Out it goes.”. . .

John was looking more and more confused. “Martha, why are you on this soapbox? What’s your point?”

“My point is,” I said, “that I’m trying to get you to tell me what you think constitutes a ‘defective’ baby. What about . . . oh, I don’t know, a hyperactive baby? Or an ugly one?”

“They can’t test for those things and—” “Well, what if they could?” I said. “Medicine can do all kinds

of magical tricks these days. Pretty soon we’re going to be abort- ing babies because they have the gene for alcoholism, or homo- sexuality, or manic depression. . . . Did you know that in China they abort a lot of fetuses just because they’re female?” I growled. “Is being a girl ‘defective’ enough for you?”

“Look,” he said, “I know I can’t always see things from your perspective. And I’m sorry about that. But the way I see it, if a baby is going to be deformed or something, abortion is a way to keep everyone from suffering—especially the baby. It’s like shoot- ing a horse that’s broken its leg. . . . A lame horse dies slowly, you know? . . . It dies in terrible pain. And it can’t run anymore. So it can’t enjoy life even if it doesn’t die. Horses live to run; that’s

what they do. If a baby is born not being able to do what other people do, I think it’s better not to prolong its suffering.”

“. . . And what is it,” I said softly, more to myself than to John, “what is it that people do? What do we live to do, the way a horse lives to run?”

[Beck, 1999, pp. 132–133, 135]

The second AFP test came back low but in the normal range, “meaning there was no reason to fear that [the fetus] had Down syndrome” (Beck, p. 137).

John thought they had decided to abort a Down syndrome fetus, but his response as they waited for test results had Martha “hot with anger.” As Chapter 3 explains, genetic counselors help couples discuss their choices before becoming pregnant, but John and Martha had no counseling because they hadn’t planned this pregnancy and they were at low risk for any problems, in- cluding chromosomal ones.

The opposite of the false positive is the false negative, a mis- taken assurance that all is well. The second AFP test was in the reassuring normal range. Martha still had “a worry in my gut.” Amniocentesis later revealed that the second AFP was a false negative. The fetus had Down syndrome after all.

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The Same Event, A Thousand Miles Apart: Preparing for Birth The husbands of the pregnant American women (left) are learning to massage their wives dur- ing labor. The pregnant woman in Afghanistan (above) and her doctors discuss why labor will soon be induced: One of her twins is not developing normally. Neither is expected to live. Virtually all newborns in developed nations survive; the Afghani woman has already lost two children at birth.

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SUMMING UP

Risk analysis is a complex but necessary aspect of prenatal development, especially be- cause the placenta does not protect the fetus from all hazards, such as diseases, drugs, and pollutants. Many factors reduce risk, including the mother’s good health and ade- quate nutrition before pregnancy and early prenatal care (to diagnose and treat problems and to teach the woman how to protect her fetus). Risk is affected by dose, frequency, and timing of exposure to teratogens, as well as by the fetus’s genetic vulnerability. Pre- natal testing often reassures the prospective parents but may reveal severe problems that require difficult decisions.

■

The Birth Process For a full-term fetus and a healthy mother, birth can be simple and quick. At some time during the last month of pregnancy, most fetuses change position, turning upside down so that the head is low in the mother’s pelvic cavity. They are now in position to be born in the usual way, head first. About 1 in 20 babies does not turn and is positioned to be born “breech,” that is, buttocks or, rarely, feet first. Obste- tricians sometimes manually turn such fetuses before birth or perform a cesarean section (described below), because breech babies may get insufficient oxygen dur- ing labor (Reece & Hobbins, 2007).

Usually about 38 weeks after conception, the fetal brain signals the release of certain hormones that trigger the woman’s uterine muscles to contract and relax, starting active labor. Uterine contractions eventually become strong and regular, less than 10 minutes apart.

108 CHAPTER 4 ■ Prenatal Development and Birth

a case to study “What Did That Say About Me?”

Tom Horan and his wife saw a sonogram that showed that their fetus’s legs were bowed and shortened. They were told that the condition could be healed through braces, growth hormones, and surgical procedures in childhood, and they began to think about how they would care for a child who needed so much medical attention.

A closer examination by a specialist revealed other deformities: The left arm was missing below the elbow, and the right hand was undeveloped. Sometimes such deformities signify neurological impairment, the doctors told them, but it was impossible to tell for sure.

“Our main concern was the quality of life that the child would have, growing up with such extensive limb deformities, even in the absence of cognitive problems,” Mr. Horan said.

He and his wife, who have three other children, were reared Roman Catholic and had never considered terminating a preg- nancy. Yet even his father, Mr. Horan said, who had long been op- posed to abortion, supported their decision to end the pregnancy.

“Confronted with this question and knowing what we knew,

it changed his mind,” Mr. Horan said. “It’s not just a question of right and wrong; it introduces all sorts of other questions that one has to consider, whether it is the survivability of the child, quality of life of parents, quality of life of siblings, social needs. And it becomes much more real when you’re confronted with an actual situation.”

After the termination, an examination showed . . . an ex- tremely rare condition, Cornelia de Lange syndrome. [The child] would have been severely mentally and physically disabled.

The news was a relief to Mr. Horan, who said he felt sadness and grief, but no regrets. . . . Before the diagnosis, he felt guilt and uncertainty. . . . “I wondered about the ethical implications. . . . What did that say about me?”

[Harmon, 2004, p. 22]

The Horans had to reexamine their values, something they did not think necessary before the sonogram. As one review re- ports, “Most couples say they are both profoundly grateful for the new information and hugely burdened by the choices it forces them to make” (Harmon, 2004, p. 1).

➤Response for Women of Childbearing Age (from page 106): Avoid all drugs (includ- ing legal ones, like nicotine and alcohol), check your weight (gain, or lose, some if you are under, or over, the norm), and receive diagnosis and treatment for any infections— not just sexually transmitted ones but those anywhere in the body, including the teeth and gums.

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The baby is born, on average, after 12 hours of active labor for first births and 7 hours for subsequent births (K. L. Moore & Persaud, 2003), although it is not unusual for labor to take twice, or half, as long. Women’s birthing positions also vary—sitting, squatting, lying down (Blackburn, 2003), or even immersed in warm water. Figure 4.4 shows the sequence of stages in the birth process.

The Newborn’s First Minutes Do you picture just-delivered babies as being held upside down and spanked so that they will start crying and breathing? Wrong. Gentle handling is best, because newborns usually breathe and cry on their own.

Between spontaneous cries, the first breaths cause the infant’s color to change from bluish to pinkish as oxygen begins to circulate. Hands and feet are the last body parts to turn pink. (“Bluish” and “pinkish” refer to the blood color, visible be- neath the skin, and apply to newborns of all skin colors.) The eyes open wide; the tiny fingers grab; the tinier toes stretch and retract. The newborn is instantly, zest- fully ready for life.

Nevertheless, there is much to be done. Mucus in the baby’s throat is removed, especially if the first breaths seem shallow or strained. The umbilical cord is cut to detach the placenta, leaving the “belly button.” The placenta is then expelled. If birth is assisted by a trained worker—as are 99 percent of the births in industrial- ized nations and about half of all births worldwide (Rutstein, 2000)—newborns are weighed, examined to make sure no problems require prompt medical atten- tion, and wrapped to preserve body heat.

The Birth Process 109

Uterus Umbilical cord

Amniotic sac

Cervix Birth canal

Placenta

(a) (b)

(d) (e)

(c)

FIGURE 4.4

A Normal, Uncomplicated Birth (a) The baby’s position as the birth process begins. (b) The first stage of labor: The cervix dilates to allow passage of the baby’s head. (c) Transition: The baby’s head moves into the “birth canal,” the vagina. (d) The second stage of labor: The baby’s head moves through the opening of the vagina (“crowns”) and (e) emerges completely.

Observation Quiz (see answer, page 111): In drawing (e), what is the birth attendant doing as the baby’s head emerges?

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One widely used assessment is the Apgar scale (see Table 4.6). The examiner checks five vital signs—heart rate, breathing, muscle tone, color, and reflexes—at one minute and again at five minutes after birth, assigning each a score of 0, 1, or 2 and totaling all five scores (Moster et al., 2001). The Apgar scale is a quick way for birth attendants to check the baby.

The five-minute Apgar score is the crucial one. An Aus- tralian study found that at one minute, many healthy new- borns look bluish because they are low on oxygen (saturation rate 63 percent), but the blood level of oxygen quickly rises (to 90 percent or more) (Kamlin et al., 2006). If the five- minute total score is 7 or above, all is well.

If the score is below 7, the infant needs help. If the score is below 4, the newborn is in critical condition, and the at- tending physician might page “Dr. Apgar,” which alerts the neonatalist on duty to rush to the delivery room. Fortunately, most newborns are fine, pink, and alert, which reassures the new parents, who cradle their newborn and congratulate each other.

Variations How closely any given birth matches the foregoing description depends on the parents’ preparation for birth, the physical and emotional support provided by birth attendants, the position and size of the fetus, and the customs of the culture. In developed nations, births usually include drugs to dull pain or speed contrac- tions, sterile procedures, and various hospital protocols to be ready for emergen- cies and to avoid lawsuits.

Medical Intervention In about 28 percent of births in the United States, a cesarean section is per- formed. The fetus is removed through incisions in the mother’s abdomen and uterus (Hamilton et al., 2004). The rate of surgical birth varies markedly from place to place, with many developed nations having far fewer cesareans than the United States but others having more (see Figure 4.5).

If serious organic abnormalities are evident, microsurgery on tiny hearts, lungs, and digestive systems has been amazingly successful in recent years. If the new- born needs specialized feeding, or warmth, or extra oxygen, that is also available.

110 CHAPTER 4 ■ Prenatal Development and Birth

TABLE 4.6

Criteria and Scoring of the Apgar Scale

Reflex Respiratory Score Color Heartbeat Irritability Muscle Tone Effort 0

1

2

Blue, pale

Body pink, extremities blue

Entirely pink

Absent

Slow (below 100)

Rapid (over 100)

No response

Grimace

Coughing, sneezing, crying

Flaccid, limp

Weak, inactive

Strong, active

Absent

Irregular, slow

Good; baby is crying

Source: Apgar, 1953.

No Doctor Needed In this Colorado Springs birthing center, most babies are delivered with the help of nurse-midwives. This newborn’s bloody appearance and bluish fingers are com- pletely normal; an Apgar test at five minutes revealed that the baby’s heart was beating steadily and that the body was “entirely pink.”

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Apgar scale A quick assessment of a new- born’s body functioning. The baby’s color, heart rate, reflexes, muscle tone, and res- piratory effort are given a score of 0, 1, or 2 twice—at one minute and five minutes after birth—and the total of all the scores is compared with the ideal score of 10.

cesarean section A surgical birth, in which incisions through the mother’s abdomen and uterus allow the fetus to be removed quickly, instead of being delivered through the vagina. (Also called c-section or simply section.)

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Eighty years ago, 5 percent of all newborns in the United States died (De Lee, 1938). Today almost every newborn lives. The death rate in the first days of life is only 1 in 200, with that one almost always in critical condition at birth be- cause of an obvious problem, such as extremely low birth- weight or massive birth defects.

In developed nations, newborns are tested for various dis- eases. If a problem is confirmed by further testing, parents and medical staff can begin protective measures (such as the diet to prevent PKU, explained in Chapter 3) (MMWR, Oc- tober 15, 2004). Just as during prenatal testing, false posi- tives cause needless worry, and even correct tests may reveal problems that cannot be treated. Nonetheless, most profes- sionals, including those involved with the March of Dimes, advocate testing all newborns for dozens of conditions (Green et al., 2006).

Every year worldwide, obstetricians, midwives, and nurses save millions of lives—of mothers as well as of infants. In- deed, a lack of medical attention during childbirth and illegal abortions are the major reasons why motherhood is still haz- ardous in the least developed nations; about 1 in 20 women in Africa dies of complications of abortion and birth (Daulaire et al., 2002).

However, intervention is not always best for mother and child. In Pelotas, Brazil, most births are by cesarean (82 per- cent for private patients in 2004). The rate of low-birthweight infants in that region of Brazil is rising (from 11 to 16 percent in 10 years) because some infants are born before they are ready (Barros et al., 2005). In general, cesareans are easier for the fetus, and quicker for doctor and mother, but increase the rate of birth complications in later pregnancies (Getahun et al. 2006).

Only 1 percent of U.S. births take place at home—about half of these by choice, attended by a doctor or midwife, and half due to unexpectedly rapid birth. Home births are usually quite normal and healthy, but any complications can be- come more serious while the mother is waiting for emergency medical help (Pang et al., 2002).

In many regions of the world, as modern medicine is introduced, a clash devel- ops between traditional home births attended by a midwife and hospital births at- tended by an obstetrician: Home births risk complications, and hospital births risk too much intervention. All too often, women must choose one or the other, rather than combining the best features of each. An example of such a combination is re- ported regarding the Inuit people of northern Canada:

Until thirty or forty years ago every woman, and most men, learned midwifery skills and knew what to do to help at a birth if they were needed. . . . They helped the woman kneel or squat on caribou skins, and tied the cord with cari- bou sinews. . . . Since the 1950s, as the medical system took control in the belief that hospital birth was safer, more and more pregnant women were evacuated by air to deliver in large hospitals in Winnipeg and other cities. . . . Around three weeks before her due date a woman is flown south to wait in bed and breakfast accommodation for labor to start, and to have it induced if the baby does not ar- rive when expected. Anxious about their children left at home, mothers became bored and depressed. . . . Women . . . deliver in a supine position [on their back]

The Birth Process 111

Rates of Cesarean Sections in Selected Countries

Percent of deliveries

5 10 15 20 25 30 4035

Chad

Egypt

Syria

Colombia

Costa Rica

Venezuela

England

Canada

Mexico

China

Dominican Republic

Brazil

United States

Taiwan

Chile

Sources: Armson, 2007; Belizán et al., 1999; Khawaja et al., 2004; Stanton & Holtz, 2006; Tang et al., 2006.

FIGURE 4.5

Too Many Cesareans or Too Few? Rates of cesarean deliveries vary widely from nation to nation. In general, cesarean births are de- clining in North America and increasing in Africa. Latin America has the highest rates in the world (note that 40 percent of all births in Chile are by cesarean), and sub-Saharan Africa has the lowest. The underlying issue is whether some women who should have ce- sareans do not get them, while other women have unnecessary cesareans.

➤Answer to Observation Quiz (from page 109): The birth attendant is turning the baby’s head after it has emerged; doing this helps the shoulders come out more easily.

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instead of an upright one, which was part of their tradition, and also describe being tied up while giving birth. Many women say that children who have been born in a hospital are different and no longer fit into the Inuit lifestyle. . . . Several new birth centres have now been created [in the Inuit homeland] and nurse-midwives are bringing in traditional midwives as assistants during child- birth, training some Inuit midwives to work alongside them, and at the same time learning some of the old Inuit ways themselves.

[Kitzinger, 2001, pp. 160–161]

Another example of a traditional custom incorporated into a modern birth is the presence of a doula. Long a fixture in many Latin American countries, a doula is a woman who helps other women with labor, delivery, breast-feeding, and new- born care. Increasing numbers of women in North America now hire a profes- sional doula to perform these functions (Douglas, 2002).

From a developmental perspective, such combinations of traditional and modern birthing practices are excellent. Some practices in every culture are helpful and some are harmful to development; a thoughtful combination of traditional and mod- ern is likely to be an improvement over a wholesale rejection of one or the other.

Birth Complications A birth complication includes anything in the newborn, the mother, or the birth process itself that requires special medical attention. When a fetus is already at risk because of a genetic abnormality or exposure to a teratogen, when a mother is unusually young, old, small, or ill, or when labor occurs too soon, birth complica- tions become more likely. Complications usually are part of a sequence of events and conditions that begin long before birth and may continue for years. This means that prevention and treatment must be ongoing. We focus now on one of the most serious complications—lack of oxygen—and one of the most common— low birthweight.

Anoxia Anoxia literally means “no oxygen.” Inadequate oxygen during birth can kill the infant if it lasts longer than a few seconds. Some forms of anesthesia once used during the birth process have been discontinued because they slowed down the delivery of oxygen to the fetus or made it more difficult for a newborn to breathe on its own. Lack of oxygen, even for a few seconds, can cause brain damage, espe- cially in a preterm infant.

112 CHAPTER 4 ■ Prenatal Development and Birth

anoxia A lack of oxygen that, if prolonged during birth, can cause brain damage or death to the baby.

doula A woman who helps with the birth process. Traditionally in Latin America, a doula was like a midwife, the only profes- sional who attended childbirths. Now doulas are likely to work alongside a hospital’s medical staff to help mothers through labor and delivery.

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The Same Event, A Thousand Miles Apart: Back to Basics The physical process of giv- ing birth is the same for all women, but the circumstances vary widely. Many Western women are forgoing the traditional hospital birth in favor of such methods as water birth (left). For women in many developing coun- tries, meanwhile, a sanitary hospital birth would be an improvement—but the hospitals cannot afford even basic supplies. In a deliv- ery room in Afghanistan (right), the doctor is wearing a cooking apron instead of surgical scrubs and an eye mask over her mouth.

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Cerebral palsy (difficulties with movement and speech resulting from brain damage) was once thought to be caused solely by birth procedures: excessive pain medication, slow breech birth, or delivery by forceps (an instrument used to pull the fetus’s head through the birth canal). In fact, however, cerebral palsy often re- sults from genetic vulnerability, worsened by teratogens and a birth that incudes anoxia.

A pair of monozygotic twins were mentioned in Chapter 3, one of whom had a much more severe case of Asperger syndrome than the other. The more severely affected twin also experienced anoxia at birth: He did not begin to breathe on his own; doctors needed to give him oxygen and clear mucus from his throat before he started breathing. That is the likely explanation for his more severe brain damage. Similarly, one reason some people develop schizophrenia is thought to be a bout of anoxia at birth. In both disorders, the underlying problem is genetic, but anoxia can further stress the immature brain.

Anoxia has many causes and is always risky; that’s why the fetal heart rate is monitored during labor and why the newborn’s color is one of the five criteria on the Apgar scale. How long a fetus can experience anoxia without suffering brain damage depends on genes, weight, neurological maturity, drugs in the blood- stream (either taken by the mother before birth or given by the doctor during birth), and a host of other factors.

Low Birthweight The World Health Organization defines low birthweight (LBW) as a weight of less than 51⁄2 pounds (2,490 grams) at birth. The smallest LBW babies are further grouped into very low birthweight (VLBW), a weight of less than 3 pounds, 5 ounces (1,500 grams), and extremely low birthweight (ELBW), a weight of less than 2 pounds, 3 ounces (990 grams). Table 4.7 correlates these birthweights with the various stages of prenatal development.

cerebral palsy A disorder that results from damage to the brain’s motor centers. Peo- ple with cerebral palsy have difficulty with muscle control, so their speech and body movements are impaired.

low birthweight (LBW) A body weight at birth of less than 51⁄2 pounds (2,490 grams).

very low birthweight (VLBW) A body weight at birth of less than 3 pounds, 5 ounces (1,500 grams).

extremely low birthweight (ELBW) A body weight at birth of less than 2 pounds, 3 ounces (990 grams).

The Birth Process 113

End of embryonic period

End of first trimester

At viability (50/50 chance of survival)

End of second trimester

End of preterm period

Full-term

8

13

22

26–28

35

38

1⁄30 oz.

3 oz.

20 oz.

2–3 lb.

51⁄2 lb.

71⁄2 lb.

1 g

85 g

570 g

900–1,400 g

2,490 g

3,400 g

A birthweight less than 2 lb., 3 oz. (965 g) is considered extremely low birthweight (ELBW).

Less than 3 lb., 5 oz. (1,500 g) is very low birthweight (VLBW).

Less than 51⁄2 lb. (2,490 g) is low birthweight (LBW).

Between 51⁄2 and 9 lb. (2,490–4,080 g) is considered normal weight.

*To make them easier to remember, the weights are rounded off (which accounts for the inexact correspondence between metric and nonmetric measures). Actual weights vary. For instance, a normal full-term infant can weigh between 51⁄2 and 9 pounds (2,490 and 4,080 grams); a viable infant, especially one of several born at 26 or more weeks, can weigh less than shown here.

TABLE 4.7

AT ABOUT THIS TIME: Average Prenatal Weights*

Weeks After Weight Weight Period of Development Conception (Nonmetric) (Metric) Notes

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The rate of LBW varies widely from nation to nation (see Figure 4.6). The U.S. rate of 8.2 percent in 2005 has been rising steadily over the past two decades and is now higher than it has been in more than 30 years (see Figure 4.7).

Remember that fetal body weight normally doubles in the last trimester of preg- nancy, with a typical gain of almost 2 pounds (900 grams) occurring in the final three weeks. Thus, in a preterm birth, defined as occurring 3 or more weeks be- fore the standard 38 weeks, the baby usually (though not always) is LBW.

Although most preterm babies are LBW because they missed those final weeks of weight gain, some babies are underweight because they gained weight too slowly throughout pregnancy. They are called small for dates or small for gestational age (SGA). An underweight SGA infant causes more concern than an underweight preterm birth, because SGA signifies impairment during prenatal development.

If a sonogram reveals slow growth, the mother is alerted to see if she can remedy the problem (stop drinking and smoking, eat more, find a less stressful job). But if SGA continues (perhaps because the mother cannot affect it), birth may be induced early or a cesarean performed in order to prevent the neurological consequences of continued slow growth. Newborns who are both preterm and SGA make up the most rapidly increasing category of low-birthweight infants (Ananth et al., 2003).

Normally, in the first months outside the womb, a low-birthweight infant gains weight faster than average (called “catch-up growth”). However, a significant num- ber of SGA infants do the opposite and undereat. They are then likely to be diag- nosed with “failure to thrive,” and be at high risk of becoming mentally slow and

physically small (Casey et al., 2006). Problems with the placenta or umbilical cord can cause SGA, as can maternal illness. However, maternal drug use is a far more common cause. Every psy- choactive drug slows fetal growth.

Tobacco is the worst and the most prevalent cause of SGA, implicated in 25 percent of all LBW births worldwide. Smoking among pregnant women is declining in the United States but rising in many other nations, especially in Asia. This may increase the rates of LBW shown in Figure 4.6. Prescription drugs can also cause low birth- weight. For instance, antidepressants double the incidence of both preterm and SGA infants (Käl- lén, 2004). Some pregnant women need drugs to stave off serious depression, but, as with many measures already mentioned (cesarean sections, genetic testing, anesthesia), the costs and benefits to mother and fetus need to be analyzed case by case (Cohen et al., 2006).

Every psychoactive drug, including prescribed medicines and legal drugs (such as alcohol and nicotine), crosses the placenta and may make a newborn jittery and irritable—signs that the in- fant is withdrawing from that drug. If the mother is heavily addicted (as with heroin or methadone), the newborn may need to be given some of the drug in order to ease withdrawal.

Another common reason for slow fetal growth is maternal malnutrition. Women who begin preg- nancy underweight, who eat poorly during preg-

114 CHAPTER 4 ■ Prenatal Development and Birth

Low-Birthweight Rates in Selected Countries, 1996–2004

LBW infants (percent)

5 10 15 20 25 30

Iceland, Sweden, Republic of Korea (South Korea)

Canada, Norway

China, Ireland, Italy, New Zealand, Spain

Algeria, Argentina, Australia

Japan, United Kingdom, United States

Colombia, Indonesia, Jamaica, Mexico, Thailand, Vietnam

Brazil, Bulgaria, Malaysia

Dominican Republic, Ghana, Kenya, Peru

Congo, Egypt, Nicaragua

Guatemala, Tanzania

Honduras, Mozambique, Nigeria

Pakistan

Haiti

Bangladesh, India

Source: United Nations Development Programme, 2006.

FIGURE 4.6

Low Birthweight Around the World The LBW rate is often considered a reflection of a country’s commitment to its children as well as a reflection of its economic resources.

preterm birth A birth that occurs three or more weeks before the full 38 weeks of the typical pregnancy has elapsed—that is, at 35 or fewer weeks after conception.

small for gestational age (SGA) A term for a baby whose birthweight is significantly lower than expected, given the time since conception. For example, a 5-pound (2,265-gram) newborn is considered SGA if born on time but not SGA if born two months early. (Also called small for dates.)

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nancy, or who gain less than 3 pounds (1,360 grams) per month in the last six months are more likely to have an underweight infant. Ironically, obese women (those with BMI over 30) also are at higher risk of having ELBW infants because serious pregnancy complications, such as preeclampsia, require preterm delivery (G. C. S. Smith et al., 2007) (see Table 4.8). The healthiest pregnancies occur in women who are neither too thin nor too heavy. This conclusion came from a study of all the first births in Scotland over a decade, so it is quite reliable (see Research Design).

Malnutrition (not age) is the primary reason teenage girls often have small ba- bies: If they eat haphazardly and poorly, their diet cannot support their own growth, much less the growth of another developing person (Buschman et al., 2001). Unfortunately, many of the risk factors just mentioned—underweight, un- dereating, underage, and drug use—tend to occur together.

Finally, as you remember from Chapter 3, multiple births are usually LBW. Assisted reproductive technology (ART) has dramatically increased the rate of mul- tiples and thus of LBW (Pinborg et al., 2004). Half of all U.S. in vitro births are multiples.

The Birth Process 115

6.6

7.0

7.4

7.8

8.2

8.6

1960 ’62 ’64 ’66 ’68 ’70 ’72 ’74 ’76 ’78 ’80 ’82 ’84 ’86 ’88 ’90 ’02 ’04’92 ’94 2000’96 ’98

Babies born at low birthweight (percent)

Low-Birthweight Rates in the United States, 1960–2004

Year

Source: Martin et al., 2002; National Center for Health Statistics, 2006.

FIGURE 4.7

Not Improving The LBW rate is often taken to be a measure of a nation’s overall health. In the United States, the rise and fall of this rate are related to many factors, among them prenatal care, maternal use of drugs, overall nutrition, and number of multiple births.

Observation Quiz (see answer, page 116): In what year was 1 out of every 13 U.S. babies (7.5 percent) born weighing less than 51⁄2 pounds (2,490 grams)?

Which Baby Is Oldest? The baby at the left is the oldest, at almost 1 month; the baby at the right is the youngest, at just 2 days. Are you surprised? The explanation is that the 1-month-old was born 9 weeks early and now weighs less than 51⁄2 pounds (2,490 grams); the 2-day-old was full-term and weighs almost 8 pounds (3,600 grams). The baby in the middle, born full-term but weighing only 2 pounds (900 grams), is the most worrisome. Her ears and hands are larger than the preterm baby’s, but her skull is small; malnutrition may have deprived her brain as well as her body.

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Research Design Scientists: Gordon C. S. Smith and four other British researchers.

Publication: American Journal of Public Health (2007).

Participants: All 84,701 women in Scot- land who had their first child between 1991 and 2001, except those with multi- ple births, stillbirths, or births after 43 weeks of gestation.

Design: Correlation of mother’s weight in early pregnancy with birth outcome.

Major conclusion: Obese women have significantly more elective preterm de- liveries (usually because the physician insists), and thus more ELBW infants. The reason is usually preeclampsia (a serious complication during pregnancy), which halts at delivery.

Comment: Although overweight women are less likely to have a sponta- neous preterm birth, obese women risk pregnancy complications. Ideally, women should be neither too thin nor too fat when pregnancy begins.

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Social Support None of the factors that impede or interrupt prenatal growth are inevitable. Qual- ity of medical care, education, culture, and social support affect every developing person before birth, via their impact on the pregnant woman.

The importance of these factors is made starkly evident in data from Gambia, a poor nation in Africa. Preterm births are highest (17 percent) in July, when many women are working long hours in the fields. SGA births are more common (31 percent) in November, the end of the “hungry season,” when most women have been undernourished for three months or more (Rayco-Solon et al., 2005).

Fathers and other relatives, neighbors, cultures, and clinics can reduce risks markedly. For example, the rate of low birthweight among Mexican Americans is lower than the overall U.S. rate, because families are more likely to make sure that their pregnant women do not smoke, drink, or undereat. This is especially true for women who were born in Mexico but give birth in the United States; their babies are remarkably healthy (Aguirre-Molina et al., 2001).

In contrast, there is a high rate of birth complications among women of African American descent, even when they are well nourished, do not use drugs, and ob- tain good prenatal care. One explanation is that the racism of the larger society adds stress to their lives that they cannot shake off, a factor that takes a toll on African Americans’ health overall (Geronimus et al., 2006). Genetic vulnerability is another possibility, but it’s unlikely; women from Africa and the Caribbean who give birth in the United States do not have as many birth complications.

Mothers, Fathers, and a Good Start Birth complications can have a lingering impact on the new family, depending partly on the sensitivity of hospital care (Field, 2001) and the home. In fact, LBW babies are more likely to become adults who are overweight and have health prob- lems, particularly of the heart (Hack et al., 2002). This correlation could result from high levels of stress hormones that the infants experienced in their early days or perhaps because their parents fed them more or raised them differently from other children.

Even when a newborn is small and fragile and must stay in the hospital for weeks after birth, the parents should be encouraged to share in the early caregiving, not only because it benefits the baby but because they, too, are deprived and stressed (Eriksson & Pehrsson, 2005). When the infant’s survival and normality are in doubt, many parents feel inadequate, sad, guilty, or angry. Such emotions become more manageable when the parents touch and care for their vulnerable newborn.

116 CHAPTER 4 ■ Prenatal Development and Birth

TABLE 4.8

Risking Birth Complications: Impact of Mother’s BMI

Incidence of Complication (Percent)

Spontaneous Elective Preterm Preterm ELBW

BMI Preeclampsia Births Births Newborns

Less than 20 (underweight) 2.2% 5.3% 2.5% 0.4%

20–24.9 (healthy weight) 3.0 3.6 2.3 0.3

25–29.9 (overweight) 4.9 3.3 2.7 0.4

30–34.9 (obese) 7.4 3.1 3.6 0.4

More than 35 (morbidly obese) 10.0 3.0 5.0 1.0

Source: G. C. S. Smith et al., 2007.

➤Answer to Observation Quiz (from page 115): In 1998. After having declined, the LBW rate began an upward climb in the mid-1980s.

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One way to achieve parental involvement is through kangaroo care, in which the mother of a low-birthweight infant spends at least an hour a day holding her tiny newborn between her breasts, skin-to-skin, allowing the tiny baby to hear her heart beat and feel her body heat. Fathers also can cradle newborns next to their chests. A comparison study (Feldman et al., 2002) in Israel found that kangaroo- care newborns slept more deeply and spent more time alert than did infants who received standard care. By 6 months of age, infants who had received kangaroo care were more responsive to their mothers. These findings could be the result of either improved infant maturation or increased maternal sensitivity, but either way, this is good news. Other research confirms the benefits of kangaroo care (Ludington-Hoe et al., 2006; Tallandini & Scalembra, 2006).

All humans are social creatures, interacting with their families and their soci- eties. Accordingly, prenatal development and birth involve not only the fetus but also the mother, father, and many others. As you have already read, a woman’s chance of avoiding risks during pregnancy depends partly on her family, her ethnic background, and the nation where she lives.

Help from Fathers Fathers can be crucial. A supportive father-to-be helps a mother-to-be stay healthy, well nourished, and drug-free. Alcohol is not good for a fetus, but neither education nor employment correlates with decreased alcohol consumption during pregnancy. Marriage does (MMWR, April 5, 2002). When it comes to alcohol, at least, husbands seem to help their wives abstain. Overall, a woman’s drug con- sumption and nutrition during pregnancy are power- fully affected by the father’s health habits.

An alternate explanation for the correlation be- tween marriage and healthy newborns is that preg- nancies within marriage are more often wanted and planned by both parents, and that fact in itself en- courages both the pregnant woman and her husband to make sure she takes care of herself. Only about

The Birth Process 117

A Beneficial Beginning These new mothers in a maternity ward in Manila are providing their babies with kangaroo care.

His Baby,Too This new father’s evident joy in his baby illustrates a truism that develop- mental research has only recently reflected: Fathers contribute much more than just half their child’s genes.

kangaroo care A form of child care in which the mother of a low-birthweight infant spends at least an hour a day holding the baby between her breasts, like a kangaroo that carries her immature newborn in a pouch on her abdomen. If the infant is capable, he or she can easily breast-feed in this position.

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half of all U.S. pregnancies are planned; women who are young and unwed are particularly unlikely to become pregnant intentionally.

Not only by example, but also more directly, fathers and other family members can decrease or increase a mother’s stress, which in turn affects her circulation, diet, rest, and digestion and, ultimately, the fetus. One study in northern India found that 18 percent of fathers abused their wives during pregnancy, and the re- sult was a doubling of the rate of fragile newborns and infant death (Ahmed et al., 2006). Another way to see this is that 82 percent of fathers took better care of their wives, to good effect.

The need for social support is mutual. Fathers need reassurance, just as moth- ers do. Levels of cortisol, a stress hormone, correlate between expectant fathers and mothers: When one parent is stressed, the other often is, too (Berg & Wynne- Edwards, 2002), as the following illustrates.

parental alliance Cooperation between a mother and a father based on their mutual commitment to their children. In a parental alliance, the parents agree to support each other in their shared parental roles.

118 CHAPTER 4 ■ Prenatal Development and Birth

This couple’s lack of communication up to this point, and the sudden eruption of previously unexpressed emotions, is not unusual during pregnancy or in the days after birth. Honest discussion between expectant or new parents is difficult, especially because birth raises powerful memories from childhood and irrational fears about the future. Some fathers disappear, either literally or by increasing their work hours. Yet open and intimate communication is crucial if a couple is to form a parental alliance, a cooperative working relationship between two par- ents who raise their child together. The need for a parental alliance is evident in an unexpected, yet common, consequence of birth: postpartum depression.

Postpartum Depression In the days and weeks after birth, between 8 and 15 percent of women experience postpartum depression, a sense of inadequacy and sadness (called baby blues in the mild version and postpartum psychosis in the most severe form) (Perfetti et al., 2004). These rates are for the United States; other nations may be even higher. For example, rates in Pakistan were 36 percent on a standard postpartum scale (Husain et al., 2006). The mother with postpartum depression finds normal baby

a case to study “You’d Throw Him in a Dumpster”

Remember John and Martha, the young couple whose amnio- centesis revealed that their fetus had trisomy-21? Martha de- cided to have the baby, but they had never really discussed the issue. One night at 3:00 A.M., Martha, seven months pregnant, was crying uncontrollably. She told John she was scared.

“Scared of what?” he said. “Of a little baby who’s not as perfect as you think he ought to be?”

“I didn’t say I wanted him to be perfect,” I said. “I just want him to be normal. That’s all I want. Just normal.”

“That is total bullshit. . . . You don’t want this baby to be nor- mal. You’d throw him in a dumpster if he just turned out to be normal. What you really want is for him to be superhuman.”

“For your information,” I said in my most acid tone, “I was the one who decided to keep this baby, even though he’s got Down’s. You were the one who wanted to throw him in a dumpster.”

“How would you know?” John’s voice was still gaining volume. “You never asked me what I wanted, did you? No. You never even asked me. . . .”

[Beck, 1999, p. 255]

This episode ended well, with a long, warm, and honest con- versation between the two prospective parents. Both parents learned what their fetus meant to the other, a topic that had been taboo until that night. Adam, their future son, became an important part of their relationship.

postpartum depression A new mother’s feelings of inadequacy and sadness in the days and weeks after giving birth.

Especially for Fathers-to-Be When does a man’s nongenetic influence on his children begin?

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care (feeding, diapering, bathing) to be very burdensome, and she may have thoughts of neglecting or abusing the infant. Postpartum depression lasting more than a few weeks can have a long-term impact on the child, so it should be diag- nosed and treated as soon as possible.

The father’s reaction is crucial when a mother experiences postpartum depres- sion. His active caregiving is likely to help the baby thrive and the mother to re- cover. Some fathers become depressed themselves after birth. Even if the mother is not depressed, the father’s depression is likely to affect the baby. One study found that sons of fathers who were depressed after their birth had notable behav- ior problems as toddlers (Ramchandani et al., 2005).

From a developmental perspective, some causes predate the pregnancy (such as preexisting depression, financial stress, or marital problems); others occur dur- ing pregnancy (women are more often depressed two months before birth than two months after); and still others are specific to the infant (health, feeding, or sleeping problems) and to the birth (Ashman & Dawson, 2002; Jones, 2006).

The birth experience itself can affect the woman’s well-being. Among those who had babies in the United States between 1993 and 1997, 42 percent had a medical problem (Danel et al., 2003), an added burden for the father as well as the mother. For every woman, birth is stressful, with major hormonal changes, some pain, and a baby who is never exactly what the mother or father anticipated.

Focusing on the parents’ emotions raises the question: To what extent are the first hours crucial for the parent–infant bond, the strong, loving connection that forms as parents hold, examine, and feed their newborn? It has been claimed that this bond develops in the first hours after birth when a mother touches her naked baby, just as sheep and goats must immediately smell and nuzzle their newborns if they are to nurture them (Klaus & Kennell, 1976). However, research does not find that early skin-to-skin contact is essential for humans (Eyer, 1992; Lamb, 1982). Unlike sheep and goats, most other mammals do not need immediate con- tact for parents to nurture their offspring. In fact, substantial research on monkeys begins with cross-fostering, a strategy in which newborns are removed from their biological mothers in the first days of life and raised by another female or even a male. A strong and beneficial relationship sometimes develops (Suomi, 2002).

Most developmentalists hope that mothers, fathers, and newborns strengthen their relationship in the hours and days after birth. That is a good foundation for the difficult days, nights, and years ahead. But bonding immediately after birth is neither necessary nor sufficient for a strong parental alliance and for parent–child attachment throughout life.

SUMMING UP

Most newborns weigh about 71⁄2 pounds (3,400 grams), score at least 7 out of 10 on the Apgar scale, and thrive without medical assistance. Although modern medicine has made maternal or infant death and serious impairment less common in advanced na- tions, many critics deplore the tendency to treat birth as a medical crisis instead of a natural event. Developmentalists note that birth complications are rarely the conse- quence of birth practices alone; prenatal problems are usually involved.

Many factors in the family, fetus, and social conditions lead to low birthweight, a po- tentially serious and increasingly common problem. Postpartum depression is not rare, but, again, factors before and after birth affect how serious and long-lasting this problem is. Human parents and infants seem to benefit from close physical contact following the birth, but it is not essential for emotional bonding. The family relationship begins before conception, may be strengthened by the birth process, and continues lifelong.

The Birth Process 119

A Teenage Mother This week-old baby, born in a poor village in Myanmar (Burma), has a better chance of survival than he might other- wise have had, because his 18-year-old mother has bonded with him.

Especially for Scientists Research with animals can benefit people, but it is sometimes used too quickly to support conclusions about people. When does that happen?

parent–infant bond The strong, loving con- nection that forms as parents hold their newborn.

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120 CHAPTER 4 ■ Prenatal Development and Birth

From Zygote to Newborn 1. The first two weeks of prenatal growth are called the germinal period. During this period, the single-celled zygote develops into a blastocyst with more than 100 cells, travels down the fallopian tube, and implants itself in the lining of the uterus. Most zygotes do not develop.

2. The period from the third through the eighth week after con- ception is called the embryonic period. The heart begins to beat, and the eyes, ears, nose, and mouth begin to form. By the eighth week, the embryo has the basic organs and features of a human, with the exception of the sex organs.

3. The fetal period extends from the 9th week until birth. By the 12th week, all the organs and body structures have formed. The fetus attains viability at 22 weeks, when the brain is sufficiently mature to regulate basic body functions. Babies born before the 26th week are at high risk of death or disability.

4. The average fetus gains approximately 41⁄2 pounds (2,040 grams) during the last three months of pregnancy and weighs 71⁄2 pounds (3,400 grams) at birth. Maturation of brain, lungs, and heart en- sures survival of more than 99 percent of all full-term babies.

Risk Reduction 5. Some teratogens (diseases, drugs, and pollutants) cause physi- cal impairment. Others, called behavioral teratogens, harm the brain and therefore impair cognitive abilities and personality ten- dencies.

6. Whether a teratogen harms an embryo or fetus depends on timing, amount of exposure, and genetic vulnerability. To protect against prenatal complications, good public and personal health practices are strongly recommended.

7. Many methods of prenatal testing inform pregnant couples how the fetus is developing. Such knowledge can bring anxiety and unexpected responsibility as well as welcome information.

The Birth Process 8. Birth typically begins with contractions that push the fetus, head first, out of the uterus and then through the vagina. The Apgar scale, which rates the neonate’s vital signs at one minute and again at five minutes after birth, provides a quick evaluation of the infant’s health.

9. Medical intervention can speed contractions, dull pain, and save lives. However, many aspects of the medicalized birth have been faulted. Contemporary birthing practices are aimed at find- ing a balance, protecting the baby but also allowing more parental involvement and control.

10. Birth complications, such as unusually long and stressful labor that includes anoxia (a lack of oxygen to the fetus), have many causes. Long-term handicaps, such as cerebral palsy, are not inevitable for such children, but careful nurturing from their parents may be needed.

11. Low birthweight (under 51⁄2 pounds, or 2,500 grams) may arise from multiple births, placental problems, maternal illness, malnutrition, smoking, drinking, drug use, and age. Compared with full-term newborns, preterm and underweight babies experi- ence more medical difficulties. Fetuses that grow slowly (SGA) are especially vulnerable.

12. Many women feel unhappy, incompetent, or unwell in the days immediately after giving birth. Postpartum depression may lift with appropriate help; fathers are particularly crucial to the well-being of mother and child, although they also are vulnerable to depression.

13. Kangaroo care is particularly helpful when the newborn is of low birthweight. Mother–newborn interaction should be encour- aged, although the parent–infant bond depends on many factors in addition to birth practices.

germinal period (p. 91) embryonic period (p. 91) fetal period (p. 91) blastocyst (p. 91) placenta (p. 92) implantation (p. 92) embryo (p. 93) fetus (p. 94) age of viability (p. 95)

teratogens (p. 97) behavioral teratogens (p. 97) risk analysis (p. 98) critical period (p. 98) threshold effect (p. 98) interaction effect (p. 99) fetal alcohol syndrome (FAS)

(p. 102) Apgar scale (p. 110)

cesarean section (p. 110) doula (p. 112) anoxia (p. 112) cerebral palsy (p. 113) low birthweight (LBW) (p. 113) very low birthweight (VLBW)

(p. 113) extremely low birthweight

(ELBW) (p. 113)

preterm birth (p. 114) small for gestational age (SGA)

(p. 114) kangaroo care (p. 117) parental alliance (p. 118) postpartum depression (p. 118) parent–infant bond (p. 119)

SUMMARY

KEY TERMS

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Summary 121

6. How much influence do husbands and mothers have on preg- nant women? Explain your answer.

7. How have medical procedures helped and harmed the birth process?

8. Why do hospitals encourage parents of fragile newborns to provide some care, even if the newborn is in critical condition?

9. What are the differences between a typical pregnancy and birth in Africa and a typical one in North America?

10. What can be done about postpartum depression, for mother, father, and infant?

1. What are the major differences between an embryo at 2 weeks and at 8 weeks after conception?

2. What are the factors in achieving viability?

3. Since almost all fetuses born at 30 weeks survive, why don’t women avoid the last month of pregnancy by having an elective cesarean at that time?

4. Which maternal behavior or characteristic seems most harm- ful to the fetus: eating a diet low in folic acid, drinking a lot of al- cohol, or being HIV-positive? Explain your answer.

5. Reconsider the Horans’ decision to abort their fetus. Accord- ing to this published account, which considerations were crucial for them? If you were in this situation, which considerations would be crucial for you?

ing especially any influences of culture, personality, circum- stances, or cohort.

3. People sometimes wonder how any pregnant woman could jeopardize the health of her fetus. Consider your own health- related behavior in the past month—exercise, sleep, nutrition, drug use, medical and dental care, disease avoidance, and so on. Would you change your behavior if you were pregnant? Would it make a difference if your family, your partner, or you yourself did not want a baby?

1. Go to a nearby greeting-card store and analyze the cards re- garding pregnancy and birth. Do you see any cultural attitudes (e.g., variations depending on the sex of the newborn or of the parent)? If possible, compare those cards with cards from a store that caters to another economic or cultural group.

2. Interview three mothers of varied backgrounds about their birth experiences. Make your interviews open-ended—let them choose what to tell you, as long as they give at least a 10-minute description. Then compare and contrast the three accounts, not-

KEY QUESTIONS

APPLICATIONS

➤Response for Scientists (from page 119): Animal research tends to be used too quickly whenever it supports an assertion that is popular but has not been substantiated by research data, as in the social construction about physical contact being crucial for parent–infant bonding.

➤Response for Fathers-to-Be (from page 118): It begins before conception and continues throughout prenatal development, through his influence on the mother’s attitudes and health.

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The First Two Years

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A dults don’t change much in a year or

two. Their hair might grow longer,

grayer, or thinner; they might be a little

fatter; or they might learn something

new. But if you saw friends you hadn’t seen for two

years, you’d recognize them immediately.

By contrast, if you cared for a newborn 24 hours

a day for a month, went away for two years, and

then came back, you might not recognize him or

her, because the baby would have quadrupled in

weight, grown taller by more than a foot, and

sprouted a new head of hair. Behavior would have

changed, too. Not much crying, but some laughter

and fear—including of you.

A year or two is not much compared with the 75

or so years of the average life span. However, in two

years newborns reach half their adult height, talk in

sentences, and express almost every emotion—not

just joy and fear but also love, jealousy, and shame.

The next three chapters describe these radical and

awesome changes.

PA R T I I

123

CHAPTER 5

CHAPTER 6

CHAPTER 7

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The First Two Years: Biosocial Development

In the first two years, rapid growth is obvious in all three domains—body, mind, and social relationships. Here we chronicle biosocial de-velopment: Sit . . . stand . . . walk . . . run! Reach . . . touch . . . grab . . .throw! Listen . . . stare . . . see! Each object, each person, each place becomes something to explore with every sense, limb, and digit.

Invisible developments are even more striking. Infant brains triple in size, with neurons connecting to one another at a dizzying, yet programmed, pace. Tiny stomachs digest more food and more kinds of food, dispatching nour- ishment to the brain and body to enable phenomenal growth.

Parents and cultures are pivotal to this process, which makes it biosocial— not merely biological—development. Adults provide the nurture that enables infant growth, with specifics that change daily because infants change daily. As one expert explains, “Parenting an infant is akin to trying to hit a moving target” (Bornstein, 2002, p. 14).

This chapter describes that target as it moves—not only weight, height, and motor skills at key ages but also the brain growth that provides the foundation for all other developments. You will learn in this chapter how to help the infants you know, and some whom you will never meet, make it safely to age 2.

Body Changes In infancy, growth is so fast, and the consequences of neglect are so severe, that gains need to be closely monitored. Medical checkups, including meas- urement of height, weight, and head circumference, occur every few weeks at first.

Body Size Exactly how rapidly does growth typically occur? We saw in Chapter 4 that at birth the average infant weighs 71⁄2 pounds (3,400 grams) and measures about 20 inches (51 centimeters). This means that the typical newborn weighs less than a gallon of milk and is about as long as the distance from a man’s elbow to the tips of his fingers.

Infants typically double their birthweight by the fourth month and triple it by their first birthday. Physical growth slows in the second year, but it is still rapid. By 24 months most children weigh almost 30 pounds (131⁄2 kilograms)

5

125

CHAPTER OUTLINE

� Body Changes

Body Size Sleep

� Brain Development

Connections in the Brain Necessary and Possible Experiences Implications for Caregivers THINKING LIKE A SCIENTIST:

Plasticity and Orphans

� Senses and Motor Skills

Sensation and Perception Motor Skills Ethnic Variations IN PERSON: The Normal Berger Babies

� Public Health Measures

Immunization Sudden Infant Death Syndrome ISSUES AND APPLICATIONS:

Back to Sleep Nutrition

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and are between 32 and 36 inches (81–91 centimeters) tall. This means that typ- ical 2-year-olds are already half their adult height. They are also about 15 to 20 percent of their adult weight, four times as heavy as at birth. (See Appendix A, pp. A-6, A-7.)

Each of the above numbers is a norm, an average or standard for a particular population. Norms must be carefully interpreted. The “particular population” for the norms above is a representative sample of North American infants, who may be unlike representative samples of infants from other regions of the world. To un- derstand norms, you also need to understand percentiles. A child who is average is at the 50th percentile, a number that is midway between 0 and 100, with half of the children above it and half below it.

Percentiles allow a child’s growth to be compared not only with that of other children but also with his or her own prior development. Pediatricians and nurses notice all children whose growth is far from the norms, but they pay closer atten- tion to the ranking: A drop in percentile means that something might be wrong.

Much of the weight increase in the early months is fat, to provide insulation for warmth and a store of nourishment. This stored nutrition keeps the brain growing

norm An average, or standard, measure- ment, calculated from the measurements of many individuals within a specific group or population.

percentile A point on a ranking scale of 0 to 100. The 50th percentile is the midpoint; half the people in the population rank higher and half rank lower.

126 CHAPTER 5 ■ The First Two Years: Biosocial Development

Both Amazing and Average Juwan’s growth from (a) 4 months to (b) 12 months to (c) 24 months is a surprise and delight to everyone who knows him. At age 2, this Filipino American toddler seems to have become a self-assured, outgoing individual, obviously unique. Yet the norms indi- cate that he is developing right on schedule—weight, teeth, motor skills, and all.

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if teething or the sniffles interfere with eating. When nutrition is temporarily inad- equate, the body stops growing but not the brain—a phenomenon called head- sparing (Georgieff & Rao, 2001). (Chronic malnutrition is discussed later in this chapter.)

Sleep New babies spend most of their time sleeping, about 17 hours or more a day. Throughout childhood, regular and ample sleep correlates with normal brain mat- uration, learning, emotional regulation, and psychological adjustment in school and within the family (Bates et al., 2002; Sadeh et al., 2000). A child who does not sleep well—who wakes up easily or frequently or gets too little sleep—has some kind of health problem, although it is not known if poor sleeping is a cause or a symptom of that problem.

Over the first months, the relative amount of time spent in each type or stage of sleep changes. Newborns apparently dream a lot, or at least they have a high proportion of REM sleep (rapid eye movement sleep, characterized by flickering eyes, dreaming, and rapid brain waves). Dreaming sleep declines over the early weeks, as does “transitional sleep,” the dozing stage when a per- son is half awake. At 3 or 4 months, quiet sleep (also called slow- wave sleep) increases markedly (Salzarulo & Fagioli, 1999).

At about this time, the various “states” of waking and sleeping become more evident. Thus, although many newborns rarely seem sound asleep or wide awake, by 3 months most babies have periods of alertness, when they are neither hungry nor sleepy, and periods of deep sleep, when noises do not waken them.

Sleep patterns are affected by birth order, newborn diet, and child-rearing practices, as well as by brain maturation. For exam- ple, if parents respond to predawn cries with food and play, babies learn to wake up night after night. First-born infants typically

REM sleep Rapid eye movement sleep, a stage of sleep characterized by flickering eyes behind closed lids, dreaming, and rapid brain waves.

head-sparing The biological protection of the brain when malnutrition affects body growth. The brain is the last part of the body to be damaged by malnutrition.

Body Changes 127

The Weigh-In At her 1-year well-baby checkup, Blair sits up steadily, weighs more than 20 pounds, and would scramble off the table if she could. Both Blair’s development and the nurse’s protective arm are quite appropriate.MI

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Dreaming, Dozing, or Sound Asleep? Babies spend most of their time sleeping.

Observation Quiz (see answer, page 128): Can you tell which kind of sleep this infant is experiencing?

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“receive more attention” (Bornstein, 2002, p. 28), and that may be why they exhibit more sleep problems than later-borns. Consider this report from one mother:

I . . . raised my first taking him wherever I went, whenever I went, confident he would adapt. While he was always happy, he was never a good sleeper and his first 4 years were very hard on me (I claim he didn’t sleep through the night until he was 4, but I could be wrong, I was so sleep-deprived). . . . [When my third child] came along . . . , I was determined to give her a schedule. . . . She is a GREAT sleeper, happy to go to bed. I am convinced, anecdotally, that schedules are the most important part of this.

[Freda, personal communication, 1997]

That is good advice. Developmentalists agree that insisting that an infant con- form to the parents’ schedule can be frustrating to the parents and, in some cases, harmful to the infant; but letting a child continually interrupt the adults’ sleep can be harmful to the parents. Ideally, families interact and adapt until every member’s basic needs are met.

One question for many parents is: Where should infants sleep? Traditionally, Western parents put their infants to sleep in a crib in a separate bedroom, unless the family did not have a spare room. Parents in Asia, Africa, and Latin America slept beside their infants, a practice called co-sleeping or bed-sharing.

Today, many Western parents allow bed-sharing, at least in the first months. In fact, a recent survey of British parents found that half of them slept with their infants some of the time (Blair & Ball, 2004). A study of California families found that about a third practiced co-sleeping from birth; about one-fourth of couples had newborns sleep in another room but allowed their toddlers to sleep with them; and the rest kept babies in a separate room throughout childhood (Keller & Goldberg, 2004).

Co-sleeping does not seem to be harmful unless the adult is drugged or drunk—and thus in danger of “overlying” the baby. According to one report:

Mothers instinctively take up a protective posture when sharing a bed with their infants, lying in a fetal position with their lower arm above the infant’s head and the infant lying within around 20–30 centimeters [about 10 inches] from the mother’s chest. The position of the mother’s thighs prevents the baby from slid- ing down the bed.

[Wailoo et al., 2004, p. 1083]

Although a videotape analysis found that co-sleeping infants wake up twice as often (six times a night) as solo-sleeping infants (three times), co-sleepers get just as much sleep as solo sleepers because they go back to sleep more quickly (Mao et al., 2004). Sleeping patterns and practices are like other aspects of infant care: Many different paths can lead to normal child development and normal family functioning.

SUMMING UP

Birthweight doubles, triples, and quadruples by 4 months, 12 months, and 24 months, re- spectively. Height increases by about a foot (about 30 centimeters) in the first two years. Such norms are useful as general guidelines, but individual percentile rankings over time indicate whether a particular infant is growing normally. Sleep becomes regular, dreaming less common, and distinct sleep–wake patterns develop, usually including a long night’s sleep by age 1. Time spent dreaming decreases to about what it is for an older child. Cultural and caregiving practices influence norms, schedules, and expectations.

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Especially for New Parents You are aware of cultural differences in sleeping practices, and this raises a very practical issue: Should your newborn sleep in bed with you?

128 CHAPTER 5 ■ The First Two Years: Biosocial Development

co-sleeping A custom in which parents and their children (usually infants) sleep together. (Also called bed-sharing.)

➤Answer to Observation Quiz (from page 127): The baby’s outstretched left arm suggests dreaming, which occupies about six hours of every day’s sleep at this age. Direct observation or a video, not a photograph, could demonstrate whether this is REM (dreaming) sleep. Quiet sleep is characterized by shallow breathing, still eyes, and relaxed muscle tone.

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Brain Development Recall that the newborn’s skull is disproportionately large. That’s because it must be big enough to hold the brain, which at birth is already 25 percent of its adult weight. The neonate’s body, by comparison, is typically only 5 per- cent of the adult weight. By age 2, the brain is almost 75 percent of adult brain weight; the child’s total body weight is only about 20 percent of its adult weight (see Figure 5.1).

Connections in the Brain Head circumference provides a rough idea of how the brain is growing, and that is why medical checkups include measurement of the skull. The dis- tance around the head typically increases about 35 percent (from 13 to 18 inches, or from 33 to 46 centimeters) within the first year. Much more sig- nificant (although harder to measure) are changes in the brain’s communication system. To understand this, we review the basics of neurological development (see Figure 5.2).

Basic Brain Structures The brain’s communication system begins with nerve cells, called neurons. Most neurons are created before birth, at a peak production rate of 250,000 new brain cells per minute in mid-pregnancy (Bloom et al., 2001). In infancy, the human brain has billions of neurons. Some neurons are deep inside the brain or in the brain stem, a region that controls automatic responses such as heartbeat, breath- ing, temperature, and arousal. About 70 percent of neurons are in the cortex, the brain’s six outer layers (sometimes called the neocortex) (Kolb & Whishaw, 2003). The cortex is crucial for humans, as is evident in the following three facts:

■ About 80 percent of the human brain material is in the cortex. ■ In other mammals the cortex is proportionally smaller, and non-mammals

have no cortex. ■ Most thinking, feeling, and sensing take place in the cortex, although other

parts of the brain join in (Kolb & Whishaw, 2003).

Brain Development 129

0

25

50

75

100

Brain weight

Height Weight

Percentage of adult size

In Just the First Two Years . . .

FIGURE 5.1

Growing Up Two-year-olds are barely talking and are totally dependent on adults, but they have already reached half their adult height and three-fourths of their adult brain size. This is dramatic evidence that biosocial growth is the foundation for cognitive and social maturity.

Frontal cortex The front part of the cortex assists in planning, self-control, and self-regulation. It is very immature in the newborn.

Auditory cortex Hearing is quite acute at birth, the result of months of eavesdropping during the fetal period.

Cortex The crinkled outer layer of the brain (colored here in pink, tan, purple, and blue) is the cortex.

Visual cortex Vision is the least mature sense at birth because the fetus has nothing to see while in the womb.

FIGURE 5.2

The Developing Cortex The infant’s cortex consists of four to six thin layers of tissue that cover the brain. It contains virtually all the neurons that make conscious thought possible. Some areas of the cortex, such as those devoted to the basic senses, mature relatively early. Others, such as the frontal cortex, mature quite late.

neuron One of the billions of nerve cells in the central nervous system, especially the brain.

cortex The outer layers of the brain in humans and other mammals. Most thinking, feeling, and sensing involve the cortex. (Sometimes called the neocortex.)

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Various areas of the cortex specialize in particular functions. For instance, there is a visual cortex, an auditory cortex, and an area dedicated to the sense of touch for each body part—even for each finger of a person or, in rats, for each whisker (Bloom et al., 2001). Regional specialization within the cortex occurs not only for motor skills and senses but also for particular aspects of cognition.

