hypnosis

Exploring PSYCHOLOGY

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INTERNATIONAL EDITION

Special Contributor

C. Nathan DeWall, University of Kentucky

WORTH PUBLISHERS

Hope College Holland, Michigan

David G. Myers

Exploring PSYCHOLOGY

NINTH EDITION

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Senior Vice President, Editorial and Production: Catherine Woods Publisher: Kevin Feyen Executive Marketing Manager: Katherine Nurre Development Editors: Christine Brune, Nancy Fleming Director of Print and Digital Development: Tracey Kuehn Media Editor: Elizabeth Block Supplements Editors: Betty Probert, Nadina Persaud Photo Editor: Bianca Moscatelli Photo Researcher: Donna Ranieri Art Director: Babs Reingold Cover Designers: Lyndall Culbertson and Babs Reingold Interior and Chapter Opener Designer: Charles Yuen Layout Designer: Lee Ann McKevitt Cover Photo Illustrator: Lyndall Culbertson Associate Managing Editor: Lisa Kinne Project Editor: Jeanine Furino Marketing Assistant: Julie Tompkins Illustration Coordinators: Bill Page, Janice Donnola Illustrations: TSI Graphics, Keith Kasnot, Todd Buck Production Manager: Sarah Segal Composition: TSI Graphics Printing and Binding: RR Donnelley

Library of Congress Control Number: 2012948473

Hardcover: ISBN-13: 978-1-4292-6679-6 ISBN-10: 1-4292-6679-1 Paperback: ISBN-13: 978-1-4641-1172-3 ISBN-10: 1-4641-1172-3 Loose-Leaf: ISBN-13: 978-1-4641-0840-2 ISBN-10: 1-4641-0840-4 PI edition: ISBN-13: 978-1-4641-4705-0 ISBN-10: 1-4641-4705-1

© 2014, 2011, 2008, 2005 by Worth Publishers

All rights reserved.

Printed in the United States of America

All royalties from the sale of this book are assigned to the David and Carol Myers Foundation, which exists to receive and distribute funds to other charitable organizations.

Worth Publishers Macmillan Higher Education 41 Madison Avenue Houndmills, Basingstoke New York, NY 10010 RG21 6XS, England www.worthpublishers.com www.macmillanhighered.com/

international

Photo Credits: Cover: Profi le of smiling woman: JGI/Jamie Grill/Getty Images; Man taking a photo: Pedro Vidal/Shutterstock; Mother with baby daughter: Erik Isakson/age fotostock; Circus juggler: RubberBall/SuperStock; Chapter 1: pp. viii, xlii–1, 31, 33: Spiral: Charles Yuen; Water: Photodisc/Getty Images; Rabbit: Mike Kemp/ Getty Images; Magnifying glass: Charles Yuen; MRI: Living Art Enterprises, LLC/Photo Researchers, Inc.; Infant: Lane Oatey/Getty Images; Man holding boxes: Erik Isakson/ age fotostock; Girl studying: OJO Images Ltd/Alamy. Chapter 2: pp. viii, 34–35 and 72, 75: Circuit boards: Charles Yuen; Female kicking: Lev Olkha /Shutterstock; Fox: Eric Isselée/Shutterstock; Brain scan: Zephyr/Photo Researchers, Inc.; Butterfl y: Dim154/ Shutterstock. Chapter 3: pp. ix, 76–77 and 113, 115: Butterfl ies: Svetlana Larina/ istockphoto; Butterfl ies: polarica/istockphoto; Cup of coffee: Vasca/Shutterstock; Sleeping toddler: swissmacky/Shutterstock; Woman meditating: INSADCO Photography/Alamy. Chapter 4: pp. ix, 116–117 and 159, 161: Bucket in sand: René/istockphoto; Beach and palm tree: Charles Yuen; Beach ball: WendellandCarolyn/istockphoto; Mother helping daugh- ter with homework: Indeed/Getty Images; Teens texting: Allan Shoemake/Getty Images; Bride and groom: bluehand/Shutterstock; Mother holding baby: Erik Isakson/age fotostock; Baby being fed with spoon: Asia Images/Getty Images. Chapter 5: pp. ix, 162–163 and 187, 189: Petri dish: Samuel Ashfi eld/Photo Researchers, Inc.; Chromosomes: Pasieka/ Photo Researchers, Inc.; Swans: The Boston Globe/John Tlumacki; Dad and child: MGP/ Getty Images; Teenagers of different heights: Rob Lewine/Getty Images; She-male: vita khorzhevska/Shutterstock; Teenage couple: Petrenko Andriy/Shutterstock. Chapter 6: pp. x, 190–191 and 232, 235: Herbs: Ivonne Wierink/Shutterstock; Herbs: Margrit Hirsch/ Shutterstock; Citrus: Lauren Burke/Jupiterimages; Man with cello: sbarabu/Shutterstock; Child kissing mother’s face: Jose Luis Pelaez, Inc./Blend Images/Corbis; Woman holding fl ower: Asia Images Group/Superstock. Chapter 7: pp. x, 236–237 and 267, 269: Nest with eggs: Duncan Usher/Foto Natura/Getty Images; Trees: Yuriy Kulyk/Shutterstock, Tungphoto/Shutterstock, irin-k/Shutterstock, Perfect Picture Parts/Alamy; Cat: Eric Isselée/Shutterstock; Pigeon: Vitaly Titov & Maria SideInikova/Shutterstock; Kids playing videogames: Stanislav Sointsev/Getty Images; Dog doing stunts: Marina Jay/Shutterstock; Girl on laptop: Lauren Burke/Getty Images; People with books on heads: Image Source/ SuperStock. Chapter 8: pp. xi, 270–271 and 301, 303: Film strips: Charles Yuen; Mouse trap: Darren Matthews/Alamy; Cookie: Jean Sandler/FeaturePics; Girl studying: Sigrid Olsson/PhotoAlto/Corbis; Man taking photo: Pedro Vidal/Shutterstock; Hot air balloon: D. Hurst/Alamy. Chapter 9: pp. xi, 304–305 and 347, 349: Various balls: Charles Yuen; Woman running hurdles: Ocean/Corbis; Man doing crossword: Ann Baldwin/Shutterstock; Puzzle pieces: Alexey Lebedev/Shutterstock; Woman shooting basketball: Blend Images/ Jupiterimages; Man playing saxophone: Masterfi le (Royalty-Free Division); Elephant: Johan Swanepoel/Alamy. Chapter 10: pp. xii, 350–351 and 386: Vietnam landscape: Charles Yuen; Girl using cell phone: Thomas Northcut/Jupiterimages; Woman on treadmill: PhotoObjects.net/Jupiterimages; Teenage boys: Photodisc/Jupiterimages; Woman with arms raised: Mark Andersen/agefotostock. Chapter 11: pp. xii, 389–390 and 419, 421: Fruit and vegetables: Charles Yuen; Two women laughing: Mark Andersen/Getty Images; Man look- ing angry: PhotoSpin, Inc./Alamy; Man kissing dog: Photos.com/Getty Images; Man medi- tating: Dean Mitchell/Shutterstock; Woman touching ground: IMAGEMORE/agefotostock: Nun praying: PhotosIndia.com LLC/Alamy; Tissues, aspirin: D. Hurst/Alamy. Chapter 12: pp. xiii, 422–423 and 453, 455: Masks: Charles Yuen, Bartosz Hadyniak/istockphoto, Perry Correll/Shutterstock, brytta/istockphoto, Hemera Technologies/Jupiterimages; Happy dog: Erik Lam/Shutterstock; Centaur: Liquidlibrary/Jupiterimages; Girl: Timothy Large/Shutterstock; Circus juggler: RubberBall/Superstock. Chapter 13: pp. xiii, 456–457 and 501, 503: Aerial beach scene: Brand X Pictures; Football: Todd Taulman/ Shutterstock; Blog links: Lada Adamic and Natalie Glance; Wrench: Punchstock/Corbis; Gaming console: Microsoft Corporation; Tattooed arm: David Katzenstein/Photolibrary; Dancing couple: Photodisc/Jupiterimages. Chapter 14: pp. xiii, 504–505 and 541: Upset woman: Wavebreakmedia Ltd/Jupiterimages; Eyes: Blend Images/Alamy, Photodisc/ Getty Images; Tarantula: Martin Harvey/Jupiterimages; Snake: Hemera Technologies/ Jupiterimages; Blindfolded woman leading man: Erik Isakson/age footstock; Depressed man: Image Source/Getty Images. Chapter 15: pp. xiv, 544–545 and 578, 580: Crocus fl ow- ers through snow: Myotis/Shutterstock; Couple on bicycle: RubberBall/SuperStock; Healthy woman: RubberBall/Nicole Hill/Jupiterimages; People in rainforest: Randy Faris/Corbis.

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For Sara Neevel with gratitude for your meticulous support, and for your friendship

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vi PREFACE

DAVID MYERS received his psychology Ph.D. from the Univer- sity of Iowa. He has spent his career at Hope College in Michigan, where he has taught dozens of introductory psychology sections. Hope College students have invited him to be their commencement speaker and voted him “outstanding professor.”

His research and writings have been recognized by the Gordon Allport Intergroup Relations Prize, by a 2010 Honored Scientist award from the Federation of Associations in Behavioral & Brain Sciences, by a 2010 Award for Service on Behalf of Personality and Social Psychology, and by three honorary doctorates.

Myers’ scientific articles have, with support from National Science Foun- dation grants, appeared in three dozen scientific periodicals, including Science, American Scientist, Psychological Science, and the American Psycholo- gist. In addition to his scholarly writing and his textbooks for introduc- tory and social psychology, he also digests psychological science for the general public. His writings have appeared in four dozen magazines, from Today’s Education to Scientific American. He also has authored five general audience books, including The Pursuit of Happiness and Intuition: Its Powers and Perils.

David Myers has chaired his city’s Human Relations Commission, helped found a thriving assistance center for families in poverty, and spoken to hundreds of college and community groups. Drawing on his experience, he also has written three dozen articles and a book (A Quiet World) about hearing loss, and he is advocating a transformation in American assis- tive listening technology (see www.hearingloop.org). For his leadership, he received an American Academy of Audiology Presidential Award in 2011, and the Hearing Loss Association of America Walter T. Ridder Award in 2012.

He bikes to work year-round and plays regular pick-up basketball. David and Carol Myers have raised two sons and a daughter, and have one granddaughter.

ABOUT THE AUTHORABOUT THE AUTHOR

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PREFACE vii

BRIEF CONTENTS

Preface . . . xv

Time Management: Or, How to Be a Great Student and Still Have a Life . . . xxxiv

CHAPTER 1 Thinking Critically With Psychological Science . . . 1

CHAPTER 2 The Biology of Behavior . . . 35

CHAPTER 3 Consciousness and the Two-Track Mind . . . 77

CHAPTER 4 Developing Through the Life Span . . . 117

CHAPTER 5 Gender and Sexuality . . . 163

CHAPTER 6 Sensation and Perception . . . 191

CHAPTER 7 Learning . . . 237

CHAPTER 8 Memory . . . 271

CHAPTER 9 Thinking, Language, and Intelligence . . . 305

CHAPTER 10 Motivation and Emotion . . . 351

CHAPTER 11 Stress, Health, and Human Flourishing . . . 389

CHAPTER 12 Personality . . . 423

CHAPTER 13 Social Psychology . . . 457

CHAPTER 14 Psychological Disorders . . . 505

CHAPTER 15 Therapy . . . 545

APPENDIX A Statistical Reasoning in Everyday Life . . . A-1

APPENDIX B Psychology at Work . . . B-1

APPENDIX C Subfi elds of Psychology . . . C-1

APPENDIX D Complete Chapter Reviews . . . D-1

APPENDIX E Answers to Experience the Testing Effect Questions . . . E-1

Glossary . . . G-1

References . . . R-1

Name Index . . . NI-1

Subject Index . . . SI-1 vii

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Preface . . . xv

Time Management: Or, How to Be a Great Student and Still Have a Life . . . xxxiv

Thinking Critically With Psychological Science . . . 1

CHAPTER1 What Is Psychology? . . . 2

Psychology’s Roots . . . 2

Contemporary Psychology . . . 5 Psychology’s Biggest Question . . . 5

Psychology’s Three Main Levels of Analysis . . . 6

Psychology’s Subfi elds . . . 8

The Need for Psychological Science . . . 10 What About Intuition and Common Sense? . . . 10

The Scientifi c Attitude: Curious, Skeptical, and Humble . . . 13

Critical Thinking . . . 15

How Do Psychologists Ask and Answer Questions? . . . 15

The Scientifi c Method . . . 15

Description . . . 17

Correlation . . . 20

Experimentation . . . 22

Frequently Asked Questions About Psychology . . . 25

Improve Your Retention—and Your Grades . . . 29

The Biology of Behavior . . . 35

CHAPTER2 Biology and Behavior . . . 36

Neural Communication . . . 36 Neurons . . . 36

The Neural Impulse . . . 37

How Neurons Communicate . . . 38

How Neurotransmitters Infl uence Us . . . 40

The Nervous System . . . 41 The Peripheral Nervous System . . . 42

The Central Nervous System . . . 44

The Endocrine System . . . 45

The Brain . . . 46 Older Brain Structures . . . 47

CLOSE UP: The Tools of Discovery—Having Our Head Examined . . . . 48

The Cerebral Cortex . . . 53

Our Divided Brain . . . 59

Right-Left Differences in the Intact Brain . . . 61

Behavior Genetics: Predicting Individual Differences . . . 62

Genes: Our Codes for Life . . . 62

Twins and Adoption Studies . . . 63

Gene-Environment Interaction . . . 67

Evolutionary Psychology: Understanding Human Nature . . . 68

Natural Selection and Adaptation . . . 69

Evolutionary Success Helps Explain Similarities . . . 70

viii

CONTENTSCONTENTS

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CONTENTS ix

Consciousness and the Two- Track Mind . . . 77

CHAPTER3 The Brain and Consciousness . . . 78

Dual Processing: The Two-Track Mind . . . 79

Selective Attention . . . 80

Sleep and Dreams . . . 83 Biological Rhythms and Sleep . . . 83

Sleep Theories . . . 88

Sleep Deprivation and Sleep Disorders . . . 89

Dreams . . . 93

Hypnosis . . . 97 Frequently Asked Questions About Hypnosis . . . 97

Explaining the Hypnotized State . . . 98

Drugs and Consciousness . . . 100 Tolerance, Dependence, and Addiction . . . 100

THINKING CRITICALLY ABOUT: Addiction . . . 101

Types of Psychoactive Drugs . . . 102

Infl uences on Drug Use . . . 109

Developing Through the Life Span . . . 117

CHAPTER4 Developmental Psychology’s Major Issues . . . 118

Prenatal Development and the Newborn . . . 118 Conception . . . 118

Prenatal Development . . . 119

The Competent Newborn . . . 120

Infancy and Childhood . . . 121 Physical Development . . . 121

Cognitive Development . . . 124

CLOSE UP: Autism and “Mind-Blindness” . . . 130

Social Development . . . 132

Refl ections on Nature and Nurture . . . 139

Adolescence . . . 140 Physical Development . . . 140

Cognitive Development . . . 141

Social Development . . . 143

THINKING CRITICALLY ABOUT: How Much Credit or Blame Do Parents Deserve? . . . 147

Emerging Adulthood . . . 148

Refl ections on Continuity and Stages . . . 149

Adulthood . . . 150 Physical Development . . . 150

Cognitive Development . . . 153

Social Development . . . 154

Refl ections on Stability and Change . . . 158

Gender and Sexuality . . . 163

CHAPTER5 Gender Development . . . 164

Genes: How Are We Alike? How Do We Differ? . . . 164

The Nature of Gender: Our Biology . . . 167

The Nurture of Gender: Our Culture . . . 169

Human Sexuality . . . 171 The Physiology of Sex . . . 171

The Psychology of Sex . . . 175

CLOSE UP: The Sexualization of Girls . . . 177

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x CONTENTS

Sexual Orientation . . . 178 Environment and Sexual Orientation . . . 179

Biology and Sexual Orientation . . . 180

An Evolutionary Explanation of Human Sexuality . . . 183

Gender Differences in Sexuality . . . 183

Natural Selection and Mating Preferences . . . 184

Critiquing the Evolutionary Perspective . . . 185

Refl ections on Gender, Sexuality, and Nature–Nurture Interaction . . . 185

Sensation and Perception . . . 191

CHAPTER6 Basic Principles of Sensation and Perception . . . 192

Transduction . . . 192

Thresholds. . . 193

THINKING CRITICALLY ABOUT: Can Subliminal Messages Control Our Behavior? . . . 195

Sensory Adaptation . . . 196

Perceptual Set . . . 197

Context Effects . . . 198

Emotion and Motivation . . . 199

Vision . . . 200 The Stimulus Input: Light Energy . . . 200

The Eye . . . 200

Visual Information Processing . . . 202

Color Vision . . . 206

Visual Organization . . . 208

Visual Interpretation . . . 214

Hearing . . . 216 The Stimulus Input: Sound Waves . . . 216

The Ear. . . 216

The Other Senses . . . 220 Touch . . . 220

Pain . . . 220

Taste . . . 224

Smell . . . 225

Body Position and Movement . . . 227

Sensory Interaction . . . 227 THINKING CRITICALLY ABOUT: ESP—Perception

Without Sensation? . . . 230

Learning . . . 237

CHAPTER7 How Do We Learn? . . . 238

Classical Conditioning . . . 239 Pavlov’s Experiments . . . 240

Pavlov’s Legacy . . . 244

Operant Conditioning . . . 246 Skinner’s Experiments . . . 246

Skinner’s Legacy . . . 253

CLOSE UP: Training Our Partners . . . 255

Contrasting Classical and Operant Conditioning . . . 255

Biology, Cognition, and Learning . . . 256 Biological Constraints on Conditioning . . . 256

Cognition’s Infl uence on Conditioning . . . 259

Learning by Observation . . . 261 Mirrors and Imitation in the Brain . . . 262

Applications of Observational Learning . . . 263

THINKING CRITICALLY ABOUT: Does Viewing Media Violence Trigger Violent Behavior? . . . 265

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CONTENTS xi

Memory . . . 271

CHAPTER8 Studying Memory . . . 272

Memory Models . . . 273

Building Memories: Encoding . . . 274 Dual-Track Memory: Effortful Versus Automatic

Processing . . . 274

Automatic Processing and Implicit Memories . . . 275

Effortful Processing and Explicit Memories . . . 275

Memory Storage . . . 280 Retaining Information in the Brain . . . 281

Synaptic Changes . . . 283

Retrieval: Getting Information Out . . . 285 Measuring Retention . . . 285

Retrieval Cues . . . 286

Forgetting . . . 289 Forgetting and the Two-Track Mind . . . 290

Encoding Failure . . . 291

Storage Decay . . . 291

Retrieval Failure . . . 292

Memory Construction Errors . . . 294 Misinformation and Imagination Effects . . . 295

Source Amnesia . . . 296

Discerning True and False Memories . . . 297

Children’s Eyewitness Recall . . . 297

Repressed or Constructed Memories of Abuse? . . . 298

Improving Memory . . . 299

Thinking, Language, and Intelligence . . . 305

CHAPTER9 Thinking . . . 306

Concepts . . . 306

Problem Solving: Strategies and Obstacles . . . 307

Forming Good and Bad Decisions and Judgments . . . 308

THINKING CRITICALLY ABOUT: The Fear Factor—Why We Fear the Wrong Things . . . 310

Thinking Creatively . . . 314

CLOSE UP: Fostering Your Own Creativity . . . 315

Do Other Species Share Our Cognitive Skills? . . . 316

Language . . . 318 Language Structure . . . 318

Language Development . . . 319

The Brain and Language . . . 322

Do Other Species Have Language? . . . 323

Thinking and Language . . . 326 Language Infl uences Thinking . . . 326

Thinking in Images . . . 328

Intelligence . . . 329 What Is Intelligence? . . . 329

Assessing Intelligence . . . 333

Aging and Intelligence . . . 337

CLOSE UP: Extremes of Intelligence . . . 338

Genetic and Environmental Infl uences on Intelligence . . . 339

Group Differences in Intelligence Test Scores . . . 342

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xii CONTENTS

Motivation and Emotion . . . 351

CHAPTER10 Motivational Concepts . . . 352

Instincts and Evolutionary Psychology . . . 352

Drives and Incentives . . . 353

Optimum Arousal . . . 353

A Hierarchy of Motives . . . 355

Hunger . . . 356 The Physiology of Hunger . . . 357

The Psychology of Hunger . . . 359

Obesity and Weight Control . . . 361

CLOSE UP: Waist Management . . . 363

The Need to Belong . . . 364 The Benefi ts of Belonging . . . 364

The Pain of Being Shut Out . . . 365

Connecting and Social Networking . . . 367

CLOSE UP: Managing Your Social Networking . . . 369

Achievement Motivation . . . 370

Emotion: Arousal, Behavior, and Cognition . . . 371

Historical Emotion Theories . . . 372

Schachter–Singer Two Factor Theory: Arousal + Label = Emotion . . . 373

Zajonc, LeDoux, and Lazarus: Does Cognition Always Precede Emotion? . . . 374

Embodied Emotion . . . 376 The Basic Emotions . . . 376

Emotions and the Autonomic Nervous System . . . 377

The Physiology of Emotions . . . 377

THINKING CRITICALLY ABOUT: Lie Detection . . . 379

Expressed and Experienced Emotion . . . 378 Detecting Emotion in Others . . . 379

Gender and Emotion . . . 381

Culture and Emotion . . . 382

The Effects of Facial Expressions . . . 384

Stress, Health, and Human Flourishing . . . 389

CHAPTER11 Stress and Health . . . 390

Stress: Some Basic Concepts . . . 390

Stress and Illness . . . 394

CLOSE UP: Tips for Handling Anger . . . 398

Coping With Stress . . . 401 Personal Control . . . 401

Optimism Versus Pessimism . . . 404

Social Support . . . 405

CLOSE UP: Pets Are Friends, Too . . . 408

Reducing Stress . . . 407 Aerobic Exercise . . . 407

Relaxation and Meditation . . . 409

Faith Communities and Health . . . 410

Happiness . . . 412 Positive Psychology . . . 413

What Affects Our Well-Being? . . . 414

What Predicts Our Happiness Levels? . . . 417

CLOSE UP: Want to Be Happier? . . . 418

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CONTENTS xiii

Personality . . . 423

CHAPTER12 The Psychodynamic Theories . . . 424

Freud’s Psychoanalytic Perspective: Exploring the Unconscious . . . 424

The Neo-Freudian and Psychodynamic Theorists . . . 424

Assessing Unconscious Processes . . . 424

Evaluating Freud’s Psychoanalytic Perspective and Modern Views of the Unconscious . . . 424

Humanistic Theories . . . 432 Abraham Maslow’s Self-Actualizing Person . . . 433

Carl Rogers’ Person-Centered Perspective . . . 433

Assessing the Self . . . 434

Evaluating Humanistic Theories . . . 434

Trait Theories . . . 435 Exploring Traits . . . 436

Assessing Traits . . . 437

THINKING CRITICALLY ABOUT: How to Be a “Successful” Astrologer or Palm Reader . . . 438

The Big Five Factors . . . 439

Evaluating Trait Theories . . . 441

Social-Cognitive Theories . . . 443 Reciprocal Infl uences . . . 443

Assessing Behavior in Situations . . . 445

Evaluating Social-Cognitive Theories . . . 445

Exploring the Self . . . 446 The Benefi ts of Self-Esteem . . . 447

Self-Serving Bias . . . 448

Culture and the Self . . . 450

Social Psychology . . . 457

CHAPTER13 Social Thinking . . . 458

The Fundamental Attribution Error . . . 458

Attitudes and Actions . . . 460

Social Infl uence . . . 463 Cultural Infl uences . . . 463

Conformity: Complying With Social Pressures . . . 465

Obedience: Following Orders . . . 467

Group Behavior . . . 471

Social Relations . . . 475 Prejudice . . . 476

CLOSE UP: Automatic Prejudice . . . 477

Aggression . . . 481

Attraction . . . 487

CLOSE UP: Online Matchmaking and Speed Dating . . . 488

Altruism . . . 493

Confl ict and Peacemaking . . . 496

Psychological Disorders . . . 505

CHAPTER14 What Is a Psychological Disorder? . . . 506

Understanding Psychological Disorders . . . 506

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xiv CONTENTS

THINKING CRITICALLY ABOUT: ADHD—Normal High Energy or Genuine Disorder? . . . 507

Classifying Disorders—and Labeling People . . . 509

THINKING CRITICALLY ABOUT: Insanity and Responsibility . . . 512

Anxiety Disorders . . . 512 Generalized Anxiety Disorder . . . 513

Panic Disorder . . . 513

Phobias . . . 513

Obsessive-Compulsive Disorder . . . 514

Post-Traumatic Stress Disorder . . . 515

Understanding Anxiety Disorders . . . 516

Mood Disorders . . . 519 Major Depressive Disorder . . . 520

Bipolar Disorder . . . 520

Understanding Mood Disorders . . . 521

CLOSE UP: Suicide and Self-Injury . . . 524

Schizophrenia . . . 528 Symptoms of Schizophrenia . . . 528

Onset and Development of Schizophrenia . . . 529

Understanding Schizophrenia . . . 530

Other Disorders . . . 534 Dissociative Disorders . . . 534

Eating Disorders . . . 536

Personality Disorders . . . 537

Rates of Psychological Disorders . . . 540

Therapy . . . 545

CHAPTER15 Treating Psychological Disorders . . . 546

The Psychological Therapies . . . 546 Psychoanalysis and Psychodynamic

Therapy . . . 547

Humanistic Therapies . . . 548

Behavior Therapies . . . 550

Cognitive Therapies . . . 554

Group and Family Therapies . . . 557

Evaluating Psychotherapies . . . 559 Is Psychotherapy Effective? . . . 560

Which Psychotherapies Work Best? . . . 562

Evaluating Alternative Therapies . . . 563

How Do Psychotherapies Help People? . . . 565

Culture and Values in Psychotherapy . . . 566

CLOSE UP: A Consumer’s Guide to Mental Health Professionals . . . 567

The Biomedical Therapies . . . 568 Drug Therapies . . . 568

Brain Stimulation . . . 571

Psychosurgery . . . 574

Therapeutic Lifestyle Change . . . 574

Preventing Psychological Disorders . . . 576 Resilience . . . 576

Creating Healthy Environments . . . 577

APPENDIX A: Statistical Reasoning in Everyday Life . . . A-1

APPENDIX B: Psychology at Work . . . B-1

APPENDIX C: Subfi elds of Psychology . . . C-1

APPENDIX D: Complete Chapter Reviews . . . D-1

APPENDIX E: Answers to Experience the Testing Effect Questions . . . E-1

Glossary . . . G-1

References . . . R-1

Name Index . . . NI-1

Subject Index . . . SI-1

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PREFACE

Throughout its nine editions, my unwavering vision for Exploring Psychology has been to merge rigorous science with a broad human perspective that engages both mind and heart. I aim to offer a state-of-the-art introduction to psychological science that speaks to students’ needs and interests. I aspire to help students understand and appreciate the wonders of their everyday lives. And I seek to convey the inquisitive spirit with which psychologists do psychology.

I am genuinely enthusiastic about psychology and its applicability to our lives. Psychological science has the potential to expand our minds and enlarge our hearts. By studying and applying its tools, ideas, and insights, we can supplement our intuition with critical thinking, restrain our judgmentalism with compas- sion, and replace our illusions with understanding. By the time students complete this guided tour of psychology, they will also, I hope, have a deeper understand- ing of our moods and memories, about the reach of our unconscious, about how we f lourish and struggle, about how we perceive our physical and social worlds, and about how our biology and culture in turn shape us. (See TABLES 1 and 2, next page.)

Believing with Thoreau that “anything living is easily and naturally expressed in popular language,” I seek to communicate psychology’s scholarship with crisp narra- tive and vivid storytelling. “A writer’s job,” says my friend Mary Pipher, “is to tell stories that connect readers to all the people on Earth, to show these people as the complicated human beings they really are, with histories, families, emotions, and legitimate needs.” Writing as a solo author, I hope to tell psychology’s story in a way that is warmly personal as well as rigorously scientific. I love to ref lect on connec- tions between psychology and other realms, such as literature, philosophy, history, sports, religion, politics, and popular culture. And I love to provoke thought, to play with words, and to laugh. For his pioneering 1891 Principles of Psychology, William James sought “humor and pathos.” And so do I.

I am grateful for the privilege of assisting with the teaching of this mind- expanding discipline to so many students, in so many countries, through so many different languages. To be entrusted with discerning and communicating psychol- ogy’s insights is both an exciting honor and a great responsibility.

Creating this book is a team sport. Like so many human achievements, it is the product of a collective intelligence. Woodrow Wilson spoke for me: “I not only use all the brains I have, but all I can borrow.” The thousands of instructors and millions of students across the globe who have taught or studied (or both!) with this book have contributed immensely to its development. Much of this contribu- tion has occurred spontaneously, through correspondence and conversations. For this edition, we also formally involved 1061 researchers and teaching psycholo- gists, and 251 students, in our efforts to gather accurate and up-to-date information about the f ield of psychology and the content, study aids, and supplements needs of instructors and students in the introductory course. We look forward to continuing feedback as we strive, over future editions, to create an ever better book and teach- ing package.

What’s NEW? This ninth edition is the most carefully reworked and extensively updated of all the revisions to date. This new edition features improvements to the organization and presentation, especially to our system of supporting student learning and remembering.

xv

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xvi PREFACE

TABLE 1 Evolutionary Psychology and Behavior Genetics

The evolutionary perspective is covered on the following pages:

TABLE 2 Neuroscience

In addition to the coverage found in Chapter 2, neuroscience can be found on the following pages:

Aggression, pp. 482–483 Aging: physical exercise and the brain, p. 152 Animal language, pp. 316–317 Antisocial personality disorder, pp. 538–539 Arousal, pp. 175–176 Attention-deficit hyperactivity disorder

(ADHD) and the brain, p. 507 Autism, pp. 130–131 Automatic prejudice: amygdala, p. 477 Biofeedback, p. 409 Biopsychosocial approach, pp. 6–7

aggression, p. 487 aging, pp. 152, 157, 291 dementia and Alzheimer’s, p. 284 development, pp. 186–187 dreams, pp. 93–94 drug use, pp. 109–112 emotion, pp. 141, 283, 374–375, 378,

381–382 hypnosis, pp. 99–100 learning, pp. 256–260 pain, pp. 222–223 personality, p. 444 psychological disorders, p. 508 sleep, pp. 83–88 therapeutic lifestyle change, pp. 574–575

Brain development: adolescence, p. 140 experience and, pp. 122–123 infancy and childhood, p. 124 sexual differentiation in utero, p. 169

Brain stimulation therapies, pp. 572–573

Cognitive neuroscience, pp. 4, 78 Drug dependence, pp. 109–111 Emotion and cognition, pp. 371–372 Emotional intelligence and brain damage,

p. 333 Fear learning, p. 518 Fetal alcohol syndrome and brain abnor-

malities, p. 120 Hallucinations: pp. 107–108 Hallucinations and:

near-death experiences, pp. 107–108 schizophrenia, p. 529 sleep, p. 95

Hormones and: abuse, pp. 136–137 appetite, pp. 357–358 development, p. 167 in adolescents, pp. 167, 140–141 of sexual characteristics, pp. 167–168 emotion, pp. 378–379 gender, p. 167 sex, pp. 150–151 sexual behavior, pp. 171–173 stress, pp. 377, 391–393, 394–396, 405 weight control, p. 359

Hunger, p. 357 Insight, pp. 307–308 Intelligence, p. 334

creativity, pp. 314–315 twins, pp. 339–340

Language, pp. 318, 322–323 and deafness, p. 322 and thinking in images, p. 328

Light-exposure therapy: brain scans, p. 564 Meditation, pp. 409–410 Memory:

emotional memories, p. 283 explicit memories, pp. 281–282 implicit memories, pp. 282–283 physical storage of, pp. 280–282 and sleep, pp. 88, 95 and synaptic changes, pp. 283–285

Mirror neurons, pp. 262–263 Neuroscience perspective, defined, p. 7 Neurotransmitters and:

anxiety disorders, pp. 518, 569 biomedical therapy:

depression, pp. 523–525, 569–570 ECT, pp. 571–572 schizophrenia, pp. 530, 568–569

child abuse, p. 137 cognitive-behavioral therapy: obsessive-

compulsive disorder, p. 557 depression, pp. 523–525 drugs, pp. 100, 102 exercise, p. 407 narcolepsy, pp. 92–93 schizophrenia, pp. 530, 532

Observational learning and brain imaging, p. 261

Optimum arousal: brain mechanisms for rewards, pp. 353–355

Orgasm, p. 173 Pain, p. 220

phantom limb pain, p. 222 virtual reality, pp. 223–224

Parallel vs. serial processing, p. 205 Perception:

brain damage and, p. 205 color vision, pp. 206–208 feature detection, p. 204 transduction, p. 192 visual information processing,

pp. 200–202 Perceptual organization, pp. 208–211 Personality and brain-imaging, p. 437 Post-traumatic stress disorder

(PTSD) and the limbic system, pp. 515–516

Psychosurgery: lobotomy, p. 574 Schizophrenia and brain abnormalities,

pp. 530–531, 532 Sensation:

body position and movement, p. 227 deafness, pp. 217–218 hearing, pp. 216–217 sensory adaptation, p. 196 smell, pp. 225–226 taste, pp. 224–225 touch, p. 220 vision, p. 200

Sexual orientation, pp. 180, 182 Sleep:

cognitive development and, p. 96 memory and, p. 88 recuperation during, p. 88

Smell and emotion, p. 226 Unconscious mind, pp. 431–432

Aging, pp. 151–152 Anxiety disorders, p. 518 Biological predispositions:

in learning, pp. 256–260 in operant conditioning, pp. 258–260

Brainstem, p. 47 Consciousness, p. 78 Darwin, Charles, p. 6 Depression and light exposure therapy, p. 564 Emotion, effects of facial expressions and,

pp. 384–385 Emotional expression, pp. 382–383 Evolutionary perspective, defined, p. 7 Exercise, pp. 407–408 Fear, p. 310 Feature detection, p. 204 Hearing, p. 216 Hunger and taste preference, p. 359 Instincts, p. 352 Intelligence, pp. 329–331, 333–334,

343–346 Language, pp. 318–319, 320–322 Love, pp. 154–156 Math and spatial ability, pp. 342–343 Mating preferences, pp. 184–185 Menopause, pp. 150–151 Need to belong, p. 364 Obesity, p. 461

Overconfidence, pp. 311–312 Perceptual adaptation, p. 215 Puberty, onset of, pp. 148–149 Sensation, p. 192 Sensory adaptation, p. 196 Sexual orientation, p. 181 Sexuality, pp. 173, 183–184 Sleep, pp. 84, 88 Smell, pp. 225–226 Taste, pp. 224–225

See also Chapter 2, The Biology of Behavior.