One of the fascinating aspects of brain specialization is that a particular part of the brain (called the fusiform face area) seems dedicated to perception of faces. In newborns, this area is activated not only by real faces but also by visual stimuli (e.g., pictures) that look like faces. The infant’s experiences refine perception in this area, so 6-month-olds recognize their mothers and fathers, examine faces of strangers, and no longer pay careful attention to monkey faces (Johnson, 2005).

Within and between brain areas, neurons are connected to other neurons by in- tricate networks of nerve fibers called axons and dendrites (see Figure 5.3). Each neuron has a single axon and numerous dendrites, which spread out like the branches of a tree. The axon of one neuron meets the dendrites of other neurons at intersections called synapses, which are critical communication links within the brain. To be more specific, neurons communicate by sending electrochemical impulses through their axons to synapses, to be picked up by the dendrites of other neurons. The dendrites bring the message to the cell bodies of their neurons, which, in turn, convey the message via their axons to still other neurons. Axons and den- drites do not touch at synapses. Instead, the electrical impulses in axons typically cause the release of chemicals called neurotransmitters, which carry information

130 CHAPTER 5 ■ The First Two Years: Biosocial Development

Dendrites receive messages from other neurons

Neuron Axon sends messages to other cells

Axon

Synapse Dendrite

Neurotransmitters

Myelin covering the axon speeds transmission of neural impulses

In the synapse, or intersection between an axon and dendrite, neurotransmitters carry information from one neuron to another.

FIGURE 5.3

How Two Neurons Communicate The link between one neuron and another is shown in the simplified dia- gram at right. The infant brain actually contains billions of neurons, each with one axon and many dendrites. Every electrochemical message to or from the brain causes thousands of neurons to fire simultaneously, each transmitting the message across the synapse to neighboring neurons. The electron micrograph directly above shows several neurons, greatly magnified, with their tangled but highly organized and well-coordinated sets of dendrites and axons.

axon A fiber that extends from a neuron and transmits electrochemical impulses from that neuron to the dendrites of other neurons.

dendrite A fiber that extends from a neuron and receives electrochemical impulses transmitted from other neurons via their axons.

synapse The intersection between the axon of one neuron and the dendrites of other neurons.

➤Response for New Parents (from page 128): From the psychological and cultural perspectives, babies can sleep anywhere as long as the parents can hear them if they cry. The main consideration is safety: Infants should not sleep on a mattress that is too soft, nor should a baby sleep beside an adult who is drunk or drugged or sleeps very soundly (Nakamura et al., 1999). Otherwise, the family should decide for itself where its members would sleep best.

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from the axon of the sending neuron, across the synaptic gap, to the dendrites of the receiving neuron, a process speeded up by myelination (described in Chapter 8).

Transient Exuberance and Pruning At birth, the brain contains more than 100 billion neurons, more than any person will ever use (de Haan & Johnson, 2003). By contrast, the newborn brain has far fewer den- drites and synapses than the person will eventually possess. During the first months and years, rapid growth and refine- ment in axons, dendrites, and synapses occur, especially in the cortex. Dendrite growth is the major reason that brain weight triples in the first two years (Johnson, 2005).

An estimated fivefold increase in dendrites in the cortex occurs in the 24 months after birth, with about 100 trillion synapses being present at age 2 (Schwartz & Begley, 2002). This early growth is called transient exuberance, because the expanded growth of dendrites is followed by pruning (see Figure 5.4), in which unused neurons and miscon- nected dendrites atrophy and die (Barinaga, 2003). (This process is called pruning because it resembles the way a gardener might prune a rose bush by cutting away some stems to enable more, or more beautiful, roses to bloom.) Transient exuberance enables neurons to become connected to, and com- municate with, a greatly expanding number of other neurons within the brain. Synapses, dendrites, and even neurons continue to form and die throughout life, though more rapidly in infancy than at any other time (Nelson et al., 2006).

Thinking and learning require that such connections between many parts of the brain be made. For example, to understand any word in this text, you need to understand the surrounding words, the ideas they convey, and how they relate to your other thoughts and experiences. Baby brains have the same requirement, al- though at first they have few experiences to build on, and the various parts of the brain have not yet developed to the adult level or even to the level of a 2-year-old.

Brain Development 131

1 2 3 4 5 6 7 8 9 10 11 12 21 12 13 14 15 163 4 5 6 7 8 9 10 11

Months Years

Age

Receptive language areas/ speech production

(angular gyrus/Broca's area)

Higher cognitive functions (prefrontal

cortex)

Seeing/hearing (visual cortex/

auditory cortex)

Synapse Formation and Dendrite Formation

Source: Adapted from R. A. Thompson & C. A. Nelson, 2001, p. 8.

FIGURE 5.4

Brain Growth in Response to Experience These curves show the rapid rate of experience- dependent synapse formation for three functions of the brain (senses, language, and analysis). After the initial increase, the underused neurons are gradually pruned, or inactivated, as no func- tioning dendrites are formed from them.

Observation Quiz (see answer, page 132): Why do both “12 months” and “1 year” appear on the “Age” line?

Electric Excitement Milo’s delight at his mother’s facial expressions is visible, not just in his eyes and mouth but also in the neurons of the outer layer of his cortex. Electrodes map his brain activation region by region and moment by moment. Every month of life up to age 2 shows increased electrical excitement.

transient exuberance The great increase in the number of dendrites that occurs in an infant’s brain during the first two years of life.

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Experience Shapes the Brain The specifics of brain structure and growth depend on genes but also on experience, which produces the “postnatal rise and fall” of synapses (de Haan & Johnson, 2003, p. 5). Soon after exuberant expansion, some dendrites wither away because they are underused—that is, no experiences have caused them to send a message to the axons of other neurons. Strangely enough, this loss increases brain power by promoting a more intricate organization of existing connections; the “increasing cognitive complexity of childhood is related to a loss rather than a gain of synapses” (de Haan & Johnson, 2003, p. 8).

Further evidence of the benefit of cell death comes from neurological research regarding fragile X syndrome (described in Chapter 3), which includes “a persistent failure of normal synapse pruning” (Irwin et al., 2002, p. 194). In children with fragile X syndrome, dendrites are too dense and too long; without pruning, children cannot think normally.

Stress and the Brain An unfortunate example of the role of experience in brain development begins when the brain produces cortisol and other hormones in response to stress, which happens throughout life (Gunnar & Vasquez, 2001). If the brain produces an over- abundance of stress hormones early in life (as when an infant is frequently terri- fied), then the brain becomes incapable of normal stress responses. Later, that person’s brain may either overproduce stress hormones, making the person hyper- vigilant (always on the alert), or underproduce them, making the person emotion- ally flat (never happy, sad, or angry).

A kindergarten teacher might notice that one child becomes furious or terrified at a mild provocation and another child seems indifferent to everything. Why? In both cases, the underlying cause could be excessive stress-hormone production in infancy, which changes the way the brain responds to stress. Similarly, if an adult loves or hates too quickly, extremely, and irrationally, the cause could be abnormal brain hormones resulting from early experiences such as abuse (Teicher, 2002).

Necessary and Possible Experiences A scientist named William Greenough has identified two experience-related as- pects of brain development (Greenough et al., 1987):

■ The development of experience-expectant brain functions requires the individual’s exposure to basic common experiences—experiences that almost every infant has and all infants need for normal brain development.

■ The development of experience-dependent functions depends on the indi- vidual’s exposure to particular, variable experiences—experiences that some infants in some families and cultures may have but others may not have, and which vary from one infant to another.

The basic, common experiences must happen for normal brain maturation to occur, and they almost always do happen: The brain is designed to expect them and use them for growth. Human brain development is dependent on many such expected experiences. In deserts and in the Arctic, on isolated farms and in crowded cities, almost all babies do have things to see, objects to manipulate, and people to love them. As a result, their brains develop normally.

In contrast, dependent experiences might happen; because of them, one brain differs from another. Particular experiences vary, such as which language babies hear or how their mother reacts to frustration. Depending on those particulars, infant brains are structured and connected one way or another, as some dendrites

experience-expectant Refers to brain functions that require certain basic com- mon experiences (which an infant can be expected to have) in order to develop normally.

experience-dependent Refers to brain func- tions that depend on particular, variable experiences and that therefore may or may not develop in a particular infant.

132 CHAPTER 5 ■ The First Two Years: Biosocial Development

➤Answer to Observation Quiz (from page 131): “One year” signifies the entire year, from day 365 to day 729, and that is indicated by its location between “12 months” and “2 years.”

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grow and neurons thrive while others die. Consequently, all people are similar, but each person is unique, be- cause of particular early experiences.

This distinction can be made for all mammals. Some of the most persuasive research has been done with songbirds. All male songbirds have a brain region dedi- cated to listening and reproducing sounds (experience- expectant), but each species in a particular locality learns to produce a slightly different song (experience- dependent) (Knudsen, 1999). Birds develop the neu- rons that they need: neurons dedicated to learning new songs (canaries) or to finding hidden seeds (chicka- dees). Both of these functions require experiences that circumstances offer to some birds but not to others (Barinaga, 2003).

In unusual situations, knowledge of which develop- mental events are experience-expectant at what ages is helpful. For example, proliferation and pruning occur at about 4 months in the visual and auditory cortexes. For this reason, treatment of blind or deaf infants (whether with surgery, eyeglasses, or hearing aids) should occur early in life to prevent atrophy of those brain regions that expect sights and sounds (Leonard, 2003). Thus, deaf infants whose deficits are recognized at birth and remediated in their first year become better at understanding and expressing language than do those whose hearing deficits are not noticed until later (Kennedy et al., 2006).

If early visual or auditory neuronal connections are not made, those areas of the brain may become dedicated to other senses, such as touch. Braille, for that rea- son, is easier for a blind person to read than for a seeing person, because blind people often have more brain cells dedicated to the sense of touch (Pascual-Leone & Torres, 1993).

The language areas of the brain develop most rapidly between the ages of 6 and 24 months, so infants need to hear a lot of speech during that period in order to talk fluently. In fact, speech heard between 6 and 12 months helps infants recog- nize the characteristics of their local language long before they utter a word (Saf- fran et al., 2006).

The last part of the brain to mature is the prefrontal cortex, the area for anticipation, planning, and impulse control. It is virtually inactive in early infancy but gradually becomes more efficient over the years of childhood and adolescence (Luciana, 2003). Thus, telling an infant to stop crying is pointless, because the infant cannot decide to stop crying. Such decisions require brain functions that are not yet present.

Much worse is for an adult to become angry and shake the baby to stop the crying. This can cause shaken baby syndrome, a life-threatening condition that occurs when an infant is held by the shoulders and shaken back and forth, sharply and quickly. The shaking stops the crying because of ruptured blood vessels in the brain and broken neural connections. In the United States, brain scans show that more than one in five of all children hospitalized for maltreatment suffer from shaken baby syndrome (Rovi et al., 2004).

Implications for Caregivers What does early brain development mean for parents and other caregivers? First, early brain growth is rapid and dependent on experience. This means that caress- ing a newborn, talking to a preverbal infant, and showing affection toward a toddler

Brain Development 133

Let’s Talk Infants evoke facial expressions and baby talk, no matter where they are or which adults they are with. Communication is thus experience-expectant: Young human brains expect it and need it.

Observation Quiz (see answer, page 134): Are these two father and daughter? Where are they?

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prefrontal cortex The area of cortex at the front of the brain that specializes in antici- pation, planning, and impulse control.

shaken baby syndrome A life-threatening condition that occurs when an infant is forcefully shaken back and forth, rupturing blood vessels in the brain and breaking neural connections.

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may be essential to develop the child’s full potential. If such experiences are miss- ing from the child’s early weeks and months, lifelong damage may result.

Second, each part of the brain has a sequence of growing, connecting, and pruning. Some kinds of stimulation are meaningless before the brain is ready, and some potential learning is irrelevant to a particular person. That means it is advis- able to follow the baby’s lead to figure out what stimulation is needed. Infants re- spond most strongly and positively to whatever their brains need; that is why very young babies like to look at and listen to musical mobiles, strangers on the street, and, best of all, their own caregivers.

This preference reflects self-righting, the inborn drive to remedy deficits. An infant with limited stimulation will develop the brain by using whatever experi- ences are available. Babies do not need the latest educational toys—their brains will develop with normal stimulation. Just don’t keep them in a dark, quiet place all day long.

Human brains are designed to grow and adapt; some plasticity is retained throughout life (Baltes et al., 2006). Brains protect themselves from overstimula- tion; for example, overstimulated babies sometimes cry or sleep. They also adjust to understimulation, responding to any experience by developing new connections lifelong (Greenough, 1993; Schwartz & Begley, 2002).

Neuroscientists once thought that brains were influenced solely by genes and prenatal influences. By contrast, many social scientists once thought that child- hood environment was crucial. Cultures (according to anthropologists) or societies (according to sociologists) or parents (according to psychologists) could be credited or blamed for a child’s emotions and actions.

Now most scientists, especially life-span developmentalists, are multidiscipli- nary, incorporating perspectives from both neuroscience and social science (Nelson et al., 2006). They believe that plasticity is an “inherent property of devel- opment” (Johnson, 2005, p. 189), but they do not think plasticity is unlimited. Rather, there are sensitive periods, which are times when particular kinds of development are primed to occur (Baltes et al., 2006). The first two years of life are widely considered a sensitive period during which the brain needs some experiences if it is to develop normally.

For an explanation of why social scientists let go of their faith in the brain’s ability to recover from deprivation at any age, read the following.

self-righting The inborn drive to remedy a developmental deficit.

sensitive period A time when a certain kind of growth or development is most likely to happen or happens most readily.

134 CHAPTER 5 ■ The First Two Years: Biosocial Development

thinking like a scientist Plasticity and Orphans

How much, and when, can experience affect the brain? Two studies—one involving caged rats and the other involving adopted babies—provide some answers.

In research by Marion Diamond, William Greenough, and their colleagues, some “enriched” rats were raised with other rats in large cages filled with interesting rat toys; other “deprived” rats were isolated in small, barren cages. The rats were randomly assigned, and all came from the same few litters. At autopsy, their brains were examined. The brains of the “enriched” rats were larger and heavier and had more dendrites than the brains of the “deprived” rats (Diamond et al., 1988; Greenough & Volkmar, 1973).

Many other researchers have confirmed this phenomenon: Isolation and sensory deprivation harm the developing brain of a rat, and a complex social environment enhances neurological growth (Curtis & Nelson, 2003). The most recent extensions of this research suggest that rats raised in cognitively stimulating environments are less likely to suffer from brain disease, includ- ing Alzheimer’s disease, in late adulthood.

Such experiments are unthinkable with humans, but a chill- ing natural experiment began in Romania in the 1980s, when dictator Nicolae Ceausesçu forbade all birth control and out- lawed abortions except for women who had five children or more. Parents were paid for every birth but received no financial

➤Answer to Observation Quiz (from page 133): The man’s straight black hair, high cheekbones, and weather-beaten face indicate that he could be an Indian from North or South America. Other clues pinpoint the location more closely. Note his lined, hooded jacket and the low, heat-conserving ceiling of the house—he is an Inuit in northern Canada. A father’s attention makes a baby laugh and vocalize, not look away, so this man is not the 6-month-old baby’s father. She is being held by a family friend whom she is visiting with her parents.

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Brain Development 135

support for raising a child. Illegal abortions became the leading cause of death for women age 15–45 (Verona, 2003), and more than 100,000 children were abandoned to crowded, impersonal state-run orphanages (D. E. Johnson, 2000). These children were overstressed and overstimulated because they lacked the buffers of social reassurance and love. They experienced “severe and pervasive restriction of human interactions, play conversa- tion, and experiences” (Rutter & O’Connor, 2004, p. 91).

Ceausesçu was ousted and killed in 1989. During the next two years, thousands of Romanian children were adopted by North American and western European families who believed that “lots of love and good food would change the skinny, floppy waif they found in the orphanage into the child of their dreams” (D. E. Johnson, 2000, p. 154).

All the Romanian adoptees experienced catch-up growth, becoming taller and gaining weight until they reached normal size (Rutter & O’Connor, 2004). However, many showed signs of emotional damage: They were too friendly to strangers, or too angry without reason, or too frightened of normal events (Chisholm, 1998). The children who fared best were adopted before 6 months of age (Rutter, 2006).

For scientists who expected dire consequences, the news was good: “The human infant has built-in ‘buffers’ against early adversity” (O’Connor et al., 2000). Self-righting was apparent, especially in weight and height. By age 11, children who had been adopted by 6 months were normal in IQ and in other ways.

For those who hoped for the eventual recovery of all these children, however, the news was bad. No further gains occurred after age 6, except for the most severely impaired children, who were still below average. The 11-year-olds who had been adopted after they were 6 months old scored an average of 85 on the WISC IQ test, which is 15 points below normal. Depriva- tion was also apparent in language and social interaction, abili- ties controlled by the cortex.

Research on maltreated children in the United States has reached similar conclusions. If maltreatment begins early in life and continues past 1 year, complete social and emotional recov- ery is much more elusive than catch-up physical growth (Bolger & Patterson, 2003). Plasticity is not infinite; some effects of early deprivation probably persist no matter how nurturant later

life is (Rutter, 2006). On the other hand, some plasticity is evi- dent throughout life; some research focuses on a 6-month window, others a year, others two years. Ideally of course, no deprivation occurs at all.

Neither dire nor sunny predictions about maltreated children are accurate. A team of scientists who have devoted their lives to impaired children advise: “Be skeptical about ‘miracle’ cures of severely affected individuals which appear in the media, or even in scientific journals, while recognizing that partial amelioration can occur in individual cases” (Clarke & Clarke, 2003, p. 131).

Thinking like a scientist means working to stop every govern- ment, culture, or family that allows young children to be raised without the experiences they need in order to develop normally. Head-sparing, plasticity, self-righting, and experience-expectant events all compensate for the many imperfections and lapses of human parenting, but they cannot overcome extreme early dep- rivation that lasts too long.

A Fortunate Pair Elaine Himelfarb (shown in the background), of San Diego, California, is shown here in Bucharest to adopt 22-month-old Maria. This adoption was an exception to the Romanian government’s ban at the time on international adoptions. Adopted children like Maria, who have been well fed and who are less than 2 years old, are especially likely to develop well.

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SUMMING UP

Brain growth is rapid during the first months of life, when dendrites and the synapses within the cortex increase exponentially. By age 2 the brain already weighs three-fourths of its adult weight. Shrinkage of underused and unconnected dendrites begins in the sensory and motor areas and then occurs in other areas. Although some brain develop- ment is maturational, experience is also essential—both the universal experiences that almost every infant has (experience-expectant brain development) and the particular ex- periences whose nature depends on the child’s family or culture (experience-dependent brain development).

■

Especially for Social Workers An infertile couple in their late 30s asks for your help in adopting a child from eastern Europe. They particularly want an older child. How do you respond?

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Senses and Motor Skills You learned in Chapter 2 that Piaget called the first period of intelligence the sensorimotor stage, emphasizing that cognition develops from the senses and motor skills. The same concept—that infant brain development depends on sensory experiences and early movements—underlies the discussion you have just read.

For that reason, within hours of birth, doctors and nurses make sure the vital organs are functioning, assessing basic senses and motor responses. Many of them use the Brazelton Neonatal Assessment Scale, which measures 26 items of newborn behavior (such as cuddling, listening, and self-soothing) as well as several reflexes. Now we describe the sequence in which these abilities—all very immature at birth—develop.

Sensation and Perception All the senses function at birth. Newborns have open eyes, sensitive ears, and re- sponsive noses, tongues, and skin. Throughout their first year, infants use their senses to sort and classify their many experiences. Indeed, “infants spend the better part of their first year merely looking around” (Rovee-Collier, 2001, p. 35).

You may have noticed that very young babies seem to attend to everything, without focusing on anything in particular. Up until about age 1, taste is one of the primary ways humans learn about objects. Babies bring everything to their mouths as soon as they can do so (Adolph & Berger, 2005).

Since all of a newborn’s senses function, why don’t newborns seem to perceive much? To understand this, you need to understand the distinction between sensa- tion and perception. Sensation occurs when a sensory system detects a stimulus, as when the inner ear reverberates with sound or the retina and pupil of the eye intercept light. Thus, sensations begin when an outer organ (eye, ear, skin, tongue, or nose) meets anything in the external world that can be seen, heard, touched, tasted, or smelled.

Perception occurs when the brain notices and processes a sensation. Percep- tion occurs in the cortex, usually as the result of a message from one of the sensing organs—a message that experience suggests might be worth interpreting. Some sensations are beyond comprehension at first: A newborn does not know that the letters on a page might have significance, that Mother’s face should be distin- guished from Father’s face, or that the smells of roses and garlic have different connotations. Perceptions require experience.

Infant brains are especially attuned to experiences that are repeated, striving to make sense of them (Leonard, 2003). Thus, newborn Emily has no idea that Emily is her name, but she has the brain capacity to hear sounds in the usual speech range (not the high sounds that only dogs can hear) and an inborn prefer- ence for repeated patterns. At about 4 months, especially when her auditory cor- tex is rapidly creating and pruning dendrites, the repeated word Emily is perceived as well as sensed, and the sound is associated with attention from other people (Saffran et al., 2006).

Before 6 months, Emily may open her eyes and turn her head when her name is called, and she associates the words Mommy and Daddy with those people. It will take many more months before she tries to say “Emmy” and still longer before she knows that Emily is indeed her name or what a mother and father are.

Thus, cognition goes beyond perception. It occurs when people think about and interpret what they have perceived. (Later, cognition no longer requires sensa- tion and perception: People can imagine, fantasize, hypothesize.) There is a sequence of comprehension, from sensation to perception to cognition. A baby’s

sensation The response of a sensory system (eyes, ears, skin, tongue, nose) when it detects a stimulus.

perception The mental processing of sensory information, when the brain interprets a sensation.

136 CHAPTER 5 ■ The First Two Years: Biosocial Development

Especially for Parents of Grown Children Suppose that you realize that you seldom talked to your children until they talked to you and that you never used a stroller or a walker but put them in cribs and playpens. Did you limit their brain growth and their sensory capacity?

➤Response for Social Workers (from page 135): Tell them that such a child would require extra time and commitment, more than a younger adoptee would. Ask whether both are prepared to cut down on their working hours in order to meet with other parents of international adoptees, to obtain professional help (for speech, nutrition, physical development, and/or family therapy), and to help the child with schoolwork, play dates, and so on. You might encourage them instead to adopt a special-needs child from their own area, to become foster parents, or to volunteer at least 10 hours a week at a day-care center. Their response would indicate their willingness to help a real—not imagined—child. If they demonstrate their understanding of what is required, then you might help them adopt the child they want.

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sense organs must function if this sequence is to begin. No won- der the parts of the cortex dedicated to the senses develop rapidly: That is the prerequisite for the other developments.

Hearing The sense of hearing is already quite acute at birth. Certain sounds seem to trigger reflexes, even without conscious percep- tion. Sudden noises startle newborns, making them cry; rhythmic sounds, such as a lullaby or a heartbeat, soothe them and put them to sleep. Even in the first days of life, infants turn their heads toward the source of a sound, and they soon begin to adapt that response to connect sight and sound with increasing accuracy (Morrongiello et al., 1998).

Young infants are particularly attentive to the human voice, developing rapid comprehension of the rhythm, segmentation, and cadence of spoken words long before comprehension of their meaning (Saffran et al., 2006). As time goes on, sensitive hearing combines with the developing brain to distinguish patterns of sounds and syllables.

Infants become accustomed to the rules of their language, such as which sylla- ble is usually stressed (various English dialects have different rules), whether changing voice tone is significant (as it is in Chinese), whether certain sound combinations are often or never repeated, and so on. All this is based on very care- ful listening to human speech, even speech not directed toward them and uttered in a language they do not yet understand.

Seeing Vision is the least mature sense at birth. Although the eyes open in mid-pregnancy and are sensitive to bright light (if the woman is sunbathing in a bikini, for in- stance), the fetus has nothing much to see. Newborns are “legally blind”; they see only objects between 4 and 30 inches (10 and 75 centimeters) away (Bornstein et al., 2005).

Soon visual experience combines with maturation of the visual cortex to im- prove visual ability. By 2 months, infants look more intently at a human face, and, tentatively and fleetingly, smile. Over time, visual scanning becomes more organ- ized and more efficient, centered on important points. Thus, 3-month-olds look more closely at the eyes and mouth, the parts of a face that contain the most infor- mation, and they much prefer photos of faces with features over photos of faces with the features blanked out (Johnson & Morton, 1991).

Binocular vision is the ability to coordinate the two eyes to see one image. Because using both eyes together is impossible in the womb, many newborns seem to focus with one eye or the other, or to use their two eyes independently, so that they momentarily look wall-eyed or cross-eyed. At about 14 weeks, binocular vision appears quite suddenly, probably because the underlying brain mechanisms are activated and the infant becomes able to focus both eyes on one thing (Atkin- son & Braddick, 2003).

Tasting, Smelling, and Touching As with vision and hearing, the senses of taste, smell, and touch function at birth and rapidly adapt to the social world. For example, one study found that a taste of sugar calmed 2-week-olds but had no effect on 4-week-olds—unless accompanied by a reassuring look from a caregiver (Zeifman et al., 1996). Another study found that sugar is a good pain reliever for newborns (Gradin et al., 2002).

binocular vision The ability to focus the two eyes in a coordinated manner in order to see one image.

Senses and Motor Skills 137

Before Leaving the Hospital As mandated by a 2004 Ohio law, 1-day-old Henry has his hearing tested via vibrations of the inner ear in response to various tones. The computer interprets the data and signals any need for more tests—as is the case for about 1 baby in 100. Normal newborns hear quite well; Henry’s hearing was fine.

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Similar adaptation occurs for the senses of smell and touch. As babies learn to recognize their caregiver’s smell and handling, they relax only when cradled by their familiar caregiver, even when their eyes are closed. The ability to be com- forted by touch is one of the important “skills” tested in the Brazelton Neonatal Assessment Scale. Although almost all newborns respond to cuddling, over time they become responsive to whose touch it is and what it communicates. For in- stance, 12-month-olds respond differently, depending on whether their mother’s touch is tense or relaxed (Hertenstein & Campos, 2001).

The entire package of early sensation seems organized for two goals: social interaction (to respond to familiar caregivers) and comfort (to be soothed amid the disturbances of infant life). Even the sense of pain and the sense of motion, which are not among the five basic senses because no body part is dedicated to them, are adapted by infants to aid both socialization and comfort.

The most important experiences are perceived with all the senses at once. Breast milk, for instance, is a mild sedative, so the newborn literally feels happier at the mother’s breast, connecting pleasure with taste, touch, smell, and sight.

Because infants respond to motion as well as to sights and sounds, many new parents soothe their baby’s distress by rocking, carrying, or even driving (with the baby in a safety seat) while humming a lullaby; here again, infant comfort is connected with social interaction. A variant of this technique is to carry the infant around the house while vacuuming the carpet: Steady noise, movement, and touch combine to soothe distress. In sum, infants’ senses are immature, but they function quite well to help babies join the human family.

Motor Skills We now come to the most visible and dramatic advances of infancy, those that ul- timately allow the child to “stand tall and walk proud.” Thanks to ongoing changes in size and proportion and to increasing brain maturation, infants markedly improve their motor skills, which are the abilities needed to move and control the body.

Reflexes Newborns can move their bodies—curl their toes, grasp with their fingers, screw up their faces—but these movements are not under voluntary control. Strictly speaking, the infant’s first motor skills are not really skills but reflexes. A reflex is an involuntary response to a particular stimulus. Newborns have dozens of

motor skill The learned ability to move some part of the body, from a large leap to a flicker of the eyelid. (The word motor here refers to movement of muscles.)

reflex A responsive movement that seems automatic because it almost always occurs in reaction to a particular stimulus. New- borns have many reflexes, some of which disappear with maturation.

138 CHAPTER 5 ■ The First Two Years: Biosocial Development

Learning About a Lime As with every other normal infant, Jacqueline’s curiosity leads to taste, then to a slow reaction, from puzzle- ment to tongue-out disgust. Jacqueline’s re- sponses demonstrate that the sense of taste is acute in infancy and that quick brain reac- tions are still to come.

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➤Response for Parents of Grown Children (from page 136): Probably not. Experience-expectant brain development is programmed to occur for all infants, requiring only the stimulation that virtually all families provide—warmth, reassuring touch, overheard conversation, facial expressions, movement. Extras such as baby talk, music, exercise, mobiles, and massage may be beneficial but are not essential.

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reflexes, 18 of which are mentioned in italics below. Three sets of reflexes are crit- ical for survival:

■ Reflexes that maintain oxygen supply. The breathing reflex begins in normal newborns even before the umbilical cord, with its supply of oxygen, is cut. Additional reflexes that maintain oxygen are reflexive hiccups and sneezes, as well as thrashing (moving the arms and legs about) to escape something that covers the face.

■ Reflexes that maintain constant body temperature. When infants are cold, they cry, shiver, and tuck in their legs close to their bodies, thereby helping to keep themselves warm. When they are hot, they try to push away blankets and then stay still.

■ Reflexes that manage feeding. The sucking reflex causes newborns to suck any- thing that touches their lips—fingers, toes, blankets, and rattles, as well as natural and artificial nipples of various textures and shapes. The rooting reflex causes babies to turn their mouths toward anything that brushes against their cheeks—a reflexive search for a nipple—and start to suck. Swallowing is an- other important reflex that aids feeding, as are crying when the stomach is empty and spitting up when too much has been swallowed too quickly.

Other reflexes are not necessary for survival but are important signs of normal brain and body functioning. Among them are the following:

■ Babinski reflex. When infants’ feet are stroked, their toes fan upward. ■ Stepping reflex. When infants are held upright with their feet touching a flat

surface, they move their legs as if to walk. ■ Swimming reflex. When they are laid horizontally on their stomachs, infants

stretch out their arms and legs. ■ Palmar grasping reflex. When something touches infants’ palms, they grip it

tightly. ■ Moro reflex. When someone startles them, perhaps by banging on the table

they are lying on, infants fling their arms outward and then bring them to- gether on their chests, as if to hold on to something, while crying with wide- open eyes.

Senses and Motor Skills 139

Never Underestimate the Power of a Reflex For developmentalists, newborn reflexes are mechanisms for survival, indicators of brain maturation, and vestiges of evolutionary his- tory. For parents, they are mostly delightful and sometimes amazing. Both of these viewpoints are demonstrated by three star performers: A 1-day-old girl stepping eagerly forward on legs too tiny to support her body; a newborn grasping so tightly that his legs dangle in space; and a newborn boy sucking peacefully on the doctor’s finger.

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fine motor skills Physical abilities involving small body movements, especially of the hands and fingers, such as drawing and picking up a coin. (The word fine here means “small.”)

Gross Motor Skills Deliberate actions coordinating many parts of the body, producing large move- ments, are called gross motor skills. These emerge directly from reflexes. Crawl- ing is one example. Newborns placed on their stomachs reflexively move their arms and legs as if they were swimming. As they gain muscle strength, they start to wiggle, attempting to move forward by pushing their arms, shoulders, and upper bodies against the surface they are lying on. Usually by 5 months or so, they be- come able to use their arms, and then legs, to inch forward on their bellies, a gross motor skill.

Between 8 and 10 months after birth, most infants can lift their midsections and crawl (or creep, as the British call it) on “all fours,” coordinating the move- ments of their hands and knees in a smooth, balanced manner (Adolph et al., 1998). Crawling is experience-dependent. Some normal babies never do it, espe- cially if they have always slept on their backs.

It is not true that babies must crawl to develop normally. All babies figure out some way to move before they can walk (inching, bear walking, scooting, creeping, or crawling); but many babies who are put to sleep on their backs (as is recom- mended, to prevent sudden death) resist “tummy time,” rolling over and fussing to indicate that they do not want crawling practice (Adolph & Berger, 2005).

Sitting also develops gradually, a matter of developing the muscles to steady the heavy top half of the body. By 3 months, babies have enough muscle control to be lap-sitters if the lap’s owner provides supportive arms. By 6 months, they can sit unsupported.

Walking progresses from reflexive, hesitant, adult-supported stepping to a smooth, coordinated gait (Bertenthal & Clifton, 1998). Some children can walk while holding on at 9 months, stand alone momentarily at 10 months, and walk well, unassisted, at 12 months. Three factors combine to allow toddlers to walk (Adolph et al., 2003):

■ Muscle strength. Newborns with skinny legs and infants buoyed by water make stepping movements, but 6-month-olds on dry land do not; their legs are too chubby for their underdeveloped muscles.

■ Brain maturation within the motor cortex. The first leg movements—kicking (alternating legs at birth and then kicking both legs together or one leg re- peatedly at about 3 months)—occur without much thought or aim. As the brain matures, deliberate leg action becomes possible.

■ Practice. Unbalanced, wide-legged, short strides become a steady, smooth gait after hours of practice.

Once the first two developments have made walking possible, infants become passionate walkers, logging those needed hours of practice. They take steps on many surfaces, with bare feet or wearing socks, slippers, or shoes. They hate to be pushed in their strollers when they can walk.

Walking infants practice keeping balance in upright stance and locomotion for more than 6 accumulated hours per day. They average between 500 and 1,500 walking steps per hour so that by the end of each day, they have taken 9,000 walking steps and traveled the length of 29 football fields.

[Adolph et al., 2003, p. 494]

Fine Motor Skills Small body movements are called fine motor skills. Hand and finger movements are fine motor skills, enabling humans to write, draw, type, tie, and so on. Move- ments of the tongue, jaw, lips, and toes are fine movements, too. Actually, mouth skills precede finger skills by many months, and skillful grabbing with the feet sometimes precedes grabbing with the hands (Adolph & Berger, 2005). However,

gross motor skills Physical abilities involving large body movements, such as walking and jumping. (The word gross here means “big.”)

140 CHAPTER 5 ■ The First Two Years: Biosocial Development

Bossa Nova Baby? This boy in Brazil demon- strates his joy at acquiring the gross motor skill of walking, which quickly becomes danc- ing whenever music plays.

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hand skills are most praised by adults. Skill at spitting or chewing is not valued as much as skill at copying a letter of the alphabet.

Regarding finger skills, newborns have a strong reflexive grasp but seem to lack hand and finger control. During their first 2 months, ba- bies excitedly stare and wave their arms at an object dangling within reach. By 3 months of age, they can usually touch it; but they cannot yet grab and hold on unless the object is placed in their hands, partly because their eye–hand coordination is too limited.

By 4 months, infants sometimes grab, but their timing is off: They close their hands too early or too late, and their grasp tends to be of short duration. Finally, by 6 months, with a concentrated, deliberate stare, most babies can reach for, grab at, and hold onto almost any object that is of the right size. They can hold a bottle, shake a rattle, and yank a sister’s braids.

Infants need not be able to see their hands to grab; they can grasp a slowly mov- ing object that is lit in an otherwise dark room (Robin et al., 1996). When the lights are on, they use vision to help with accuracy (McCarty & Ashmead, 1999).

Once reaching is possible, babies practice it enthusiastically. In fact, “from 6 to 9 months, reaching appears as a quite compulsive behaviour for small objects pre- sented within arm’s reach” (Atkinson & Braddick, 2003, p. 58).

Toward the end of the first year and throughout the second, finger skills im- prove, as babies master the pincer movement (using thumb and forefinger to pick up tiny objects) and self-feeding (first with hands, then fingers, then utensils). In the second year, grabbing becomes more selective (Atkinson & Braddick, 2003). Toddlers learn when not to pull at sister’s braids, Mommy’s earrings, and Daddy’s glasses, although, as you will learn in the next chapter, curiosity sometimes over- whelms such inhibition.

Ethnic Variations All healthy infants develop skills in the same sequence, but they vary in the age at which they acquire them. Table 5.1 shows age norms for gross motor skills, based on a large, representative, multiethnic sample of U.S. infants. When infants are grouped by ethnicity, generally African Americans are ahead of Hispanic Americans, who are ahead of European Ameri- cans. Internationally, the earliest walkers in the world are in Uganda, where well-nourished and healthy babies walk at 10 months, on average. Some of the latest walkers are in France.

What accounts for this variation? The power of genes is suggested not only by ethnic differences but also by identical twins, who begin to walk on the same day more often than fraternal twins do. Striking individual differences are appar- ent in infant strategies, effort, and concentration in mastering motor skills, again suggesting something inborn in motor-skill achievements (Thelen & Corbetta, 2002).

But genes are only a small part of most ethnic differences. Cultural patterns of child rearing can affect sensation, percep- tion, and motor skills. For instance, early reflexes are less likely to fade if culture and conditions allow extensive practice. This principle has been demonstrated with legs (the stepping reflex), hands (the grasping reflex), and crawling (the swim- ming reflex). Senses and motor skills are part of a complex and dynamic system in which practice counts (Thelen & Corbetta, 2002).

Senses and Motor Skills 141

Mind in the Making Pull, grab, look, and listen. Using every sense at once is a baby’s favorite way to experience life, generating brain connections as well as commotion.

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TABLE 5.1 At About This Time:

Age Norms (in Months) for Gross Motor Skills

When 50% When 95% of All Babies of All Babies

Skill Master the Skill Master the Skill

Sit, head steady 3 months 4 months

Sit, unsupported 6 7

Pull to stand (holding on) 9 10

Stand alone 12 14

Walk well 13 15

Walk backwards 15 17

Run 18 20

Jump up 26 29

Note: As the text explains, age norms are approximate. Mastering skills a few weeks earlier or later is not an indication of health or intelligence. Mastering them very late, however, is a cause for concern.

Source: Coovadia & Wittenberg, 2004; based primarily on Denver II (Frankenburg et al., 1992).

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For example, Jamaican caregivers provide rhythmic stretching exercises for their infants as part of daily care; their infants are among the world’s youngest walkers (Adolph & Berger, 2005). Other cultures discourage or even prevent infants from crawling or walking. The people of Bali, Indonesia, never let their infants crawl, for babies are considered divine and crawling is for animals (Diener, 2000). Similar reasoning appeared in colonial America, where “standing stools” were designed for children so they could strengthen their walking muscles without sitting or crawling (Calvert, 2003).

By contrast, the Beng people of the Ivory Coast are proud when their babies start to crawl but do not let them walk until at least 1 year. Although the Beng do not recognize the connection, one reason for this prohibition may be birth control: Beng mothers do not resume sexual relations until their baby begins walking (Gottlieb, 2000).

Although variation in the timing of the development of motor skills is normal, a pattern of slow development suggests that the infant needs careful examination. Slow infants may be retarded, ill, neglected—or perfectly fine, as I know from experience.

142 CHAPTER 5 ■ The First Two Years: Biosocial Development

The Normal Berger Babies

Cultural beliefs and the demands of daily life affect every parent and baby. When I had our first child, Bethany, I was a graduate student. I had already memorized many norms including “sitting by 6 months, walking by 12.” During her first year, Bethany reached all the developmental milestones pretty much on time. However, at 14 months, she was still not walking.

I became anxious. I read about norms with a sharper eye and learned three comforting facts:

■ Variation in timing is normal.

■ When late walking signifies brain damage, other signs of delayed development are evident. (Thankfully, Bethany was already talking.)

■ Norms for motor-skill development vary from nation to nation. (My grandmother came from France, where babies tend to walk late.)

Two months later, Bethany was walking. In my relief, I began marshaling evidence that motor skills are genetic. My students provided additional testimony to the power of genes. Those from

in person

Safe and Secure Like this Algonquin baby in Quebec, many American Indian infants still spend hours each day on a cradle board, to the distress of some non-Native adults until they see that most of the babies are quite happy that way. The discovery in the 1950s that Native American children walked at about the same age as European American children suggested that maturation, not prac- tice, led to motor skills. Later research found that most Native American infants also re- ceived special exercise sessions each day, implying that practice plays a larger role than most psychologists once thought. MI

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Public Health Measures 143

SUMMING UP

The five senses (seeing, hearing, tasting, touching, smelling) function quite well at birth, although hearing is far superior to vision, probably because of experience: The fetus has much more to hear than to see. After birth, vision develops rapidly, leading to binocular vision at about the 14th week. Quite sensitive perception from all sense organs is evident by 1 year. The senses work together and are particularly attuned to human interaction.

Motor skills begin with survival reflexes but quickly expand to include various body movements that the infant masters. Infants lift their heads, then sit, then stand, then walk and run. Sensory and motor skills follow a genetic and maturational timetable, but they are also powerfully influenced by experiences, guided by caregivers and culture, and by practice, which infants do as much as their immature and top-heavy bodies allow.

■

Public Health Measures Although precise worldwide statistics are unavailable, at least 8 billion children were born between 1950 and 2005. About 2 billion of them died before age 5. As high as this figure is, the death toll would have been twice that without advances in child care, especially such aspects of preventive care as childhood immunization, clean water, adequate nutrition, and one particular medical treatment: oral rehydra- tion therapy (giving restorative liquids to children who are sick and have diarrhea). Oral rehydration saves 3 million young children per year, almost all in developing nations, but it helps in developed nations as well (Spandorfer et al., 2005).

Jamaica, Cuba, and Barbados expected babies to walk earlier than those from Russia, China, and Korea. Many of my African American students proudly cited their sons, daughters, or younger siblings who walked at 10 months, or even 8 months, to the chagrin of their European American classmates.

Believing now in a genetic timetable for walking, I was not surprised when our second child, Rachel, took her first steps at 15 months. Our third child, Elissa, also walked “late”—though on schedule for a Berger child with some French ancestry. By then Bethany had become the fastest runner in her kindergarten.

When our fourth child, Sarah, was born, I was an established professor and author, able to afford a full-time care- giver, Mrs. Todd, from Jamaica. Mrs. Todd thought Sarah was the brightest, most advanced baby she had ever seen— except, perhaps, for her own daughter Gillian. I agreed, but I cautioned Mrs. Todd that Berger children walk late.

“She’ll be walking by a year,” Mrs. Todd told me. “Maybe sooner. Gillian walked at 10 months.”

“We’ll see,” I replied, confident in my genetic interpretation.

I underestimated Mrs. Todd. She bounced baby Sarah on her lap, day after

day. By the time Sarah was 8 months old, Mrs. Todd was already spending a good deal of time bent over, holding Sarah by both hands to practice walking—to Sarah’s great delight. Lo and be- hold, Sarah took her first step at exactly 1 year—late for a Todd baby, but amazingly early for a Berger.

As a scientist, I know that a single case proves nothing. It could be that the genetic influences on Sarah’s walking were different from those on her sisters’. Furthermore, she is only one-eighth French, a fraction I had ignored when I sought reas-

surance regarding Bethany. But in my heart I think it likely that practice, fos- tered by a caregiver with a cultural tradi- tion unlike mine, made the difference.

My Youngest at 8 Months When I look at this photo of Sarah, I see evidence of Mrs. Todd’s devotion. Sarah’s hair is washed and carefully brushed, her jumper and blouse are clean and pressed, and the carpet and stepstool are perfect equipment for stand- ing practice. Sarah’s legs—chubby and far apart—indicate that she is not about to walk early; but, given all these signs of Mrs. Todd’s attention to caregiving, it is not surprising, in hindsight, that my fourth daughter was my earliest walker.HA

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immunization A process that stimulates the body’s immune system to defend against attack by a particular contagious disease. A person may acquire immunization either naturally (by having the disease) or through vaccination (by having an injection, wear- ing a patch, swallowing, or inhaling).

Most children now live to adulthood (UNICEF, 2006). In the healthiest nations, 99.9 percent who survive the first month (when the sickest and smallest newborns sometimes die) live to age 15. Even in the least healthy nations, where a few decades ago half the children died, now about three-fourths live (see Table 5.2). Public health measures (clean water, adequate food, immunization) are the main reason childhood mortality now is much lower in most nations.

Immunization Measles, whooping cough, pneumonia, and other illnesses were once familiar childhood killers. Although these diseases can still be fatal, especially for malnour- ished children, they are no longer common in developed nations. Most children are protected because of immunization, which primes the body’s immune system to defend against a specific contagious disease. This medical development is said to have had “a greater impact on human mortality reduction and population growth than any other public health intervention besides clean water” (J. P. Baker, 2000).

When people catch a contagious disease, their immune system produces anti- bodies to prevent a recurrence. In a healthy person, a vaccine—a small dose of in- active virus (often via a “shot” in the arm)—stimulates antibodies. Some details about various vaccines are given in Table 5.3. (Immunization schedules, giving the ages at which children and adolescents should be vaccinated, appear in Appendix A, p. A-4.)

Immunization Successes Stunning successes in immunization include the following:

■ Smallpox, the most lethal disease for children in the past, was eradicated worldwide as of 1971. Vaccination against smallpox is no longer needed. Emergency workers are immunized as a precaution against bioterrorism, not a normal outbreak.

■ Polio, a crippling and sometimes fatal disease, is very rare. Widespread vacci- nation, begun in 1955, has led to the elimination of polio in most nations (in- cluding the United States). Just 784 cases worldwide were reported in 2003. In 2003, however, rumors about the safety of the polio vaccine halted immu- nization in northern Nigeria; consequently, polio reappeared in West Africa in 2004, and there were 1,948 cases worldwide in 2005 (Arita et al., 2006).

■ Measles (rubeola, not rubella) is disappearing, thanks to a vaccine developed in 1963. Prior to that time, 3 to 4 million cases were reported each year in the United States alone (CDC, 2007). In all of the Americas, fewer than 100 cases of measles occurred in 2003, down from 53,683 in 1997 (MMWR, June 13, 2003). One reason is the introduction of a new method of vaccinat- ing against measles by inhalation rather than injection, now widely used in Mexico.

■ A recent success is a newly developed vaccine against rotovirus, which now kills half a million children a year (Glass & Parashar, 2006).

Immunization protects children not only from diseases but also from serious complications, including deafness, blindness, sterility, and meningitis. Each vacci- nated child stops the spread of the disease and thus protects others. Newborns may die if they catch a disease; the fetus of a pregnant woman who contracts rubella (German measles) may be born blind, deaf, and brain-damaged; adults who contract mumps or measles become quite ill; and people who have impaired immune systems (who are HIV-positive, very old, or undergoing chemotherapy) can die from “childhood” diseases.

144 CHAPTER 5 ■ The First Two Years: Biosocial Development

TABLE 5.2

Deaths of Children Under Age 5 in Selected Countries

Number of Country Deaths per 1,000 Singapore 3*

Iceland 3*

Japan 4†

Italy 4*

Sweden 4

Spain 5†

Australia 5†

United Kingdom 6†

Canada 6

New Zealand 6†

United States 7†

Russia 18†

Vietnam 19*

China 27†

Mexico 27†

Brazil 33†

Philippines 33†

India 74†

Nigeria 194

Afghanistan 257

Sierra Leone 282

* Reduced by at least one-third since 1990. † Reduced by half since 1990. Source: UNICEF, 2006.

This table shows the number of deaths per 1,000 children under age 5 for 20 of the 192 members of the United Nations. Most nations have improved markedly on this measure since 1990. Only when war destroys families and interferes with public health measures (as it has in Afghanistan and Sierra Leone) are nations not improving.

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Public Health Measures 145

TABLE 5.3

Details About Vaccinations: United States

Year of Peak Annual 2006 Consequences of Percent of Children Known Vaccine Vaccine Introduction Disease Total Total Natural Disease Vaccinated (U.S.) Side Effects

Chicken pox 1995 4 million* 203 Encephalitis (2 in 59.4 Mild rash (1 in 20 doses) (varicella) 10,000 cases), bacterial

skin infections, shingles (300,000 per year)

DTaP 83.3 Prolonged crying, fever of 105ºF or higher (1 in 20)

Diphtheria 1923 206,939 10 Death (5 to 10 in 100 cases), muscle paralysis, heart failure

Tetanus 1927 1,560* 30 Death (30 in 100 cases), Peripheral neuritis, fractured bones, Guillain-Barré syndrome pneumonia (temporary paralysis—rare)

Pertussis 1926 (whole cell) 265,269 49 Death (2 in 1,000 cases), Brain disease (0 to 10 in 1 1991 (acellular) pneumonia (10 in 100 million doses—whole-cell

cases), seizures (1 to 2 vaccine only) in 100 cases)

H influenzae 1985 20,000* 300 Death (2 to 3 in 100 93.5 None proven (for B) cases), meningitis, (childhood) pneumonia, blood (all serotypes) poisoning, inflammation

of epiglottis, skin or bone infections

MMR 91.5 Fever of 103°F or higher (5 to 15 in 100 doses)

Measles 1963 894,134 734 Encephalitis (1 in 1,000 cases), pneumonia (6 in 100 cases), death (1 to 2 in 1,000 cases), seizure (6 to 7 in 1,000 cases)

Mumps 1967 152,209 6,358 Deafness (1 in 20,000 cases), inflamed testicles (20 to 50 in 100 postpubertal males)

Rubella 1969 56,686 8 Blindness, deafness, Temporary joint pain (25 heart defects, and/or in 100 adult doses in retardation in 85 percent women) of children born to mothers infected in early pregnancy

Pneumococcus† 2000 93,000* 15 Death or serious illness Fever over 100.3°F (childhood) caused by meningitis, (22 in 100 doses)

pneumonia, blood poisoning, ear infections

Polio 1955 21,269 0 Death (2 to 5 in 100 89.6 Vaccine-induced polio (paralytic) cases in children), (oral vaccine only—1 in

respiratory failure, 2.4 million doses) paralysis, postpolio syndrome

*Estimated. †Lieu et al., 2000. Source: MMWR, January 12, 2007.

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Problems with Immunization Parents do not notice if their child does not get seriously ill. One doctor, who wants people to attend to disease prevention, laments, “No one notices when things go right” (Bortz, 2005, p. 389). Unfortunately, “minor” diseases can kill. One Kansas father, age 36, caught varicella (chicken pox) from his 9-year-old daughter. He suffered numerous complications and died on March 9, 2002 (MMWR, June 13, 2003). No one in his family had been vaccinated (Kansas did not require varicella immunization for school entry). The 9-year-old was the carrier, but the parents, school, pediatrician, and lawmakers were also part of the problem. Before the vac- cine, more than 100 people in the United States died each year from chicken pox and 1 million were itchy and feverish for a week. Fortunately, the death and disease rates have been dramatically reduced (Nguyen et al., 2005).

Many parents are concerned about potential side effects of vaccinations. However, the risks of the diseases are far greater than the risks from immuniza- tion (as Table 5.3 indicates). A review of the published research concludes: “The data demonstrate consistently that the overall benefit of vaccinations ranks among the foremost achievements in modern public health” (Dershewitz, 2002). A hypothesis that the MMR (measles-mumps-rubella) vaccine causes autism has been repeatedly disproved (Shattuck, 2006).

More than 1 million children in developing nations die each year because effective vaccines against AIDS, malaria, cholera, typhoid, and shigellosis are not yet ready for widespread use (Russell, 2002). Another 2 to 3 million die each year from diphtheria, tetanus, and measles because they have not been immunized (Mahmoud, 2004); 100,000 children in India died in 2005 from measles alone (Duggar, 2006). Even in the United States, although most 2-year-olds are fully immunized, only one-third get all their vaccinations on time, with no unneeded extras (Mell et al., 2005).

Sudden Infant Death Syndrome Infant mortality worldwide has plummeted in recent years (see Figure 5.5). Several reasons have already been mentioned: advances in newborn care, better nutrition, access to clean water, and widespread immunization. Another reason is that fewer babies are dying of unknown causes, especially sudden infant death syndrome (SIDS).

sudden infant death syndrome (SIDS) A situation in which a seemingly healthy infant, at least 2 months of age, suddenly stops breathing and dies unexpectedly while asleep. The cause is unknown, but it is correlated with sleeping on the stomach and having parents who smoke.

146 CHAPTER 5 ■ The First Two Years: Biosocial Development

Look Away! The benefits of immunization justify the baby’s brief discomfort, but many parents still do not appreciate the importance of following the recommended schedule of immunizations. STE

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Especially for Nurses and Pediatricians A mother refuses to have her baby immunized because she wants to prevent side effects. She wants your signature for a religious exemption. What should you do?

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Still, some young infants who appear healthy—already gaining weight, learning to shake a rattle, starting to roll over, and smiling at their caregivers—die unex- pectedly in their sleep. If autopsy and careful investigation find no apparent cause of death, the diagnosis is SIDS (Byard, 2004).

In 1990 in the United States, about 5,000 babies died of SIDS, about 1 infant in 800. Canada, Great Britain, Australia, and virtually every European and South American nation experienced a similar rate. Today, that rate has been cut in half, primarily because fewer infants are put to sleep on their stomachs and because fewer mothers smoke cigarettes. The first of these preventive measures has arisen from an increased awareness of and a greater respect for cultural differences.

Within ethnically diverse nations such as the United States, Canada, Great Britain, Australia, and New Zealand, babies of Asian descent have always been far less likely than babies of European or African de- scent to succumb to SIDS (Byard, 2004). Although low socioeconomic status (SES) is also a risk factor for SIDS, poverty does not seem to be the primary explanation for this ethnic difference. For example, Bangladeshi infants in England tend to be from low-SES families, yet they are much less vulnerable to SIDS than are traditional British in- fants from middle-class families. For decades, pediatricians thought that genes were the underlying cause.

Fortunately, awareness of the impact of culture led to examination of infant-care routines. Bangladeshi infants are usually breast-fed, and when they sleep, they are surrounded by family members in a rich sen- sory environment, hearing noises and feeling the touch of their care- givers. They do not sleep deeply for very long. By contrast, their traditional British age-mates tend to sleep in their own private spaces, and these “long periods of lone sleep may contribute to the higher rates of SIDS among white infants” (Gantley et al., 1993).

Similarly, infants of Chinese heritage rarely die of SIDS (Beal & Porter, 1991). In fact, before a worldwide campaign to reduce the risk, only 1 baby in 3,000 in Hong Kong died of SIDS, compared with 1 baby in 200 in New Zealand (Byard, 2004). Why? First, Chinese parents tend to their babies periodically as the infants sleep, caressing a cheek

Public Health Measures 147

Sleeping Like a Baby It’s best to lay babies on their backs to sleep—even if it’s in a ham- mock in a Cambodian temple.

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Sources: National Center for Health Statistics, 2000; U.S. Census Bureau, 2006.

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70 60

80 90

110 100

140

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India Chile Mexico Poland United States

Deaths before age 1 per 1,000 newborns

Infant Mortality Rates: 1970 and 2005

1970 2005

FIGURE 5.5

More Babies Are Surviving Improvements in public health—better nutrition, cleaner water, more widespread immunization—over the past three decades have meant millions of survivors.

Critical Thinking Question (see answer, page 150): The United States seems to be doing very well on reducing infant deaths. Can you suggest another way to present the U.S. data that would lead to another impression?

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or repositioning a limb. Second, almost all Chinese infants are breast-fed. This makes them sleep less soundly, and deep sleep is a factor in SIDS. (Cow’s milk is harder to digest, so it causes tiredness and thus a deeper sleep.) And third, Chinese parents put their infants to sleep on their backs. This is crucial, as the following explains.

Especially for Police Officers and Social Workers If an infant died suddenly, what would you look for to distinguish SIDS from homicide?

148 CHAPTER 5 ■ The First Two Years: Biosocial Development

Back to Sleep

When pediatricians, nurses, and anthropologists observed in- fant care among Asians and Europeans, they noticed a crucial difference: sleeping position. In all the ethnic groups with a low incidence of SIDS, babies were put to sleep on their backs; in all those with high rates, babies slept on their stomachs. The ex- pressed reasons varied. For example, until recently, Benjamin Spock’s book of advice for parents (more than 30 million copies sold) recommended stomach sleeping:

There are two disadvantages to babies sleeping on their back. If they vomit, they’re more likely to choke. Also, they tend to keep the head turned toward the same side, usually toward the center of the room. This may flatten that side of the head. It won’t hurt the brain, and the head will gradually straighten out, but it may take a couple of years.

[Spock, 1976, p. 199]

Contrary advice was provided to Turkish mothers, who were told: “Never put a swaddled baby to sleep on its stomach, for it would not be able to breathe. Instead, put the baby down to sleep on its back” (Delaney, 2000, p. 131).

Both these experts were mistaken: Babies sleeping on their stomachs can breathe, and babies sleeping on their backs do not choke. Neither expert realized the connection between SIDS and sleeping position.

As a new mother, I remember reading these chilling words: “Every once in a while, a baby between the ages of 3 weeks and 7 months is found dead in bed. There is never an adequate explanation, even when a postmortem examination is done” (Spock, 1976, pp. 576–577). I put my babies to sleep on their

stomachs, as my mother did with me and as the hospital where they were born did with thousands of newborns every year. My infants survived, but I know parents whose babies did not.

About two decades ago, researchers in Australia advised a group of non-Asian mothers to put their infants to sleep on their backs. Other scientists in other nations tried the same experi- ment. The results were dramatic: Fewer infants died. For exam- ple, one comparison study found that the risk of SIDS was only one-fourth as high when infants slept supine (on their backs) instead of prone (Ponsonby et al., 1993).

It is now accepted that “back to sleep” (as the public-awareness slogan puts it) is safest. Worldwide, SIDS rates have fallen—to 1 in 1,000 in New Zealand, for instance. In the United States, in the four years between 1992 and 1996, the stomach-sleeping rate decreased from 70 to 24 percent, and the SIDS rate dropped from 1.2 to 0.7 per 1,000, a “remarkable success” (Pollack & Frohna, 2001).

Sleeping position does not prevent all SIDS deaths. Low birthweight, overdressed infants, and teenage parenthood are risk factors (Byard, 2004). Maternal smoking is particularly risky (Anderson et al., 2005). Both breast-feeding and pacifier use are protective (Li et al., 2006), perhaps because they strengthen in- fants’ breathing reflexes. Recently, it has been discovered that the existence of too many serotonin receptors in the brain stem, which controls heart rate and breathing, may be a major risk fac- tor for SIDS (Paterson et al., 2006). Infants with this condition do not automatically rouse themselves to breathe when their blood oxygen falls, and death sometimes results. Unfortunately, this abnormality becomes apparent only upon autopsy.

issues and applications

Nutrition Indirectly, nutrition has been a theme throughout this chapter. You read that pedi- atricians closely monitor early weight gain, that head-sparing protects the brain from temporary undernourishment, that oral rehydration prevents childhood diar- rhea from being fatal. Now, we focus directly on how infants are fed.