Abuse, intergenerational transmission of, p. 264

Adaptability, p. 53 Aggression, pp. 579–580

intergenerational transmission of, p. 264 Autism, pp. 130–131 Behavior genetics perspective, p. 7 Biological perspective, p. 36 Brain plasticity, p. 58 Continuity and stages, p. 149 Deprivation of attachment, p. 136 Depth perception, p. 210 Development, p. 119 Drives and incentives, p. 353 Drug dependence, p. 110 Drug use, pp. 109–112 Eating disorders, p. 536 Epigenetics, p. 120 Happiness, pp. 412–413 Hunger and taste preference, pp. 359–360 Intelligence:

Down syndrome, pp. 338–339 genetic and environmental influences,

pp. 339–346 Learning, pp. 256–257, 258–259 Motor development, p. 123 Nature–nurture, pp. 5–6

twins, p. 6

Obesity and weight control, pp. 361–362 Parenting styles, p. 138 Perception, pp. 214–215 Personality traits, p. 437–440 Psychological disorders and:

ADHD, p. 507 anxiety disorders, p. 517 biopsychosocial approach, p. 508 depression, p. 523 insanity and responsibility, p. 512 mood disorders, pp. 523–524 personality disorders, pp. 538–539 post-traumatic stress syndrome,

pp. 515–516 schizophrenia, pp. 531–533

Reward deficiency syndrome, p. 52 Romantic love, pp. 154–156 Sexual disorders, pp. 173–174 Sexual orientation, p. 180 Sexuality, p. 173 Sleep patterns, p. 87 Smell, pp. 225–226 Stress, personality, and illness, pp. 397–399

managing stress with exercise, pp. 407–409 Traits, pp. 341-342

See also Chapter 2, The Biology of Behavior.

TTT

Behavior genetics is covered on the following pages:

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PREFACE xvii

NEW Study System Follows Best Practices From Learning and Memory Research The new learning system harnesses the testing effect, which documents the benefits of actively retrieving information through self-testing (FIGURE 1). Thus, each chap- ter now offers 15 to 20 new Retrieve It questions interspersed throughout. Creating these desirable difficulties for students along the way optimizes the testing effect, as does immediate feedback (via inverted answers beneath each question).

In addition, each main section of text begins with numbered questions that establish learning objectives and direct student reading. The Chapter Review section repeats these questions as a further self-testing opportunity (with answers in the Complete Chapter Reviews appendix). The Chapter Review section also offers a page-referenced list of key terms and concepts, and new Experience the Testing Effect questions in multiple formats to promote optimal retention.

FIGURE 1 Testing effect For suggestions of how students may apply the testing effect to their own learning, watch this 5-minute YouTube animation: www.tinyurl.com/HowToRemember

Nearly 1000 New Research Citations My ongoing scrutiny of dozens of scientific periodicals and science news sources, enhanced by commissioned reviews and countless e-mails from instructors and students, enables my integrating our field’s most important, thought-provoking, and student-relevant new discoveries. Part of the pleasure that sustains this work is learning something new every day! (For a complete list of significant changes to the content, see www.worthpub.com/myers.)

Reorganized Chapters In addition to the new study aids and updated coverage, I’ve introduced the following organizational changes:

• Chapter 1 concludes with a new section, “Improve Your Retention—And Your Grades.” This guide will help students replace ineffective and inefficient old habits with new habits that increase retention and success.

• The contents of the previous edition’s Nature, Nurture, and Human Diversity chap- ter are now integrated throughout the text, including in Chapters 2, 4, 5, 12, and 13. (See Table 4 on page xxi.)

• Chapter 4, Developing Through the Life Span, has been shortened by moving the Aging and Intelligence coverage to Chapter 9, Thinking, Language, and Intelligence.

• NEW Chapter 5, Gender and Sexuality, includes new and significantly reorganized discussions.

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xviii PREFACE

• Chapter 6, Sensation and Perception, now covers both topics in a more efficient and integrated fashion (rather than covering sensation first, then perception). Coverage of the deaf experience is now in Chapter 9, Thinking, Language, and Intelligence.

• Chapter 7, Learning, now has a separate Biology, Cognition, and Learning section that more fully explores the biological and cognitive constraints on learning.

• Chapter 8, Memory, follows a new format, and more clearly explains how differ- ent brain networks process and retain memories. I worked closely with Janie Wilson (Professor of Psychology at Georgia Southern University and Vice President for Pro- gramming of the Society for the Teaching of Psychology) in this chapter’s revision.

• Chapter 10 now combines Motivation with Emotion. • Chapter 11, Stress, Health, and Human Flourishing, now includes discussion of

positive psychology, well-being, and personal control.

• Chapter 12, Personality, offers improved coverage of modern-day psychodynamic approaches, which are now more clearly distinguished from their historical Freud- ian roots.

• The Social Psychology chapter now follows the Personality chapter. • Chapter 14, Psychological Disorders, now includes coverage of eating disorders,

previously in the Motivation chapter.

Clinical Chapters Were Carefully Reviewed and Signifi cantly Improved With helpful guidance from clinical psychologist colleagues, I have strengthened the clinical perspective, which has improved the Personality, Psychological Disorders,

and Therapy chapters, among others. For example, I cover problem- focused and emotion-focused coping strategies and the relationship of psychotherapy to cancer survival in the Stress, Health, and Human Flourishing chapter, and the Intelligence chapter describes how psychol- ogists use intelligence tests in clinical settings. Material from today’s positive psychology is also woven throughout (see TABLE 3).

In addition, the Personality and Therapy chapters now more clearly distinguish between historical psychoanalysis and modern-day psycho- dynamic theories.

New Time Management Section for Students To help students maximize their reading, studying, and exam prepara- tion efforts, a new student preface offers time management guidance.

Beautiful New Design and Contemporary New Photo Program This new, more open and colorful design, chock full of new photos and illustrations, provides a modern visual context for the book’s up-to- date coverage.

Dedicated Versions of Next-Generation Media This ninth edition is accompanied by the dramatically enhanced Psych- Portal, which adds new features (LearningCurve formative assess- ment activities and Launch Pad carefully crafted prebuilt assignments) while incorporating the full range of Worth’s psychology media products (Video Tool Kit, PsychInvestigator, PsychSim). (For details, see p. xxv.)

TABLE 3 Examples of Positive Psychology

Coverage of positive psychology topics can be found in the following chapters: Topic Chapter Altruism/Compassion 4, 9, 12, 13, 15 Coping 11 Courage 13 Creativity 8, 12, 13 Emotional intelligence 9, 13 Empathy 4, 7, 11, 13, 15 Flow 10 Gratitude 10, 11, 13 Happiness/Life Satisfaction 4, 10, 11 Humility 13 Humor 11, 13 Justice 13 Leadership 10, 12, 13, App B Love 4, 5, 10, 11, 12, 13, 14, 15 Morality 4 Optimism 11, 12 Personal control 11 Resilience 4, 11, 13, 15 Self-discipline 4, 10, 12 Self-efficacy 11, 12 Self-esteem 10, 12 Spirituality 11, 13 Toughness (grit) 9, 10 Wisdom 3, 4, 9, 12, 13

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PREFACE xix

What Continues? Eight Guiding Principles Despite all the exciting changes, this new edition retains its predecessors’ voice, as well as much of the content and organization. It also retains the goals—the guiding principles—that have animated the previous eight editions:

Facilitating the Learning Experience 1. To teach critical thinking By presenting research as intellectual detective

work, I illustrate an inquiring, analytical mindset. Whether students are studying development, cognition, or social behavior, they will become involved in, and see the rewards of, critical reasoning. Moreover, they will discover how an empirical approach can help them evaluate competing ideas and claims for highly publicized phenomena—ranging from ESP and alternative therapies, to astrology and repressed and recovered memories.

2. To integrate principles and applications Throughout—by means of anec- dotes, case histories, and the posing of hypothetical situations—I relate the fi ndings of basic research to their applications and implications. Where psychology can illu- minate pressing human issues—be they racism and sexism, health and happiness, or violence and war—I have not hesitated to shine its light.

3. To reinforce learning at every step Everyday examples and rhetorical ques- tions encourage students to process the material actively. Concepts presented earlier are frequently applied, and reinforced, in later chapters. For instance, in Chapter 3, students learn that much of our information processing occurs outside of our con- scious awareness. Ensuing chapters drive home this concept. Numbered Learning Objective Questions at the beginning of each main section, Retrieve It self-tests throughout each chapter, a marginal glossary, and Chapter Review key terms lists and self-tests help students learn and retain important concepts and terminology.

Demonstrating the Science of Psychology 4. To exemplify the process of inquiry I strive to show students not just the out-

come of research, but how the research process works. Throughout, the book tries to excite the reader’s curiosity. It invites readers to imagine themselves as partici- pants in classic experiments. Several chapters introduce research stories as mysteries that progressively unravel as one clue after another falls into place.

5. To be as up-to-date as possible Few things dampen students’ interest as quickly as the sense that they are reading stale news. While retaining psychology’s classic studies and concepts, I also present the discipline’s most important recent developments. More than 900 references in this edition are dated 2009–2012. Like- wise, the new photos and everyday examples are drawn from today’s world.

6. To put facts in the service of concepts My intention is not to fi ll students’ intellectual fi le drawers with facts, but to reveal psychology’s major concepts—to teach students how to think, and to offer psychological ideas worth thinking about. In each chapter, I place emphasis on those concepts I hope students will carry with them long after they complete the course. Always, I try to follow Albert Einstein’s purported dictum that “everything should be made as simple as possible, but not simpler.” Learning Objective Questions and Retrieve It questions throughout each chapter help students focus on the most important concepts.

Promoting Big Ideas and Broadened Horizons 7. To enhance comprehension by providing continuity Many chapters

have a signifi cant issue or theme that links subtopics, forming a thread that ties the chapter together. The Learning chapter conveys the idea that bold

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xx PREFACE

thinkers can serve as intellectual pioneers. The Thinking, Language, and Intelli- gence chapter raises the issue of human rationality and irrationality. The Psycho- logical Disorders chapter conveys empathy for, and understanding of, troubled lives. Other threads, such as cognitive neuroscience, dual processing, and cultural and gender diversity, weave throughout the whole book, and students hear a consistent voice.

8. To convey respect for human unity and diversity Throughout the book, readers will see evidence of our human kinship—our shared biological heritage, our common mechanisms of seeing and learning, hungering and feeling, loving and hating. They will also better understand the dimensions of our diversity—our individual diversity in development and aptitudes, temperament and personality, and disorder and health; and our cultural diversity in attitudes and expressive styles, child-rearing and care for the elderly, and life priorities.

Continually Improving Cultural and Gender Diversity Coverage This edition presents an even more thoroughly cross-cultural perspective on psychology (TABLE 4)—ref lected in research findings and text and photo exam- ples. New Chapter 5, Gender and Sexuality, allows a separate-chapter focus on the psychology of women and men, though these topics are also thoroughly integrated throughout the text (see TABLE 5). In addition, I am working to offer a world-based psychology for our worldwide student readership. Thus, I continually search the world for research findings and text and photo examples, conscious that readers may be in Melbourne, Sheffield, Vancouver, or Nairobi. North American and European examples come easily, given that I reside in the United States, maintain contact with friends and colleagues in Canada, subscribe to several European periodicals, and live periodically in the U.K. This edition, for example, offers many dozens of Canadian, British, and Australian and New Zealand examples. We are all citizens of a shrink- ing world, thanks to increased migration and the growing global economy. Thus, American students, too, benefit from information and examples that international- ize their world-consciousness. And if psychology seeks to explain human behavior (not just American or Canadian or Australian behavior), the broader the scope of studies presented, the more accurate is our picture of this world’s people. My aim is to expose all students to the world beyond their own culture, and I continue to welcome input and suggestions from all readers. Discussion of the relevance of cultural and gender diversity begins on the first page of the first chapter and contin- ues throughout the text.

Strong Critical Thinking Coverage I aim to introduce students to critical thinking throughout the book. Revised Learning Objective Questions at the beginning of each main section, and Retrieve It questions throughout each chapter, encourage critical reading to glean an understanding of important concepts. This ninth edition also includes the following opportunities for students to learn or practice their critical think- ing skills.

• Chapter 1, Thinking Critically With Psychological Science, introduces students to psychology’s research methods, emphasizing the fallacies of our everyday intuition and common sense and, thus, the need for psychological science. Critical thinking is introduced as a key term in this chapter (p. 15). Appendix A, Statistical Reasoning in Everyday Life, encourages students to “focus on thinking smarter by applying simple statistical principles to everyday reasoning.”

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PREFACE xxi

TABLE 4 Culture and Multicultural Experience

Culture and multicultural experience is covered on the following pages:

TABLE 5 The Psychology of Men and Women

The psychology of men and women is covered on the following pages:

Absolute thresholds, pp. 193–194 ADHD, p. 607 Adulthood: physical changes, pp. 150–151 Aggression, pp. 481–483

father absence, p. 484 pornography, pp. 484–485 rape, pp. 484, 485

Alcohol: and addiction, p. 103 and sexual aggression, pp. 102–103 use, pp. 102–103

Altruism, pp. 493–494 Antisocial personality disorder,

pp. 538–539 Attraction, pp. 487–491 Autism, p. 140 Behavioral effects of gender, pp. 26–27 Biological predispositions in color

perceptions, p. 257 Biological sex/gender, pp. 167–168 Bipolar disorder, pp. 520–521 Body image, pp. 536–537 Color vision, pp. 206–208 Conformity/obedience, p. 467–470 Dating, p. 488 Depression, pp. 520, 521–522

learned helplessness, p. 526 Dream content, pp. 93–94 Drug use:

biological influences, p. 110

psychological/social-cultural influences, pp. 110–112

Eating disorders, pp. 536–537 Emotion-detecting ability, pp. 379–381,

381–382 Empty nest, p. 156 Father care, p. 135 Father presence, p. 177 Freud’s views:

evaluating, pp. 430–432 identification/gender identity,

pp. 426–427 Oedipus/Electra complexes, p. 426 penis envy, p. 428

Fundamental attribution error, pp. 458–459

Gender: and anxiety, p. 513 and child-rearing, pp. 170–171 development, p. 164 “missing women,” p. 477 prejudice, pp. 476–478 roles, pp. 169–170 similarities/differences, pp. 164–166

Gendered brain, pp. 167, 175, 182–183 Generic pronoun “he,” p. 327 Grief, pp. 157–158 Group polarization, p. 473 Happiness, pp. 417–418 Hearing loss, pp. 217–218, 322

Hormones and: aggression, p. 482 sexual behavior, pp. 171–172 sexual development, pp. 140–141, 167 testosterone-replacement therapy, p. 172

Intelligence: bias, p. 345 stereotype threat, pp. 345–346

Leadership: transformational, p. B12 Losing weight, p. 363 Love, pp. 154–156, 491–493 Marriage, p. 155, 405 Maturation, pp. 140–141 Menarche, p. 140 Menopause, p. 151 Midlife crisis, p. 154 Obesity:

genetic factors, pp. 361–362 health risks, p. 361

Observational learning: sexually violent media, p. 265 TV’s influence, pp. 263–264

Pain sensitivity, p. 221 Pornography, pp. 175–176 Prejudice, p. 306 Psychological disorders, rates of, p. 540 PTSD: development of, pp. 515–516 Rape, p. 481 Religiosity and life expectancy, pp. 410, 412 REM sleep, arousal in, p. 86

Romantic love, pp. 491–493 Savant syndrome, p. 331 Schizophrenia, p. 528 Self-injury, p. 525 Sense of smell, pp. 225–226 Sexual attraction, pp. 184–185 Sexual dysfunctions, pp. 173–174 Sexual fantasies, p. 176 Sexual orientation, pp. 178–173 Sexuality, pp. 175–176 Sexuality:

adolescent, pp. 176–178 evolutionary explanation, pp. 183–184 external stimuli, pp. 175–176 imagined stimuli, p. 176

Sexualization of girls, p. 177 Stereotyping, p. 198 Stress and:

AIDS, p. 396 depression, pp. 399–400 health, and sexual abuse, p. 407 heart disease, pp. 397–398 immune system, pp. 394–396 response to, pp. 392–394

Suicide, pp. 524–525 Teratogens: alcohol consumption, p. 120 Women in psychology’s history, p. 3

See also Chapter 5, Gender and Sexuality, and Chapter 13, Social Psychology.

Aggression, p. 484 and video games, pp. 265, 485–486

Aging population, pp. 151–152 AIDS, p. 396 Anger, pp. 398–399 Animal research ethics, pp. 27–28 Attraction: love and marriage,

pp. 492–493 Attractiveness, pp. 184–185, 490 Attribution: political effects of, p. 459 Behavioral effects of culture, pp. 26–27,

67–68 Body ideal, pp. 536–537 Body image, pp. 536–537 Categorization, p. 306 Conformity, pp. 465, 467 Corporal punishment practices, pp. 251–252 Cultural norms, pp. 164, 464 Culture:

context effects, pp. 198–199 definition, p. 463 variation over time, p. 464

Culture and the self, pp. 450–451 Culture shock, p. 391 Deaf culture, pp. 58, 61, 320, 321–322 Development:

adolescence, p. 140 attachment, p. 137 child-rearing, pp. 138–139 cognitive development, p. 129 moral development, pp. 142–143 parenting styles, pp. 138–139 social development, pp. 132–133

Drug use, p. 112 Emotion:

emotion-detecting ability, pp. 379–381 Emotion: expressing, pp. 381–382,

383–385 Enemy perceptions, p. 498 Fear, p. 310–311 Flow, p. B1 Fundamental attribution error, p. 458 Gender:

cultural norms, pp. 164, 169 roles, p. 169–170 social power, p. 165

Grief, expressing, pp. 157–158 Happiness, pp. 416–418 Hindsight bias, pp. 11–12 History of psychology, pp. 2–5 Homosexuality, views on, p. 178 Human diversity/kinship, pp. 26–27,

463–464 Identity: forming social, pp. 144–145 Individualism/collectivism, p. 451 Intelligence, pp. 329–330, 343, 344

bias, p. 345 Down syndrome, p. 338 nutrition and, p. 344

Language, pp. 319–321, 326–327, 464 critical periods, pp. 321–322 monolingual/bilingual, p. 327 universal grammar, p. 321

Leaving the nest, pp. 148–149 Life satisfaction, p. 415 Life span and well-being, pp. 156–157

Loop systems for hearing assistance, p. B14

Management styles, pp. B11–B13 Marriage, p. 155 Meditation, pp. 409–410 Memory, encoding, pp. 276–277 Menopause, p. 151 Mental illness rate, pp. 540–541 Motivating achievement, pp. B7–B8 Motivation: hierarchy of needs, p. 355 Need to belong, pp. 364–365 Neurotransmitters: curare, pp. 39–41 Obesity, pp. 361–362, 362–363 Observational learning: television and

aggression, p. 264 Organ donation, pp. 312–313 Pace of life, pp. 19, 464 Pain: perception of, pp. 220–225 Parent and peer relationships,

pp. 145–146 Participative management, pp. B11–B12 Peacemaking:

conciliation, p. 500 contact, p. 499 cooperation, pp. 499–500

Peer influence, pp. 145–147 Power of individuals, pp. 474–475 Prejudice, pp. 24, 29, 476–481

“missing women,” p. 477 Prejudice prototypes, p. 306 Psychological disorders:

cultural norms, p. 506 dissociative personality disorder, p. 534

eating disorders, pp. 508, 536–537 schizophrenia, pp. 508, 531–532 suicide, pp. 524–525 susto, p. 508 taijin-kyofusho, p. 508

Psychotherapy: culture and values in, pp. 566–567 EMDR training, p. 563

Puberty and adult independence, pp. 148–149

Self-esteem, p. 417 Self-serving bias, pp. 448–449 Sex drive, p. 184 Sexual orientation, pp. 178–183 Similarities, pp. 70–72 Sleep patterns, pp. 87–88 Social clock, p. 154 Social loafing, pp. 471–472 Social networking, pp. 367–368 Social-cultural perspective, pp. 7–11 Spirituality: Israeli kibbutz communities,

pp. 410–411 Stress:

adjusting to a new culture, p. 391 health consequences, p. 401 racism and, p. 392

Taste preferences, pp. 359–360 Teen sexuality, pp. 176–178 Testing bias, p. 345 Weight control, p. 360

See also Chapter 13, Social Psychology.

TT

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xxii PREFACE

• “Thinking Critically About . . .” boxes are found throughout the book, modeling for students a critical approach to some key issues in psychology. For example, see the updated box “Thinking Critically About: The Fear Factor—Why We Fear the Wrong Things” (pages 310–311).

• Detective-style stories throughout the narrative get students thinking critically about psychology’s key research questions. For example, in Chapter 14, I present the causes of schizophrenia piece by piece, showing students how researchers put the puzzle together.

• “Apply this” and “Think about it” style discussions keep students active in their study of each chapter. In Chapter 13, for example, students take the perspective of participants in a Solomon Asch conformity experiment, and later in one of Stanley Milgram’s obedience experiments. I’ve also asked students to join the fun by taking part in activities they can try along the way. For example, in Chapter 6, they try out a quick sensory adaptation activity. In Chapter 10, they try matching expres- sions to faces and test the effects of different facial expressions on themselves.

• Critical examinations of pop psychology spark interest and provide important les- sons in thinking critically about everyday topics. For example, Chapter 6 includes a close examination of ESP, and Chapter 8 addresses the controversial topic of repression of painful memories.

See TABLE 6 for a complete list of this text’s coverage of critical thinking topics and Thinking Critically About boxes.

TABLE 6 Critical Thinking and Research Emphasis

Critical thinking coverage, and in-depth stories of psychology’s scientific research process, can be found on the following pages:

Thinking Critically About . . . boxes: Addiction, p. 101 The Evolutionary Perspective on

Human Sexuality, pp. 183–186 Can Subliminal Messages Control Our

Behavior?, p. 195 ESP—Perception Without Sensation?,

pp. 230–232 Does Viewing Media Violence Trigger

Violent Behavior?, p. 265 The Fear Factor—Why We Fear the

Wrong Things, pp. 310–311 Lie Detection, p. 379 How to Be a “Successful” Astrologer

or Palm Reader, pp. 438–439 ADHD—Normal High Energy or

Genuine Disorder?, p. 507 Insanity and Responsibility, p. 512

Critical Examinations of Pop Psychology: The need for psychological science,

p. 10 Perceiving order in random events,

pp. 12–13 Do we use only 10 percent of our

brains?, p. 56 Can hypnosis enhance recall? Coerce

action? Be therapeutic? Alleviate pain?, pp. 97–98

Has the concept of “addiction” been stretched too far?, p. 101

Near-death experiences, p. 107 Critiquing the evolutionary perspec-

tive, pp. 185–186 How much credit or blame do parents

deserve?, p. 147 Sensory restriction, pp. 97–100 Is there extrasensory perception?,

pp. 230–232 Do other species exhibit language?,

pp. 323–325 How valid is the Rorschach test?,

pp. 429–430 Is repression a myth?, p. 431 Is Freud credible?, pp. 430–432 Is psychotherapy effective?,

pp. 560–563 Evaluating alternative therapies,

pp. 563–565 Do video games teach or release vio-

lence?, pp. 485–486

Thinking Critically With Psychological Science:

The limits of intuition and common sense, pp. 10–13

The scientific attitude, pp. 13–14

Critical thinking introduced as a key term, p. 15

The scientific method, pp. 15–17 Correlation and causation, pp. 21–22 Exploring cause and effect,

pp. 22–23 Random assignment, pp. 22–23 Independent and dependent variables,

pp. 23–24 Statistical reasoning, pp. A1–A4 Describing data, pp. A1–A4 Making inferences, pp. A7–A8

Scientific Detective Stories: Is breast milk better than formula?,

pp. 22–23 Our divided brains, pp. 59–61 Twin and adoption studies,

pp. 63–66 Why do we sleep?, pp. 88–89 Why do we dream?, pp. 94–96 Is hypnosis an extension of normal

consciousness or an altered state?, pp. 98–100

How a child’s mind develops, pp. 124–129

What determines sexual orientation?, pp. 178–183

Parallel processing, pp. 205–206 How do we see in color?, pp. 206–208 How are memories constructed?,

pp. 274–280 How do we store memories in our

brains?, pp. 280–282 Do other species exhibit language?,

pp. 323–325 Aging and intelligence, pp. 337–338 Why do we feel hunger?, pp. 357–359 Why—and in whom—does stress

contribute to heart disease?, pp. 397–399

How and why is social support linked with health?, pp. 405–407

The pursuit of happiness: Who is happy, and why?, pp. 412–419

Self-esteem versus self-serving bias, pp. 448–450

Why do people fail to help in emergen- cies?, pp. 494–495

What causes mood disorders?, pp. 521–527

Do prenatal viral infections increase risk of schizophrenia?, pp. 531–532

Is psychotherapy effective?, pp. 560–561

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PREFACE xxiii

APA Principles and New MCAT 2015 Guidelines APA Principles for Quality Undergraduate Education and APA Learning Goals and Outcomes In February 2011, the American Psychological Association (APA) approved the new Principles for Quality Undergraduate Education in Psychology. These broad-based prin- ciples and their associated recommendations were designed to “produce psychologi- cally literate citizens who apply the principles of psychological science at work and at home.” (See www.apa.org/education/undergrad/principles.aspx.)

APA’s more specif ic 2002 Learning Goals and Outcomes (from their Guidelines for the Undergraduate Psychology Major, updated in 2006) were designed to gauge progress in students graduating with psychology majors. (See www.apa.org/ed/ precollege/about/psymajor-guidelines.pdf ) Many psychology departments have since used these goals and outcomes to help establish their own benchmarks for departmental assessment purposes. APA’s 2009 Assessment CyberGuide for Learn- ing Goals and Outcomes (www.apa.org/ed/governance/bea/assess.aspx) may assist your efforts.

Some instructors are eager to know whether a given text for the introductory course helps students get a good start at achieving these APA benchmarks. See www.worthpublishers.com/myers for detailed guides to how well Exploring Psychol- ogy, ninth edition, corresponds to both the 2011 APA Principles and the 2006 APA Learning Goals and Outcomes.

MCAT Will Include Psychology Starting in 2015 Beginning in 2015, the Medical College Admission Test (MCAT) is devoting 25 percent of its questions to the “Psychological, Social, and Biological Foundations of Behavior,” with most of those questions coming from the psychological science taught in introductory psychology courses. From 1977 to 2014, the MCAT focused on biology, chemistry, and physics. Hereafter, reports the new Preview Guide for MCAT 2015, the exam will also recognize “the importance of socio-cultural and behavioral determinants of health and health outcomes.” The exam’s new psychol- ogy section covers the breadth of topics in this text. See, for example, TABLE 7, which outlines the precise correlation between the topics in this text’s Sensation and Perception chapter and the corresponding portion of the MCAT exam. For a complete pairing of the new MCAT psychology topics with this book’s contents, see www.worthpublishers.com/myers.

TABLE 7 Sample MCAT Correlation With Exploring Psychology, Ninth Edition

MCAT 2015: Categories in Sensation and Perception Myers, Exploring Psychology, Ninth Edition, Correlations

Content Category 6e: Sensing the environment Section Title or Topic Page Number

Sensory Processing Sensation and Perception 191–235

Sensation Sensation and Perception 193–195

Thresholds Thresholds 193–195

Signal detection theory Signal detection theory 193

Sensory adaptation Sensory adaptation 196–197

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xxiv PREFACE

Sample MCAT Correlation With Exploring Psychology, Ninth Edition, continued

MCAT 2015: Categories in Sensation and Perception Myers, Exploring Psychology, Ninth Edition, Correlations

Content Category 6e: Sensing the environment Section Title or Topic Page Number

Sensory receptors transduce stimulus energy and transmit signals to the central nervous system.

Transduction 192

Sensory pathways Visual Information Processing 202–206

The Ear 216–217

Understanding Pain 221

Taste 224–225

Smell 225–226

Body Position and Movement 227

Types of sensory receptors The Eye 201–204

The Ear 216–219

Understanding Pain 221–222

Taste 224–225

Smell 225–226

Body Position and Movement 227

The cerebral cortex controls voluntary movement and cognitive functions.

Functions of the Cortex 54–57

Information processing in the cerebral cortex The Cerebral Cortex 53–57

Lateralization of cortical functions The Cerebral Cortex 53–56

Our Divided Brain 59–61

Right-Left Differences in the Intact Brain 61–62

Vision Vision 200–215

Structure and function of the eye The Eye 200–202

Visual processing Visual Information Processing 202–206

Visual pathways in the brain Figure 6.16 Pathway from the eyes to the visual cortex

203

Parallel processing Parallel processing 205–206

Feature detection Feature detection 204–205

Hearing Hearing 216–219

Auditory processing Transduction of sound 216–217

Auditory pathways in the brain Transduction of sound 216–217

Perceiving loudness and pitch Perceiving Loudness 218

Perceiving Pitch 219

Locating sounds Locating Sounds 219

Sensory reception by hair cells Photo of hair cells; detailed drawing of inner ear, including hair cells

216, 217

The Ear 216

Other Senses The Other Senses 220–227

Somatosensation

Sensory systems in the skin Sensory cortex 54–55

Touch 220

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PREFACE xxv

Next-Generation Multimedia Exploring Psychology, ninth edition, boasts impressive multimedia options. For more information about any of these choices, visit Worth Publishers’ online catalog at www.worthpublishers.com.

PsychPortal With LearningCurve Quizzing The ninth edition’s dramatically enhanced PsychPortal adds new features (Learn- ingCurve formative assessment activities and Launch Pad carefully crafted prebuilt assignments) while incorporating the full range of Worth’s psychology media options (Video Tool Kit, PsychInvestigator, PsychSim).

Based on the latest f indings from learning and memory research, LearningCurve combines adaptive question selection, personalized study plans, immediate and valuable feedback, and state-of-the-art question analysis reports. LearningCurve’s game-like nature keeps students engaged while helping them learn and remember key concepts.

Sample MCAT Correlation With Exploring Psychology, Ninth Edition, continued

MCAT 2015: Categories in Sensation and Perception Myers, Exploring Psychology, Ninth Edition, Correlations

Content Category 6e: Sensing the environment Section Title or Topic Page Number

Tactile pathways in the brain Sensory cortex 54–55

Figure 6.38 The pain circuit 221

Types of pain Pain 221–222

Factors that infl uence pain Biological Infl uences 221–222

Psychological Infl uences 222

Social-Cultural Infl uences 222–223

Taste Taste 224–225

Taste buds/chemoreceptors that detect specifi c chemicals in the environment

Taste receptors and their functions 224–225

Gustatory pathways in the brain Processing taste in the brain 226

Smell Smell 225–227

Olfactory cells/chemoreceptors that detect specifi c chemicals in the environment

Olfactory receptor cells, and processing olfaction in the brain

225–226

Pheromones Smell of sex-related hormones 181, 182

Olfactory pathways in the brain Processing olfaction in the brain 225–226

Role of smell in perception of taste Sensory Interaction 227–229

Perception Sensation and Perception 191–235

Bottom-up/Top-down processing Bottom-up and top-down processing 192, 221

Perceptual organization (i.e., depth, form, motion, constancy) Visual Organization: Form Perception, Depth Perception (including Relative Motion), Perceptual Constancy

208–214

Processing motion 205

Gestalt principles Gestalt principles 208–209

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xxvi PREFACE

Launch Pad offers a set of prebuilt assignments, carefully crafted by a group of instructional designers and instructors with an abundance of teaching experience as well as deep familiarity with Worth content. Each Launch Pad unit contains videos, activities, and formative assessment pieces to build student understanding for each topic, culminating with a randomized summative quiz to hold students accountable for the unit. Assign units in just a few clicks, and find scores in your gradebook upon submission. Launch Pad appeals not only to instructors who have been interested in adding an online component to their course but haven’t been able to invest the time, but also to experienced online instructors curious to see how other colleagues might scaffold a series of online activities. Customize units as you wish, adding and drop- ping content to fit your course. (See FIGURE 2.)

Faculty Support and Student Resources • New! Faculty Lounge—http://psych.facultylounge.worthpublishers.com—(see

FIGURE 3) is an online place to find and share favorite teaching ideas and materials, including videos, animations, images, PowerPoint® slides and lectures, news stories, articles, web links, and lecture activities. Includes publisher- as well as peer-provided resources—all faculty-reviewed for accuracy and quality.

• Instructor’s Media Guide for Introductory Psychology • Enhanced Course Management Solutions (including course cartridges) • eBook in various available formats, with embedded Concepts in Action • Book Companion Site

FIGURE 2 Launch Pad in PsychPortal

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PREFACE xxvii

Video and Presentation • New! Worth Introductory Psychology Videos, produced in conjunction with

Scientific American and Nature, is a breakthrough collection of NEW modular, tutorial videos on core psychology topics. This set includes animations, interviews with top scientists, and carefully selected archival footage and is available on flash drive, or as part of the new Worth Video Anthology for Introductory Psychology.

• New! The Worth Video Anthology for Introductory Psychology is a com- plete collection, all in one place, of our video clips from the Video Tool Kit, the Digital Media Archive, and the third edition of the Scientific American Frontiers Teaching Modules, as well as from the new Worth Introductory Psychology Videos co-produced with Scientific American and Nature. Available on DVD or flash drive, the set is accompanied by its own Faculty Guide.

• New! Interactive Presentation Slides for Introductory Psychology is an extraordinary series of PowerPoint® lectures . This is a dynamic, yet easy-to-use new way to engage students during classroom presentations of core psychology topics. This collection provides opportunities for discussion and interaction, and includes an unprecedented number of embedded video clips and animations (including activities from our ActivePsych series).

Assessment • New! LearningCurve • Printed Test Banks • Diploma Computerized Test Banks • Online Quizzing • i•clicker Radio Frequency Classroom Response System

FIGURE 3 Sample from our Faculty Lounge site (psych.facultylounge.worthpublishers.com)

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xxviii PREFACE

Print • Instructor’s Resources • Lecture Guides • Study Guide • Pursuing Human Strengths: A Positive Psychology Guide • Critical Thinking Companion, Second Edition • Psychology and the Real World: Essays Illustrating Fundamental Contributions to Society.

This ©2011 project of the FABBS Foundation brought together a virtual “Who’s Who” of contemporary psychological scientists to describe—in clear, captivating ways—the research they have passionately pursued and what it means to the “real world.” Each contribution is an original essay written for this project.

From Scientifi c American • Improving the Mind & Brain: A Scientific American Special Issue • Scientific American Reader to Accompany Myers

In Appreciation If it is true that “whoever walks with the wise becomes wise” then I am wiser for all the wisdom and advice received from my colleagues. Aided by thousands of consul- tants and reviewers over the last two decades, this has become a better, more accurate book than one author alone (this author, at least) could write. As my editors and I keep reminding ourselves, all of us together are smarter than any one of us.

My indebtedness continues to each of the teacher-scholars whose inf luence I acknowledged in the eight previous editions, to the innumerable researchers who have been so willing to share their time and talent to help me accurately report their research, and to the 1155 instructors and students who took the time to offer feed- back over the phone, in a survey, or at one of our face-to-face focus groups. I also appreciated having detailed consultation on the Memory chapter from Janie Wilson (Georgia Southern University, and Vice President for Programming of the Society of the Teaching of Psychology).

Nathan DeWall (University of Kentucky) offered valuable input as a special contributor for this edition. He assisted with the revision of the Need to Belong section in Chapter 10, Motivation and Emotion; the Personal Control discussion in Chapter 11, Stress, Health, and Human Flourishing; and the Aggression discussion in Chapter 13, Social Psychology.

Amy Himsel (El Camino College), a gifted teacher with a keen ability to connect with students, guided creation of the self-test study aids found throughout this new edition.

My gratitude extends to the colleagues who contributed criticism, corrections, and creative ideas related to the content, pedagogy, and format of this new edition and its teaching package. For their expertise and encouragement, and the gifts of their time to the teaching of psychology, I thank the reviewers and consultants listed here.

Jennifer Adler, Borough of Manhattan Community College, CUNY

David Alfano, Community College of Rhode Island

Leslie Cramblet Alvarez, Adams State College

Willow Aureala, Hawaii Community College

Rosiana Azman, Kapiolani Community College

Debra Bacon, Bristol Community College— Fall River Campus

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PREFACE xxix

Robert Baker, Sandhills Community College

Meeta Banerjee, Michigan State University

Carol Batt, Seattle Central Community College

Kiersten Baughman, University of Oklahoma

Alexander Beaujean, Baylor University

Karen Bekker, Bergen Community College

Anjan Bhattacharyya, New Jersey City University

Beth Bigler, Pellissippi State Tech Community College

Melissa Birkett, Northern Arizona University

Tim Boffeli, Clarke University

Gregory Bolich, Belmont Abbey College

Pamela Bradley, Sandhills Community College

Jennifer Breneiser, Valdosta State University

Gayle Brosnan-Watters, Chandler Gilbert Community College

Cheryl Carmichael, Brooklyn College, CUNY

Ana Carmona, Austin Peay State University

Natalie Ceballos, Texas State University—San Marcos

Kelly Charlton, University of North Carolina at Pembroke

Barbara Chutroo, Borough of Manhattan Community College, CUNY

Pamela Costa, Tacoma Community College

Baine Craft, Seattle Pacifi c University

Christy Cummings, Community College of Denver

Drew Curtis, Texas Woman’s University

Robert Dale, Butler University

Deborah Dalke, Defi ance College

Robert Daniel, Bridgewater State College

Mary Fran Davis, Austin Peay State University

Sarah D’Elia, George Mason University

Meliksah Demir, Northern Arizona University

Jean Desto, Anna Maria College

Wendy Domjan, University of Texas—Austin

Evelyn Doody, College of Southern Nevada

Kathryn Dumper, Bainbridge College

Robert Egbert, Walla Walla University

Julie Ehrhardt, Bristol Community College—New Bedford

Daniella Errett, Penn Highlands Community College

Kim Felsenthal, Berkeley College

Christopher Ferguson, Texas A&M International University

Bill Flack, Bucknell University

Jonathan Forbey, Ball State University

Claire Ford, Bridgewater State University

William Fry, Youngstown State University

Crystal Gabert-Quillen, Kent State University

Dennis Galvan, Gallaudet University

Karen Gee-Atwood, Foothill College

Inna Ghajoyan, California State University—Northridge

Jennifer Gibson, Tarleton State University

Amanda Gingerich, Butler University

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xxx PREFACE

Wind Goodfriend, Buena Vista University

Dan Grangaard, Austin Community College

Melinda Green, Cornell College

Kelly Hagan, Bluegrass Community & Technical College

Diane Hall, Bay Path College

Pamela Hall, Barry University

Stephen Hampe, Utica College

Rhiannon Hart, Rochester Institute of Technology

Wendy Hart, Arizona State University

Myra Harville, Holmes Community College

Matthew Hayes, Winthrop University

Carmon Hicks, Ivy Tech Community College

Kathleen Hipp, Daniel Webster College

Brian Hock, Austin Peay State University

Lori Hokerson, American River College

Mia Holland, Bridgewater State College

Gary Homann, Lincoln University of Missouri

Mildred Huffman, Jefferson College of Health Sciences

Steven Isonio, Golden West College

Lora Jacobi, Stephen F. Austin State University

Jenny Jellison, Waynesburg College

Barry Johnson, Davidson County Community College

Peter Karl Jonason, University of West Florida

Diana Joy, Community College of Denver

Stephen Joy, Albertus Magnus College

Tracy Juliao, University of Michigan—Dearborn Campus

Deana Julka, University of Portland

Bethany Jurs, University of Wisconsin—Stout Campus

Diane Kappen, Johnson County Community College

Katrina Kardiasmenos, Bowie State University

Chithra KarunaKaran, Borough of Manhattan Community College, CUNY

Brent King, Adams State College

Teresa King, Bridgewater State College

Annette Kluck, Auburn University

Franz Klutschkowski, North Central Texas College

Dana Kuehn, Florida State College at Jacksonville

Carol LaLiberte, Asnuntuck Community College

Donna Landon-Jimenez, Caldwell College, Mount Saint Mary Academy

Cynthia Lausberg, Pittsburg University

Melissa Lea, Millsaps University

Fred Leavitt, California State University—Hayward

Heather Lench, Texas A&M University

Nicolette Lopez, University of Texas at Arlington

Ken Luke, Tyler Junior College

Melanie Maggard, Mount San Jacinto College

Toby Marx, Union County College

Jim Matiya, Florida Gulf Coast University

Simone Matlock-Phillips, Bay Path College

Elizabeth Matys-Rahbar, Greenwich High School

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PREFACE xxxi

Tammy McClain, West Liberty University

Daniel McConnell, University of Central Florida

Kyla McKay-Dewald, Bristol Community College— Fall River Campus

Thomas Meriweather, Virginia Military Institute

Nadia Monosov, California State University—Northridge

James Moore, Marshall University

Robin Musselman, Lehigh Carbon Community College

Michelle Mychajlowskyj, Quinnipiac University

Robert Newby, Tarleton State University

Arthur Olguin, Santa Barbara City College

Don Osborn, Bellarmine College

Neophytos Papaneophytou, Borough of Manhattan Community College, CUNY

Thomas Peterson, Grand View University

Zehra Peynircioglu, American University

Kellie Pierson, Northern Kentucky University

Gary Popoli, Stevenson University

Jack Powell, University of Hartford

Patrick Progar, Caldwell College

Michael Rader, Johnson County Community College

Kimberly Renk, University of Central Florida

Shannon Scott Rich, Texas Woman’s University

Cynthia Rickert, Ivy Tech Community College

Hugh H. Riley, Baylor University

Kristin Ritchey, Ball State University

Clarence Rohrbaugh, Fairmont State College James Rollins, Austin Peay State University Jane Russell, Austin Peay State University Valerie Scott, Indiana University Southeast Neda Senehi, California State University—Northridge Tim Shearon, The College of Idaho LaTishia Smith, Ivy Tech Community College Rita Smith-Wade-El, Millersville University Kristin Sorensen, Defi ance College Gary Springer, Los Angeles College International Jonathan D. Springer, Kean University Kimberly Stark-Wroblewski, University of Central Missouri Meri Stiles, Lyndon State College Deborah Stipp, Ivy Tech Community College Dawn Strongin, California State University—Stanislaus Donna Stuber-McEwen, Friends University Robert Tanner, Albuquerque Technical Vocational Institute Yonca Toker, Georgia Institute of Technology Stephen Truhon, Austin Peay State University Lynda Vannice, Umpqua Community College Nancy Voorhees, Ivy Tech Community College Benjamin Wallace, Cleveland State University Thomas Westcott, University of West Florida Keilah Worth, St. Catherine University Frederic Wynn, County College of Morris

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xxxii PREFACE

At Worth Publishers a host of people played key roles in creating this ninth edition. Although the information gathering is never ending, the formal planning began

as the author-publisher team gathered for a two-day retreat in June 2010. This happy and creative gathering included John Brink, Thomas Ludwig, Richard Straub, and me from the author team, along with my assistants Kathryn Brownson and Sara Neevel. We were joined by Worth Publishers executives Tom Scotty, Elizabeth Widdicombe, Catherine Woods, Craig Bleyer, and Mark Resmer; editors Chris- tine Brune, Kevin Feyen, Nancy Fleming, Tracey Kuehn, Betty Probert, and Trish Morgan; artistic director Babs Reingold; sales and marketing colleagues Tom Kling, Carlise Stembridge, John Britch, Lindsay Johnson, Cindi Weiss, Kari Ewalt, Mike Howard, and Matt Ours; and special guests Amy Himsel (El Camino Community College), Jennifer Peluso (Florida Atlantic University), Charlotte vanOyen Witvliet (Hope College), and Jennifer Zwolinski (University of San Diego). The input and brainstorming during this meeting of minds gave birth, among other things, to the study aids in this edition, the carefully revised clinical coverage, the separate gender and sexuality chapter, and the refreshing new design.

Christine Brune, chief editor for the last eight editions, is a wonder worker. She offers just the right mix of encouragement, gentle admonition, attention to detail, and passion for excellence. An author could not ask for more.

Development editor Nancy Fleming is one of those rare editors who is gifted both at “thinking big” about a chapter—and with a kindred spirit to my own—while also applying her sensitive, graceful, line-by-line touches.

Publisher Kevin Feyen is a valued team leader, thanks to his dedication, creativity, and sensitivity. Catherine Woods (Senior Vice President, Editorial and Production) helped construct and execute the plan for this text and its supplements. Catherine was also a trusted sounding board as we faced a seemingly unending series of discrete decisions along the way. Elizabeth Block and Nadina Persaud coordinated produc- tion of the huge media and print supplements package for this edition. Betty Probert efficiently edited and produced the print supplements and, in the process, also helped fine-tune the whole book. Nadina also provided invaluable support in commission- ing and organizing the multitude of reviews, mailing information to professors, and handling numerous other daily tasks related to the book’s development and produc- tion. Lee Ann McKevitt did a splendid job of laying out each page. Bianca Moscatelli and Donna Ranieri worked together to locate the myriad photos.

Tracey Kuehn, Director of Print and Digital Development, displayed tire- less tenacity, commitment, and impressive organization in leading Worth’s gifted artistic production team and coordinating editorial input throughout the produc- tion process. Production Manager Sarah Segal masterfully kept the book to its tight schedule, and Art Director Babs Reingold skillfully directed creation of the beauti- ful new design and art program. Production Manager Stacey Alexander, along with Supplements Production Editor Edgar Bonilla, did their usual excellent work of producing the many supplements.

To achieve our goal of supporting the teaching of psychology, this teaching pack- age not only must be authored, reviewed, edited, and produced, but also made avail- able to teachers of psychology. For their exceptional success in doing that, our author team is grateful to Worth Publishers’ professional sales and marketing team. We are especially grateful to Executive Marketing Manager Kate Nurre, Marketing Manager Lindsay Johnson, and National Psychology and Economics Consultant Tom Kling both for their tireless efforts to inform our teaching colleagues of our efforts to assist their teaching, and for the joy of working with them.

At Hope College, the supporting team members for this edition included Kathryn Brownson, who researched countless bits of information and proofed hundreds of pages. Kathryn has become a knowledgeable and sensitive adviser on many matters, and Sara Neevel has become our high-tech manuscript developer, par excellence.

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PREFACE xxxiii

Again, I gratefully acknowledge the inf luence and editing assistance of my writing coach, poet Jack Ridl, whose inf luence resides in the voice you will be hearing in the pages that follow. He, more than anyone, cultivated my delight in dancing with the language, and taught me to approach writing as a craft that shades into art.

After hearing countless dozens of people say that this book’s supplements have taken their teaching to a new level, I ref lect on how fortunate I am to be a part of a team in which everyone has produced on-time work marked by the highest profes- sional standards. For their remarkable talents, their long-term dedication, and their friendship, I thank John Brink, Thomas Ludwig, and Richard Straub, and I welcome Jennifer Peluso (Florida Atlantic University) to our teaching package team. I am grateful for Jenny’s excellent work—building on the many years of creative effort contributed by the late Martin Bolt.

Finally, my gratitude extends to the many students and instructors who have writ- ten to offer suggestions, or just an encouraging word. It is for them, and those about to begin their study of psychology, that I have done my best to introduce the field I love.

The day this book went to press was the day I started gathering information and ideas for the tenth edition. Your input will again inf luence how this book continues to evolve. So, please, do share your thoughts.

Hope College Holland, Michigan 49422-9000 USA davidmyers.org

www.tinyurl.com/MeetDavidMyers

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TIME MANAGEMENT: OR, HOW TO BE A GREAT STUDENT AND

STILL HAVE A LIFE

xxxiv

We all face challenges in our schedules. Some of you may be taking midnight courses, others squeezing in an online course in between jobs or after putting chil- dren to bed at night. Some of you may be veterans using military benefits to jump- start a new life.

How can you balance all of your life’s demands and be successful? Time manage- ment. Manage the time you have so that you can find the time you need.

In this section, I will outline a simple, four-step process for improving the way you make use of your time.

1. Keep a time-use diary to understand how you are using your time. You may be surprised at how much time you’re wasting.

2. Design a new schedule for using your time more effectively.

3. Make the most of your study time so that your new schedule will work for you.

4. If necessary, refi ne your new schedule, based on what you’ve learned.

How Are You Using Your Time Now? Although everyone gets 24 hours in the day and seven days in the week, we fill those hours and days with different obligations and interests. If you are like most people, you probably use your time wisely in some ways, and not so wisely in others. Answering the questions in TABLE 1 can help you find trouble spots—and hopefully more time for the things that matter most to you.

The next thing you need to know is how you actually spend your time. To find out, record your activities in a time-use diary for one week. Be realistic. Take notes on

—Richard O. Straub University of Michigan, Dearborn

© N

ic k

Pa rk

asHow Are You Using Your Time Now?

Design a Better Schedule Plan the Term

Plan Your Week

CLOSE-UP: More Tips for Effective Scheduling

Make Every Minute of Your Study Time Count Take Useful Class Notes

Create a Study Space That Helps You Learn

Set Specifi c, Realistic Daily Goals

Use SQ3R to Help You Master This Text

Don’t Forget About Rewards!

Do You Need to Revise Your New Schedule? Are You Doing Well in Some Courses But Not in Others?

Have You Received a Poor Grade on a Test?

Are You Trying to Study Regularly for the First Time and Feeling Overwhelmed?

Motivated students: This course at Bunker Hill Community College meets at the increasingly popular time of midnight to 2:00 A.M., allowing shift workers, busy parents, and others to make it to class.

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how much time you spend attending class, studying, working, commut- ing, meeting personal and family needs, f ixing and eating meals, social- izing (don’t forget texting, Facebooking, and gaming), exercising, and anything else that occupies your time, including life’s small practical tasks, which can take up plenty of your 24/7. As you record your activi- ties, take notes on how you are feeling at various times of the day. When does your energy slump, and when do you feel most energetic?

Design a Better Schedule Take a good look at your time-use diary. Where do you think you may be wasting time? Do you spend a lot of time commuting, for example? If so, could you use that time more productively? If you take public transportation, commuting is a great time to read and test yourself for review.

Did you remember to include time for meals, personal care, work sched- ules, family commitments, and other fixed activities?

How much time do you sleep? In the battle to meet all of life’s daily commitments and interests, we tend to treat sleep as optional. Do your best to manage your life so that you can get enough sleep to feel rested. You will feel better and be healthier, and you will also do better academically and in relationships with your family and friends. (You will read more about this in Chapter 3.)

Are you dedicating enough time for focused study? Take a last look at your notes to see if any other patterns pop out. Now it’s time to create a new and more efficient schedule.

Plan the Term Before you draw up your new schedule, think ahead. Buy a portable calendar that covers the entire school term, with a writing space for each day. Using the course outlines provided by your instructors, enter the dates of all exams, term-paper deadlines, and other important assign- ments. Also be sure to enter your own long-range personal plans (work and family commitments, etc.). Carry this calendar with you each day. Keep it up-to-date, refer to it often, and change it as needed. Through this process, you will develop a regular schedule that will help you achieve success.

Plan Your Week To pass those exams, meet those deadlines, and keep up with your life outside of class, you will need to convert your long-term goals into a daily schedule. Be realistic—you will be living with this routine for the entire school term. Here are some more things to add to that portable calendar.

1. Enter your class times, work hours, and any other fi xed obligations. Be thorough. Allow plenty of time for such things as commuting, meals, and laundry.

2. Set up a study schedule for each course. Remember what you learned about yourself in the study habits survey (Table 1) and your time-use diary. Close-Up: More Tips for Effective Scheduling (next page) offers some detailed guidance drawn from psy- chology’s research.

3. After you have budgeted time for studying, fi ll in slots for other obligations, exer- cise, fun, and relaxation.

TIME MANAGEMENT xxxv

Table 1 Study Habits Survey

Answer the following questions, writing Yes or No for each line.

1. Do you usually set up a schedule to budget your time for studying, work, recreation, and other activities?

2. Do you often put off studying until time pres- sures force you to cram?

3. Do other students seem to study less than you do, but get better grades?

4. Do you usually spend hours at a time study- ing one subject, rather than dividing that time among several subjects?

5. Do you often have trouble remember- ing what you have just read in a textbook?

6. Before reading a chapter in a textbook, do you skim through it and read the section headings?

7. Do you try to predict test questions from your class notes and reading?

8. Do you usually try to summarize in your own words what you have just finished reading?

9. Do you find it difficult to concentrate for very long when you study?

10. Do you often feel that you studied the wrong material for a test?

Thousands of students have participated in similar surveys. Students who are fully realizing their aca- demic potential usually respond as follows: (1) yes, (2) no, (3) no, (4) no, (5) no, (6) yes, (7) yes, (8) yes, (9) no, (10) no.

Do your responses fit that pattern? If not, you could benefit from improving your time management and study habits.

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xxxvi TIME MANAGEMENT

Make Every Minute of Your Study Time Count How do you study from a textbook? Many students simply read and reread in a passive manner. As a result, they remember the wrong things—the catchy stories but not the main points that show up later in test questions. To make things worse, many students take poor notes during class. Here are some tips that will help you get the most from your class and your text.

Take Useful Class Notes Good notes will boost your understanding and retention. Are yours thorough? Do they form a sensible outline of each lecture? If not, you may need to make some changes.

Keep Each Course’s Notes Separate and Organized Keeping all your notes for a course in one location will allow you to f lip back and forth easily to find answers to questions. Three options are (1) separate note- books for each course, (2) clearly marked sections in a shared ring binder, or (3) carefully organized folders if you opt to take notes electronically. For the print options, removable pages will allow you to add new information and weed out past mistakes. Choosing notebook pages with lots of space, or using mark-up options in electronic f iles, will allow you to add comments when you review and revise your notes after class.

Use an Outline Format Use roman numerals for major points, letters for supporting arguments, and so on. (See FIGURE 1 for a sample.) In some courses, taking notes will be easy, but some instructors may be less organized, and you will have to work harder to form your outline.

More Tips for Effective Scheduling

class. Increase your study time slowly by setting weekly goals that will gradually bring you up to the desired level.

Create a schedule that makes sense. Tailor your schedule to meet the demands of each course. For the course that emphasizes lecture notes, plan a daily review of your notes soon after each class. If you are evalu- ated for class participation (for example, in a language course), allow time for a review just before the class meets. Schedule study time for your most difficult (or least motivating) courses during hours when you are the most alert and distractions are fewest.

Schedule open study time. Life can be unpredictable. Emergencies and new obligations can throw off your schedule. Or you may simply need some extra time for a project or for review in one of your courses. Try to allow for some flexibility in your schedule each week.

Following these guidelines will help you find a schedule that works for you!

There are a few other things you will want to keep in mind when you set up your schedule.

Spaced study is more effective than massed study. If you need 3 hours to study one subject, for example, it’s best to divide that into shorter periods spaced over several days.

Alternate subjects, but avoid interference. Alternating the subjects you study in any given session will keep you fresh and will, surprisingly, increase your ability to remember what you’re learning in each different area. Studying similar topics back-to-back, however, such as two differ- ent foreign languages, could lead to interference in your learning. (You will hear more about this in Chapter 8.)

Determine the amount of study time you need to do well in each course. The time you need depends upon the difficulty of your courses and the effectiveness of your study methods. Ideally, you would spend at least 1 to 2 hours studying for each hour spent in

M Ti f

CLOSE UP

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TIME MANAGEMENT xxxvii

Clean Up Your Notes After Class Try to reorganize your notes soon after class. Expand or clarify your comments and clean up any hard-to-read scribbles while the material is fresh in your mind. Write impor- tant questions in the margin, or by using an electronic markup feature, next to notes that answer them. (For example: “What are the sleep stages?”) This will help you when you review your notes before a test.

Create a Study Space That Helps You Learn It’s easier to study effectively if your work area is well designed.

Organize Your Space Work at a desk or table, not in your bed or a comfy chair that will tempt you to nap.

Minimize Distractions Turn the TV off, turn off your phone, and close Facebook and other distracting windows on your computer. If you must listen to music to mask outside noise, play soft instrumentals, not vocal selections that will draw your mind to the lyrics.

Ask Others to Honor Your Quiet Time Tell roommates, family, and friends about your new schedule. Try to find a study place where you are least likely to be disturbed.

Set Specifi c, Realistic Daily Goals The simple note “7–8 P.M.: Study Psychology” is too broad to be useful. Instead, break your studying into manageable tasks. For example, you will want to subdivide large reading assignments. If you aren’t used to studying for long periods, start with relatively short periods of concentrated study, with breaks in between. In this text, for example, you might decide to read one major section before each break. Limit your breaks to 5 or 10 minutes to stretch or move around a bit.

Your attention span is a good indicator of whether you are pacing yourself successfully. At this early stage, it’s important to remember that you’re in training. If your attention begins to wander, get up immediately and take a short break. It is better to study effec- tively for 15 minutes and then take a break than to fritter away 45 minutes out of your study hour. As your endurance develops, you can increase the length of study periods.

Use SQ3R to Help You Master This Text David Myers organized this text by using a system called SQ3R (Survey, Question, Read, Retrieve, Review). Using SQ3R can help you to understand what you read, and to retain that information longer.

Sleep (Chapter 3) I. Biological Rhythms

A. Circadian Rhythm (circa-about; diem-day)—24-hour cycle.

B. FOUR Sleep Stages, cycle through every 90 minutes all

night! Aserinsky discovered—his son—REM sleep (dreams,

rapid eye movement, muscles paralyzed but brain super

active). EEG measurements showed sleep stages.

1. Ups and downs throughout day/night.

Dip in afternoon (siesta time).

2. Melatonin—hormone that makes us sleepy. Produced by pineal

gland in brain. Bright light shuts down production of melatonin.

(Dim the lights at night to get sleepy.)

When is my daily peak in circadian arousal? Study

hardest subject then!

1. NREM-1 (non-Rapid Eye Movement sleep; brief, images like

hallucinations; hypnagogic jerks)

2. NREM-2 (harder to waken, sleep spindles)

3. NREM-3 (DEEP sleep—hard to wake up! Long slow waves on EEG;

bedwetting, night terrors, sleepwalking occurs here; asleep but

not dead—can still hear, smell, etc. Will wake up for baby.)

4. REM Sleep (Dreams…)

FIGURE 1

Sample class notes in outline

form Here is a sample from a student’s notes taken in outline form from a lecture on sleep.

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xxxviii TIME MANAGEMENT

Applying SQ3R may feel at first as though it’s taking more time and effort to “read” a chapter, but with practice, these steps will become automatic.

Survey Before you read a chapter, survey its key parts. Scan the chapter outline. Note that main sections have numbered Learning Objective Questions to help you focus. Pay attention to headings, which indicate important subtopics, and to words set in bold type.

Surveying gives you the big picture of a chapter’s content and organization. Understanding the chapter’s logical sections will help you break your work into manageable pieces in your study sessions.

Question As you survey, don’t limit yourself to the numbered Learning Objective Questions that appear throughout the chapter. Jotting down additional questions of your own will cause you to look at the material in a new way. (You might, for example, scan this section’s headings and ask “What does ‘SQ3R’ mean?”) Information becomes easier to remember when you make it personally meaningful. Trying to answer your questions while reading will keep you in an active learning mode.

Read As you read, keep your questions in mind and actively search for the answers. If you come to material that seems to answer an important question that you haven’t jotted down, stop and write down that new question.

Be sure to read everything. Don’t skip photo or art captions, graphs, boxes, tables, or quotes. An idea that seems vague when you read about it may become clear when you see it in a graph or table. Keep in mind that instructors sometimes base their test questions on figures and tables.

Retrieve When you have found the answer to one of your questions, close your eyes and mentally recite the question and its answer. Then write the answer next to the question in your own words. Trying to explain something in your own words will help you f igure out where there are gaps in your understanding. These kinds of opportunities to practice retrieving develop the skills you will need when you are taking exams. If you study without ever putting your book and notes aside, you may develop false confidence about what you know. With the material available, you may be able to recognize the correct answer to your questions. But will you be able to recall it later, when you take an exam without having your mental props in sight?

Test your understanding as often as you can. Testing yourself is part of successful learning, because the act of testing forces your brain to work at remembering, thus establishing the memory more permanently (so you can find it later for the exam!). Use the self-testing opportunities throughout each chapter, including the periodic Retrieve It items. Also take advantage of the self-testing that is available on the free book companion website (www.worthpublishers.com/myers).

Review After working your way through the chapter, read over your questions and your written answers. Take an extra few minutes to create a brief written summary cover- ing all of your questions and answers. At the end of the chapter, you should take advantage of three important opportunities for self-testing and review—a list of the chapter’s Learning Objective Questions for you to try answering before checking

You will hear more about SQ3R in Chapter 1.

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TIME MANAGEMENT xxxix

Appendix D (Complete Chapter Reviews), a list of the chapter’s key terms for you to try to define before checking the referenced page, and a final self-test that covers all of the key chapter concepts (with answers in Appendix E).

Don’t Forget About Rewards! If you have trouble studying regularly, giving yourself a reward may help. What kind of reward works best? That depends on what you enjoy. You might start by making a list of 5 or 10 things that put a smile on your face. Spending time with a loved one, taking a walk or going for a bike ride, relaxing with a magazine or novel, or watching a favorite show can provide immediate rewards for achieving short-term study goals.

To motivate yourself when you’re having trouble sticking to your schedule, allow yourself an immediate reward for completing a specific task. If running makes you smile, change your shoes, grab a friend, and head out the door! You deserve a reward for a job well done.

Do You Need to Revise Your New Schedule? What if you’ve lived with your schedule for a few weeks, but you aren’t making progress toward your academic and personal goals? What if your studying hasn’t paid off in better grades? Don’t despair and abandon your program, but do take a little time to figure out what’s gone wrong.

Are You Doing Well in Some Courses But Not in Others? Perhaps you need to shift your priorities a bit. You may need to allow more study time for Chemistry, for example, and less time for some other course.

Have You Received a Poor Grade on a Test? Did your grade fail to ref lect the effort you spent preparing for the test? This can happen to even the hardest-working student, often on a first test with a new instruc- tor. This common experience can be upsetting. “What do I have to do to get an A?” “The test was unfair!” “I studied the wrong material!”

Try to figure out what went wrong. Analyze the questions you missed, dividing them into two categories: class-based questions and text-based questions. How many questions did you miss in each category? If you find far more errors in one category than in the other, you’ll have some clues to help you revise your schedule. Depending on the pattern you’ve found, you can add extra study time to review of class notes, or to studying the text.

Are You Trying to Study Regularly for the First Time and Feeling Overwhelmed? Perhaps you’ve set your initial goals too high. Remember, the point of time manage- ment is to identify a regular schedule that will help you achieve success. Like any skill, time management takes practice. Accept your limitations and revise your schedule to work slowly up to where you know you need to be—perhaps adding 15 minutes of study time per day.

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xl TIME MANAGEMENT

* * * I hope that these suggestions help make you more successful academically, and that they enhance the quality of your life in general. Having the necessary skills makes any job a lot easier and more pleasant. Let me repeat my warning not to attempt to make too dras- tic a change in your lifestyle immediately. Good habits require time and self-discipline to develop. Once established, they can last a lifetime.

REVIEW

Time Management: Or, How to Be a Great Student and Still Have a Life 1. How Are You Using Your Time Now?

• Identify your areas of weakness. • Keep a time-use diary. • Record the time you actually spend on activities. • Record your energy levels to fi nd your most productive times.

2. Design a Better Schedule

• Decide on your goals for the term and for each week. • Enter class times, work times, social times (for family and friends), and time needed for other obligations and for practical activities. • Tailor study times to avoid interference and to meet each course’s needs.

3. Make Every Minute of Your Study Time Count

• Take careful class notes (in outline form) that will help you recall and rehearse material covered in lectures. • Try to eliminate distractions to your study time, and ask friends and family to help you focus on your work. • Set specifi c, realistic daily goals to help you focus on each day’s tasks. • Use the SQ3R system (survey, question, read, retrieve, review) to master material covered in your text. • When you achieve your daily goals, reward yourself with something that you value.

4. Do You Need to Revise Your New Schedule?

• Allocate extra study time for courses that are more diffi cult, and a little less time for courses that are easy for you. • Study your test results to help determine a more effective balance in your schedule. • Make sure your schedule is not too ambitious. Gradually establish a schedule that will be effective for the long term.

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Exploring PSYCHOLOGY

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WHAT IS PSYCHOLOGY? Psychology’s Roots

CONTEMPORARY PSYCHOLOGY Psychology’s Biggest Question

Psychology’s Three Main Levels of Analysis

Psychology’s Subfields

THE NEED FOR PSYCHOLOGICAL SCIENCE What About Intuition and Common Sense?