Breast Is Best For most newborns, good nutrition starts with mother’s milk. First comes colostrum, a thick, high-calorie fluid secreted by the woman’s breasts at the birth of her child. After about three days, the breasts begin to produce milk, which is the ideal infant

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food (see Table 5.4). Mother’s milk helps prevent almost every infant illness and allergy (Isolauri et al., 1998). It is always sterile and at body temperature; it con- tains more iron, vitamins C and A, and many other nourishing substances than cow’s or goat’s milk.

Babies who are exclusively breast-fed are less likely to get sick. This is true in infancy because breast milk provides antibodies against any disease to which the mother has natural or acquired immunity. Breast-feeding also decreases the risk of diseases that appear in childhood and adulthood, among them asthma, obesity, and heart disease (Oddy, 2004).

The specific fats and sugars in breast milk make it more digestible, and proba- bly better for the infant brain, than any prepared formula (Riordan, 2005). The particular composition of breast milk adjusts to the age of the baby, with breast milk for premature babies distinct from breast milk for older infants.

Quantity increases to meet the demand: Twins and even triplets can grow strong while being exclusively breast-fed for months. In fact, breast milk appears to have so many advantages over formula that critics question the validity of the research: Although studies control for education and income, it is possible that women who choose to breast-feed are better caregivers in some ways not affected by SES. In the United States, a survey finds that parents of breast-fed babies are more likely to be married, college graduates, or immigrants (Gibson-Davis & Brooks-Gunn, 2006; see Research Design).

Bottle-feeding may be better than breast-feeding in unusual circumstances, such as when the mother is HIV-positive or uses toxic or addictive drugs. Even then, however, breast milk may be best. In Africa, HIV-positive women are en- couraged to breast-feed because their infants’ risk of catching the virus is less than their risk of dying from infections, diarrhea, or malnutrition as a result of improper bottle-feeding. Formula is recommended only if it is “acceptable, feasible, afford- able, sustainable, and safe” (WHO, 2000).

Virtually all doctors worldwide recommend exclusive breast-feeding for the first four to six months. Then other foods can be added—especially cereals and bananas,

Public Health Measures 149

Research Design Scientists: Christina Gibson-Davis and Jeanne Brooks-Gunn.

Publication: American Journal of Public Health (2006).

Participants: A study called Fragile Fami- lies surveyed about 5,000 new mothers from 75 U.S. hospitals.

Design: Mothers and fathers were asked about their social status (e.g., education, marriage, immigration, income, employ- ment) and breast-feeding, with assur- ance of confidentiality. Questions were asked of both parents soon after birth and again of the mothers a year later.

Major conclusion: A mother’s decision to start and continue breast-feeding is affected by many aspects of her social context. U.S.-born mothers are espe- cially less likely to breast-feed.

Comment:This finding is for a popula- tion often omitted from other surveys. Confirmation that education and mar- riage are significant correlates of breast- feeding suggests that husbands and greater exposure to education promote breast-feeding.

The Same Event, A Thousand Miles Apart: Breast-Feeding Breast-feeding is universal. None of us would have existed if our foremothers had not successfully breast-fed their babies for millennia. Currently breast-feeding is practiced worldwide, but it is no longer the only way to feed infants, and each culture has particular practices.

➤Response for Nurses and Pediatricians (from page 146): It is very difficult to convince people that their method of child rearing is wrong, although, given what you know, you should try. In this case, listen respectfully and then describe specific instances of serious illness or death from a childhood disease. Suggest that the mother ask her grandparents if they knew anyone who had polio, tuber- culosis, or tetanus (they probably did). If you cannot convince this mother, do not despair: Vaccination of 95 percent of toddlers protects the other 5 percent. If the mother has deeply held religious reasons, talk to her clergy adviser, if not to change the mother’s mind, at least to understand her perspective.

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Observation Quiz (see answer, page 153): What three differences do you see between these two breast-feeding women—one in the United States and one in Madagascar?

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which are easily digested and provide the iron and vitamin C that older infants need. Breast milk should be part of the diet for a year (longer if mother and baby wish). Babies who do not get enough sunlight may need additional vitamin D— whether through supplemental drops or pills or cereal and milk—to prevent rickets (Stokstad, 2003).

In developing nations, breast-feeding dramati- cally reduces infant death. In the United States and worldwide, more than 90 percent of infants are breast-fed at birth, but only 36 percent are ex- clusively breast-fed for the first six months. Rates are slightly lower for the least developed nations. By their second birthday, half of the world’s in- fants (especially in poor nations) are still being fed some breast milk, usually at night (UNICEF, 2006).

Whether or not a breast-feeding mother con- tinues to breast-feed for 6 months depends a great deal on her experiences in the first week, when encouragement and practical help are most needed (DiGirolamo et al., 2005). Ideally, nurses visit new mothers at home for several weeks; such visits also increase the likelihood that breast-feed- ing will continue (Coutinbo et al., 2005).

Malnutrition Protein-calorie malnutrition occurs when a person does not consume sufficient food of any kind. Roughly 9 percent of the world’s children suffer from “wasting,” being severely and chroni-

cally malnourished because they do not get adequate calories and protein (UNICEF, 2006). These 9 percent are very short for their age and underweight for their height. Many more children are too short or too underweight (2 or more stan- dard deviations below the average well-nourished child). According to this crite- rion, between 25 and 30 percent of the world’s children are malnourished (UNICEF, 2006).

To measure a particular child’s nutritional status, compare weight and height with the detailed norms presented in Appendix A, pages A-6 and A-7. A child may simply be genetically short or thin, but a decline in percentile ranking during the first two years is an ominous sign. Birthweight should triple by age 1, and the 1-year-old’s legs and cheeks should be chubby with baby fat (which disappears over the next several years).

Chronically malnourished infants and children suffer in three ways:

■ Their brains may not develop normally. If malnutrition has continued long enough to affect the baby’s height, it may also have affected the brain (Grantham-McGregor & Ani, 2001).

■ Malnourished children have no body reserves to protect them against com- mon diseases. About half of all childhood deaths occur because malnutrition makes a childhood disease lethal.

■ Some diseases result directly from malnutrition.

protein-calorie malnutrition A condition in which a person does not consume suffi- cient food of any kind. This deprivation can result in several illnesses, severe weight loss, and sometimes death.

150 CHAPTER 5 ■ The First Two Years: Biosocial Development

TABLE 5.4

The Benefits of Breast-Feeding

For the Baby Balance of nutrition (fat, protein, etc.) adjusts to age of baby

Breast milk has micronutrients not found in formula

Less infant illness: including allergies, ear infections, stomach upsets

Less childhood asthma

Better childhood vision

Less adult illness, including diabetes, cancer, heart disease

Protection against measles and all other childhood diseases, since breast milk contains antibodies

Stronger jaws, fewer cavities, advanced breathing reflexes (less SIDS)

Higher IQ, less likely to drop out of school, more likely to attend college

Later puberty, less prone to teenage pregnancy

Less likely to become obese

For the Mother Easier bonding with baby

Reduced risk of breast cancer and osteoporosis

Natural contraception (with exclusive breast-feeding, for several months)

Pleasure of breast stimulation

Satisfaction of meeting infant’s basic need

No formula to prepare; no sterilization needed

Easier to travel with the baby

For the Family Increased survival of other children (because of spacing of births)

Increased family income (because both formula and medical care are expensive)

Less stress on father, especially at night (he cannot be expected to feed the baby)

Sources: DiGirolamo et al., 2005; Oddy, 2004; Riordan, 2005.

➤Answer to Critical Thinking Question (from page 147): The same data could be presented in terms of rate of reduction in infant mortality. Chile’s rate in 2005 was only 10 percent of what it had been in 1970— much better than the U.S. rate, which in 2005 was 35 percent of what it had been in 1970. (Other data show that about 25 developed nations have lower infant mortality rates than the United States.)

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The worst disease directly caused by malnutrition is marasmus. Growth stops, body tissues waste away, and the infant victim eventually dies. Prevention of marasmus begins long before birth, with good nutrition for the pregnant woman. Then breast-feeding on demand (eight or more times a day) and frequent check- ups to monitor the baby’s weight can stop marasmus before it begins. Infants who show signs of “failure to thrive” (they do not gain weight) can be hospitalized and treated before brain damage occurs.

Malnutrition after age 1 may cause kwashiorkor. Ironically, kwashiorkor means “a disease of the older child when a new baby arrives”—signifying cessation of breast-feeding and less maternal attention. In kwashiorkor, the child’s growth is retarded; the liver is damaged; the immune system is weakened; the face, legs, and abdomen swell with fluid (edema); the energy level is reduced (malnourished children play less); and the hair becomes thin, brittle, and colorless.

SUMMING UP

Many public health practices save millions of infants each year. Immunizing children, putting infants to sleep on their backs, and breast-feeding are simple yet life-saving steps. These are called “public health” measures rather than parental practices because they are affected by culture and national policies.

An underlying theme of this chapter is that healthy biological growth is the result not simply of genes and nutrition but also of a social environment that provides opportuni- ties for growth: lullabies and mobiles for stimulating the infant’s senses, encourage- ment for developing the first motor skills, and protection against disease. Each aspect of development is linked to every other aspect, and each developing person is linked to family, community, and world.

■

Public Health Measures 151

The Same Event, A Thousand Miles Apart: Children Still Malnourished Infant malnutrition is common in nations at war (like Afghanistan, at right) or with crop failure (like Niger, at left ). UNICEF relief programs reach only half the children in either nation. The children in these photographs are among the lucky ones.

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marasmus A disease of severe protein- calorie malnutrition during early infancy, in which growth stops, body tissues waste away, and the infant eventually dies.

kwashiorkor A disease of chronic malnutri- tion during childhood, in which a protein deficiency makes the child more vulnera- ble to other diseases, such as measles, diarrhea, and influenza.

➤Response for Police Officers and Social Workers (from page 148): An autopsy, or at least a speedy and careful examination by a medical pathologist, is needed. Suspected foul play must be either substantiated or firmly rejected—so that the parents can be arrested or warned about conditions that caused an accident, or can mourn in peace. Careful notes about the immediate circumstances—such as the infant’s body position when discovered, the position of the mattress and blankets, the warmth and humidity of the room, and the baby’s health—are crucial. Further, although SIDS victims sometimes turn blue and seem bruised, they rarely display signs of specific injury or neglect, such as a broken limb, a scarred face, an angry rash, or a skinny body.

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152 CHAPTER 5 ■ The First Two Years: Biosocial Development

Body Changes 1. In the first two years of life, infants grow taller, gain weight, and increase in head circumference—all indicative of develop- ment. The norm at birth is 71⁄2 pounds in weight, 20 inches long (about 3,400 grams, 51 centimeters). Birthweight doubles by 4 months, triples by 1 year, and quadruples by 2 years, when tod- dlers weigh about 30 pounds (131⁄2 kilograms).

2. Sleep gradually decreases over the first two years. As with all areas of development, variations in sleep patterns are normal, caused by both nature and nurture. Co-sleeping is increasingly common for very young infants, and many developmentalists con- sider it a harmless, or even beneficial, practice.

Brain Development 3. The brain increases dramatically in size, from about 25 to 75 percent of adult weight, in the first two years. Complexity in- creases as well, with transient exuberance of cell growth, develop- ment of dendrites, and formation of synapses. Both growth and pruning aid cognition.

4. Experience is vital for dendrites and synapses to link neurons. In the first year, parts of the cortex dedicated to the senses and motor skills mature. If neurons are unused, they atrophy, and the brain regions are rededicated to other sensations. Normal stimu- lation, which almost all infants obtain, allows experience-expectant maturation.

5. Most experience-dependent brain growth reflects the varied, culture-specific experiences of the infant. Therefore, one person’s brain differs from another’s. However, all normal infants are equally capable in the basic ways—emotional, linguistic, and sensory— that humans share.

Senses and Motor Skills 6. At birth, the senses already respond to stimuli. Prenatal expe- rience makes hearing the most mature sense and vision the least mature sense. Vision improves quickly. Infants use their senses to strengthen their early social interactions.

7. Newborns have many reflexes, including the survival reflexes of sucking and breathing. Gross motor skills are soon evident, from rolling over to sitting up (at about 6 months), from standing to walking (at about 1 year), from climbing to running (before age 2).

8. Fine motor skills are difficult for infants, but babies gradually develop the hand and finger control needed to grab, aim, and ma- nipulate almost anything within reach. Experience, time, and mo- tivation allow infants to advance in all their motor skills.

Public Health Measures 9. About 2 billion infant deaths have been prevented in the past half-century because of improved health care. One major innova- tion is immunization, which has eradicated smallpox and virtually eliminated polio and measles in developed nations.

10. Sudden infant death syndrome (SIDS) once killed about 5,000 infants per year in the United States and thousands more worldwide. This number has been reduced by half since 1990, primarily because researchers discovered that putting infants to sleep on their backs makes SIDS less likely. If mothers stopped smoking, hundreds more infants would survive.

11. Breast-feeding is best for infants, partly because breast milk reduces disease and promotes growth of every kind. Most babies are breast-fed at birth, but less than half are exclusively breast-fed for 6 months, as most doctors worldwide recommend.

12. Severe malnutrition stunts growth and can cause death, di- rectly through marasmus or kwashiorkor and indirectly through vulnerability if a child catches measles, an intestinal disorder, or other illness.

norm (p. 126) percentile (p. 126) head-sparing (p. 127) REM sleep (p. 127) co-sleeping (p. 128) neuron (p. 129) cortex (p. 129) axon (p. 130)

dendrite (p. 130) synapse (p. 130) transient exuberance (p. 131) experience-expectant (p. 132) experience-dependent (p. 132) prefrontal cortex (p. 133) shaken baby syndrome (p. 133) self-righting (p. 134)

sensitive period (p. 134) sensation (p. 136) perception (p. 136) binocular vision (p. 137) motor skill (p. 138) reflex (p. 138) gross motor skills (p. 140) fine motor skills (p. 140)

immunization (p. 144) sudden infant death syndrome

(SIDS) (p. 146) protein-calorie malnutrition

(p. 150) marasmus (p. 151) kwashiorkor (p. 151)

SUMMARY

KEY TERMS

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Summary 153

7. Why would parents encourage early (before 12 months) or late (after 12 months) walking?

8. In what ways does immunization save lives?

9. What are the signs of malnutrition?

10. Since breast-feeding is best, why do most North American mothers bottle-feed their 6-month-olds?

11. When is it better not to breast-feed an infant?

1. In what aspects of development (at any age) would it be best to be at the 10th, 50th, and 90th percentiles? Give an example for each.

2. How might stress hormones affect later development?

3. Why is pruning an essential part of brain development?

4. What is the relationship between the cortex and the dendrites?

5. What are the differences in the visual abilities of a newborn and a 3-month-old?

6. What characteristics of the human brain seem designed for hearing and understanding speech?

the caregiver how old the infant is. (Most caregivers know the in- fant’s exact age and are happy to tell you.)

3. This project can be done alone, but it is more informative if sev- eral students pool responses. Ask 3 to 10 adults whether they were bottle-fed or breast-fed and, if breast-fed, for how long. If anyone does not know, or if anyone expresses embarrassment about how long they were breast-fed, that itself is worth noting. Is there any correlation between adult body size and mode of infant feeding?

1. Immunization regulations and practices vary, partly for social and political reasons. Ask at least two faculty or administrative staff members what immunizations students at your college must have and why. If you hear “it’s a law,” ask why that law is in place.

2. Observe three infants (whom you do not know) in public places such as a store, playground, or bus. Look closely at body size and motor skills, especially how much control each baby has over legs and hands. From that, estimate the age in months, and then ask

KEY QUESTIONS

APPLICATIONS

➤Answer to Observation Quiz (from page 149): The babies’ ages, the settings, and the mothers’ apparent attitudes. The U.S. mother (left) is in a hospital indoors and seems attentive to whether she is feeding her infant the right way. The mother in Madagascar (right) seems confident and content as she feeds her older baby in a public place, enjoying the social scene.

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The First Two Years: Cognitive Development

This chapter is about infant cognition, a word that means “thinking”in a very broad sense, including language, learning, memory, andintelligence in the first two years of life. My aunt’s husband, UncleHenry, boasted that he did nothing with his three children until they were smart enough to talk. He may have found a good excuse to avoid diapering, burping, and bathing, but his beliefs about cognition were wrong. Babies are smart from the first days of life, and they communicate quite well long before they begin talking. Uncle Henry missed his children’s most im- pressive cognitive accomplishments.

Infants strive to organize sensations and perceptions and to understand sequence and direction, the familiar and the strange, objects and people, events and experiences, permanence and transiency, cause and effect. By the end of the first year—often much sooner—babies have succeeded at all these. They have goals and know how to reach them. By the end of the sec- ond year, they speak in sentences, think before acting, and pretend to be someone or something (a mother, an airplane) that they know they are not. Smart? Yes.

We begin this chapter by looking at Piaget’s framework for observing this amazing intellectual progression, from newborns who know nothing to tod- dlers who can make a wish, say it out loud, and blow out their birthday can- dles. We end by asking how cognitive accomplishments, particularly the acquisition of language, occur.

Sensorimotor Intelligence As you learned in Chapter 2, Jean Piaget was a Swiss scientist, born in 1896. He was “arguably the most influential researcher of all times within the area of cognitive developmental psychology” (Birney et al., 2005, p. 328). Contrary to the popular ideas of his day (including those of my Uncle Henry), Piaget realized that infants are smart and active learners, adapting to experience. And adaptation, according to Piaget, is the essence of intelligence.

Piaget described four distinct periods of cognitive development. The first period begins at birth and ends at about 24 months. Piaget called it sensori- motor intelligence because infants learn through their senses and motor skills. This two-year-long period is subdivided into six stages (see Table 6.1).

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CHAPTER OUTLINE

� Sensorimotor Intelligence

Stages One and Two: Primary Circular Reactions

Stages Three and Four: Secondary Circular Reactions

THINKING LIKE A SCIENTIST: Object Permanence Revisited

Stages Five and Six: Tertiary Circular Reactions

Piaget and Research Methods

� Information Processing

Affordances Memory

� Language: What Develops in the First Two Years?

The Universal Sequence The Naming Explosion Theories of Language Learning

sensorimotor intelligence Piaget’s term for the way infants think—by using their senses and motor skills—during the first period of cognitive development.

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Stages One and Two: Primary Circular Reactions In every aspect of sensorimotor intelligence, there is an active (not passive) inter- action between the brain and the senses. Sensation, perception, and cognition cycle back and forth (circling round and round) in what Piaget calls a circular re- action. The first two stages of sensorimotor intelligence are examples of primary circular reactions, which are reactions that involve the infant’s own body.

Stage one, called the stage of reflexes, lasts only for a month. It includes senses as well as reflexes, which are the foundation of infant thought. Reflexes become de- liberate movements; sensation leads into perception and then cognition. Sensori- motor intelligence begins.

As reflexes adjust, the baby enters stage two, first acquired adaptations (also called the stage of first habits). Adaptation is crucial to learning, as it includes both assimilation and accom- modation (see p. 45), which the person uses to make sense of experience. This adaptation from reflexes to deliberate action occurs because repeated responses provide information about what the body does and how that action feels.

As an example, newborns suck anything that touches their lips; sucking is one of the strongest reflexes. By about 1 month, infants start to adapt sucking. Some items require not just assimilation but accommodation: Pacifiers need to be sucked without the reflexive tongue-pushing and swallowing that other nipples require. This adaptation is a sign that infants have begun to interpret their perceptions; as they accommo- date to pacifiers, they are “thinking.”

primary circular reactions The first of three types of feedback loops in sensorimotor intelligence, this one involving the infant’s own body. The infant senses motion, suck- ing, noise, and so on, and tries to understand them.

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TABLE 6.1

The Six Stages of Sensorimotor Intelligence

For an overview of the stages of sensorimotor thought, it helps to group the six stages into pairs. The first two stages involve the infant’s responses to its own body.

Primary Circular Reactions Stage One (birth to 1 month)

Stage Two (1–4 months)

Stage Three (4–8 months)

Stage Four (8–12 months)

Stage Five (12–18 months)

Stage Six (18–24 months)

Reflexes: sucking, grasping, staring, listening.

The first acquired adaptations: accommodation and coordination of reflexes. Examples: sucking a pacifier differently from a nipple; grabbing a bottle to suck it.

An awareness of things: responding to people and objects. Example: clapping hands when mother says “patty-cake.”

New adaptation and anticipation: becoming more deliberate and purposeful in responding to people and objects. Example: putting mother’s hands together in order to make her start playing patty-cake.

New means through active experimentation: experimentation and creativity in the actions of the “little scientist.” Example: putting a teddy bear in the toilet and flushing it.

New means through mental combinations: considering before doing provides the child with new ways of achieving a goal without resorting to trial-and-error experiments. Example: before flushing, remembering that the toilet overflowed the last time, and hesitating.

The next two stages involve the infant’s responses to objects and people.

Secondary Circular Reactions

The last two stages are the most creative, first with action and then with ideas.

Tertiary Circular Reactions

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Time for Adaptation Sucking is a reflex at first, but adaptation begins as soon as an in- fant differentiates a pacifier from her mother’s breast or realizes that her hand has grown too big to fit into her mouth. This infant’s expres- sion of concentration suggests that she is about to make that adaptation and suck just her thumb from now on.

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In other words, adaptation in the early weeks relies primarily on reflexive assim- ilation: Everything suckable is assimilated as worthy of being sucked until accom- modation occurs. After several more months, more adaptation of the sucking reflex is evident. The infant’s cognitive responses include: Suck some things to soothe hunger, suck some for comfort, and never suck others (fuzzy blankets, large balls).

Adaptation is apparent when babies are not hungry but want the reassurance of rhythmic sucking. Then they suck a pacifier, or, if their reflexes have not adapted to a pacifier (because one was not offered), they suck thumbs, fingers, or knuckles.

Stages Three and Four: Secondary Circular Reactions In stages three and four, development switches from primary circular reactions, involving the baby’s own body (stages one and two), to secondary circular reac- tions, involving the baby and a toy or another person.

During stage three (age 4 to 8 months), infants interact diligently with people and things to produce exciting experiences, making interesting events last. Realizing that rattles make noise, for example, they wave their arms and laugh whenever someone puts a rattle in their hand. The sight of something that normally delights an infant—a favorite toy, a smiling parent—can trigger active efforts for interaction.

Stage four (8 months to 1 year) is called new adaptation and anticipation, or “the means to the end,” because babies now think about a goal and begin to un- derstand how to reach it. Thinking is more innovative in stage four than it was in stage three because adaptation is more complex. For instance, instead of always smiling at Daddy, an infant might assess Daddy’s mood first. Stage-three babies merely understand how to continue an experience. Stage-four babies anticipate.

A 10-month-old girl who enjoys playing in the bathtub might see a bar of soap, crawl over to her mother with it as a signal to start her bath, and then remove her clothes to make her wishes crystal clear—finally squealing with delight when the bath water is turned on. Similarly, if a 10-month-old boy sees his mother putting on her coat to leave, he might try to stop her or drag over his own jacket to signal that he wants to go, too.

These examples reveal goal-directed behavior—that is, purposeful action. The baby’s obvious goal-directedness stems from an enhanced awareness of cause and effect, as well as from better memory for actions already completed and better

secondary circular reactions The second of three types of feedback loops in sensori- motor intelligence, this one involving people and objects. The infant is respon- sive to other people and to toys and other objects the infant can touch and move.

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Talk to Me This 4-month-old is learning how to make interesting sights last: The best way to get Daddy to respond is to vocalize, stare, smile, and pat his cheek.

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Especially for Parents When should parents decide whether to feed their baby only by breast, only by bottle, or using some combination? When should they decide whether or not to let their baby use a pacifier?

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understanding of other people’s intentions (Behne et al., 2005; Willatts, 1999). Cognitive awareness coincides with the emergence of the motor skills (e.g., crawl- ing, walking) needed to achieve goals; both developments are the result of neuro- logical maturation (Adolph & Berger, 2006).

Piaget thought that the concept of object permanence emerges at about 8 months. Object permanence refers to the awareness that objects or people con- tinue to exist when they are no longer in sight. Other researchers agreed that a goal- directed search for toys that have fallen from the baby’s crib, rolled under a couch, or disappeared under a blanket does not begin to emerge until about 8 months, just as Piaget indicated. However, many current scientists question Piaget’s interpreta- tions, as the following explains.

object permanence The realization that objects (including people) still exist when they cannot be seen, touched, or heard.

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thinking like a scientist Object Permanence Revisited

Before Piaget, it was assumed that infants understood objects just as adults do. Piaget demonstrated with a simple experiment that that assumption was wrong. An adult shows an infant an interesting toy, covers it with a lightweight cloth, and observes the infant’s response. The results:

■ Infants younger than 8 months do not search (by removing the cloth).

■ At about 8 months, infants search immediately after the object is covered but seem to forget about the object if they have to wait a few seconds.

■ By 2 years, children seem to understand object perma- nence: They search well but not perfectly. Imperfection is evident when playing hide-and-seek: Preschoolers may fear that someone has really disappeared, or they may hide in obvious places (such as behind a coat rack with their feet still visible or as a big lump under a sheet on a bed).

As you learned in Chapter 1, thinking like a scientist means: (1) replication (thousands of scientists in dozens of nations have done this with Piaget’s original research design) and (2) question- ing the conclusions. Piaget claimed that failure to search for a

hidden object meant that infants have no concept of object per- manence. Other researchers ask whether other immaturities, such as imperfect motor skills or fragile memory, could mask an infant’s understanding that objects still exist when they are no longer visible (Cohen & Cashon, 2006; Ruffman et al., 2005).

Apparently they can. As one researcher points out, “Amid his acute observation and brilliant theorizing, Piaget . . . mistook infants’ motor incompetence for conceptual incompetence” (Mandler, 2004, p. 17). A series of clever experiments, in which objects seemed to disappear behind a screen while researchers traced eye movements and brain activity, revealed some inkling of object permanence in infants as young as 41⁄2 months (Baillargeon & DeVos, 1991; Spelke, 1993).

The specific finding that contradicted Piaget is that, long before 8 months, infants showed surprise (by staring longer, for instance) when an object they saw was hidden by a screen and

Peek-a-Boo The best hidden object is Mom under an easily moved blanket, as 7-month-old Elias has discovered. Peek-a-boo is fun from about 7 to 12 months. In another month, Elias will search for more conventionally hidden objects. In a year or two, his surprise and delight at finding Mom will fade.

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tertiary circular reactions The third of three types of feedback loops in sensorimotor intelligence, this one involving active exploration and experimentation. The infant explores a range of new activities, varying his or her responses as a way of learning about the world.

“little scientist” Piaget’s term for the stage- five toddler (age 12 to 18 months) who experiments without anticipating the results.

deferred imitation A sequence in which an infant first perceives something that someone else does and then performs the same action a few hours or even days later.

Stages Five and Six: Tertiary Circular Reactions In their second year, infants start experimenting in deed and in thought, typically acting first and thinking later. Tertiary circular reactions begin when 1-year- olds take their first independent and varied actions to discover the properties of other people, animals, and things. Infants no longer simply respond to their own bodies (primary reactions) or to other people or objects (secondary reactions); they also begin new sequences, in a pattern more like a spiral than a closed circle.

The first stage of tertiary circular reactions, Piaget’s stage five (age 12 to 18 months), is called new means through active experimentation. This builds on the accomplishments of stage four, but goal-directed and purposeful activities become more expansive and creative. Toddlerhood is a time of active exploration, when babies delight in squeezing all the toothpaste out of the tube, taking apart the iPod, uncovering the anthill.

Piaget referred to the stage-five toddler as a “little scientist” who “experi- ments in order to see.” Their scientific method is trial and error. Their devotion to discovery is familiar to every adult scientist—and to every parent.

Finally, in the sixth stage (age 18 to 24 months), toddlers begin to anticipate and solve simple problems by using mental combinations, an intellectual experi- mentation that supersedes the active experimentation of stage five. The child is able to put two ideas together, such as that a doll is not a real baby but a doll can be belted into a stroller and taken for a walk. Because they combine ideas, stage- six toddlers think about consequences, hesitating a moment before yanking the cat’s tail or dropping a raw egg on the floor. Their strong impulse to discover sometimes overwhelms reflection; they do not always choose wisely. But at least thought precedes action.

Being able to use mental combinations makes it possible for the child to pre- tend. A toddler might sing to a doll before tucking it into bed. This is in marked contrast to the younger infant, who treats a doll like any other toy, throwing or bit- ing it, or to the stage-five toddler, who tries to pull off the head, arms, and legs to see what is inside.

Piaget describes another stage-six intellectual accomplishment, involving both thought and memory. Deferred imitation occurs when infants copy behavior they noticed hours or even days earlier (Piaget, 1962). A classic example is Piaget’s daughter, Jacqueline, who observed another child

who got into a terrible temper. He screamed as he tried to get out of a playpen and pushed it backward, stamping his feet. Jacqueline stood watching him in amazement, never having witnessed such a scene before. The next day, she herself screamed in her playpen and tried to move it, stamping her foot lightly several times in succession.

[Piaget, 1962, p. 63]

Sensorimotor Intelligence 159

then vanished, became two objects, or moved in an unexpected way. This reaction suggests object permanence, in that the in- fants seemed to think the object still existed behind the screen (Baillargeon, 1994).

Further exploration of infant cognition came from a series of experiments in which 2-, 4-, and 6-month-olds watched balls moving behind a screen, sometimes disappearing, sometimes reemerging in a smooth path, sometimes reemerging in the wrong place (Johnson et al., 2003). The 2-month-olds showed no awareness of anything odd, no matter what the balls did; the 4-month-olds showed signs that they knew something was

amiss; the 6-month-olds demonstrated (with attentive stares) that they expected the balls to move in the usual way and were surprised when they didn’t.

These researchers do not believe that the concept of object permanence (or, at least, perception regarding object trajectories) is inborn. It is the result of maturation and experience, as Piaget thought. The difference between this research and Piaget’s is the age at which infants demonstrate the concept. With clever experiments (i.e., relying on visual tracking rather than on the motor skills involved in reaching), researchers have shown that object permanence begins to emerge at 41⁄2 months.

Bib and Bath Learning to use eating utensils is a cognitively stimulating experience that is largely a matter of trial and—often messy— error.

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Especially for Parents One parent wants to put all the breakable or dangerous objects away because a toddler is now able to move around independently. The other parent says that the baby should learn not to touch certain things. Who is right?

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Piaget and Research Methods Infants reach the various stages of sensorimotor intelligence earlier than Piaget predicted. Not only do 41⁄2-month-olds comprehend object permanence, but many researchers have found that babies pretend and defer imitation as early as 9 months (Bauer, 2006; Meltzoff & Moore, 1999).

One reason Piaget underestimated the speed of infant cognition is that he based his conclusions on what he could see his own three infants do. Direct ob- servation of only three children is a start, but no contemporary researcher would stop there. There are problems with “fidelity and credibility” (Bornstein et al., 2005, p. 287) in collecting data on infants; modern researchers have statistics, design, sample size, and new strategies to overcome these problems (Hartmann & Pelzel, 2005). For example, habituation (from the word habit) refers to getting used to an experience after repeated exposure to it. Habituation occurs when the school cafeteria serves macaroni day after day or when an infant repeatedly hears the same sound, sees the same picture, plays with the same toy. Evidence of habit- uation is loss of interest (or, for macaroni, loss of appetite).

Using habituation as a research strategy involves repeating one stimulus until babies lose interest and then presenting another, slightly different stimulus (a new sound, sight, or other sensation). Babies can indicate in many ways—a longer or more focused gaze; a faster or slower heart rate; more or less muscle tension around the lips; a change in the rate, rhythm, or pressure of suction on a nipple— that they detect a difference between the two stimuli. These often subtle indica- tors are recorded by technology that was unavailable to Piaget.

By inducing habituation and then presenting a new stimulus, scientists have learned that even 1-month-olds can detect the difference between a pah sound and a bah sound, between a circle with two dots inside it and a circle without any dots, and much more. Babies younger than 6 months perceive far more than Piaget imagined.

More recent techniques involve measurement of brain activity (see Table 6.2) (Johnson, 2005). In functional magnetic resonance imaging, or fMRI, a burst of electrical activity within the brain is recorded, indicating that neurons are firing, which leads researchers to conclude that a particular stimulus has been noticed

fMRI Functional magnetic resonance imaging, a measuring technique in which the brain’s electrical excitement indicates activation any- where in the brain; fMRI helps researchers locate neurological responses to stimuli.

habituation The process of getting used to an object or event through repeated expo- sure to it.

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I’m Listening This 14-month-old is a master at deferred imitation. He knows how to hold a cell phone and what gestures to use as the “conversation” goes on.

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TABLE 6.2

Some Techniques Used by Neuroscientists to Understand Brain Function

Technique Use Limitations EEG (electroencephalogram)

ERP (event-related potential)

fMRI (functional magnetic resonance imaging)

PET (positron emission tomography)

Especially in infancy, much brain activity of interest occurs below the cortex.

Reaction within the cortex signifies perception, but interpretation of the amplitude and timing of brain waves is not straightforward.

Signifies brain activity, but infants are notoriously active, which can make fMRIs useless.

Many parents and researchers hesitate to inject radioactive dye into an infant’s brain unless a serious abnormality is suspected.

Measures electrical activity in the top layers of the brain, where the cortex is.

Notes the amplitude and frequency of electrical activity (as shown by brain waves) in specific parts of the cortex in reaction to various stimuli.

Measures changes in blood flow anywhere in the brain (not just the outer layers).

Also (like fMRI) reveals activity in various parts of the brain. Locations can be pinpointed with precision, but PET requires injection of radioactive dye to light up the active parts of the brain.

For both practical and ethical reasons, these techniques have not been used with large, representative samples of normal infants. One of the challenges of neuroscience is to develop methods that are harmless, easy to use, and comprehensive for the study of normal children.

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and processed. Using such advanced methods, scientists have been convinced that infants have memories, goals, and even mental combinations in advance of Piaget’s stages.

As explained in Chapter 5, many measurements of neurons show that early brain development is wide-ranging: Dendrites proliferate, and pruning is extensive. The first years of life are filled with mental activity and may be prime time for cognitive development (Johnson, 2005). In fact, discoveries have given develop- mentalists a new worry: People might think that these years are the only ones for brain growth. Not so. As 20 leading developmentalists explain, the

focus on “zero to three” as a critical or particularly sensitive period is highly problematic, not because this isn’t an important period for the developing brain, but . . . attention to the period from birth to 3 years begins too late and ends too soon.

[National Research Council and Institute of Medicine, 2000, p. 7]

SUMMING UP

Piaget discovered, described, and then celebrated active infant learning, which he de- scribed in six stages of sensorimotor intelligence. Babies use their senses and motor skills to gain an understanding of their world, first with reflexes and then by adapting through assimilation and accommodation. Object permanence, pursuit of goals, and deferred imitation all develop earlier in infancy than Piaget realized. The infant is a little scientist, not only at age 1, as Piaget described so well, but even in the first months of life. Thinking develops before motor skills can execute thoughts.

■

Information Processing Piaget was a “grand” theorist of cognition; he had an appreciation of shifts in the nature of cognition that occur at about ages 2, 6, and 12 years. His sweeping over- view, with its notion of distinct stages, contrasts with information-processing theory, a perspective modeled on computer functioning, including input, mem- ory, programs, calculation, and output.

Information-processing theorists believe that a step-by-step description of the mechanisms of thought add insight to our understanding of cognition at every age. Human information processing begins with input picked up by the five senses; proceeds to brain reactions, connections, and stored memories; and concludes with some action, such as a word or gesture. For infants, the output might be moving a hand to uncover a toy (object permanence), saying a word (e.g., mama) to signify recognition, or simply staring at a new photo (habituation). For example, instead of crying reflexively at the pain of hunger, an infant might focus on a bottle, remember that it can relieve hunger, reach for it, and then suck on it. Each step of this process requires information processing except the reflexive sucking, and even with that, the older infant is much more effective than the newborn because of better information processing.

With the aid of the sensitive technology just described, information-processing research has found some impressive intellectual capacities in the infant. For ex- ample, concepts and categories seem to develop in the infant brain by about 6 months (Mandler, 2004; Quinn, 2004). This perspective helps tie together various aspects of infant cognition. We review two of these now: affordances and memory. Affordances concern perception or, by analogy, input. Memory concerns brain organization and output—that is, information storage and retrieval.

information-processing theory A perspective that compares human thinking processes, by analogy, to computer analysis of data, including sensory input, connections, stored memories, and output.

Information Processing 161

➤Response for Parents (from page 159): It is easier and safer to babyproof the house, because toddlers, being “little scientists,” want to explore. However, it is important for both parents to encourage and guide the baby, so it is preferable to leave out a few untouchable items if that will help prevent a major conflict between husband and wife.

Especially for Computer Experts In what way is the human mind not like a computer?

➤Response for Parents (from page 157): Both decisions should be made within the first month, during the stage of reflexes. If parents wait until the infant is 4 months or older, they may discover that they are too late. It is difficult to introduce a bottle to a 4- month-old who has been exclusively breast- fed or a pacifier to a baby who has already adapted the sucking reflex to a thumb.

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Affordances Perception, remember, is the mental processing of information that arrives at the brain from the sensory organs. It is the first step of information processing the input to the brain. One of the puzzles of development is that two people can have discrepant perceptions of the same situation, not only interpreting it differently but actually observing it differently.

Decades of thought and research led Eleanor and James Gibson to conclude that perception is far from automatic (E. Gibson, 1969; J. Gibson, 1979). Percep- tion—for infants, as for the rest of us—is a cognitive accomplishment that re- quires selectivity: “Perceiving is active, a process of obtaining information about the world. . . . We don’t simply see, we look” (E. Gibson, 1988, p. 5).

The Gibsons contend that the environment (people, places, and objects) affords, or offers, many opportunities for perception and for interaction with what is per- ceived (E. Gibson, 1997). Each of these opportunities is called an affordance. Which particular affordance is perceived and acted on depends on four factors: sen- sory awareness, immediate motivation, current development, and past experience.

As a simple example, a lemon may be perceived as something that affords smelling, tasting, touching, viewing, throwing, squeezing, and biting (among other things). Each of these affordances is further perceived as offering pleasure, pain, or some other emotion. Which of the many affordances a particular person per- ceives and acts on depends on the four factors just mentioned: sensations, mo- tives, age, and experience. Consequently, a lemon might elicit quite different perceptions from an artist about to paint a still life, a thirsty adult in need of a re- freshing drink, and a teething baby wanting something to gnaw on.

Clearly, infants and adults perceive quite different affordances. A toddler’s idea of what affords running might be any unobstructed surface—a meadow, a long hallway in an apartment building, or a road. To an adult eye, the degree to which these places afford running may be restricted by such factors as a bull grazing in the meadow, neighbors in the hallway, or traffic on the road. Moreover, young chil- dren love to run, so they notice affordances for running; some adults prefer to stay put—so they do not perceive whether running is afforded or not.

affordance An opportunity for perception and interaction that is offered by a person, place, or object in the environment.

162 CHAPTER 6 ■ The First Two Years: Cognitive Development

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Look at Me These 1-year-olds are just learning about the affordances of objects. Thus, a rattle may be pushed against a friend’s face to gain the friend’s attention. This “little scientist” has not yet discovered that doing so may not be a good idea.

Observation Quiz (see answer, page 164): Are these two toddlers boys or girls?

Baby in Charge As this mother no doubt re- alizes, for her toddler, playing with blocks af- fords touching, stacking, and tossing them, not trying to identify the letters and numbers on them.

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➤Response for Computer Experts (from page 161): In dozens of ways, including speed of calculation, ability to network across the world, and vulnerability to viruses. In one crucial way the human mind is better: Computers crash within a few years, while human minds keep working until death.

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visual cliff An experimental apparatus that gives an illusion of a sudden drop between one horizontal surface and another.

Research on Early Affordances As information processing improves over the first year, infants become quicker to recognize affordances. A detailed study traced the responses of infants to eight dif- ferent displays on a TV screen (Courage et al., 2006; see Research Design). This research measured, among other things, how many times the infants glanced away from the displays, how long their most extensive look lasted, and whether their heart rate slowed down. The older infants were quicker to process the display and decide if it was interesting, a sign of better information processing. For example, the 14-week-olds looked at static dots for 10 seconds at a time, the 20-week-olds for 6 seconds, and babies from 26 to 52 weeks for only 5 seconds.

Developmental trends were apparent, especially for the most interesting dis- play, which was a video from Sesame Street. Babies stared at this video for an aver- age of 18 seconds at 14 weeks (usually one long look), 10 seconds at 26 months, and then back up to 15 seconds at 52 months. According to the researchers, input became quicker with age (hence shorter looks for less interesting things), but cog- nitive processing advanced (hence more intense looks at Sesame Street) (Courage et al., 2006).

Affordances are sought by infants of every age. For instance, one study found that when 9- to 12-month-olds were presented with unknown objects that rattled, rang, squeaked, or were silent, they decided what noise the object afforded on the basis of whether the object’s shape was similar to that of another noise-making object. By 12 months, they also used vocabulary: They predicted the noise that an object would make according to whether the object’s name was like the name of another object that, they knew, rattled, rang, or squeaked (Graham et al., 2004).

In another experiment, 12- to 24-month-olds watched adults look at or bend a laminated photograph and then followed the example, either looking at or bending it themselves. They did not yet know that photos are primarily for viewing, so they used whichever affordance they had been shown (Callaghan et al., 2004).

Sudden Drops The fact that experience affects which affordances are perceived is quite apparent in studies of depth perception. This research began with an apparatus called the visual cliff, designed to provide the illusion of a sudden dropoff between one horizontal surface and another. Mothers were able to urge their 6-month-olds to wiggle toward them over the supposed edge of the cliff, but even with mothers urging, 10-month-olds fearfully refused to budge (E. Gibson & Walk, 1960).

Researchers once thought that inade- quate depth perception kept young ba- bies from seeing the drop and that, as the visual cortex became more mature, 8-month-olds could see it. Later research (using advanced technology) found that that interpretation was wrong. Even 3- month-olds notice a drop: Their heart rate slows and their eyes open wide when they are placed over the cliff. But until

Information Processing 163

Research Design Scientists: Mary L. Courage, Greg D. Reynolds, and John E. Richards.

Publication: Child Development (2006).

Participants: One hundred infants aged 14, 20, 26, 39, and 52 weeks (20 at each age). None had birth complications or known disabilities. Each was tested sit- ting in the mother’s lap.

Design: Babies saw eight displays on a TV monitor, four of them motionless (a face, dots, triangles and lines, a Sesame Street scene) and the other four show- ing the same objects in motion. Dura- tion of looking was measured in seconds by researchers who did not know what the babies saw, and heart rate was measured via an electrocardio- gram (EEG).

Major conclusions: Look time and heart rate varied by age and display. Moving displays captured attention more than static ones; human forms were more at- tractive than geometric designs.The youngest babies often just stared blankly (and showed almost no slowing of heart rate), while the older babies glanced, glanced away, and then looked more closely. Age differences suggested advances in processing; the oldest ba- bies were most “stimulus dependent”— that is, most influenced by the specifics of what they saw.

Comment:This study provides rich data on age and information processing, in- cluding one table with 360 data points—72 at each age.This richness complicates analysis, but because the study compares heart rate, look time, age, and display, its conclusions are more reliable.

Depth Perception This toddler in a labora- tory in Berkeley, California, is crawling on the experimental apparatus called a visual cliff. She stops at the edge of what she perceives as a dropoff.MA

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they can crawl, they do not realize that crawling over an edge affords falling, per- haps with a frightening and painful result. This depends, of course, on each infant’s particular history. The difference is in processing, not input; in affordance, not mere perception. The same process happens with walking: Novice walkers are fear- less and reckless; experienced walkers are more cautious and deliberate (Adolph & Berger, 2005).

Movement and People Despite all the variations from one infant to another in the particular affordances they perceive, two general principles of perception are shared by all infants: dynamic perception and people preference. Both of these principles were demon- strated by the study of the 8 displays mentioned above (Courage et al., 2006).

Dynamic perception is primed to focus on movement and change. Infants love motion. As soon as they can, they move their own bodies—grabbing, scooting, crawling, walking. To their delight, these movements change what the world af- fords them; as a result, perception and body motion advance as quickly as possible (Adolph & Berger, 2005).

Other creatures that move, especially their own caregivers, are among the first and best sources of pleasure, again because of dynamic perception. That is one reason it’s almost impossible to teach a baby not to chase and grab a moving dog, a cat, or even a cockroach.

The other universal principle of infant perception is people preference. This characteristic may have evolved over the centuries because humans of all ages sur- vived by learning to attend to, and rely on, one another. As you remember from Chapter 5, all human senses are primed to respond to social stimuli (Bornstein et al., 2005).

Very young babies are interested in the emotional affordances of their care- givers (whether a person is likely to elicit laughter or fear), using their limited per- ceptual abilities to respond to smiles, shouts, and so on. Infants connect facial expressions with tone of voice long before they understand language. This ability has led to an interesting hypothesis:

Given that infants are frequently exposed to their caregivers’ emotional displays and further presented with opportunities to view the affordances (Gibson, 1959, 1979) of those emotional expressions, we propose that the expressions of famil- iar persons are meaningful to infants very early in life.

[Kahana-Kalman & Walker-Andrews, 2001, p. 366]

Building on earlier research by other scientists on infant perception, these re- searchers presented infants with two moving images on a video screen. Both im- ages were of a woman, either their mother or a stranger. In one, the woman visibly expresses joy; in the other, sorrow. Each image is accompanied by an audiotape

of that woman’s happy or sad talk. By 7 months, but not before, babies show that they can match emotional words with facial expressions by looking longer at the face expressing the same emotion as in the tone of voice.

Some infants in this experiment were only 31⁄2 months old. When they did not know the woman, they failed to match the ver- bal emotion with the facial expression. In other words, when the face was that of a stranger, these 31⁄2-month-olds did not tend to look more at the happy face when they heard the happy talk or to match sad voice and sad face.

However, when the 31⁄2-month-olds saw their own mother on the video (two images, happy and sad) and heard her happy or her

dynamic perception Perception that is primed to focus on movement and change.

people preference A universal principle of infant perception, consisting of an innate attraction to other humans, which is evi- dent in visual, auditory, tactile, and other preferences.

164 CHAPTER 6 ■ The First Two Years: Cognitive Development

One Constant, Multisensual Perception From the angle of her arm and the bend of her hand, it appears that this infant recognizes the constancy of the furry mass, perceiving it as a single entity whether it is standing still, rolling in the sand, or walking along the beach.

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Especially for Parents of Infants When should you be particularly worried that your baby will fall off the bed or down the stairs?

➤Answer to Observation Quiz (from page 162): Surprise! Both babies are girls, named Anne and Sarah. Illustrating the power of stereotyping, many observers would have guessed that they are boys because their blue garments afford masculinity.

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sad voice, they correctly matched visual and vocal emotions. They looked longest at their happy mothers talking in a happy way, but they also looked at their sad mothers when they heard their mother’s sad voice—an amazing display of con- necting speech tone with facial expressions.

The researchers noticed something else. When infants saw and heard their happy mothers, as opposed to the happy strangers, they smiled twice as quickly, seven times as long, and much more brightly (with cheeks raised as well as lips up- turned) (Kahana-Kalman & Walker-Andrews, 2001). Obviously, experience had taught these babies that a smiling mother affords joy. The affordances of a smiling stranger are difficult to judge.

Memory A certain amount of experience and brain maturation are required in order to process and remember experiences. Infants have great difficulty storing new memories in their first year, and older children are often un- able to describe events that occurred when they were younger. But on the basis of a series of experiments, developmentalists now agree that very young infants can remember under the following circumstances:

■ Experimental conditions are similar to real life. ■ Motivation is high. ■ Special measures are taken to aid memory retrieval.

The most dramatic evidence for infant memory comes from a series of innovative experiments in which 3-month-olds were taught to make a mobile move by kicking their legs (Rovee-Collier, 1987, 1990). The in- fants lay on their backs, in their own cribs, connected to a mobile by means of a ribbon tied to one foot (see photograph).

Virtually all the infants began making some occasional kicks (as well as random arm movements and noises) and realized, after a while, that kick- ing made the mobile move. They then kicked more vigorously and fre- quently, sometimes laughing at their accomplishment. So far, this is no surprise—self-activated movement is highly reinforcing to infants, part of dynamic perception.

When some infants had the mobile-and-ribbon apparatus reinstalled in their cribs one week later, most started to kick immediately; this reaction indicated that they remembered their previous experience. But when other infants were retested two weeks later, they began with only random kicks. Apparently they had forgotten what they had learned—evidence that memory is fragile early in life.

Reminders and Repetition The lead researcher, Carolyn Rovee-Collier, developed another experiment that demonstrated that 3-month-old infants could remember after two weeks if they had a brief reminder session before being retested (Rovee-Collier & Hayne, 1987). A reminder session is any perceptual experience that is intended to help a person recollect an idea, a thing, or an experience.

In this particular reminder session, two weeks after the initial training, the in- fants watched the mobile move but were not tied to it and were positioned so that they could not kick. The next day, when they were again connected to the mobile and positioned so that they could move their legs, they kicked as they had learned to do two weeks earlier.

Watching the mobile move on the previous day revived their faded memory. The information about how to make the mobile move was stored in their brains;

Especially for Parents This research on early affordances suggests a crucial lesson about how many babysitters an infant should have. What is it?

reminder session A perceptual experience that is intended to help a person recollect an idea, a thing, or an experience, without testing whether the person remembers it at the moment.

Information Processing 165

He Remembers! In this demonstration of Rovee-Collier’s experiment, a young infant immediately remembers how to make the fa- miliar mobile move. (Unfamiliar mobiles do not provoke the same reaction.) He kicks his right leg and flails both arms, just as he learned to do several weeks ago.

Observation Quiz (see answer, page 167): How and why is this mobile unlike those usually sold for babies?

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they needed some processing time to retrieve it. The reminder session provided that time. Overall, some early memories can be “highly enduring, and become even more so after repeated encounters with reminders” (Rovee-Collier & Ger- hardstein, 1997).

A Little Older, a Little More Memory After about 6 months, infants can retain information for longer periods of time than younger babies can, with less training or reminding. Toward the end of the first year, many kinds of memory, including that involved in deferred imitation, are apparent (Meltzoff & Moore, 1999). For example, suppose a 9-month-old watches someone playing with a toy he or she has never seen before. The next day, if given the toy, the 9-month-old is likely to play with it in the same way as he or she had observed. (Younger infants do not.)

By the middle of the second year, toddlers can remember and reenact more complex sequences. In one study, 16- and 20-month-olds watched an experi- menter perform various activities, such as putting a doll to bed, making a party hat, and cleaning a table (Bauer & Dow, 1994). For each activity, the experimenter used props and gave a brief “instruction” for performing each step. For instance, to clean the table, the experimenter wet it with water from a white spray bottle, say- ing, “Put on the water”; wiped it with a paper towel, saying, “Wipe it”; and placed the towel in a wooden trash basket, saying, “Toss it.”

A week later, most toddlers remembered how to carry out the sequence when they heard “Put on the water. Wipe it. Toss it.” They followed what they had seen, not only with the same props but also with different props (for instance, a clear spray bottle, a sponge, and a plastic garbage can). This shows that infants are de- veloping concepts, not imitating behavior (Mandler, 2004). Many other experi- ments also show that toddlers are thinking conceptually, not just repeating what they have experienced.

Aspects of Memory Memory is not one thing, “not a unitary or monolithic entity” (Schacter & Badgaiyan, 2001, p.1). People are inaccurate when they make general statements about their “memory,” as in “I have a good memory” or “My memory is failing.” Brain-imaging techniques (such as fMRI) reveal many distinct brain regions de- voted to particular aspects of memory. There is probably a memory for faces, for sounds, for events, for sights, for phrases, and much more.

One distinction is between implicit memory, which is memory for routines and memories that remain hidden until a particular stimulus brings them to mind (like the mobile), and explicit memory, which is memory that can be recalled on de- mand. As you can see in Table 6.3, explicit memory is probably impossible in the first months of life. Some aspects of it are evident after age 1 (see Chapter 9); at about age 5 or 6, when children begin school, explicit memory improves dramati- cally as those parts of the brain mature (Nelson et al., 2006).

Because there are so many types of memory, it is not surprising that infants re- member some things better than others: That’s the way human brains are con- structed. Thus, early memories may be either fragile or enduring, depending on which type of memory is involved (Nelson & Webb, 2003).

Infants probably store within their brains many emotions and sensations that they cannot readily retrieve, whereas memories of motion (dynamic perception) are remembered once that particular action is cued by the context (as when the infants remembered how to kick to make the mobile move). Once they under- stand words, a verbal reminder aids retrieval, even after a delay (Bauer, 2006).

166 CHAPTER 6 ■ The First Two Years: Cognitive Development

Memory Aid Personal motivation and action are crucial to early memory, and that is why Noel has no trouble remembering which shape covers the photograph of herself as a baby.

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➤Response for Parents of Infants (from page 164): Constant vigilance is necessary for the first few years of a child’s life, but the most dangerous age is from about 4 to 8 months, when infants can move but do not yet have a fear of falling over an edge.

➤Response for Parents (from page 165): It is important that infants have time for repeated exposure to each caregiver, because infants adjust their behavior to maximize whatever each particular caregiver affords in the way of play, emotions, and vocalization. Parents should find one steady babysitter rather than several.

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SUMMING UP

Infant cognition can be studied using the information-processing perspective, which analyzes each component of how thoughts begin and are organized, remembered, and expressed. Infant perception is powerfully influenced by particular experiences and motivation, so the affordances perceived by one infant differ from those perceived by another. Memory depends on both brain maturation and experience. That is why mem- ory is fragile in the first year (being increased by dynamic perception and reminders) and becomes more evident (although many types of memory remain quite fragile) in the second year.

■

Language: What Develops in the First Two Years? The acquisition of language, with its thousands of words, idiomatic phrases, gram- mar rules, and exceptions, is the most impressive intellectual achievement of the young child. In fact, language is the most impressive human accomplishment: It differentiates Homo sapiens from all other species, and it may be the reason human brains are more complex than those of other animals (Leonard, 2003).

For instance, humans and gorillas are close relatives, with about 99 percent of their genes in common. Gorillas are bigger than people, but an adult gorilla’s brain is only one-third as big as a human’s and has far fewer dendrites, synapses, and other components. This means that a 2-year-old human has twice as much brain- power as a full-grown gorilla. Many animals communicate, but no species has any- thing approaching the neurons and networks that support the 6,000 human languages.

Language: What Develops in the First Two Years? 167

TABLE 6.3

The Major Memory Systems and Developmental Tasks

Brain Systems General System Subsystems Tasks Related to Tasks Infancy Example Implicit memory (nondeclarative memory)

Explicit memory

Rare before age 1

Procedural learning

Conditioning

Perceptual representation system

Pre-explicit memory

Semantic memory (generic knowledge)

Episodic memory (autobiographical)

Serial reaction time (SRT) task

Visual expectation paradigm (VExP)

Conditioning

Perceptual priming paradigms

Novelty detection in habituation and paired comparison tasks

Semantic retrieval, word priming, and associative priming

Episodic encoding

Recall and recognition

Striatum, supplementary motor association, motor cortex, frontal cortex

Frontal cortex, motor areas

Cerebellum, basal ganglia

Modality dependent; parietal cortex, occipital cortex, inferior temporal cortex, auditory cortex

Hippocampus

Left prefrontal cortex, anterior cingulate cortex, hippocampal cortex

Left prefrontal cortex, left orbitoprefrontal cortex

Right prefrontal cortex, anterior cingulate cortex, parietal cortex, cerebellum, hippocampal cortex

Kick to make mobile move

Laugh when tickled

Recognize mother’s voice

Hear difference between sounds

First spoken words

Remember usual routines of dinner

Remember when and how a painful event occurred

Source: Adapted from Nelson & Webb, 2003, p. 103.

➤Answer to Observation Quiz (from page 165): It is black and white, with larger objects—designed to be particularly attractive to infants, not to adult shoppers.

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The Universal Sequence The timing of language acquisition varies; the most advanced 10 percent of 2-year-olds speak more than 550 words, and the least advanced 10 percent speak fewer than 100 words—a fivefold difference (Merri- man, 1999). (Some explanations are discussed at the end of this chapter.) But children around the world follow the same sequence of early language devel- opment (see Table 6.4).

Listening and Responding Infants begin learning language before birth, via brain organization and auditory experiences during the final prenatal months. Newborns prefer to hear speech over other sounds; they prefer to listen to high- pitched, simplified, and repetitive adult speech. This

form of speech is quite distinct from normal speech. It is sometimes called baby talk, since it is talk directed to babies, and sometimes called motherese, since mothers all over the world speak it. Both these terms may have misleading impli- cations, so scientists prefer the more formal term child-directed speech.

Newborns respond to adult noises and expressions (as well as to their own in- ternal pleasures and pain) in many ways, crying, cooing, and making a variety of other sounds even in the first days of life. Their responses gradually become more varied. By 4 months, most babies squeal, growl, gurgle, grunt, croon, and yell, as well as make speechlike sounds (Hsu et al., 2000).

child-directed speech The high-pitched, simplified, and repetitive way adults speak to infants. (Also called baby talk or motherese.)

168 CHAPTER 6 ■ The First Two Years: Cognitive Development

TABLE 6.4

AT ABOUT THIS TIME: The Development of Spoken Language in the First Two Years

Age* Means of Communication Newborn

2 months

3–6 months

6–10 months

10–12 months

12 months

13–18 months

18 months

21 months

24 months

Reflexive communication—cries, movements, facial expressions

A range of meaningful noises—cooing, fussing, crying, laughing

New sounds, including squeals, growls, croons, trills, vowel sounds

Babbling, including both consonant and vowel sounds repeated in syllables

Comprehension of simple words; speechlike intonations; specific vocalizations that have meaning to those who know the infant well. Deaf babies express their first signs; hearing babies also use specific gestures (e.g., pointing) to communicate.

First spoken words that are recognizably part of the native language

Slow growth of vocabulary, up to about 50 words

Vocabulary spurt—three or more words learned per day. Much variation: Some toddlers do not yet speak.

First two-word sentence

Multiword sentences. Half the toddler’s utterances are two or more words long.

*The ages of accomplishment in this table reflect norms. Many healthy children with normal intelligence attain these steps in language development earlier or later than indicated here. Source: Bloom, 1993, 1998; Fenson et al., 2000; Lenneberg, 1967.

Too Young for Language? No. The early stages of language are communication through noises, gestures, and facial expres- sions, very evident here between this !Kung grandmother and granddaughter.

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Babbling Between 6 and 9 months, babies begin to repeat certain syllables (ma-ma-ma, da-da-da, ba-ba-ba), a phenomenon referred to as babbling because of the way it sounds. Babbling is experience-expectant; all babies do it, even deaf ones. Responses encourage babbling; deaf babies stop (because they cannot hear re- sponses) and hearing babies continue. All babies make rhythmic gestures, waving their arms as they babble, again in response to the actions of others (Iverson & Fagan, 2004). Toward the end of the first year, babbling begins to sound like the native language; infants imitate what they hear.

Videotapes of deaf children whose parents sign to them show that 10-month- old deaf infants use about a dozen distinct hand gestures—which resemble the signs their parents use—in a repetitive manner similar to babbling. Parents of hearing babies should also use gestures; children understand and express con- cepts with gestures sooner than with speech (Goldin-Meadow, 2006).

Pointing is an advanced gesture that requires understanding another person’s perspective. Most animals cannot interpret pointing; most humans can do so at 10 months. This is one of the intriguing aspects of human development, since point- ing indicates a strong preference for social interaction.

First Words Finally, at about 1 year of age, the average baby speaks (or signs) a few words. Usually, caregivers understand the first word before strangers do, which makes it hard for researchers to pinpoint exactly what a 12-month-old can say. For example, at 13 months, Kyle knew standard words such as mama, but he also knew da, ba, tam, opma, and daes, which his parents knew to be, respectively, “downstairs,” “bottle,” “tummy,” “oatmeal,” and “starfish” (yes, that’s what daes meant) (Lewis et al., 1999).

In the first months of the second year, spoken vocabulary increases very gradu- ally (perhaps one new word a week). However, 6- to 15-month-olds learn mean- ings rapidly, and they comprehend about 10 times as many words as they speak (Schafer, 2005; Snow, 2006).

The Naming Explosion Once vocabulary reaches about 50 expressed words (understood words are more extensive), it builds rapidly, at a rate of 50 to 100 words per month, with 21- month-olds saying twice as many words as 18-month-olds (Adamson & Bakeman, 2006). This language spurt is called the naming explosion because many of the early words are nouns, or naming words (Gentner & Boroditsky, 2001).

In almost every language, each significant caregiver (often dada, mama, nana, papa, baba, tata), sibling, and sometimes pet is named between 12 and 18 months (Bloom, 1998). (See Appendix A, p. A-4.) Other frequently uttered words refer to the child’s favorite foods and to elimination (pee-pee, wee-wee, poo-poo, ka-ka, doo-doo).

No doubt you have noticed that all these words have a similar structure: two identical syllables, each a consonant followed by a vowel sound. Many more words follow that pattern—not just baba but also bobo, bebe, bubu, bibi. Others are slightly more complicated—not just mama but also ma-me, ama, and so on.

Cultural Differences Although all new talkers say names, using similar sounds, and say more nouns than any other part of speech, the ratio of nouns to verbs and adjectives shows cultural

naming explosion A sudden increase in an infant’s vocabulary, especially in the num- ber of nouns, that begins at about 18 months of age.

Language: What Develops in the First Two Years? 169

babbling The extended repetition of certain syllables, such as ba-ba-ba, that begins between 6 and 9 months of age.

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Lip-Reading Communication begins in early infancy. Infants closely watch speakers’ mouth movements and facial expressions. By this baby’s age, 5 months, bilingual infants can tell by looking who is speaking French and who is speaking English.

Especially for Caregivers A toddler calls two people “Mama.” Is this a sign of confusion?

Especially for Nurses and Pediatricians The parents of a 10-month-old have just been told that their child is deaf. They don’t believe it, because, as they tell you, the baby doesn’t always respond to noises, but he babbles as much as their other children did. What do you tell them?

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influences (Bornstein et al., 2004). For example, by 18 months, English-speaking infants use relatively more nouns but fewer verbs than Chinese or Korean infants do. Why?

One explanation goes back to the language itself. Chinese and Korean are “verb-friendly,” in that verbs are placed at the beginning or end of sentences, which makes them easier to learn. In English, verbs occur in various positions within sentences, and their forms change in illogical ways (think of go, gone, will go, went). This irregularity makes English verbs harder than nouns for novice learners (Gentner & Boroditsky, 2001).

An alternative explanation considers the entire social context: Playing with a variety of toys and learning about dozens of objects are crucial in North American culture, whereas East Asian cultures emphasize human interactions—specifically, how one person responds to another. Accordingly, North American infants are ex- pected to name many objects, whereas Asian infants are expected to encode social interactions into language.

Every language has some concepts encoded in adult speech that are easy and some that are hard for infants. English-speaking infants confuse before and after; Dutch-speaking infants misuse out when it refers to taking off clothes; Korean infants need to learn two meanings of in (Mandler, 2004).

Learning adjectives is easier in Italian and Spanish than in English or French because of patterns in those languages (Waxman & Lidz, 2006). Specifically, adjectives can stand by themselves without the nouns. If I want a blue cup from a group of multicolored cups, I would ask for “a blue cup” or “a blue one” in English but simply “uno azul” (a blue) in Spanish. Despite such variations, in every language, infants demonstrate impressive speed and efficiency in acquiring both vocabulary and grammar (Bornstein et al., 2004).

Sentences The first words soon take on nuances of tone, loudness, and cadence that are precursors of the first grammar, because a single word can convey many messages by the way it is spoken. Imagine meaningful sentences encapsulated in “Dada!” “Dada?” and “Dada.” Each is a holophrase, a single word spoken in such a way that it expresses an entire thought (Tomasello, 2006).

holophrase A single word that is used to express a complete, meaningful thought.

170 CHAPTER 6 ■ The First Two Years: Cognitive Development

Where in the World? Different cultures influ- ence children’s language learning in different ways. Children who spend a lot of time with adults receive abundant exposure to the unique speech patterns of their culture.

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➤Response for Caregivers (from page 169): Not at all. Toddlers hear several people called “Mama” (their own mother, their grandmothers, their cousins’ and friends’ mothers) and experience mothering from several people, so it is not surprising if they use “Mama” too broadly. They will eventually narrow the label down to the one correct person.

➤Response for Nurses and Pediatricians (from page 169): Urge the parents to accept the diagnosis and take action. They should begin learning sign language immediately and investigate the possibility of cochlear implants. Babbling has a biological basis and begins at a specified time, in deaf as well as hearing babies. However, deaf babies eventually begin to use gestures more and to vocalize less than hearing babies.

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Intonation (variations of tone and pitch) is extensive in babbling and again in holophrases at about 18 months, with a dip in between (at about 12 months). At that one-year point, infants seem to reorganize their vocalization from universal to language-specific (Snow, 2006). They are no longer just singing and talking to themselves (babbling) but communicating with others (uttering holophrases).

Grammar includes all the methods that languages use to communicate meaning. Word order, prefixes, suffixes, intonation, verb forms, pronouns and negations, prepositions and articles—all of these are aspects of grammar. Gram- mar is obvious when two-word combinations begin, at about 21 months. These sentences follow the word order “Baby cry” or “More juice,” rather than the reverse. Soon the child is combining three words, usually in subject–verb–object order in English (for example, “Mommy read book”), rather than any of the five other possible sequences of those words.

A child’s grammar correlates with the size of his or her vocabulary (Snow, 2006). The child who says “Baby is crying” is advanced in language development compared with the child who says “Baby crying” or simply the holophrase “Baby” (Dionne et al., 2003). Comprehension advances as well. Their expanding knowl- edge of both vocabulary and grammar helps toddlers understand what others are saying (Kedar et al., 2006).

If the child’s family is bilingual, the acquisition of language is not slowed down, but “development in each language proceeds separately and in a language-specific manner” (Conboy & Thal, 2006, p. 727). Thus an English–French bilingual child who understands the word on does not yet necessarily understand sur.

Theories of Language Learning Worldwide, people who are not yet 2 years old already use language well. Bilingual children keep two languages separate, and speak whatever language a given lis- tener understands. Some teenagers compose lyrics or deliver orations that move thousands of their co-linguists. Some adults are fluent in two, three, or even more languages. For many older adults, cognitive abilities decline, but language contin- ues to advance. How do these amazing examples of language learning happen?

Answers come from three schools of thought, each of which is connected to a theory (behaviorism, epigenetic theory, and sociocultural theory, respectively). The first says that infants are directly taught, the second that infants naturally under- stand language, and the third that social impulses propel infants to communicate.

Each theory of language acquisition has implications for parents and educators, all of whom want children to speak fluently, but none of whom want to teach something that infants cannot learn or that they will learn without instruction. Which theory should guide them?

Theory One: Infants Need to Be Taught The seeds of the first perspective were planted more than 50 years ago, when the dominant theory in North American psychology was behaviorism, or learning theory. The essential idea was that all learn- ing is acquired, step by step, through association and reinforcement. Just as Pavlov’s dogs learned to associate the sound of a bell with the presentation of food (see Chapter 2), behaviorists believe that infants associate objects with words they have heard often, especially if rein- forcement occurs.

B. F. Skinner (1957) noticed that spontaneous babbling is usually reinforced. Typically, every time the baby says “ma-ma-ma-ma,” a grin- ning mother appears, repeating the sound as well as showering the

grammar All the methods—word order, verb forms, and so on—that languages use to communicate meaning, apart from the words themselves.

Language: What Develops in the First Two Years? 171

Cultural Values If his infancy is like that of most babies raised in the relatively taciturn Ottavado culture of Ecuador, this 2-month-old will hear significantly less conversation than infants from most other regions. According to many learning theorists, a lack of reinforce- ment will result in a child who is insufficiently verbal. In most Western cultures, that might be called maltreatment. However, each cul- ture tends to encourage the qualities it most needs and values, and verbal fluency is not a priority in this community. In fact, people who talk too much are ostracized and those who keep secrets are valued, so encourage- ment of language may be maltreatment here.

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baby with attention, praise, and perhaps food. These affordances of mothers are ex- actly what the infant wants, and the baby will make those sounds again to get them.

Most parents are excellent instructors. For instance, parents who talk to their young infants typically name each object—“Here is your bottle,” “There is your foot,” “You want your juice?” and so on—often touching and moving the named object at the same time as they speak the target word loudly, clearly, and slowly (Gogate et al., 2000). They also use child-directed speech, capturing the baby’s interest with high pitch, short sentences, stressed nouns, and simple grammar— exactly the kind of teaching techniques that behaviorists would recommend.

The core ideas of this theory are the following:

■ Parents are expert teachers, although other caregivers help. ■ Frequent repetition is instructive, especially when linked to daily life. ■ Well-taught infants become well-spoken children.

Behaviorists note that some 3-year-olds converse in elaborate sentences; others just barely put one simple word with another. Such variations correlate with the amount of language teaching the child receives. Parents of the most verbal chil- dren teach language throughout infancy—singing, explaining, listening, respond- ing, and reading. For instance, parents of the most verbal children typically read to them every day, even at age 1 (Raikes et al., 2006; see Research Design).

Providing another example, researchers analyzed the language that mothers (all middle-class) used with their preverbal infants, aged 9 to 17 months (Tamis- LeMonda et al., 2001). One mother never imitated her infant’s babbling; another mother imitated 21 times in 10 minutes, babbling back as if in conversation. Over- all, mothers were most likely to describe things or actions (e.g., “That is a spoon you are holding—spoon”). The range was vast: In 10 minutes, one mother described things only 4 times, while another provided her baby with 33 descriptions.

The frequency of maternal responsiveness at 9 months predicted language ac- quisition many months later (see Figure 6.1). It was not that noisy infants, whose genes would soon make them start talking, elicited more talk from their mothers. Some quiet infants had noisy mothers, who suggested play activities, described things, and asked questions. Quiet infants with talkative mothers usually became talkative later on.

This research is in keeping with the behaviorist theory that adults teach lan- guage and then infants learn it. If adults want language-proficient children who speak, understand, and (later) read well, they must talk to their babies.

Especially for Nurses and Pediatricians Bob and Joan have been reading about language development in children. They are convinced that language is “hardwired,” so they need not talk to their 6-month-old son. How do you respond?

172 CHAPTER 6 ■ The First Two Years: Cognitive Development

100

80

60

40

20

0 13.0 15.0 17.0

Age in months

19.0 21.0

Percent of infants knowing at least 50 words

Infants of highly responsive mothers

Infants of less responsive (bottom 10 percent) mothers

Source: Adapted from Tamis-LeMonda et al., 2001, p. 761.

FIGURE 6.1

Maternal Responsiveness and Infants’ Language Acquisition Learning the first 50 words is a milestone in early language acqui- sition, as it predicts the arrival of the naming explosion and the multiword sentence a few weeks later. Researchers found that half the infants of highly responsive mothers (top 10 percent) reached this milestone as early as 15 months of age and the other half reached it by 17 months. The infants of nonresponsive mothers (bottom 10 percent) lagged signifi- cantly behind.

Research Design Scientists: Helen Raikes, Barbara Alexandra Pan, Gayle Luze, Catherine S. Tamis-LeMonda, Jeanne Brooks-Gunn, Jill Constantine, et al.

Publication: Child Development (2006).

Participants: From 17 Early Head Start programs, 2,581 mother–infant pairs were interviewed. All were low income; 26 percent were married; 53 percent were high school graduates. About a third each were Americans of European, African, and Hispanic heritage.

Design:When the infants were 14, 24, and 36 months old, their language abil- ity was measured and the mothers were asked how often they read to them and how many books the babies had.The children’s language abilities were compared to 15 variables.

Major conclusions: Being read to corre- lated with language, but early reading (at 14 months) was not as strong a pre- dictor of future language scores as were two other factors, maternal warmth and education. By 36 months, children whose mothers read to them often were quite verbal.

Comment:The size and diversity of this sample add to confidence in the conclu- sions. Being read to as a baby is one of many factors that foster language. Some of the details of this study could be used to confirm all three theories of language learning discussed here.

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Theory Two: Infants Teach Themselves A contrary theory holds that language learning is innate; adults need not teach it. The seeds of this perspective were planted soon after Skinner proposed his theory of verbal learning. Noam Chomsky (1968, 1980) and his followers felt that lan- guage is too complex to be mastered merely through step-by-step conditioning. Although behaviorists focus on variations among children in vocabulary size, Chomsky focused on similarities in language acquisition.

Noting that all young children master basic grammar at about the same age, Chomsky cited this universal grammar as evidence that humans are born with a mental structure that prepares them to seek some elements of human language— for example, the use of a raised tone at the end of an utterance to indicate a question. Chomsky labeled this hypothesized mental structure the language acquisition device, or LAD. The LAD enables children to derive the rules of grammar quickly and effectively from the speech they hear every day, regardless of whether their native language is English, Thai, or Urdu.

Other scholars agree with Chomsky that infants are innately ready to use their minds to understand and speak whatever language is offered (Gopnik, 2001). The various languages of the world, as different as they are from one another, are all logical, coherent, and systematic. Infants, who are also logical, are primed to grasp the particular language they are exposed to, making caregiver speech “not a ‘trigger’ but a ‘nutrient’” (Slobin, 2001, p. 438). There is no need for a language trigger, according to theory two, because words are “expected” by the developing brain, which quickly and efficiently connects neurons in the first year to support whichever particular language the infant hears.

Research supports this perspective as well. As you remember, all infants babble ma-ma and da-da sounds (not yet referring to mother or father) (Goldman, 2001). No reinforcement or teaching is needed; all infants need is for dendrites to grow, mouth muscles to strengthen, neurons to connect, and speech to be heard. Then, in the second year, infants shape their noisemaking quickly to whatever language they hear. Toddlers are naturally endowed to learn vocabulary simply by overhear- ing it, as many parents discover—occasionally to their dismay (Akhtar et al., 2001).

Theory Three: Social Impulses Foster Infant Language The third theory is called social-pragmatic because it perceives the crucial starting point to be neither vocabulary reinforcement (behaviorism) nor the innate con- nection (epigenetic), but rather the social reason for language: communication.

Language: What Develops in the First Two Years? 173

language acquisition device (LAD) Chomsky’s term for a hypothesized mental structure that enables humans to learn language, including the basic aspects of grammar, vocabulary, and intonation.

Show Me Where Pointing is one of the earli- est forms of communication, emerging at about 10 months. As Carlos demonstrates, accurate pointing requires a basic under- standing of social interaction, because the pointer needs to take the observer’s angle of vision into account.MI

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➤Answer to Observation Quiz (from page 170): At least four elements are unusual in today’s Western families: large size (four children), a child held in the mother’s lap to eat (i.e., no high chair for the baby), the father pouring for everyone, and the fact that the whole family, including teenagers, is eating together. This family lives in Mozambique, in southeastern Africa.

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According to this perspective, infants communicate in every way they can because humans are social be- ings, dependent on one another for survival and joy.

Newborns look searchingly at human faces and listen intently to human voices because they seek to respond to emotions, not because they want to know content. Before age 1, infants vocalize, babble, ges- ture, listen, and point—with an outstretched little index finger that is soon accompanied by a very so- phisticated glance to see if the other person is look- ing at the right spot. These and many other examples show that communication is the servant of social in- teraction (Bloom, 1998).

Here is an experiment. Suppose an 18-month-old is playing with an unnamed toy and an adult utters a word. Does the child connect that word to the toy? A

behaviorist, learning-by-association prediction would be yes, but the answer is no. When toddlers played with a fascinating toy and adults said a word, the toddlers looked up, figured out what the adult was looking at, and assigned the new word to that, not to the fascinating toy (Baldwin, 1993). This supports theory three: The toddlers were socially focused.

According to theory three, then, social impulses, not explicit teaching or brain maturation (as in the first two perspectives), lead infants to learn language, “as part of the package of being a human social animal” (Hollich et al., 2000). They seek to understand what others want and intend, and therefore “children acquire linguistic symbols as a kind of by-product of social action with adults” (Tomasello, 2001).

A Hybrid Theory Which of these three perspectives is correct? As you can see, each position has been supported by research. Scholars have attempted to integrate all three per- spectives, notably in a monograph based on 12 experiments designed by eight researchers (Hollich et al., 2000). The authors developed a hybrid (which literally means “a new creature, formed by combining other living things”) of previous the- ories. They called their model an emergentist coalition because it combines valid aspects of several theories about the emergence of language during infancy.

These researchers point out that children learn language to do numerous things—indicate intention, call objects by name, put words together, talk to family members, sing to themselves, express their wishes, remember the past, and much more. Therefore, the scientists hypothesize that some aspects of language are best learned in one way at one age, others in another way at another age.

For example, the name of the family dog may be learned by association and rep- etition, with family members and eventually the dog itself reinforcing the name, a behaviorist process. However, the distinction between cat and dog may reflect a neurological predilection (epigenetic), which means that the human brain may be genetically wired to differentiate those species.

Which theory do you think explains the fact that the 6-month-old’s ability to hear a difference in sounds predicts that child’s ability to talk at 13 months, 18 months, and 24 months? This could be the result of listening to many words (behaviorist), of inborn potential (Chomsky), or of social impulses (sociocultural). After intensive study, the scientists who reported that hearing differences lead to spoken proficiency endorsed a hybrid theory, concluding that “multiple atten-

Especially for Babysitters Should you do anything for your clients’ infants besides keeping them safe and clean?

174 CHAPTER 6 ■ The First Two Years: Cognitive Development BR

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Not Talking? No words yet, but this infant communicates well with Dad, using eyes, mouth, and hands. What are they telling each other?

➤Response for Nurses and Pediatricians (from page 172): While much of language development is indeed hardwired, many experts assert that exposure to language is required. You don’t need to convince Bob and Joan of this point, though—just convince them that their baby will be happier if they talk to him.

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tional, social and linguistic cues” contribute to early language (Tsao et al., 2004, p. 1081).

Another study supporting the hybrid theory began, as did a study previously mentioned (Baldwin, 1993), with infants looking at objects that they had never seen and never heard named. One of each pair was fascinating to babies and the other was boring, specifically “a blue sparkle wand . . . [paired with] a white cabi- net latch . . . a red, green, and pink party clacker . . . [paired with] a beige bottle opener” (Pruden et al., 2006, p. 267).

The experimenter said a made-up name (not an actual word), and then the in- fants were tested to see if they assigned the word to the object that had the exper- imenter’s attention (the dull one) or the one that was interesting to the child. These were 10-month-old infants, not 18-month-old toddlers as in the earlier ex- periment, and they seemed to assign the word to the fascinating object, not the dull one. This response is what behaviorists, not social-pragmatists, would predict, because the more rewarding object was named.

These researchers interpret their experiment as supporting the emergentist- coalition model, which holds that how language is learned depends on the par- ticular circumstances. Behaviorism works for young children, social learning for slightly older ones: “The perceptually driven 10-month-old becomes the socially aware 19-month-old” (Pruden et al., 2006, p. 278).

It makes logical and practical sense for nature to provide several paths toward language learning. Each path may be preferred or more efficient in some stages, cultures, and families, but every child learns to communicate and uses a variety of ways to do so. This hybrid perspective returns the child to center stage: Infants are active learners not only of the concepts described in the first half of this chapter but also of language, and they use many ways to master knowledge. As one expert concludes:

Word learning theories will have to come to terms with the fact that children . . . are more than perceivers, receivers, or possessors of external supports. Instead, the word learning child is a child with feelings and thoughts about other persons, a child engaged in dynamic real-life events, a child learning to think about a world of changing physical and psychological relationships—in short, a child poised to act, to influence, to gain control . . . to embrace the learning of language for the power of expression it provides.

[Bloom, 2000, p. 13]

SUMMING UP

From the first days of life, babies attend to words and expressions, responding as well as their limited abilities allow—crying, cooing, and soon babbling. Before age 1, they un- derstand simple words and communicate with gestures. At 1 year, most infants speak. Vocabulary accumulates slowly at first, but then more rapidly with the naming explosion and with the emergence of the holophrase and the two-word sentence.

The impressive language learning of the first two years can be explained in many ways. One theory contends that caregivers must teach language, reinforcing the infant’s vocal expressions. Another theory relies on the idea of an inborn language acquisition device, a mental structure that facilitates the acquisition of language as soon as matura- tion makes that possible. A third theory stresses social interaction, implying that infants learn language because they are social beings. A hybrid model combines all three of these theories. Because infants vary in culture, learning style, and social context, the hybrid theory acknowledges that each of the other theories may have some validity at different points in the acquisition of language.

■

Language: What Develops in the First Two Years? 175

Especially for Educators An infant day- care center has a new child whose parents speak a language other than the one the teachers speak. Should the teachers learn basic words in the new language, or should they expect the baby to learn the majority language?

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176 CHAPTER 6 ■ The First Two Years: Cognitive Development

Sensorimotor Intelligence 1. Piaget realized that very young infants are active learners, seeking to understand their complex observations and experiences. Adaptation in infancy is characterized by sensorimotor intelli- gence, the first of Piaget’s four stages of cognitive development. At every time of their lives, people adapt their thoughts to the experiences they have.

2. Sensorimotor intelligence develops in six stages—three pairs of two stages each—beginning with reflexes and ending with the toddler’s active exploration and use of mental combinations. In each pair of stages, development occurs in one of three types of circular reactions, or feedback loops, in which the infant takes in experiences and tries to make sense of them.

3. Reflexes provide the foundation for intelligence. The continual process of assimilation and accommodation is evident in the first acquired adaptations, from about 1 to 4 months. The sucking re- flex accommodates the particular nipples and other objects that the baby learns to suck. As time goes on, infants become more goal-oriented, creative, and experimental as “little scientists.”

4. Infants gradually develop an understanding of objects over the first two years of life. As shown in Piaget’s classic experiment, in- fants understand object permanence and begin to search for hid- den objects at about 8 months. Other research finds that Piaget underestimated the cognition of young infants.

Information Processing 5. Another approach to understanding infant cognition is infor- mation-processing theory, which looks at each step of the think- ing process, from input to output. The perceptions of a young infant are attuned to the particular affordances, or opportunities for action, that are present in the infant’s world.

6. Objects that move are particularly interesting to infants, as are other humans. Objects as well as people afford many possibilities for interaction and perception, and therefore these affordances enhance early cognition.

7. Infant memory is fragile but not completely absent. Reminder sessions help trigger memories, and young brains learn motor sequences long before they can remember verbally. Memory is multifaceted; explicit memories are rare in infancy.

Language:What Develops in the First Two Years? 8. Eager attempts to communicate are apparent in the first year. Infants babble at about 6 to 9 months, understand words and ges- tures by 10 months, and speak their first words at about 1 year.

9. Vocabulary begins to build very slowly until the infant knows approximately 50 words. Then a naming explosion begins. Toward the end of the second year, toddlers begin putting two words to- gether, showing by their word order that they understand the rudiments of grammar.

10. Various theories attempt to explain how infants learn lan- guage as quickly as they do. The three main theories emphasize different aspects of early language learning: that infants must be taught, that their brains are genetically attuned to language, and that their social impulses foster language learning.

11. Each of these theories seems partly true. The challenge for developmental scientists has been to formulate a hybrid theory that uses all the insights and research on early language learning. The challenge for caregivers is to respond appropriately to the in- fant’s early attempts to communicate.

sensorimotor intelligence (p. 155)

primary circular reactions (p. 156)

secondary circular reactions (p. 157)

object permanence (p. 158)

tertiary circular reactions (p. 159)

“little scientist” (p. 159) deferred imitation (p. 159) habituation (p. 160) fMRI (p. 160) information-processing theory

(p. 161)

affordance (p. 162) visual cliff (p. 163) dynamic perception (p. 164) people preference (p. 164) reminder session (p. 165) child-directed speech (p. 168) babbling (p. 169)

naming explosion (p. 169) holophrase (p. 170) grammar (p. 171) language acquisition device

(LAD) (p. 173)

SUMMARY

KEY TERMS

4. Why are some researchers concerned about too much empha- sis being placed on early brain development?

5. How do researchers figure out whether an infant has a con- cept of something even if the infant cannot talk about it yet?

6. What does research on affordances suggest about cognitive differences between one infant and another?

1. Why is Piaget’s first period of cognitive development called sensorimotor intelligence? Give examples.

2. Give examples of some things adults learn via sensorimotor intelligence.

3. What does the active experimentation of the stage-five toddler suggest for parents?

KEY QUESTIONS

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Summary 177

10. How would a caregiver who subscribes to the behaviorist the- ory of language learning respond when an infant babbles?

11. According to the sociocultural theory of language learning, what might explain why an 18-month-old is not yet talking?

12. What does the research on language learning suggest to care- givers?

7. Why would a child remember very little about experiences in infancy?

8. What indicates that toddlers use some grammar?

9. How do deaf and hearing babies compare in early language learning?

3. Many educators recommend that parents read to babies even before the babies begin talking. What theory of language develop- ment does this reflect?

4. Test an infant’s ability to search for a hidden object. Ideally, the infant should be about 7 or 8 months old, and you should retest over a period of weeks. If the infant can immediately find the object, make the task harder by pausing between the hiding and searching or by secretly moving the object from one hiding place to another.

1. Elicit vocalizations from an infant—babbling if the baby is under age 1, words if older. Write down all the baby says for 10 minutes. Then ask the primary caregiver to elicit vocalizations for 10 minutes, and write these down. What differences are apparent between the baby’s two attempts at communication? Compare your findings with the norms described in the chapter.

2. Piaget’s definition of intelligence is adaptation. Others con- sider a good memory or an extensive vocabulary to be a sign of in- telligence. How would you define intelligence? Give examples.

APPLICATIONS

➤Response for Educators (from page 175): Probably both. Infants love to communicate, and they seek every possible way to do so. Therefore, the teachers should try to understand the baby, and the baby’s parents, but should also start teaching the baby the majority language of the school.

➤Response for Babysitters (from page 174): Yes. Babies need to hear language, so you can assist in their language development by talking and singing to them.

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The First Two Years: Psychosocial Development

The dynamic interaction of infants’ emotions and their social con-texts is the substance of this chapter. You have witnessed thisinterplay whenever you have seen a tiny baby smile at an engagingface or a toddler flop to the floor, kicking and screaming, after being told “no.” I continue to be surprised by mothers and babies.

As I sat on a crowded subway train, a young woman boarded with an infant in one arm and a heavy shopping bag on the other. She tried to steady herself as the train started to move. I asked, “Can I help you?” Wordlessly she handed me . . . the baby. I began softly singing a children’s song. The baby was very quiet, keeping her eyes on her mother. That was a psycho- social moment for all three of us.

This chapter opens with a much longer psychosocial episode, the early development of a boy named Jacob. Then we trace infant emotions over the first two years. This discussion is followed by a review of the five theories first described in Chapter 2, with an overview of what each has to say about psychosocial development in infancy. This leads us into an exploration of research on caregiver–infant interaction, particularly synchrony, attachment, and social referencing—all pivotal to psychosocial development. We then consider the pros and cons of infant day care. The chapter ends with practi- cal suggestions regarding Jacob, whose story appears below.

7

179

CHAPTER OUTLINE

A CASE TO STUDY: Parents on Autopilot

� Emotional Development Specific Emotions Self-Awareness

� Theories About Infant Psychosocial Development

Psychoanalytic Theory Behaviorism Cognitive Theory Epigenetic Theory Sociocultural Theory A CASE TO STUDY: “Let’s Go to Grandma’s”

� The Development of Social Bonds Synchrony THINKING LIKE A SCIENTIST:

The Still-Face Technique Attachment Social Referencing Infant Day Care

� Conclusions in Theory and Practice

a case to study Parents on Autopilot

A father writes about his third child, Jacob:

[My wife, Rebecca, and I] were convinced that we were set. We had surpassed our quota of 2.6 children and were ready to engage parental autopilot. I had just begun a prestigious job and was working 10–11 hours a day. The children would be fine. We hired a nanny to watch Jacob during the day. As each of Jacob’s early milestones passed, we felt that we had taken another step toward our goal of having three normal children. We were on our way to the perfect American family. Yet, somewhere back in our minds

we had some doubts. Jacob seemed different than the girls. He had some unusual attributes. There were times when we would be holding him and he would arch his back and scream so loud that it was painful for us.

[Jacob’s father, 1997, p. 59]

As an infant, Jacob did not relate to his parents (or to anyone else). His parents paid little heed to his psychosocial difficul- ties, focusing instead on physical development. They noted that Jacob sat up and walked on schedule, and when they “had some doubts,” they found excuses, telling themselves that “boys are

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Emotional Development Within the first two years, infants progress from reactive pain and pleasure to complex patterns of social aware- ness (see Table 7.1). This is the period of life with “high emotional responsiveness” (Izard et al., 2002, p. 767), marked by speedy, uncensored reactions—crying, star- tling, laughing, raging—and, by toddlerhood, complex responses, from self-satisfied grins to mournful pouts.

Specific Emotions At first there is pleasure and pain. Newborns look happy and relaxed when fed and drifting off to sleep. They cry when they are hurt or hungry, are tired or

frightened (as by a loud noise or a sudden loss of support), or have colic, the recur- rent bouts of uncontrollable crying and irritability that afflict about a third of all infants in the early months.

Soon, additional emotions become recognizable (Lavelli & Fogel, 2005). Curi- osity is increasingly evident as infants distinguish the unusual from the familiar (Kagan, 2002). Happiness is expressed by the social smile in response to a human face at about 6 weeks and by laughter at about 3 or 4 months. Parents elicit laugh- ter, and so do adept strangers. Among the Navajo, whoever brings forth that first laugh gives a feast to celebrate that the baby is becoming a person (Rogoff, 2003). Laughter builds as curiosity does, so that a typical 6-month-old not only discovers new things but also laughs loudly, with evident joy.

Anger is evident at 6 months, usually triggered by frustration. It is most appar- ent when infants are prevented from reaching a graspable object or moving as they wish (Plutchik, 2003). One-year-olds hate to be strapped in, caged in, closed in, or just held tight on someone’s lap when they want to explore. Anger in infancy is a healthy response to frustration, unlike sadness, which also appears in the first months. Sadness indicates withdrawal and is accompanied by an increase in the level of cortisol, a stress hormone (M. Lewis & D. Ramsay, 2005). Reliable hormone assays are more difficult with infants than with older people, so not all the hor- monal changes that accompany infant emotions are known. However, the fact that sadness brings stress suggests that sorrow is not a superficial emotion for infants.

social smile A smile evoked by a human face, normally evident in infants about 6 weeks after birth.

180 CHAPTER 7 ■ The First Two Years: Psychosocial Development

different” or that Jacob’s language delays stemmed from the fact that his nanny spoke little English. As time went on, however, their excuses fell short. His father continues:

Jacob had become increasingly isolated [by age 2]. I’m not a psy- chologist, but I believe that he just stopped trying. It was too hard, perhaps too scary. He couldn’t figure out what was ex- pected of him. The world had become too confusing, and so he withdrew from it. He would seek out the comfort of quiet, dark places and sit by himself. He would lose himself in the bright, colorful images of cartoons and animated movies.

[Jacob’s father, 1997, p. 62]

Jacob was finally diagnosed at age 3 with “pervasive develop- mental disorder.” This is a catchall diagnosis that can include

autism (discussed in Chapter 11). At the moment, you need to know only that Jacob’s psychosocial potential was unappreciated. His despairing parents were advised to consider residential placement because Jacob would always need special care and, with Jacob living elsewhere, they would not be constantly re- minded of their “failure.” This recommendation did not take into account the commitment that Jacob’s parents, like most parents, felt toward their child.

Yet, despite their commitment, they had ignored signs of trou- ble, overlooking their son’s sometimes violent reaction to being held and his failure to talk. The absence of smiling, of social play, and of imitation should have raised an alarm. The father’s use of the word autopilot shows that he realized this in hindsight. Later in this chapter, you will learn the outcome.

TABLE 7.1

AT ABOUT THIS TIME: Ages When Emotions Emerge

Age Emotional Expression Birth Crying; contentment

6 weeks Social smile

3 months Laughter; curiosity

4 months Full, responsive smiles

4–8 months Anger

9–14 months Fear of social events (strangers, separation from caregiver)

12 months Fear of unexpected sights and sounds

18 months Self-awareness; pride; shame; embarrassment

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Fully formed fear in response to some person, thing, or situation (not just dis- tress at a surprise) emerges at about 9 months and then rapidly becomes more fre- quent as well as more apparent (Kagan, 1998). Two fears are obvious:

■ Stranger wariness, when an infant no longer smiles at any friendly face, and cries if an unfamiliar person moves too close, too quickly

■ Separation anxiety, expressed in tears, dismay, or anger when a familiar caregiver leaves

Separation anxiety is normal at age 1, intensifies by age 2, and usually subsides after that. If it remains strong after age 3, it is considered an emotional disorder (Silverman & Dick-Niederhauser, 2004).

Many 1-year-olds fear not just strangers but also anything unexpected, from the flush of a toilet to the pop of a jack-in-the-box, from the sudden closing of elevator doors to the friendly approach of a dog. With repeated expe- riences and caregiver protection, older infants might themselves enjoy flushing the toilet (again and again) or calling the dog (crying if the dog does not come).

Many emotions that emerge in the first months of life take on new strength at about age 1 (Kagan, 2002). Throughout the second year and beyond, anger and fear typically become less frequent but more focused, targeted toward infuriating or terrifying experiences. Similarly, laughing and crying become louder and more discriminating.

New emotions appear toward the end of the second year: pride, shame, embarrassment, and guilt. These emotions require an awareness of other people. They emerge from family interactions, influenced by the culture (Eid & Diener, 2001). For example, pride is encouraged in North American toddlers (“You did it all by yourself”—even when that is

stranger wariness An infant’s expression of concern—a quiet stare, clinging to a famil- iar person, or sadness—when a stranger appears.

separation anxiety An infant’s distress when a familiar caregiver leaves; most obvious between 9 and 14 months.

Emotional Development 181

Friendship Begins Emotions connect friends to each other—these two 1-year-olds as well as friends of any age. The shared smiles indicate a strong social connection. What will they do next?GE

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untrue), but Asian families discourage pride and cultivate modesty and shame (Rogoff, 2003).

Two-year-olds have many emotional reactions. They are taught which expres- sions of emotion are acceptable and which are not (Saarni et al., 2006). For exam- ple, if a toddler holds on tightly to his mother’s skirt and hides his face when a friendly but strange dog approaches, the mother could pick the child up or bend down to pet the dog. The mother’s response encourages fear or happiness when a dog next appears.

Self-Awareness In addition to social interactions, another foundation for emotional growth is self- awareness, the infant’s realization that his or her body, mind, and actions are separate from those of other people (R. A. Thompson, 2006). At about age 1, an emerging sense of “me” and “mine” leads to a new consciousness of others. As one developmentalist explains:

With the emergence of consciousness in the second year of life, we see vast changes in both children’s emotional life and the nature of their social relation- ships. . . . The child can feel . . . self-conscious emotions, like pride at a job well done or shame over a failure.

[M. Lewis, 1997, p. 132]

Very young infants have no sense of self—at least, of self as some people define it. In fact, a prominent psychoanalyst, Margaret Mahler, theorized that for the first 4 months of life infants see themselves as part of their mothers. They “hatch” at about 5 months and spend the next several months developing a sense of them- selves as separate from their mothers (Mahler et al., 1975). The period from 15 to 18 months “is noteworthy for the emergence of the Me-self, the sense of self as the object of one’s knowledge” (Harter, 1998, p. 562).

In a classic experiment (M. Lewis & J. Brooks, 1978), babies aged 9–24 months looked into a mirror after a dot of rouge had been surreptitiously put on their noses. If the babies reacted by touching their noses, that meant they knew the mirror showed their own faces. None of the babies less than 12 months old re- acted as if they knew the mark was on them (they sometimes smiled and touched the dot on the “other” baby in the mirror). However, those between 15 and 24 months usually showed self-awareness, touching their own noses with curiosity and puzzlement.

Self-recognition usually emerges at about 18 months, at the same time as two other advances: pretending and using first-person pronouns (I, me, mine, myself, my). Some developmentalists connect self-recognition with self-understanding (e.g., Gallup et al., 2002), although “the interpretation of this seemingly simple task is plagued by controversy” (Nielsen et al., 2006, p. 166).

Pride and shame seem to be, at this phase, linked to the maturing self-concept, not necessarily to other people’s opinions. If someone tells a toddler, “You’re very smart,” the child may smile but usually already feels smart—and thus is already pleased and proud. Telling toddlers that they are smart, strong, or beautiful may even be unhelpful.

One longitudinal study found that positive comments from mothers to 2-year- olds did not lead to more pride or less shame by age 3 (Kelley et al., 2000). How- ever, certain negative comments (such as “You’re doing it all wrong”) diminished effort and increased shame. Neutral suggestions fostered a willingness to try new challenges. Toddlers’ self-esteem seems to result more from accomplishments than from praise.

self-awareness A person’s realization that he or she is a distinct individual, with body, mind, and actions that are separate from those of other people.

182 CHAPTER 7 ■ The First Two Years: Psychosocial Development

She Knows Herself This 18-month-old is happy to see herself in her firefighter’s hel- met. She is adjusting the helmet with her hands on it, and that’s evidence that she un- derstands what a mirror is. Note, however, that she is not yet aware that a hat has a front and a back.

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Especially for Nurses and Pediatricians Parents come to you concerned that their 1- year-old hides her face and holds onto them tightly whenever a stranger appears. What do you tell them?

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SUMMING UP

Newborns seem to have only two simple emotions, distress and contentment, which are expressed by crying or looking happy. Very soon curiosity and obvious joy, with social smiles and laughter, appear. By the second half of the first year, anger and fear are increasingly evident, especially in reaction to social experiences, such as encountering a stranger. In the second year, as infants become self-aware, they express emotions connected to themselves, including pride, shame, and embarrassment, and emotions about other people. Universal maturation makes these emotions possible at around 18 months, but context and learning affect their timing, frequency, and intensity.

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Theories About Infant Psychosocial Development The five major theories described in Chapter 2 have somewhat different perspec- tives on the origin and significance of infants’ emotions.

Psychoanalytic Theory Psychoanalytic theory connects biosocial and psychosocial development, empha- sizing the need for responsive maternal care. Both major psychoanalytic theorists, Sigmund Freud and Erik Erikson, described two distinct early stages. Freud (1935, 1940/1964) wrote about the oral stage and the anal stage. Erikson (1963) called his first stages trust versus mistrust and autonomy versus shame and doubt.

Freud: Oral and Anal Stages According to Freud (1935), psychological development in the first year of life is in the oral stage, so named because the mouth is the young infant’s primary source of gratification. In the second year, with the anal stage, the infant’s main pleasure comes from the anus—particularly from the sensual pleasure of bowel movements and, eventually, the psychological pleasure of controlling them.

Freud believed that both the oral and anal stages are fraught with potential conflicts that have long-term consequences. If a mother frustrates her infant’s urge to suck—weaning the infant too early, for example, or preventing the child from sucking on fingers or toes—the child may become distressed and anxious, eventually becoming an adult with an oral fixation. Such a person is stuck (fixated) at the oral stage and therefore eats, drinks, chews, bites, or talks excessively, in quest of the mouth-related pleasure denied in infancy.

Similarly, if toilet training is overly strict or if it begins before the infant is mature enough, parent–infant interaction may become locked into a conflict over the toddler’s refusal, or inability, to comply. The child becomes fixated and develops an anal personality—as an adult, seeking self-control with an unusually strong need for regularity in all aspects of life.

Erikson: Trust and Autonomy According to Erikson, the first crisis of life is trust versus mistrust, when infants learn whether the world can be trusted to satisfy basic needs. Babies feel secure when food and comfort are provided with “consistency, continuity, and sameness of experience” (Erikson, 1963, p. 247). If social interaction inspires trust and se- curity, the child (and later the adult) will confidently explore the social world.

trust versus mistrust Erikson’s first psy- chosocial crisis. Infants learn basic trust if the world is a secure place where their basic needs (for food, comfort, attention, etc.) are met.

Theories About Infant Psychosocial Development 183

Especially for Nursing Mothers You have heard that if you wean your child too early, he or she will overeat or become an alcoholic. Is it true?

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The next crisis is called autonomy versus shame and doubt. Toddlers want autonomy (self-rule) over their own actions and bodies. If they fail to gain it, they feel ashamed of their actions and doubtful about their abilities.

Some cultures encourage independence and autonomy (as in the United States); in others (for example, China) “shame is a normative emotion that develops as parents use explicit shaming techniques” to encourage children’s loyalty and harmony within their families (Mascolo et al., 2003, p. 402). Westerners expect toddlers to go through the stubborn and defiant “terrible twos”; parents in many non- Western societies expect the opposite.

Like Freud, Erikson believed that problems arising in early infancy could last a lifetime, creating an adult who is suspicious and pessimistic (mistrusting) or who is easily shamed (insufficient autonomy). These traits could be destructive or not, depending on the norms and expecta- tions of the culture.

Behaviorism From the perspective of behaviorism, emotions and personality are molded as par- ents reinforce or punish the child’s spontaneous behaviors. For example, if parents smile and pick up their infant at every glimmer of a grin, he or she will become a child—and later an adult—with a sunny disposition. The opposite is also true. Early behaviorists, especially John Watson, expressed this idea in very strong terms:

Failure to bring up a happy child, a well-adjusted child—assuming bodily health —falls squarely upon the parents’ shoulders. [By the time the child is 3] parents have already determined . . . [whether the child] is to grow into a happy person, wholesome and good-natured, whether he is to be a whining, complaining neurotic, an anger-driven, vindictive, over-bearing slave driver, or one whose every move in life is definitely controlled by fear.

[Watson, 1928, pp. 7, 45]

Later behaviorists noted that infants also experience social learning, which is learning by observing others, as in Albert Bandura’s experiment in which young children who had seen an adult punching a rubber Bobo clown treated the doll the same way (Bandura, 1977). Social learning is apparent in many families, when toddlers express emotions—from giggling to cursing—in much the same way their parents or older siblings do. A boy might develop a hot temper, for instance, if his father’s outbursts seem to win respect from his mother.

Both psychoanalytic and behaviorist theories emphasize parents. Freud thought that the mother was the young child’s first and most enduring “love object,” and behaviorists stress the power of a mother over her children. In retrospect, this focus seems too narrow. The other three theories reflect more recent research and the changing historical context.

Cognitive Theory Cognitive theory holds that thoughts and values determine a person’s perspective. Early experiences are important because beliefs, perceptions, and memories make them so, not because they are buried in the unconscious (psychoanalytic theory) or burned into the brain’s patterns (behaviorism).

Infants use their early relationships to develop a working model, a set of as- sumptions that become a frame of reference that can be called on later in life (Bretherton & Munholland, 1999; R. A. Thompson & Raikes, 2003). It is called a

social learning Learning by observing others.

working model In cognitive theory, a set of assumptions that the individual uses to organize perceptions and experiences. For example, a person might assume that other people are trustworthy, and be surprised when this model of human behavior seems in error.

184 CHAPTER 7 ■ The First Two Years: Psychosocial Development

A Mother’s Dilemma Infants are wonder- fully curious, as this little boy demonstrates. Parents, however, must guide as well as en- courage the drive toward autonomy. Notice this mother’s expression as she makes sure her son does not crush or eat the flower.

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autonomy versus shame and doubt Erikson’s second crisis of psychosocial development. Toddlers either succeed or fail in gaining a sense of self-rule over their own actions and bodies.

➤Response for Nurses and Pediatricians (from page 182): Stranger wariness is normal up to about 14 months. This baby’s behavior actually sounds like secure attachment!

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“model” because these early relationships form a prototype, or blueprint, for later relationships; it is called “working” because, while usable, it is not necessarily fixed or final.

For example, a 1-year-old girl might develop a working model, based on her par- ents’ inconsistent responses to her, that people are unpredictable. All her life she will apply that model whenever she meets a new person. Her childhood relation- ships will be insecure, and in adulthood she might be on guard against further disappointment. To use Piaget’s terminology, she has developed a cognitive schema to organize her perceptions. According to cognitive theory, a child’s interpretation of early experiences is crucial, not necessarily the experiences themselves (Schaffer, 2000).

The hopeful message of cognitive theory is that people can rethink and reorgan- ize their thoughts, developing new working models that are more positive than their original ones. Our mistrustful girl can learn to trust if her later experiences— such as marriage to a faithful and loving husband—provide a new model.

Epigenetic Theory As you remember from Chapter 2, epigenetic theory holds that every human char- acteristic is strongly influenced by each person’s unique genotype. Thus, a child might be happy or anxious not because of early experiences (the three grand theo- ries) but because of inborn predispositions. DNA remains the same from concep- tion on, no matter how emotions are blocked (psychoanalytic theory), reinforced (behaviorism), or interpreted (cognitive theory).

Temperament Among each person’s genetic predispositions are the traits of temperament, defined as “constitutionally based individual differences” in emotions, activity, and self-regulation (Rothbart & Bates, 2006, p. 100). “Constitutionally based” means that these traits originate with nature (genes) more than nurture.

The concept of temperament is similar to that of personality. Some researchers believe that the line between temperament and personality is unclear (e.g., Caspi & Shiner, 2006). Generally, however, personality traits (e.g., honesty and humility) are considered to be primarily learned, whereas temperamental traits (e.g., shy- ness and aggression) are considered to be primarily genetic. Although tempera- mental traits originate with the genes, the way these traits are expressed can be modified by experiences.

temperament Inborn differences between one person and another in emotions, activ- ity, and self-control. Temperament is epigenetic, originating in genes but affected by child-rearing practices.

Theories About Infant Psychosocial Development 185

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Twins They were born on the same day and now are experiencing a wading pool for the first time.

Observation Quiz (see answer, page 186): Are these babies monozygotic or dizygotic twins?

➤Response for Nursing Mothers (from page 183): Freud thought so, but there is no experimental evidence that weaning, even when ill timed, has such dire long-term effects.

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In laboratory studies of temperament, some infants have experi- ences that might be frightening. Four-month-olds might see spinning mobiles or hear unusual sounds. Older babies might confront a noisy, moving robot or a clown who quickly moves close. At such experi- ences, some children laugh (and are classified as “easy”), some cry (“difficult”), and some are quiet (“slow to warm up”) (Fox et al., 2001; Kagan & Snidman, 2004).

The categories of “easy,” “difficult,” and “slow to warm up” come from a classic study called the New York Longitudinal Study (NYLS). Begun in the 1960s, the NYLS was the first among many studies to recognize that each newborn has distinct inborn traits. Although tem- perament begins in the brain, it is difficult to detect via brain scans, so most of the research uses parents’ reports and direct observation. In order to avoid merely reflecting the parents’ hopes and biases, researchers ask for specifics. As the NYLS researchers explain:

If a mother said that her child did not like his first solid food, we . . . were satisfied only when she gave a description such as “When I put the food into his mouth he cried loudly, twisted his head away, and let it drool out.”

[Chess et al., 1965, p. 26]

According to the NYLS, by 3 months, infants manifest nine temperamental traits that can be clustered into the three categories described above, with a fourth category of “hard to classify” infants:

■ Easy (40 percent) ■ Difficult (10 percent) ■ Slow to warm up (15 percent) ■ Hard to classify (35 percent)

Other researchers began by studying adult personality traits and came up with the “Big Five” (whose first letters form the easy-to-remember acronym OCEAN):

■ Openness: imaginative, curious, welcoming new experiences ■ Conscientiousness: organized, deliberate, conforming ■ Extroversion: outgoing, assertive, active ■ Agreeableness: kind, helpful, easygoing ■ Neuroticism: anxious, moody, self-critical

As is further explained in Chapter 22, the Big Five traits are found in many cultures, among people of all ages (McCrae & Costa, 2003). This universality adds to the evidence that some basic temperamental differences are innate, preceding child-rearing practices and cultural values (Rothbart et al., 2000). The Big Five are more complex than the easy/difficult/slow-to-warm-up classifications; but an infant high in agreeableness might be classified as easy, one high in neuroticism would be difficult, and one low in openness would be slow to warm up.

The Parents’ Role Studies of temperament find that the traits found in the NYLS or described by the Big Five correspond to clusters of behaviors that appear early in life. Easy babies are happy and outgoing most of the time, adjusting quickly to almost any change. Difficult babies are the opposite: irregular, intense, unhappy, disturbed by every noise, and hard to distract—quite a handful. Slow-to-warm-up babies take their time to adapt to new people and experiences.

186 CHAPTER 7 ■ The First Two Years: Psychosocial Development

Which Sister Has a Personality Problem? Culture always affects the expression of tem- perament. In Mongolia and many other Asian countries, females are expected to display shyness as a sign of respect to elders and strangers. Consequently, if the younger of these sisters is truly as shy as she seems, her parents are less likely to be distressed about her withdrawn behavior than the typical North American parent would be. Conversely, they may consider the relative boldness of her older sister to be a serious problem.

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➤Answer to Observation Quiz (from page 185): True tests of zygosity involve analysis of blood type, although physical appearance often provides some clues. Here such clues are minimal: We cannot see differences in sex, coloring, or hand formation—although the shapes of the skulls seem different. The best clue from this photo is personality. Confronting their first experience in a wading pool, these twins are showing such a differ- ence on the approach–withdrawal dimension of temperament that they are probably dizygotic.

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One longitudinal study (Fox et al., 2001) identified three distinct groups— positive (exuberant), negative, and inhibited (fearful)—at 4 months. (Many infants fit into none of these groups.) The researchers followed the children in each group, with laboratory measures, mothers’ reports, and brain scans at 9, 14, 24, and 48 months. Half were very stable in temperament, reacting the same way and having similar brain-wave patterns when confronted with frightening experiences all four times they were tested.

The other half changed their reaction to frightening experiences on at least one later assessment. Those who had been fearful at 4 months were most likely to change, and the exuberant infants were least likely to change (see Figure 7.1). That speaks to the influence of child rearing, since parents and other adults are likely to coax frightened children to be braver but usually encourage happy chil- dren to stay positive.

In response to such adult guidance, infant temperament often changes. In gen- eral, however, the interaction between cultural influences and inherited traits tends to shape behavior by early childhood (Rothbart & Bates, 2006). Traits that are present at age 3 often are still evident at age 26 (Caspi et al., 2003).

Whatever their child’s temperament, parents need to find a goodness of fit— that is, a temperamental adjustment that allows smooth infant–caregiver inter- action. With a good fit, parents of difficult children are able to build a close relationship; parents of exuberant, curious children learn to protect them from harm; parents of slow-to-warm-up children give them time to adjust.

In general, stubborn and anxious children (i.e., high in neuroticism) are more affected by their mother’s responsiveness than positive children are (Pauli-Pott et al., 2004). Ineffective or harsh parenting combined with a negative temperament creates antisocial, destructive children (Caspi et al., 2002). Some children natu- rally cope easily with life’s challenges, whereas “a shy child must control his or her fear and approach a stranger, and an impulsive child must constrain his or her de- sire and resist a temptation” (Derryberry et al., 2003, p. 1061).

The epigenetic perspective emphasizes that inherited differences in tempera- ment are affected by parental behavior (Kagan & Fox, 2006). Parents must first

goodness of fit A similarity of temperament and values that produces a smooth inter- action between an individual and his or her social context, including family, school, and community.

Theories About Infant Psychosocial Development 187

Fearful at 9, 14, 24, and 48 months

42% Positive

(every later time) 12%

Fearful (every later time)

Variable (sometimes positive, sometimes not)

Variable (sometimes fearful, sometimes not)

44%

Positive at 9, 14, 24, and 48 months

80%

Inhibited (fearful) at 4 months and . . . Positive (exuberant) at 4 months and . . .

Changes in Temperament Between Ages 4 Months and 4 Years

Source: Adapted from Fox et al., 2001.

15%

5%

FIGURE 7.1

Do Babies’ Temperaments Change? The data suggest that fearful babies are not nec- essarily fated to remain that way. Adults who are reassuring and do not act frightened them- selves can help children overcome an innate fearfulness. Some fearful children do not change, however, and it is not known whether that’s because their parents are not suffi- ciently reassuring (nurture) or because they are temperamentally more fearful (nature).

Observation Quiz (see answer, page 188): Out of 100 4-month-olds who react positively to noises and other experiences, how many are fearful at later times in early childhood?

Especially for Nurses and Pediatricians Parents come to you with their fussy 3- month-old. They say that they have read that temperament is “fixed” before birth, and they are worried that their child will always be difficult. What do you tell them?

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understand their child’s temperamental traits and then teach and guide the child so that those inborn traits are expressed constructively, not destructively.

Many developmentalists caution against too much emphasis on genes, espe- cially in infancy when observations of actual interactions suggest that the mother’s parenting style has more influence on the infant’s behavior than the infant’s temperament does (Roisman & Fraley, 2006). At the same time, it is important to remember that inborn temperament is evident in brain activity as well as in reactions from early infancy, and it influences behavior from childhood through old age (Kagan & Snidman, 2004). (Parenting styles and attitudes are discussed in Chapters 10 and 13.)

Sociocultural Theory No one doubts that “human development occurs in a cultural context” (Kagitcibasi, 2003, p. 166). The crucial question is how much influence culture has. Sociocul- tural theorists argue that the influence is substantial, that the entire social and cultural context has a major impact on infant–caregiver relationships and thus on infant development.

Ethnotheories An ethnotheory is a theory that is embedded in a particular culture or ethnic group (Dasen, 2003). Usually the group members are unaware that their theories underlie their customs. However, as you have already seen with breast-feeding and co-sleeping, many child-rearing practices are connected to ethnotheories (Greenfield et al., 2003).

This is true for emotional development as well. For example, if a culture’s ethno- theory includes the idea that ancestors are reincarnated in the younger generation, then “children are not expected to show respect for adults, but adults [are expected to show respect] for their reborn ancestors.” Such cultures favor indulgent child- rearing practices, with no harsh punishments. “Western people perceive [these cultures] as extremely lenient” (Dasen, 2003, pp. 149–150).

For example, we noted earlier that infants become angry when they are re- strained. Nonetheless, many European American parents force their protesting toddlers to sit in strollers, to ride in car seats, to stay in cribs and playpens or

188 CHAPTER 7 ■ The First Two Years: Psychosocial Development

Learning to Worship This boy in Borneo has learned that Allah is to be shown respect with a covered head and bare feet. He already prays five times a day as part of an ethnotheory that includes concepts of life and death, male and female, good and evil—just like everyone else in the world, although the specifics vary widely. R. I

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ethnotheory A theory that underlies the values and practices of a culture and that becomes apparent through analysis and comparison of those practices, although it is not usually apparent to the people within the culture.

➤Answer to Observation Quiz (from page 187): Out of 100 4-month-olds, 20 are fearful at least occasionally later in childhood, but only 5 are consistently fearful.

➤Response for Nurses and Pediatricians (from page 187): It’s too soon to tell. Tempera- ment is not truly “fixed” but variable, especially in the first few months. Many “difficult” infants become happy, successful adolescents and adults.

Especially for Parents of Young Adults U.S. culture includes the term empty nest, signifying an ethnotheory about mothers whose children live elsewhere. What cultural values are expressed by that term?

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Proximal and Distal Parenting Another example of ethnotheory involves how much parents should hold their infants. Proximal parenting involves being physically close to a baby, often hold- ing and touching. Distal parenting involves keeping one’s distance, providing toys, feeding by putting finger food within reach, and talking face to face instead of handling. Those who are convinced that one of these is right are expressing an ethnotheory.