The Scientific Attitude: Curious, Skeptical, and Humble

Critical Thinking

HOW DO PSYCHOLOGISTS ASK AND ANSWER QUESTIONS? The Scientific Method

Description

Correlation

Experimentation

FREQUENTLY ASKED QUESTIONS ABOUT PSYCHOLOGY

IMPROVE YOUR RETENTION—AND YOUR GRADES

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Hoping to satisfy their curiosity about people and to remedy their own woes, millions turn to “psychology.” They listen to talk-radio counseling. They read articles on psychic powers. They attend stop-smoking hypnosis semi- nars. They immerse themselves in self-help websites and books on the meaning of dreams, the path to ecstatic love, and the roots of personal happiness.

Others, intrigued by claims of psychological truth, wonder: Do mothers and infants bond in the first hours after birth? How—and how much—does parenting shape children’s per- sonalities and abilities? What factors affect our drive to achieve? Does psychotherapy heal?

In working with such questions, how can we separate uninformed opinions from examined conclusions? How can we best use psychology to understand why people think, feel, and act as they do?

Thinking Critically With Psychological Science

CHAPTERR1

1

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2 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

What Is Psychology? For people whose exposure to psychology comes from popular books, magazines, TV, and the Internet, psychologists seem to analyze personality, offer counseling, and dis- pense child - rearing advice. Do they? Yes, and much more. Consider some of psychol- ogy’s questions, which perhaps have also been yours:

• Have you ever found yourself reacting to something as one of your biological par- ents would—perhaps in a way you vowed you never would—and then wondered how much of your person ality you inherited? To what extent do genes predispose our person - to - person personality differences? To what extent do home and community environ- ments shape us?

• Have you ever worried about how to act among people of a different culture, race, gender, or sexual orientation? In what ways are we alike as members of the human fam- ily? How do we differ?

• Have you ever awakened from a nightmare and, with a wave of relief, wondered why you had such a crazy dream? How often, and why, do we dream?

• Have you ever played peekaboo with a 6-month - old and wondered why the baby finds the game so delightful? The infant reacts as though, when you momentarily move behind a door, you actually disappear—only to reappear out of thin air. What do babies actually perceive and think?

• Have you ever wondered what fosters school and work success? Are some people just born smarter? And does sheer intelligence explain why some people get richer, think more cre- atively, or relate more sensitively?

• Have you ever wondered how the Internet, video games, and electronic social net- works affect people? How do today’s electronic media influence how we think and how we relate?

• Have you ever become depressed or anxious and wondered whether you’ll ever feel “normal”? What triggers our bad moods—and our good ones? What’s the line between a normal mood swing and a psychological disorder for which someone should seek help?

Psychology is a science that seeks to answer such questions.

Psychology’s Roots

1-1: What are some important milestones in psychology’s development?

To be human is to be curious about ourselves and the world around us. Before 300 B.C.E., the Greek naturalist and philosopher Aristotle theorized about learning and memory, motivation and emotion, perception and personality. Today we chuckle at some of his guesses, like his suggestion that the source of our personality is the heart. But credit Aristotle with asking the right questions.

Psychological Science Is Born Philosophers’ thinking about thinking continued until the birth of psychology on a December day in 1879, in a small, third-floor room at Germany’s University of Leipzig. There, two young men were helping an austere, middle - aged professor, Wilhelm Wundt, create an experimental apparatus. Their machine measured the time lag between people’s hearing a ball hit a platform and their pressing a telegraph key (Hunt, 1993). Curiously, people responded in about one - tenth of a second when asked to press the key as soon as the sound occurred—and in about two - tenths of a second when asked to press the key as soon as they were consciously aware of perceiving the sound. (To be aware of one’s awareness takes a little longer.) Wundt was seeking to measure “atoms of

A smile is a smile the world around Throughout this book, you will see examples not only of our cultural and gender diversity but also of the similarities that define our shared human nature. People in different cultures vary in when and how often they smile, but a naturally happy smile means the same thing anywhere in the world.

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To assist your active learning of psychology, Learning Objectives, framed as questions, appear at the beginning of major sections. You can test your understanding by trying to answer the question before, and then again after, you read the section.

Information sources are cited in parentheses, with name and date. Every citation can be found in the end- of-book References, with complete documentation that follows American Psychological Association style.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 3

the mind”—the fastest and simplest mental processes. So began the first psychological laboratory, staffed by Wundt and by psychology’s first graduate students.

Before long, this new science of psychology became organized into different branches, or schools of thought, each promoted by pioneering thinkers. Two early schools were structuralism and functionalism. As physicists and chemists discerned the structure of matter, so Wundt’s student Edward Bradford Titchener aimed to discover the mind’s structure. He engaged people in self-reflective introspection (looking inward), training them to report elements of their experience as they looked at a rose, listened to a metronome, smelled a scent, or tasted a substance. What were their immediate sensations, their images, their feelings? And how did these relate to one another? Alas, introspection proved some- what unreliable. It required smart, verbal people, and its results varied from person to per- son and experience to experience. As introspection waned, so did structuralism.

Hoping to assemble the mind’s structure from simple elements was rather like try- ing to understand a car by examining its disconnected parts. Philosopher-psychologist William James thought it would be more fruitful to consider the evolved functions of our thoughts and feelings. Smelling is what the nose does; thinking is what the brain does. But why do the nose and brain do these things? Under the influence of evolu- tionary theorist Charles Darwin, James assumed that thinking, like smelling, developed because it was adaptive—it contributed to our ancestors’ survival. Consciousness serves a function. It enables us to consider our past, adjust to our present, and plan our future. As a functionalist, James encouraged explorations of down-to-earth emotions, memories, willpower, habits, and moment-to-moment streams of consciousness.

As these names illustrate, the early pioneers of most fields, including psychology, were predominantly men. In 1890, over the objections of Harvard’s president, James admitted Mary Whiton Calkins into his graduate seminar (Scarborough & Furumoto, 1987). (In those years women lacked even the right to vote.) When Calkins joined, the other students (all men) dropped out. So James tutored her alone. Later, she finished all of Harvard’s Ph.D. requirements, outscoring all the male students on the qualifying exams. Alas, Harvard denied her the degree she had earned, offering her instead a degree from Radcliffe College, its undergraduate “sister” school for women. Calkins resisted the unequal treatment and refused the degree. She nevertheless went on to become a distinguished memory researcher and the American Psychological Association’s (APA’s) first female president in 1905.

The honor of being the first female psychology Ph.D. later fell to Margaret Floy Washburn, who also wrote an influential book, The Animal Mind, and became the APA’s second female president in 1921.

Wilhelm Wundt Wundt established the first psychology laboratory at the University of Leipzig, Germany. © Bettmann/Corbis

William James and Mary Whiton Calkins James was a legendary teacher - writer who authored an important 1890 psychology text. He mentored Calkins, who became a pioneering memory researcher and the first woman to be president of the American Psychological Association. (left) Mary Evans Picture Library/Alamy; (right) Wellesley College Archives

Margaret Floy Washburn The first woman to receive a psychology Ph.D., Washburn synthesized animal behavior research in The Animal Mind. Center for the History of Psychology Archives of the History of American Psychology, The University of Akron

structuralism early school of thought pro- moted by Wundt and Titchener; used introspec- tion to reveal the structure of the human mind.

functionalism early school of thought promoted by James and influenced by Darwin; explored how mental and behavioral processes function—how they enable the organism to adapt, survive, and flourish.

Throughout the text, important concepts are boldfaced. As you study, you can find these terms with their definitions in a nearby margin and in the Glossary at the end of the book.

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4 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

RETRIEVE IT

• What event defined the start of scientific psychology?

ANSWER: Scientific psychology began in Germany in 1879 when Wilhelm Wundt opened the first psychology laboratory.

• Why did introspection fail as a method for understanding how the mind works?

• used introspection to define the mind’s makeup;

focused on how mental processes enable us to adapt, survive, and flourish.

Psychological Science Develops In the field’s early days, many psychologists shared with the English essayist C. S. Lewis the view that “there is one thing, and only one in the whole universe which we know more about than we could learn from external observation.” That one thing, Lewis said, is ourselves: “We have, so to speak, inside information” (1960, pp. 18–19). Wundt and Titchener focused on inner sensations, images, and feelings. James engaged in introspec- tive examination of the stream of consciousness and emotion. For these and other early pioneers, psychology was defined as “the science of mental life.”

And so it continued until the 1920s, when the first of two provocative American psychologists appeared on the scene. John B. Watson, and later B. F. Skinner, dismissed introspection and redefined psychology as “the scientific study of observable behavior.” You cannot observe a sensation, a feeling, or a thought, they said, but you can observe and record people’s behavior as they respond to different situations. Many agreed, and the behaviorists became one of psychology’s two major forces well into the 1960s.

The other major force was Freudian psychology, which emphasized the ways our uncon- scious thought processes and our emotional responses to childhood experiences affect our behavior. (In chapters to come, we’ll look more closely at Sigmund Freud’s ideas.)

As the behaviorists had rejected the early 1900s definition of psychology, two other groups rejected the behaviorist definition in the 1960s. The first, the humanistic psychologists, led by Carl Rogers and Abraham Maslow, found both Freudian psychol- ogy and behaviorism too limiting. Rather than focusing on the meaning of early child- hood memories or on the learning of conditioned responses, the humanistic psychologists drew attention to ways that current environmental influences can nurture or limit our growth potential, and the importance of having our needs for love and acceptance satisfied. (More on this in Chapter 12.)

The second group of psychologists pioneered the 1960s cogni- tive revolution, leading the field back to its early interest in

mental processes. Cognitive psychology scientifically explores how we perceive, process, and remember information,

and even why we can get anxious or depressed. Cog- nitive neuroscience, an interdisciplinary study, has enriched our understanding of the brain activity underlying mental activity.

To encompass psychology’s concern with observable behavior and with inner thoughts and feelings, today we define psychology as the science of behavior and mental processes. Let’s unpack this definition. Behavior is anything

an organism does—any action we can observe and record. Yelling, smiling, blinking, sweating, talking, and question-

naire marking are all observable behaviors. Mental processes are the internal, subjective experiences we infer from behavior—

sensations, perceptions, dreams, thoughts, beliefs, and feelings.

John B. Watson and Rosalie Rayner Working with Rayner, Watson cham- pioned psychology as the science of behavior and demonstrated conditioned responses on a baby who became famous as “Little Albert.” (More about Watson’s controversial study in Chapter 7.) (left) ©Underwood & Underwood/Corbis (right) Center for the History of Psychology Archives of the History of American Psychology, The University of Akron

Study Tip: Memory research reveals a testing effect: We retain information much better if we actively retrieve it by self-testing and rehearsing. To bolster your learning and memory, take advantage of the Retrieve It opportunities you’ll find throughout this text. ANSWER: People’s self-reports varied, depending on the experience and the person’s intelligence and verbal ability.

ANSWER: Structuralism; functionalism

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 5

behaviorism the view that psychology (1) should be an objective science that (2) studies behavior without reference to mental processes. Most research psychologists today agree with (1) but not with (2).

humanistic psychology historically sig- nificant perspective that emphasized the growth potential of healthy people.

cognitive neuroscience the interdis- ciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).

psychology the science of behavior and mental processes.

nature– nurture issue the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors. Today’s psychological science sees traits and behaviors arising from the interaction of nature and nurture.

The key word in psychology’s definition is science. Psychology is less a set of find- ings than a way of asking and answering questions. My aim, then, is not merely to report results but also to show you how psychologists play their game. You will see how researchers evaluate conflicting opinions and ideas. And you will learn how all of us, whether scientists or simply curious people, can think smarter when describing and explaining the events of our lives.

RETRIEVE IT

• How did the cognitive revolution affect the field of psychology?

ANSWER: It recaptured the field’s early interest in mental processes and made them legitimate topics for scientific study.

Contemporary Psychology This young science of psychology developed from the more established fields of phi- losophy and biology. Wundt was both a philosopher and a physiologist. Ivan Pavlov, who pioneered the study of learning (Chapter 7), was a Russian physiologist. Freud was an Austrian physician. Jean Piaget, the last century’s most influential observer of children, (Chapter 4), was a Swiss biologist. James was an American philosopher. This list of pio- neering psychologists—“Magellans of the mind,” as Morton Hunt (1993) has called them—illustrates psychology’s origins in many disciplines and countries.

Like the pioneers, today’s psychologists are citizens of many lands. The International Union of Psychological Science has 71 member nations, from Albania to Zimbabwe. Psychology is growing and it is globalizing. The story of psychology is being written in many places, with interests ranging from nerve cell activity to international conflicts.

Psychology’s Biggest Question

1-2: What is psychology’s historic big issue?

Are our human traits present at birth, or do they develop through experience? The debate over this huge nature–nurture issue is ancient. The Greek phi-

losopher Plato (428–348 B.C.E.) assumed that we inherit character and intelligence and that certain ideas are inborn. Aristotle (384–322 B.C.E.) countered that there is nothing in the mind that does not first come in from the external world through the senses.

B. F. Skinner A leading behaviorist, Skinner rejected introspection and studied how conse- quences shape behavior. Bachrach/Getty Images

Sigmund Freud The controversial ideas of this famed personality theorist and therapist have influenced humanity’s self-understanding. © Bettmann/Corbis

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6 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

More insight into nature’s influ- ence on behavior arose after a 22-year-old seafaring voyager, Charles Darwin, pondered the incredible species variation he encountered, including tortoises on one island that differed from those on nearby islands. His 1859 On the Origin of Species explained this diver- sity by proposing the evolutionary process of natural selection: From among chance variations, nature selects traits that best enable an

organism to survive and reproduce in a particular environment. Darwin’s principle of natural selection is still with us 150+ years later as biology’s organizing principle, and now an important principle for twenty-first-century psychology. This would surely have pleased Darwin, for he believed his theory explained not only animal structures (such as a polar bear’s white coat) but also animal behaviors (such as the emotional expressions associated with human lust and rage).

The nature –nurture issue recurs throughout this text as today’s psychologists explore the relative contributions of biology and experience, asking, for example, how we humans are alike (because of our common biology and evolutionary history) and diverse (because of our differing environments). Are gender differences biologically predisposed or socially constructed? Is children’s grammar mostly innate or formed by experience? How are intelligence and personality differences influenced by heredity, and by envi- ronment? Are sexual behaviors more “pushed” by inner biology or “pulled” by external incentives? Should we treat psychological disorders—depression, for example—as disor- ders of the brain, disorders of thought, or both?

Over and over again we will see that in contemporary science the nature – nurture tension dissolves: Nurture works on what nature endows. Our species is biologically endowed with an enormous capacity to learn and adapt. Moreover, every psychological event (every thought, every emotion) is simultaneously a biological event. Thus, depression can be both a brain disorder and a thought disorder.

RETRIEVE IT

• What is contemporary psychology’s position on the nature–nurture debate?

ANSWER: Psychological events often stem from the interaction of nature and nurture, rather than from either of them acting alone.

Psychology’s Three Main Levels of Analysis

1-3: What are psychology’s levels of analysis and related perspectives?

Each of us is a complex system that is part of a larger social system. But each of us is also composed of smaller systems, such as our nervous system and body organs, which are composed of still smaller systems—cells, molecules, and atoms.

These tiered systems suggest different levels of analysis, which offer complemen- tary outlooks. It’s like explaining why grizzly bears hibernate. Is it because hibernation helped their ancestors to survive and reproduce? Because their inner physiology drives them to do so? Because cold environments hinder food gathering during winter? Such perspectives are complementary because “everything is related to everything else” (Brewer, 1996). Together, different levels of analysis form a bio psycho social approach, which integrates biological, psychological, and social-cultural factors (FIGURE 1.1).

A nature-made nature–nurture experiment Because identical twins have the same genes, they are ideal participants in studies designed to shed light on hereditary and environ- mental influences on intelligence, personality, and other traits. Studies of identical and fraternal twins provide a rich array of findings—described in later chapters—that underscore the importance of both nature and nurture. (left) © Hola Images/agefotostock; (right) WoodyStock /Alamy

natural selection the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations.

levels of analysis the differing comple- mentary views, from biological to psychologi- cal to social-cultural, for analyzing any given phenomenon.

biopsychosocial approach an inte- grated approach that incorporates biological, psychological, and social-cultural levels of analysis.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 7

Each level provides a vantage point for viewing a behavior or mental process, yet each by itself is incomplete. Like different academic disciplines, psychology’s varied perspectives ask different questions and have their own limits. The different perspectives described in TABLE 1.1 complement one another. Consider, for example, how they shed light on anger:

• Someone working from a neuroscience perspective might study brain circuits that cause us to be “red in the face” and “hot under the collar.”

• Someone working from the evolutionary perspective might analyze how anger facili- tated the survival of our ancestors’ genes.

• Someone working from the behavior genetics perspective might study how heredity and experience influence our individual differences in temperament.

• Someone working from the psychodynamic perspective might view an outburst as an outlet for unconscious hostility.

Psychological influences: • learned fears and other learned expectations • emotional responses • cognitive processing and perceptual interpretations

Biological influences: • natural selection of adaptive traits • genetic predispositions responding to environment • brain mechanisms • hormonal influences

Social-cultural influences: • presence of others • cultural, societal, and family expectations • peer and other group influences • compelling models (such as in the media)

Behavior or mental process

Table 1.1

Psychology’s Current Perspectives

Perspective Focus Sample Questions

Neuroscience How the body and brain enable emotions, memories, and sensory experiences

How do pain messages travel from the hand to the brain? How is blood chemistry linked with moods and motives?

Evolutionary How the natural selection of traits has promoted the survival of genes

How does evolution influence behavior tendencies?

Behavior genetics How our genes and our environment influence our individual differences

To what extent are psychological traits such as intelligence, personality, sexual ori- entation, and vulnerability to depression products of our genes? Of our environment?

Psychodynamic How behavior springs from unconscious drives and conflicts

How can someone’s personality traits and disorders be explained by unfulfilled wishes and childhood traumas?

Behavioral How we learn observable responses How do we learn to fear particular objects or situations? What is the most effective

way to alter our behavior, say, to lose weight or stop smoking?

Cognitive How we encode, process, store, and retrieve information

How do we use information in remembering? Reasoning? Solving problems?

Social - cultural How behavior and thinking vary across situations and cultures

How are we alike as members of one human family? How do we differ as products of our environment?

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Biopsychosocial approach This integrated viewpoint incorporates various levels of analysis and offers a more complete picture of any given behavior or mental process.

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8 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

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“I’m a social scientist, Michael. That means I can’t explain electricity or anything like that, but if you ever want to know about people I’m your man.”

Psychology in court Forensic psycholo- gists apply psychology’s principles and meth- ods in the criminal justice system. They may assess witness credibility, or testify in court on a defendant’s state of mind and future risk.

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• Someone working from the behavioral perspective might attempt to determine which external stimuli trigger angry responses or aggressive acts.

• Someone working from the cognitive perspective might study how our interpretation of a situation affects our anger and how our anger affects our thinking.

• Someone working from the social - cultural perspective might explore how expressions of anger vary across cultural contexts.

The point to remember: Like two-dimensional views of a three-dimensional object, each of psychology’s perspectives is helpful. But each by itself fails to reveal the whole picture.

RETRIEVE IT

• What advantage do we gain by using the biopsychosocial approach in studying psychological events?

ANSWER: By incorporating different levels of analysis, the biopsychosocial approach can provide a more complete view than any one perspective could offer.

Psychology’s Subfields

1-4: What are psychology’s main subfields?

Picturing a chemist at work, you probably envision a white - coated scientist surrounded by glassware and high - tech equipment. Picture a psychologist at

work and you would be right to envision

• a white - coated scientist probing a rat’s brain. • an intelligence researcher measuring how quickly an infant shows boredom by

looking away from a familiar picture.

• an executive evaluating a new “healthy life styles” training program for employees. • someone at a computer analyzing data on whether adopted teens’ temperaments

more closely resemble those of their adoptive parents or their biological parents.

• a therapist listening carefully to a client’s depressed thoughts. • a traveler visiting another culture and collecting data on variations in human values

and behaviors.

• a teacher or writer sharing the joy of psychology with others.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 9

The cluster of subfields we call psychology is a meeting ground for different dis- ciplines. Thus, it’s a perfect home for those with wide -ranging interests. In its diverse activities, from biological experimentation to cultural comparisons, psychology is united by a common quest: describing and explaining behavior and the mind underlying it.

Some psychologists conduct basic research that builds psychology’s knowledge base. In the pages that follow we will meet a wide variety of such researchers, including bio- logical psychologists exploring the links between brain and mind; developmental psychologists studying our changing abilities from womb to tomb; cognitive psychologists experimenting with how we perceive, think, and solve problems; personality psychologists investigating our persistent traits; and social psychologists exploring how we view and affect one another.

These and other psychologists also may conduct applied research, tackling practi- cal problems. Industrial-organizational psychologists, for example, use psychology’s concepts and methods in the workplace to help organizations and companies select and train employees, boost morale and productivity, design products, and implement systems.

Although most psychology textbooks focus on psychological science, psychology is also a helping profession devoted to such practical issues as how to have a happy marriage, how to overcome anxiety or depression, and how to raise thriving children. As a science, psychology at its best bases such interventions on evidence of effectiveness. Counseling psychologists help people to cope with challenges and crises (including academic, vocational, and marital issues) and to improve their personal and social func- tioning. Clinical psychologists assess and treat mental, emotional, and behavior disor- ders. Both counseling and clinical psychologists administer and interpret tests, provide counseling and therapy, and sometimes conduct basic and applied research. By contrast, psychiatrists, who also may provide psychotherapy, are medical doctors licensed to prescribe drugs and otherwise treat physical causes of psychological disorders.

To balance historic psychology’s focus on human problems, Martin Seligman and others (2002, 2005, 2011) have called for more research on human strengths and human flourishing. Their positive psychology scientifically explores “positive emotions, positive character traits, and enabling institutions.” What, they ask, can psychology contribute to a “good life” that engages one’s skills, and to a “meaningful life” that points beyond oneself?

With perspectives ranging from the biological to the social, and with settings from the laboratory to the clinic, psychology relates to many fields. Psychologists teach not only in psychology departments, but also in medical schools, law schools, and theologi- cal seminaries, and they work in hospitals, factories, and corporate offices. They engage in interdisciplinary studies, such as psychohistory (the psychological analysis of historical characters), psycholinguistics (the study of language and thinking), and psychoceramics (the study of crackpots).1

1 Confession: I wrote the last part of this sentence on April Fools’ Day.

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Psychology: A science and a profession Psychologists experiment with, observe, test, and treat behavior. Here we see psychologists testing a child, measuring emotion- related physiology, and doing face - to - face therapy.

basic research pure science that aims to increase the scientific knowledge base.

applied research scientific study that aims to solve practical problems.

counseling psychology a branch of psychology that assists people with problems in living (often related to school, work, or rela- tionships) and in achieving greater well-being.

clinical psychology a branch of psychol- ogy that studies, assesses, and treats people with psychological disorders.

psychiatry a branch of medicine dealing with psychological disorders; practiced by physicians who sometimes provide medical (for example, drug) treatments as well as psycho- logical therapy.

positive psychology the scientific study of human functioning, with the goals of discov- ering and promoting strengths and virtues that help individuals and communities to thrive.

Want to learn more? See Appendix C, Subfields of Psychology, at the end of this book, and go to the regularly updated Careers in Psychology at www.yourpsychportal.com/myers to learn about the many interesting options available to those with bachelor’s, master’s, and doctoral degrees in psychology.

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10 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

The limits of intuition Personnel inter- viewers tend to be overconfident of their gut feelings about job applicants. Their confidence stems partly from their recalling cases where their favorable impression proved right, and partly from their ignorance about rejected applicants who succeeded elsewhere.

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“Those who trust in their own wits are fools.”

Proverbs 28:26

Psychology also influences culture. And psychology deepens our appreciation for how we humans perceive, think, feel, and act. By so doing it can indeed enrich our lives and enlarge our vision. Through this book I hope to help guide you toward that end. As educator Charles Eliot said a century ago: “Books are the quietest and most constant of friends, and the most patient of teachers.”

RETRIEVE IT

• Match the specialty on the left with the description on the right.

1. Clinical psychology a. Helps people cope with educational and life challenges.

2. Psychiatry b. Studies, assesses, and treats people with psychological disorders but usually does not provide medical therapy.

3. Counseling psychology c. Branch of medicine dealing with psychological disorders.

ANSWERS: 1. b, 2. c, 3. a

The Need for Psychological Science Although in some ways we outsmart the smartest computers, our intuition often goes awry. To err is human. Enter psychological science. With its procedures for gathering and sifting evidence, science restrains error. As we familiarize ourselves with its strategies and incorporate its underlying principles into our daily thinking, we can think smarter. Psychologists use the science of behavior and mental processes to better understand why people think, feel, and act as they do.

What About Intuition and Common Sense?

1-5: How do hindsight bias, overconfidence, and the tendency to perceive order in random events illustrate why science-based answers are more valid than those based on intuition and common sense?

Some people suppose that psychology merely documents and dresses in jargon what people already know: “So what else is new—you get paid for using fancy methods to prove what my grandmother knew?” Others place their faith in human intuition. Former President George W. Bush described the feeling to journalist Bob Woodward (2002) in explaining his decision to launch the Iraq war: “I’m a gut player. I rely on my instincts.” Today’s psychological science does document a vast intuitive mind. As we will see, our thinking, memory, and attitudes operate on two levels—conscious and uncon- scious—with the larger part operating off-screen, automatically. Like jumbo jets, we fly mostly on autopilot.

So, are we smart to listen to the whispers of our inner wisdom, to simply trust “the force within”? Or should we more often be subjecting our intuitive hunches to skepti- cal scrutiny?

This much seems certain: We often underestimate intuition’s perils. My geographical intuition tells me that Reno is east of Los Angeles, that Rome is south of New York, that Atlanta is east of Detroit. But I am wrong, wrong, and wrong. As novelist Madeleine L’Engle observed, “The naked intellect is an extraordinarily inaccurate instrument” (1973). Three phenomena—hindsight bias, judgmental overconfidence, and our tendency to perceive patterns in random events—illustrate why we cannot rely solely on intuition and common sense.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 11

Did We Know It All Along? Hindsight Bias Consider how easy it is to draw the bull’s eye after the arrow strikes. After the stock market drops, people say it was “due for a correction.” After the football game, we credit the coach if a “gutsy play” wins the game, and fault the coach for the “stupid play” if it doesn’t. After a war or an election, its outcome usually seems obvious. Although history may therefore seem like a series of inevitable events, the actual future is seldom foreseen. No one’s diary recorded, “Today the Hundred Years War began.”

This hindsight bias (also known as the I-knew-it-all-along phenomenon) is easy to demonstrate: Give half the members of a group some purported psychological finding, and give the other half an opposite result. Tell the first group, “Psychologists have found that separation weakens romantic attraction. As the saying goes, ‘Out of sight, out of mind.’” Ask them to imagine why this might be true. Most people can, and nearly all will then view this true finding as unsurprising.

Tell the second group the opposite: “Psychologists have found that separation strengthens romantic attraction. As the saying goes, ‘Absence makes the heart grow fonder.’” People given this untrue result can also easily imagine it, and most will also see it as unsurprising. When two opposite findings both seem like common sense, there is a problem.

Such errors in our recollections and explanations show why we need psychological research. Just asking people how and why they felt or acted as they did can sometimes be misleading—not because common sense is usually wrong, but because common sense more easily describes what has happened than what will happen.

Nevertheless, Grandma’s intuition is often right. As Yogi Berra once said, “You can observe a lot by watching.” (We have Berra to thank for other gems, such as “Nobody ever comes here—it’s too crowded,” and “If the people don’t want to come out to the ballpark, nobody’s gonna stop ’em.”) Because we’re all behavior watchers, it would be surprising if many of psychology’s findings had not been foreseen. Many people believe that love breeds happiness, and they are right (we have what Chapter 10 calls a deep “need to belong”). Indeed, as Daniel Gilbert, Brett Pelham, and Douglas Krull (2003) have noted, “good ideas in psychology usually have an oddly familiar quality, and the moment we encounter them we feel certain that we once came close to thinking the same thing ourselves and simply failed to write it down.” Good ideas are like good inventions; once created, they seem obvious. (Why did it take so long for someone to invent suitcases on wheels and Post-it Notes?)

Hindsight bias When drilling the Deep- water Horizon oil well in 2010, BP employees took some shortcuts and ignored some warning signs, without intending to put their company and the environment at serious risk. After the resulting Gulf oil spill, with the benefit of 20/20 hindsight, the foolishness of those judg- ments became obvious.

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Philosopher Søren Kierkegaard, 1813–1855

“Anything seems commonplace, once explained.”

Dr. Watson to Sherlock Holmes

hindsight bias the tendency to believe, after learning an outcome, that one would have foreseen it. (Also known as the I-knew - it - all - along phenomenon.)

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12 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

2 Boston is south of Paris. 3 The anagram solution: CHAOS.

Overconfidence in history:

“We don’t like their sound. Groups of guitars are on their way out.”

Decca Records, in turning down a recording contract with the Beatles

in 1962

“Computers in the future may weigh no more than 1.5 tons.”

Popular Mechanics, 1949

“They couldn’t hit an elephant at this distance.”

General John Sedgwick, just before being killed during a U.S. Civil War

battle, 1864

“The telephone may be appropriate for our American cousins, but not here, because we have an adequate supply of messenger boys.”

British expert group, evaluating the invention of the telephone

But sometimes Grandma’s intuition, informed by countless casual observations, has it wrong. In later chapters we will see how research has overturned popular ideas—that familiarity breeds contempt, that dreams predict the future, and that most of us use only 10 percent of our brain. We will also see how research has surprised us with discoveries about how the brain’s chemical messengers control our moods and memories, about other animals’ abilities, and about the effects of stress on our capacity to fight disease.

Overconfidence We humans tend to think we know more than we do. Asked how sure we are of our answers to factual questions (Is Boston north or south of Paris?), we tend to be more confi- dent than correct.2 Or consider these three anagrams, which Richard Goranson (1978) asked people to unscramble:

WREAT → WATER ETRYN → ENTRY GRABE → BARGE

About how many seconds do you think it would have taken you to unscramble each of these? Knowing the answers tends to make us overconfident—surely the solution would take only 10 seconds or so? In reality, the average problem solver spends 3 minutes, as you also might, given a similar anagram without the solution: OCHSA.3

Are we any better at predicting social behavior? Ohio State University psychologist Philip Tetlock (1998, 2005) collected more than 27,000 expert predictions of world events, such as the future of South Africa or whether Quebec would separate from Canada. His repeated finding: These predictions, which experts made with 80 percent confidence on average, were right less than 40 percent of the time. Nevertheless, even those who erred maintained their confidence by noting they were “almost right.” “The Québécois separatists almost won the secessionist referendum.”

RETRIEVE IT

• Why, after friends start dating, do we often feel that we knew they were meant to be together?

ANSWER: We often suffer from hindsight bias—after we’ve learned a situation’s outcome, that outcome seems familiar and therefore obvious.

Perceiving Order in Random Events In our natural eagerness to make sense of our world—what poet Wallace Stevens called our “rage for order”—we are prone to perceive patterns. People see a face on the moon, hear Satanic messages in music, or perceive the Virgin Mary’s image on a grilled cheese sandwich. Even in random data we often find order, because—here’s a curious fact of life—random sequences often don’t look random (Falk et al., 2009; Nickerson, 2002, 2005). In actual random sequences, patterns and streaks (such as repeating digits) occur more often than people expect (Oskarsson et al., 2009). To demonstrate this phenomenon for myself, I flipped a coin 51 times, with these results:

1. H 11. T 21. T 31. T 41. H 51. T 2. T 12. H 22. T 32. T 42. H 3. T 13. H 23. H 33. T 43. H 4. T 14. T 24. T 34. T 44. H 5. H 15. T 25. T 35. T 45. T 6. H 16. H 26. T 36. H 46. H 7. H 17. T 27. H 37. T 47. H 8. T 18. T 28. T 38. T 48. T 9. T 19. H 29. H 39. H 49. T 10. T 20. H 30. T 40. T 50. T

Maciej Oleksy /Shutterstock

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 13

Looking over the sequence, patterns jump out: Tosses 10 to 22 provided an almost per- fect pattern of pairs of tails followed by pairs of heads. On tosses 30 to 38 I had a “cold hand,” with only one head in nine tosses. But my fortunes immediately reversed with a “hot hand”—seven heads out of the next nine tosses. Similar streaks happen—about as often as one would expect in random sequences—in basketball shooting, baseball hitting, and mutual fund stock pickers’ selections (Gilovich et al., 1985; Malkiel, 2007; Myers, 2002). These sequences often don’t look random and so are overinterpreted. (“When you’re hot, you’re hot!”)

What explains these streaky patterns? Was I exercising some sort of paranormal con- trol over my coin? Did I snap out of my tails funk and get in a heads groove? No such explanations are needed, for these are the sorts of streaks found in any random data. Comparing each toss to the next, 23 of the 50 comparisons yielded a changed result— just the sort of near 50-50 result we expect from coin tossing. Despite seeming patterns, the outcome of one toss gives no clue to the outcome of the next.