A longitudinal study comparing child rearing among the Nso people of Cameroon, West Africa, and among Greeks in Athens found marked differences in proximal and distal parenting (H. Keller et al., 2004). The researchers video- taped 78 mothers as they played with their 3-month-old infants. Coders (who did not know the study’s hypothesis) rated the play as either proximal (e.g., carrying,

Theories About Infant Psychosocial Development 189

a case to study “Let’s Go to Grandma’s”

The ethnotheory of Mayan parents includes the belief that chil- dren should never be forced to comply with their parents’ wishes. When 18-month-old Roberto did not want to wear a diaper, his mother used a false promise, and then a distraction.

“Let’s put on your diaper . . . Let’s go to Grandma’s . . . We’re going to do an errand.” This did not work, and the mother invited Roberto to nurse, as she swiftly slipped the diaper on him with the father’s assistance. The father announced, “It’s over.”

[Rogoff, 2003, p. 204]

Lack of compliance by toddlers is a problem for many West- ern parents because their ethnotheory values independence, as Erikson recognized in the name he gave his second stage, auton- omy versus shame and doubt. Many Western parents battle with their autonomy-seeking 1-year-olds when the child’s self-will manifests itself in stubborn behavior. Yet the parents value inde- pendence, so they inadvertently encourage that emotion.

For instance, if a child refuses to get dressed, parents some- times force compliance by holding the child tight and pulling on clothes as the child cries and kicks. Or, if the room is warm and the child will stay inside, parents might give up and let the child remain half-dressed. Note that, in both cases, one person wins and the other loses, setting the emotional stage for another battle. Roberto’s mother chose neither option, even with

increasing exasperation that the child was wiggling and not standing to facilitate putting on his pants. Her voice softened as Roberto became interested in the ball, and she increased the stakes: “Do you want another toy?” They [father and mother] continued to try to talk Roberto into cooperating, and handed him various objects, which Roberto enjoyed. But still he stub-

bornly refused to cooperate with dressing. They left him alone for a while. When his father asked if he was ready, Roberto pouted “nono!”

After a bit, the mother told Roberto that she was leaving and waved goodbye. “Are you going with me?” Roberto sat quietly with a worried look. “Then put on your pants, put on your pants to go up the hill.” Roberto stared into space, seeming to consider the alternatives. His mother started to walk away, “OK then, I’m going. Goodbye.” Roberto started to cry, and his father persuaded, “Put on your pants then!” and his mother asked, “Are you going with me?”

Roberto looked down worriedly, one arm outstretched in half a take-me gesture. “Come on, then,” his mother offered the pants and Roberto let his father lift him to a stand and cooper- ated in putting his legs into the pants and in standing to have them fastened. His mother did not intend to leave; instead she suggested that Roberto dance for the audience. Roberto did a baby version of a traditional dance.

[Rogoff, 2003, p. 204]

This is an example of an ethnotheory that “elders protect and guide rather than giving orders or dominating” (Rogoff, 2003, p. 205). A second ethnotheory is apparent as well. Not only did the parents avoid dominating, they also used deception.

If a European American mother threatened to leave and then her child submitted, she probably would take him or her some- where, because North American ethnotheory holds that false threats lead children to doubt their parents. The bogeyman and Santa Claus are less often invoked by today’s educated parents than they were a few generations ago, more because of changed ethnotheory than because of new science.

behind gates. If toddlers do not lie down quietly to allow diapers to be changed (and few do), some parents simply hold the protesting child still while diapering. Compare this to the approach used by Roberto’s parents, below.

proximal parenting Parenting practices that involve close physical contact with the child’s entire body, such as cradling and swinging.

distal parenting Parenting practices that focus on the intellect more than the body, such as talking with the baby and playing with an object.

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swinging, caressing, exercising the child’s body) or distal (e.g., face-to-face talking) (see Table 7.2 and Research Design).

The Nso mothers were proximal parents, holding their babies all the time and almost never using objects. The Greek mothers were distal parents, using objects almost half the time and holding their babies less.

The researchers hypothesized that proximal parenting would result in toddlers who were less self-aware but more compliant—traits needed in an interdependent and cooperative society such as rural Cameroon. By contrast, distal parenting might result in toddlers who are self-aware but less obedient—traits needed in modern Athens, where independence, self-reliance, and competition are highly valued.

The predictions were accurate. At 18 months these children were tested on self- awareness (the rouge test) and compliance. The African toddlers didn’t recognize themselves in the mirror but obeyed; the opposite was true of the Greek children.

Replicating their own work, these researchers studied a dozen mother–infant pairs in Costa Rica, where play patterns and later toddler behavior were midway between those of the Nso and the Greeks. They then reanalyzed their original lon- gitudinal data, child by child. They found that proximal or distal play at 3 months was highly predictive of toddler behavior, even apart from culture. In other words, Greek mothers who, unlike most of their peers, were proximal parents had more obedient toddlers (H. Keller et al., 2004).

As this study suggested, every aspect of early emotional development interacts with cultural ideas of what is appropriate. For example, other research has found that separation anxiety is more evident in Japan than in Germany, because Japan- ese infants “have very few experiences with separation from the mother,” whereas in Germany “infants are frequently left alone outside of stores or supermarkets” while the mother shops (Saarni et al., 2006, p. 237). From the beginning of life, some emotions are dampened and others are fueled by family responses.

SUMMING UP

The five major theories differ in their explanations of the origins of early emotions and personality. Psychoanalytic theory stresses the mother’s responses to the infant’s needs for food and elimination (Freud) or for security and independence (Erikson). Behaviorism also stresses caregiving—especially as parents reinforce the behaviors they want their baby to learn or as they thoughtlessly teach unwanted behaviors.

Learning is also crucial in cognitive theory—not the moment-by-moment learning of behaviorism, but the infant’s self-constructed concept, or working model. Epigenetic

190 CHAPTER 7 ■ The First Two Years: Psychosocial Development

TABLE 7.2

Play Patterns in Rural Cameroon and Urban Greece

Amount of Time Spent in Play (percent)

Age of Babies Type of Play Nso, Cameroon Athens, Greece

3 months Held by mother 100 31

3 months Object play 3 40

Toddler Behavior Measured

18 months Self-recognition 3 68

18 months Compliance (without prompting) 72 2

Source: Adapted from Keller et al., 2004.

Research Design Scientists: A team of six from three nations (Germany, Greece, Costa Rica).

Publication: Child Development (2004).

Participants: A total of 90 mothers participated when their babies were 3 months old and again when they were 18 months old (32 from Cameroon, 46 from Greece, 12 from Costa Rica). In Greece and Costa Rica, researchers recruited mothers in hospitals. In Cameroon, permission was first sought from the local leader, and then announcements were made among local people.

Design: First, mothers played with their 3-month-olds, and that play was video- taped and coded for particular behav- iors. Fifteen months later, the toddlers’ self-recognition was assessed with the rouge test, and compliance with preset maternal commands was measured. The mother’s frequency of eye contact and body contact with the infant at 3 months was compared with the tod- dler’s self-awareness and compliance at 18 months.

Major conclusion:Toddlers with proxi- mal mothers were more obedient but less self-aware; toddlers with distal mothers tended to show the opposite pattern.

Comment:This is one of the best com- parison studies of child-rearing practices in various cultures. Families differed in income and urbanization; these variables need to be explored in other research.

Especially for Parents of Toddlers Your child refuses to stay in the car seat, spits out disliked foods, and almost never does what you say. What can you do?

➤Response for Parents of Young Adults (from page 188): The implication is that human mothers are like sad birds, bereft of their fledglings, who have flown away. Chapter 22 details the accuracy of this ethnotheory.

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theory begins with the inherited temperament and then describes how inborn tempera- ment is shaped. Sociocultural theory also sees an interaction between nature and nurture but emphasizes that the diversity of nurture explains much of the diversity of emotions. According to sociocultural theory, child-rearing practices arise from ethnothe- ories, unexpressed and implicit but very powerful.

■

The Development of Social Bonds All the theories of development agree that healthy human development depends on social connections, as you have already seen in the abnormal behavior of emo- tionally deprived Romanian orphans (Chapter 5), in the social exchanges required for language learning (Chapter 6), and in dozens of other examples. All the emo- tions already described elicit social reactions, and infants are happier and health- ier when others (especially their mothers) are nearby (Plutchik, 2003). Now we look closely at infant–caregiver bonds.

Synchrony Synchrony is a coordinated interaction between caregiver and infant, an exchange in which they respond to each other with split-second timing. Synchrony has been described as the meshing of a finely tuned machine (Snow, 1984), an emotional “attunement” of an improvised musical duet (Stern, 1985), and a smoothly flowing “waltz” (Barnard & Martell, 1995).

Detailed research reveals the mutuality of the interaction: Adults rarely smile at newborns until the infant smiles at them, at which point adults grin broadly and talk animatedly (Lavelli & Fogal, 2005). Since each baby has a unique temperament, parents must be sensitive to their particular infant (Feldman & Eidelman, 2005). Via synchrony, infants learn to read other emotions and to develop the skills of social interaction, such as taking turns and paying attention.

Although infants imitate adults, synchrony usually begins with parents imitating infants (Lavelli & Fogal, 2005). If parents detect an emotion from an infant’s expression (easy to do, because infant facial expressions and body motions reflect uni- versally recognizable emotions), and if an infant sees a familiar face expressing that emotion, the infant learns to connect an internal state with an external expression (Rochat, 2001).

For example, suppose an infant is unhappy. An adult who mirrors the distress, and then tries to solve the problem, will teach the infant that although unhappiness is a negative emotion, it is a valid one, and it can be relieved. Obviously, if the adult’s reaction to unhappiness is always to feed the infant, that might teach a destructive lesson (food equals comfort re- gardless of the cause of the distress). But if an adult’s reponse is more nuanced (by differentiating hunger, pain, boredom, or fear, for instance, and by responding differently to each), then the infant will learn to perceive the varied reasons for unhappiness and the varied ways of responding to it.

One of the important discoveries regarding synchrony is that adults do not merely echo infant emotions; they try to make them more positive. Thus, when their babies seem angry, mothers tend to react not with anger but with surprise (Malatesta et al., 1989).

synchrony A coordinated, rapid, and smooth exchange of responses between a care- giver and an infant.

The Development of Social Bonds 191

Dance with Me Synchrony in action, with each one’s hands, eyes, and open mouth reflecting the other’s expression. The close timing of synchrony has been compared to a waltz—and these partners look as if they never miss a beat.

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still-face technique An experimental practice in which an adult keeps his or her face un- moving and expressionless in face-to-face interaction with an infant.

Synchrony is experience-expectant, developing connections within the brain (Schore, 2001). For example, parents of triplets spend less time in synchrony with each of them than parents of single infants spend with their child (Feldman et al., 2004); perhaps for that reason, triplet cognition tends to be slightly delayed. Some mothers rarely play with their infants, and that slows down those children’s development (Huston & Aronson, 2005). Apparently, infant brains need social interaction to develop to their fullest. Babies usually elicit such interaction (as you have seen when a stranger makes faces to a baby in a public place), but some adults are too overwhelmed to play. In that case, the brain lacks an essential, expected stimulant.

Synchrony becomes more frequent and more elaborate as time goes on; a 6- month-old is a more responsive social partner than a 3-month-old. Parents and in- fants average about an hour a day in face-to-face play, although variations are apparent from baby to baby, from time period to time period, and from culture to culture (Baildam et al., 2000; Lee, 2000).

attachment According to Ainsworth, “an affectional tie” that an infant forms with the caregiver—a tie that binds them together in space and endures over time.

192 CHAPTER 7 ■ The First Two Years: Psychosocial Development

thinking like a scientist The Still-Face Technique

Is synchrony needed for normal development? If no one plays with an infant, how will that infant develop? Experiments using the still-face technique have addressed these questions (Tronick, 1989; Tronick et al., 1978). An infant is placed facing an adult, who plays with the baby while a video camera records each partner’s reactions. Frame-by-frame comparison of the two videotapes reveals the sequence. Typically, mothers synchronize their responses to the infants’ movements, usually with exagger- ated tone and expression, and babies reciprocate with smiles and arm waving.

Then, on cue, the adult erases all facial expression and stares with a “still face” for a minute or two. Not usually at 2 months, but clearly at 6 months, babies are very upset by the still face, especially from their parents (less so for strangers). Babies frown, fuss, drool, look away, kick, cry, or suck their fingers.

Interestingly, babies are much more upset when parents show a still face than when parents leave the room for a minute or two (Rochat, 2001). From a psychological perspective, this is healthy: It shows that “by 2 to 3 months of age, infants have begun to expect that people will respond positively to their initia-

tives” (R. A. Thompson, 2006, p. 29). In one set of experiments, infants became upset if someone had a still face for any reason— to look at a wall, to look at someone else, or merely to look away (Striano, 2004).

In another study, infants experienced not just one but two episodes of a parent’s still face. The infants quickly readjusted when their parent became responsive again if synchrony charac- terized the parent–infant relationship. If the parent was typi- cally unresponsive, however, infants stayed upset (with faster heart rate and more fussing) even after the second still-face episode ended (Haley & Stansbury, 2003).

Many research studies lead to the same conclusion: A parent’s responsiveness to an infant aids development, measured not only psychosocially but also biologically (with heart rate, weight gain, and brain maturation) (Moore & Calkins, 2004). If a mother is unresponsive to her infant (as usually happens with postpartum depression; see Chapter 4), the father or another caregiver should establish synchrony to help ensure normal development (Tronick & Weinberg, 1997).

Attachment Toward the end of the first year, face-to-face play almost disappears. Once infants can move around and explore, they are no longer content to stay in one spot and follow an adult’s facial expressions and vocalizations. Remember that, at about 12 months, most infants can walk and talk, which changes the rhythms of their social interaction (Jaffee et al., 2001). At this time a new type of connection, called attachment, replaces synchrony.

Attachment is a lasting emotional bond that one person has with another. Attachments form in infancy. According to attachment theory, new close relation- ships that arise later in life are influenced by these first attachments (R. A.

➤Response for Parents of Toddlers (from page 190): Remember the origins of the misbehavior—probably a combination of your child’s inborn temperament and your own distal parenting. Blended with your ethnotheory, all contribute to the child’s being stubborn and independent. Acceptance is more warranted than anger.

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Thompson & Raikes, 2003). In fact, adults’ attachment to their own parents, formed decades earlier, affects their relationships with their children. Humans learn in childhood how to relate to people, and those lessons echo lifelong (Gross- man et al., 2005; Sroufe et al., 2005).

When two people are attached, they respond to each other in particular ways. Infants show their attachment through proximity-seeking behaviors, such as approaching and following their caregivers, and through contact-maintaining behaviors, such as touching, snuggling, and holding. A securely attached toddler is curious and eager to explore but maintains contact by looking back at the caregiver.

Caregivers show attachment as well. They keep a watchful eye on their baby and respond sensitively to vocalizations, expressions, and gestures. For example, many mothers or fathers, awakening in the middle of the night, tiptoe to the crib to gaze fondly at their sleeping infant. During the day, many parents instinctively smooth their toddler’s hair or caress their child’s hand or cheek.

Over humanity’s evolutionary history, proximity-seeking and contact-maintaining behaviors contributed to the survival of the species (R. A. Thompson, 2006). Attachment keeps infants near their caregivers and keeps caregivers vigilant.

Secure and Insecure Attachment The concept of attachment was originally developed by John Bowlby (1969, 1973, 1988), a British developmentalist influenced by both psychoanalytic theory and ethology. Inspired by Bowlby’s work, Mary Ainsworth, then a young American graduate student, studied the relationship between par- ents and infants in Uganda (Ainsworth, 1973).

Ainsworth discovered that virtually all infants develop special attachments to their caregivers. Some infants are more securely attached than others—an observation later confirmed by hundreds of other researchers studying in dozens of nations and cultures (Cassidy & Shaver, 1999; Grossman et al., 2005; Sroufe, 2005; R. A. Thompson, 2006).

Attachment is classified into four types, labeled A–D (see Table 7.3). Infants with secure attachment (type B) feel comfortable and confident, The infant derives comfort from being close to the caregiver, and that provides him or her the confidence to ex- plore. The caregiver becomes a base for exploration, giving the child the assurance to venture forth. A toddler might, for example,

The Development of Social Bonds 193

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secure attachment A relationship in which an infant obtains both comfort and confidence from the presence of his or her caregiver.

Learning Emotions Infants respond to their parents’ expressions and actions. If the moments shown here are typical, one young man will be happy and outgoing and the other will be sad and quiet.

Observation Quiz (see answer, page 194): For the pair on the left, where are their feet?

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scramble down from the caregiver’s lap to play with a toy but periodically look back, vocalize a few syllables, and return for a hug.

By contrast, insecure attachment (types A and C) is characterized by fear, anxi- ety, anger, or indifference. Insecurely attached children have less confidence. Some play without maintaining contact with the caregiver; this is insecure-avoidant attachment (type A). An insecurely attached child might instead be unwilling to leave the caregiver’s lap; this is insecure-resistant/ambivalent attachment (type C).

The fourth category (type D) is called disorganized attachment; it may have some elements of any of the other types, but it is clearly different from them. Type D infants may shift from hitting to kissing their mothers, from staring blankly to crying hysterically, from pinching themselves to freezing in place.

About two-thirds of all infants are securely attached (type B). Their mother’s presence gives them courage to explore. The father’s presence makes some infants even more confident. The caregiver’s departure may cause distress; the caregiver’s return elicits positive social contact (such as smiling or hugging) and then more playing. A balanced reaction—being concerned about the caregiver’s departure but not overwhelmed by it—reflects secure attachment.

Almost a third of all infants are insecure, appearing either indifferent (type A) or unduly anxious (type C). The remaining infants fit into none of these categories and are classified as disorganized (type D).

Measuring Attachment Ainsworth (1973) developed a now-classic laboratory procedure, called the Strange Situation, to measure attachment. In a well-equipped playroom, an infant is closely observed for eight episodes, during which the infant is with the caregiver (usually the mother), with a stranger, with both, or alone.

First, the caregiver and child are together. Then every three minutes the stranger or the caregiver enters or leaves the playroom. Infants’ responses to the stress of caregiver departure and stranger presence indicate which type of attach- ment they have formed to their caregivers. For research purposes, observers are carefully trained and are certified when they are able to accurately differentiate types A, B, C, and D. The key aspects to focus on are the following:

■ Exploration of the toys. A securely attached toddler plays happily. ■ Reaction to the caregiver’s departure. A secure toddler misses the caregiver. ■ Reaction to the caregiver’s return. A secure toddler welcomes the caregiver.

insecure-avoidant attachment A pattern of attachment in which an infant avoids con- nection with the caregiver, as when the infant seems not to care about the care- giver’s presence, departure, or return.

insecure-resistant/ambivalent attachment A pattern of attachment in which anxiety and uncertainty are evident, as when an infant is very upset at separation from the caregiver and both resists and seeks con- tact on reunion.

disorganized attachment A type of attach- ment that is marked by an infant’s inconsistent reactions to the caregiver’s departure and return.

194 CHAPTER 7 ■ The First Two Years: Psychosocial Development

TABLE 7.3

Patterns of Infant Attachment

Name of Toddlers in Type Pattern In Play Room Mother Leaves Mother Returns Category (percent)

A

B

C

D

Insecure-avoidant

Secure

Insecure-resistant/ ambivalent

Disorganized

Child plays happily

Child plays happily

Child clings, is preoccupied with mother

Child is cautious

Child continues playing

Child pauses, is not as happy

Child is unhappy, may stop playing

Child may stare or yell; looks scared, confused

Child ignores her

Child welcomes her, returns to play

Child is angry, may cry, hit mother, cling

Child acts oddly— may freeze, scream, hit self, throw things

10–20

50–70

10–20

5–10

Strange Situation A laboratory procedure for measuring attachment by evoking infants’ reactions to stress.

➤Answer to Observation Quiz (from page 193): The father uses his legs and feet to support his son at just the right distance for a great fatherly game of foot-kissing.

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[It is reactions to the caregiver that indicate attachment; reactions to strangers (whether tears or signs of interest) are a matter of temperament more than of affectional bond.]

Attachment is not always measured via the Strange Situation, which requires that infants be assessed one by one in a laboratory by carefully trained researchers. Sometimes attachment is measured via 90 questions to be sorted by parents about their children or via an extensive interview with parents about their relationships with their own parents. All these measures find a correlation between secure attachment and desirable personality traits and cognitive development. All also find that the type of attachment changes when circumstances (such as the re- sponsiveness of the mother) change. Many aspects of good parenting correlate with secure attachment (see Table 7.4).

The Development of Social Bonds 195

The Attachment Experiment In this episode of the Strange Situation, Brian shows every sign of secure attachment. (a) He explores the playroom happily when his mother is present; (b) he cries when she leaves; and (c) he is readily comforted when she returns.

(a) (b) (c)

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These family and infant characteristics influence a child’s attachment status in the ways stated here, but none fully determine it. For example, parental sensitivity predicts only a modest amount of the variation between secure and insecure children. All these correlations have been found in several studies, but none appear in every study, because infant temperaments, contexts, and cultures vary too much.

TABLE 7.4

Predictors of Attachment Type

Secure attachment (type B) is more likely if:

■ The parent is usually sensitive and responsive to the infant’s needs.

■ The infant–parent relationship is high in synchrony.

■ The infant’s temperament is “easy.”

■ The parents are not stressed about income, other children, or their marriage.

■ The parents have a working model of secure attachment to their own parents.

Insecure attachment is more likely if: ■ The parent mistreats the child. (Neglect increases type A; abuse increases C and D.)

■ The mother is mentally ill. (Paranoia increases type D; depression increases type C.)

■ The parents are highly stressed about income, other children, or their marriage. (Parental stress increases types A and D.)

■ The parents are intrusive and controlling. (Parental domination increases type A.)

■ The parents are active alcoholics. (Alcoholic father increases type A; alcoholic mother increases type D.)

■ The child’s temperament is “difficult.” (Difficult children tend to be type C.)

■ The child’s temperament is “slow to warm up.” (This correlates with type A.)

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Insecure Attachment and Social Setting Early researchers expected secure attachment to “predict all the outcomes rea- sonably expected from a well-functioning personality” (R. A. Thompson & Raikes, 2003, p. 708). But this turned out not to be the case. Securely attached infants are more likely to become secure toddlers, socially competent preschoolers, aca- demically skilled schoolchildren, and better parents (R. A. Thompson, 2006). However, the correlations are not large, and that makes prediction very tentative. Many children shift in attachment status between one age and another (NICHD, 2001; Seifer et al., 2004).

The most troubled children may be those who are classified as type D. If their disorganization makes them unable to develop an effective strategy for dealing with other people (even an avoidant or resistant strategy, type A or C), they may lash out. Sometimes they become hostile and aggressive, difficult for anyone else to relate to (Lyons-Ruth et al., 1999). (An unusually high percentage of the Romanian children who were adopted after age 2 were type D.)

Social Referencing Infants seek to understand caregivers’ emotions. At about age 1, social referencing becomes evident when an infant looks to another person for clarification or infor- mation, much as someone might consult a dictionary or other “reference” work. A glance of reassurance or words of caution, an expression of alarm, pleasure, or dismay—each becomes a social guide, telling an infant how to react to an unfamil- iar situation.

After age 1, when infants reach the stage of active exploration (Piaget) and the crisis of autonomy versus shame and doubt (Erikson), the need to consult care- givers becomes urgent. Toddlers search for cues in gaze and facial expressions, pay

close attention to adults’ expressed emotions, and watch carefully to de- tect intentions behind other people’s actions (Baldwin, 2000).

Social referencing has many practical applications. Consider meal- time. Caregivers the world over smack their lips, pretend to taste, and say “yum-yum,” encouraging toddlers to eat and enjoy their first beets, liver, or spinach. For their part, toddlers become astute at reading expres- sions, insisting on the foods that the adults really like. Through this process, children in some cultures develop a taste for raw fish or curried goat or smelly cheese—foods that children in other cultures refuse.

Referencing Mothers Most everyday instances of social referencing occur with mothers. In- fants usually heed their mother’s wishes, expressed in tone and facial ex- pression. This does not mean that infants are always obedient, especially in cultures where parents and children value independence. Not surpris- ingly, compliance has been the focus of study in the United States, where it often conflicts with independence.

For example, in one experiment, few toddlers obeyed their mother’s request (required by the researchers) to pick up dozens of toys that they had not scattered (Kochanska et al., 2001). Their refusal indicates some emotional maturity: Self-awareness had led to pride and autonomy. The

body language and expressions of some of the mothers implied that they did not really expect their children to obey.

These same toddlers were quite obedient when their mothers told them not to touch an attractive toy. The mothers used tone, expression, and words to make this prohibition clear. Because of social referencing, toddlers understood the

social referencing Seeking information about how to react to an unfamiliar or ambiguous object or event by observing someone else’s expressions and reactions. That other person becomes a social reference.

196 CHAPTER 7 ■ The First Two Years: Psychosocial Development

Social Referencing Should I be happy or scared to ride on a bicycle through the streets of Osaka, Japan? Check with Mom to find out.

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Especially for Grandmothers A grand- mother of an infant boy is troubled that the baby’s father stays with him whenever the mother is away. She says that men don’t know how to care for infants, and she notes that he sometimes plays a game in which he tosses his son in the air and then catches him.

message. Even when the mothers were out of sight, half of the 14-month-olds and virtually all of the 22-month-olds obeyed. Most (80 percent) of the older toddlers seemed to agree with the mothers’ judgment (Kochanska et al., 2001).

Referencing Fathers In North America, increases in maternal employment have expanded the social references available to infants. Fathers—once thought to be uninvolved with their infants (as was the case with Uncle Henry)—now spend considerable time with their children.

For example, the stereotype is that Latino fathers leave caregiving to their wives. However, a study of more than 1,000 Latino 9-month-olds found “fathers with moderate to high levels of engagement” (Cabrera et al., 2006. p. 1203). Although many possible correlates of father involvement (income, education, age) were analyzed, only one significant predictor of the level of engagement was found: how happy the father was with the infant’s mother. Happier husbands tend to be more involved fathers.

The social information that infants get from their fathers tends to be more en- couraging than that from mothers, who are more cautious and protective. When toddlers are about to explore, they often seek their father’s approval, expecting fun from their fathers and comfort from their mothers (Lamb, 2000; Parke, 1996).

In this, infants show social intelligence, because fathers play imaginative and exciting games. They move their infant’s legs and arms in imitation of walking, kicking, or climbing; or play “airplane,” zooming the baby through the air; or tap and tickle the baby’s stomach. Mothers caress, murmur, read, or sing soothingly; combine play with caretaking; and use standard sequences such as peek-a-boo and patty-cake. In short, fathers are generally more proximal, engaging in play that involves the infant’s whole body.

Infant Day Care You have seen that social bonds are crucial for infants. How is this need affected by time spent with paid caregivers? More than half of all 1-year-olds in the United States are in “regularly scheduled” nonmaternal care, sometimes by relatives (usu- ally the father or grandmother) but often not (Loeb et al., 2004). Mothers usually prefer care by a relative because it is the least expensive, often free. However, family care varies in quality and availability. (If a mother is employed, chances are her husband and mother are as well.)

Family day care (children of various ages cared for in someone else’s home) is more often used for infants, and older children are more often in center day care (several paid caregivers in a place designed for young children). Quality varies in such places, with standards varying markedly from state to state as well as from nation to nation.

In the United States, most parents encounter a “mix of quality, price, type of care, and government subsidies” (Haskins, 2005, p. 168). Some center care is excellent (see Table 7.5), with adequate space, equipment, and trained providers (the ratio of adults to infants should be about 2:5), but it is hard to find. House- holds with higher incomes are more likely to use center care. In other nations, people of all incomes use center care, funded by the government.

The evidence is overwhelming that good preschool education (reviewed in Chapter 9) is beneficial for young children. Infant day care is more controversial (Waldfogel, 2006), but most developmentalists find that infants are not likely to be harmed by—and, in fact, can benefit from—professional day care (Brooks- Gunn et al., 2002; Lamb, 1998).

The Development of Social Bonds 197

family day care Child care that occurs in another caregiver’s home. Usually the caregiver is paid at a lower rate than in center care, and usually one person cares for several children of various ages.

center day care Child care in a place espe- cially designed for the purpose, where several paid providers care for many chil- dren. Usually the children are grouped by age, the day-care center is licensed, and providers are trained and certified in child development.

Up, Up, and Away! The vigorous play typical of fathers is likely to help in the infant’s mas- tery of motor skills and the development of muscle control.

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A longitudinal study has followed the development of more than 1,300 children from birth to age 11 (NICHD, 2005). The effects of various types of infant care on attachment was a major concern of the researchers, but most analyses of the data found that attachment to the mother is as secure among infants in center care as among infants cared for at home. Like other, smaller studies, this NICHD study confirms that infant day care, even for 40 hours a week before age 1, has much less influence on child development than does the warmth of the mother–infant relationship. Infant and child cognition, especially language learning, advance with center care (NICHD, 2005; see Research Design).

Good infant day care is expensive and scarce, however, because infants need individualized and affectionate attention, which are likely to be in short supply if a caregiver has many infants to care for and limited experience and training (Waldfogel, 2006). Probably for this reason, “disagreements about the wisdom (indeed, the morality) of nonmaternal child care for the very young remain” (NICHD, 2005, p. xiv).

No study finds that children of employed mothers suffer solely because their mothers are working. Many employed mothers make infant care their top priority. For example, time-use research finds that mothers who work full time outside the home spend almost as much time playing with their babies (141⁄2 hours a week) as do mothers without outside jobs (16 hours a week) (Huston & Aronson, 2005). Employed mothers spend half as much time on housework and almost no time on leisure. The study concludes:

There was no evidence that mothers’ time at work interfered with the quality of their relationship with their infants, the quality of the home environment, or children’s development. In fact, the results suggest the opposite. Mothers who spent more time at work provided slightly higher quality home environments.

[Huston & Aronson, 2005, p. 479]

Other research confirms that much depends on the quality of care, wherever it occurs and whoever provides it. According to the NICHD Early Child Care Research Network, early day care seems detrimental only when the mother is in-

Especially for Day-Care Providers A mother who brings her child to you for day care says that she knows she is harming her baby but must work out of economic necessity. What do you say?

198 CHAPTER 7 ■ The First Two Years: Psychosocial Development

TABLE 7.5

High-Quality Day Care

High-quality day care during infancy has five essential characteristics:

1. Adequate attention to each infant. This means a low caregiver-to-infant ratio and, probably even more important, a small group of infants. The ideal situation might be two reliable caregivers for five infants. Infants need familiar, loving caregivers; continuity of care is very important.

2. Encouragement of language and sensorimotor development. Infants should receive extensive language exposure through games, songs, conversations, and positive talk of all kinds, along with easily manipulated toys.

3. Attention to health and safety. Cleanliness routines (e.g., handwashing before meals), accident prevention (e.g., no small objects that could be swallowed), and safe areas for exploration (e.g., a clean, padded area for crawling and climbing) are good signs.

4. Well-trained and professional caregivers. Ideally, every caregiver should have a degree or certificate in early-childhood education and should have worked with children for several years. Turnover should be low, morale high, and enthusiasm evident. Good caregivers love their children and their work.

5. Warm and responsive caregivers. Providers should engage the children in problem solving and discussions, rather than giving instructions. Quiet, obedient children may be an indication of unresponsive care.

For a more detailed evaluation of day care, see the checklist in NICHD, 2005.

Research Design Scientists: NICHD Early Child Care Research Network, 30 developmental- ists cooperating in a study sponsored by the National Institute of Child Health and Human Development (NICHD) .

Publication: Hundreds of research arti- cles in every major child developmental journal and a book, Child Care and Child Development (2005), have been pub- lished analyzing these data.

Participants:Total of 1,364 mother– infant pairs, from 25 hospitals at 10 sites throughout the United States. Partici- pants were recruited within days after birth. Participating mothers had to be over 18, English-speaking, and healthy.

Design: Ongoing longitudinal study, with many repeated measures from birth to age 10, looking especially at child-care arrangements and at social, emotional, and cognitive development. The data from this study have been used for many purposes; here we focus on correlations between infant care and later development.

Major conclusions: Quality of maternal care is more important than specifics of care. Poor-quality day care, especially in infancy, has some long-term negative effects. Some researchers have found that nonmaternal care for 40 or more hours per week increases the risk of later aggression.

Comment:This study is large, diverse, and ongoing, and it continues to pro- vide fascinating results. One strength is that many regions within the United States were sampled; one weakness is that only one nation was studied.The main drawback is that low-SES and im- migrant mothers are not adequately represented.

➤Response for Grandmothers (from page 197): Fathers can be great caregivers, and most mothers prefer that the father provide care. It’s good for the baby and the marriage. Being tossed in the air is great fun (as long as the father is careful and a good catcher!). A generation or two ago, mothers seldom let fathers care for infants. Fortunately, today’s mothers are less likely to act as gatekeepers, shutting the fathers out.

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sensitive and the infant spends more than 20 hours a week in a poor- quality program in which there are too few caregivers, with too little training) (NICHD, 2005).

Although the mother’s sensitivity is the best predictor of a child’s social skills, day care can have a significant effect, too. Some children, espe- cially boys, who receive extensive nonmaternal care are more quarrel- some and have more conflicts with their teachers than does the average student (NICHD, 2003).

The negative effects of poor care have also been found in a study in Israel of 758 infants. Those cared for at home by an attentive father or grandmother seemed to do very well, as did those in a high-quality day- care center. However, those cared for in a center with untrained care- givers and only one adult for five infants fared poorly (Sagi et al., 2002). Other studies also find that a 5:1 ratio of infants to adults is too high; 5:2 not only allows caregivers to provide better instruction and support but also makes children more cooperative (de Schipper et al., 2006).

Regarding home care, children whose primary caregiver is depressed fare worse than they would in center care (Loeb et al., 2004). Many studies find that out-of-home day care is better than in-home care if an infant’s family does not provide adequate stimulation and attention (Ramey et al., 2002; Votruba-Drzal et al., 2004).

Among the benefits of day care is the opportunity to learn to express emotions. When a toddler is temperamentally very shy or aggressive, he or she is less likely to remain so if caregivers and other children are available as social references (Fox et al., 2001; Zigler & Styfco, 2001). But no expert would say that all infants are better off either in day care or at home.

SUMMING UP

Infants seek social bonds, which they develop with one or several people. Synchrony begins in the early months: Infants and caregivers interact face to face, making split- second adjustments in their emotional responses to each other. Synchrony evolves into attachment, an emotional bond with adult caregivers. Secure attachment allows learning to progress; insecure infants are less confident and may develop emotional impairments. As infants become more curious and as they encounter new toys, people, and events, they use social referencing to learn whether such new things are fearsome or fun.

The emotional connections evident in synchrony, attachment, and social referencing may occur with mothers, fathers, other relatives, and day-care providers. Instead of harming infants, as was once feared, nonmaternal care sometimes enhances infants’ psychosocial development. The quality and continuity of child care matter more than who provides it.

■

Conclusions in Theory and Practice You have seen in this chapter that the first two years are filled with psychosocial interactions, all of which result from genes, maturation, culture, and caregivers. Each of the five major theories seems plausible. No single theory stands out as the best.

All theorists agree that the first two years are crucial, with early emotional and social development influenced by the parents’ behavior, the quality of day care, cultural patterns, and inborn traits. It has not been proven whether one influence, such as a good day-care center, compensates for another, such as a depressed mother (although parental influence is always significant). Multicultural research

Especially for Potential Day-Care Providers What are some of the benefits and costs of opening and running a day-care center?

Conclusions in Theory and Practice 199

Secure Attachment Kirstie and her 10- month-old daughter Mia enjoy a moment of synchrony in an infant day-care center spon- sored by a family-friendly employer, General Mills. High-quality day care and high-quality home care are equally likely to foster secure attachment between mother and infant.

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has identified a wide variety of practices in differ- ent societies. These discoveries imply that no one event (such as toilet training, in Freud’s theory) determines emotional health.

On the basis of what you have learned, you could safely advise parents to play with their in- fants; respond to their physical and emotional needs; let them explore; maintain a relationship; pay attention to them; and expect every toddler to be sometimes angry, sometimes proud, sometimes fearful. Parental actions and attitudes may or may not have a powerful impact on later development, but they certainly can make infants happier or sad- der. Parental attentiveness leads to synchrony, at- tachment, and social referencing, which are crucial to infant and toddler development.

Such generalities are not good enough for Jacob, or for all the other infants who show signs of malnutrition, delayed language, poor social skills, abnormal emotional development, insecure or disorganized attachment, or other deficits. In dealing with individual children who have prob- lems, we need to be more specific.

Jacob was 3 years old but not talking. Even in his first year, his psychosocial development was impaired. Looking at Table 7.6 on infant develop- ment, you can see that even at 3 months he was unusual in his reaction to familiar people. All in- fants need one or two people who are emotionally invested in them from the first days of life, and it is not clear that Jacob had anyone, including his nanny, who did not speak English, or his parents. There is no indication of synchrony or attachment.

Something had to be done, as the parents even- tually realized. They took Jacob for evaluation at a major teaching hospital. He was seen by at least

10 experts, none of whom said anything encouraging. The diagnosis was “pervasive developmental disorder,” which suggests serious brain abnormality.

Fortunately, Jacob’s parents then consulted a psychiatrist who specialized in chil- dren with psychosocial problems (Greenspan & Wieder, 2003). He showed them how to relate to Jacob, saying, “I am going to teach you how to play with your son.” They learned about “floor time,” four hours a day set aside to get on their son’s level and interact: Imitate him, act as if they are part of the game, put their faces and bodies in front of his, create synchrony even though Jacob did not initiate it.

The father reports:

We rebuilt Jacob’s connection to us and to the world—but on his terms. We were drilled to always follow his lead, to always build on his initiative. In a sense, we could only ask Jacob to join our world if we were willing to enter his. . . . He would drop rocks and we would catch them. He would want to put pennies in a bank and we would block the slot. He would want to run in a circle and we would get in his way.

I remember a cold fall day when I was putting lime on our lawn. He dipped his hand in the powder and let it slip through his fingers. He loved the way it

200 CHAPTER 7 ■ The First Two Years: Psychosocial Development

TABLE 7.6

AT ABOUT THIS TIME: Infancy

Approximate Age Characteristic or Achievement

3 months Rolls over Stays half-upright in stroller Uses two eyes together Grabs for object; if rattle in hand, can shake it Makes cooing noises Joyous recognition of familiar people

6 months Sits up, without adult support (but sometimes using arms) Grabs and can grasp objects with whole hand Smiles and laughs Babbles, listens, and responds with facial expression Tries to crawl (on belly, not yet on all fours) Stands and bounces with support

(on someone’s lap, in a bouncer) Begins to shows signs of anger, fear, attachment

12 months Stands without holding on Crawls well Takes a few unsteady steps Uses fingers, including pincer grasp (thumb and forefingers) Can feed self with fingers Speaks a few words (mama, dada, baba) Strong attachment to familiar caregivers Apparent fear of strangers, of unexpected noises and events

18 months Walks well Runs, but also falls Tries to climb on furniture Speaks 50–100 words; most are nouns Begins toilet training Likes to drop things, throw things, take things apart Recognizes self in mirror

24 months Runs well Climbs up (down is harder) Uses simple tools (spoon, large marker) Combines words (usually noun/verb,

sometimes noun/verb/noun) Can use fingers to unscrew tops, open doors Very interested in new experiences and new children

An Eventful Time This table lists aspects of development that have been discussed in Chapters 5, 6, and 7. Throughout infancy, tem- perament and experience affect when and how babies display the characteristics and achievements listed here. The list is meant as a rough guideline, not as a yardstick for indi- cating a child’s progress in intelligence or any other trait.

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Emotional Development 1. Two emotions, contentment and distress, appear as soon as an infant is born. Anger emerges with restriction and frustration, between 4 and 8 months of age, and becomes stronger by age 1.

2. Reflexive fear is apparent in very young infants. However, fear of something specific, including fear of strangers and fear of sepa- ration, does not appear until toward the end of the first year.

3. In the second year, social awareness produces more selective fear, anger, and joy. As infants become increasingly self-aware at about 18 months, emotions—specifically, pride, shame, and affection—emerge that encourage an interface between the self and others.

Theories About Infant Psychosocial Development 4. According to all five major theories, caregiver behavior is espe- cially influential in the first two years. Freud stressed the mother’s impact on oral and anal pleasure; Erikson emphasized trust and autonomy.

5. Behaviorists focus on learning; parents teach their babies many things, including when to be fearful or joyful. Cognitive

theory holds that infants develop working models based on their experiences.

6. Epigenetic theory emphasizes temperament, a set of genetic traits whose expression is influenced by the environment. Parental practices inhibit and guide a child’s temperament, but they do not create it. Ideally, a good fit develops between the parents’ actions and the child’s personality.

7. The sociocultural approach notes the impact of social and cultural factors on the parent–infant relationship. Ethnotheories shape infant emotions and traits so that they fit well within the culture. Some cultures encourage proximal parenting (more physical touch); others promote distal parenting (more talk and object play).

The Development of Social Bonds 8. By 3 months, infants become more responsive and social, and synchrony begins. Synchrony involves moment-by-moment inter- action. Caregivers need to be responsive and sensitive. Infants are disturbed by a still face because they expect and need social interaction.

SUMMARY

felt. I took the lawn spreader and ran to the other part of our yard. He ran after me. I let him have one dip and ran across the yard again. He dipped, I ran, he dipped, I ran. We did this until I could no longer move my arms.

[Jacob’s father, 1997, p. 62]

Jacob’s case is obviously extreme, but many infants and parents have difficulty establishing synchrony. From the perspective of early psychosocial development, nothing could be more important than a connection like the one Jacob and his parents established.

In Jacob’s case it worked. He said his first word at age 3, and by age 5 . . . he speaks for days at a time. He talks from the moment he wakes up to the moment he falls asleep, as if he is making up for lost time. He wants to know everything. “How does a live chicken become an eating chicken? Why are microbes so small? Why do policemen wear badges? Why are dinosaurs extinct? What is French? [A question I often ask myself.] Why do ghosts glow in the dark?” He is not satisfied with answers that do not ring true or that do not satisfy his standards of clarity. He will keep on asking until he gets it. Rebecca and I have become expert definition providers. Just last week, we were faced with the ultimate challenge: “Dad,” he asked: “Is God real or not?” And then, just to make it a bit more chal- lenging, he added: “How do miracles happen?”

[Jacob’s father, 1997, p. 63]

Miracles do not always happen. Children with pervasive developmental disor- der usually require special care throughout childhood; Jacob may continue to need extra attention. Nevertheless, almost all infants, almost all the time, develop strong relationships with their close family members. The power of early psycho- social development is obvious to every developmentalist and, it is hoped, to every reader of this text.

Summary 201

➤Response for Potential Day-Care Providers (from page 199): A high-quality day-care center needs trained and responsive adults and a clean, safe space—all of which can be expensive and may mean that you will have to charge higher fees than many families can afford to pay. The main benefit for you is knowing that you can make a major contribution to the well-being of infants and their families.

➤Response for Day-Care Providers (from page 198): Reassure the mother that you will keep her baby safe and will help to develop the baby’s mind and social skills by fostering synchrony and attachment. Also tell her that the quality of mother–infant interaction at home is more important than anything else for psychosocial development; mothers who are employed full time usually have wonderful, secure relationships with their infants. If the mother wishes, you can discuss ways she can be a more responsive mother.

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7. Why would a mother and father choose not to care for their infant themselves, 24/7?

8. What are the advantages and disadvantages of three kinds of nonmaternal infant care: relatives, family day care, and center day care?

9. Attachments are said to be lifelong. Describe an adult who is insecurely attached.

10. How would psychosocial development be affected if an infant spent every day in a crowded day-care center—for example, a center with eight infants for every caregiver?

11. In terms of infant development, what are the differences be- tween employed and unemployed mothers?

1. How would a sensitive parent respond to an infant’s distress?

2. How do emotions in the second year of life differ from emotions in the first year?

3. What are similarities and differences in the two psychoanalytic theories of infancy?

4. How might synchrony affect the development of emotions in the first year?

5. What is an example of an ethnotheory of your culture that dif- fers from those of other cultures?

6. What are the similarities between epigenetic and sociocultural theories of infant emotions?

infant is available, observe a pair of lovers as they converse. Note the sequence and timing of every facial expression, sound, and gesture of both partners.

3. Telephone several day-care centers to try to assess the quality of care they provide. Ask about such factors as adult–child ratio, group size, and training for caregivers of children of various ages. Is there a minimum age? If so, why was that age chosen? Analyze the answers, using Table 7.5 as a guide.

1. One cultural factor influencing infant development is how infants are carried from place to place. Ask four mothers whose infants were born in each of the past four decades how they trans- ported them—front or back carriers, facing out or in, strollers or carriages, car seats or on mother’s laps, and so on. Why did they choose the mode(s) they chose? What are their opinions and yours on how that cultural practice might affect infants’ development?

2. Observe synchrony for three minutes. Ideally, ask the parent of an infant under 8 months of age to play with the infant. If no

KEY QUESTIONS

APPLICATIONS

202 CHAPTER 7 ■ The First Two Years: Psychosocial Development

social smile (p. 180) stranger wariness (p. 181) separation anxiety (p. 181) self-awareness (p. 182) trust versus mistrust (p. 183) autonomy versus shame and

doubt (p. 184) social learning (p. 184)

working model (p. 184) temperament (p. 185) goodness of fit (p. 187) ethnotheory (p. 188) proximal parenting (p. 189) distal parenting (p. 189) synchrony (p. 191) still-face technique (p. 192)

attachment (p. 192) secure attachment (p. 193) insecure-avoidant attachment

(p. 194) insecure-resistant/ambivalent

attachment (p. 194) disorganized attachment

(p. 194)

Strange Situation (p. 194) social referencing (p. 196) family day care (p. 197) center day care (p. 197)

KEY TERMS

9. Attachment, measured by the baby’s reaction to the caregiver’s presence, departure, and return in the Strange Situation, is crucial. Some infants seem indifferent (type A—insecure-avoidant) or overly dependent (type C—insecure-resistant/ambivalent), instead of secure (type B). Disorganized attachment (type D) is the most worrisome form.

10. Secure attachment provides encouragement for infant explo- ration. As they play, toddlers engage in social referencing, looking to other people’s facial expressions to detect what is fearsome and what is enjoyable.

11. Fathers are wonderful playmates for infants, who frequently consult them, as well as their mothers, as social references.

12. Day care for infants seems, on the whole, to be a positive experience, especially for cognitive development. Psychosocial characteristics, including secure attachment, are influenced more by the mother’s warmth than by the number of hours spent in nonmaternal care. Quality of care is crucial, no matter who pro- vides that care.

Conclusions in Theory and Practice 13. Experts debate exactly how critical early psychosocial devel- opment may be: Is it the essential foundation for all later growth or just one of many steps along the way? However, all infants need caregivers who are committed to them and are dedicated to encouraging each aspect of early development.

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The First Two Years PA R T I I

BIOSOCIAL Body Changes Over the first two years, the body quadruples in weight and the brain triples in weight. Connections between brain cells grow increasingly dense, with com- plex neural networks of dendrites and axons. Neurons become coated with an insulat- ing layer of myelin, sending messages faster and more efficiently, and the various states—sleeping, waking, exploring—become more distinct. Experiences that are uni- versal (experience-expectant) and culture-bound (experience-dependent) both aid brain growth, partly by allowing pruning of unused connections between neurons.

Senses and Motor Skills Brain maturation underlies the development of all the senses. Seeing, hearing, and mobility progress from reflexes to coordinated voluntary actions, including focusing, grasping, and walking. Culture is evident in sensory and motor development, as brain networks respond to the particulars of each infant’s life.

Public Health Infant health depends on immunization, parental practices (including “back to sleep”), and nutrition (ideally, breast milk). Survival rates are much higher today than they were even a few decades ago, yet in some regions of the world infant growth is still stunted because of malnutrition.

COGNITIVE Sensorimotor Intelligence and Information Processing As Piaget describes it, during the first two years (sensorimotor intelligence) infants progress from knowing their world through immediate sensory experiences to being able to “experiment” on that world through actions and mental images. Information-processing theory stresses the links be- tween input (sensory experiences) and output (perception). Infants develop affordances, their own ideas regarding the possibilities offered by the objects and events of the world. Recent research finds traces of memory at 3 months, object permanence at 4 months, and deferred imitation at 9 months—all much younger ages than Piaget described.

Language Interaction with responsive adults exposes infants to the structure of com- munication and thus language. By age 1, infants can usually speak a word or two; by age 2, language has exploded, as toddlers talk in short sentences and add vocabulary words each day. Language develops through reinforcement, neurological maturation, and social motivation.

PSYCHOSOCIAL Emotions and Theories Emotions develop from basic newborn reactions to complex, self-conscious responses. Infants’ increasing self-awareness and independence are shaped by parents, in a transition explained by Freud’s oral and anal stages, by Erikson’s crises of trust versus mistrust and autonomy versus shame and doubt, by behaviorism in the focus on parental responses, and by cognitive theory’s working models. Much of basic temperament—and therefore personality—is inborn and apparent throughout life, as epigenetic theory explains. Sociocultural theory stresses cultural norms, evident in parents’ ethnotheories that guide them in raising their infants.

The Development of Social Bonds Early on, parents and infants respond to each other by synchronizing their behavior in social play. Toward the end of the first year, secure attachment between child and parent sets the stage for the child’s increasingly independent exploration of the world. Insecure attachment—avoidant, resistant, or disorganized—signifies a parent–child relationship that hinders infant learning. Infants become active participants in social interactions. Fathers and day-care providers, as well as mothers, encourage infants’ social confidence.

The Developing Person So Far:

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The Play Years

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CHAPTER 8

CHAPTER 9

CHAPTER 10

T he years from age 2 to age 6 are often

called early childhood or the preschool

period. In this book we also call them the

play years. People of all ages play, of

course, but this is prime time. During early child-

hood, children spend most of their waking hours

discovering, creating, laughing, and imagining as

they acquire the skills they will need. They chase

each other and attempt new challenges (developing

their bodies); they play with sounds, words, and

ideas (developing their minds); they invent games

and dramatize fantasies (learning social skills and

moral rules).

Playfulness makes young children exasperating

as well as delightful. To them, growing up is a game,

and their enthusiasm for it seems unlimited—

whether they are quietly tracking a beetle through

the grass or riotously turning their bedroom into a

shambles. Their minds seem playful, too, when they

explain that “a bald man has a barefoot head” or

that “the sun shines so children can go outside to

play.”

If you expect young children to sit quietly or

think logically, you’ll be disappointed. But if you

enjoy play, then these children will bring you joy.

PA R T I I I

205

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The Play Years: Biosocial Development

When you were 3 years old, I hope you wanted to fly like a bird,a plane, or Superman, and I hope someone kept you safe.Protection is needed, as well as appreciation of this period ofdevelopment. Do you remember learning to skip or to write your name? Three-year-olds try all these, but they shuffle instead of skip, and they forget letters of the alphabet. By age 6, they can skip, write, and much more, as long as they have had enough practice.

Thus, not only do children grow bigger and stronger, they also become more skilled at hundreds of tasks. These advances and the need to protect children against serious problems that sometimes occur, are themes of this chapter.

Body Changes Compared with cute and chubby 1-year-olds, 6-year-olds are grown up. As in infancy, the body and brain develop according to powerful epigenetic forces, biologically driven as well as socially guided, experience-expectant and experience-dependent (as explained in Chapter 5).

Growth Patterns Just comparing a toddling 1-year-old and a cartwheeling 6-year-old makes some differences obvious. During the play years, children become slimmer as the lower body lengthens and baby fat turns to muscle. In fact, the body mass index (or BMI, the ratio of weight to height) is lower at age 5 than at any other age in the entire life span (Guillaume & Lissau, 2002). Gone are the protruding belly, round face, short limbs, and large head that characterize the toddler. The center of gravity moves from the breastbone to the belly button, enabling cartwheels and many other motor skills.

Increases in height and weight accompany these changes in proportions. Each year from age 2 through 6, well-nourished children add almost 3 inches (about 7 centimeters) and gain about 41⁄2 pounds (2 kilograms). By age 6, the average child in a developed nation weighs about 46 pounds (21 kilograms) and is 46 inches (117 centimeters) tall. (As my nephew David said at that point, “In numbers I am square now.”)

8

207

CHAPTER OUTLINE

� Body Changes

Growth Patterns Eating Habits

� Brain Development

Speed of Thought Connecting the Brain’s Hemispheres Planning and Analyzing Emotions and the Brain Motor Skills

� Injuries and Abuse

Avoidable Injury IN PERSON: “My Baby Swallowed Poison” Child Maltreatment A CASE TO STUDY: A Series of

Suspicious Events

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A typical 6-year-old:

■ Is at least 31⁄2 feet tall (more than 100 centimeters) ■ Weighs between 40 and 50 pounds (between 18 and 22 kilograms) ■ Looks lean, not chubby (ages 5–6 are lowest in body fat) ■ Has adult-like body proportions (legs constitute about half the total height)

When many ethnic groups live together in the same developed nation, children of African descent tend to be tallest, followed by those of European descent, then Asians, and then Latinos. However, height differences within groups are greater than the average differences between groups. Body size is especially variable among children of African descent, because Africans are more genetically diverse than people from other continents (Goel et al., 2004).

Over the centuries, low-income families encouraged their children to eat, so that they would have a reserve of fat to protect them in times of famine. Now the same pattern has become destructive. In Brazil, for example, undernutrition caused two-thirds of all nutrition problems in 1975. By l997, overnutrition was the most common problem (Monteiro et al., 2004).

A detailed study of 2- to 4-year-olds in low-income families in New York City found many overweight children, with the proportion increasing as income fell (Nelson et al., 2004). Further, more 4-year-olds than 2-year-olds were overweight (27 percent compared with 14 percent), which suggests that eating habits, not

genes, were the cause. Overweight children were more likely to be of Hispanic (27 percent) or Asian (22 percent) descent than of African (14 percent) or European background (11 percent).

Such problems are not limited to New York City. Worldwide, an epidemic of adult heart disease and diabetes is spreading, and the major cause is the overfeeding of children (Gluckman & Hanson, 2006). It has been predicted that by 2020 more than 228 million adults worldwide will have diabetes (more in India than in any other nation) as a result of un- healthy eating habits acquired in childhood.

Eating Habits Compared with infants, young children—especially modern children, who play outdoors less than their

parents or grandparents did—need far fewer calories per pound of body weight. Consequently, appetite decreases between ages 2 and 6. Instead of appreciating this natural development, many parents fret, threaten, and cajole their children into eating more than they should (“Eat all your dinner, and you can have ice cream”).

Nutritional Deficiencies Although most children in developed nations consume enough calories, they do not always obtain adequate iron, zinc, and calcium. For example, consumption of calcium is lower than it was 20 years ago because children today drink less milk and more soda (Jahns et al., 2001). Another problem is sugar. Many cultures en- courage children to eat sweets, in birthday cake, holiday candy, desserts, and other treats. Yet sugar causes tooth decay, the most common disease of young children in developed nations (Lewit & Kerrebrock, 1998).

208 CHAPTER 8 ■ The Play Years: Biosocial Development

No Spilled Milk This girl is demonstrating her mastery of the motor skills involved in pouring milk, to the evident admiration of her friend. The next skill will be drinking it—not a foregone conclusion, given the lactose intol- erance of some children and the small ap- petites and notorious pickiness of children this age.

Observation Quiz (see answer, page 211): What three things can you see that indicate that this attempt at pouring will probably be successful?

LA UR

A DW

IG HT

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Sweetened cereals and drinks that are advertised as containing 100 percent of a day’s vitamin requirements are a poor substitute for a balanced diet for many rea- sons besides their high sugar content. One is that some essential nutrients have probably not yet been identified, much less listed on food labels. Another is that fresh fruits and vegetables provide more than vitamins; they also provide other diet essentials, such as fiber and fat.

Just Right Many young children are quite compulsive about daily routines, including meals. They insist on eating only certain foods, prepared and placed in a particular way. This rigidity, known as the “just right” or “just so” phenomenon, would be patholog- ical in adults but is normal and widespread among young children. For example:

Whereas parents may insist that the child eat his vegetables at dinner, the child may insist that the potatoes be placed only in a certain part of the plate and must not touch any other food; should the potatoes land outside of this area, the child may seem to experience a sense of near-contamination, setting off a tirade of fussiness for which many 2- and 3-year-olds are notorious.

[Evans et al., 1997]

Most young children’s food preferences and rituals are far from ideal. (One 3-year-old I know wanted to eat only cream cheese sandwiches on white bread; one 4-year-old, only fast-food chicken nuggets.) When 1,500 parents were surveyed about their 1- to 6-year-olds (Evans et al., 1997), over 75 percent reported that their children’s just-right phase peaked at about age 3, when the children:

■ Preferred to have things done in a particular order or in a certain way ■ Had a strong preference to wear (or not wear) certain clothes ■ Prepared for bedtime by engaging in a special activity, routine, or

ritual ■ Had strong preferences for certain foods

By age 6, this rigidity fades somewhat (see Figure 8.1). Another team of experts puts it this way: “Most, if not all, children exhibit normal age-dependent obsessive compulsive behaviors [which are] usually gone by middle childhood” (March et al., 2004, p. 216).

The best advice for parents is probably to be patient until the just- right obsession fades away. Insistence on a particular routine, a pre- ferred pair of shoes, or a favorite cup can usually be accommodated until the child gets a little older.

Overeating is another story. Almost no young child anywhere in the world, except in times of famine or war, is underfed during these years. Ideally, children would have only healthy foods to eat, a strategy that would protect their health lifelong (Gluckman & Hanson, 2006). Instead, at least in the United States, most children have several unhealthy snacks each day (Jahns et al., 2001).