However, some happenings seem so extraordinary that we struggle to conceive an ordinary, chance-related explanation. In such cases, statisticians often are less mystified. When Evelyn Marie Adams won the New Jersey lottery twice, newspapers reported the odds of her feat as 1 in 17 trillion. Bizarre? Actually, 1 in 17 trillion are indeed the odds that a given person who buys a single ticket for each of two New Jersey lotteries will win both times. And given the millions of people who buy U.S. state lottery tickets, stat- isticians Stephen Samuels and George McCabe (1989) reported, it was “practically a sure thing” that someday, somewhere, someone would hit a state jackpot twice. Indeed, said fellow statisticians Persi Diaconis and Frederick Mosteller (1989), “with a large enough sample, any outrageous thing is likely to happen.” An event that happens to but 1 in 1 billion people every day occurs about 7 times a day, over 2500 times a year.

The point to remember: Hindsight bias, overconfidence, and our tendency to perceive patterns in random events often lead us to overestimate our intuition. But scientific inquiry can help us sift reality from illusion.

“The really unusual day would be one where nothing unusual happens.”

Statistician Persi Diaconis (2002)

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Given enough random events, some weird-seeming streaks will occur During the 2010 World Cup, a German octopus—Paul, “the oracle of Oberhausen”— was offered two boxes, each with mussels and with a national flag on one side. Paul selected the right box eight out of eight times in predict- ing the outcome of Germany’s seven matches and Spain’s triumph in the final.

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The Scientific Attitude: Curious, Skeptical, and Humble

1-6: How do the scientific attitude’s three main components relate to critical thinking?

Underlying all science is, first, a hard-headed curiosity, a passion to explore and understand without misleading or being misled. Some questions (Is there life after death?) are beyond science. Answering them in any way requires a leap of faith. With many other ideas (Can some people demonstrate ESP?), the proof is in the pudding. Let the facts speak for themselves.

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14 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

Magician James Randi has used this empirical approach when testing those claiming to see auras around people’s bodies:

RANDI: Do you see an aura around my head?

AURA SEER: Yes, indeed.

RANDI: Can you still see the aura if I put this magazine in front of my face?

AURA SEER: Of course.

RANDI: Then if I were to step behind a wall barely taller than I am, you could determine my location from the aura visible

above my head, right?

Randi told me that no aura seer has agreed to take this simple test.

No matter how sensible-seeming or wild an idea, the smart thinker asks: Does it work? When put to the test, can its predictions be confirmed? Subjected to such

scrutiny, crazy-sounding ideas sometimes find support. More often, science becomes society’s garbage disposal, sending crazy-sounding ideas to the waste heap, atop previous claims of perpetual motion machines, miracle cancer cures, and out-of-body travels into centuries past. To sift reality from fantasy, sense from nonsense, therefore requires a scientific attitude: being skeptical but not cynical, open but not gullible.

“To believe with certainty,” says a Polish proverb, “we must begin by doubting.” As scientists, psychologists approach the world of behavior with a curious skepticism, persis- tently asking two questions: What do you mean? How do you know?

Putting a scientific attitude into practice requires not only curiosity and skepticism but also humility—an awareness of our own vulnerability to error and an openness to surprises and new perspectives. In the last analysis, what matters is not my opinion or yours, but the truths nature reveals in response to our questioning. If people or other animals don’t behave as our ideas predict, then so much the worse for our ideas. This humble attitude was expressed in one of psychology’s early mottos: “The rat is always right.”

Historians of science tell us that these three attitudes—curiosity, skepticism, and humility—helped make modern science possible. Some deeply religious people today may view science, including psychological science, as a threat. Yet, many of the leaders of the scientific revolution, including Copernicus and Newton, were deeply religious people acting on the idea that “in order to love and honor God, it is necessary to fully appreciate the wonders of his handiwork” (Stark, 2003a,b).

Of course, scientists, like anyone else, can have big egos and may cling to their pre- conceptions. Nevertheless, the ideal of curious, skeptical, humble scrutiny of competing ideas unifies psychologists as a community as they check and recheck one another’s findings and conclusions.

The Amazing Randi The magician James Randi exemplifies skepticism. He has tested and debunked a variety of psychic phenomena. AP Photo/Alan Diaz

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“I’m a skeptic not because I do not want to believe but because I want to know. I believe that the truth is out there. But how can we tell the difference between what we would like to be true and what is actually true? The answer is science.”

Michael Shermer, “I Want to Believe,” Scientific American, 2009

“My deeply held belief is that if a god anything like the traditional sort exists, our curiosity and intelligence are provided by such a god. We would be unappreciative of those gifts . . . if we suppressed our passion to explore the universe and ourselves.”

Carl Sagan, Broca’s Brain, 1979

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 15

“The real purpose of the scientific method is to make sure Nature hasn’t misled you into thinking you know something you don’t actually know.”

Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance, 1974

critical thinking thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions.

theory an explanation using an integrated set of principles that organizes observations and predicts behaviors or events.

Critical Thinking The scientific attitude prepares us to think smarter. Smart thinking, called critical thinking, examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions. Whether reading a news report or listening to a conversation, critical think- ers ask questions. Like scientists, they wonder, How do they know that? What is this person’s agenda? Is the conclusion based on anecdote and gut feelings, or on evidence? Does the evidence justify a cause - effect conclusion? What alternative explanations are possible?

Has psychology’s critical inquiry been open to surprising findings? The answer, as ensuing chapters illustrate, is plainly Yes. Believe it or not, massive losses of brain tissue early in life may have minimal long-term effects (see Chapter 2). Within days, new- borns can recognize their mother’s odor and voice (see Chapter 4). After brain damage, a person may be able to learn new skills yet be unaware of such learning (see Chapter 8). Diverse groups—men and women, old and young, rich and middle class, those with disabilities and without—report roughly comparable levels of personal happiness (see Chapter 11).

And has critical inquiry convincingly debunked popular presumptions? The answer, as ensuing chapters also illustrate, is again Yes. The evidence indicates that sleepwalk- ers are not acting out their dreams (see Chapter 3). Our past experiences are not all recorded verbatim in our brains; with brain stimulation or hypnosis, one cannot simply “hit the replay button” and relive long-buried or repressed memories (see Chapter 8). Most people do not suffer from unrealistically low self-esteem, and high self-esteem is not all good (see Chapter 12). Opposites do not generally attract (see Chapter 13). In each of these instances and more, what psychological science has learned is not what is widely believed.

RETRIEVE IT

• How does the scientific attitude contribute to critical thinking?

ANSWER: The scientific attitude combines (1) curiosity about the world around us, (2) skepticism toward various claims and ideas, and (3) humility about one’s own understanding. Evaluating evidence, assessing conclusions, and examining our own assumptions are essential parts of critical thinking.

How Do Psychologists Ask and Answer Questions? Psychologists arm their scientific attitude with the scientific method—a self-correcting process for evaluating ideas with observation and analysis. In its attempt to describe and explain human nature, psychological science welcomes hunches and plausible - sounding theories. And it puts them to the test. If a theory works—if the data support its pre- dictions—so much the better for that theory. If the predictions fail, the theory will be revised or rejected.

The Scientific Method

1-7: How do theories advance psychological science?

In everyday conversation, we often use theory to mean “mere hunch.” In sci- ence, a theory explains with principles that organize observations and predict

behaviors or events. By organizing isolated facts, a theory simplifies. By linking facts with deeper principles, a theory offers a useful summary. As we connect the observed dots, a coherent picture emerges.

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16 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

A good theory about sleep deprivation’s effects on memory, for example, helps us organize countless sleep-related observations into a short list of principles. Imagine that we observe over and over that people with good sleep habits tend to answer questions accurately in class, and they do well at test time. We might therefore theorize that sleep improves memory. So far so good: Our sleep-retention principle neatly summarizes a list of facts about the effects of sleep loss.

Yet no matter how reasonable a theory may sound—and it does seem reasonable to suggest that sleep loss could affect memory—we must put it to the test. A good theory produces testable predictions, called hypotheses. By enabling us to test and to reject or revise our theory, such predictions direct research. They specify what results would support the theory and what results would disconfirm it. To test our theory about the effects of sleep on memory, we might assess people’s retention of course materials after a good night’s sleep, or a shortened night’s sleep (FIGURE 1.2).

Our theories can bias our observations. Having theorized that better memory springs from more sleep, we may see what we expect: We may perceive sleepy people’s com- ments as less insightful. The urge to see what we expect is ever - present, both inside and outside the laboratory, as when people’s views of climate change influence their inter- pretation of local weather events.

As a check on their biases, psychologists report their research with precise opera- tional definitions of procedures and concepts. Hunger, for example, might be defined as “hours without eating,” generosity as “money contributed,” sleep loss as “hours less” than one’s natural sleep. Using these carefully worded statements, others can replicate (repeat) the original observations with different participants, materials, and circum- stances. If they get similar results, confidence in the finding’s reliability grows. The first study of hindsight bias aroused psychologists’ curiosity. Now, after many successful rep- lications with different people and questions, we feel sure of the phenomenon’s power.

In the end, our theory will be useful if it (1) organizes a range of self - reports and observations, and (2) implies predictions that anyone can use to check the theory or to derive practical applications. (Does people’s sleep predict their retention?) Eventually, our research may lead to a revised theory that better organizes and predicts what we know. Or, our research may be replicated and supported by similar findings. (This has been the case for sleep and memory studies, as you will see in Chapter 3.)

As we will see next, we can test our hypotheses and refine our theories using descriptive methods (which describe behaviors, often through case studies, naturalistic

Research and observations Example: Give study material to people before (a) an ample night’s sleep, or (b) a shortened night’s sleep, then test memory.

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lead to

Example: Sleep boosts memory.

Hypotheses Example: When sleep deprived, people remember less from the day before.

confirm, reject, or revise

hypothesis a testable prediction, often implied by a theory.

operational definition a statement of the procedures (operations) used to define research variables. For example, human intelligence may be operationally defined as “what an intelli- gence test measures.”

replication repeating the essence of a research study, usually with different partici- pants in different situations, to see whether the basic finding extends to other participants and circumstances.

For more information about statistical methods that psychological scientists use in their work, see Appendix A, Statistical Reasoning in Everyday Life.

FIGURE 1.2

The scientific method A self - correcting process for asking questions and observing nature’s answers.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 17

observations, or surveys), correlational methods (which associate different factors), and experimental methods (which manipulate factors to discover their effects). To think criti- cally about popular psychology claims, we need to understand these methods and know what conclusions they allow.

RETRIEVE IT

• What does a good theory do?

ANSWER: 1. It organizes observed facts. 2. It implies hypotheses that offer testable predictions and, sometimes, practical applications.

• Why is replication important?

ANSWER: Psychologists watch eagerly for new findings, but they also proceed with caution—by awaiting other investigators’ repeating the research. Can the finding be confirmed (the result replicated)?

Description

1-8: How do psychologists use case studies, naturalistic observations, and surveys to observe and describe behavior, and why is random sampling important?

The starting point of any science is description. In everyday life, we all observe and describe people, often drawing conclusions about why they act as they do. Professional psychologists do much the same, though more objectively and systematically, through

• case studies (in-depth analyses of special individuals). • naturalistic observation (watching and recording individuals’ behavior in their natural

setting).

• surveys and interviews (self-reports in which people answer questions about their behavior or attitudes).

The Case Study Among the oldest research methods, the case study examines one individual in depth in the hope of revealing things true of us all. Some examples: Much of our early knowl- edge about the brain came from case studies of individuals who suffered a particular impairment after damage to a certain brain region. Jean Piaget taught us about children’s thinking after carefully observing and questioning only a few children. Studies of only a few chimpanzees revealed their capacity for understanding and language. Intensive case studies are sometimes very revealing. They show us what can happen, and they often suggest directions for further study.

But individual cases may mislead us if the individual is atypical. Unrepresentative information can lead to mistaken conclusions. Indeed, anytime a researcher mentions a finding (“Smokers die younger: 95 percent of men over 85 are nonsmokers”) someone is sure to offer a contradictory anecdote (“Well, I have an uncle who smoked two packs a day and lived to be 89”). Dramatic stories and personal experiences (even psychological case examples) command our attention and are easily remembered. Journalists understand that, and so begin an article about bank foreclosures with the sad story of one family put out of their house, not with foreclosure statistics. Stories move us. But stories can mislead. Which of the following do you find more memorable? (1) “In one study of 1300 dream reports concerning a kidnapped child, only 5 percent correctly envisioned the child as dead” (Murray & Wheeler, 1937). (2) “I know a man who dreamed his sister was in a car accident, and two days later she died in a head-on collision!” Num- bers can be numbing, but the plural of anecdote is not evidence. As psychologist Gordon Allport (1954, p. 9) said, “Given a thimbleful of [dramatic] facts we rush to make generalizations as large as a tub.”

case study an observation technique in which one person is studied in depth in the hope of revealing universal principles.

Freud and Little Hans Sigmund Freud’s case study of 5-year-old Hans’ extreme fear of horses led Freud to his theory of childhood sexu- ality. He conjectured that Hans felt unconscious desire for his mother, feared castration by his rival father, and then transferred this fear into his phobia about being bitten by a horse. As Chapter 12 will explain, today’s psychological science discounts Freud’s theory of childhood sexuality but acknowledges that much of the human mind operates outside our conscious awareness. Skye Hohmann/Alamy

“‘Well my dear,’ said Miss Marple, ‘human nature is very much the same everywhere, and of course, one has opportunities of observing it at closer quarters in a village.’”

Agatha Christie, The Tuesday Club Murders, 1933

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18 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

A natural observer Chimpanzee researcher Frans de Waal (2005) reported, “I am a born observer. . . . When picking a seat in a restaurant I want to face as many tables as possible. I enjoy following the social dynam- ics—love, tension, boredom, antipathy—around me based on body language, which I consider more informative than the spoken word. Since keeping track of others is something I do auto- matically, becoming a fly on the wall of an ape colony came naturally to me.”

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Naturalistic observations also illuminate human behavior. Here are three findings you might enjoy:

• A funny finding. We humans laugh 30 times more often in social situations than in solitary situations. (Have you noticed how seldom you laugh when alone?) As we laugh, 17 muscles contort our mouth and squeeze our eyes, and we emit a series of 75-millisecond vowel - like sounds, spaced about one - fifth of a second apart (Provine, 2001).

The point to remember: Individual cases can suggest fruitful ideas. What’s true of all of us can be glimpsed in any one of us. But to discern the general truths that cover individual cases, we must answer questions with other research methods.

RETRIEVE IT

• Case studies do not enable us to learn about general principles that apply to all of us. Why not?

ANSWER: Case studies involve only one individual, so we can’t know for sure whether the principles observed would apply to a larger population.

Naturalistic Observation A second descriptive method records behavior in natural environments. These naturalistic observations range from watching chimpanzee societies in the jungle, to unobtrusively videotaping (and later systematically analyzing) parent-child interactions in different cultures, to recording racial differences in students’ self-seating patterns in a school lunchroom.

Like the case study, naturalistic observation does not explain behavior. It describes it. Nevertheless, descriptions can be revealing. We once thought, for example, that only humans use tools. Then naturalistic observation revealed that chimpanzees sometimes insert a stick in a termite mound and withdraw it, eating the stick’s load of termites. Such unobtrusive naturalistic observations paved the way for later studies of animal thinking, language, and emotion, which further expanded our understanding of our fellow animals. “Observations, made in the natural habitat, helped to show that the societies and behavior of animals are far more complex than previously supposed,” chimpanzee observer Jane Goodall noted (1998). Thanks to researchers’ observations, we know that chimpanzees and baboons use deception. Psychologists Andrew Whiten and Richard Byrne (1988) repeatedly saw one young baboon pretending to have been attacked by another as a tactic to get its mother to drive the other baboon away from its food. The more developed a primate species’ brain, the more likely it is that the animals will display deceptive behaviors (Byrne & Corp, 2004).

naturalistic observation observing and recording behavior in naturally occurring situ- ations without trying to manipulate and control the situation.

survey a technique for ascertaining the self - reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 19

An EAR for naturalistic observation Psychologists Matthias Mehl and James Pennebaker have used Electronically Activated Recorders (EARs) to sample naturally occurring slices of daily life.

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• Sounding out students. What, really, are introductory psychology students saying and doing during their everyday lives? To find out, Matthias Mehl and James Pennebaker (2003) equipped 52 such students from the University of Texas with belt-worn Electronically Activated Recorders (EARs). For up to four days, the EAR captured 30 seconds of the student’s waking hours every 12.5 minutes, thus enabling the researchers to eavesdrop on more than 10,000 half - minute life slices by the end of the study. On what percentage of the slices do you suppose they found the students talking with someone? What percentage captured the students at a computer keyboard? The answers: 28 and 9 percent. (What percentage of your waking hours are spent in these activities?)

• Culture, climate, and the pace of life. Naturalistic observation also enabled Robert Levine and Ara Norenzayan (1999) to compare the pace of life in 31 countries. (Their operational definition of pace of life included walking speed, the speed with which postal clerks completed a simple request, and the accuracy of public clocks.) Their conclusion: Life is fastest paced in Japan and Western Europe and slower paced in economically less - developed countries. People in colder climates also tend to live at a faster pace (and are more prone to die from heart disease).

Naturalistic observation offers interesting snapshots of everyday life, but it does so with- out controlling for all the factors that may influence behavior. It’s one thing to observe the pace of life in various places, but another to understand what makes some people walk faster than others.

RETRIEVE IT

• What are the advantages and disadvantages of naturalistic observation, such as Mehl and Pennebaker used in their study?

ANSWER: Mehl and Pennebaker were able to carefully observe and record naturally occurring behaviors outside the artificiality of the lab. However, outside the lab they were not able to control for all the factors that may have influenced the everyday interactions they were recording.

The Survey A survey looks at many cases in less depth. A survey asks people to report their behavior or opinions. Questions about everything from sexual practices to political opinions are put to the public. In recent surveys,

• half of all Americans reported experiencing more happiness and enjoyment than worry and stress on the previous day (Gallup, 2010).

• 1 in 5 people across 22 countries reported believing that alien beings have come to Earth and now walk among us disguised as humans (Ipsos, 2010b).

• 68 percent of all humans—some 4.6 billion people—say that religion is important in their daily lives (Diener et al., 2011).

But asking questions is tricky, and the answers often depend on question wording and respondent selection.

Wording Effects Even subtle changes in the order or wording of questions can have major effects. People are much more approving of “aid to the needy” than of “welfare,” of “affirmative action” than of “preferential treatment,” of “not allowing” televised ciga- rette ads and pornography than of “censoring” them, and of “revenue enhancers” than of “taxes.” In 2009, three in four Americans in one national survey approved of giving people “a choice” of public (government-run) or private health insurance. Yet in another survey, most Americans were not in favor of “creating a public health care plan administered by the federal government that would compete directly with private health insurance com- panies” (Stein, 2009). Because wording is such a delicate matter, critical thinkers will reflect on how the phrasing of a question might affect people’s expressed opinions. Th

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20 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

With very large samples, estimates become quite reliable. E is estimated to represent 12.7 percent of the letters in written English. E, in fact, is 12.3 percent of the 925,141 letters in Melville’s Moby Dick, 12.4 percent of the 586,747 letters in Dickens’ A Tale of Two Cities, and 12.1 percent of the 3,901,021 letters in 12 of Mark Twain’s works (Chance News, 1997).

Random Sampling In everyday thinking, we tend to generalize from cases we observe, especially vivid cases. Given (a) a statistical summary of a professor’s student evaluations and (b) the vivid comments of a biased sample—two irate students—an administrator’s impression of the professor may be influenced as much by the two unhappy students as by the many favorable evaluations in the statistical summary. The temptation to ignore the sampling bias and to generalize from a few vivid but unrepre- sentative cases is nearly irresistible.

So how do you obtain a representative sample—say, of the students at your college or university? It’s not always possible to survey the whole group you want to study and describe. How could you choose a group that would represent the total student popu- lation? Typically, you would seek a random sample, in which every person in the entire group has an equal chance of participating. You might number the names in the general student listing and then use a random number generator to pick your survey participants. (Sending each student a questionnaire wouldn’t work because the consci- entious people who returned it would not be a random sample.) Large representative samples are better than small ones, but a small representative sample of 100 is better than an unrepresentative sample of 500.

Political pollsters sample voters in national election surveys just this way. Using only 1500 randomly sampled people, drawn from all areas of a country, they can provide a remarkably accurate snapshot of the nation’s opinions. Without random sampling, large samples—including call - in phone samples and TV or website polls—often merely give misleading results.

The point to remember: Before accepting survey findings, think critically: Consider the sample. The best basis for generalizing is from a representative sample. You cannot com- pensate for an unrepresentative sample by simply adding more people.

RETRIEVE IT

• What is an unrepresentative sample, and how do researchers avoid it?

ANSWER: An unrepresentative sample is a survey group that does not represent the population being studied. Random sampling helps researchers form a representative sample because each member of the population has an equal chance of being included.

Correlation

1-9: What are positive and negative correlations, and why do they enable prediction but not cause-effect explanation?

Describing behavior is a first step toward predicting it. Naturalistic observa- tions and surveys often show us that one trait or behavior is related to another. In such cases, we say the two correlate. A statistical measure (the correlation coefficient) indicates how closely two things vary together, and thus how well either one predicts the other. Knowing how much aptitude test scores correlate with school success tells us how well the scores predict school success.

A positive correlation (between 0 and +1.00) indicates a direct relationship, meaning that two things increase together or decrease together.

A negative correlation (between 0 and −1.00) indicates an inverse relationship: As one thing increases, the other decreases. The weekly number of hours spent in TV watching and video gaming correlates negatively with grades. Negative correlations could go as low as −1.00, which means that, like people on the opposite ends of a teeter - totter, one set of scores goes down precisely as the other goes up.

Though informative, psychology’s correlations usually leave most of the variation among individuals unpredicted. As we will see, there is a positive correlation between parents’ abusiveness and their children’s later abusiveness when they become parents. But

population all those in a group being stud- ied, from which samples may be drawn. (Note: Except for national studies, this does not refer to a country’s whole population.)

random sample a sample that fairly repre- sents a population because each member has an equal chance of inclusion.

correlation a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

correlation coefficient a statistical index of the relationship between two things (from −1 to +1).

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 21

© Nancy Brown/Getty Images

this does not mean that most abused children become abusive. The correlation simply indicates a statistical relationship: Most abused children do not grow into abusers, but nonabused children are even less likely to become abusive. Correlations point us toward predictions, but usually imperfect ones.

The point to remember: A correlation coefficient helps us see the world more clearly by revealing the extent to which two things relate.

RETRIEVE IT

• Indicate whether each of the following statements describes a positive correlation or a negative correlation.

1. The more children and youth use various media, the less happy they are with their lives (Kaiser, 2010).

2. The more sexual content teens see on TV, the more likely they are to have sex (Collins et al., 2004).

3. The longer children were breast-fed, the greater their later academic achievement (Horwood & Ferguson, 1998).

4. The more income rose among a sample of poor families, the fewer psychiatric symptoms their children experienced (Costello et al., 2003).

ANSWERS: 1. negative, 2. positive, 3. positive, 4. negative

Correlation and Causation Correlations help us predict. The New York Times reports that U.S. counties with high gun ownership rates tend to have high murder rates (Luo, 2011). Gun ownership pre- dicts homicide. What might explain this guns-homicide correlation?

I can almost hear someone thinking, “Well, of course, guns kill people, often in moments of passion.” If so, that could be an example of A (guns) causes B (murder). But I can hear other readers saying, “Not so fast. Maybe people in dangerous places buy more guns for self-protection—maybe B causes A.” Or maybe some third factor C causes both A and B.

Another example: Self-esteem correlates negatively with (and therefore predicts) depression. (The lower people’s self-esteem, the more they are at risk for depression.) So, does low self-esteem cause depression? If, based on the correlational evidence, you assume that it does, you have much company. A nearly irresistible thinking error is assuming that an association, sometimes presented as a correlation coefficient, proves causation. But no matter how strong the relationship, it does not.

RETRIEVE IT

• Length of marriage correlates with hair loss in men. Does this mean that marriage causes men to lose their hair (or that balding men make better husbands)?

As options 2 and 3 in FIGURE 1.3 on the next page show, we’d get the same negative correlation between self-esteem and depression if depression caused people to be down on themselves, or if some third factor—such as heredity or distressing events—caused both low self-esteem and depression.

This point is so important—so basic to thinking smarter with psychology— that it merits one more example. A survey of over 12,000 adolescents found that the more teens feel loved by their parents, the less likely they are to behave in unhealthy ways—having early sex, smoking, abusing alcohol and drugs, exhibiting violence (Resnick et al., 1997). “Adults have a powerful effect on their children’s

ANSWER: In this case, as in many others, a third factor obviously explains the correlation: Golden anniversaries and baldness both accompany aging.

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22 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

behavior right through the high school years,” gushed an Associated Press (AP) story reporting the finding. But this correlation comes with no built- in cause - effect arrow. The AP could as well have reported, “Well - behaved teens feel their parents’ love and approval; out - of - bounds teens more often think their parents are disapproving.”

The point to remember (turn the volume up here): Association does not prove causation. Correlation indicates the possibility of a cause - effect relationship but does not prove such. Remember this principle and you will be wiser as you read and hear news of scientific studies.

Experimentation

1-10: What are the characteristics of experimentation that make it possible to isolate cause and effect?

Happy are they, remarked the Roman poet Virgil, “who have been able to perceive the causes of things.” How might psychologists perceive causes in correlational studies, such as the correlation between breast feeding and intelligence?

Researchers have found that the intelligence scores of children who were breast-fed as infants are somewhat higher than the scores of children who were bottle-fed with cow’s milk (Angelsen et al., 2001; Mortensen et al., 2002; Quinn et al., 2001). In Brit- ain, breast-fed babies have also been more likely than their bottle-fed counterparts to eventually move into a higher social class (Martin et al., 2007). But the “breast is best” intelligence effect shrinks when researchers compare breast-fed and bottle-fed children from the same families (Der et al., 2006).

What do such findings mean? Do smarter mothers (who in modern countries more often breast feed) have smarter children? Or, as some researchers believe, do the nutrients of mother’s milk contribute to brain development? To find answers to such ques- tions—to isolate cause and effect—researchers can experiment. Experiments enable researchers to isolate the effects of one or more factors by (1) manipulating the factors of interest and (2) holding constant (controlling) other factors. To do so, they often create an experimental group, in which people receive the treatment, and a contrasting control group whose members do not receive the treatment. To minimize any preexisting differences between the two groups, researchers randomly assign people to the two conditions. If one-third of the volunteers for an experiment can wiggle their ears, then about one-third of the people in each group will be ear

A New York Times writer reported a massive survey showing that “adolescents whose parents smoked were 50 percent more likely than children of nonsmokers to report having had sex.” He concluded (would you agree?) that the survey indicated a causal effect—that “to reduce the chances that their children will become sexually active at an early age” parents might “quit smoking” (O’Neil, 2002).

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experiment a research method in which an investigator manipulates one or more fac- tors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant factors.

experimental group in an experiment, the group exposed to the treatment, that is, to one version of the independent variable.

control group in an experiment, the group not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

random assignment assigning partici- pants to experimental and control groups by chance, thus minimizing preexisting differences between the different groups.

FIGURE 1.3

Three possible cause -effect

relationships People low in self -esteem are more likely to report depression than are those high in self - esteem. One possible explanation of this negative correlation is that a bad self - image causes depressed feelings. But, as the diagram indicates, other cause- effect relationships are possible.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 23

“If I don’t think it’s going to work, will it still work?”

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double - blind procedure an experimen- tal procedure in which both the research partici- pants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug - evaluation studies.

placebo [pluh - SEE-bo; Latin for “I shall please”] effect experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert sub- stance or condition, which the recipient assumes is an active agent.

wigglers. So, too, with ages, attitudes, and other characteristics, which will be similar in the experimental and control groups. Thus, if the groups differ at the experiment’s end, we can surmise that the treatment had an effect.

To experiment with breast feeding, one research team randomly assigned some 17,000 Belarus newborns and their mothers either to a breast-feeding-promotion group or to a normal pediatric care program (Kramer et al., 2008). At three months of age, 43 percent of the experimental group infants were being exclusively breast-fed, as were 6 percent in the control group. At age 6, when nearly 14,000 of the children were restud- ied, those who had been in the breast-feeding-promotion group had intelligence test scores averaging six points higher than their control group counterparts.

No single experiment is conclusive, of course. But randomly assigning participants to one feeding group or the other effectively eliminated all factors except nutrition. This supported the conclusion that breast is indeed best for developing intelligence: If a behavior (such as test performance) changes when we vary an experimental factor (such as infant nutrition), then we infer that the factor is having an effect.

The point to remember: Unlike correlational studies, which uncover naturally occurring relationships, an experiment manipulates a factor to determine its effect.

Consider, then, how we might assess therapeutic interventions. Our tendency to seek new remedies when we are ill or emotionally down can produce misleading testimonies. If three days into a cold we start taking vitamin C tablets and find our cold symptoms lessening, we may credit the pills rather than the cold naturally subsiding. In the 1700s, bloodletting seemed effective. People sometimes improved after the treatment; when they didn’t, the practitioner inferred the disease was too advanced to be reversed. So, whether or not a remedy is truly effective, enthusiastic users will probably endorse it. To deter- mine its effect, we must control for other factors.

And that is precisely how investigators evaluate new drug treatments and new methods of psychological therapy (Chapter 15). They randomly assign participants either to the group receiving a treatment (such as a medication), or to a group receiving a pseudo- treatment—an inert placebo (perhaps a pill with no drug in it). The participants are often blind (uninformed) about what treatment, if any, they are receiving. If the study is using a double-blind procedure, neither the participants nor those who administer the drug or placebo and collect the data will know which group is receiving the treatment.

In such studies, researchers can check a treatment’s actual effects apart from the par- ticipants’ and the staff ’s belief in its healing powers. Just thinking you are getting a treat- ment can boost your spirits, relax your body, and relieve your symptoms. This placebo effect is well documented in reducing pain, depression, and anxiety (Kirsch, 2010). And the more expensive the placebo, the more “real” it seems to us—a fake pill that costs $2.50 works better than one costing 10 cents (Waber et al., 2008). To know how effec- tive a therapy really is, researchers must control for a possible placebo effect.

RETRIEVE IT

• What measure do researchers use to prevent the placebo effect from confusing their results?

ANSWER: Research designed to prevent the placebo effect randomly assigns participants to an experimental group (which receives the real treatment) or to a control group (which receives a placebo). A comparison of the results will demonstrate whether the real treatment produces better results than belief in that treatment.

Independent and Dependent Variables Here is an even more potent example: The drug Viagra was approved for use after 21 clinical trials. One trial was an experiment in which researchers randomly assigned 329 men with erectile dysfunction to either an experimental group (Viagra takers) or a con- trol group (placebo takers). It was a double - blind procedure—neither the men nor the person giving them the pills knew what they were receiving. The result: At peak doses, 69 percent of Viagra - assisted attempts at intercourse were successful, compared with 22 percent for men receiving the placebo (Goldstein et al., 1998). Viagra worked.

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24 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

Group Independent

variable Dependent

variable

Experimental Promoted

breast feeding Intelligence score, age 6

Control Did not promote breast feeding

Intelligence score, age 6

Random assignment (controlling for other variables such as parental intelligence and environment)

This simple experiment manipulated just one factor: the drug dosage (none versus peak dose). We call this experimental factor the independent variable because we can vary it independently of other factors, such as the men’s age, weight, and personality. These other factors, which could influence the experiment’s results, are called confounding variables. Random assignment controls for possible confounding variables.

Experiments examine the effect of one or more independent variables on some mea- surable behavior, called the dependent variable because it can vary depending on what takes place during the experiment. Both variables are given precise operational definitions, which specify the procedures that manipulate the independent variable (in this study, the precise drug dosage and timing) or measure the dependent variable (the questions that assessed the men’s responses). These definitions answer the “What do you mean?” question with a level of precision that enables others to repeat the study. (See FIGURE 1.4 for the breast milk experiment’s design.)

Let’s pause to check your understanding using a simple psychology experiment: To test the effect of perceived ethnicity on the availability of rental housing, Adrian Carpusor and William Loges (2006) sent identically worded e-mail inquiries to 1115 Los Angeles–area landlords. The researchers varied the ethnic connotation of the sender’s name and tracked the percentage of positive replies (invitations to view the apartment in person). “Patrick McDougall,” “Said Al-Rahman,” and “Tyrell Jackson” received, respec- tively, 89 percent, 66 percent, and 56 percent invitations.

RETRIEVE IT

• In the apartment rental experiment, what was the independent variable? The dependent variable?

ANSWER: The independent variable, which the researchers manipulated, was the ethnicity-related names. The dependent variable, which they measured, was the positive response rate.

Experiments can also help us evaluate social programs. Do early childhood edu- cation programs boost impoverished children’s chances for success? What are the effects of different anti-smoking campaigns? Do school sex - education programs reduce teen pregnancies? To answer such questions, we can experiment: If an inter- vention is welcomed but resources are scarce, we could use a lottery to randomly assign some people (or regions) to experience the new program and others to a control condition. If later the two groups differ, the intervention’s effect will be confirmed (Passell, 1993).

Let’s recap. A variable is anything that can vary (infant nutrition, intelligence, TV exposure—anything within the bounds of what is feasible and ethical). Experiments aim to manipulate an independent variable, measure the dependent variable, and control confound- ing variables. An experiment has at least two different conditions: an experimental condition and a comparison or control condition. Random assignment works to minimize preexisting

independent variable the experimental factor that is manipulated; the variable whose effect is being studied.

confounding variable a factor other than the independent variable that might produce an effect in an experiment.

dependent variable the outcome factor; the variable that may change in response to manipulations of the independent variable.

FIGURE 1.4

Experimentation To discern causation, psychologists may randomly assign some participants to an experimental group, others to a control group. Measuring the dependent variable (intelligence score in later childhood) will determine the effect of the independent variable (whether breast milk was promoted).

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 25

differences between the groups before any treatment effects occur. In this way, an experiment tests the effect of at least one independent variable (what we manipulate) on at least one dependent variable (the outcome we measure). TABLE 1.2 compares the features of psychology’s research methods.

RETRIEVE IT

• Match the term on the left with the description on the right.

1. double-blind procedure a. helps researchers generalize from a small set of survey responses to a larger population

2. random sampling b. helps minimize preexisting differences between experimental and control groups

3. random assignment c. controls for the placebo effect; neither researchers nor participants know who receives the real treatment

ANSWERS: 1. c, 2. a, 3. b

• Why, when testing a new drug to control blood pressure, would we learn more about its effectiveness from giving it to half the participants in a group of 1000 than to all 1000 participants?

ANSWER: To determine the drug’s effectiveness, we must compare its effect on those randomly assigned to receive it (the experimental group) with the other half of the participants (the control group), who receive a placebo. If we gave the drug to all 1000 participants, we would have no way of knowing whether the drug is serving as a placebo or is actually medically effective.

Frequently Asked Questions About Psychology We have reflected on how a scientific approach can restrain biases. We have seen how case studies, naturalistic observations, and surveys help us describe behavior. We have also noted that correlational studies assess the association between two factors, which indi- cates how well one thing predicts another. We have examined the logic that underlies experiments, which use control conditions and random assignment of participants to isolate the effects of an independent variable on a dependent variable.

Yet, even knowing this much, you may still be approaching psychology with a mix- ture of curiosity and apprehension. So before we plunge in, let’s entertain some fre- quently asked questions.

Table 1.2

Comparing Research Methods

Research Method Basic Purpose How Conducted What Is Manipulated Weaknesses

Descriptive To observe and record behavior Do case studies, natu- ralistic observations, or surveys

Nothing No control of variables; single cases may be misleading

Correlational To detect naturally occurring relationships; to assess how well one variable predicts another

Collect data on two or more variables; no manipulation

Nothing Does not specify cause and effect

Experimental To explore cause and effect Manipulate one or more factors; use random assignment

The indepen- dent variable(s)

Sometimes not feasible; results may not generalize to other contexts; not ethical to manipulate certain variables

ComCom

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26 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

1-11: Can laboratory experiments illuminate everyday life?

When you see or hear about psychological research, do you ever wonder whether people’s behavior in the lab will predict their behavior in real life?

For example, does detecting the blink of a faint red light in a dark room reveal anything useful about flying a plane at night? After viewing a violent, sexually explicit film, does an aroused man’s increased willingness to push buttons that he thinks will electrically shock a woman really say anything about whether violent pornography makes a man more likely to abuse a woman?

Before you answer, consider: The experimenter intends the laboratory environment to be a simplified reality—one that simulates and controls important features of everyday life. Just as a wind tunnel lets airplane designers re - create airflow forces under controlled conditions, a laboratory experiment lets psychologists re - create psychological forces under controlled conditions.

An experiment’s purpose is not to re - create the exact behaviors of everyday life but to test theoretical principles (Mook, 1983). In aggression studies, deciding whether to push a button that delivers a shock may not be the same as slapping someone in the face, but the principle is the same. It is the resulting principles—not the specific findings—that help explain everyday behaviors.

When psychologists apply laboratory research on aggression to actual violence, they are applying theoretical principles of aggressive behavior, principles refined through many experiments. Similarly, it is the principles of the visual system, developed from experiments in artificial settings (such as looking at red lights in the dark), that research- ers apply to more complex behaviors such as night flying. And many investigations have demonstrated that principles derived in the laboratory do typically generalize to the everyday world (Anderson et al., 1999).

The point to remember: Psychological science focuses less on particular behaviors than on seeking general principles that help explain many behaviors.

1-12: Does behavior depend on one’s culture and gender?

What can we learn about people in general from psychological studies done in one time and place—often with people from what Joseph Henrich, Ste-

ven Heine, and Ara Norenzayan (2010) call the WEIRD cultures (Western, Educated, Industrialized, Rich, and Democratic cultures that contribute most study participants but are only 12 percent of humanity)? As we will see time and again, culture—shared ideas and behaviors that one generation passes on to the next—matters. Our culture shapes our standards of promptness and frankness, our attitudes toward premarital sex and varying body shapes, our tendency to be casual or formal, our willingness to make eye contact, our conversational distance, and much, much more. Being aware of such dif- ferences, we can restrain our assumptions that others will think and act as we do. Given the growing mixing and clashing of cultures, our need for such awareness is urgent.

It is also true, however, that our shared biological heritage unites us as a universal human family. The same underlying processes guide people everywhere:

• People diagnosed with dyslexia, a reading disorder, exhibit the same brain malfunc- tion whether they are Italian, French, or British (Paulesu et al., 2001).

• Variation in languages may impede communication across cultures. Yet all languages share deep principles of grammar, and people from opposite hemispheres can com- municate with a smile or a frown.

• People in different cultures vary in feelings of loneliness. But across cultures, lone- liness is magnified by shyness, low self-esteem, and being unmarried (Jones et al., 1985; Rokach et al., 2002).

We are each in certain respects like all others, like some others, and like no other. Studying people of all races and cultures helps us discern our similarities and our differ- ences, our human kinship and our diversity.

India is not Indiana Because culture shapes people’s understanding of social behav- ior, actions that seem ordinary to us may seem quite odd to visitors from far away. Yet underly- ing these differences are powerful similarities. Supporters of newly elected leaders everywhere typically greet them with pleased deference, though not necessarily with bows and folded hands, as supporters of influential and popular Indian politician Sonia Gandhi did here.

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culture the enduring behaviors, ideas, atti- tudes, values, and traditions shared by a group of people and transmitted from one generation to the next.

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 27

You will see throughout this book that gender matters, too. Researchers report gender differences in what we dream, in how we express and detect emotions, and in our risk for alcohol dependence, depression, and eating disorders. Gender differences fascinate us, and studying them is potentially beneficial. For example, many researchers believe that women carry on conversations more readily to build relationships, while men talk more to give information and advice (Tannen, 2001). Knowing this difference can help us prevent conflicts and misunderstandings in everyday relationships.

But again, psychologically as well as biologically, women and men are overwhelm- ingly similar. Whether female or male, we learn to walk at about the same age. We expe- rience the same sensations of light and sound. We feel the same pangs of hunger, desire, and fear. We exhibit similar overall intelligence and well - being.

The point to remember: Even when specific attitudes and behaviors vary by gender or across cultures, as they often do, the underlying processes are much the same.

1-13: Why do psychologists study animals, and what ethical guidelines safeguard human and animal research participants?

Many psychologists study animals because they find them fascinating. They want to understand how different species learn, think, and behave. Psychologists also study animals to learn about people. We humans are not like animals; we are animals, sharing a common biology. Animal experiments have therefore led to treatments for human diseases—insulin for diabetes, vaccines to prevent polio and rabies, transplants to replace defective organs.

Humans are more complex, but the same processes by which we learn are present in rats, monkeys, and even sea slugs. The simplicity of the sea slug’s nervous system is precisely what makes it so revealing of the neural mechanisms of learning.

Sharing such similarities, should we respect rather than experiment on our animal relatives? The animal protection movement protests the use of animals in psychological, biological, and medical research.

Out of this heated debate, two issues emerge. The basic one is whether it is right to place the well-being of humans above that of animals. In experiments on stress and cancer, is it right that mice get tumors in the hope that people might not? Should some monkeys be exposed to an HIV-like virus in the search for an AIDS vaccine? Is our use and consumption of other animals as natural as the behavior of carnivorous hawks, cats, and whales? The answers to such questions vary by culture. In Gallup surveys in Canada and the United States, about 60 percent of adults have deemed medical testing on ani- mals “morally acceptable.” In Britain, only 37 percent have (Mason, 2003).

If we give human life first priority, what safeguards should protect the well-being of animals in research? In one survey of animal researchers, 98 percent supported govern- ment regulations protecting primates, dogs, and cats, and 74 percent supported regulations providing for the humane care of rats and mice (Plous & Herzog, 2000). Many profes- sional associations and funding agencies already have such guidelines. British Psychologi- cal Society guidelines call for housing animals under reasonably natural living conditions, with companions for social animals (Lea, 2000). American Psychologi- cal Association (APA) guidelines state that researchers must ensure the “comfort, health, and humane treatment” of animals and minimize “infection, illness, and pain” (APA, 2002). The European Parliament now mandates standards for animal care and housing (Vogel, 2010).

Animals have themselves benefited from animal research. One Ohio team of research psychologists measured stress hormone levels in samples of millions of dogs brought each year to animal shelters. They devised han- dling and stroking methods to reduce stress and ease the dogs’ transition to adoptive homes (Tuber et al., 1999). Other studies have helped improve care and management in animals’ natural habitats. By revealing our behav- ioral kinship with animals and the remarkable intelligence of chimpanzees, gorillas, and other animals, experiments have also led to increased empathy and protection for them. At its best, a psychology concerned for humans and sensitive to animals serves the welfare of both.

“All people are the same; only their habits differ.”

Confucius, 551–479 B.C.E

“Rats are very similar to humans except that they are not stupid enough to purchase lottery tickets.”

Dave Barry, July 2, 2002

“Please do not forget those of us who suffer from incurable diseases or disabilities who hope for a cure through research that requires the use of animals.”

Psychologist Dennis Feeney (1987)

Animal research benefiting animals Thanks partly to research on the benefits of novelty, control, and stimulation, these gorillas have enjoyed an improved quality of life in New York’s Bronx Zoo.

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“The greatness of a nation can be judged by the way its animals are treated.”

Mahatma Gandhi, 1869–1948

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28 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

What about human participants? Does the image of white-coated scientists deliver- ing electric shocks trouble you? If so, you’ll be relieved to know that most psychological studies are free of such stress. With people, blinking lights, flashing words, and pleasant social interactions are more common. Moreover, psychology’s experiments are mild compared with the stress and humiliation often inflicted by reality TV shows. In one episode of The Bachelor, a man dumped his new fiancée—on camera, at the producers’ request—for the woman who earlier had finished second (Collins, 2009).

Occasionally, though, researchers do temporarily stress or deceive people, but only when they believe it is essential to a justifiable end, such as understanding and control- ling violent behavior or studying mood swings. Some experiments won’t work if par- ticipants know everything beforehand. (Wanting to be helpful, the participants might try to confirm the researcher’s predictions.)

The APA ethics code urges researchers to (1) obtain human participants’ informed consent before the experiment, (2) protect them from harm and discomfort, (3) keep information about individual participants confidential, and (4) fully debrief people (explain the research afterward). Moreover, university ethics committees screen research proposals and safeguard participants’ well-being.

1-14: Is psychology free of value judgments?

Psychology is definitely not value free. Values affect what we study, how we study it, and how we interpret results. Researchers’ values influence their

choice of topics. Should we study worker productivity or worker morale? Sex discrimi- nation or gender differences? Conformity or independence? Values can also color “the facts.” As we noted earlier, our preconceptions can bias our observations and interpreta-

tions; sometimes we see what we want or expect to see (FIGURE 1.5). Even the words we use to describe something can reflect our values. Are the

sex acts we do not practice “perversions” or “sexual variations”? In psychology and in everyday speech, labels describe and labels evaluate: One person’s rigidity is another’s consistency. One person’s faith is another’s fanaticism. One country’s

enhanced interrogation techniques, such as cold-water immersion, become torture when practiced by its enemies. Our labeling someone as firm or stubborn, careful or picky, discreet or secretive reveals our own attitudes.

Popular applications of psychology also contain hidden values. If you defer to “pro- fessional” guidance about how to live—how to raise children, how to achieve self-

fulfillment, what to do with sexual feelings, how to get ahead at work—you are accepting value-laden advice. A science of behavior and mental processes can help us reach our goals. But it cannot decide what those goals should be.

Knowledge transforms us. Learning about the solar system and the germ theory of disease alters the way people think and act. Learning about psychology’s findings also changes people: They less often judge psychological disorders as moral failings, treatable by punishment and ostracism. They less often regard and treat women as men’s mental inferiors. They less often view and rear children as ignorant, willful beasts in need of taming. “In each case,” noted Morton Hunt (1990, p. 206), “knowledge has modified attitudes, and, through them, behavior.” Once aware of psychology’s well - researched ideas—about how body and mind connect, how a child’s mind grows, how we construct

our perceptions, how we remember (and misremember) our experiences, how people across the world differ (and are alike)—your mind may never again be quite the same.

But bear in mind psychology’s limits. Don’t expect it to answer the ultimate ques- tions, such as those posed by Russian novelist Leo Tolstoy (1904): “Why should I live? Why should I do anything? Is there in life any purpose which the inevitable death that awaits me does not undo and destroy?”

Although many of life’s significant questions are beyond psychology, some very important ones are illuminated by even a first psychology course. Through painstaking research, psychologists have gained insights into brain and mind, dreams and memories, depression and joy. Even the unanswered questions can renew our sense of mystery

Mike Kemp/Getty Images

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FIGURE 1.5

What do you see? Our expectations influence what we perceive. Did you see a duck or a rabbit? Show some friends this image with the rabbit photo above covered up and see if they are more likely to perceive a duck lying on its back instead. (From Shepard, 1990.)

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 29

informed consent giving potential par- ticipants enough information about a study to enable them to decide whether they wish to participate.

debriefing the postexperimental explana- tion of a study, including its purpose and any deceptions, to its participants.

testing effect enhanced memory after retrieving, rather than simply rereading, information. Also sometimes referred to as a retrieval practice effect or test-enhanced learning.

SQ3R a study method incorporating five steps: Survey, Question, Read, Retrieve, Review.

about “things too wonderful” for us yet to understand. Moreover, your study of psy- chology can help teach you how to ask and answer important questions—how to think critically as you evaluate competing ideas and claims.

If some people see psychology as merely common sense, others have a different con- cern—that it is becoming dangerously powerful. Is it an accident that astronomy is the oldest science and psychology the youngest? To some, exploring the external universe seems far safer than exploring our own inner universe. Might psychology, they ask, be used to manipulate people?

Knowledge, like all power, can be used for good or evil. Nuclear power has been used to light up cities—and to demolish them. Persuasive power has been used to edu- cate people—and to deceive them. Although psychology does indeed have the power to deceive, its purpose is to enlighten. Every day, psychologists are exploring ways to enhance learning, creativity, and compassion. Psychology speaks to many of our world’s great problems—war, overpopulation, prejudice, family crises, crime—all of which involve attitudes and behaviors. Psychology also speaks to our deepest longings—for nourishment, for love, for happiness. Psychology cannot address all of life’s great ques- tions, but it speaks to some mighty important ones.

RETRIEVE IT

• How are human research participants protected?

ANSWER: Ethical principles developed by international psychological organizations urge researchers using human participants to obtain informed consent, to protect them from harm and discomfort, to treat their personal information confidentially, and to fully debrief all participants.

Improve Your Retention– and Your Grades

1-15: How can psychological principles help you learn and remember?

Do you, like most students, assume that the way to cement your new learn- ing is to reread? What helps even more—and what this book therefore encourages—is repeated self-testing and rehearsal of previously studied material. Memory researchers Henry Roediger and Jeffrey Karpicke (2006) call this phenomenon the testing effect. (It is also sometimes called the retrieval practice effect or test-enhanced learning.) They note that “testing is a powerful means of improving learning, not just assessing it.” In one of their studies, students recalled the meaning of 40 previously learned Swahili words much better if tested repeatedly than if they spent the same time restudying the words (Karpicke & Roediger, 2008).

As you will see in Chapter 8, to master information you must actively process it. Your mind is not like your stomach, something to be filled passively; it is more like a muscle that grows stronger with exercise. Countless experiments reveal that people learn and remember best when they put material in their own words, rehearse it, and then retrieve and review it again.

The SQ3R study method incorporates these principles (McDaniel et al., 2009; Robin- son, 1970). SQ3R is an acronym for its five steps: Survey, Question, Read, Retrieve4, Review.

To study a chapter, first survey, taking a bird’s-eye view. Scan the headings, and notice how the chapter is organized.

Before you read each main section, try to answer its numbered Learning Objec- tive Question (for this section: “How can psychological principles help you learn and

Psychology speaks In making its historic 1954 school desegregation decision, the U.S. Supreme Court cited the expert testimony and research of psychologists Kenneth Clark and Mamie Phipps Clark (1947). The Clarks had reported that, when given a choice between Black and White dolls, most African-American children chose the White doll, which seemingly indicated internalized anti-Black prejudice.

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30 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

remember?”). Roediger and Bridgid Finn (2009) have found that “trying and failing to retrieve the answer is actually helpful to learning.” Those who test their understanding before reading, and discover what they don’t yet know, will learn and remember better.

Then read, actively searching for the answer to the question. At each sitting, read only as much of the chapter (usually a single main section) as you can absorb without tiring. Read actively and critically. Ask questions. Take notes. Make the ideas your own: How does what you’ve read relate to your own life? Does it support or challenge your assumptions? How convincing is the evidence?

Having read a section, retrieve its main ideas. Test yourself. This will help you figure out what you know. Moreover, the testing itself will help you learn and retain the informa- tion more effectively. Even better, test yourself repeatedly. To facilitate this, I offer peri- odic Retrieve It opportunities throughout each chapter (see, for example, the questions on pages 29 and 31). After trying to answer these questions yourself, you can check the inverted answers, and reread as needed.

Finally, review: Read over any notes you have taken, again with an eye on the chap- ter’s organization, and quickly review the whole chapter. Write or say what a concept is before rereading to check your understanding.

Survey, question, read, retrieve, review. I have organized this book’s chapters to facili- tate your use of the SQ3R study system. Each chapter begins with a chapter outline that aids your survey. Headings and Learning Objective Questions suggest issues and concepts you should consider as you read. The material is organized into sections of readable length. The Retrieve It questions will challenge you to retrieve what you have learned, and thus better remember it. The end-of-chapter Review provides more opportunities for active processing and self-testing, focusing on the chapter’s key terms and Learning Objective Questions. Complete Chapter Reviews can be found in Appendix D, at the end of this book.

Four additional study tips may further boost your learning: Distribute your study time. One of psychology’s oldest findings is that spaced prac-

tice promotes better retention than does massed practice. You’ll remember material better if you space your practice time over several study periods—perhaps one hour a day, six days a week—rather than cram it into one long study blitz. For example, rather than try- ing to read an entire chapter in a single sitting, read just one main section and then turn to something else. Interleaving your study of psychology with your study of other subjects will boost your long-term retention and will protect against overconfidence (Kornell & Bjork, 2008; Taylor & Rohrer, 2010).

Spacing your study sessions requires a disciplined approach to managing your time. (Richard O. Straub explains time management in a helpful preface at the beginning of this text.)

Learn to think critically. Whether you are reading or in class, note people’s assumptions and values. What perspective or bias underlies an argument? Evaluate evi- dence. Is it anecdotal? Or is it based on informative experiments? Assess conclusions. Are there alternative explanations?

Process class information actively. Listen for a lecture’s main ideas and sub-ideas. Write them down. Ask questions during and after class. In class, as in your private study, process the information actively and you will understand and retain it better. As psy- chologist William James urged a century ago, “No reception without reaction, no impression without . . . expression.” Make the information your own. Take notes in your own words. Relate what you read to what you already know. Tell someone else about it. (As any teacher will confirm, to teach is to remember.)

Overlearn. Psychology tells us that overlearning improves retention. We are prone to overestimating how much we know. You may understand a chapter as you read it, but that feeling of familiarity can be deceptively comforting. Using the Retrieve It oppor- tunities, devote extra study time to testing your knowledge.

Memory experts Elizabeth Bjork and Robert Bjork (2011, p. 63) offer the bottom line for how to improve your retention and your grades:

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 31

Spend less time on the input side and more time on the output side, such as summarizing what you have read from memory or getting together with friends and asking each other questions. Any activities that involve testing yourself—that is, activities that require you to retrieve or generate information, rather than just representing information to yourself— will make your learning both more durable and flexible.

RETRIEVE IT

• The

describes the enhanced memory that results from repeated retrieval (as in self-testing) rather than from simple rereading of new information.

ANSWER: testing effect

• What does the acronym SQ3R stand for?

ANSWER: Survey, Question, Read, Retrieve, and Review

CHAPTER REVIEW

Thinking Critically With Psychological Science

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the chapter). Then turn to Appendix D, Complete Chapter Reviews, to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

What is Psychology? 1-1: What are some important milestones in

psychology’s development?

Contemporary Psychology 1-2: What is psychology’s historic big issue?

1-3: What are psychology’s levels of analysis and related perspectives?

1-4: What are psychology’s main subfields?

The Need for Psychological Science 1-5: How do hindsight bias, overconfidence, and the

tendency to perceive order in random events illustrate why science-based answers are more valid than those based on intuition and common sense?

1-6: How do the scientific attitude’s three main components relate to critical thinking?

How Do Psychologists Ask and Answer Questions? 1-7: How do theories advance psychological science?

1-8: How do psychologists use case studies, naturalistic observations, and surveys to observe and describe behavior, and why is random sampling important?

1-9: What are positive and negative correlations, and why do they enable prediction but not cause-effect explanation?

1-10: What are the characteristics of experimentation that make it possible to isolate cause and effect?

Frequently Asked Questions About Psychology 1-11: Can laboratory experiments illuminate everyday life?

1-12: Does behavior depend on one’s culture and gender?

1-13: Why do psychologists study animals, and what ethical guidelines safeguard human and animal research participants?

1-14: Is psychology free of value judgments?

Improve Your Retention—and Your Grades 1-15: How can psychological principles help you learn

and remember?

LEARNING OBJECTIVES

s Ask and A

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32 CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

Test yourself on these terms by trying to write down the definition in your own words before flipping back to the referenced page to check your answer.

structuralism, p. 3

functionalism, p. 3

behaviorism, p. 4

humanistic psychology, p. 4

cognitive neuroscience, p. 4

psychology, p. 4

nature–nurture issue, p. 5

natural selection, p. 6

levels of analysis, p. 6

biopsychosocial approach, p. 6

basic research, p. 9

applied research, p. 9

counseling psychology, p. 9

clinical psychology, p. 9

psychiatry, p. 9

positive psychology, p. 9

hindsight bias, p. 11

critical thinking, p. 15

theory, p. 15

hypothesis, p. 16

operational definition, p. 16

replication, p. 16

case study, p. 17

naturalistic observation, p. 18

survey, p. 19

population, p. 20

random sample, p. 20

correlation, p. 20

correlation coefficient, p. 20

experiment, p. 22

experimental group, p. 22

control group, p. 22

random assignment, p. 22

double - blind procedure, p. 23

placebo effect, p. 23

independent variable, p. 24

confounding variable, p. 24

dependent variable, p. 24

culture, p. 26

informed consent, p. 28

debriefing, p. 28

testing effect, p. 29

SQ3R, p. 29

TERMS AND CONCEPTS TO REMEMBER

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

1. In 1879, in psychology’s first experiment, and his students measured the time lag between hearing a ball hit a platform and pressing a key.

2. William James would be considered a(n) . Wilhelm Wundt and Edward Titchener would be considered .

a. functionalist; structuralists b. structuralist; functionalists c. evolutionary theorist; structuralists d. functionalist; evolutionary theorists

3. In the early twentieth century, redefined psychology as “the science of observable behavior.”

a. John B. Watson b. Abraham Maslow c. William James d. Sigmund Freud

4. Nature is to nurture as a. personality is to intelligence. b. biology is to experience. c. intelligence is to biology. d. psychological traits are to behaviors.

5. “Nurture works on what nature endows.” Describe what this means, using your own words.

6. A psychologist treating emotionally troubled adolescents at a local mental health agency is most likely to be a(n)

a. research psychologist. b. psychiatrist. c. industrial-organizational psychologist. d. clinical psychologist.

7. A mental health professional with a medical degree who can prescribe medication is a .

8. A psychologist conducting basic research to expand psychol- ogy’s knowledge base would be most likely to

a. design a computer screen with limited glare and assess the effect on computer operators’ eyes after a day’s work.

b. treat older people who are overcome by depression. c. observe 3- and 6-year-olds solving puzzles and analyze

differences in their abilities. d. interview children with behavioral problems and suggest

treatments.

9. refers to our tendency to perceive events as obvious or inevitable after the fact.

10. As scientists, psychologists a. approach research with a negative cynicism. b. assume that an article published in a reputable journal

must be true. c. believe that every important human question can be

studied scientifically. d. are willing to ask questions and to reject claims that can-

not be verified by research.

EXPERIENCE THE TESTING EFFECT

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CHAPTER 1 THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE 33

11. How can you use your knowledge of the scientific attitude to help you evaluate claims in the media, even if you’re not a scientific expert on the issue?

12. The predictions implied by a theory are called .

13. Which of the following is NOT one of the techniques psy- chologists use to observe and describe behavior?

a. A case study b. Naturalistic observation

14. You wish to take an accurate poll in a certain country by questioning people who truly represent the country’s adult population. Therefore, you need to ensure that you question a sample of the population.

15. A study finds that the more childbirth training classes women attend, the less pain medication they require during childbirth. This finding can be stated as a (positive/negative) correlation.

16. Knowing that two events are correlated provides a. a basis for prediction. b. an explanation of why the events are related. c. proof that as one increases, the other also increases. d. an indication that an underlying third factor is at work.

17. Here are some recently reported correlations, with interpre- tations drawn by journalists. Knowing just these correlations, can you come up with other possible explanations for each of these? a. Alcohol use is associated with violence. (One interpreta-

tion: Drinking triggers or unleashes aggressive behavior.) b. Educated people live longer, on average, than less-edu-

cated people. (One interpretation: Education lengthens life and enhances health.)

c. Teens engaged in team sports are less likely to use drugs, smoke, have sex, carry weapons, and eat junk food than are teens who do not engage in team sports. (One inter- pretation: Team sports encourage healthy living.)

d. Adolescents who frequently see smoking in movies are more likely to smoke. (One interpretation: Movie stars’ behavior influences impressionable teens.)

18. To explain behaviors and clarify cause and effect, psycholo- gists use .

19. To test the effect of a new drug on depression, we randomly assign people to control and experimental groups. Those in the control group take a pill that contains no medication. This is a .

20. In a double-blind procedure, a. only the participants know whether they are in the con-

trol group or the experimental group. b. experimental and control group members will be care-

fully matched for age, sex, income, and education level.

c. neither the participants nor the researchers know who is in the experimental group or control group.

d. someone separate from the researcher will ask people to volunteer for the experimental group or the control group.

21. A researcher wants to determine whether noise level affects workers’ blood pressure. In one group, she varies the level of noise in the environment and records participants’ blood pressure. In this experiment, the level of noise is the .

22. The laboratory environment is designed to a. exactly re-create the events of everyday life. b. re-create psychological forces under controlled conditions. c. create opportunities for naturalistic observation. d. minimize the use of animals and humans in psychological

research.

23. Which of the following is true regarding gender differences and similarities?

a. Differences between the genders outweigh any similarities. b. Despite some gender differences, the underlying processes

of human behavior are the same. c. Both similarities and differences between the genders

depend more on biology than on environment. d. Gender differences are so numerous that it is difficult to

make meaningful comparisons.

24. In defending their experimental research with animals, psy- chologists have noted that

a. animals’ physiology and behavior can tell us much about our own.

b. animal experimentation sometimes helps animals as well as humans.

c. advancing the well-being of humans justifies animal experimentation.

d. All of these statements are correct.

Find answers to these questions in Appendix E, in the back of the book.

Multiple-format self-tests and more may be found at www.worthpublishers.com/myers.

Experience more of the

TESTING EFFECT

c. Correlational research d. A phone survey

TTT

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BIOLOGY AND BEHAVIOR

NEURAL COMMUNICATION Neurons

The Neural Impulse

How Neurons Communicate

How Neurotransmitters Influence Us

THE NERVOUS SYSTEM The Peripheral Nervous System

The Central Nervous System

THE ENDOCRINE SYSTEM

THE BRAIN Older Brain Structures

CLOSE-UP: The Tools of Discovery—Having Our Head Examined

The Cerebral Cortex

Our Divided Brain

Right-Left Differences in the Intact Brain

BEHAVIOR GENETICS: PREDICTING INDIVIDUAL DIFFERENCES Genes: Our Codes for Life

Twin and Adoption Studies

Gene-Environment Interaction

EVOLUTIONARY PSYCHOLOGY: UNDERSTANDING HUMAN NATURE Natural Selection and Adaptation

Evolutionary Success Helps Explain Similarities

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35

In 2000, a Virginia teacher began collecting sex magazines, visiting child pornog- raphy websites, and then making subtle advances on his young stepdaughter. When his wife called the police, he was arrested and later convicted of child molestation. Though put into a sexual addiction rehabilitation program, he still felt overwhelmed by his sexual urges. The day before being sentenced to prison, he went to his local emergency room complaining of a headache and thoughts of suicide. He was also distraught over his uncontrollable impulses, which led him to proposition nurses.

A brain scan located the problem—in his mind’s biology. Behind his right temple there was an egg-sized brain tumor. After surgeons removed the tumor, his lewd impulses faded and he returned home to his wife and stepdaughter. Alas, a year later the tumor partially grew back, and with it the sexual urges. A second tumor removal again lessened the urges (Burns & Swerdlow, 2003).

This case illustrates what you likely believe: that you reside in your head. If surgeons transplanted all your organs below your neck, and even your skin and limbs, you would (Yes?) still be you. An acquaintance of mine received a new heart from a woman who, in a rare operation, had required a matched heart-lung transplant. When the two chanced to meet in their hospital

ward, she introduced herself: “I think you have my heart.” But only her heart. Her self, she assumed, still resided inside her skull. We rightly presume that our brain enables our mind.

Indeed, no principle is more central to today’s psychology than this: Everything psycho- logical is simultaneously biological.

The Biology of Behavior

CHAPTERR2

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36 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Biology and Behavior 2-1: Why are psychologists concerned with human biology?

Your every idea, every mood, every urge is a biological happening. You love, laugh, and cry with your body. Without your body—your genes, your brain,

your appearance—you would, indeed, be nobody. Although we find it convenient to talk separately of biological and psychological influences on behavior, we need to remember: To think, feel, or act without a body would be like running without legs.

Biological psychologists study the links between our biology and behavior. In this chapter we start small and build from the bottom up—from nerve cells to the brain. We then consider how our genetic histories predispose our shared human nature, and, in combination with our environments, our individual differences.

Neural Communication For scientists, it is a happy fact of nature that the information systems of humans and other animals operate similarly—so similarly that you could not distinguish between small samples of brain tissue from a human and a monkey. This similarity allows researchers to study relatively simple animals to discover how our neural systems oper- ate. Cars differ, but all have engines, accelerators, steering wheels, and brakes. A Martian could study any one of them and grasp the operating principles. Likewise, animals differ, yet their nervous systems operate similarly. Though the human brain is more complex than a rat’s, both follow the same principles.

Neurons

2-2: What are neurons, and how do they transmit information?

Our body’s neural information system is complexity built from simplic- ity. Its building blocks are neurons, or nerve cells. To fathom our thoughts

and actions, memories and moods, we must first understand how neurons work and communicate.

Neurons differ, but all are variations on the same theme (FIGURE 2.1). Each consists of a cell body and its branching fibers. The bushy dendrite fibers receive information and conduct it toward the cell body. From there, the cell’s lengthy axon fiber passes the mes- sage through its terminal branches to other neurons or to muscles or glands. Dendrites listen. Axons speak.

Dendrites (receive messages from other cells)

Cell body (the cell’s life- support center)

Axon (passes messages away

from the cell body to other neurons,

muscles, or glands)

Myelin sheath (covers the axon of some neurons and helps speed neural impulses)

Neural impulse (action potential) (electrical signal traveling down the axon)

Terminal branches of axon (form junctions with other cells)

FIGURE 2.1

A motor neuron

biological psychology the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. (Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psycholo- gists, or biopsychologists.)

neuron a nerve cell; the basic building block of the nervous system.

dendrites a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body.

axon the neuron extension that passes mes- sages through its branches to other neurons or to muscles or glands.

myelin [MY-uh-lin] sheath a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next.

glial cells (glia) cells in the nervous system that support, nourish, and protect neu- rons; they may also play a role in learning and thinking.

action potential a neural impulse; a brief electrical charge that travels down an axon.

threshold the level of stimulation required to trigger a neural impulse.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 37

Unlike the short dendrites, axons may be very long, projecting several feet through the body. A human neuron carrying orders to a leg muscle, for example, has a cell body and axon roughly on the scale of a basketball attached to a rope 4 miles long. Much as home electrical wire is insulated, some axons are encased in a myelin sheath, a layer of fatty tissue that insulates them and speeds their impulses. As myelin is laid down up to about age 25, neural efficiency, judgment, and self-control grows (Fields, 2008). If the myelin sheath degenerates, multiple sclerosis results: Com- munication to muscles slows, with eventual loss of muscle control.