SUMMING UP

During the play years, children grow steadily taller and proportionately thinner, with vari- ations depending on genes, gender, nutrition, income, and other factors. Overweight is more common than underweight. One reason is that adults encourage overeating. Another is that young children usually have small appetites and picky habits but are rewarded with foods that are high in calories yet low in nutrition.

■

Especially for Parents of Fussy Eaters You prepare a variety of vegetables and fruits, but your 4-year-old wants only French fries and cake. What should you do?

Body Changes 209

Score on “just right” survey items

1 2 43

Age (in years)

5

3.5

3

2.5

2

1.5

1

Source: Evans et al., 1997.

FIGURE 8.1

Young Children’s Insistence on Routine This chart shows the average scores of children (who are rated by their parents) on a survey indicating the child’s desire to have certain things—including food selection and preparation—done “just right.” Such strong preferences for rigid routines tend to fade by age 6.

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Brain Development Brains grow rapidly even before birth. By age 2, not only have brains increased in size but also a great deal of pruning of dendrites has already occurred. The 2-year- old brain weighs 75 percent of what it will weigh in adulthood. (The major struc- tures of the brain are diagrammed in Appendix A, p. A-30.)

Since most of the brain is already present and functioning, what remains to develop after age 2? The most important parts! Those functions of the brain that make us most human are the ones that develop after infancy, enabling quicker, more coordinated, and more reflective thought (Kagan & Herschkowitz, 2005). Brain growth after infancy is a crucial difference between humans and other animals.

Speed of Thought After infancy, continued proliferation of the communication pathways (dendrites and axons) results in some brain growth. However, most of the increase in brain weight (to 90 percent of adult weight by age 5) occurs because of myelination (Sampaio & Truwit, 2001). Myelin is a fatty coating on the axons that speeds signals between neurons, like insulation wrapped around electric wires to aid conduction.

The effects of myelination are most noticeable in early childhood (Nelson et al., 2006). Greater speed becomes pivotal when several thoughts must occur in rapid succession. By age 6 most children can listen and then answer, catch a ball and then throw it, write the alphabet in sequence, and so on.

Parents must still be patient when listening to young children talk, when help- ing them get dressed, or when watching them try to write their names. All these tasks are completed more slowly by 6-year-olds than by 16-year-olds. However, thanks to myelination, preschoolers are at least quicker than toddlers, who may take so long that they forget what they were doing before they finish.

Connecting the Brain’s Hemispheres One part of the brain that grows and myelinates rapidly during the play years is the corpus callosum, a band of nerve fibers that connect the left and right sides of the brain (see Figure 8.2). Growth of the corpus callosum makes communication between the two brain hemispheres more efficient, allowing children to coordinate the two sides of the brain or body. Failure of the corpus callosum to develop normally may result in serious disorders, including autism (Diwadkar & Keshavan, 2006).

To understand the significance of coordination of the two brain hemispheres, you need to realize that the two sides of the body and brain are not identical. Each side specializes, so each is dominant for certain functions—a process called lateralization. Lateralization, or “sidedness,” is apparent not only in right- or left-handedness but also in the feet, eyes, ears, and the brain itself. Such special- ization is epigenetic, prompted by genes, prenatal hormones, and early experiences.

The Left-Handed Child Infants and toddlers usually prefer one hand over the other for grabbing a spoon, a rattle, and so on. For centuries, parents who saw a preference for the left hand forced their children to be right-handed. Indeed, since most people are right- handed, the common assumption was that right-handedness was best. This bias is still evident in language. In English, a “left-handed compliment” is insincere, and no one wants to be “left back” or “out in left field.” In Latin, dexter (as in dexterity) means “right” and sinister means “left” (and also “evil”). Gauche, which in English means “socially awkward,” is the French word for “left.”

myelination The process by which axons become coated with myelin, a fatty sub- stance that speeds the transmission of nerve impulses from neuron to neuron.

corpus callosum A long band of nerve fibers that connect the left and right hemispheres of the brain.

lateralization Literally, sidedness. The spe- cialization in certain functions by each side of the brain, with one side dominant for each activity. The left side of the brain con- trols the right side of the body, and vice versa.

210 CHAPTER 8 ■ The Play Years: Biosocial Development

Especially for Early-Childhood Teachers You know you should be patient, but you feel your frustration rising when your young charges dawdle on the walk to the playground a block away. What should you do?

➤Response for Parents of Fussy Eaters (from page 209): The nutritionally wise answer would be to offer only fruits, vegetables, and other nourishing, low-fat foods, counting on the child’s eventual hunger to drive him or her to eat them. However, centuries of cultural custom make it almost impossible for parents to be wise in such cases. Perhaps the best you can do is to discuss the dilemma with a nutritionist or pediatrician, who can advise you about what to do for your particular child.

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Customs, including taboos, also favor right-handed people. For example, in many Asian and African nations, only the left hand is used for wiping after defecation; it is a major insult to give someone anything with that “dirty” hand.

Developmentalists advise against trying to switch a child’s handedness, not only because this causes needless parent–child conflict but also because it might inter- fere with the natural and necessary process of lateralization. Left-handed adults tend to have thicker corpus callosa than others, which may enable better coordi- nation of both sides of the body (Cherbuin & Brinkman, 2006). A disproportion- ate number of artists, musicians, and sports stars are left-handed.

The Whole Brain Through studies of people with brain damage as well as through brain imaging, neurologists have determined how the brain’s hemispheres specialize: The left half controls the right side of the body and contains the areas dedicated to logical reasoning, detailed analysis, and the basics of language; the right half controls the left side of the body and contains the areas dedicated to generalized emotional and creative impulses, including appreciation of most music, art, and poetry. Thus, the

Brain Development 211

Corpus callosum

(a)

(b)

FIGURE 8.2

Connections Two views of the corpus callosum, a band of nerve fibers (axons) that convey information between the two hemispheres of the brain. When developed, this “connector” allows the person to coordinate functions that are performed mainly by one hemisphere or the other. (a) A view from between the hemispheres, looking toward the right side of the brain. (b) A view from above, with the gray matter removed in order to expose the corpus callosum.

Especially for Left-Handed Adults If you have a left-handed child (as you very well might, since handedness is partly genetic), at what age would you try to switch him or her?

➤Answer to Observation Quiz (from page 208): The cup, the pitcher, and the person. The cup has an unusually wide opening; the pitcher is small and has a sturdy handle; and the girl is using both hands and giving her full concentration to the task.

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left side notices details and the right side grasps the big picture—a distinction that should provide a clue in interpreting Figure 8.3.

No one (except severely brain-damaged people) is exclusively left- brained or right-brained. Every cognitive skill requires both sides of the brain, just as gross motor skills require both sides of the body (Hugdahl & Davidson, 2002). Because older children have more myelinated fibers in the corpus callosum to speed signals between the two hemispheres, better thinking and less clumsy actions are possible for them.

Planning and Analyzing You learned in Chapter 5 that the prefrontal cortex (sometimes called the frontal cortex or frontal lobe) is an area in the very front part of the brain’s outer layer (the cortex), under the forehead. It “underlies

higher-order cognition, including planning and complex forms of goal-directed behavior” (Luciana, 2003, p. 163). The prefrontal cortex is crucial for humans; it is said to be the executive of the brain because all the other areas of the cortex are ruled by prefrontal decisions. For example, a person might feel anxious on meeting someone new, whose friendship may be valuable in the future. The prefrontal cortex can calculate and plan, not letting the anxious feelings prevent the acquaintance.

Maturation of the Prefrontal Cortex The frontal lobe “shows the most prolonged period of postnatal development of any region of the human brain” (Johnson, 2005, p. 210), with dendrite density and myelination increasing throughout childhood and adolescence (Nelson et al., 2006). Several notable benefits of maturation of the prefrontal cortex occur from ages 2 to 6:

■ Sleep becomes more regular. ■ Emotions become more nuanced and responsive to specific stimuli. ■ Temper tantrums subside. ■ Uncontrollable laughter or tears become less common.

In one series of experiments, 3-year-olds consistently made a stunning mistake (Zelazo et al., 2003). The children were given a set of cards with clear outlines of trucks or flowers, some red and some blue. They were asked to “play the shape game,” putting trucks in one pile and flowers in another. Three-year-olds can do this correctly, as can some 2-year-olds and almost all older children.

Then the children were asked to “play the color game,” sorting the cards by color. Most of them failed at this task, sorting by shape instead. This study has been replicated in many nations, and 3-year- olds usually get stuck on their initial sorting pattern (Diamond & Kirkham, 2005). Most older children, even 4-year-olds, make the switch.

When this result was first obtained, experimenters wondered whether the children didn’t know their colors, so the scientists switched the order, first playing “the color game.” Most 3-year-olds did that correctly. Then, when they were asked to play “the shape game,” they still sorted by color. Even with a new set of cards, such as yellow or green rabbits or boats, they still tend to sort by the criterion (either color or shape) that was used in their first trial.

Researchers are looking into many possible explanations for this surprising result (Müller et al., 2006; Yerys & Munakata, 2006). All

212 CHAPTER 8 ■ The Play Years: Biosocial Development

FIGURE 8.3

Copy What You See Brain-damaged adults were asked to copy the figure at the left in each row. One person drew the middle set, another the set at the right.

Observation Quiz (see answer, page 214): Which set was drawn by someone with left- side damage and which set by someone with right-side damage?

No Writer’s Block The context is designed to help this South African second-grader concentrate on her schoolwork. Large, one- person desks, uniforms, notebooks, and sharp pencils are manageable for the brains and skills of elementary school children, but not yet for preschoolers.

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agree, however, that something in the executive function of the brain must mature before children are able to switch from one way of sorting objects to another.

An everyday example is the game Simon Says, in which children are supposed to follow the leader only when his or her orders are preceded by the words “Simon says.” Thus when leaders touch their noses and say, “Simon says touch your nose,” children are supposed to touch their noses; but when leaders touch their noses and merely say, “Touch your nose,” no one is supposed to follow the example. Young children quickly lose at this game because they impulsively do what they see and are told to do. Older children are better at it because they can think before acting.

Maturation of the prefrontal cortex is also discussed in Chapters 5, 11, and 14.

Attention A major function of the prefrontal cortex is to focus attention and thus to curb impul- siveness. A 3-year-old jumps from task to task and cannot be still, even in church or any other place that requires quiet. Similarly, younger children may want to play with a toy that another child has but lose interest by the time that toy becomes available.

The opposite of the impatient child is the child who plays with one toy for hours. Perseveration is the name for the tendency to persevere in, or stick to, one thought or action. Perseveration is evident in the card-sorting study and in young children’s tendency to repeat one phrase or question again and again or to throw a tantrum when their favorite TV show is interrupted. That tantrum itself may perseverate: The child’s crying may become uncontrollable and unstoppable, as if the child is stuck in that emotion.

Impulsiveness and perseveration are opposite behaviors with the same under- lying cause: immaturity of the prefrontal cortex. Over the play years, brain matura- tion (innate) and emotional regulation (learned) decrease both impulsiveness and perseveration. Children gradually become able to pay attention when necessary (de Haan & Johnson, 2003).

Emotions and the Brain Now that we have looked at the brain structures involved in planning and analyzing, we turn to the limbic system, an area of the brain that is crucial in the expression and regulation of emotions. Both expression and regulation advance during the play years (more about that in Chapter 10). Three major parts of the limbic system are the amygdala, the hippocampus, and the hypothalamus.

The amygdala, a tiny structure deep in the brain (named after an almond, be- cause it is about that shape and size), registers emotions, both positive and negative, especially fear (Nelson et al., 2006). Increased activity of the amygdala is one reason some young children have terrifying nightmares or sudden terrors.

Fear can overwhelm the prefrontal cortex and disrupt a child’s ability to reason. If a child is scared of, say, a lion in the closet, an adult should open the closet door and tell the lion to go home, not laugh or insist that the fear is nonsense.

The amygdala responds to facial expressions (Vasa & Pine, 2004). This is part of social referencing, explained in Chapter 7. If a child sees a parent look terrified when a strange dog approaches, the child may also feel extreme fear, and if this recurs often enough, the child’s amygdala may become hypersensitive. If instead the parent conveys pleasure or curiosity about the dog, the child will probably overcome initial feelings of fear because of another structure in the brain’s limbic system, the hippocampus.

The hippocampus is located right next to the amygdala. It is a central proces- sor of memory, especially memory of locations. The hippocampus responds to the

perseveration The tendency to persevere in, or stick to, one thought or action for a long time.

amygdala A tiny brain structure that registers emotions, particularly fear and anxiety.

Brain Development 213

➤Response for Early-Childhood Teachers (from page 210): One solution is to remind yourself that the children’s brains are not yet myelinated enough to enable them to quickly walk, talk, or even button their jackets. Maturation has a major effect, as you will observe if you can schedule excursions in September and again in November. Progress, while still slow, will be a few seconds faster in November than it was in September.

➤Response for Left-handed Adults (from page 211): Preferably never! Most left-handed adults are quite proud of their distinctiveness. Developmentalists now recommend that natural dominance prevail. However, if you still want your child to switch, early childhood is too late, as brain lateraliza- tion has begun. In the first weeks of life, you might encourage right-handedness—but don’t insist.

hippocampus A brain structure that is a central processor of memory, especially the memory of locations.

Especially for Brain Experts Why do most neurologists think the limbic system is an oversimplification?

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anxieties of the amygdala with memory; it makes the child remember, for instance, that Mother petted a dog at a neighbor’s house.

Memories of location are fragile in early childhood because the hippocampus is still developing. Indeed, every type of memory has its own timetable (Nelson & Webb, 2003); for example, memory for context is less advanced than memory for content, and source memory (of when, where, and how a certain fact was learned) is hazy (Cycowicz et al., 2003). A preschool child might claim “No one told me that. I always knew it” or might remember that something happened but mis- remember who was involved.

The amygdala and the hippocampus are sometimes helpful, sometimes not, de- pending on how useful fear and memory are. Some children, because their amyg- dala and hippocampus are not well developed, might be fearless when they should remember past events and be cautious. When the amygdala is surgically removed from animals, they are fearless in situations that should scare them; cats will stroll nonchalantly along when monkeys are nearby, for instance—something no normal cat would do (Kolb & Whishaw, 2003).

A third part of the limbic system, the hypothalamus, responds to signals from the amygdala (arousing) and the hippocampus (usually dampening) to produce hormones that activate other parts of the brain and body (see Figure 8.4). Ideally, this occurs in moderation. If excessive stress hormones flood the brain, part of the hippocampus may be destroyed. Permanent deficits in learning and memory may result (Davis et al., 2003).

hypothalamus A brain area that responds to the amygdala and the hippocampus to pro- duce hormones that activate other parts of the brain and body.

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The HPA (Hypothalamus-Pituitary-Adrenal Cortex) Axis

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Positive feedback loop Negative feedback loop

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Source: Adapted from Davis et al., 2003, p. 183.

Hippocampus Amygdala

FIGURE 8.4

A Hormonal Feedback Loop This diagram simplifies a hormonal linkage, the HPA axis, involving the limbic system. Both the hippocampus and the amygdala stimulate the hypothalamus to produce CRH (corticotropin-releasing hormone), which in turn signals the pituitary gland to produce ACTH (adrenocorticotropic hormone). ACTH then triggers the pro- duction of CORT (glucocorticoids) by the adrenal cortex (the outer layers of the adrenal glands, atop the kidneys). The initial reaction to something frightening may either build or disappear, depending on other factors, including memories, and on how the various parts of the brain interpret that first alert from the amygdala. (Some other components of this mechanism have been omitted for the sake of clarity.)

➤Answer to Observation Quiz (from page 212): The middle set, with its careful details, reflects damage to the right half of the brain, where overall impressions are formed. The person with left-brain damage produced the drawings that were just an M or a �, without the details of the tiny z’s and rectangles. With a whole functioning brain, people can see both “the forest and the trees.”

➤Response for Brain Experts (from page 213): The more we discover about the brain, the more complex we realize it is. Each part has specific functions and is connected to every other part.

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Stressful experiences—meeting new friends, entering school, visiting a strange place—probably foster growth if the child has someone or something to moderate the stress. In an experiment, brain scans and tests of hormone levels measured stress in 4- to 6-year-olds after a fire alarm. Two weeks later, they were questioned about the event. Compared with less reactive children, those with higher stress reactions to the alarm remembered more with a friendly interviewer but less with a stern interviewer (Quas et al., 2004).

Other research also finds that preschoolers remember traumatic experiences better if the interviewer is a warm and attentive listener (Bruck et al., 2006). But stress should not be relentless, without long recovery, because developing brains are fragile; “prolonged physiological responses to stress and challenge put chil- dren at risk for a variety of problems in childhood, including physical and mental disorders, poor emotional regulation, and cognitive impairments” (Quas et al., 2004, p. 379).

Prolonged stress, with emotional and cognitive impairment, seemed to occur for the thousands of Romanian children in orphanages (see Chapter 5). When they saw pictures of happy, sad, frightened, and angry faces, their limbic systems were less reactive than were those of Romanian children living with their parents. The brains of the orphans were less lateralized, suggesting less specialized, less efficient thinking (Parker & Nelson, 2005).

Motor Skills Maturation of the prefrontal cortex improves impulse control, while myelination of the corpus callosum and lateralization of the brain permits better coordination. No wonder children move with greater speed and grace as they age from 2 to 6, becoming better able to direct and refine their actions. (Table 8.1 lists approxi- mate ages for the acquisition of various motor skills.)

Brain Development 215

TABLE 8.1

AT ABOUT THIS TIME: Motor Skills at Ages 2–6*

Approx. Skill or Approx. Skill or Age Achievement Age Achievement

2 years Run for pleasure, without falling (but bumping into things) Climb chairs, tables, beds, out of cribs Walk up stairs Feed self with spoon Draw lines, spirals

3 years Kick and throw a ball Jump with both feet off the floor Pedal a tricycle Copy simple shapes (e.g., circle, rectangle) Walk downstairs Climb ladders

4 years Catch a ball (not too small or thrown too fast) Use scissors to cut Hop on either foot Feed self with fork Dress self (no tiny buttons, no ties) Copy most letters Pour juice without spilling Brush teeth

5 years Skip and gallop in rhythm Clap, bang, sing in rhythm Copy difficult shapes and letters (e.g., diamond shape,

letter S) Climb trees, jump over things Use knife to cut Tie a bow Throw a ball Wash face, comb hair

6 years Draw and write with one hand Write simple words Scan a page of print, moving the eyes systematically in

the appropriate direction Ride a bicycle Do a cartwheel Tie shoes Catch a ball

*Context is crucial. (Many 6-year-olds cannot tie shoelaces because they have no shoes with laces.)

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The Joy of Climbing Would you delight in climbing on an unsteady rope swing, like this 6-year-old in Japan (and almost all his contemporaries worldwide)? Each age has special sources of pleasure.

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According to a study of middle-class and working-class children in Brazil, Kenya, and the United States (Tudge et al., 2006; see Research Design), young children spend the majority of their waking time in play, more than they spend in three other important activities (doing chores, learning lessons, or having conver- sations with adults) combined (see Figure 8.5). Mastery of gross and fine motor skills is one result of the extensive active play of young children.

Gross Motor Skills Gross motor skills—which, as defined in Chapter 5, involve large body move- ments—improve dramatically. When you watch children play, you can see clumsy 2-year-olds who fall down and sometimes bump into each other, but you can also see 5-year-olds who are both skilled and graceful.

Most North American 5-year-olds can ride a tricycle; climb a ladder; pump a swing; and throw, catch, and kick a ball. Some can skate, ski, dive, and ride a bicycle—activities that demand balance as well as coordination. In some nations, 5-year-olds swim in oceans or climb cliffs. A combination of brain maturation, mo- tivation, and guided practice makes each of these skills possible.

Adults need to make sure children have safe space, time, and playmates; skills will follow. According to sociocultural theory, children learn best from peers who demonstrate whatever skills—from catching a ball to climbing a tree—the child is ready to try.

216 CHAPTER 8 ■ The Play Years: Biosocial Development

Source: Tudge et al., 2006.

65 60 55 50 45 40 35 30 25 20 15 10 5

Middle- class

European Americans

African Americans

Brazilians Kenyans

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Middle- class

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Middle- class

Working- class

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Time Spent by 3-Year-Olds in Various Activities Play

Activity Categories:

Lessons Work Conversation Other

FIGURE 8.5

Mostly Playing When researchers studied 3-year-olds in the United States, Brazil, and Kenya, they found that, on average, the children spent more than half their time playing. Note the low percentages of both middle- and working-class Brazilian children in the Lessons category, which included all intentional efforts to teach children something. There is a cultural explanation: Unlike parents in Kenya and the United States, most Brazilian parents believe that children this age should not be in organized day care.

Research Design Scientists: Jonathan Tudge and others (e.g., researchers in Brazil and Kenya).

Publication: Child Development (2006).

Participants: About 20 3-year-olds from each of four ethnic groups: European American and African American in Greensboro, North Carolina; Luo in Kisumu, Kenya; and European descent in Porto Alegre, Brazil. On the basis of parents’ education and occupation, half the children in each group were from middle-class families and half were from working-class families.

Design: Children were observed for 20 hours each in their usual daytime activities.The child wore a wireless microphone; every 6 minutes, the observer recorded what the child was doing. Later the time was allocated among five categories: Lessons (deliber- ate attempts to impart information), Work (household tasks), Play (activities for enjoyment), Conversation (sustained talk with adults about things not the current focus of activity), and Other (eating, bathing, sleeping).

Major conclusion: All eight groups spent much more time playing than doing anything else. Much larger differ- ences were found in time spent in lessons, work, and conversation.

Comment: Many features of good research are evident in this study.

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Fine Motor Skills Fine motor skills, which involve small body movements (especially those of the hands and fingers), are harder to master. Pouring juice into a glass, cutting food with a knife and fork, and achieving anything more artful than a scribble with a pencil require muscular control, patience, and judgment that are beyond most 2-year-olds.

Many fine motor skills involve two hands and thus both sides of the brain: The fork stabs the meat while the knife cuts it; one hand steadies the paper while the other writes; tying shoes, buttoning shirts, pulling on socks, and zipping zippers require both hands. An immature corpus callosum and prefrontal cortex may be the underlying reason that shoelaces get knotted, paper gets ripped, and zippers get stuck. Short, stubby fingers and confusion about handedness add to the problem.

Artistic Expression During the play years, children are imaginative, creative, and not yet self-critical. They love to express themselves, especially if their parents applaud, display their artwork, and otherwise communicate approval. It may be that the relative immatu- rity of the prefrontal cortex allows imagination free rein, without the social anxiety of older children, who might say “I can’t draw” or “I am horrible at dancing.”

All forms of artistic expression blossom during early childhood. Children love to dance around the room, build an elaborate tower of blocks, make music by pounding in rhythm, and put bright marks on shiny paper.

Children’s artwork reflects their unique perception and cognition. For example, researchers asked young children to draw a balloon and, later, a lollipop. To adults, the drawings were indistinguishable, but the children who made the drawings were quite insistent as to which was which (Bloom, 2000) (see Figure 8.6).

Especially for Immigrant Parents You and your family eat with chopsticks at home, but you want your children to feel comfortable in Western culture. Should you change your family’s eating customs?

Brain Development 217

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Snip, Snip Cutting paper with scissors is a hard, slow task for a 3-year-old, who is just beginning to develop fine motor control. Imagine wielding blunt “safety” scissors and hoping that the paper will be sliced exactly where you want it to be.

FIGURE 8.6

Which Is Which? The child who made these drawings insisted that the one at top left was a lollipop and the one at top right was a balloon (not vice versa) and that the drawing at bottom left was the experimenter and the one at bottom right was the child (not vice versa).

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In every artistic domain, from dance to sculpture, maturation of brain and body is gradual and comes with practice. For example, when drawing the human figure, 2- to 3-year-olds usually draw a “tadpole”—a circle for a head with eyes and sometimes a smiling mouth, and then a line or two beneath to indicate the rest of the body. Gradually, children’s drawings of people evolve from tadpoles into more human forms.

Tadpoles are “strikingly characteristic” of children’s art (Cox, 1993); they are drawn universally, in all cultures. Similarly, children worldwide seek places to climb—on rocky hillsides, playground structures, and the dining room table— imagining as they play. They like challenges that they can meet.

SUMMING UP

The brain continues to mature during early childhood, with myelination in several crucial areas. One is the corpus callosum, which connects the left and right sides of the brain and therefore the right and left sides of the body. Increased myelination speeds up actions and reactions. The prefrontal cortex enables impulse control, allowing children to think before they act as well as to stop one action in order to begin another. As impul- siveness and perseveration decrease, children become better able to learn. Several key areas of the brain—including the amygdala, the hypothalamus, and the hippocampus— make up the limbic system, which also matures from ages 2 to 6. The limbic system aids emotional expression and control. Maturation of the brain leads to better control of the body and hence to development of motor skills.

■

Injuries and Abuse Throughout this text, we have assumed that parents want to foster their children’s development and protect them from danger. That is true in the vast majority of families. Yet more children die of violence—either accidental or deliberate—than from any other cause.

In the United States, where accurate death records are kept, out of every 100,000 1- to 4-year-olds, 10.9 died accidentally, 2.5 died of cancer (the leading

218 CHAPTER 8 ■ The Play Years: Biosocial Development

No Ears? (a) Jalen was careful to include all seven of her family members who were pres- ent when she drew her picture. She tried to be realistic—by, for example, portraying her cousin, who was slumped on the couch, in a horizontal position. (b) Elizabeth takes pride in a more difficult task, drawing her family from memory. All have belly buttons and big smiles that reach their foreheads, but they have no arms or hair. (c) By age 6, this Virginia girl draws just one family member in detail— nostrils and mustache included.

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fatal disease at this age), and 2.4 were murdered in 2003 (U.S. Bureau of the Census, 2006).

Young children are more vulnerable to injuries and abuse than are slightly older ones, partly because they are impulsive yet dependent on others, as we have just seen. Much of the harm to children can be prevented, and that is our primary reason for discussing this topic in detail.

Avoidable Injury Worldwide, injuries cause millions of premature deaths among young adults as well as children: Not until age 40 does any disease overtake accidents as a cause of mortality. Among children, the 1- to 4-year-olds are most vulnerable to accidental death and injury (MMWR, September 3, 2004).

Age-related trends are apparent in the particular kinds of injuries. Teenagers and young adults are most often killed as passengers or drivers in motor-vehicle accidents. Falls are more often fatal for the very young (under 24 months) and very old (over 80 years) than for preschoolers. For preschoolers, fatal accidents are more likely to involve poison, fire, choking, or drowning.

Why do small children have so many accidents? Immaturity of the prefrontal cortex makes young children impulsive, so they plunge into dangerous places and activities (Zeedyk et al., 2002). Unlike infants, their motor skills allow them to run, leap, scramble, and grab in a flash. Their curiosity is boundless; their impulses are uninhibited.

Injury Control As one team of experts notes, “Injuries are not unpredictable, unavoidable events. To a large extent, society chooses the injury rates it has” (Christoffel & Gallagher, 1999, p. 10). How could a society choose unnecessarily high rates of injury, pain, and lifelong damage? Injury prevention is no accident; it is a choice made by par- ents, by legislators, and by society as a whole.

To understand this, consider the implications of the terminology. The word acci- dent implies that an injury is a random, unpredictable event. If anyone is at fault, a careless parent or an accident-prone child might be blamed. This is called the “accident paradigm”; it implies that “injuries will occur despite our best efforts,” and it allows the general public to feel blameless (Benjamin, 2004, p. 521).

In response, experts now prefer the term injury control (or harm reduction) instead of accident prevention. Injury control implies that harm can be minimized if appropriate controls are in place. Minor mishaps are bound to occur, but the damage is reduced if a child falls on a safety surface instead of concrete, if a car seat protects the body in a crash, if a bicycle helmet cracks instead of a skull, if the swallowed pills come from a tiny bottle.

Only half as many 1- to 5-year-olds in the United States were fatally injured in 2005 as in 1985, thanks to laws that govern poisons, fires, and cars. But now the leading cause of unintentional death for children aged 1 to 5 is drowning in a swimming pool (Brenner et al., 2001). To prevent most such deaths, govern- ment officials need only require that any body of water near a home have a high fence around it.

A pool-fencing ordinance in southern California allowed one side of the enclo- sure to be the wall of a house, with a door that could be locked. This seemed rea- sonable to homeowners but not to pediatricians. The law protected trespassing children but not the family’s own children, who knew how to open those doors. After the law was passed, California child drownings did not decline (Morgenstern et al., 2000).

injury control/harm reduction Practices that are aimed at anticipating, controlling, and preventing dangerous activities; these practices reflect the beliefs that accidents are not random and that injuries can be made less harmful if proper controls are in place.

Injuries and Abuse 219

➤Response for Immigrant Parents (from page 217): Children develop the motor skills that they see and practice. They will soon learn to use forks, spoons, and knives. Do not abandon chopsticks completely, because young children can learn several ways of doing things, and the ability to eat with chopsticks is a social asset.

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Three Levels of Prevention Injury prevention should begin long before any particular child, parent, or politician does something foolish or careless. Of the three levels of prevention described below, the one that is least noticed by individuals but most effective overall is the first level (Cohen et al., 2007).

■ In primary prevention, the overall situation is structured to make injuries less likely. Primary prevention fosters conditions that reduce everyone’s chance of injury, no matter what their circumstances.

■ Secondary prevention is more specific, averting harm to individuals in high-risk situations.

■ Tertiary prevention begins after an injury, limiting the damage it causes. Tertiary prevention saves lives and reduces the number and severity of per- manent disabilities.

To illustrate, the rate of pedestrian deaths in motor-vehicle accidents has steadily decreased in the past 20 years because of all three levels of prevention. How does each level contribute to this welcome decline?

Primary prevention includes sidewalks, speed bumps, pedestrian overpasses, brighter streetlights, and single-lane traffic circles (Retting et al., 2003; Tester et al., 2004). Cars have been redesigned (e.g., better headlights and brakes) and drivers’ skills improved (e.g., as a result of more frequent vision tests and stronger drunk-driving penalties).

Secondary prevention reduces the dangers in high-risk situations. For children this means requiring flashing lights on stopped school buses, employing school- crossing guards, refusing alcohol to teenagers, and insisting that young children walk with adults, who are more careful crossing streets. For the aged, this means longer red lights and well-marked crosswalks.

The distinction between primary prevention and secondary prevention is not clear-cut. In general, secondary prevention is more targeted, focusing on specific risk groups (e.g., young children) and proven dangers (e.g., walking to school) rather than on the overall culture, politics, or environment.

Finally, tertiary prevention reduces damage after accidents. Laws against hit- and-run driving, improved emergency-room procedures (e.g., faster action to re-

Especially for Urban Planners Describe a neighborhood park that would benefit 2- to 5-year-olds.

primary prevention Actions that change overall background conditions to prevent some unwanted event or circumstance, such as injury, disease, or abuse.

secondary prevention Actions that avert harm in a high-risk situation, such as stop- ping a car before it hits a pedestrian.

tertiary prevention Actions, such as imme- diate and effective medical treatment, that are taken after an adverse event such as illness or injury occurs, and are aimed at reducing the harm or preventing disability.

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And If He Falls . . . None of these children is injured, so no tertiary prevention is needed. Photos (b) and (c) both illustrate secondary prevention. In photo (a), the metal climbing equipment with large gaps and peeling paint is hazardous. Primary prevention suggests that this “attractive nuisance” be dismantled.

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duce brain swelling), and more effective rehabilitation are examples of tertiary prevention. Speedy and well-trained ambulance teams may be the most important: If an injured person arrives at a hospital within the “golden hour” after an acci- dent, the chances of recovery are much better (Christoffel & Gallagher, 1999). In many European countries, tertiary prevention has involved redesigning the fronts of cars so that they are less destructive to pedestrians when accidents do occur (Retting et al., 2003).

Many measures at all three levels have been instituted, to good effect. In the United States, pedestrian deaths decreased from 8,842 in 1990 to 4,600 in 2004 (U.S. Bureau of the Census, 2006). Similar trends are found in almost every nation, for almost every fatal injury.

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A Safe Leap What makes this jump safe as well as fun are the high fences on all sides of the pool, the adequate depth of the water, and the presence of at least one adult (taking the picture).

“My Baby Swallowed Poison”

The first strategy that most people think of for preventing in- jury to young children is parental education. However, public health research finds that laws that apply to everyone are more effective than education, especially if parents are not ready to learn and change or are overwhelmed by the daily demands of child care.

For example, the best time to convince parents to use an infant seat in their car (which has saved thousands of young lives) is before they bring their newborn home from the hospi- tal. Voluntary use of car seats is much less common than man- dated use.

As one expert explains: “Too often, we design our physical environment for smart people who are highly motivated” (Baker, 2000). In real life, everyone has moments of foolish indifference. At those moments, automatic safety measures save lives.

I know this firsthand. My daughter Bethany, at age 2, climbed onto the kitchen counter to find, open, and swallow most of a bottle of baby aspirin. Where was I? A few feet away, nursing our second child and watching television. I did not notice what Bethany was doing until I checked on her during a commercial.

What prevented serious injury? Laws limiting the number of baby aspirin per container (primary prevention), my pediatrician telling me on my first well-baby checkup to buy syrup of ipecac (secondary prevention), and my phone call to Poison Control (tertiary prevention). I told the stranger who answered the phone, “My baby swallowed poison.” He calmly asked me ques- tions and then told me to make Bethany swallow ipecac so that she’d throw up the aspirin. I did and she did. I still blame myself, but I am grateful for all three levels of prevention that protected my child.

in person

Especially for Socially Aware Students In the “In Person” feature below, how did Kathleen Berger’s SES protect Bethany from serious harm?

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child maltreatment Intentional harm to or avoidable endangerment of anyone under 18 years of age.

child abuse Deliberate action that is harmful to a child’s physical, emotional, or sexual well-being.

child neglect Failure to meet a child’s basic physical, educational, or emotional needs.

Child Maltreatment The next time you read news headlines about some horribly neglected or abused child, think of these words from a leading researcher in child maltreatment:

Make no mistake—those who abuse children are fully responsible for their actions. However, creating an information system that perpetuates the message that offenders are the only ones to blame may be misleading. . . . We all contribute to the conditions that allow perpetrators to succeed.

[Daro, 2002, p. 1133]

We all contribute in the sense that the causes of child maltreat- ment are multifaceted, involving not only the parents but also the maltreated children, the community, and the culture. For example, infants are most at risk of being maltreated if they themselves are difficult (fragile, needing frequent feeding, crying often) and if their

mothers are depressed and do not feel in control of their lives or their infants and if the family is under stress because of poverty (Bugental & Happaney, 2004).

Maltreatment Noticed and Defined Noticing is the first step. Until about 1960, people thought child maltreatment was rare and usually consisted of a sudden attack by a disturbed stranger. Today, thanks to a pioneering study based on careful observation in one Boston hospital (Kempe & Kempe, 1978), we know better: Maltreatment is neither rare nor sud- den and the perpetrators are often the child’s own parents. That makes it much worse: Ongoing maltreatment, with no safe haven, is much more damaging to children than a single brief incident, however abusive (Manly et al., 2001).

With this recognition came a broader definition: Child maltreatment now refers to all intentional harm to, or avoidable endangerment of, anyone under 18 years of age. Thus, child maltreatment includes both child abuse, which is delib- erate action that is harmful to a child’s physical, emotional, or sexual well-being, and child neglect, which is failure to appropriately meet a child’s basic physical or emotional needs.

The more that researchers study child maltreatment, the more apparent the harmful effects of neglect become (Hildyard & Wolfe, 2002). As one team wrote, “Severe neglect occurring in the early childhood years has been found to be partic- ularly detrimental to successful adaptation” (Valentino et al., 2006, p. 483). How frequently does maltreatment occur? It is impossible to say. Not all cases of mal- treatment are noticed, not all that are noticed are reported, and not all that are reported are substantiated.

Reported maltreatment occurs when the authorities have been informed about the situation. Since 1993, the number of reported cases of maltreatment in the United States has ranged from 2.7 million to 3 million a year (U.S. Department of Health and Human Services, 2006). Cases of substantiated maltreatment are those that have been investigated and verified (see Figure 8.7). The number of substantiated cases in 2004 was 872,000 (one-fourth of which victimized 2- to 5-year-olds), or about 1 maltreated child in every 70 aged 2 to 5 (U.S. Department of Health and Human Services, 2006). This 3-to-1 ratio of reported to substanti- ated cases can be attributed to three factors:

■ Each child is counted once, even if repeated maltreatment is reported. ■ Substantiation requires proof in the form of unmistakable injuries, serious mal-

nutrition, or a witness willing to testify. Such evidence is not always available. ■ A report may be false or deliberately misleading (less than 1 percent).

222 CHAPTER 8 ■ The Play Years: Biosocial Development

Nobody Watching? Madelyn Gorman Toogood looks around to make sure no one is watching before she slaps and shakes her 4-year-old daughter, Martha, who is in a car seat inside the vehicle. A security camera recorded this incident in an Indiana depart- ment store parking lot. A week later, after the videotape was repeatedly broadcast nation- wide, Toogood was recognized and arrested. The haunting question is: How much child abuse takes place that is not witnessed?

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reported maltreatment Harm or endanger- ment about which someone has notified the authorities.

substantiated maltreatment Harm or endangerment that has been reported, investigated, and verified.

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How often does maltreatment go unreported? According to a national, confi- dential survey of young adults in the United States, 1 in 4 had been physically abused (“slapped, hit, or kicked” by a parent or other adult caregiver) before sixth grade and 1 in 22 had been sexually abused (“touched or forced to touch someone else in a sexual way”) (Hussey et al., 2006; see Research Design).

One reason for these high rates may be that young adults were asked if they had ever been mistreated by someone who was caring for them, while most other sources report annual rates. The authors of this study think the rates they found are underestimates!

Warning Signs of Maltreatment Often the first sign of maltreatment is delayed development, such as slow growth, immature communication, lack of curiosity, or unusual social interactions. All these difficulties may be evident even at age 1 (Valentino et al., 2006).

During the play years, a maltreated child may seem fearful, startled by noise, defensive and quick to attack, and confused between fantasy and reality. These may be symptoms of post-traumatic stress disorder (PTSD), a disorder first identified in combat veterans, then in adults who had experienced some emotional injury or shock (in reaction to a serious accident or violent crime, for example). It now seems evident in some maltreated children (De Bellis, 2001; Yehuda, 2006).

By school age, neglected children tend to be withdrawn and self-critical; abused children tend to be aggressive; neither is resilient to stress. At every age, maltreated children are less likely to have friends (Manly et al., 2001).

Table 8.2 lists signs of maltreatment, both neglect and abuse. None of these signs are proof, but whenever any of them occurs, it signifies trouble. Many nations, including the United States, now require professionals who deal with children (teachers, nurses, social workers, doctors, police officers) to report any suspected maltreatment. Not all professionals know when to be suspicious, however. For

Injuries and Abuse 223

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1990 1991 1992 1993 1994 1995 1996

Year

1997 1998 1999 2000 2001 2002 2003 2004

Source: U.S. Department of Health and Human Services, 2006 and previous years.

Number of cases per 1,000 children

FIGURE 8.7

Rates of Substantiated Child Maltreatment, United States, 1990–2004 The number of reported and substantiated cases of maltreatment of children under age 18 in the United States is too high, but there is some good news: The rate has declined significantly from the peak in 1993.

Observation Quiz (see answer, page 225): The dot for 1999 is close to the bottom of the graph. Does that mean it is close to zero?

Research Design Scientists: Jon Hussey and others at the University of North Carolina.

Publication: Pediatrics (2006).

Participants:Total of 15,197 young adults, interviewed at age 18–26 as part of the third wave of a large longitudinal study called Add Health, which began in 1995 with a representative sample of over 20,000 U.S. adolescents.

Design: Participants were asked to report, confidentially (via headphones and a computer, a method that yields more accurate answers than face-to- face or written questions do), whether their caregivers had ever maltreated them. Questions were specific (e.g., “slapped, hit, or kicked”), and partici- pants indicated how often the behavior occurred (once, twice, or more).

Major conclusions: Maltreatment was common: One in four had been physi- cally abused. Each type of maltreatment was associated with mul- tiple health risks.

Comment: Although one would hope that these rates are overestimates, actual rates may be even higher, for three reasons: (1) Young adults tend to idealize their childhood; (2) the original participants were all in high school and had their parents’ permission to respond to the survey; and (3) the participants in this third wave of interviews were, on average, more advantaged than those who dropped out or could not be found.

post-traumatic stress disorder (PTSD) A delayed reaction to a trauma or shock, which may include hyperactivity and hyper- vigilance, displaced anger, sleeplessness, sudden terror or anxiety, and confusion between fantasy and reality.

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instance, child patients are reported for maltreatment three times more often in teaching hospitals (where ongoing education is part of the hospital’s mission) than in regular hospitals, where “child abuse and neglect are underidentified, under- diagnosed, and undercoded” (Rovi et al., 2004, p. 589). Would better reporting make a difference? It might have for a child known as B.V.

224 CHAPTER 8 ■ The Play Years: Biosocial Development

TABLE 8.2

Signs of Maltreatment in Children Aged 2 to 10

Injuries that do not fit an “accidental” explanation: bruises on both sides of the face or body; burns with a clear line between burned and unburned skin; “falls” that result in cuts, not scrapes

Repeated injuries, especially broken bones not properly tended

Fantasy play, with dominant themes of violence or sexual knowledge

Slow physical growth, especially with unusual appetite or lack of appetite

Ongoing physical complaints, such as stomachaches, headaches, genital pain, sleepiness

Reluctance to talk, to play, or to move, especially if development is slow

No close friendships; hostility toward others; bullying of smaller children

Hypervigilance, with quick, impulsive reactions, such as cringing, startling, or hitting

Frequent absences from school, changes of address, or new caregivers

Expressions of fear rather than joy on seeing the caregiver

Source: Adapted from Scannapieco & Connell-Carrick, 2005.

a case to study A Series of Suspicious Events

Three million reported cases of maltreatment per year in the United States seems like a huge number, yet most cases of neg- lect are not reported. Consider one team’s report on a child in a low-income family:

B.V., a 2-year-old male, was found lying face down in the bath- tub by an 8-year-old sent to check on him. He had been placed in the bathtub by his mother, who then went to the kitchen and was absent for approximately 10 minutes. B.V. was transported by ambulance to a local hospital. He was unresponsive and had a rectal temperature of 90 degrees Fahrenheit. After medical treat- ment, the child’s breathing resumed, and he was transported to a tertiary care hospital. B.V. remained in the pediatric intensive care unit for 9 days with minimal brain function and no response to any stimuli. He was then transferred to a standard hospital room where he died 2 days later. The mother refused to have an autopsy performed. Subsequently, the death certificate was signed by an attending physician, and cause of death was pneu- monia with anoxic brain injury as a result of near-drowning.

The CPS [Child Protective Services] worker advised B.V.’s mother that 10 minutes was too long to leave a 2-year-old in the bathtub unsupervised. B.V.’s mother replied that she had done it many times before and that nothing had happened. Further ex- amination of the medical chart revealed that prior to B.V.’s death, he had a sibling who had experienced an apparent life-threaten- ing event (previously termed a “near miss” sudden infant death syndrome). The sibling was placed on cardiac and apnea (breath- ing) monitors for 7 to 8 months. In addition, B.V. had been to the

children’s hospital approximately 2 weeks prior for a major injury to his big toe. B.V.’s toe had been severed and required numerous stitches. The mother stated that this incident was a result of the 4-year-old brother slamming the door on B.V.’s foot. Furthermore, B.V. had been seen in a different local hospital for a finger frac- ture the month before his death. None of the available reports indicate the mother’s history of how the finger fracture occurred.

[Bonner et al., 1999, pp. 165–166]

No charges were filed in this death. The team notes:

This case illustrates chronic supervisory neglect. . . . The series of suspicious events that preceded the death did not result in protective or preventive services for the family.

[Bonner et al., 1999, p. 166]

This case is indeed a chilling example of “chronic supervisory neglect.” Professionals who dealt with the family ignored many medical signs that something was wrong—the sibling’s “near- miss” SIDS, the fractured finger, and the severed toe. No mention is made of language, emotions, or social skills, which probably would have raised alarm as well.

Even after death, the neglect of neglect continued. No help was provided for the 8-year-old who found his dying brother or for the 4-year-old who reportedly severed the toddler’s toe. These children were also at high risk of maltreatment. Indeed, they had already been maltreated: Children are damaged by chronic feelings of helplessness and danger (De Bellis, 2001).

Especially for Nurses While weighing a 4-year-old, you notice several bruises on the child’s legs. When you ask about them, the child says nothing and the parent says the child bumps into things. What should you do?

➤Response for Urban Planners (from page 220): The adult idea of a park— a large, grassy open place—is not best for young children. For them, you would design an enclosed area, small enough and with adequate seating to allow caregivers to socialize while watching their children. The playground surface would have to be protective (since young children are clumsy), with equipment that encouraged both gross motor skills (such as climbing) and fine motor skills (such as sandbox play). Swings are not beneficial, since they do not develop many motor skills. Teenagers and dogs should have their own designated areas, far from the youngest children.

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Consequences of Maltreatment The impact of any child-rearing practice is affected by the cultural context. Certain customs (such as circumcision, pierced ears, and spanking) are considered abuse in some cul- tures but not in others, and their actual effects on children vary accordingly. Children suffer if their parents seem not to love them according to their community’s standards for parental love.

Maltreatment compromises basic health in every way (Hussey et al., 2006). Abused and neglected children are more often injured, sick, and hospitalized for reasons not di- rectly related to their maltreatment (Kendall-Tackett, 2002).

Many neglectful parents do not enroll their children in day-care centers or schools that would teach them well. Visits to a park, to a zoo, to the grandparents’ home, or to a neighbor child’s house are infrequent, since social isolation is a result as well as a cause of child maltreatment. Maltreated children learn less and suffer more.

Although biological and academic handicaps are substantial, deficits are even more apparent in the child’s social skills. Maltreated children often regard other people as hostile and exploitative; hence, they are less friendly, more aggressive, and more isolated than other children. The longer their abuse continues and the earlier it started, the worse their peer relationships are (Manly et al., 2001; Scannapieco & Connell-Carrick, 2005).

A life-span perspective reveals that all these deficits can continue lifelong. Maltreated children and adolescents are often bullies or victims or both. Adults who were severely maltreated in childhood (physically, sexually, or emotionally) often use drugs or alcohol to numb their emotions; they often enter unsupportive relationships, become victims or aggressors, sabotage their own careers, eat too much or too little, and generally engage in self-destructive behavior (M. G. Smith & Fong, 2004). From a developmental perspective, the worst consequences result from chronic neglect, which is least likely to be reported.

Three Levels of Prevention, Again Just as with injury control, there are three levels of prevention of maltreatment. The ultimate goal is to stop it before it begins. This is primary prevention; it focuses on the mesosystem and exosystem (see Chapter 1). Examples of primary- prevention conditions include stable neighborhoods; family cohesion; income equality; and measures that decrease financial instability, family isolation, and teenage parenthood.

Secondary prevention involves spotting the warning signs and intervening to keep a problematic situation from getting worse. For example, insecure attachment,

Abuse or Athletics? Four-year-old Budhia Singh ran 40 miles in 7 hours with adult marathoners. He says he likes to run, but his mother (a widow who allowed his trainer to “adopt” him because she could not feed him) has charged the trainer with physical abuse. The government of India has declared that Singh cannot race again until he is fully grown. If child, parent, and community approve of some activity, can it still be maltreatment?

Injuries and Abuse 225

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Physical abuse and neglect are most likely to be experienced by children who:

■ Are under age 6 ■ Have two or more siblings ■ Have an unemployed or absent father ■ Have a mother who did not complete high school ■ Live in a poor, high-crime neighborhood

All these risk factors were present for B.V. If he had not been poor, he might have had a private pediatrician, who might have noticed the danger he was in. If his mother had had fewer chil- dren and a supportive husband, she might have watched him in the tub. A higher level of education might have helped her understand how to cope. Neighbors and relatives might have helped. Instead, B.V. died.

➤Answer to Observation Quiz (from page 223): No. The number is actually 11.8 per 1,000. Note the little squiggle on the graph’s vertical axis below the number 11. This means that numbers between zero and 11 are not shown.

➤Response for Socially Aware Students (from page 221): Preschoolers from families at all income levels can have accidents, but Kathleen Berger’s SES allowed her to have a private pediatrician as well as the income to buy ipecac “just in case.” She also had a working phone and the education to know about Poison Control.

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Especially for the General Public You are asked to give a donation to support a billboard campaign against child abuse and neglect. You plan to make charitable contribu- tions totaling $100 this year. How much of this amount should you contribute to the billboard campaign?

especially of the disorganized type (described in Chapter 7), is a sign of a disrupted parent–child relationship. Someone needs to repair that interaction. Secondary prevention includes measures such as home visits by nurses or social workers, high-quality day care, and preventive medical treatment—all designed to help high-risk families.

Tertiary prevention includes everything intended to reduce the harm when mal- treatment has already occurred. Reporting and substantiating abuse are only the first steps. Action is needed. Someone must help the family or remove the child. If hospitalization is required, intervention should have begun much earlier. At that point, care is more expensive and hospitalization is longer than for other condi- tions (Rovi et al., 2004); in addition, lengthy hospitalization further damages the fragile parent–child bond.

Children fare better when they are secure in their environment, whether they live with their biological parents who have learned to provide good care, with a

Where’s Mom? Inside the shop, buying something for her baby. In many European towns, as here in Largs, Scotland, parents consider it beneficial to let the baby wait out- side and breathe fresh air rather than join them inside. In the United States, parents have been jailed for doing this. Can both cul- tures be right?

226 CHAPTER 8 ■ The Play Years: Biosocial Development

The Same Event, A Thousand Miles Apart: Fun with Grandpa Grandfathers, like those shown here in Japan and India, often delight their grandchildren. Sometimes, however, they protect them—either in kinship care, when parents are designated as neglectful, or as secondary prevention before harm is evident.

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foster family, or with an adoptive family. Permanency planning involves efforts by authorities to find a home that will nurture the child until adulthood (Waddell et al., 2004).

In foster care, children are officially removed from their parents’ custody and entrusted to another adult who is paid to nurture them. In 2004 more than half a million children in the United States were in foster care. About half of them were in a special version of foster care called kinship care, in which a relative of the maltreated child becomes the foster caregiver (U.S. Department of Health and Human Services, 2004). This estimate is for official kinship care; three times as many children are informally cared for primarily by relatives who are not their parents.

In the United States, most foster children are from low-income families; half are African American or Latino; and many have multiple physical, intellectual, and emotional problems (Pew Commission on Foster Care, 2004). Despite these prob- lems, children develop better in foster care (including kinship care) than with their original abusive families if a supervising agency screens foster families and provides ongoing financial and emotional support (Berrick, 1998).

However, many agencies are inadequate. One obvious failing is that many move children from one home to another for reasons that are unrelated to the child’s behavior or wishes. Foster children average three placements before finding a permanent home (Pew Commission on Foster Care, 2004).

Adoption is the preferred permanent option, but judges and biological parents are reluctant to release children for adoption, and some agencies reject all but “perfect” families—those headed by a heterosexual married couple who are middle class, and of the same ethnicity as the child, and in which the wife is not employed. Since a healthy permanency, not perfection, is the goal, most experts want adop- tion restrictions loosened, courts to act more quickly in the interests of the children, and permanent guardianship allowed if adoption is impossible.

SUMMING UP

As they move with more speed and agility, young children encounter new dangers, becoming seriously injured more often than older children. Three levels of prevention are needed. Laws and practices should be put in place to protect everyone (primary

Injuries and Abuse 227

permanency planning An effort by authori- ties to find a long-term living situation that will provide stability and support for a mal- treated child. A goal is to avoid repeated changes of caregiver or school, which can be particularly harmful for the child.

foster care A legal, publicly supported plan in which a maltreated child is removed from the parents’ custody and entrusted to another adult, who is paid to be the child’s caregiver.

kinship care A form of foster care in which a relative of a maltreated child becomes the approved caregiver.

Tertiary Prevention Adoption has been these children’s salvation, particularly for 9-year-old Leah, clinging to her mother. The mother, Joan, has five adopted children. Adoption is generally better than foster care for maltreated children, because it is a perma- nent, stable arrangement.STE

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➤Response for Nurses (from page 224): Any suspicion of child maltreatment must be reported, and these bruises are suspicious. Someone in authority must find out what is happening so that the parent as well as the child can be helped.

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228 CHAPTER 8 ■ The Play Years: Biosocial Development

7. Muscle control, practice, and brain maturation are also in- volved in the development of fine motor skills. Young children enjoy expressing themselves artistically, developing their motor skills as well as their self-expression.

Injuries and Abuse 8. Accidents are by far the leading cause of death for children, with 1- to 4-year-olds more likely to suffer a serious injury or pre- mature death than older children. Biology, culture, and commu- nity conditions combine to make some children more vulnerable.

9. Injury control occurs on many levels, including long before and immediately after each harmful incident, with primary, sec- ondary, and tertiary prevention. Laws seem more effective than educational campaigns. Close supervision is required to protect young children from their own eager, impulsive curiosity.

10. Child maltreatment typically results from ongoing abuse and neglect by a child’s own parents. Each year almost 3 million cases of child maltreatment are reported in the United States, almost 1 million of which are substantiated.

11. Health, learning, and social skills are all impeded by ongoing child abuse and neglect. Physical abuse is the most obvious form of maltreatment, but neglect is common and probably more harmful.

12. Foster care, including kinship care, is sometimes necessary. Permanency planning is needed because frequent changes are harmful to children. Primary and secondary prevention helps parents care for their children and reduces the need for tertiary prevention.

Body Changes 1. Children continue to gain weight and height during early child- hood. Many become quite picky eaters.

2. Culture, income, and family customs all affect children’s growth. Worldwide, an increasing number of children have unbal- anced diets, eating more fat and sugar and less iron and calcium than they need. Childhood obesity is increasingly common, be- cause children exercise less and snack more than children once did, laying the foundation for chronic adult illness.

Brain Development 3. Myelination is substantial during early childhood, speeding messages from one part of the brain to another. The corpus callo- sum becomes thicker and functions much better. The prefrontal cortex, known as the executive of the brain, is strengthened as well.

4. Brain changes enable more reflective, coordinated thought and memory; better planning; and quicker responses. Many brain functions are localized in one hemisphere of the brain. Left/right specialization is apparent in the brain as well as in the body.

5. The expression and regulation of emotions are fostered by sev- eral brain areas, including the amygdala, the hippocampus, and the hypothalamus. Abuse in childhood may cause an overactive amygdala and hippocampus, creating a flood of stress hormones that interfere with learning.

6. Gross motor skills continue to develop, so that clumsy 2-year- olds become 6-year-olds able to move their bodies in whatever ways their culture values and they themselves have practiced, as long as height and judgment are not required.

SUMMARY

myelination (p. 210) corpus callosum (p. 210) lateralization (p. 210) perseveration (p. 213) amygdala (p. 213) hippocampus (p. 213)

hypothalamus (p. 214) injury control/harm reduction

(p. 219) primary prevention (p. 220) secondary prevention (p. 220) tertiary prevention (p. 220)

child maltreatment (p. 222) child abuse (p. 222) child neglect (p. 222) reported maltreatment (p. 222) substantiated maltreatment

(p. 222)

post-traumatic stress disorder (PTSD) (p. 223)

permanency planning (p. 227) foster care (p. 227) kinship care (p. 227)

KEY TERMS

prevention); supervision, forethought, and protective measures should prevent mishaps (secondary prevention); and when injury occurs, treatment should be quick and effective and changes should be made to avoid repetition (tertiary prevention).

Each year, abuse or neglect is substantiated for almost a million children in the United States. About 2 million other cases are reported but not substantiated, and mil- lions more are not reported. Preventing maltreatment of all kinds is urgent but complex, because the source is often the family system and the cultural context, not a deranged stranger. Primary prevention includes changing the social context to ensure that parents protect and love their children. Secondary prevention focuses on families at high risk— the poor, the young, the drug-addicted. In tertiary prevention, the abused child is res- cued before further damage occurs.

■

➤Response for the General Public (from page 226): Maybe none of it. Educational campaigns seldom change people’s habits and thoughts, unless they have never thought about an issue at all. If you want to help prevent child abuse and neglect, you might offer free babysitting to parents you know who seem overwhelmed, or you might volunteer for a community group that helps troubled families.

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Summary 229

1. Keep a food diary for 24 hours, writing down what you eat, how much, when, how, and why. Then think about nutrition and eating habits in early childhood. Do you see any evidence in your- self of imbalance (e.g., not enough fruits and vegetables, too much sugar or fat, not eating when you are hungry)? Did your food habits originate in early childhood, in adolescence, or at some other time?

2. Go to a playground or other place where young children play. Note the motor skills that the children demonstrate, including abilities and inabilities, and keep track of age and sex. What dif- ferences do you see among the children?

3. Ask several parents to describe each accidental injury of each of their children, particularly how it happened and what the con- sequences were. What primary, secondary, or tertiary prevention measures would have made a difference?

4. Think back on your childhood and the friends you had at that time. Was there any maltreatment? Considering what you have learned in this chapter, why or why not?

APPLICATIONS

6. What conditions are best for children to develop their motor skills?

7. What are the differences among the three kinds of prevention?

8. What are the arguments for and against laws to protect chil- dren from injury?

9. Why might neglect be worse than abuse?

10. What are the advantages and disadvantages of foster care?

11. What are the advantages and disadvantages of kinship care?

1. How are growth rates, body proportions, and motor skills re- lated during early childhood?

2. Does low family income tend to make young children eat more or less? Explain your answer.

3. What are the crucial aspects of brain growth that occur after age 2?

4. How do emotions, and their expression, originate in the brain?

5. Why do public health workers prefer to speak of “injury control” or “harm reduction” instead of accidents?

KEY QUESTIONS

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9

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The Play Years: Cognitive Development

Iwas among dozens of adults on a subway who were captivated by alittle girl, perhaps 3 years old, with sparkling eyes and many braids. Shesat beside a large stranger, looking at her mother, who stood about 6feet to her left, holding onto a pole. The little girl repeatedly ducked her head behind the stranger and said, “You can’t see me, Mama,” unaware not only that her stockinged legs and shiny shoes stuck out in front of her but also that her whole body was constantly visible to her mother.