Supporting our billions of nerve cells are nine times as many spidery glial cells (“glue cells”). Neurons are like queen bees; on their own they cannot feed or sheathe themselves. Glial cells are worker bees. They provide nutrients and insulating myelin, guide neural connections, and clean up after neurons send messages to one another. Glia may also play a role in learning and thinking. By “chatting” with neurons they may participate in information trans- mission and memory (Fields, 2009; Miller, 2005).

In more complex animal brains, the proportion of glia to neurons increases. A postmor- tem analysis of Einstein’s brain did not find more or larger-than-usual neurons, but it did reveal a much greater concentration of glial cells than found in an average Albert’s head (Fields, 2004).

The Neural Impulse Neurons transmit messages when stimulated by signals from our senses or when triggered by chemical signals from neighboring neurons. In response, a neuron fires an impulse, called the action potential—a brief electrical charge that travels down its axon.

Depending on the type of fiber, a neural impulse travels at speeds ranging from a sluggish 2 miles per hour to a breakneck 180 miles per hour. But even this top speed is 3 million times slower than that of electricity through a wire. We measure brain activity in milliseconds (thousandths of a second) and computer activity in nanoseconds (billionths of a second). Thus, unlike the nearly instantaneous reactions of a computer, your reaction to a sudden event, such as a child darting in front of your car, may take a quarter-second or more. Your brain is vastly more complex than a computer but slower at executing simple responses. And if you were an elephant—whose round-trip message travel time from a yank on the tail to the brain and back to the tail is 100 times longer than that of a tiny shrew—your reflexes would be slower yet (More et al., 2010).

Like batteries, neurons generate electricity from chemical events. In the neuron’s chemistry-to-electricity process, ions (electrically charged atoms) are exchanged. The fluid outside an axon’s membrane has mostly positively charged ions; a resting axon’s fluid interior has mostly negatively charged ions. When a neuron fires, the first section of the axon opens its gates, rather like sewer covers flipping open, and positively charged sodium ions flood in through the cell membrane (FIGURE 2.2 on the next page). This depolarizes that axon section, causing the next axon channel to open, and then the next, like a line of falling dominos, each tripping the next. During a resting pause, the neuron pumps the positively charged sodium ions back outside. Then it can fire again. The mind boggles when imagining this electrochemical process repeating up to 100 or even 1000 times a second. But this is just the first of many astonishments.

Each neuron is itself a miniature decision-making device performing complex calcula- tions as it receives signals from hundreds, even thousands, of other neurons. Most signals are excitatory, somewhat like pushing a neuron’s accelerator. Some are inhibitory, more like pushing its brake. If excitatory signals minus inhibitory signals exceed a minimum inten- sity, or threshold, the combined signals trigger an action potential. (Think of it this way: If the excitatory party animals outvote the inhibitory party poopers, the party’s on.) The action potential then travels down the axon, which branches into junctions with hundreds or thousands of other neurons or with the body’s muscles and glands.

Neuron by sculptor Roxy Paine

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“What one neuron tells another neuron is simply how much it is excited.”

Francis Crick, The Astonishing Hypothesis, 1994

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38 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

1. Neuron stimulation causes a brief change in electrical charge. If strong enough, this produces depolarization and an action potential.

2. This depolarization produces another action potential a little farther along the axon. Gates in this neighboring area now open, and charged sodium atoms rush in. A pump in the cell membrane (the sodium/potassium pump) transports the sodium ions back out of the cell.

3. As the action potential continues speedily down the axon, the first section has now completely recharged.

Cell body end of axon

Direction of action potential: toward axon terminals

Increasing the level of stimulation above the threshold will not increase the neural impulse’s intensity. The neuron’s reaction is an all-or-none response: Like guns, neurons either fire or they don’t. How, then, do we detect the intensity of a stimulus? How do we distinguish a gentle touch from a big hug? A strong stimulus can trigger more neurons to fire, and to fire more often. But it does not affect the action potential’s strength or speed. Squeezing a trigger harder won’t make a bullet go faster.

RETRIEVE IT

• When a neuron fires an action potential, the information travels through the axon, the dendrites, and the axon’s terminal branches, but not in that order. Place these three structures in the correct order.

ANSWER: dendrites, axon, axon’s terminal branches

• How does our nervous system allow us to experience the difference between a slap and a tap on the back?

ANSWER: Stronger stimuli (the slap) cause more neurons to fire and to fire more frequently than happens with weaker stimuli (the tap).

How Neurons Communicate

2-3: How do nerve cells communicate with other nerve cells?

Neurons interweave so intricately that even with a microscope you would have trouble seeing where one neuron ends and another begins. Scientists

once believed that the axon of one cell fused with the dendrites of another in an unin- terrupted fabric. Then British physiologist Sir Charles Sherrington (1857–1952) noticed that neural impulses were taking an unexpectedly long time to travel a neural pathway.

FIGURE 2.2

Action potential

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 39

Inferring that there must be a brief interruption in the transmission, Sherrington called the meeting point between neurons a synapse.

We now know that the axon terminal of one neuron is in fact separated from the receiving neuron by a synaptic gap (or synaptic cleft) less than a millionth of an inch wide. Spanish anatomist Santiago Ramón y Cajal (1852–1934) marveled at these near-unions of neurons, calling them “protoplasmic kisses.” “Like elegant ladies air- kissing so as not to muss their makeup, dendrites and axons don’t quite touch,” noted poet Diane Ackerman (2004). How do the neurons execute this protoplasmic kiss, sending information across the tiny synaptic gap? The answer is one of the important scientific discoveries of our age.

When an action potential reaches the knob-like terminals at an axon’s end, it trig- gers the release of chemical messengers, called neurotransmitters (FIGURE 2.3). Within 1/10,000th of a second, the neurotransmitter molecules cross the synaptic gap and bind to receptor sites on the receiving neuron—as precisely as a key fits a lock. For an instant, the neurotransmitter unlocks tiny channels at the receiving site, and electrically charged atoms flow in, exciting or inhibiting the receiving neuron’s readi- ness to fire. Then, in a process called reuptake, the sending neuron reabsorbs the excess neurotransmitters from the synapse.

RETRIEVE IT

• What happens in the synaptic gap?

ANSWER: Neurons send neurotransmitters (chemical messengers) across this tiny space between one neuron’s terminal branch and the next neuron’s dendrite or cell body.

“All information processing in the brain involves neurons ‘talking to’ each other at synapses.”

Neuroscientist Solomon H. Snyder (1984)

Receiving neuron

Sending neuron

1. Electrical impulses (action potentials) travel down a neuron’s axon until reaching a tiny junction known as a synapse.

3. The sending neuron normally reabsorbs excess neurotransmitter molecules, a process called reuptake.

Sending neuron

Action potential

Axon terminal

NeurotransmitterReceptor sites on receiving neuron

Synaptic gap

Action potential

Reuptake

2. When an action potential reaches an axon terminal, it stimulates the release of neurotransmitter molecules. These molecules cross the synaptic gap and bind to receptor sites on the receiving neuron. This allows electrically charged atoms to enter the receiving neuron and excite or inhibit a new action potential.

Synapse

FIGURE 2.3

How neurons communicate

synapse [SIN-aps] the junction between the a xon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.

neurotransmitters chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neu- rotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

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40 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

How Neurotransmitters Influence Us

2-4: How do neurotransmitters influence behavior?

In their quest to understand neural communication, researchers have discovered dozens of different neurotransmitters and almost as many new questions: Are cer-

tain neurotransmitters found only in specific places? How do they affect our moods, memo- ries, and mental abilities? Can we boost or diminish these effects through drugs or diet?

Later chapters explore neurotransmitter influences on hunger and thinking, depres- sion and euphoria, addictions and therapy. For now, let’s glimpse how neurotransmitters influence our motions and emotions. A particular neurotransmitter may affect specific behaviors and emotions (TABLE 2.1), and a particular brain pathway may use only one or two neurotransmitters (FIGURE 2.4).

Acetylcholine (ACh), which plays a role in learning and memory, is one of the best-understood neurotransmitters. In addition, it is the messenger at every junction between motor neurons (which carry information from the brain and spinal cord to the body’s tissues) and skeletal muscles. When ACh is released to our muscle cell receptors, the muscle contracts. If ACh transmission is blocked, as happens during some kinds of anesthesia, the muscles cannot contract and we are paralyzed.

Candace Pert and Solomon Snyder (1973) made an exciting discovery about neu- rotransmitters when they attached a radioactive tracer to morphine, showing where it was taken up in an animal’s brain. The morphine, an opiate drug that elevates mood and eases pain, bound to receptors in areas linked with mood and pain sensations. But why would the brain have these “opiate receptors”? Why would it have a chemical lock, unless it also had a natural key to open it?

Researchers soon confirmed that the brain does indeed produce its own naturally occurring opiates. Our body releases several types of neurotransmitter molecules similar to morphine in response to pain and vigorous exercise. These endorphins (short for endogenous [produced within] morphine) help explain good feelings such as the “run- ner’s high,” the painkilling effects of acupuncture, and the indifference to pain in some severely injured people.

LiquidLibrary/Jupiterimages

Table 2.1

Some Neurotransmitters and Their Functions

Neurotransmitter Function Examples of Malfunctions

Acetylcholine (ACh)

Enables muscle action, learn- ing, and memory.

With Alzheimer’s disease, ACh - producing neu- rons deteriorate.

Dopamine Influences movement, learn- ing, attention, and emotion.

Oversupply linked to schizophrenia. Undersup- ply linked to tremors and decreased mobility in Parkinson’s disease.

Serotonin Affects mood, hunger, sleep, and arousal.

Undersupply linked to depression. Some antide- pressant drugs raise serotonin levels.

Norepinephrine Helps control alertness and arousal.

Undersupply can depress mood.

GABA (gamma - aminobutyric acid)

A major inhibitory neurotransmitter.

Undersupply linked to seizures, tremors, and insomnia.

Glutamate A major excitatory neu- rotransmitter; involved in memory.

Oversupply can overstimulate brain, producing migraines or seizures (which is why some people avoid MSG, monosodium glutamate, in food).

SomSom

“When it comes to the brain, if you want to see the action, follow the neurotransmitters.”

Neuroscientist Floyd Bloom (1993)

Physician Lewis Thomas, on the endorphins: “There it is, a biologically universal act of mercy. I cannot explain it, except to say that I would have put it in had I been around at the very beginning, sitting as a member of a planning committee.”

The Youngest Science, 1983

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 41

Serotonin pathways Dopamine pathways

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If indeed the endorphins lessen pain and boost mood, why not flood the brain with artificial opiates, thereby intensifying the brain’s own “feel-good” chemistry? One problem is that when flooded with opiate drugs such as heroin and morphine, the brain may stop producing its own natural opiates. When the drug is withdrawn, the brain may then be deprived of any form of opiate, causing intense discomfort. For suppressing the body’s own neurotransmitter production, nature charges a price.

RETRIEVE IT

• The endorphins, serotonin, and dopamine are all chemical messengers called

. ANSWER: neurotransmitters

The Nervous System 2-5: What are the functions of the nervous system’s main divisions, and what are the three main types of neurons?

To live is to take in information from the world and the body’s tissues, to make decisions, and to send back information and orders to the body’s tissues. All this happens thanks to our body’s nervous system (FIGURE 2.5 on the next page). The brain and spinal cord form the central nervous system (CNS), the body’s decision maker. The peripheral nervous system (PNS) is responsible for gather- ing information and for transmitting CNS decisions to other body parts. Nerves, electrical cables formed of bundles of axons, link the CNS with the body’s sensory receptors, muscles, and glands. The optic nerve, for example, bundles a million axons into a single cable carrying the messages each eye sends to the brain (Mason & Kandel, 1991).

Information travels in the nervous system through three types of neurons. Sensory neurons carry messages from the body’s tissues and sensory receptors inward to the brain and spinal cord for processing. Motor neurons carry instructions from the cen- tral nervous system out to the body’s muscles. Between the sensory input and motor output, information is processed via the brain’s interneurons. Our complexity resides mostly in our interneuron systems. Our nervous system has a few million sensory neu- rons, a few million motor neurons, and billions and billions of interneurons.

endorphins [en - DOR-fins] “morphine within”—natural, opiate-like neurotransmitters linked to pain control and to pleasure.

nervous system the body’s speedy, elec- trochemical communication network, consisting of all the nerve cells of the peripheral and cen- tral nervous systems.

central nervous system (CNS) the brain and spinal cord.

peripheral nervous system (PNS) the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

nerves bundled axons that form neural “cables” connecting the central nervous system with muscles, glands, and sense organs.

sensory (afferent) neurons neurons that carry incoming information from the sen- sory receptors to the brain and spinal cord.

motor (efferent) neurons neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.

interneurons neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs.

FIGURE 2.4

Neurotransmitter pathways Each of the brain’s differing chemical messengers has designated pathways where it operates, as shown here for serotonin and dopamine (Carter, 1998).

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42 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

The Peripheral Nervous System Our peripheral nervous system has two components—somatic and autonomic. Our somatic nervous system enables voluntary control of our skeletal muscles (and is also called the skeletal nervous system). As you reach the bottom of the next page, your somatic nervous system will report to your brain the current state of your skeletal muscles and carry instructions back, triggering your hand to turn the page.

Our autonomic nervous system (ANS) controls our glands and the muscles of our internal organs, influencing such functions as glandular activity, heartbeat, and diges- tion. (Autonomic means “self-regulating.”) Like an automatic pilot, this system may be consciously overridden, but usually it operates on its own (autonomously).

The autonomic nervous system serves two important, basic functions (FIGURE 2.6). The sympathetic nervous system arouses and expends energy. If something alarms or challenges you (such as a longed-for job interview), your sympathetic nervous system will accelerate your heartbeat, raise your blood pressure, slow your digestion, raise your blood sugar, and cool you with perspiration, making you alert and ready for action. When the stress subsides (the interview is over), your parasympathetic nervous system will produce the opposite effects, conserving energy as it calms you by decreasing your heartbeat, lowering your blood sugar, and so forth. In everyday situations, the sympathetic and parasympathetic nervous systems work together to keep you in a steady internal state called homeostasis (more on this in Chapter 10).

I recently experienced my ANS in action. Before sending me into an MRI machine for a routine shoulder scan, the technician asked if I had issues with claustrophobia. “No, I’m fine,” I assured her, with perhaps a hint of macho swagger. Moments later, as I found myself on my back, stuck deep inside a coffin-sized box and unable to move, my sympathetic nervous system had a different idea. As claustrophobia overtook me, my heart began pounding and I felt a desperate urge to escape. Just as I was about to cry out for release, I felt my calming parasympathetic nervous system kick in. My heart rate slowed and my body relaxed, though my arousal surged again before the 20-minute confinement ended. “You did well!” the technician said, unaware of my ANS roller-coaster ride.

Autonomic (controls self-regulated action

of internal organs and glands)

Somatic (controls voluntary

movements of skeletal muscles)

Sympathetic (arousing)

Parasympathetic (calming)

Peripheral Central

(brain and spinal cord)

Nervous system

Peripheral nervous system Central nervous system

somatic nervous system the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skel- etal nervous system.

autonomic [aw - tuh - NAHM-ik] nervous system (ANS) the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

sympathetic nervous system the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.

parasympathetic nervous system the division of the autonomic nervous system that calms the body, conserving its energy.

FIGURE 2.5

The functional divisions of the

human nervous system

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 43

SYMPATHETIC NERVOUS SYSTEM

(arousing)

PARASYMPATHETIC NERVOUS SYSTEM

(calming) Brain

Dilates pupils

Contracts pupils

Slows heartbeat

Spinal cord

Stimulates digestion

Stimulates gallbladder

Contracts bladder

Allows blood flow to sex organs

Heart Accelerates heartbeat

Stomach Inhibits digestion

Pancreas

Liver

Adrenal gland

Kidney

Relaxes bladder

Stimulates ejaculation in male

Stimulates secretion of epinephrine, norepinephrine

Stimulates glucose release by liver

RETRIEVE IT

• Match the type of neuron to its description.

Type Description

1. Motor neurons a. carry incoming messages from sensory receptors to the CNS.

2. Sensory neurons b. communicate within the CNS and intervene between incoming and outgoing messages.

3. Interneurons c. carry outgoing messages from the CNS to muscles and glands.

ANSWERS: 1. c, 2. a, 3. b

• What bodily changes does your autonomic nervous system (ANS) direct before and after you give an important speech?

ANSWER: Responding to this challenge, your ANS’ sympathetic division will arouse you. It accelerates your heartbeat, raises your blood pressure and blood sugar, slows your digestion, and cools you with perspiration. After you give the speech, your ANS’ parasympathetic division will reverse these effects.

FIGURE 2.6

The dual functions of the autonomic

nervous system The autonomic nervous system controls the more autonomous (or self - regulating) internal functions. Its sympathetic division arouses and expends energy. Its parasympathetic division calms and conserves energy, allowing routine maintenance activity. For example, sympathetic stimulation accelerates heartbeat, whereas parasympathetic stimulation slows it.

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44 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

The Central Nervous System From the simplicity of neurons “talking” to other neurons arises the complexity of the central nervous system’s brain and spinal cord.

It is the brain that enables our humanity—our thinking, feeling, and acting. Tens of billions of neurons, each communicating with thousands of other neurons, yield an ever- changing wiring diagram. With some 40 billion neurons, each connecting with roughly 10,000 other neurons, we end up with perhaps 400 trillion synapses—places where neurons meet and greet their neighbors (de Courten-Myers, 2005).1

The brain’s neurons cluster into work groups called neural networks. To understand why, Stephen Kosslyn and Olivier Koenig (1992, p. 12) have invited us to “think about why cities exist; why don’t people distribute themselves more evenly across the coun- tryside?” Like people networking with people, neurons network with nearby neurons with which they can have short, fast connections.

The other part of the CNS, the spinal cord, is a two-way information highway con- necting the peripheral nervous system and the brain. Ascending neural fibers send up sensory information, and descending fibers send back motor-control information. The neural pathways governing our reflexes, our automatic responses to stimuli, illustrate the spinal cord’s work. A simple spinal reflex pathway is composed of a single sensory neuron and a single motor neuron. These often communicate through an interneuron. The knee-jerk response, for example, involves one such simple pathway. A headless warm body could do it.

Another neural circuit enables the pain reflex (FIGURE 2.7). When your finger touches a flame, neural activity (excited by the heat) travels via sensory neurons to inter- neurons in your spinal cord. These interneurons respond by activating motor neurons leading to the muscles in your arm. Because the simple pain-reflex circuit runs through the spinal cord and right back out, your hand jerks away from the candle’s flame before your brain receives and responds to the information that causes you to feel pain. That’s why it feels as if your hand jerks away not by your choice, but on its own.

“The body is made up of millions and millions of crumbs.”

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1. In this simple hand-withdrawal reflex, information is carried from skin receptors along a sensory neuron (shown by the large red arrow) to the spinal cord. From there it is passed via interneurons to motor neurons (blue arrow) that lead to the muscles in the hand and arm.

Brain

Muscle

Skin receptors

Motor neuron (outgoing information)

Sensory neuron (incoming information)

Spinal cord

Interneuron

2. Because this reflex involves only the spinal cord, the hand jerks away from the candle flame even before information about the event has reached the brain, causing the experience of pain.

1 Another research team, projecting from representative tissue samples, has estimated that the adult human male brain contains 86 billion neurons—give or take 8 billion (Azevedo et al., 2009). One moral: Distrust big round numbers, such as the familiar, undocumented claim that the human brain contains 100 billion neurons.

reflex a simple, automatic response to a sen- sory stimulus, such as the knee - jerk response.

endocrine [EN-duh - krin] system the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.

hormones chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

adrenal [ah - DREEN-el] glands a pair of endocrine glands that sit just above the kid- neys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

pituitary gland the endocrine system’s most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

FIGURE 2.7

A simple reflex

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 45

Information travels to and from the brain by way of the spinal cord. Were the top of your spinal cord severed, you would not feel pain from your body below. Nor would you feel pleasure. With your brain literally out of touch with your body, you would lose all sensation and voluntary movement in body regions with sensory and motor connec- tions to the spinal cord below its point of injury. You would exhibit the knee jerk with- out feeling the tap. When the brain center keeping the brakes on erections is severed, men paralyzed below the waist may be capable of an erection (a simple reflex) if their genitals are stimulated (Goldstein, 2000). Women similarly paralyzed may respond with vaginal lubrication. But, depending on where and how completely the spinal cord is severed, they may be genitally unresponsive to erotic images and have no genital feeling (Kennedy & Over, 1990; Sipski & Alexander, 1999). To produce bodily pain or pleasure, the sensory information must reach the brain.

The Endocrine System 2-6: How does the endocrine system transmit information and interact with the nervous system?

So far, we have focused on the body’s speedy electrochemical information sys- tem. Interconnected with your nervous system is a second communication system, the endocrine system (FIGURE 2.8). The endocrine system’s glands secrete another form of chemical messengers, hormones, which travel through the bloodstream and affect other tissues, including the brain. When hormones act on the brain, they influence our interest in sex, food, and aggression.

Some hormones are chemically identical to neurotransmitters (the chemical messengers that diffuse across a synapse and excite or inhibit an adjacent neuron). The endocrine system and nervous system are therefore close relatives: Both produce molecules that act on recep- tors elsewhere. Like many relatives, they also differ. The speedy nervous system zips messages from eyes to brain to hand in a fraction of a second. Endocrine messages trudge along in the bloodstream, taking several seconds or more to travel from the gland to the target tissue. If the nervous system delivers information to a specific receptor site with the speed of a text message, the endocrine system is more like a snail-mail bulk mailing.

Endocrine messages tend to outlast the effects of neural mes- sages. That helps explain why upset feelings may linger beyond our awareness of what upset us. When this happens, it takes time for us to “simmer down.” In a moment of danger, for example, the ANS orders the adrenal glands on top of the kidneys to release epinephrine and norepinephrine (also called adrenaline and noradrenaline). These hormones increase heart rate, blood pres- sure, and blood sugar, providing a surge of energy. When the emergency passes, the hormones—and the feelings of excite- ment—linger a while.

The most influential endocrine gland is the pituitary gland, a pea-sized structure located in the core of the brain, where it is controlled by an adjacent brain area, the hypothalamus (more on that shortly). Among the hormones released by the pituitary is a growth hormone that stimulates physical development. Another is oxytocin, which enables contractions associated with birthing, milk flow during nursing, and orgasm. Oxytocin also promotes pair bonding, group cohesion, and social trust (De Dreu et al., 2010). During a laboratory game, those given a nasal squirt of oxytocin rather than a placebo were more likely to trust strang- ers with their money (Kosfeld et al., 2005).

Hypothalamus (brain region controlling

the pituitary gland)

Thyroid gland (affects metabolism)

Pituitary gland (secretes many different hormones, some of which affect other glands)

Parathyroids (help regulate the level of calcium in the blood)

Adrenal glands (inner part helps

trigger the “fight-or-flight”

response) Pancreas (regulates the level of sugar in the blood)

Ovary (secretes female sex hormones)

Testis (secretes male sex

hormones)

“If the nervous system be cut off between the brain and other parts, the experiences of those other parts are nonexistent for the mind. The eye is blind, the ear deaf, the hand insensible and motionless.”

William James, Principles of Psychology, 1890

FIGURE 2.8

The endocrine system

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46 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

“I am a brain, Watson. The rest of me is a mere appendix.”

Sherlock Holmes, in Arthur Conan Doyle’s “The Adventure of the

Mazarin Stone”

lesion [LEE-zhuhn] tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue.

brainstem the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions.

medulla [muh - DUL-uh] the base of the brain- stem; controls heartbeat and breathing.

Pituitary secretions also influence the release of hormones by other endocrine glands. The pituitary, then, is a master gland (whose own master is the hypothalamus). For example, under the brain’s influence, the pituitary triggers your sex glands to release sex hormones. These in turn influence your brain and behavior.

This feedback system (brain → pituitary → other glands → hormones → body and brain) reveals the intimate connection of the nervous and endocrine systems. The nervous system directs endocrine secretions, which then affect the nervous system. Conducting and coordinating this whole electrochemical orchestra is that maestro we call the brain.

RETRIEVE IT

• Why is the pituitary gland called the “master gland”?

ANSWER: Responding to signals from the hypothalamus, the pituitary releases hormones that trigger other endocrine glands to secrete hormones, which in turn influence our brain and our behavior.

• How are the nervous and endocrine systems alike, and how do they differ?

ANSWER: Both of these communication systems produce chemical molecules that act on the body’s receptors to influence our behavior and emotions. The endocrine system, which secretes hormones into the bloodstream, delivers its messages much more slowly than the speedy nervous system, and the effects of the endocrine system’s messages tend to linger much longer than those of the nervous system.

The Brain 2-7: How do neuroscientists study the brain’s connections to behavior and mind?

The mind seeking to understand the brain—that is indeed among the ulti- mate scientific challenges. And so it will always be. To paraphrase cosmologist John Bar- row, a brain simple enough to be understood is too simple to produce a mind able to understand it.

When you think about your brain, you’re thinking with your brain—sending billions of neurotransmitter molecules across countless millions of synapses. Indeed, say neuro- scientists, “the mind is what the brain does” (Minsky, 1986).

A century ago, scientists had no tools high powered yet gentle enough to reveal a living brain’s activity. Clinical observations had unveiled some brain-mind connections. Physicians had noted that damage to one side of the brain often caused numbness or paralysis on the opposite side, suggesting that the body’s right side is wired to the brain’s left side, and vice versa. Others noticed that damage to the back of the brain disrupted vision, and that damage to the left-front part of the brain produced speech difficulties. Gradually, these early explorers were mapping the brain.

Now, within a lifetime, the whole brain-mapping process has changed. The known universe’s most amazing organ is being probed and mapped by a new generation of neural mapmakers. Whether in the interests of science or medicine, they can selectively lesion (destroy) tiny clusters of normal or defective brain cells, leaving the surrounding tissue unharmed. Today’s scientists can snoop on the messages of individual neurons, using mod- ern microelectrodes with tips small enough to detect the electrical pulse in a single neu- ron. For example, they can now detect exactly where the information goes in a cat’s brain when someone strokes its whisker. They can also stimulate various brain parts—electrically, chemically, or magnetically—and note the effects; eavesdrop on the chatter of billions of neurons; and see color representations of the brain’s energy-consuming activity.

These techniques for peering into the thinking, feeling brain are doing for psychol- ogy what the microscope did for biology and the telescope did for astronomy. Close-Up: The Tools of Discovery on the next page looks at some techniques that enable neuro- scientists to study the working brain.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 47

American Images Inc/Getty Images

Thalamus

Reticular formation

Pons

Medulla

Brainstem

Older Brain Structures

2-8: What structures make up the brainstem, and what are the functions of the brainstem, thalamus, and cerebellum?

An animal’s capacities come from its brain structures. In primitive animals, such as sharks, a not-so-complex brain primarily regulates basic survival functions: breathing, resting, and feeding. In lower mammals, such as rodents, a more complex brain enables emotion and greater memory. In advanced mammals, such as humans, a brain that processes more information enables increased foresight as well.

This increasing complexity arises from new brain systems built on top of the old, much as the Earth’s landscape covers the old with the new. Digging down, one discovers the fossil remnants of the past—brainstem components performing for us much as they did for our distant ancestors. Let’s start with the brain’s basement and work up to the newer systems.

The Brainstem The brain’s oldest and innermost region is the brainstem. It begins where the spinal cord swells slightly after entering the skull. This slight swelling is the medulla (FIGURE 2.9). Here lie the controls for your heartbeat and breathing. As brain-damaged patients in a vegetative state illustrate, we need no higher brain or conscious mind to orchestrate our heart’s pumping and lungs’ breathing. The brainstem handles those tasks. Just above the medulla sits the pons, which helps coordinate movements.

If a cat’s brainstem is severed from the rest of the brain above it, the animal will still breathe and live—and even run, climb, and groom (Klemm, 1990). But cut off from the brain’s higher regions, it won’t purposefully run or climb to get food.

FIGURE 2.9

The brainstem and thalamus The brainstem, including the pons and medulla, is an extension of the spinal cord. The thalamus is attached to the top of the brainstem. The reticular formation passes through both structures.

FIGURE 2.10

The body’s wiring

The brainstem is a crossover point, where most nerves to and from each side of the brain connect with the body’s opposite side (FIGURE 2.10). This peculiar cross-wiring is but one of the brain’s many surprises.

RETRIEVE IT

• Nerves from the left side of the brain are mostly linked to the

side of the body, and vice versa.

ANSWER: right

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The Thalamus Sitting atop the brainstem is the thalamus, a pair of egg-shaped structures that act as the brain’s sensory router (Figure 2.9). The thalamus receives information from all the senses except smell, and it routes that information to higher brain regions that deal with see- ing, hearing, tasting, and touching. The thalamus also receives some of the higher brain’s replies, which it then directs to the medulla and to the cerebellum (see the next page). Think of the thalamus as being to sensory information what London is to England’s trains: a hub through which traffic passes en route to various destinations.

The Tools of Discovery—Having Our Head Examined

CLOSE UP:

“You must look into people, as well as at them,” advised Lord Chesterfield in a 1746 let- ter to his son. Unlike EEGs, newer neuroim- aging techniques give us that Superman-like ability to see inside the living brain. One such tool, the PET (positron emission tomography) scan (FIGURE 2.12), depicts brain activity by showing each brain area’s consumption of its chemical fuel, the sugar glucose. Active neurons are glucose hogs, and after a person receives temporarily radioactive glucose, the PET scan can track the gamma rays released by this “food for thought” as the person performs a given task. Rather like weather radar showing rain activity, PET-scan “hot spots” show which brain areas are most active as the person does mathematical calculations, looks at images of faces, or daydreams.

In MRI (magnetic resonance imaging) brain scans, the person’s head is put in a strong mag- netic field, which aligns the spinning atoms of brain molecules. Then, a radio-wave pulse momentarily disorients the atoms. When the atoms return to their normal spin, they emit

signals that provide a detailed picture of soft tissues, including the brain. MRI scans have revealed a larger- than - average neural area in the left hemisphere of musicians who display perfect pitch (Schlaug et al., 1995). They have also revealed enlarged ventricles—fluid- filled brain areas (marked by the red arrows in FIG- URE 2.13)—in some patients who have schizo- phrenia, a disabling psychological disorder.

A special application of MRI—fMRI (functional MRI)—can reveal the brain’s func- tioning as well as its structure. Where the brain is especially active, blood goes. By compar- ing MRI scans taken less than a second apart, researchers can watch the brain activate (with increased oxygen - laden bloodflow) as a per- son performs different mental functions. As the person looks at a scene, for example, the fMRI machine detects blood rushing to the back of the brain, which processes visual information (see Figure 2.21, in the discussion of cortex functions).

Such snapshots of the brain’s chang- ing activity are providing new insights into

Minding minds Neuroscientists Hanna Damasio and Antonio Damasio explore how the brain makes mind.

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Right now, your mental activity is emitting telltale electrical, metabolic, and magnetic signals that would enable neuroscientists to observe your brain at work. Electrical activity in your brain’s billions of neurons sweeps in regular waves across its surface. An electro- encephalogram (EEG) is an amplified read out of such waves (FIGURE 2.11). Researchers record the brain waves through a shower-cap- like hat that is filled with electrodes covered with a conductive gel.

thalamus [THAL-uh - muss] the brain’s sen- sory router, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cer- ebellum and medulla.

48 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 49

The Reticular Formation Inside the brainstem, between your ears, lies the reticular (“net-like”) formation, a finger-shaped network of neurons extending from the spinal cord right up through the thalamus. As the spinal cord’s sensory input flows up to the thalamus, some of it travels through the reticular formation, which filters incoming stimuli, relays important infor- mation to other brain areas, and controls arousal.

In 1949, Giuseppe Moruzzi and Horace Magoun discovered that electrically stimu- lating a sleeping cat’s reticular formation almost instantly produced an awake, alert

how the brain divides its labor. A mountain of recent fMRI studies suggests which brain areas are most active when people feel pain or rejection, listen to angry voices, think about scary things, feel happy, or become sexu- ally excited. The technology enables a very crude sort of mind reading. After scanning 129 people’s brains as they did eight different mental tasks (such as reading, gambling, or rhyming), neuroscientists were able, with 80 percent accuracy, to predict which of these mental activities people were doing (Poldrack et al., 2009).

To be learning about the neurosciences now is like studying world geography while Magel- lan was exploring the seas. This truly is the golden age of brain science. FIGURE 2.13

MRI scan of a

healthy individual

(left) and a person

with schizophrenia

(right) Note the enlarged ventricle, the fluid- filled brain region at the tip of the arrow in the image on the right.

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RETRIEVE IT

• Match the scanning technique with the correct description.

Technique Description

1. fMRI scan a. tracks radioactive glucose to reveal brain activity.

2. PET scan b. tracks successive images of brain tissue to show brain function.

3. MRI scan c. uses magnetic fields and radio waves to show brain anatomy.

ANSWERS: 1. b, 2. a, 3. c

electroencephalogram (EEG) an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.

PET (positron emission tomogra- phy) scan a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.

MRI (magnetic resonance imaging) a technique that uses magnetic fields and radio waves to produce computer - generated images of soft tissue. MRI scans show brain anatomy.

fMRI (functional MRI) a technique for revealing bloodflow and, therefore, brain activ- ity by comparing successive MRI scans. fMRI scans show brain function.