Like that little girl, every young child has much to learn. They are some- times egocentric, understanding only their own perspective. Among their developing ideas is a theory of mind, an understanding of how minds work (as in knowing that your mother can sometimes see you when you cannot see her).

Since children learn so much from age 2 to 6, developmentalists have gained a new respect for early education. No longer merely “day care,” or “home care,” early learning is now considered vital, whether it occurs at home or in a center.

The halting, simple sentences of the typical 2-year-old become the non- stop, complex outpourings of a talkative 6-year-old, who can explain almost anything. How does that happen? This chapter describes thinking and learn- ing from age 2 to 6, including remarkable advances in language as well as thought.

Piaget and Vygotsky Jean Piaget and Lev Vygotsky (introduced in Chapter 2) are justly famous for their descriptions of cognition. Their theories, especially in what they have to say about the eager learning of young children, are “compatible in many ways” (Rogoff, 1998, p. 681).

Piaget: Preoperational Thinking For Piaget, early childhood is the second of four stages of cognition. He termed cognitive development between the ages of about 2 and 6 preoperational intelligence, which goes beyond senses and motor skills (sensorimotor intelligence) to include language and imagination. Preoperational thinking is magical and self-centered; pre-operational means that the child is not yet ready for logical operations (or reasoning processes) (Inhelder & Piaget, 1964).

CHAPTER OUTLINE

� Piaget and Vygotsky

Piaget: Preoperational Thinking Vygotsky: Social Learning

� Children’s Theories

Theory-Theory Theory of Mind

� Language

Vocabulary IN PERSON: Mommy the Brat Grammar Learning Two Languages

� Early-Childhood Education

Child-Centered Programs Teacher-Directed Programs Intervention Programs Costs and Benefits

preoperational intelligence Piaget’s term for cognitive development between the ages of about 2 and 6; it includes language and imagination (in addition to the senses and motor skills of infancy), but logical, operational thinking is not yet possible.

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Obstacles to Logical Operations Piaget described four characteristics of thinking in early childhood, all of which make logic difficult: centration, focus on appearance, static reasoning, and irreversibility.

Centration is the tendency to focus on one aspect of a situation to the exclu- sion of all others. Young children may, for example, insist that lions and tigers seen at the zoo or in picture books cannot be cats, because the children “center” on the house-pet aspect of the cats they know. Or they may insist that Daddy is a father, not a brother, because they center on the role that each family member fills for them. The latter example illustrates a particular type of centration, ego-centration, which Piaget called egocentrism, literally self-centeredness. Egocentric children contemplate the world exclusively from their personal perspective.

Piaget did not equate egocentrism with selfishness. Consider, for example, a 3-year-old who chose to buy a model car as a birthday present for his mother, stubbornly convinced that she would be delighted. In fact, his “behavior was not selfish or greedy; he carefully wrapped the present and gave it to his mother with an expression that clearly showed that he expected her to love it” (Crain, 2005, p. 108).

A second characteristic of preoperational thought is a focus on appearance to the exclusion of other attributes. A girl given a short haircut might worry that she has turned into a boy. In preoperational thought, a thing is whatever it appears to be.

Third, preoperational children use static reasoning, assuming that the world is unchanging, always in the state in which they currently encounter it. A young boy might want the television turned off while he goes to the bathroom, assuming that when he returns, he can pick up the program exactly where he left off.

The fourth characteristic of preoperational thought is irreversibility. Preoper- ational thinkers fail to recognize that reversing a process sometimes restores what- ever existed before. A 3-year-old might cry because his mother put lettuce on his hamburger. Overwhelmed by his desire to have things “just right” (as explained in Chapter 8), he might reject the hamburger even after the lettuce is removed be- cause he believes that what is done cannot be undone.

Conservation and Logic Piaget devised many experiments demonstrating the constraints on thinking that result from preoperational reasoning. A famous set of experiments involved con- servation, the fact that the amount of something remains the same (is conserved) despite changes in its appearance.

Suppose two identical glasses contain the same amount of liquid, and the liquid from one glass is poured into a tall, narrow glass. If young children are asked whether one glass contains more liquid or they both contain the same, they will insist that the narrower glass, in which the liquid level is higher, has more.

All four characteristics of preoperational thought are evident in this mistake. Young children fail to understand conservation of liquids because they focus (center) on what they see (appearance), noticing only the immediate (static) condition. It does not occur to them that they could reverse the process and re-create the liquid level of a moment earlier (irreversibility). (See Figure 9.1 for other examples.)

Limitations of Piaget’s Research Notice that Piaget’s test of conservation required the child’s words, not actions. Other research has found that even 3-year-olds can distinguish appearance from reality if the test is nonverbal or playful (Sapp et al., 2000). Many children indi- cate that they know something via their gestures before they say it in words (Goldin-Meadow, 2006).

egocentrism Piaget’s term for children’s tendency to think about the world entirely from their own personal perspective.

centration A characteristic of preoperational thought in which a young child focuses (centers) on one idea, excluding all others.

focus on appearance A characteristic of preoperational thought in which a young child ignores all attributes that are not apparent.

static reasoning Thinking that nothing changes: Whatever is now has always been and always will be.

irreversibility The idea that nothing can be undone; the inability to recognize that something can sometimes be restored to the way it was before a change occurred.

conservation The idea that the amount of a substance remains the same (i.e., is con- served) when its appearance changes.

Especially for Parents Who Want Their Children to Eat Better How can Piaget’s theory help you encourage your child to eat?

232 CHAPTER 9 ■ The Play Years: Cognitive Development

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Piaget and Vygotsky 233

Tests of Various Types of Conservation

Type of Conservation

Initial Presentation

Preoperational Child’s AnswerTransformation Question

Volume Two equal glasses of liquid.

The taller one.Pour one into a taller, narrower glass.

Which glass contains more?

Number Two equal lines of checkers.

The longer one.Increase spacing of checkers in one line.

Which line has more checkers?

Matter Two equal balls of clay. The long one.Squeeze one ball into a long, thin shape.

Which piece has more clay?

Length Two sticks of equal length.

The one that is farther to the right.

Move one stick. Which stick is longer?

FIGURE 9.1

Conservation, Please According to Piaget, until children grasp the concept of conservation at (he believed) about age 6 or 7, they cannot understand that the transformations shown here do not change the total amount of liquid, checkers, clay, and wood.

CO UR

TE SY

O F

KA TH

LE EN

B ER

GE R

Demonstration of Conservation My youngest daughter, Sarah, here at age 53⁄4, demonstrates Piaget’s conservation-of-volume experiment. First, she examines both short glasses to be sure they contain the same amount of milk. Then, after the contents of one are poured into the tall glass and she is asked which has more, she points to the tall glass, just as Piaget would have ex- pected. Later she added, “It looks like it has more because it’s taller,” indicating that some direct instruction might change her mind.

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Researchers now believe that Piaget underestimated the conceptual ability of young children, just as he underestimated it in infants (Halford & Andrews, 2006). He designed his experiments to reveal what young children seemed not to under- stand, rather than to identify what they could understand, and he relied on the children’s words in an experimental setting rather than their nonverbal signs in a play context.

Vygotsky: Social Learning It is undeniable that young children’s thinking is often magical and self-centered. For many years, this aspect of cognition dominated descriptions of early childhood by developmentalists, especially Piaget.

Vygotsky was the first leading developmentalist to emphasize a second aspect of early cognition: Young children are not always egocentric; they can be very sensitive to the wishes and emotions of others. This second aspect emphasizes the social side of preschool thought, which contrasts with Piaget’s emphasis on the individual.

Children as Apprentices Vygotsky believed that every aspect of children’s cognitive development is embed- ded in a social context (Vygotsky, 1935/1987). Children are curious and observant. They ask questions—about how machines work, why weather changes, where the sky ends—assuming that others know the answers.

In many ways, a child is what Vygotsky called an apprentice in thinking, someone whose intellectual growth is stimulated and directed by older and more skilled members of society. The parents and older siblings are usually the child’s teachers (Maynard, 2002; Rogoff, 2003). If the child attends a day-care program, learning from “more capable peers” is central (C. Thompson, 2002).

According to Vygotsky, children learn because their elders do the following:

■ Present challenges ■ Offer assistance (not taking over) ■ Provide instruction ■ Encourage motivation

With the help of their mentors, children learn to think by means of their guided participation in social experiences and in explorations of their universe, with both the mentor and the child talking as well as acting. For example, children learning to draw or write or dance are quite willing to copy from one another. A child who is copied is not resentful but rather appreciates the recognition.

The reality that children are curious about everything, learn- ing and remembering whatever they experience, is evidence of cognition. The ability to learn (not the measure of what is known) indicates intelligence. Vygotsky (1935/1978) said: “What children can do with the assistance of others might be in some sense even more indicative of their mental development than what they can do alone” (p. 5).

apprentice in thinking Vygotsky’s term for a person whose cognition is stimulated and directed by older and more skilled members of society.

guided participation The process by which people learn from others who guide their experiences and explorations.

234 CHAPTER 9 ■ The Play Years: Cognitive Development

Guided Participation Through shared social activity, adults in every culture guide the development of their children’s cognition, values, and skills. Typically, the child’s curiosity and interests, rather than the adult’s planning for some sort of future need, motivate the process. That seems to be the case as this Guatemalan girl eagerly tries to learn her mother’s sewing skills.AV

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Especially for Aunts and Uncles It is a special family occasion, and you want to take presents to your nieces and nephews. What should you take?

➤Response for Parents Who Want Their Children to Eat Better (from page 232): It may help if you take each of the four characteristics of preoperational thought into account. Because of egocentrism, having a special place and plate might assure the child that this food is exclusively his or hers. Since appearance is important, food should look tasty. Since static thinking dominates, if something healthy is added (e.g., grate carrots into the cake, add milk to the soup), the addition should be done before the food is given to the child. In the reversibility example in the text, the lettuce should be removed out of the child’s sight and the “new” hamburger presented.

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Scaffolding As you saw in Chapter 2, Vygotsky believed that for each developing individual, there is a zone of proximal development (ZPD), which includes all the skills that the person can perform with assistance but cannot quite perform independ- ently. How and when children master their potential skills depends, in part, on the willingness of others to provide scaffolding, or temporary sensitive support, to help them traverse that zone.

Good caregivers scaffold often, teaching children to look both ways before crossing a street (while holding the child’s hand) or letting them stir the batter for a cake (perhaps stirring a few times themselves to make sure the ingredients are well mixed).

Scaffolding is particularly important for experiences that are directly cognitive —that is, ones that will produce better understanding of words and ideas. For example, adults reading to 3-year-olds usually provide excellent scaffolding— explaining, pointing, listening—toward the child’s ZPD in response to the child’s needs at the moment (Danis et al., 2000). The sensitive reader would never tell the child to be quiet and listen but might instead prolong the session by asking the child questions.

Siblings can also provide scaffolding. In one study in Chiapas, Mexico, 8-year- old Tonik taught his 2-year-old sister, Katal, how to wash a doll. After several min- utes of demonstrating and describing, Tonik continues:

Tonik: Pour it like this. (Demonstrates) Tonik: Sister, pour it. (Hands glass) Tonik: Look! Pour it. Katal: (Pours, with some difficulty) Tonik: Like that. (Approval) Katal: (Looks away) Tonik: It’s finished now.

[quoted in Maynard, 2002, p. 977]

Note that when Katal looked away, Tonik wisely declared the session finished. Such a response, not criticism, encourages the learner to participate in later ap- prenticeships. Motivation is crucial in early education—one reason why sensitive social interaction is so powerful.

Language as a Tool Vygotsky believed that words are used to build scaffolds, developing cognition. Just as a builder could not construct a house without tools, the mind needs lan- guage. Talking, listening, reading, and writing are tools to advance thought.

Language advances thinking in two ways. First, internal dialogue, or private speech, occurs when people talk to themselves, developing new ideas (Vygotsky, 1934/1987). Young children use private speech often, typically talking out loud to review, decide, and explain events to themselves (and, incidentally, to anyone else within earshot). Older preschoolers use private speech more selectively and effectively, sometimes in a whisper or even without any audible sound (Winsler et al., 2000). Adults use private speech quietly, and write down their ideas to help them think.

The second way in which language advances thinking, according to Vygotsky, is by mediating the social interaction that is vital to learning. This social mediation function of speech occurs during both formal instruction (when teachers explain things) and casual conversation.

Language used in social mediation is evident as children, guided by their men- tors, learn numbers, recall memories, and follow routines. Among the differences between 2-year-olds and 6-year-olds is that the latter can count objects, assigning

zone of proximal development (ZPD) Vygotsky’s term for the skills that a person can exercise only with assistance, not yet independently. ZPD applies to the ideas or cognitive skills a person is close to master- ing as well as to more apparent skills.

scaffolding Temporary support that is tai- lored to a learner’s needs and abilities and aimed at helping the learner master the next task in a given learning process.

private speech The internal dialogue that occurs when people talk to themselves (either silently or out loud).

Piaget and Vygotsky 235

social mediation A function of speech by which a person’s cognitive skills are refined and extended through both formal instruction and casual conversation.

Especially for Someone Teaching a Friend to Drive You want to teach a friend to drive using your car, but you fear a temper explosion or a crash. How would Vygotsky advise you to proceed?

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one number per item (called one-to-one correspondence), can remember accurately (although false memories can confuse anyone), and can verbalize scripts (such as the usual scenario for a birthday party or a restaurant meal).

Adult instruction and verbal encouragement are crucial for all these cognitive accomplishments (e.g., Hubbs-Tait et al., 2002; Mix et al., 2002). Thus, by age 3 or 4, children’s brains are mature enough to comprehend numbers, store memo- ries, and know routines, but whether or not a child actually demonstrates this understanding depends on family, school, and culture. Language is a key mediator between brain potential and what children actually understand and remember be- cause other people teach via the words children use to think (Haden et al., 2001; Schneider & Pressley, 1997).

SUMMING UP

Cognition develops rapidly from age 2 to 6. Children’s active search for understanding was first recognized by Piaget, who realized that children of this age are generally not capable of performing logical operations (which is why he called this period preoperational ). Their egocentrism limits their understanding and they center on only one thing at a time, focusing on appearance. Their thinking is static, not dynamic. They do not understand reversibility.

Vygotsky emphasized the social and cultural aspects of children’s cognition. He be- lieved that children must be properly guided as apprentices, within their zones of proxi- mal development. Language is a tool that mediates between the child’s curiosity and the mentor’s knowledge.

■

Children’s Theories Both Piaget and Vygotsky realized that children actively work to understand their world. Recently, many other developmentalists have attempted to show exactly how children’s knowledge develops. Children seek to explain what they experience, especially why and how people behave as they do. If no one provides satisfying explanations, they develop their own answers.

Theory-Theory One theory of cognitive development begins with the human drive to develop theories, a drive that is especially apparent in early childhood. The term theory- theory refers to the idea that children construct theories to explain everything they see and hear:

More than any animal, we search for causal regularities in the world around us. We are perpetually driven to look for deeper explanations of our experience, and broader and more reliable predictions about it. . . . Children seem, quite literally, to be born with . . . the desire to understand the world and the desire to discover how to behave in it.

[Gopnik, 2001, p. 66]

Thus, according to theory-theory, the best conceptualization of, and explanation for, mental processes in young children is that humans always seek reasons, causes, and underlying principles. Figure 9.2, with its narrative-style “recipe” for cooking a turkey, captures the essential idea of theory-theory: that children don’t want logical definitions but rather explanations of various things, especially things that involve them.

Exactly how are explanations sought in early childhood? In one study, Mexican American mothers kept detailed diaries of every question their 3- to 5-year-olds

theory-theory The idea that children attempt to explain everything they see and hear by constructing theories.

236 CHAPTER 9 ■ The Play Years: Cognitive Development

Especially for Adults Answering a 3-Year-Old’s Questions A characteristic of young children is that they ask questions, often frustrating adults by asking “Why?” getting an answer, and immediately asking “Why?” again. Now that you know that such questions are almost always about purpose, not science, how would you answer the question “Why is my brother bad?” or “Why is there night?”

➤Response for Aunts and Uncles (from page 234): Remember that preschool children focus on appearances and are egocentric. Whatever you give a 2- to 5-year-old must be seen as equal to any present you give another child. Thus, you would choose identical gifts (perhaps markers, toys, or articles of clothing), so that no child can compare presents and decide that you love another child more.

➤Response for Someone Teaching a Friend to Drive (from page 235): Use guided participation, and scaffold the instruction so it does not all come at once. Both you and your student might hold the steering wheel at first, and practice in a large, empty parking lot. Be sure to provide lots of praise and days of practice.

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asked and how the mothers responded (Kelemen et al., 2005; see Research Design). Generally, younger children asked more questions than older children, and more educated mothers heard (or recorded) more questions. This study focused partic- ularly on children’s curiosity and how adults respond.

Most of the questions were about human behavior and characteristics (see Fig- ure 9.3). For example, children asked, “Why do you give my mother a kiss?” “Why is my brother bad?” “Why do women have breasts?” and “Why are there Black kids?” Fewer questions were about nonliving things (“Why does it rain?”) or objects (“Why is my daddy’s car white?”).

Many questions concerned the un- derlying purpose of various natural phenomena, although parents usually responded as if children were asking about science instead. For example, when children asked why women have breasts, parents would tell them about hormones and maturation, not that breasts are for feeding babies.

Children’s Theories 237

A whole turkey 1 big bag full of a whole turkey (Get the kind with no feathers on,

not the kind the Pilgrims ate.) A giant lump of stuffin’ 1 squash pie 1 mint pie 1 little fancy dish of sour berries 1 big fancy dish of a vegetable mix 20 dishes of all different candies; chocolate balls, cherry balls,

good’n plenties and peanuts

Get up when the alarm says to and get busy fast. Unfold the turkey and open up the holes. Push in the stuffin’ for a couple of hours. I think you get stuffin’ from that Farm that makes it.

I know you have to pin the stuffin’ to the turkey or I suppose it would get out. And get special pins or use big long nails.

Get the kitchen real hot, and from there on you just cook turkey. Sometimes you can call it a bird, but it’s not.

Then you put the vegetables in the cooker—and first put one on top, and next put one on the bottom, and then one in the middle. That makes a vegetable mix. Put 2 red things of salt all in it and 2 red things of water also. Cook them to just 1⁄2 of warm.

Put candies all around the place and Linda will bring over the pies. When the company comes put on your red apron.

Percentage of Questions Asked by 3- to 5-Year-Olds, by Domain

Source: Adapted from Kelemen et al., 2005.

Human behavior 47%

Biology 31%

Other 4%

Nonliving natural things

9%

Objects 9%

FIGURE 9.3

Questions, Questions Parents found that most of their children’s questions were about human behavior—especially the parents’ behavior toward the child. Children seek to develop a theory to explain things, so the question “Why can’t I have some candy?” is not satisfactorily answered by “It’s almost dinnertime.”

Research Design Scientists: Deborah Kelemen and others.

Publication: Developmental Psychology (2005).

Participants: A total of 48 Mexican American mothers and their 3- to 5- year-olds. Most of the women were born in Mexico and all lived in central California at the time of the study.

Design: After an initial interview, the researchers phoned the mothers every two days for two weeks to hear what “Why?” or “How?” questions the chil- dren asked and what answers the children were given.

Major conclusion: Children ask many questions about the purpose of things and about human behavior; they seem less curious about inanimate objects.

Comment: These families were often bilingual, immigrant, and religious. These characteristics may not have affected the results, but replication is needed to find out for sure. Ideally, children’s actual questions would be tape-recorded, not simply reported by the mothers (whose reports might be distorted by unconscious biases).

FIGURE 9.2

Unfold the Turkey This recipe (from Smashed Potatoes, edited by Jane Martel) shows many characteristics of pre- school thought, among them literal interpretation of words (“Sometimes you can call it a bird, but it’s not”) and an uncertain idea of time (“Push in the stuffin’ for a couple hours”) and quantity (“A giant lump of stuffin’ ”).

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Theory of Mind Human mental processes—thoughts, emotions, beliefs, motives, and intentions— are among the most complicated and puzzling phenomena that we encounter every day. Adults seek to understand why people fall in love, or vote as they do, or make foolish choices. Children are puzzled about a playmate’s unexpected anger, a sibling’s generosity, or an aunt’s too-wet kiss.

To know what goes on in another’s mind, people develop a “folk psychology,” an understanding of others’ thinking called theory of mind. Theory of mind typically appears rather suddenly (Wellman et al., 2001), in “an important intellectual change at about 4 years” (Perner, 2000, p. 396).

Belief and Reality: Understanding the Difference Actually, theory of mind includes many concepts, some of which are difficult for much older children. However, a sudden leap in understanding does seem to occur at about age 4. What is it that children suddenly understand? Between the ages of 3 and 6, children come to realize that thoughts may not reflect reality. This idea leads to the theory-of-mind concept that people can be deliberately deceived or fooled—an idea that is beyond the understanding of most younger children, even when they have themselves been deceived.

Consider an experiment. An adult shows a 3-year-old a candy box and asks, “What is inside?” The child says, naturally, “Candy.” But the child has been tricked:

Adult: Let’s open it and look inside. Child: Oh . . . holy moly . . . pencils! Adult: Now I’m going to put them back and close it up again. (Does so) Now

. . . when you first saw the box, before we opened it, what did you think was inside it?

Child: Pencils. Adult: Nicky [friend of the child] hasn’t seen inside this box. When Nicky

comes in and sees it . . . what will he think is inside it? Child: Pencils.

[adapted from Astington & Gopnik, 1988, p. 195]

This experiment has become a classic, performed with thousands of children from many cultures. Three-year-olds almost always confuse what they know now with what they once thought and what someone else might think. Another way of describing this is to say that they are “cursed” by their own knowledge (Birch & Bloom, 2003), too egocentric to grasp other perspectives.

As a result, young children are notoriously bad at deception. They play hide- and-seek by hiding in the same place time after time, or their facial expression betrays them when they tell a fib. Closely related is their inability to change their minds (remember perseveration from Chapter 8), even when they recognize that they must think something new. With static reasoning (characteristic of preopera- tional thought), changing one’s mind is difficult.

Contextual Influences Recently, developmentalists have asked what, precisely, strengthens theory of mind at about age 4. Is this change more a matter of nature or of nurture, of brain maturation or of experience?

Neurological maturation is a plausible explanation. In one study, 68 children aged 21⁄2 to 51⁄2 were presented with four standard theory-of-mind situations, including a Band-Aid box that really contained pencils (similar to the candy-box experiment just described) (Jenkins & Astington, 1996). More than one-third of the children

238 CHAPTER 9 ■ The Play Years: Cognitive Development

theory of mind A person’s theory of what other people might be thinking. In order to have a theory of mind, children must real- ize that other people are not necessarily thinking the same thoughts that they themselves are. That realization is seldom possible before age 4.

Especially for Social Scientists Can you think of any connection between Piaget’s theory of preoperational thought and 3-year- olds’ errors in this theory-of-mind task?

➤Response for Adults Answering a 3-Year-Old’s Questions (from page 236): Do not talk about the toy the brother broke or explain the earth’s rotation! Instead, connect the answer to the child. You might say, “Your brother probably wishes he had your toy” or “There’s night so you know when it is time to go to sleep.”

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Children’s Theories 239

succeeded at all four tasks, and more than one-third failed at three or four. Age was the main factor: The 5-year-olds were most likely to succeed on all tasks, the 4-year-olds had mid- dling success, and the 3-year-olds were most likely to fail every time.

This age-related advance suggests that context is less cru- cial than maturation of the brain’s prefrontal cortex (Perner et al., 2002). Further evidence that brain maturation is a prereq- uisite for theory of mind is the fact that impaired brain func- tioning is the most likely cause of autism (see Chapter 11), and many autistic children are advanced in numerical under- standing but slow to develop theory of mind (Baron-Cohen, 1995).

Two other influences that are affected by context are key: language and siblings. Children with greater verbal fluency (at any age) are more likely to have a theory of mind. This is partly the result of experience, especially mother–child conversations that involve thoughts and wishes (Ruffman et al., 2002). Deaf children are delayed in develop- ing a theory of mind, probably because their language development is delayed (Lundy, 2002).

When the effects of both age and language ability are accounted for, a third im- portant factor emerges: having at least one older brother or sister (Jenkins & Astington, 1996). One researcher estimates that, in theory-of-mind development, “two older siblings are worth about a year of chronological age” (Perner, 2000, p. 383). The arguing, agreeing, competing, and cooperating that siblings normally do apparently lead children to understand that their own thinking is not shared by everyone.

A study comparing theory of mind among young children in preschools in Canada, India, Peru, Samoa, and Thailand found that the Canadian children were slightly ahead and the Samoan children were slightly be- hind, but across cultures most of the children in the study sample passed the false-belief tests (such as a culture-fair version of the one involving pencils in the candy box) by age 5 (see Figure 9.4). The researchers con- cluded that brain maturation was the primary factor in the acquisition of theory of mind but that language development and social interaction were also influential (Callaghan et al., 2005).

The child’s own logic and maturation are important (Piaget), but lan- guage and social interaction are mediators (Vygotsky) once the necessary brain structures are in place. In most cultures, “a certain amount of expe- rience hearing and participating in conversation” occurs by age 3, allow- ing theory of mind to develop (Callaghan et al., 2005, p. 382).

SUMMING UP

Scholars have recently noted that children develop theories to explain whatever they observe, and those theories do not necessarily spring from explanations given to them by adults. Children seem to be much more interested in the underlying purpose of events within the grand scheme of life; adults are more focused on immediate scientific causes. Many researchers have explored the development of theory of mind, the under- standing that other people can have thoughts and ideas that are unlike one’s own. Neurological maturation, linguistic competence, family context, and culture all affect the attainment of theory of mind at about age 4.

■

Road Rage? From their expressions, it looks as if this brother and sister may crash their toy jeep and cry, each blaming the other for the mishap. But a benefit of such sibling in- teractions is that they can advance theory of mind by helping children realize that people do not always think the same way.

© P

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Children’s Performance on False-Belief Tests

Number of children

5 10 15 20 25 30 35

Canada

India

Peru

Samoa

Thailand

Source: Callaghan et al., 2005.

Age 3: Pass Fail

Age 5: Pass Fail

FIGURE 9.4

Few at Age 3, Most by Age 5 The advantage of cross-cultural research is that it can reveal universal patterns. Although the number of children in each group is small (from 31 3-year- olds in Peru to 13 5-year-olds in Thailand), the pattern is obvious. Something changes at about age 4.

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Language Language is pivotal to cognition in early childhood, as we have seen in the ex- amples of Vygotsky’s social mediation and the development of theory of mind. Language is also the leading cognitive accomplishment during these years: 24-month-old children begin this period with short sentences and limited vocabu- lary, and 6-year-olds end it with the ability to understand and discuss almost any- thing (see Table 9.1).

Maturation and myelination added to extensive social interaction make age 2 to 6 the usual time for learning language. Indeed, scientists once thought that these years were a critical period, the only time when a first language could be mas- tered and the best time for learning a second or third language. This hypothesis has been disproven. Millions of older children and adults learn to be fluent in sec- ond languages (Bialystok, 2001; Hakuta et al., 2003).

Nonetheless, early childhood is a sensitive period for language learning—for rapidly and easily mastering vocabulary, grammar, and pronunciation. Young chil- dren are sometimes called “language sponges” because they soak up every drop of language they encounter.

They also talk a lot—to adults, to each other, to themselves, to their toys—unfazed by mispronunciation, misuse, stuttering, or other impediments to fluency. Note a crucial developmental asset as well: Language comes easily because, compared with most older children and adults, young children are not as self-conscious about what they say.

Vocabulary In childhood, new words are added rapidly. The average child knows about 500 words at age 2 and more than 10,000 at age 6. One scholar says that 2- to 6-year-olds learn 10 words a day (Clark, 1995); another estimates one word for every two waking hours from about age 2 to age 20 (Pinker, 1994). The naming explosion (explained in Chapter 6) be- comes a more general explosion, with new verbs, adjectives, adverbs, and conjunctions as well as many more nouns mastered during early childhood.

Precise estimates of vocabulary vary be- cause contexts are diverse; the estimates given here may be high. However, all researchers agree that vocabulary builds quickly and that most children could learn far more language than they do. Every child could probably become fluently bilingual if their context encouraged that.

Fast-Mapping How does the vocabulary explosion occur? After painstakingly learning one word at a time at age 1, children develop an interconnected set of categories for words, a kind of grid or mental map, which makes speedy vocabulary acquisition possible. The process is called fast-mapping (Woodward & Markman, 1998) because, rather than figuring out an exact definition after hearing a word used in several

240 CHAPTER 9 ■ The Play Years: Cognitive Development

TABLE 9.1

AT ABOUT THIS TIME: Language in Early Childhood

Approximate Age Characteristic or Achievement 2 years Vocabulary: 100–2,000 words

Sentence length: 2–6 words Grammar: Plurals, pronouns, many nouns, verbs, adjectives Questions: Many “What’s that?”questions

3 years Vocabulary: 1,000–5,000 words Sentence length: 3–8 words Grammar: Conjunctions, adverbs, articles Questions: Many “Why?” questions

4 years Vocabulary: 3,000–10,000 words Sentence length: 5–20 words Grammar: Dependent clauses, tags at ends of sentences

(“. . . didn’t I?” “. . . won’t you?”) Questions: Peak of “Why?” questions; also many “How?”

and “When?” questions

5 years Vocabulary: 5,000–20,000 words Sentence length: Some seem unending (“. . . and . . . who . . .

and . . . that . . . and . . .”) Grammar: Complex, sometimes using passive voice

(“Man bitten by dog”); subjunctive (“If I were . . .”) Questions: Include some about differences (male/female,

old/young, rich/poor)

critical period A time when a certain devel- opment must happen if it is ever to happen. For example, the embryonic period is critical for the development of arms and legs. It was once thought that early child- hood was the critical period for language learning, but today it is considered a sensitive period.

sensitive period A time when a certain type of development is most likely to happen and happens most easily. For example, early childhood is considered a sensitive period for language learning.

fast-mapping The speedy and sometimes imprecise way in which children learn new words by mentally charting them into categories according to their meaning.

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contexts, children hear a word once and tentatively stick it into one of the cate- gories on their mental language map.

Like more conventional mental mapping, language mapping is not always pre- cise. Thus, when asked where Nepal is, most people can locate it approximately (“in Asia”), but few can name each bordering country. Similarly, children quickly learn new animal names, for instance, because they are mapped in the brain close to already-known animal names. Thus, tiger is easy to map if you know lion. A trip to the zoo facilitates fast-mapping of dozens of animal words, especially since zoos scaffold such learning by placing similar animals together.

The benefit of knowing at least one word of a category is evident in a classic ex- periment. A preschool teacher taught a new word by saying, “Give me the chromium tray, not the red one” (Carey, 1985). Those children who already knew red quickly grasped the new word, chromium, and remembered it more than a week later. Those children who knew no color words did not remember the new word (a week later, they could not select a chromium object) because they were unable to map it (Mandler, 2004).

Another set of experiments began in cultures whose languages had only a few counting words: the equivalents of one, two, and many. People in such cultures were much worse at estimating quantity because they did not have the words to guide them (Gordon, 2004). Mapping and understanding a new number word, such as nineteen, is easier if one already knows a related word, such as nine.

Generally, the more linguistic clues children already have, the better their fast- mapping is (Mintz, 2005). To increase vocabulary, parents should talk to them often, adding new vocabulary (Hoff & Naigles, 2002). Alas, preschoolers also map words their parents would rather they didn’t, as I learned.

Language 241

What’s That? By far the best way for a par- ent to teach a young child new vocabulary is by reading aloud. Ideally, the interaction should be a very social one, with much point- ing and talking, as this Idaho pair demon- strate. If such experiences are part of her daily routine, this little girl not only will de- velop language but also will be among the first of her classmates to learn how to read.

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“Mommy the Brat”

Fast-mapping has an obvious benefit: It fosters quick acquisi- tion of vocabulary. However, it also means that children seem to know words merely because they use them when, in actuality, their understanding of the words’ meaning is quite limited.

Realizing that children often do not fully comprehend the meanings of words they use makes it easier to understand—and forgive—their mistakes. I still vividly recall an incident when my youngest daughter, then 4, was furious at me.

Sarah had apparently fast-mapped several insulting words into her vocabulary. However, her fast-mapping did not provide precise definitions or reflect nuances. In her anger, she called me first a “mean witch” and then a “brat.” I smiled at her inno-

cent imprecision, knowing the first was fast-mapped from fairy tales and the second from comments she got from her older sisters. Neither label bothered me, as I don’t believe in witches and my brother is the only person who can appropriately call me a brat.

But then Sarah let loose an X-rated epithet that sent me reel- ing. Struggling to contain my anger, I tried to convince myself that fast-mapping had left her with no real idea of what she had just said. “That word is never to be used in this family!” I sput- tered. My appreciation of the speed of fast-mapping was deep- ened by her response: “Then how come Rachel [her older sister] called me that this morning?”

in person

Words and the Limits of Logic Closely related to fast-mapping is logical extension: After learning a word, children use it to describe other objects in the same category. One child told her father she had seen some Dalmatian cows on a school trip to a farm. He understood her because he remembered that she had petted a Dalmatian dog the weekend before.

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Children use their available vocabulary to cover all the territory they want to talk about (Behrend et al., 2001). They use logic to figure out what words mean—for instance, deciding that butter comes from butterflies and birds grow from bird seed.

One child, jumping on a bed, knew that live with means reside in the same home.

Mother: Stop. You’ll hurt yourself. Child: No I won’t. (Still jumping)

Mother: You’ll break the bed. Child: No I won’t. (Still jumping)

Mother: OK. You’ll just have to live with the consequences. Child: (Stops jumping) I’m not going to live with the consequences.

I don’t even know them. [adapted from Nemy, 1998]

An experiment in teaching the names of parts of objects (e.g., the spigot of a faucet) found that children learned much better if the adults named the object that had the part, and then spoke of the part in the possessive (e.g., “See this butterfly? Look, this is its thorax”) (Saylor & Sabbagh, 2004). This finding shows that how a new word is presented affects the likelihood that a child will learn that word.

Young children have difficulty with words that express comparisons (such as tall and short, near and far, high and low, deep and shallow) because they do not understand that the meaning of these words depends on the context (Ryalls, 2000). Young children who know that one end of the swimming pool is the deep end might obey parental instructions to stay out of deep puddles by splash- ing through every puddle they see, insisting that none of them are deep.

Words expressing relationships of place and time—such as here, there, yester- day, and tomorrow—are difficult as well. More than one pajama-clad child has awakened on Christmas morning and asked, “Is it tomorrow yet?” A child told to “stay there” or “come here” may not follow instructions, partly because the terms are confusing.

One example of childlike understanding comes from Italian preschoolers who were discussing a war nearby. They seemed to understand the issues, advocating peace. But their words revealed their egocentrism. Giorgia, age 4, said, “The dad- dies, mommies, and children get their feelings hurt by war” (Abbott & Nutbrown, 2001, p. 123).

Grammar Chapter 6 noted that the grammar of language includes the structures, techniques, and rules that are used to communicate meaning. Word order and word repetition, prefixes and suffixes, intonation and emphasis—all are part of grammar.

By age 3, English-speaking children understand many aspects of grammar. They know word order (subject/verb/object), saying “I eat the apple,” not any of the 23 other possible sequences of those four words. They also use plurals, tenses (past, present, and future), and nominative, objective, and possessive pronouns (I/me/mine or my). They use articles (the, a, an) correctly, even though the use of articles in English has many complexities.

Parents’ input and encouragement, as well as their use of grammar, lead directly to faster and more correct language use by children (Barrett, 1999; Hoff & Naigles, 2002). In a study of twins (who are often delayed in grammar because they experience less individualized conversation), researchers found that the speed and scope of language learning depended on how much the parents spoke

242 CHAPTER 9 ■ The Play Years: Cognitive Development

Fangs for the Memories Museums, zoos, parks, farms, factories—all provide abundant opportunities for vocabulary building and concept formation. These parents may be teaching their children not only mountain lion but also habitat, carnivore, and incisors.

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➤Response for Social Scientists (from page 238): According to Piaget, preschool children focus on appearance and on static conditions (so they cannot mentally reverse a process). Further, they are egocentric, believing that everyone shares their point of view. No wonder they believe that they had always known that the candy box held pencils and that their friend would know that, too.

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to each twin (Rutter et al., 2003). Some parents speak more to one twin than the other, and that difference affects language development.

Each specific aspect of language develops differently, because many genetic and environmental influences have an impact, and no two children have the same influences. Genes may be more influential for expressive than for receptive language, since the latter is more dependent on experience (Kovas et al., 2005). Grammar is strongly influenced by experience.

Young children learn grammar so well that they tend to apply rules when they should not. This tendency, called overregularization, creates trouble when a language includes many exceptions, as English does. An example involves one of the first grammatical rules that English-speaking children apply: the addition of a final -s to form the plural of a noun. Many young children overregularize, talking about foots, tooths, sheeps, and mouses.

A fascinating aspect of the increasing intelligence of young children is that many of them first say words correctly and then, when they understand the rule, start making overregularizing mistakes. Although even the first sentences show some understanding of grammar, it takes many years before children use all the grammar structures of their native language correctly (Tomasello, 2006).

Learning Two Languages In today’s world, bilingualism is an asset, even a necessity. Yet as they grow up, language-minority children (those who speak a language that is not the dominant language of their nation) are at a disadvantage in almost every measure. They are more likely to do poorly in school, to feel ashamed, to become unemployed as adults, and so on (see Chapter 12). Learning the majority language is crucial for them, but how should this learning happen?

What Is the Goal? The first question that must be answered is, What is the goal of having a second language? Parents, teachers, and the public often disagree. Should young children become bilingual, learning two distinct languages? Some say no, arguing that young children need to become proficient in one, and only one, language and that trying to teach them two languages might confuse them. Others say yes, arguing that everyone should learn at least two languages and that the language-sensitive years of early childhood are the best time for it.

The second argument has more research support. Remarkably, soon after the vocabulary explosion, young children are able to master two languages’ distinct sets of words and grammar, with each lan- guage’s characteristic pauses, pronunciations, into- nations, and gestures (Bates et al., 2001; Mayberry & Nicoladis, 2000). Adults who are bilingual can use one language and temporarily inhibit the other, experiencing no confusion, thanks to a specific area of the brain that stores language and uses the appro- priate words (Crinion et al., 2006).

Young children have difficulty with pronunciation in every language, but this does not slow down their learning of a second language, as it does for adults. When expressing themselves, many of them transpose sounds (magazine becomes mazagine), drop conso- nants (truck becomes ruck), convert difficult sounds

overregularization The application of rules of grammar even when exceptions occur, so that the language is made to seem more “regular” than it actually is.

Language 243

Tiene Identificación Lista Are you pleased or angered by this bilingual sign at a school in Chelsea, Massachusetts, that serves as a polling place on election day? In this election, voters were deciding whether or not to elimi- nate government funding for bilingual educa- tion. Those who favored immersion argued that signs like this one would soon become unnecessary if children were taught only in English. Those who favored bilingual education held that without it, children from minority- language families would be likely to drop out of school before mastering any language.

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244 CHAPTER 9 ■ The Play Years: Cognitive Development

( father becomes fadder), and make other errors. But they can hear better than they can talk (receptive more than expressive). For example, my daughter Rachel at age 4 asked for a “yeyo yayipop.” Her father said, “You want a yeyo yayipop?” She replied, “Daddy, sometimes you talk funny.”

Bilingualism, Cognition, and Culture Since language is integral to culture, bilingualism is embedded in emotions of ethnic pride and fear. This reality hampers developmental research. One group of researchers explains:

A question of concern to many is whether early schooling [in the play years] in English for language minority children harms the development and/or mainte- nance of their mother tongue and possibly children’s language competence in general. . . . [The] debate quickly and unfortunately becomes . . . hampered by extreme and emotional political positions.

[Winsler et al., 1999, p. 350]

Research finds that bilingualism has both advantages and disadvantages. Sup- porters point out, correctly, that children who speak two languages by age 5 are less egocentric in their understanding of language and more advanced in their theory of mind. Opponents point out, also correctly, that bilingual children often are less fluent in one or both languages, slowing down reading as well as other linguistic skills (Bialystok, 2001).

This last fact makes many who speak the dominant language strive to have every child learn that language. This issue is of particular importance in California, where more than half of all public school children have parents who are immi- grants. Many such parents find that their children make a language shift, becoming more fluent in their new language than in their home language (Min, 2000; S.-L. C. Wong & M. G. Lopez, 2000).

It is not unusual for 5-year-olds to understand their parents’ language but re- fuse to speak it, especially if their parents understand the dominant language. Nor is it unusual for adults to depend on a child as interpreter when they deal

with monolingual bureaucrats. This dependency, which amounts to a role reversal, makes practical sense, but it widens the gap between child and parent. (Even native- born monolingual families have a generational and cohort parent–child gap.)

Language shift and role reversal are unfortunate, not only for the child and the parents but also for the society. Having many bilingual citizens is a national strength, and respect for family traditions is a bulwark against ado- lescent rebellion. Yet young children are preoperational: They center on the immediate status of their parents and their language, on appearances more than past history or future benefits. No wonder many shift toward the domi- nant language.

Again, what is the goal of second-language learning? Parents are reluctant to deprive children of their roots, heritage, and identity, and yet they know that speaking, reading, and writing the dominant language are necessary for success (Suarez-Orozco & Suarez-Orozco, 2001). Many adults who are proud of their home language criti- cize members of their ethnic group who have “lost” their heritage language. But they also know that their children

One Family’s Multiculturalism One of the first cultural preferences to travel successfully is food, and Italian cuisine is one of the world’s most popular. This family lives in New York, the parents were born in Taiwan, their chil- dren are learning to speak both Chinese and English—and they all love pepperoni pizza.

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Especially for Immigrant Parents You want your children to be fluent in the language of your family’s new country, even though you do not speak that language well. Should you speak to your children in your native tongue or in the new language?

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will face discrimination if they speak with a “foreign” accent and are less than fluent in the dominant language.

The best solution seems to be for every child to become a balanced bilingual, fluent in two languages, speaking both so well that no audible hint suggests the other language. Is balanced bilingualism possible? Yes. In many nations, during these sensitive play years, children become fluent in two or more languages.

Constant Change The basics of language learning—explosion, fast-mapping, overregularization, ex- tensive practice—apply to bilingual learning. Parents who want a child to learn two languages need to intensify the child’s exposure to both languages.

Fortunately, children have a powerful urge to communicate and a readiness to learn as much as they can. This was dramatically illustrated by children in Nicaragua at a boarding school for the deaf (Siegal, 2004). Their teachers tried to teach spoken Spanish and used no sign language. (This strategy is no longer com- mon, since it is now clear that deaf children learn best if they are taught sign lan- guage from infancy. However, war delayed the teachers’ awareness of this finding.)

The children in Nicaragua invented their own sign language, using it among themselves and teaching it to the new arrivals. Their created language flourished, with each new generation of children refining it. Younger children were more flu- ent than older ones because they built on what had already been invented, adding new gestures.

Similarly, established languages continually change. In English in the past few decades, the word Negro gave way to Black, which was soon replaced by African American. New terms include hip-hop, e-mail, DVD, spam, blog, cell (phone), rap (music), buff (in shape), and hundreds more. Words from other languages have become basic English vocabulary, such as salsa, loco, amour, kowtow, and mensch. Some key terms in this book, doula and kwashiorkor among them, originated in other languages. Young people learn such changes before adults do.

SUMMING UP

Children aged 2 to 6 have impressive linguistic talents. They explode into speech, from about a hundred words to many thousands, from halting baby talk to fluency. Fast- mapping and grammar are among the sophisticated devices they use, strategies that can backfire. No other time in the entire life span is as sensitive to language learning, especially to mastering pronunciation. Children can readily learn two languages during these years. Extensive exposure to both languages is necessary to become a balanced bilingual.

■

Early-Childhood Education A hundred years ago children had no formal education until first grade, which is why it was called “first” and why younger children were called “preschoolers.” Today most 3- to 5-year-olds in developed nations are in school (see Figure 9.5 for U.S. trends), partly because research “documents the rapid development and great learning potential of the early years” (Hyson et al., 2006, p. 6).

Names of early educational institutions differ (such as preschool, nursery school, day care, pre-primary), but names do not indicate the nature of a program. We will consider three clusters: child-centered, teacher-directed, and intervention programs.

Early-Childhood Education 245

balanced bilingual A person who is fluent in two languages, not favoring one or the other.

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Child-Centered Programs Many programs are developmental, or child-centered, stressing children’s devel- opment and growth. This approach stresses children’s need to play and explore rather than to follow adult directions (Weikart, 1999). Many child-centered pro- grams use a Piaget-inspired model that allows children to discover ideas at their own pace. The physical space and the materials—dress-up clothing, art supplies,

puzzles, blocks of many sizes, and other toys—are or- ganized to encourage self-paced exploration.

Many child-centered programs encourage artistic ex- pression. Some educators argue that young children “are all poets” in that they are gifted in seeing the world more imaginatively than older people do. According to advocates of child-centered programs, this peak of cre- ative vision should be encouraged; children should be given lots of opportunities to tell stories, draw pictures, dance, and make music for their own delight (Egan & Ling, 2002).

Child-centered programs also show the influence of Vygotsky, who thought that children learn from other children, with adult guidance. For example, in order to learn number skills, classrooms have games that include math (counting objects, keeping score), routines that use measurements (daily calendars, schedules), and number guidelines (only three children in the blocks corner, two volunteers to get the juice).

246 CHAPTER 9 ■ The Play Years: Cognitive Development

Percentage of U.S. 3-, 4-, and 5-Year-Olds Enrolled in Preprimary Programs

Percent

50

40

30

20

10

19701965 1975 1980 1985 1990 1995 2004

Year

Source: Snyder et al., 2004, p. 65; U.S. Bureau of the Census, 2006.

90

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3-year-olds

4-year-olds

5-year-olds

FIGURE 9.5

Changing Times As research increasingly finds that preschool education provides a foundation for later learning, more and more young children are in educational programs.

“We teach them that the world can be an unpredictable, dangerous, and sometimes frightening place, while being careful

not to spoil their lovely innocence. It’s tricky.”

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Montessori Schools One type of preschool that is child-centered began a hundred years ago, when Maria Montessori opened nursery schools for poor children in Rome. She believed that children needed structured, individualized projects to give them a sense of accomplishment, such as completing particular puzzles, using a sponge and water to clean a table, and drawing shapes.

Like Piaget (her contemporary), Montessori (1936/1966) realized that children have different thoughts and needs from adults. They learn from activities that adults might call play, and teachers should provide tasks that dovetail with the cognitive eagerness of the child. For example, because they have a need for order, for language learning, and for using all their senses, children will learn from exer- cises that allow them to develop these skills.

Today’s Montessori schools still emphasize individual pride and accomplish- ment, presenting many literacy-related tasks (such as outlining letters and looking at books) to the children at age 4 or so (Lillard, 2005). Many tasks differ from those Montessori developed, but the underlying philosophy is the same. Children collaborate with each other and do not sit quietly while a teacher instructs them. That is what makes this child-centered, although some things children enjoy (pre- tend play, for example) are not Montessori.

The goal is for the children to feel proud of themselves and engaged in learning. Many aspects of Montessori’s philosophy are in accord with current developmen- tal research, and that is one reason this kind of school remains popular in many nations. A study of 5-year-olds in inner-city Milwaukee who were chosen by lottery to attend Montessori programs found that they were better at pre-reading and early math tasks, as well as at theory of mind, than a group of their peers who had not been selected (Lillard & Else-Quest, 2006).

The Reggio Emilia Approach Another form of early-childhood education is called the Reggio Emilia approach because it was inspired by a program pioneered in the Italian town of that name, where today 13 infant–toddler centers and 21 preschools are funded by the city. Almost all local parents want their children to participate; there is a waiting list, and more centers are planned.

In Reggio Emilia, every preschooler is encouraged to master skills not usually seen in American schools until age 7 or so, such as writing and using tools, but no child is required to engage in such learning (Edwards et al., 1998). There is no large-group instruction, with formal lessons in, say, forming letters or cutting paper. Children are seen as “rich and powerful learners” and as “competent, creative individuals” (Abbott & Nutbrown, 2001, pp. 24, 47), each with his or her own learning needs and artistic drive.

Appreciation of the arts is evident not only in the children’s activities but also in the physical design of the schools. Every Reggio Emilia school has a large central room where children gather, with floor-to-ceiling windows open to a spacious, plant-filled playground. Big mirrors are part of every school’s décor (again fostering individuality), and children’s art is displayed on white walls and hung from high ceilings. Among the characteristics of Reggio Emilia programs (now evident in every developed nation) are a low teacher/child ratio, ample space, and abundant materials.

One of the distinctive features of the curriculum is that a small group of children become engaged in long-term projects of their choosing. Such projects foster the children’s pride in their accomplishments (which are displayed for all to admire) while teaching them to plan and work together.

Early-Childhood Education 247

➤Response for Immigrant Parents (from page 244): Children learn by listening, so it is important for you to speak with them often, and it is probably best to do so in both languages. Depending on how comfortable you are with the new language, you might prefer to read to your children, sing to them, and converse with them primarily in your native language and find a good preschool where they will learn the new language. The worst thing you could do would be to restrict speech in either tongue.

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Teachers have 6 hours of work time each week without the children, which they spend planning activities, having group discussions, and talking to parents. Parental involvement is expected: They teach in special subject areas, meet with one another, and receive frequent reports, often with photographs, written observations, and their child’s artwork. The entire town is proud of their children and schools.

Teacher-Directed Programs Unlike Reggio Emilia, some programs stress academics taught by the teacher to the entire class. The curriculum teaches children letters, numbers, shapes, and colors, as well as how to listen to the teacher and sit quietly. Praise and other reinforce- ments are given for good behavior, and time-outs (brief separation from activities) are punishments.

In teacher-directed programs, there is a clear distinction between the serious work of schooling and the cozy play of home. As one German boy explained:

So home is home and kindergarten is kindergarten. Here is my work and at home is off-time, understand? My mum says work is me learning something. Learning is when you drive your head, and off-time is when the head slows down.

[quoted in Griebel & Niesel, 2002, p. 67]

The teachers’ goal is to make all children “ready to learn” when they enter ele- mentary school. Some of these programs explicitly teach basic skills, including reading, writing, and arithmetic, sometimes with the teacher asking questions that all the children answer together. Children are given practice in forming letters, sounding out words, counting objects, and writing their names. If a 4-year-old learns to read, that is success. (In a developmental program, it might arouse suspi- cion that the child was not being allowed enough time to play.) Many teacher- directed programs were inspired by behaviorism, which emphasizes step-by-step learning and repetition.

The contrast between child-centered and teacher-directed philosophies is evi- dent in many areas, not only in lessons but also in social interactions. For instance, if one child bothers another child, should the second child tell the teacher, or

248 CHAPTER 9 ■ The Play Years: Cognitive Development

Another Place for Children High ceilings, uncrowded play space, varied options for art and music, a glass wall revealing trees and flowers—all these features reflect the Reggio Emilia approach to individualized, creative learning for young children. Such places are rare in nations other than Italy.

Observation Quiz (see answer, page 250): How many children appear in this photograph and how many are engaged in creative expression?

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should the two children work it out by themselves? If one child bites another, should the biter be isolated, reprimanded, or—as sometimes happens—should the victim be allowed to bite back? Each preschool has rules for such situations, which vary because of contrasting philosophies.

Intervention Programs Developmental scientists, linking research findings and practical applications, have discovered that early childhood is a prime learning period. It is also evident that some children learn much more than others. Five-year-olds differ dramati- cally in their ability to learn, talk, and even listen. The main reason is thought to be exposure to language and other learning opportunities that some parents provide and others do not (Hart & Risley, 1995).

Many nations try to narrow the gap by offering high-quality early education. Some nations (e.g., China, France, Italy, and Sweden) make programs available to all children; others vary (for example, in the United States, Oklahoma, and some other states provide full-day kindergarten and preschool education for all children, while other states provide only a few hours a day for those who are particularly needy).

Head Start In the United States, the most widespread early-childhood-education program is Project Head Start, which began in 1965 and continues to this day. This federal pro- gram was designed for low-income or minority children who were thought to need a “head start” on their education. The quality and results of Head Start programs vary from place to place. Some long-term effects are unknown, because scientific evaluation was not included in the original planning (Phillips & White, 2004).

Nevertheless, Head Start has provided half-day education for millions of 3- to 5-year-olds, boosting their social and learning skills at least temporarily, and has probably provided long-term benefits as well (Zigler et al., 1996). Some programs are now 6 hours long rather than 3, because researchers realize that learning cor- relates with the length of school time.

There are many problems in evaluating Head Start. Over the decades, its goals have been diffuse and varied, from lifting families out of poverty to promoting lit- eracy, from providing dental care and immunizations to teaching standard English. Some teachers practice child-centered education and others prefer a teacher- directed approach; some consider parents part of the problem and others regard parents as allies. In any case, intervening with parents has proven difficult (Powell, 2006).

Many of the early Head Start programs had no spe- cific curriculum or goals, which made valid evaluation impossible (Whitehurst & Massetti, 2004). An added problem has been the political turmoil that surrounds the topics of poverty, government programs, and the education of young children in the United States. The federal government has continued to fund Head Start year after year, partly because early education is proven to be beneficial in dozens of ways, but the pro- gram’s priorities and direction have changed continu- ally as the political winds have shifted (Zigler & Styfco, 2004).

Early-Childhood Education 249

Learning Is Fun The original purpose of the Head Start program was to boost disadvan- taged children’s academic skills. The most en- during benefits, however, turned out to be improved self-esteem and social skills, as is evident in these happy Head Start partici- pants, all crowded together.

Observation Quiz (see answer, page 251): How many of these children are in close physical contact without discomfort or disagreement?

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Especially for Parents In trying to find a preschool program, what should a parent look for?

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Experimental Programs The same social imperatives that led to Head Start also led to several intensive programs (involving many hours and years, with cognitive emphasis) that have been well evaluated through longitudinal research. Three projects in particular have excellent follow-up data: one in Michigan, called Perry or High/Scope (Schweinhart & Weikart, 1997; Schweinhart et al., 2005); one in North Carolina, called Abecedarian (Campbell et al., 2001); and one in Chicago, called Child– Parent Centers (Reynolds, 2000; Reynolds et al., 2004).

All three programs enrolled children from low-income families for several years before kindergarten, all compared experimental groups of children with matched control groups, and all reached the same conclusion: Early education can have substantial long-term benefits, which become apparent when the children are in the third grade or later.

Children in these three programs scored higher on math and reading achieve- ment tests by age 10 than did other children from the same backgrounds, schools, and neighborhoods. They were significantly less likely to be placed in special classes for slow or disruptive children or to repeat a year of school. In adolescence, they had higher aspirations and a greater sense of achievement and were less likely to be mistreated. As young adults, they were more likely to attend college and less likely to go to jail.

All three research projects found that direct cognitive training (not simply let- ting children play), with specific instruction in various school-readiness skills, was useful as long as each child’s needs and talents were considered. The curriculum was neither child-centered nor teacher-directed, but a combination. Parents were engaged with the child’s learning.

Although these programs were expensive (perhaps as much as $15,000 annu- ally per child in 2007 dollars), many believe that the decreased need for special education and other social services eventually makes such programs a wise invest- ment. Indeed, one economist calculates that governments eventually spend at

250 CHAPTER 9 ■ The Play Years: Cognitive Development

Learning from One Another Every nation creates its own version of early education. In this scene at a nursery school in Kuala Lumpur, Malaysia, note the head coverings, uniforms, bare feet, and absence of boys. None of these elements would be found in most early-childhood education classrooms in North America or Europe.

Observation Quiz (see answer, page 252): What seemingly universal aspects of child- hood are visible in this photograph? PAU

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➤Answer to Observation Quiz (from page 248): Eight children, and all of them are engaged in creative projects—if the boy standing at right is making music, not just noise, with that cymbal.

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least five times more per person when children do not have the benefit of an in- tensive preschool program (Lynch, 2004). Children from low-income families who did not attend preschool have higher rates of many costly conditions later in life: special education (four times more expensive per student per year); unemploy- ment (no taxes); and even imprisonment ($150,000 per inmate per year).

Costs and Benefits The financial aspect may be especially significant. For many early-childhood edu- cators, Reggio Emilia is the gold standard because the teacher/child ratio is low and the physical space is luxurious, but the cost per child for such a program is about twice that of most other types of preschool care.

Since parents pay the bulk of the cost of preschool education in the United States (except for some intervention programs), Reggio Emilia is beyond the means of most families. Child-centered programs open to all children may be fea- sible only in places with community support and a low birth rate (like Italy, where most families have only one child).

A key finding from all the research is that the quality of early-childhood educa- tion counts. The most recent reauthorization of Head Start emphasizes educational quality and evaluative research (Lombardi & Cubbage, 2004). Comparisons of programs find that the specific curricula and philosophy matter less than teachers who know how to respond to the needs of young children. Generally, an educa- tional, center-based program is better than family day care or home care, but high- quality home care is better than a low-quality day-care center (Clarke-Stewart & Allhusen, 2005).

Some characteristics of quality care have been described in Chapter 7: safety, adequate space and equipment, a low adult/child ratio, positive social interactions among children and adults, and trained staff (and educated parents) who are likely to stay in the program. Continuity helps, for the child as well as for the adults. One of the best questions that parents comparing options can ask is, “How long has each staff member worked at this center?”

Curriculum is also important, especially by age 4 or 5. Best may be programs with an emphasis on learning, reflected in a curriculum that includes extensive practice in language, fine and gross motor skills, and basic number skills. Such programs may be found in child-centered or teacher-directed schools. As this chapter emphasizes, young children love to learn and can master many skills and ideas, as long as adults do not expect them to think and behave like older children.

Beyond that, history teaches that new research will find additional cognitive potential among 2- to 6-year-olds and additional strategies to develop that poten- tial. Valid evaluation (longitudinal comparisons with experimental and control groups) are still rare. Some readers of this book will undertake the research and staff the schools that will update our view of cognition in childhood.

SUMMING UP

Research, particularly on preschool programs for children in low-income families, has proved that high-quality early education benefits children, who improve in language, in social skills, and in prospects for the future (Clarke-Stewart & Allhusen, 2005). A variety of programs, including child-centered (Montessori and Reggio Emilia) and teacher- directed are available—although sometimes very expensive. Nations, states, and parents differ in what they seek from early education for their children, and programs vary in teacher preparation, curriculum, physical space, and adult/child ratios.

■

Early-Childhood Education 251

➤Answer to Observation Quiz (from page 249): All five—not four (look again at the right-hand side of the photograph)!

➤Response for Parents (from page 249): There is much variation. None fit every parent’s values. However, children should be engaged in learning, not allowed to sit passively or to squabble with one another. Before deciding, parents should look at several programs, staying long enough to see the children in action and the teachers showing warmth and respect for the children.

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252 CHAPTER 9 ■ The Play Years: Cognitive Development

Piaget and Vygotsky 1. Piaget stressed the egocentric and illogical aspects of thought during the play years. He called this stage preoperational thought because young children often cannot yet use logical operations to think about their observations and experiences.

2. Young children, according to Piaget, sometimes focus on only one thing (centration) and see things only from their own view- point (egocentrism), remaining stuck on appearances and on cur- rent reality. They cannot understand that things change, actions can be reversed, and other people have other perspectives.

3. Vygotsky stressed the social aspects of childhood cognition, noting that children learn by participating in various experiences, guided by more knowledgeable adults or peers. That guidance assists learning within the zone of proximal development, which encompasses the knowledge and skills that the child has the potential to learn.

4. According to Vygotsky, the best teachers use various hints, guidelines, and other tools to provide the child with a scaffold for new learning. Language is a bridge of social mediation between the knowledge that the child already has and the learning that the society hopes to impart. For Vygotsky, words are a tool for learning that both mentor and child use.

Children’s Theories 5. Children develop theories, especially to explain the purpose of life and their role in it. Among these theories is theory of mind— an understanding of what others may be thinking. Notable ad- vances in theory of mind occur at around age 4. Theory of mind is partly the result of brain maturation, but a child’s language and experiences (in the family and community) also have an impact.

Language 6. Language develops rapidly during early childhood, which is a sensitive period but not a critical one for language learning. Vocabulary increases dramatically, with thousands of words added between ages 2 and 6. In addition, basic grammar is mastered.

7. Many children learn to speak more than one language. Ideally, children become balanced bilinguals, equally proficient in two languages, by age 6.

Early-Childhood Education 8. Organized educational programs during early childhood ad- vance cognitive and social skills, although specifics vary a great deal. Montessori and Reggio Emilia are two child-centered pro- grams that began in Italy and now are offered in many nations. Behaviorist principles led to many specific practices of teacher- directed programs.

9. Head Start is a government program that generally helps low- income children. Longitudinal research on three other programs for low-income children has demonstrated that early-childhood education reduces the likelihood of later problems. Graduates of these programs are less likely to need special education and more likely to become law-abiding, gainfully employed adults.

10. Although many preschool programs are successful, the qual- ity of early education matters. Children learn best if there is a clear curriculum and if the adult–child ratio is low. The training and continuity of early-childhood teachers are also important.

preoperational intelligence (p. 231)

centration (p. 232) egocentrism (p. 232) focus on appearance (p. 232) static reasoning (p. 232)

irreversibility (p. 232) conservation (p. 232) apprentice in thinking (p. 234) guided participation (p. 234) zone of proximal development

(ZPD) (p. 235)

scaffolding (p. 235) private speech (p. 235) social mediation (p. 235) theory-theory (p. 236) theory of mind (p. 238) critical period (p. 240)

sensitive period (p. 240) fast-mapping (p. 240) overregularization (p. 243) balanced bilingual (p. 245)

SUMMARY

KEY TERMS

➤Answer to Observation Quiz (from page 252): Three aspects are readily apparent: These girls enjoy their friendships; they are playing a hand-clapping game, some version of which is found in every culture; and, most important, they have begun the formal education that their families want for them.

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Summary 253

6. How does fast-mapping apply to children’s learning of curse words?

7. How do children learn grammar without formal instruction?

8. What are the differences between child-centered and teacher- directed instruction?

9. Why is there disagreement about the extent to which Head Start benefits children?

10.Why do some cities and nations provide much better pre- school education than others?

1. Piaget is often criticized for his description of early cognition. Why is this, and is the criticism fair? (Discuss with particular ref- erence to preoperational thought.)

2. Give an example of the process of cognition in early childhood as Vygotsky would describe it, highlighting at least three of his specific concepts.

3. What are the main similarities between Vygotsky and Piaget?

4. How would parents act differently toward their child accord- ing to whether they agreed with Piaget or with Vygotsky?

5. How does Piaget’s idea of egocentrism relate to the research on theory of mind?

3. Theory of mind emerges at about age 4, but many adults still have trouble understanding other people’s thoughts and motives. Ask several people why someone in the news did whatever they did (e.g., a scandal, a crime, a heroic act). Then ask your inform- ants how sure they are of their explanation. Compare and analyze the reasons as well as the degrees of certainty. (One person may be sure of an explanation that someone else thinks is impossible.)

4. Think about an experience in which you learned something that was initially difficult. To what extent do Vygotsky’s concepts (guidance, language mediation, apprenticeship, zone of proximal development) explain the experience? Write a detailed, step-by- step description of your learning process as Vygotsky would describe it.

The best way to understand thinking in early childhood is to listen to a child, as applications 1 and 2 require. If some students have no access to children, they should do application 3 or 4.

1. Replicate one of Piaget’s conservation experiments. The easi- est one is conservation of liquids (pictured in Figure 9.1). Find a child under age 5, and make sure the child tells you that two identically shaped glasses contain the same amount of liquid. Then carefully pour one glass of liquid into a narrower, taller glass. Ask the child which glass now contains more or if the glasses contain the same amount.

2. To demonstrate how rapidly language is learned, show a pre- school child several objects and label one with a nonsense word the child has never heard. (Toma is often used; so is wug.) Or choose a word the child does not know, such as wrench, spatula, or a coin from another nation. Test the child’s fast-mapping.

KEY QUESTIONS

APPLICATIONS

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10

255

CHAPTER OUTLINE

� Emotional Development

Initiative Versus Guilt Psychopathology Empathy and Antipathy

� Parents

Parenting Style ISSUES AND APPLICATIONS:

Planning Punishment The Challenge of Media

� Becoming Boys and Girls

Theories of Gender Differences IN PERSON: Berger and Freud Gender and Destiny

The Play Years: Psychosocial Development

Imagine that you have two children, a typical 2-year-old and a 6-year-old. What a contrast! If you take your 2-year-old to the playground,don’t become absorbed in conversation. Before you realize it, yourchild may be crying atop a high slide, tasting a sandbox cake, grabbing a toy, or, worse, nowhere to be seen. Meanwhile, as long as adults are nearby, your 6-year-old is probably safe, sliding and sharing, not swallowing sand or disappearing without permission.

This chapter describes that 2-to-6 transformation. Maturation and moti- vation are crucial; so are emotions and experiences. Psychosocial develop- ment is multifaceted, involving genes, gender, parents, peers, and culture, all readily apparent in this chapter.

Emotional Development Learning when and how to express emotions (made possible as the emotional hotspots of the brain become linked to the executive functions) is the pre- eminent psychosocial accomplishment between ages 2 and 6 (N. Eisenberg et al., 2004). Children who master this task, called emotional regulation, become more capable in every aspect of their lives (Denham et al., 2003; Matsumoto, 2004).

Emotions are regulated and controlled by 6-year-olds in ways unknown to exuberant, expressive, and often overwhelmed toddlers. Children learn to be friendly to new acquaintances but not too friendly, angry but not explosive, frightened by a clown but not terrified, able to distract themselves and limit their impulses if need be. (All these abilities emerge during the preschool period and continue to develop throughout life.) Now we explain some spe- cific aspects of emotional regulation.

Initiative Versus Guilt Initiative is saying something new, extending a skill, beginning a project. De- pending on the outcome (including the parents’ response), some initiatives make children feel guilty—a consequence that can make children afraid to try new activities again. Children internalize past experiences of pride or shame, thus affecting their self-esteem or feelings of guilt.

emotional regulation The ability to control when and how emotions are expressed. This is the most important psychosocial development to occur between the ages of 2 and 6, though it continues throughout life.

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More generally, positive enthusiasm, effort, and self-evaluation characterize ages 3 to 6, according to Erik Erikson’s psychosocial theory. During what he called his third developmental stage, initiative versus guilt, Erikson described self-esteem as emerging from the acquisition of skills and competencies described in the previous two chapters.

Self-esteem is the belief in one’s own ability, a personal estimate of success and worthiness. As self-esteem builds, children become more confident and inde- pendent. The autonomy of 2-year-olds, often expressed as stubborn reactions, becomes the initiative of 5-year-olds, often seen in their self-motivated activities. In the process, children form a self-concept, or understanding of themselves, which includes not only self-esteem but also facts such as gender and size.

Balancing one’s own wishes with the expectations embedded in the social context is not easy, especially if one’s only playmate has been a mother who never thwarted the child’s initiative. For example, one child (about age 3) was new to peers and to preschool:

She commanded another child, “Fall down. Go on, do what I say.” When the other child stayed stalwartly on his feet, she pushed him over and was clearly amazed when he jumped up and said, “No pushing!” and the teacher came over and reproved her.

[Leach, 1997, p. 474]

In this example, the more experienced child has a strong self-concept that he was ready to defend. The inexperienced girl was “reproved,” not punished. The teacher hoped she would internalize the rule so that she would feel guilt (not shame) if she broke it again. Most older children and adults, but fewer 4- or 5-year- olds, experience guilt when their initiative clashes with the rules and regulations they have learned (Lagattuta, 2005).

Pride Erikson recognized that typical 3- to 5-year-olds have immodest and quite positive self-concepts, holding themselves in high self-esteem. They believe that they are strong, smart, and good-looking—and thus that any goal is quite achievable. Whatever they are (self-concept) is also thought to be good (for instance, little boys are proud of being male).

In the play years, children are confident that their good qualities will endure but that any bad qualities (even biological traits such as poor eyesight) will disappear with time (Lockhart et al., 2002). As one group of researchers explained:

initiative versus guilt Erikson’s third psy- chosocial crisis. Children begin new activities and feel guilty when they fail.

self-esteem How a person evaluates his or her own worth, either in specifics (e.g., intelligence, attractiveness) or overall.

self-concept A person’s understanding of who he or she is. Self-concept includes appearance, personality, and various traits.

256 CHAPTER 10 ■ The Play Years: Psychosocial Development

Close Connection Unfamiliar events often bring developmental tendencies to the sur- face, as with the curious boy and his worried brother, who are attending Colorado’s Pikes Peak or Bust Rodeo breakfast. Their attentive mother keeps the livelier boy calm and reas- sures the shy one.

Observation Quiz (see answer, page 259): Mother is obviously a secure base for both boys, who share the same family and half the same genes but are different ages: One is 2 and the other is 4. Can you tell which boy is younger? SEA

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Young children seem to be irrepressibly optimistic about themselves. . . . Consider, for example, the shortest, most uncoordinated boy in a kindergarten class who proclaims that he will be the next Michael Jordan.

[Lockhart et al., 2002, pp. 1408–1409]

The new initiative that Erikson describes is aided by a longer attention span (made possible by neurological maturity); now children have a purpose for what they do. Concentrated attention is believed to be crucial for later competence of all kinds, but concentration is not an automatic result of brain growth.

Self-esteem and concentration are connected to motivation, cognition, and experience, all of which correlate with matura- tion but are not caused by it. For example, 6-year-olds who have been chronically mistreated feel inadequate and incompetent, with abnormally low self-esteem (Kim & Cicchetti, 2006).

Feeling proud of oneself is the foundation for practice and then mastery, as children learn to pour juice or climb a tree. For most children, self-criticism does not arise until later. Preschoolers predict that they can solve impossible puzzles, re- member long lists of words, change every undesirable trait, and control the dreams that come when they are asleep (Stipek et al., 1995; Woolley & Boerger, 2002). Such naive predictions, sometimes called “protective optimism,” help them learn (Lockhart et al., 2002) because they are not afraid to try new things.

Guilt and Shame Notice that Erikson called the negative consequence of this crisis “guilt,” not shame. Erikson believed that because children develop self-awareness, they feel guilty when they realize their own mistakes. Generally, guilt means that people blame themselves because they have done something wrong, while shame means that people feel that others are blaming them.

Shame can be based on what is, such as one’s ethnic background. In this case, the shame is rooted in the belief that others devalue those of certain ethnicities or minorities. To counter such feelings of shame, many parents of minority children (Mexican, African, or Indian American, among others) wisely make sure their chil- dren feel proud of their identity (Parke & Buriel, 2006).

Guilt and shame often occur together, though they do not necessarily go hand in hand. For example, children who misbehave may shame the parents, but the parents do not usually feel guilty. Or a person could feel guilty (of driving too fast, for instance) but not ashamed.

Many thoughtful people believe that guilt is a more mature emotion than shame because guilt is internalized (Bybee, 1998; Tangney, 2001; Zahn-Waxler, 2000). Guilt originates within; it may bother a person even if no one else knows about the misdeed. Shame depends on other people; it comes from knowing that someone else might see and criticize what a person has done. Thus, Erikson’s expectation of shame at age 2 and guilt by age 5 signifies emotional maturation during these years.

Intrinsic Motivation The idea that guilt comes from within highlights the distinction between intrinsic motivation and extrinsic motivation. Intrinsic motivation is evident when a per- son does something for the joy of doing it—such as a musician who plays simply for the delight of making music, even if no one else is around to hear it. Extrinsic motivation comes from outside (ex-), when the reason to do something is to gain praise or some other reward from someone else.

intrinsic motivation Goals or drives that come from inside a person, such as the need to feel smart or competent.

extrinsic motivation The need for rewards from outside, such as material possessions or someone else’s esteem.

Emotional Development 257

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Happy and Colorful No wonder this 5-year- old is proud—her picture is worth framing. High self-esteem is one of the strengths of being her age. Can you imagine a 9-year-old holding an equally colorful picture so proudly?

Especially for College Students Is extrinsic or intrinsic motivation more influential in your study efforts?

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For the most part, preschool children are intrinsically motivated. They enjoy learning, playing, and practicing for their own joy, not be- cause someone else sets a goal for them. For instance, when they play games, young children might not keep score; the fun is in playing more than in winning.

In a classic experiment, preschool children were given Magic Mark- ers with which to draw and then placed into one of three groups with different conditions: (1) no award, (2) expected award (told before they had drawn anything that they would get a certificate), and (3) unex- pected award (they heard “You were a big help” and received a certifi- cate after they had drawn something) (Lepper et al., 1973). When the children returned to their classrooms, observers noted how often they chose to draw. Those who got the expected award drew less than those with the unexpected award. This was interpreted to mean that the extrinsic award undercut intrinsic motivation.

This research triggered a flood of studies. Researchers tried to un- cover whether, when, and how rewards should be given. The consensus is that praising or paying a person after work has been done encourages that behavior, as long as the reinforcement is based on actual accom- plishment. However, if substantial rewards are promised in advance for something that the person already enjoys doing, the extrinsic conse- quences may backfire by diminishing intrinsic motivation (Cameron & Pierce, 2002; Deci et al., 1999).

Cross-cultural research makes this more complex. Cultures differ re- garding which emotions need regulation and which internal and external motivations work best. For example, children are especially encouraged

to overcome their fears in the United States, to modify their anger in Puerto Rico, to temper their pride in China, and to control their aggression in Japan (Harwood et al., 1995; Hong et al., 2000; J. G. Miller, 2004). Emotional regulation is valuable everywhere, but cultures differ in the specifics (Matsumoto, 2004).

Psychopathology At every age, developmentalists are concerned with preventing or treating psy- chopathology, which is an illness or disorder (-pathology) that involves the mind (psycho-). The first signs of psychopathology in children usually involve emotions that seem to overwhelm the child. Emotional regulation begins with impulse con- trol. Often the impulse that most needs control is anger, because “dysregulated anger may trigger aggressive, oppositional behavior” (Gilliom et al., 2002, p. 222). Before such regulation, a frustrated 2-year-old might flail at another person or lie down screaming and kicking. A 5-year-old usually has more self-control, perhaps pouting and cursing, but not hitting and screaming.

Emotional Balance Without adequate control, emotions overpower children. This occurs in two, seemingly opposite, ways. Some children have externalizing problems: They lash out in impulsive anger, attacking other people or things. They are sometimes called “undercontrolled.”

Other children have internalizing problems: They are fearful and withdrawn, turning emotional distress inward. They are sometimes called “overcontrolled.” Both externalizing and internalizing children are unable to regulate their emotions properly or, more precisely, unable to regulate the expression of their emotions. They do not exercise enough control or they control themselves too much (Caspi & Shiner, 2006; Hart et al., 2003).

externalizing problems Difficulty with emo- tional regulation that involves outwardly expressing emotions in uncontrolled ways, such as by lashing out in impulsive anger or attacking other people or things.

internalizing problems Difficulty with emo- tional regulation that involves turning one’s emotional distress inward, as by feeling excessively guilty, ashamed, or worthless.

258 CHAPTER 10 ■ The Play Years: Psychosocial Development

Emotional Regulation Older brothers are not famous for being loving caregivers. How- ever, in the Mayan culture, older children learn to regulate their jealousy and provide major care for younger siblings while their parents work.

Observation Quiz (see answer, page 260): What do you see that suggests that this boy is paying careful attention to his brother?

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Emotional regulation is in part neurological, a matter of brain functioning. Because a child’s ability to regulate emotions requires thinking before acting, deciding whether and how to display joy, anger, or fear, emotional regulation is the province of the prefrontal cortex, the executive area of the brain. As you remember from Chapter 8, the prefrontal cortex reacts to the limbic system (by acting or inhibiting action), including those parts of the brain (including the amygdala) where powerful emotions, especially fear and anxiety, form.

Normally, neurological advances in the prefrontal cortex occur at about age 4 or 5, when children become less likely to throw a temper tantrum, provoke a physical attack, or burst into giggles (Kagan & Hershkowitz, 2005). Throughout the period from age 2 to 6, violent outbursts, uncontrollable crying, and terrifying phobias diminish, and the capacity for self-control—such as not opening a wrapped gift immediately if asked to wait—becomes more evident (Carlson, 2003; Grolnick et al., 2006).

Emotional differences between younger and older children begin within the brain, perhaps going beyond simple maturation to differences more closely linked to the XX or XY chromosomes (Colder et al., 2002). Although girls are better at regulating their externalizing emotions, they are less successful with internalizing ones. By adolescence, undercontrolled boys may be delinquents; overcontrolled girls may be anxious or depressed (Pennington, 2002).

Differences in Early Care Neurological damage can occur during early development, either pre- natally (if a pregnant woman is stressed, ill, or a heavy drug user) or in infancy (if an infant is chronically malnourished, injured, or frightened). Extensive stress can kill some neurons and stop others from developing properly (Sanchez et al., 2001). This may affect the child’s ability to reg- ulate his or her emotions—the temper tantrum of a particular 5-year-old may not be as readily controllable as for most kindergarten children.

Early care prevents or worsens innate problems with emotional control. Highly stressed infant rats develop abnormal brain structures. However, if stressed rat pups are raised by nurturing mothers, their brains are protected by hormones elicited by their mothers, who lick, nuzzle, groom, and feed them often (J. Kaufman & Charney, 2001). Similarly in humans, nurturing caregivers guide reactive children toward emotional regulation, helping them become more competent than many other children (Hane & Fox, 2006; Quas et al., 2004).

The harm of poor caregiving is evident in maltreated 4- to 6-year-olds. Most such children (80 percent in one study) are “emotionally disregulated,” either indifferent or extremely angry when strangers criticize their mothers (Maughan & Cicchetti, 2002). If neglect or abuse occurs in the first few years, it is more likely to cause internalizing or externalizing problems than mistreatment that begins when the child is older, probably because it harms the developing brain (Lopez et al., 2004; Manly et al., 2001).

Always remember that many influences affect each child. Nurture and nature interact, influencing the brain as well as behavior, through “multiple converging pathways,” many originating in the brain but also activated by experiences (Cicchetti & Walker, 2001, p. 414).

Empathy and Antipathy With increasing social awareness and decreasing egocentrism (as reviewed in Chap- ter 9), two other emotions develop: empathy, an understanding of the feelings and concerns of others, and antipathy, a dislike or even hatred of other people.

➤Response for College Students (from page 257): Both are important. Extrinsic motivation includes parental pressure and the need to get a good job after graduation. Intrinsic motivation includes the joy of learning, especially if you can express that learning in ways others recognize. Have you ever taken a course that was not required and was said to be difficult? That was intrinsic motivation—a sign that you will benefit from your college studies.

empathy The ability to understand the emo- tions of another person, especially when those emotions differ from one’s own.

antipathy Feelings of anger, distrust, dislike, or even hatred toward another person.

Emotional Development 259

Who’s Chicken? Genes and good parenting have made this boy neither too fearful nor too bold. Appropriate caution is probably the best approach to meeting a chicken.

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➤Answer to Observation Quiz (from page 256): Size is not much help, since children grow slowly during these years and the heads of these two boys appear about the same size. However, emotional development is apparent. Most 2-year-olds, like the one at the right, still cling to their mothers; most 4-year- olds are sufficiently mature, secure, and curious to watch the excitement as they drink their juice.

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Empathy is not the same as sympathy, which is feeling sorry for someone. It is feeling sorry with someone, feeling their pain as if it were one’s own. Research with mirror neurons (see Chapter 1) suggests that observing someone else may activate the same areas of the brain as in the person directly involved. This is how empathy works. Antipathy likewise is a personal and emotional reaction, much stronger than merely disagreeing with someone.

Preschoolers develop empathy, but as you may remember from the Chapter 9 discussion of egocentrism and theory of mind, they do not always read others’ emotions accurately (Saarni et al., 2006). For instance, when a person says in a very sad voice, “I came in first place in a race,” virtually every 6-year-old judges the person to be unhappy, but almost no child younger than 6 recognizes the impor- tance of tone (Morton et al., 2003). In other words, it takes maturity to correctly read tone, expression, and body language when they contradict what the child would feel in that situation.

Young children (ages 3 and 4) also confuse another person’s intentions and desires, a mistake that older children and adults rarely make (Leslie et al., 2006; Schult, 2002). Finally, young children can experience too much empathy, becom- ing so distressed by someone else’s problem that they are not able to help (Saarni et al., 2006). An overly empathetic 3-year-old whose friend bumped his head may be overwhelmed with sadness and unable to find ice, tell an adult, or even express words of comfort.

Leading to Behavior Ideally, empathy leads to prosocial behavior, being helpful and kind without gaining any obvious benefit. Expressing concern, offering to share food or a toy, and including a shy child in a game or conversation are examples of prosocial behavior.

Antipathy can lead to antisocial behavior, deliberately injuring someone or destroying something that belongs to another (Caprara et al., 2001). Antisocial actions include verbal insults, social exclusion, and physical assaults. An antisocial 4-year-old might look another child in the eye, scowl, and then kick him hard without provocation.

By age 4 or 5—as a result of brain maturation, theory of mind, emotional regu- lation, and interactions with caregivers—most children can be deliberately proso- cial or antisocial, with prosocial behavior generally increasing from age 3 to 6 and beyond (N. Eisenberg et al., 2006). Imagine that a boy hits his mother. If he is a toddler, the mother usually realizes that he is experimenting, a tertiary circular

reaction, and she should stop him with a stern expression but not feel personally attacked.

However, if her son is 5, something is seriously wrong. In fact, according to a study in Montreal, when 5-year-olds are mean to their mothers (phys- ically or verbally), that signifies a disturbed rela- tionship, and the child is headed for externalizing problems with others at school, with friends, and probably later in life (Moss et al., 2004).

Cultures vary in how much they allow, punish, or encourage both prosocial and antisocial behav- ior, as well as in what particular behaviors are con- sidered good and bad. In one specific example (see Figure 10.1), when Japanese and U.S. mothers were helping their 4-year-olds with a puzzle, the Japanese mothers were likely to emphasize mutu- ality (e.g., “This puzzle is hard for us”), while the

He’s Listening With tilted head and pink tutu, this girl exemplifies two of the best characteristics often found in young children: empathy and self-confidence. Responding to her personality and concern, the distressed boy may well decide to rejoin the group.

prosocial behavior Feeling and acting in ways that are helpful and kind, without obvious benefit to oneself.

antisocial behavior Feeling and acting in ways that are deliberately hurtful or destructive to another person.

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Especially for Adults Who Are Unhappy What would prompt a young child to cheer someone up?

➤Answer to Observation Quiz (from page 258): Look at his hands, legs, and face. He is holding the bottle and touching the baby’s forehead with delicacy and care; he is positioning his legs in a way that is uncomfortable but suited to the task; and his eyes and mouth suggest he is giving the baby his full concentration.

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instrumental aggression Hurtful behavior that is intended to get or keep something that another person has.

reactive aggression An impulsive retaliation for another person’s intentional or acciden- tal actions, verbal or physical.

bullying aggression Unprovoked, repeated physical or verbal attack, especially on victims who are unlikely to defend them- selves.

Emotional Development 261

U.S. mothers tended to emphasize individuality (e.g., “You are having a hard time with this puzzle”) (Dennis et al., 2002; see Research Design). If this is typical, then Japanese children might learn to empathize more than U.S. children would.

Preschool children are capable of feeling empathy for others of their own group (national, ethnic, religious, or familial) without feeling antipathy toward people of other groups, never realizing that their values and goals are not universally shared (Verkuyten, 2004). In fact, their innocence can be astonishing, as researchers found in Northern Ireland: Most 6-year-olds said they did not know of any prob- lems between the Catholics and Protestants (Sani & Bennett, 2004). Meanwhile, many adults in their communities felt such antipathy that even killing was possible.

Most young children are not prejudiced against other children because of back- ground characteristics such as gender or ethnicity. A 5-year-old girl might say “I hate boys” because her older sister says that, but she may consider a boy her best friend. Typically, best friends are of the same sex and background, but that is because of personal interests more than categories (Rubin et al., 2006). When children are prejudiced (and some are), that usually begins when they are older, influenced by family and culture (Nesdale, 2004; Ruble et al., 2004). More often, young children feel empathy toward any child who is hurt, hungry, or otherwise in trouble.

Aggression The gradual regulation of emotions and emergence of antipathy is nowhere more apparent than in the most antisocial behavior of all, active aggression, which occurs when a child’s dislike erupts into action. Learning when and how to be aggressive is a major goal of the play of young children. This is evident on close observation of rough-and-tumble play; or in the fantasies of domination and submission that shine through sociodramatic play; or in the sharing of art supplies, construction materials, and wheeled vehicles (J. D. Peterson & Flanders, 2005). Children learn to inhibit their angry impulses in emotional regulation.

Researchers recognize many types of aggression, described in Table 10.1. Instrumental aggression is very common among young children, who often want something they do not have and will try, without thinking, to get it. Reactive aggression is impulsive as well, and this type, particularly, becomes better con- trolled with emotional regulation. Finally, bullying aggression is the most omi- nous, when a child seems to deliberately hurt another.

Research Design Scientists:Tracy A. Dennis, Pamela Cole, Carolyn Zahn-Waxler, and Ixchiro Mizuta.

Publication: Child Development (2002).

Participants: Sixty 4-year-olds in two groups of 30, one in Japan and one in the United States.

Design: Mothers played with their chil- dren while their interaction was video- taped. Later, coders who were blind to the hypothesis coded the mother’s and the child’s actions and speech in more than 20 categories. One was individual- ity and one was autonomy.Validity and reliability checks on the coding helped ensure standardization.

Major conclusion: Many similarities and a few differences (some opposite to the stereotypes) were found. Japanese mothers emphasized mutuality much more, and U.S. mothers emphasized in- dividuality.

Comment:The two groups were closely matched on many factors, including child’s age, parents’ age, and education. This suggests that the differences were primarily cultural. Replication, with 4- year-olds in these and other nations, is needed.

Source: Dennis et al., 2002.

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How Empathy Is Taught During free play with their 4-year-olds, Japanese mothers were more likely than U.S. mothers to emphasize mutuality, or inter- dependence. U.S. mothers tended to stress individuality, or self-reliance. This study demonstrates the role of culture in children’s development of empathy.

Especially for Young Adults When you were younger, you might have had an imaginary friend with whom you played, slept, and talked. Does this mean you were emotionally disturbed?

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Bullying is not always physical; it can be verbal or relational when the goal is to disrupt a child’s friendships. Physical aggression declines over the preschool and school-age years, but verbal attacks may increase (Dodge et al. 2006). So might relational aggression (described in Chapter 13).

Bullying is apparent among some young children, with boys particularly likely to use physical attacks. Preschool bullies must be stopped, and victims must learn to defend themselves, lest the bully/victim patterns continue throughout middle childhood and adolescence. The various forms of bullying and the consequences are described in detail in Chapter 13, on school-age children.

Aggression follows a developmental pattern, becoming less common, but more hurtful, with time. Infants are very aggressive; they naturally pinch, slap, and even bite others. In Richard Tremblay’s dramatic words, “The only reason babies do not kill each other is that we do not give them knives or guns” (quoted in Holden,

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TABLE 10.1

The Four Forms of Aggression

Type of Aggression Definition Comments Hurtful behavior that is aimed at gaining something (such as a toy, a place in line, or a turn on the swing) that someone else has

An impulsive retaliation for a hurt (intentional or accidental) that can be verbal or physical

Nonphysical acts, such as insults or social rejection, aimed at harming the social connections between the victim and others

Unprovoked, repeated physical or verbal attack, especially on victims who are unlikely to defend themselves

Instrumental aggression

Reactive aggression

Relational aggression

Bullying aggression

Often increases from age 2 to 6; involves objects more than people; quite normal; more egocentric than antisocial.

Indicates a lack of emotional regulation, characteristic of 2-year-olds. A 5-year-old should be able to stop and think before reacting.

Involves a personal attack and thus is directly antisocial; can be very hurtful; more common as children become socially aware.

In both bullies and victims, a sign of poor emotional regulation; adults should intervene before the school years. (Bullying is discussed in Chapter 13.)

Ladies and Babies A developmental differ- ence is visible here between the 14-month- old’s evident curiosity and the 4-year-old friends’ pleasure in sociodramatic play. The mother’s reaction—joy at the children’s mastery play or irritation at the mess they’ve made—is less predictable. FEL

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➤Response for Young Adults (from page 261): No. In fact, imaginary friends are quite common, especially among creative children.

➤Response for Adults Who Are Unhappy (from page 260): Young children are not good at guessing emotions from voice tone, facial expression, or sarcasm. They are naturally sympathetic if an adult sheds a few tears while describing a sad event, thereby expressing feelings clearly and directly.

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2000, p. 580). Fortunately, babies are not strong and they have no weapons, giving parents time to teach them some self-control before any serious harm occurs.

Almost all 2-year-olds are still somewhat aggressive, but the incidence of such behavior diminishes over the next two years. If a child has not begun to modify his or her antisocial behavior by age 3 or 4, that child may be violent throughout child- hood, adolescence, and early adulthood (Loeber et al, 2005; Tremblay & Nagin, 2005). However, if parents have a good relationship with their child and they help him or her decrease aggression, then the child will probably do well, academically and socially, displaying only average aggression by middle childhood (NICHD Early Child Care Research Network, 2004).

Remember that emotions need regulation, not repression. Since overcontrol, not just undercontrol, can lead to psychological problems, some assertive and self-protective behaviors are probably beneficial (Hawley, 1999). An internalizing 4-year-old who cries and retreats from every threat may become a victim, overwhelmed by anxiety or depression later on. Thus, some aggression in early childhood is quite normal (NICHD Early Child Care Network, 2004).

As self-esteem and the self-concept build, children become more likely to defend their interests. As emotional regulation increases, they do not attack without reason. Normal 4-year-olds have learned to choose issues and targets as well as to control the type and intensity of aggression (Tremblay & Nagin, 2005).

SUMMING UP

As Erikson describes, pride, purpose, and initiative are integral components in the self- concept of young children. Preschoolers typically have high self-esteem. Children who have difficulty with emotional regulation often develop internalizing or externalizing problems. Many researchers believe that emotional regulation is the foundation for later social skills and cognitive growth, as children become more prosocial and less antisocial, expressing empathy more than anger. Some aggression is normal in young children, who gradually learn to regulate their anger.

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Emotional Development 263

Male Bonding Sometimes the only way to distinguish aggression from rough-and-tumble play is to look at the faces. The hitter is not scowling, the hittee is laughing, and the hug- ger is just joining in the fun. Another clue that this is rough-and-tumble play comes from gender and context. These boys are in a Head Start program, where they are learning social skills, such as how to avoid fighting.LAU

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A Real Fight? Could be. We cannot see the boys’ faces, and we do not know what led up to this moment.

Observation Quiz (see answer, page 264): Are any signs of a serious fight visible?

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Parents We have seen that young children’s emotions and actions are affected by many factors, including brain maturation and culture. Now we focus on another primary influence: parents.

Parenting Style Parents differ a great deal in what they believe about children and how they act with them. Although thousands of researchers have traced the effects of parenting on child development, the work of one person, 40 years ago, continues to be most influential. Diana Baumrind (1967, 1971) studied 100 preschool children, all from California, almost all middle-class European Americans. (The cohort and cultural limitations of this sample were not obvious at the time.)

Baumrind found that parents differed on four important dimensions:

■ Expressions of warmth. Some parents are very affectionate, others cold and critical.

■ Strategies for discipline. Parents vary in whether and how they explain, criticize, persuade, ignore, and punish.

■ Communication. Some parents listen patiently; others demand silence. ■ Expectations for maturity. Parents vary in standards for responsibility and self-

control.

Baumrind’s Three Patterns of Parenting On the basis of these dimensions, Baumrind identified three parenting styles (see Table 10.2).

■ Authoritarian parenting. The parents’ word is law, not to be questioned. Misconduct brings strict punishment, usually physical (but not so harsh as to be considered abusive). Authoritarian parents set down clear rules and hold high standards. They do not expect children to give their opinions; discussion about emotions is especially rare. (One adult from such a family said that the question “How do you feel?” had only two possible answers: “Fine” and “Tired.”) Authoritarian parents love their children, but they seem aloof, rarely showing affection.

■ Permissive parenting. Permissive parents make few demands, hiding any impatience they feel. Discipline is lax partly because permissive parents have low expectations for maturity. Instead, permissive parents are nurturing and accepting, listening to whatever their offspring say. They want to be helpful, but they do not feel responsible for shaping their children.

■ Authoritative parenting. Authoritative parents set limits and enforce rules, but they also listen to their children. The parents demand maturity, but they are usually forgiving (not punishing) if the child falls short. They consider themselves guides, not authorities (as authoritarian parents do) or friends (as permissive parents do).

As explained in Chapter 8, no researcher has ever found that abusive or neg- lectful parenting helps children. This means that authoritarian parents must take care not to punish too often or too harshly and that permissive parents must be concerned about, not indifferent to, their children’s well-being.

Many other researchers continue to study parenting styles. The three-part de- scription above, although still influential, is too simple (e.g., Bornstein, 2006; Galambos et al., 2003; Lamb & Lewis, 2005; Parke & Buriel, 2006). Baumrind’s original sample was limited (very little economic, ethnic, or cultural diversity):

authoritarian parenting Child rearing with high behavioral standards, punishment of misconduct, and low communication.

264 CHAPTER 10 ■ The Play Years: Psychosocial Development

permissive parenting Child rearing with high nurturance and communication but rare punishment, guidance, or control.

authoritative parenting Child rearing in which the parents set limits but listen to the child and are flexible.

➤Answer to Observation Quiz (from page 263): No. Boys acting out of antipathy kick and pummel, grab and pull, bite and pound. None of that is shown here.

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She focused on style more than daily processes; she did not take into account the child’s substantial contribution to parent–child relationships; and she did not realize that some authoritarian parents are very loving and that some permissive parents guide their children with words, if not with rules.

Children growing up with these three styles have been followed longitudinally, and the following correlations have been reported (Baumrind, 1991; Steinberg et al., 1994):

■ Authoritarian parents raise children who are likely to be conscientious, obedient, and quiet but not especially happy. The children tend to feel guilty or depressed, internalizing their frustrations and blaming themselves when things don’t go well. As adolescents, they sometimes rebel, leaving home before age 20.

■ Permissive parents raise unhappy children who lack self-control, especially in the give-and-take of peer relationships. Inadequate emotional regulation makes them immature and impedes friendships, which is the main reason for their unhappiness. They tend to live at home, still dependent, in early adulthood.

■ Authoritative parents raise children who are successful, articulate, happy with themselves, and generous with others. These children are usually liked by teachers and peers, especially in cultures where individual initiative is valued.

An especially important factor regarding parenting style during the preschool years is a child’s temperament. Fearful children and impulsive children need different parental responses (Kochanska et al., 2001; Van Leeuwen et al., 2004). This means that any simple formula of the best parenting is likely to be wrong in some cases; a child’s personality and the social context are always significant.

Cultural Variations Effective Chinese American, Caribbean American, and African American parents are often stricter than effective parents of northern or western European back- grounds (Chao, 2001; Wachs, 1999). It is important to acknowledge that multi- cultural and international research has found that specific discipline methods and family rules are less important than parental warmth, support, and concern (McLoyd & Smith, 2002; Parke & Buriel, 2006). Children from every ethnic group and every country benefit if they believe that their parents appreciate them; children everywhere suffer if they feel rejected and unwanted (Khaleque & Rohner, 2002; Maccoby, 2000).

An example of the role of culture in discipline comes from the contrast between mothers in Japan and in the United States. Japanese mothers tend to use reason- ing, empathy, and expressions of disappointment to control their children more than North American mothers do. These techniques work well, partly because the

Especially for Political Activists Many observers contend that children learn their political attitudes at home, from the way their parents treat them. Is this true?

Parents 265

TABLE 10.2

Characteristics of Parenting Styles Identified by Baumrind

Characteristics

Communication

Style Warmth Discipline Expectations of Maturity Parent to Child Child to Parent

Authoritarian Low Strict, often physical High High Low

Permissive High Rare Low Low High

Authoritative High Moderate, with much discussion Moderate High High

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Japanese mother–child relationship is strongly affectionate (it is called amae, a close interpersonal bond) (Rothbaum et al., 2000).

Would North American parents successfully raise their children if they expressed more sympathy and less anger with their misbehaving 4-year-olds? There is no simple answer. But cross-cultural differences in disciplining young children are apparent (e.g., physical punishment is illegal in some Scandinavian nations, common in some Latin American ones).

Dozens of other differences in values, climate, economy, history, and so on are evident between nations (and among groups within nations). Each of these factors could affect child-rearing practices. It is impossible to draw simple conclusions about discipline and adult personality, because definitive research linking cross-cultural variables has not been done (Matsumoto & Yoo, 2006).

Given this appreciation that cultural differences reflect a group’s adapta- tion to its specific setting, developmentalists hesitate to recommend any one particular style of parenting as best for everyone (Dishion & Bullock, 2002; J. G. Miller, 2004). That does not mean that they believe all parents function equally well—far from it. Signs of serious trouble are obvious in a child’s behavior, including several mentioned in this chapter: overcontrol, undercontrol, bullying, and antisocial play. Ineffective parenting is not the only explanation for such problems, but it is one common cause. Solutions, however, vary.

Discipline and Punishment A particular issue for many developmentalists and parents is discipline,

which varies a great deal from family to family, culture to culture. Given what re- searchers have learned about cognition (that children do not understand complex causes), ideally parents anticipate misbehavior and guide their children toward patterns that will help them lifelong. But parents cannot always anticipate and prevent problems; punishment is sometimes necessary.

No disciplinary technique works quickly and automatically to teach any and all children desired behavior. It is easy to stop a child for a moment, with a threat or a slap, but it is hard to shape behavior so that the child gradually internalizes the parents’ standards. Yet this is the goal and sometimes the result. Between ages 2 and 6, children learn to reflect on consequences, to control their emotions,

and to bring their actions closer to what their parents expect. The child becomes self-regulating, not just obedient.

In every nation and family, the first step is clarity about what is expected. What is “rude” or “nasty” or “undisciplined” behavior in one community is often accepted, even encouraged, in another. Each family needs to decide its goals and make them explicit for the child. Parents have a wide range of expecta- tions and thoughts regarding child rearing, although they are often unaware of them (Bornstein, 2006; Bugental & Grusec, 2006). This diversity is all the more reason both parents need to discuss their expectations—to form a strong parental alliance.

The second step is to remember what the child is able to do. Many parents forget how immature chil- dren’s control over their bodies and minds is. For instance, some parents punish children for wetting

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Parenting Style This woman is disciplining her son, who does not look happy about it.

Observation Quiz (see answer, page 270): Which parenting style is shown here?

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Pay Attention Children develop best with lots of love and attention. They shouldn’t have to ask for it!

“He’s just doing that to get attention.”

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the bed, but no child deliberately wets the bed. Three-year-olds are clumsy and irrational; they inevitably break things and tell “lies.”

Punishment should be rare, reserved for misdeeds that the child understands and could reasonably control. Other developmental characteristics to remember are listed in Table 10.3, and different methods of punishment are discussed in the following.

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Planning Punishment

Physical punishment (slapping, spanking, or beating) is used more on children between the ages of 2 and 6 than on children of any other age group. Many parents believe that spanking is acceptable, legitimate, and sometimes necessary, and they often remember being spanked themselves.

However, the life-span perspective reminds us of long-term consequences. Physical punishment works at the moment it is administered—spanking stops a child’s misbehavior—but longi- tudinal research finds that children who are physically punished are likely to become bullies, delinquents, and then abusive adults. Domestic violence of every type—spousal abuse, threats, and insults—correlates with antisocial behavior in childhood and then adulthood (Jaffee et al., 2004; Straus, 1994). Of course, many children who are spanked do not become violent adults. Spanking increases the risk, but other factors (poverty and tem- perament, among others) are stronger influences. Nonetheless, developmentalists wonder why parents would increase any risk. Since physical punishment increases the possibility of aggression and only temporarily increases obedience, it is not recommended (Amato & Fowler, 2002; Gershoff, 2002).

In truth, every form of punishment may have unintended consequences. Another method, psychological control, uses

guilt and the child’s gratitude toward the parent and may dam- age a child’s initiative and achievement (Barber, 2002).

Consider the results of a study of an entire cohort (the best way to obtain an unbiased sample) of children born in Finland (Aunola & Nurmi, 2004). Their parents were asked 20 ques- tions about their approach to child rearing. The following four items, which the parents rated from 1 (“Not at all like me”) to 5 (“Very much like me”), measured psychological control:

1. My child should be aware of how much I have done for him/her.

2. I let my child see how disappointed and shamed I am if he/she misbehaves.

3. My child should be aware of how much I sacrifice for him/her. 4. I expect my child to be grateful and appreciate all the advan-

tages he/she has.

The higher the parents scored on psychological control, the lower the children’s math scores. The connection grew stronger as the children advanced in school. Math achievement suffered most if parents were high in both psychological control and affection (e.g., they frequently hugged their children) (Aunola & Nurmi, 2004). Other research also finds that psychological

issues and applications

TABLE 10.3

Relating Discipline to Developmental Characteristics During Early Childhood

1. Remember theory of mind. Young children gradually come to understand things from other viewpoints. Encouraging empathy (“How would you feel if someone did that to you?”) increases prosocial and decreases antisocial behavior.

2. Remember emerging self-concept. Young children are developing a sense of who they are and what they want. Adults should protect that emerging self, neither forcing 3-year-olds to share their favorite toys nor saying, “Words do not hurt.” Instead, children need to know when and how to protect their favorite possessions and their emerging sense of self. For instance, a child can learn not to bring a toy to school unless he or she is willing to share it with everyone.

3. Remember the language explosion and fast-mapping. Young children are eager to talk and think, but they say more than they really understand. Children who “just don’t listen” should not always be punished, because they may not have understood a command. Discussion before and after they misbehave helps children learn.

4. Remember that young children are not yet logical. The connection between misdeed and punishment needs to be immediate and transparent, but usually it is not. If you were spanked as a child, do you remember why? Did you ever do the same misdeed again?

psychological control A disciplinary tech- nique that involves threatening to withdraw love and support and that relies on a child’s feelings of guilt and gratitude to the parents.

➤Response for Political Activists (from page 265): There are many parenting styles, and it is difficult to determine each one’s impact on children’s personalities. At this point, attempts to connect early child rearing with later political outlook are speculative at best.

Especially for Parents Suppose you agree that spanking is destructive, but you some- times get so angry at your child’s behavior that you hit him or her. Is your reaction appropriate?

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The Challenge of Media Some people (not parents) imagine that parenting is straightforward and that good parents always have good children. Not so. Children are emotionally immature,

sometimes angry or fearful or defiant. Preschoolers, in particular, talk when they should be quiet, run when they should walk, show off when they should be modest.

Further, each cohort of parents is faced with challenges that their parents never confronted. Currently, those challenges include new junk food; far more single-parent families than in the past (about 40 percent, discussed in the following chapters); earlier sexual awareness; and an explosion of media, including the Internet (Comstock & Scharrer, 2006).

Parents allow their young children to watch television or use the computer not only because the children demand it but also because video keeps children engaged. Parents easily ignore the possible impact on the emotionally immature child, who is dazzled by fast-moving images and entranced by cartoon figures that have no empathy. Almost no preschooler understands “the motivated purpose of a commercial as a self-interested vehicle intended to benefit the advertiser” (Comstock & Scharrer, 2006, p. 833).

268 CHAPTER 10 ■ The Play Years: Psychosocial Development

control can depress children’s achievement and social accept- ance, although affection does not always make things worse (Barber, 2002).

One disciplinary technique often used in North America is the time-out, in which an adult requires the child to sit quietly apart from other people for a few minutes. For young children, a time-out can be quickly effective; one minute of time-out per year of age is suggested. Another common practice is withdrawal of love, when the parent expresses disappointment or looks sternly at the child, as if the child were no longer lovable.

A third method is induction, in which the parents talk with the child, getting the child to under- stand why the behavior was wrong. Conversation helps children internalize standards, but listening takes time and patience from the child as well as from the adult. Since 3-year-olds do not un- derstand causes and consequences, they cannot answer an angry “Why did you do that?”

Each method varies in consequences and effectiveness, depending on the child’s temperament, the culture, the parents’ personalities, and the parent– child relationship. For example, a time- out is effective if the child prefers to be with other people. One version of time- out for older children is suspension from school, which works if the child wants to be in the classroom. However, if a child

dislikes school, time-out becomes a reinforcement for the child (and the teacher), making future disobedience more likely.

There is no simple answer partly because children’s personal- ities and parental pressures vary. As a mother, I know that pa- tient guidance is necessary and that prevention is better than punishment, but emotions can be overwhelming. Rachel, at age 3, took a glass orange juice bottle from the refrigerator, dropping it on the kitchen floor. It shattered. I wanted to slap her. “Time- out!” I yelled, putting her on the couch (20 feet away) until I cleaned it up. I needed that time-out more than she did.

Parents have powerful emotions, memories, and stresses. That’s why punishment is not a simple issue. One young child who was disci- plined for fighting protested, “Some- times the fight just crawls out of me.” Ideally, punishment won’t just crawl out of the parent.

Angela at Play Research suggests that being spanked is a salient and memorable experience for young children, not because of the pain but because of the emotions. Children seek to do what they have learned; they know not only how to place their hands but also that an angry person does the hitting. The only part of the lesson they usually forget is what particular misdeed precipitated the punishment. Asked why she is spanking her doll, Angela will likely explain, “She was bad.”DA

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time-out A disciplinary technique in which a child is separated from other people for a specified time.

“Why don’t you get off the computer and watch some TV?”

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Experts advise parents to minimize media exposure, including no television before age 2. Six major organizations devoted to the health of children (the Ameri- can Psychological Association, the American Academy of Pediatrics, the American Medical Association, the American Academy of Child and Adolescent Psychiatry, the American Academy of Family Physicians, and the American Psychiatric Association) implore parents to stop exposing their children to video violence— whether in cartoons, in situation comedies, in video games, or on the evening news. This leaves almost nothing to watch (C. A. Anderson & Bushman, 2002).

Did you notice that all six organizations have American in their titles? That requires a cross-cultural advisement: Most of the research reported here studied U.S. children watching U.S. media (C. A. Anderson & Bushman, 2002; Roberts & Foehr, 2004). Readers need to ask themselves whether this limits the conclu- sions reported here or whether American media are so pervasive that the same problems exist worldwide.

The Importance of Content Most young children of every ethnic and economic group in the United States spend more than three hours each day using some sort of media (see Table 10.4). Among young children, television is the most popular medium. Almost every home has at least two televisions, and children usually watch apart from their parents, often in their own rooms. By age 3, more than one-fourth of all children already have a television in their bedrooms, and this percentage rises as children grow older (Roberts & Foehr, 2004).

What do children see? The “good guys,” whether in cartoons or police dramas, do as much hitting, shooting, and kicking as the “bad guys,” yet the consequences of their violence are sanitized, justified, or made comic. Almost all the good guys are male and White. Women are usually portrayed as victims or adoring girl- friends, not as leaders—except in a very few girl-oriented programs that boys rarely watch.

Attempts to restrict children’s watching have limited success. For instance, many TV programs and movies are now labeled regarding their appropriateness for children, but this is voluntary and many producers refuse to do it. Parents can install a V-chip in their television to limit what children can see, but few families have done so successfully. For many reasons, such voluntary measures have little effect on children’s exposure to violence and sex, especially for children who are most vulnerable.

Evidence from every perspective and method confirms that violence is pervasive and that children of all ages who watch violence on television become more violent themselves (C. A. Anderson et al., 2003; Huesmann et al., 2003; J. G. Johnson et al., 2002; Singer & Singer, 2005). For example, they are more likely to get into fights with each other and even to break things and hurt people when they grow up. For obvious reasons, extensive longitudinal research has not been published for the newer media, but virtually all developmentalists expect that sexual messages and aggression on all media (DVDs, MP3 players, the Internet) undermine opti- mal development of young children (Comstock & Scharrer, 2006).

Past research gives parents good reason to limit their children’s media involve- ment. Consider the results of a longitudinal study that began with children at about age 5 and queried those same children again as adolescents (D. R. Anderson et al., 2001; see Research Design).

Preschoolers who watched a lot of violence on television and copied the actions of cartoon characters were more violent and less creative. They had lower grades in school when they were older. This was true for both sexes and evident in every subject, but some correlations were particularly strong. For instance, 5-year-old

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TABLE 10.4

Average Daily Exposure to Electronic Media

Age 2 to 4 Years Hours per Day White 3:18

Black 4:30

Hispanic 3:37

Age 5 to 7 Years Hours per Day White 3:17

Black 4:16

Hispanic 3:38

Source: Adapted from Roberts & Foehr, 2004.

Research Design Scientists: Daniel Anderson, Aletha C. Huston, Kelly L. Schmitt, Deborah L. Linebarger, and John C. Wright.

Publication: Monographs of the Society for Research in Child Development (2001).

Participants: A total of 570 adolescents from Massachusetts and Kansas, whose television watching and other character- istics were studied in depth (viewing diaries recorded exactly what they watched).

Design:These participants and their television viewing were first studied at age 5. As adolescents, they were asked questions about their current lives, and their high school transcripts were obtained. Researchers controlled for many factors (e.g., SES, gender, region), seeking correlations between viewing habits at age 5 and behavior at age 16 or so. Efforts were made to understand causation, not just correlation.

Major conclusion: Sixty-five correlations were found between television viewing at preschool and adolescent behavior and characteristics. Most but not all effects were negative, leading to the con- clusion that content matters: “Marshall McLuhan appears to have been wrong. The medium is not the message.The message is the message” (p. 134).

Comment:These researchers wisely fol- lowed up on hundreds of preschoolers who had been carefully surveyed many years earlier.The result confirms the conclusions of many cross-sectional and shorter longitudinal studies:Television in the early years affects behavior in school.The other interesting result was not predicted by those most critical of TV:The content of some programs facili- tates learning.

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girls generally watched less violence than boys did, but when they did, the effects were greater.

There were also some positive effects of early television watching, depending on the programs watched. Young children who watched only educational programs (mostly Sesame Street and Mr. Rogers’ Neighborhood) became teenagers who earned higher grades and read more than other high school students did, especially if they were boys. This study also examined what the children watched as adolescents and again found an impact, almost always negative.

From a developmental perspective, early childhood is the best time to raise this issue because that is when household media habits are established. Young children are strongly influenced by their parents and older siblings, who often watch TV during meals or spend hours with television, computer, and hand-held video games. Already in 1999, one-fourth of all 6-year-olds had played a computer or video game within the past 24 hours (Roberts & Foehr, 2004). And the numbers are rising each year.

Early childhood is a vulnerable period for media effects for other reasons as well. First, young children spend more time in front of TV and computer screens than do people of any other age group. Second, young children are not very knowl- edgeable about society, culture, and people; they are novices at interpreting and regulating emotions. For example, when a cartoon animal or even a person ex- plodes on the screen, they are more likely to cheer than to cry.

The Effects on Family life Probably the worst effect of the media is how it interferes with family life. Chil- dren benefit when their parents are involved in their lives, as already apparent in the discussion of parenting patterns. As you have seen, language development (the crucial cognitive achievement of early childhood) depends on hours of one-on-one conversations every day. Likewise, emotional regulation (the crucial psychosocial accomplishment of early childhood) depends on parental responsiveness.

Unfortunately, all the research reports that the more media a family uses, the less time they spend together. Parents and children talk only briefly when they watch together, and they rarely watch together. In most families, parents and children have their own TVs, often in separate rooms. Further interfering with family time, the tele- vision often stays on during meals and even when no one is watching.

All told, the result is “parental abdication of oversight on chil- dren’s media behavior” (Roberts & Foehr, 2004, p. 202). Not only do the media cut into the time children spend with their parents, they also reduce the amount of time children spend in imagina- tive and social play—and thus on learning.

Although many adults hope that more time spent with one type of media would mean less time spent with another, this is not the case. The only exception is with print: Children who read many books tend to watch less TV (Roberts & Foehr, 2004). It is not surprising that grades suffer and impulsive violence increases as children watch more TV.

No wonder those six organizations recommend limited televi- sion. But few parents can enforce a total prohibition. (When you read about fast-mapping in Chapter 9, did you wonder why Sarah called me angry names? It was because I had momentarily un- plugged the TV.) Parents can, however, limit their own and their children’s media exposure and play, read, and talk with their chil-

Dangerous Toy? Would this 4-year-old at the computer be safer playing outside with a ball?

270 CHAPTER 10 ■ The Play Years: Psychosocial Development ©

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➤Answer to Observation Quiz (from page 266): The authoritative style. Note the firm hold this woman has on her defiant son; he must listen (evidence that she is not permissive). Also note that she is talking to him, not hitting or yelling, and that her expression is warm (evidence that she is not authoritarian).

“Have some respect for my learning style.”

Video Style Children who spend a lot of time watching television and playing video games are likely to develop a visual learning style. They get used to receiving information in the form of vivid images and brief scenes, making it harder for them to concentrate on and comprehend anything that is longer and presented in verbal form.

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dren more. Few children know a proven fact: An animated parent can be more en- tertaining than Mickey Mouse.

SUMMING UP

Over the past 40 years, Diana Baumrind and most other developmentalists have found that authoritative parenting (warm, with guidance) is more effective than either authori- tarian (very strict) or permissive (very lenient) parenting. In any culture, children thrive when their parents appreciate them and care about their accomplishments. The children of parents who are uninvolved, uncaring, or abusive are seldom happy, well-adjusted, and high-achieving.

Good parenting is not achieved by following any one simple rule; children’s tempera- ments vary, and so do cultural patterns. The media pose a particular challenge world- wide because children are attracted to colorful, fast-paced images, yet violent TV programs, in particular, lead to more aggressive behavior. Parental monitoring of the quality and quantity of the media—the underlying messages as well as the overt themes—to which children are exposed is recommended by every expert.

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Becoming Boys and Girls Identity as a male or female is an important feature of a child’s self-concept, a major source of self-esteem (with each gender believing that it is best) (Powlishta, 2004). The first question asked about a newborn is “Boy or girl?” and parents select gender-distinct clothes, blankets, diapers, and even pacifiers. Toddlers already know their own sex, and children become more aware of gender with every passing year of childhood (Maccoby, 1998).

Social scientists attempt to distinguish between sex differences, which are the biological differences between males and females, and gender differences, which are culturally imposed masculine or feminine roles and behaviors. In the- ory, this may seem like a straightforward separation, but, as with every nature– nurture distinction, the interaction between sex and gender makes it hard to sepa- rate the two (Hines, 2004).

Even 2-year-olds can apply gender labels (Mrs., Mr., lady, man) consistently. That simple cognitive awareness becomes, by age 3, a rudimentary understanding that sex distinctions are lifelong (although some pretend, hope, or imagine other- wise). By age 4, children are convinced that certain toys (such as dolls or trucks) and certain roles (such as nurse or soldier) are appropriate for one gender but not the other (Bauer et al., 1998; Ruble et al., 2006).

Throughout the play years, children confuse gender and sex. Awareness that a person’s sex is a biological characteristic, not determined by words, opinions, or clothing, develops gradually, becoming firm at age 8 or so (Szkrybalo & Ruble, 1999). This uncertainty about the biological determination of sex was demon- strated by a 3-year-old who went with his father to see a neighbor’s newborn kittens. Returning home, the child told his mother that there were three girl kit- tens and two boy kittens. “How do you know?” she asked. “Daddy picked them up and read what was written on their tummies,” he replied.