FIGURE 2.12

The PET scan To obtain a PET scan, researchers inject volunteers with a low and harmless dose of a short - lived radioactive sugar. Detectors around the person’s head pick up the release of gamma rays from the sugar, which has concentrated in active brain areas. A computer then processes and translates these signals into a map of the brain at work.

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reticular formation a nerve network that travels through the brainstem and plays an important role in controlling arousal.

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50 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

FIGURE 2.14

The brain’s organ of

agility Hanging at the back of the brain, the cerebellum coordinates our voluntary movements.

Cerebellum

Spinal cord

Hypothalamus

Pituitary gland

Amygdala Hippocampus

animal. When Magoun severed a cat’s reticular formation without damaging nearby sen- sory pathways, the effect was equally dramatic: The cat lapsed into a coma from which it never awakened.

The Cerebellum Extending from the rear of the brainstem is the baseball-sized cerebellum, meaning “little brain,” which is what its two wrinkled halves resemble (FIGURE 2.14). As you will see in Chapter 8, the cerebellum enables nonverbal learning and memory. It also

helps us judge time, modulate our emotions, and discrimi- nate sounds and textures (Bower & Parsons, 2003). And it coordinates voluntary movement. When a soccer player executes a perfect bicycle kick, give his cerebellum some

credit. Under alcohol’s influence on the cerebellum, coordina- tion suffers. And if you injured your cerebellum, you would have difficulty

walking, keeping your balance, or shaking hands. Your movements would be jerky and exaggerated. Gone would be any dreams of being

a dancer or guitarist.

* * * Note: These older brain functions all occur without any

conscious effort. This illustrates another of our recurring themes: Our brain processes most information outside of our aware-

ness. We are aware of the results of our brain’s labor (say, our current visual experience) but not of how we construct the visual

image. Likewise, whether we are asleep or awake, our brainstem manages its life-sustaining functions, freeing our newer brain regions to think, talk, dream, or savor a memory.

RETRIEVE IT

• In what brain region would damage be most likely to (1) disrupt your ability to skip rope? (2) disrupt your ability to hear and taste? (3) perhaps leave you in a coma? (4) cut off the very breath and heartbeat of life?

ANSWERS: 1. cerebellum, 2. thalamus, 3. reticular formation, 4. medulla

The Limbic System

2-9: What are the limbic system’s structures and functions?

We’ve considered the brain’s oldest parts, but we’ve not yet reached its new- est and highest regions, the cerebral hemispheres (the two halves of the brain).

Between the oldest and newest brain areas lies the limbic system (limbus means “bor- der”). This system contains the amygdala, the hypothalamus, and the hippocampus (FIGURE 2.15). The hippocampus processes conscious memories. Animals or humans who lose their hippocampus to surgery or injury also lose their ability to form new memories of facts and events. Chapter 8 explains how our two-track mind processes our memories. For now, let’s look at the limbic system’s links to emotions such as fear and anger, and to basic motives such as those for food and sex.

The Amygdala Research has linked the amygdala, two lima-bean-sized neural clus- ters, to aggression and fear. In 1939, psychologist Heinrich Klüver and neurosurgeon Paul Bucy surgically removed a rhesus monkey’s amygdala, turning the normally ill- tempered animal into the most mellow of creatures.

What then might happen if we electrically stimulated the amygdala of a normally placid domestic animal, such as a cat? Do so in one spot and the cat prepares to attack,

Ryan McVay/Getty Images

FIGURE 2.15

The limbic system This neural system sits between the brain’s older parts and its cerebral hemispheres. The limbic system’s hypothalamus controls the nearby pituitary gland.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 51

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cerebellum [sehr - uh - BELL-um] the “little brain” at the rear of the brainstem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory.

limbic system neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associ- ated with emotions and drives.

amygdala [uh - MIG-duh - la] two lima-bean- sized neural clusters in the limbic system; linked to emotion.

hypothalamus [hi - po - THAL-uh- muss] a neural structure lying below (hypo) the thala- mus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

hissing with its back arched, its pupils dilated, its hair on end. Move the electrode only slightly within the amyg- dala, cage the cat with a small mouse, and now it cowers in terror.

These and other experiments have confirmed the amygdala’s role in rage and fear, including the percep- tion of these emotions and the processing of emotional memories (Anderson & Phelps, 2000; Poremba & Gabriel, 2001). But we must be careful. The brain is not neatly organized into structures that correspond to our behavior categories. When we feel or act in aggressive or fearful ways, there is neural activity in many areas of our brain. Even within the limbic system, stimulating structures other than the amygdala can evoke aggression or fear. If you charge a car’s dead battery, you can activate the engine. Yet the battery is merely one link in an integrated system.

RETRIEVE IT

• Electrical stimulation of a cat’s amygdala provokes angry reactions, suggesting the amygdala’s role in aggression. Which ANS division is activated by such stimulation?

ANSWER: The sympathetic nervous system

The Hypothalamus Just below (hypo) the thalamus is the hypothalamus (FIGURE 2.16), an important link in the command chain governing bodily maintenance. Some neu- ral clusters in the hypothalamus influence hunger; others regulate thirst, body temperature, and sexual behavior. Together, they help maintain a steady (homeostatic) internal state.

As the hypothalamus monitors the state of your body, it tunes into your blood chem- istry and any incoming orders from other brain parts. For example, picking up signals from your brain’s cerebral cortex that you are thinking about sex, your hypothalamus will secrete hormones. These hormones will in turn trigger the adjacent “master gland,” your pituitary (see Figure 2.15), to influence your sex glands to release their hormones. These will intensify the thoughts of sex in your cerebral cortex. (Once again, we see the interplay between the nervous and endocrine systems: The brain influences the endo- crine system, which in turn influences the brain.)

A remarkable discovery about the hypothalamus illustrates how progress in science often occurs—when curious, open-minded investigators make an unexpected observa- tion. Two young McGill University neuropsychologists, James Olds and Peter Milner (1954), were trying to implant an electrode in a rat’s reticular formation when they made a magnificent mistake: They placed the electrode incorrectly (Olds, 1975). Curi- ously, as if seeking more stimulation, the rat kept returning to the location where it had been stimulated by this misplaced electrode. On discovering that they had actually placed the device in a region of the hypothalamus, Olds and Milner realized they had stumbled upon a brain center that provides pleasurable rewards (Olds, 1975).

In a meticulous series of experiments, Olds (1958) went on to locate other “pleasure centers,” as he called them. (What the rats actually experience only they know, and they aren’t telling. Rather than attribute human feelings to rats, today’s scientists refer to reward centers, not “pleasure centers.”) When allowed to press pedals to trigger their own stimulation in these areas, rats would sometimes do so at a feverish pace—up to 7000 times per hour—until they dropped from exhaustion. Moreover, to get this stimulation, they would even cross an electrified floor that a starving rat would not cross to reach food (FIGURE 2.17 on the next page).

Researchers later discovered other limbic system reward centers, such as the nucleus accumbens in front of the hypothalamus, in many other species, including dolphins and monkeys. In fact, animal research has revealed both a general dopamine-related reward system and specific centers associated with the pleasures of eating, drinking, and sex.

Jane Burton/Dorling Kindersley/Getty Images

FIGURE 2.16

The hypothalamus This small but important structure, colored yellow/orange in this MRI-scan photograph, helps keep the body’s internal environment in a steady state.

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52 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Animals, it seems, come equipped with built-in systems that reward activities essential to survival.

Do humans have limbic centers for pleasure? Indeed we do. To calm violent patients, one neurosurgeon implanted electrodes in such areas. Stimulated patients reported mild pleasure; unlike Olds’ rats, however, they were not driven to a frenzy (Deutsch, 1972; Hooper & Teresi, 1986).

Some researchers believe that addictive disorders, such as alcohol dependence, drug abuse, and binge eating, may stem from malfunctions in natural brain systems for plea- sure and well-being. People genetically predisposed to this reward deficiency syndrome may crave whatever provides that missing pleasure or relieves negative feelings (Blum et al., 1996).

* * * FIGURE 2.18 locates the brain areas we’ve discussed, as well as the cerebral cortex, our next topic.

“If you were designing a robot vehicle to walk into the future and survive, . . . you’d wire it up so that behavior that ensured the survival of the self or the species—like sex and eating—would be naturally reinforcing.”

Candace Pert (1986)

Stimulation pedal Electrified grid

FIGURE 2.17

Rat with an implanted electrode With an electrode implanted in a reward center of its hypothalamus, the rat readily crosses an electrified grid, accepting the painful shocks, to press a pedal that sends electrical impulses to that center.

Left hemisphere Right hemisphere

Corpus callosum: axon fibers connecting the two cerebral hemispheres

Thalamus: relays messages between lower brain centers and cerebral cortex

Pituitary: master endocrine gland

Cerebellum: coordinates voluntary movement and balance and supports memories of such

Cerebral cortex Limbic system Brainstem

Cerebral cortex: ultimate control and information-processing center

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Hypothalamus: controls maintenance functions such as eating; helps govern endocrine system; linked to emotion and reward

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Reticular formation: helps control arousal

Pons: helps coordinate movement

Medulla: controls heartbeat and breathing

Spinal cord: pathway for neural fibers traveling to and from brain; controls simple reflexes

Amygdala: linked to emotion

Hippocampus: linked to memory

x LLLimm

FIGURE 2.18

Review: Brain structures and their

functions

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 53

The people who first dissected and labeled the brain used the language of scholars—Latin and Greek. Their words are actually attempts at graphic description: For example, cortex means “bark,” cerebellum is “little brain,” and thalamus is “inner chamber.”

Frontal lobe Parietal lobe

Occipital lobe

The brain has left and right hemispheres

Temporal lobe

cerebral [seh - REE-bruhl] cortex the intri- cate fabric of interconnected neural cells cover- ing the cerebral hemispheres; the body’s ultimate control and information - processing center.

frontal lobes portion of the cerebral cortex lying just behind the forehead; in volved in speaking and muscle movements and in making plans and judgments.

parietal [puh - RYE-uh - tuhl] lobes portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.

occipital [ahk - SIP-uh - tuhl] lobes portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.

temporal lobes portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.

RETRIEVE IT

• What are the three key structures of the limbic system, and what functions do they serve?

ANSWER: (1) The amygdala is involved in aggression and fear responses. (2) The hypothalamus is involved in bodily maintenance, pleasurable rewards, and control of the hormonal systems. (3) The hippocampus processes memory.

The Cerebral Cortex

2-10: What are the functions of the various cerebral cortex regions?

Older brain networks sustain basic life functions and enable memory, emotions, and basic drives. Newer neural networks within the cerebrum—the two cerebral hemispheres contributing 85 percent of the brain’s weight—form special- ized work teams that enable our perceiving, thinking, and speaking. Like other structures above the brainstem (including the thalamus, hippocampus, and amyg- dala), the cerebral hemispheres come as a pair. Covering those hemispheres, like bark on a tree, is the cerebral cortex, a thin surface layer of interconnected neural cells. It is your brain’s thinking crown, your body’s ultimate control and informa- tion-processing center.

As we move up the ladder of animal life, the cerebral cortex expands, tight genetic controls relax, and the organism’s adaptability increases. Frogs and other small-cortex amphibians operate extensively on preprogrammed genetic instructions. The larger cor- tex of mammals offers increased capacities for learning and thinking, enabling them to be more adaptable. What makes us distinctively human mostly arises from the complex functions of our cerebral cortex.

RETRIEVE IT

• Which area of the human brain is most similar to that of less complex animals? Which part of the human brain distinguishes us most from less complex animals?

ANSWERS: The brainstem; the cerebral cortex

Structure of the Cortex If you opened a human skull, exposing the brain, you would see a wrinkled organ, shaped somewhat like the meat of an oversized walnut. Without these wrinkles, a flat- tened cerebral cortex would require triple the area—roughly that of a large pizza. The brain’s ballooning left and right hemispheres are filled mainly with axons connecting the cortex to the brain’s other regions. The cerebral cortex—that thin surface layer—contains some 20 to 23 billion nerve cells and 300 trillion synaptic connections (de Courten-Myers, 2005). Being human takes a lot of nerve.

Each hemisphere’s cortex is subdivided into four lobes, separated by prominent fissures, or folds (FIGURE 2.19). Starting at the front of your brain and moving over the top, there are the frontal lobes (behind your forehead), the parietal lobes (at the top and to the rear), and the occipital lobes (at the back of your head). Reversing direction and moving forward, just above your ears, you find the temporal lobes. Each of the four lobes car- ries out many functions, and many functions require the interplay of several lobes.

The brain has left and

FIGURE 2.19

The cortex and its basic subdivisions

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54 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Functions of the Cortex More than a century ago, surgeons found damaged cortical areas during autopsies of people who had been partially paralyzed or speechless. This rather crude evidence did not prove that specific parts of the cortex control complex functions like movement or speech. After all, if the entire cortex controlled speech and movement, damage to almost any area might produce the same effect. A TV with its power cord cut would go dead, but we would be fooling ourselves if we thought we had “localized” the picture in the cord.

Motor Functions Scientists had better luck in localizing simpler brain functions. For example, in 1870, German physicians Gustav Fritsch and Eduard Hitzig made an impor- tant discovery: Mild electrical stimulation to parts of an animal’s cortex made parts of its body move. The effects were selective: Stimulation caused movement only when applied to an arch-shaped region at the back of the frontal lobe, running roughly ear-to-ear across the top of the brain. Moreover, stimulating parts of this region in the left or right hemisphere caused movements of specific body parts on the opposite side of the body. Fritsch and Hitzig had discovered what is now called the motor cortex.

RETRIEVE IT

• Try moving your right hand in a circular motion, as if polishing a table. Then start your right foot doing the same motion, synchronized with your hand. Now reverse the right foot’s motion, but not the hand’s. Finally, try moving the left foot opposite to the right hand.

1. Why is reversing the right foot’s motion so hard?

2. Why is it easier to move the left foot opposite to the right hand?

ANSWERS: 1. The right limbs’ opposed activities interfere with each other because both are controlled by the same (left) side of your brain. 2. Opposite sides of your brain control your left and right limbs, so the reversed motion causes less interference.

MAPPING THE MOTOR CORTEX Lucky for brain surgeons and their patients, the brain has no sensory receptors. Knowing this, Otfrid Foerster and Wilder Penfield were able to map the motor cortex in hundreds of wide-awake patients by stimulat- ing different cortical areas and observing the body’s responses. They discovered that body areas requiring precise control, such as the fingers and mouth, occupy the greatest amount of cortical space (FIGURE 2.20).

In one of his many demonstrations of motor behavior mechanics, Spanish neuro- scientist José Delgado stimulated a spot on a patient’s left motor cortex, triggering the right hand to make a fist. Asked to keep the fingers open during the next stimulation, the patient, whose fingers closed despite his best efforts, remarked, “I guess, Doctor, that your electricity is stronger than my will” (Delgado, 1969, p. 114).

More recently, scientists were able to predict a monkey’s arm motion a tenth of a second before it moved—by repeatedly measuring motor cortex activity preceding specific arm movements (Gibbs, 1996). Such findings have opened the door to research on brain- controlled computers.

What might happen, some researchers are asking, if we implanted a device to detect motor cortex activity? Could such devices help severely paralyzed people learn to command a cursor to write e-mail or work online? Clinical trials are now under way with people who have suffered paralysis or amputation (Andersen et al., 2010; Nurmikko et al., 2010). The first patient, a paralyzed 25-year-old man, was able to mentally control a TV, draw shapes on a computer screen, and play video games—all thanks to an aspirin-sized chip with 100 microelectrodes recording activity in his motor cortex (Hochberg et al., 2006).

Sensory Functions If the motor cortex sends messages out to the body, where does the cortex receive incoming messages? Penfield identified a cortical area—at the front of the parietal lobes, parallel to and just behind the motor cortex—that specializes in receiving information from the skin senses and from the movement of body parts. We

motor cortex an area at the rear of the frontal lobes that controls voluntary movements.

sensory cortex area at the front of the parietal lobes that registers and processes body touch and movement sensations.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 55

now call this area the sensory cortex (Figure 2.20). Stimulate a point on the top of this band of tissue and a person may report being touched on the shoulder; stimulate some point on the side and the person may feel something on the face.

The more sensitive the body region, the larger the sensory cortex area devoted to it (Figure 2.20). Your supersensitive lips project to a larger brain area than do your toes, which is one reason we kiss with our lips rather than touch toes. Rats have a large area of the brain devoted to their whisker sensations, and owls to their hearing sensations.

Scientists have identified additional areas where the cortex receives input from senses other than touch. At this moment, you are receiving visual information in the visual cor- tex in your occipital lobes, at the back of your brain (FIGURES 2.21 and 2.22). Stimulated in the occipital lobes, you might see flashes of light or dashes of color. (In a sense, we do have eyes in the back of our head!) A friend of mine, having lost much of his right occipital lobe to a tumor removal, is now blind to the left half of his field of vision. Visual information travels from the occipital lobes to other areas that specialize in tasks such as identifying words, detecting emotions, and recognizing faces.

Toes

Ankle

Knee

HipTrunk

ArmWrist

Fingers

Thumb

Neck Brow

Eye

Face

Lips

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Toes

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Foot

Leg

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ArmHand

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Nose

Face

Lips

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Output: Motor cortex (Left hemisphere section controls the body’s right side)

Input: Sensory cortex (Left hemisphere section receives input from the body’s right side)

FIGURE 2.20

Left hemisphere tissue devoted

to each body part in the motor

cortex and the sensory cortex As you can see from this classic though inexact representation, the area devoted to a body part in the motor cortex (in the frontal lobes) or in the sensory cortex (in the parietal lobes) is not proportional to the body part’s size. Rather, the brain devotes more tissue to sensitive areas and to areas requiring precise control. Thus, the fingers have a greater representation in the cortex than does the upper arm.

FIGURE 2.21

The brain in action This fMRI (functional MRI) scan shows the visual cortex in the occipital lobes activated (color representation of increased bloodflow) as a research participant looks at a photo. When the person stops looking, the region instantly calms down.

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The visual cortex and

auditory cortex The visual cortex in the occipital lobes at the rear of your brain receives input from your eyes. The auditory cortex, in your temporal lobes—above your ears—receives information from your ears.

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56 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Motor areas

Rat Cat

Chimpanzee

Human Sensory areas

Association areas

Any sound you now hear is processed by your auditory cortex in your temporal lobes (just above your ears; see Figure 2.22). Most of this auditory information travels a circuitous route from one ear to the auditory receiving area above your opposite ear. If stimulated in your auditory cortex, you might hear a sound. MRI scans of people with schizophrenia have revealed active auditory areas in the temporal lobes during auditory hallucinations (Lennox et al., 1999). Even the phantom ringing sound experienced by people with hearing loss is—if heard in one ear—associated with activity in the tempo- ral lobe on the brain’s opposite side (Muhlnickel, 1998).

RETRIEVE IT

• Our brain’s

cortex registers and processes body touch and movement sensations. The cortex controls our voluntary movements.

ANSWERS: sensory; motor

Association Areas So far, we have pointed out small cortical areas that either receive sensory input or direct muscular output. Together, these occupy about one-fourth of the human brain’s thin, wrinkled cover. What, then, goes on in the remaining vast regions of the cortex? In these association areas (the peach-colored areas in FIGURE 2.23), neurons are busy with higher mental functions—many of the tasks that make us human.

Electrically probing an association area won’t trigger any observable response. So, unlike the sensory and motor areas, association area functions cannot be neatly mapped. Their silence has led to what Donald McBurney (1996, p. 44) called “one of the hardiest weeds in the garden of psychology”: the claim that we ordinarily use only 10 percent of our brain. (If true, wouldn’t this imply a 90 percent chance that a bullet to your brain would land in an unused area?) Surgically lesioned animals and brain-damaged humans bear witness that association areas are not dormant. Rather, these areas interpret, integrate, and act on sensory information and link it with stored memories—a very important part of thinking.

Association areas are found in all four lobes. In the frontal lobes, they enable judgment, planning, and processing of new memories. People with damaged frontal lobes may have intact memories, high scores on intelligence tests, and great cake-baking skills. Yet they would not be able to plan ahead to begin baking a cake for a birthday party (Huey et al., 2006).

Frontal lobe damage also can alter personality and remove a person’s inhibitions. Con- sider the classic case of railroad worker Phineas Gage. One afternoon in 1848, Gage, then 25 years old, was using a tamping iron to pack gunpowder into a rock. A spark ignited the gunpowder, shooting the rod up through his left cheek and out the top of his skull, leav- ing his frontal lobes massively damaged (FIGURE 2.24). To everyone’s amazement, he was immediately able to sit up and speak, and after the wound healed he returned to work. But the affable, soft-spoken man was now irritable, profane, and dishonest. This person, said his friends, was “no longer Gage.” His mental abilities and memories were intact, but his personality was not. (Although Gage lost his railroad job, he did, over time, adapt to his injury and find work as a stage coach driver [Macmillan & Lena, 2010].)

association areas areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.

FIGURE 2.23

Areas of the cortex in four

mammals More intelligent animals have increased “uncommitted” or association areas of the cortex. These vast areas of the brain are responsible for interpreting, integrating, and acting on sensory information and linking it with stored memories.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 57

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More recent studies of people with damaged frontal lobes have revealed similar impairments. Not only may they become less inhibited (without the frontal lobe brakes on their impulses), but their moral judgments seem unrestrained by normal emotions. Would you advocate pushing one person in front of a runaway boxcar to save five oth- ers? Most people do not, but those with damage to a brain area behind the eyes often do (Koenigs et al., 2007). With their frontal lobes ruptured, people’s moral compass seems to disconnect from their behavior.

Association areas also perform other mental functions. The parietal lobes, parts of which were large and unusually shaped in Einstein’s normal-weight brain, enable math- ematical and spatial reasoning (Witelson et al., 1999).

On the underside of the right temporal lobe, another association area enables us to recognize faces. If a stroke or head injury destroyed this area of your brain, you would still be able to describe facial features and to recognize someone’s gender and approximate age, yet be strangely unable to identify the person as, say, Lady Gaga, or even your grandmother.

Nevertheless, complex mental functions don’t reside in any one place. There is no one spot in a rat’s small association cortex that, when damaged, will obliterate its ability to learn or remember a maze. And as we’ll see in Chapter 9, distinct neural networks in the human brain coordinate to enable language. Memory, language, and attention result from the synchronized activity among distinct brain areas (Knight, 2007). Ditto for religious experience. More than 40 distinct brain regions become active in different religious states, such as prayer and meditation, indicating that there is no simple “God spot” (Fingelkurts & Fingelkurts, 2009). The point to remember: Our mental experiences arise from coordinated brain activity.

RETRIEVE IT

• Why are association areas important?

ANSWER: Association areas are involved in higher mental functions—interpreting, integrating, and acting on information processed in other areas.

The Brain’s Plasticity

2-11: To what extent can a damaged brain reorganize itself, and what is neurogenesis?

Our brains are sculpted not only by our genes but also by our experiences. In Chapter 4, we’ll focus more on how experience molds the brain. For now, let’s turn to another aspect of the brain’s plasticity: its ability to modify itself after damage.

plasticity the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.

FIGURE 2.24

A blast from the past (a) Phineas Gage’s skull was kept as a medical record. Using measurements and modern neuroimaging techniques, researchers have reconstructed the probable path of the rod through Gage’s brain (Damasio et al., 1994). (b) This recently discovered photo shows Gage after his accident. The image has been reversed to show the features correctly. (Early photos, such as this one, were actually mirror images.)

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58 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Some brain-damage effects described earlier can be traced to two hard facts: (1) Sev- ered brain and spinal cord neurons, unlike cut skin, usually do not regenerate. (If your spinal cord were severed, you would probably be permanently paralyzed.) And (2) some brain functions seem preassigned to specific areas. One newborn who suffered damage to temporal lobe facial recognition areas later remained unable to recognize faces (Farah et al., 2000). But there is good news: Some neural tissue can reorganize in response to damage. Under the surface of our awareness, the brain is constantly changing, building new pathways as it adjusts to little mishaps and new experiences.

Plasticity may also occur after serious damage, especially in young children (Kolb, 1989; see also FIGURE 2.25). The brain’s plasticity is good news for those blind or deaf. Blindness or deafness makes unused brain areas available for other uses (Amedi et al., 2005). If a blind person uses one finger to read Braille, the brain area dedicated to that finger expands as the sense of touch invades the visual cortex that normally helps people see (Barinaga, 1992a; Sadato et al., 1996). If magnetic stimulation temporarily “knocks out” the visual cortex, lifelong-blind people make more errors on a language task (Amedi et al., 2004). Plasticity also helps explain why some studies have found that deaf people have enhanced peripheral vision (Bosworth & Dobkins, 1999). In deaf people whose native language is sign, the temporal lobe area normally dedicated to hearing waits in vain for stimulation. Finally, it looks for other signals to process, such as those from the visual system.

Similar reassignment may occur when disease or damage frees up other brain areas normally dedicated to specific functions. If a slow-growing left hemisphere tumor disrupts language (which resides mostly in the left hemisphere), the right hemisphere may compensate (Thiel et al., 2006). If a finger is amputated, the sensory cortex that

received its input will begin to receive input from the adjacent fingers, which then become more sensitive (Fox, 1984). So what do you suppose was the sexual

intercourse experience of one patient whose lower leg had been amputated? “I actually experience my orgasm in my foot. [Note that in Figure 2.20, the toes region is adjacent to the genitals.] And there it’s much bigger than it used to be because it’s no longer just confined to my genitals” (Ramachandran & Blakeslee, 1998, p. 36).

Although the brain often attempts self-repair by reorganizing existing tis- sue, it sometimes attempts to mend itself by producing new brain cells. This

process, known as neurogenesis, has been found in adult mice, birds, monkeys, and humans (Jess- berger et al., 2008). These baby neurons originate deep in the brain and may then migrate elsewhere and form connections with neighboring neurons (Aimone et al., 2010; Gould, 2007).

Master stem cells that can develop into any type of brain cell have also been discovered in the human embryo. If mass-produced in a lab and injected into a damaged brain, might neural stem cells turn themselves into replacements for lost brain cells? Might surgeons someday be able to rebuild damaged brains, much as landscapers reseed damaged lawns? Might new drugs spur the production of new nerve cells? Stay tuned. Today’s biotech companies are hard at work on such pos- sibilities. In the meantime, we can all benefit from other natural promoters of neurogenesis, such as exercise, sleep, and nonstressful but stimulating environments (Iso et al., 2007; Pereira et al., 2007; Stranahan et al., 2006).Joe

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Brain plasticity This 6-year-old had surgery to end her life-threatening seizures. Although most of an entire hemisphere was removed (see MRI of hemispherectomy above), her remaining hemisphere compensated by putting other areas to work. One Johns Hopkins medical team reflected on the child hemispherectomies they had performed. Although use of the opposite arm was compromised, the team reported being “awed” by how well the children had retained their memory, personality, and humor (Vining et al., 1997). The younger the child, the greater the chance that the remaining hemisphere can take over the functions of the one that was surgically removed (Choi, 2008).

neurogenesis the formation of new neurons.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 59

Our Divided Brain

2-12: What do split brains reveal about the functions of our two brain hemispheres?

We have seen that our brain’s look-alike left and right hemispheres serve dif- fering functions. This lateralization is apparent after brain damage. Research spanning more than a century has shown that left hemisphere accidents, strokes, and tumors can impair reading, writing, speaking, arithmetic reasoning, and understanding. Similar right hemisphere lesions seldom have such dramatic effects.

Does this mean that the right hemisphere is just along for the ride—a silent, “sub- ordinate” or “minor” hemisphere? Many believed this was the case until 1960, when a fascinating chapter in psychology’s history began to unfold: Researchers found that the “minor” right hemisphere was not so limited after all.

Splitting the Brain In 1961, two Los Angeles neurosurgeons, Philip Vogel and Joseph Bogen, speculated that major epileptic seizures were caused by an amplification of abnormal brain activity bouncing back and forth between the two cerebral hemispheres. If so, they wondered, could they put an end to this biological tennis game by severing the corpus callosum, the wide band of axon fibers connecting the two hemispheres and carrying messages between them (FIGURE 2.26)? Vogel and Bogen knew that psychologists Roger Sperry, Ronald Myers, and Michael Gazzaniga had divided cats’ and monkeys’ brains in this manner, with no serious ill effects.

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So the surgeons operated. The result? The seizures all but disappeared. The patients with these split brains were surprisingly normal, their personality and intellect hardly affected. Waking from surgery, one even joked that he had a “split- ting headache” (Gazzaniga, 1967). By sharing their experiences, these patients have greatly expanded our understanding of interactions between the intact brain’s two hemispheres.

To appreciate these findings, we need to focus for a minute on the peculiar nature of our visual wiring, illustrated in FIGURE 2.27 on the next page. Note that each eye receives sensory information from both the right and left visual fields. In each eye, information from the left half of your field of vision goes to your right hemisphere, and information from the right half of your visual field goes to your left hemisphere, which usually controls speech. Data received by either hemisphere are quickly transmitted to the other across the corpus callosum. In a person with a severed corpus callosum, this information sharing does not take place.

corpus callosum [KOR-pus kah - LOW-sum] the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

split brain a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.

FIGURE 2.26

The corpus callosum This large band of neural fibers connects the two brain hemispheres. To photograph the half brain shown at left, a surgeon separated the hemispheres by cutting through the corpus callosum and lower brain regions. In the view on the right, brain tissue has been cut back to expose the corpus callosum and bundles of fibers coming out from it.

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60 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Knowing these facts, Sperry and Gazzaniga could send infor- mation to a patient’s left or right hemisphere. As the person stared at a spot, they flashed a stimulus to its right or left. They could do this with you, too, but in your intact brain, the hemi- sphere receiving the information would instantly pass the news to

the other side. Because the split-brain surgery had cut the communication lines between the hemispheres, the researchers could, with these patients, quiz each hemisphere separately.

In an early experiment, Gazzaniga (1967) asked these people to stare at a dot as he flashed HE·ART on a screen (FIGURE 2.28). Thus, HE appeared in their left visual field (which transmits to the right hemisphere) and ART in the right field (which transmits to the left hemisphere). When he then asked them to say what they had seen, the patients reported that they had seen ART. But when asked to point to the word they had seen, they were startled when their left hand (controlled by the right hemisphere) pointed to HE. Given an opportunity to express itself, each hemisphere indicated what it had seen. The right hemisphere (controlling the left hand) intuitively knew what it could not verbally report.

When a picture of a spoon was flashed to their right hemisphere, the patients could not say what they had viewed. But when asked to identify what they had viewed by feeling an assortment of hidden objects with their left hand, they readily selected the spoon. If the experimenter said, “Correct!” the patient might reply, “What? Correct? How could I possibly pick out the correct object when I don’t know what I saw?” It is, of course, the left hemisphere doing the talking here, bewildered by what the nonverbal right hemisphere knows.

A few people who have had split-brain surgery have been for a time bothered by the unruly independence of their left hand, which might unbutton a shirt while the right hand buttoned it, or put grocery store items back on the shelf after the right hand put

Visual area of left hemisphere

Left visual field

Right visual field

Optic nerves

Speech

Visual area of right hemisphere

Corpus callosum

Optic chiasm

“Point with your left hand to the word you saw.”

or

“Look at the dot.”

“What word did you see?”

Two words separated by a dot are momentarily projected.

(b)

(c)

(a)

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The information highway

from eye to brain

FIGURE 2.28

Testing the divided brain When an experimenter flashes the word HEART across the visual field, a woman with a split brain verbally reports seeing the portion of the word transmitted to her left hemisphere. However, if asked to indicate with her left hand what she saw, she points to the portion of the word transmitted to her right hemisphere. (From Gazzaniga, 1983.)

“Do not let your left hand know what your right hand is doing.”

Matthew 6:3

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 61

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Pop psychology’s idea of hemispheric specialization Alas, reality is more complex.

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them in the cart. It was as if each hemisphere was thinking “I’ve half a mind to wear my green (blue) shirt today.” Indeed, said Sperry (1964), split-brain surgery leaves people “with two separate minds.” With a split brain, both hemispheres can comprehend and follow an instruction to copy—simultaneously—different figures with the left and right hands (Franz et al., 2000; see also FIGURE 2.29). (Reading these reports, I fantasize a patient enjoying a solitary game of “rock, paper, scissors”—left versus right hand.)

When the “two minds” are at odds, the left hemisphere does mental gymnastics to rationalize reactions it does not understand. If a patient follows an order (“Walk”) sent to the right hemisphere, a strange thing happens. The left hemisphere, unaware of the order, doesn’t know why the patient begins walking. If asked why, the patient doesn’t reply, “I don’t know.” Instead, the left hemisphere improvises—“I’m going into the house to get a Coke.” Gazzaniga (1988), who considers these patients “the most fascinating people on earth,” concluded that the conscious left hemisphere is an “interpreter” or press agent that instantly constructs theories to explain our behavior.

RETRIEVE IT

• (1) If we flash a red light to the right hemisphere of a person with a split brain, and flash a green light to the left hemisphere, will each observe its own color? (2) Will the person be aware that the colors differ? (3) What will the person verbally report seeing?

ANSWERS: 1. yes, 2. no, 3. green

Right-Left Differences in the Intact Brain So, what about the 99.99+ percent of us with undivided brains? Does each of our hemi- spheres also perform distinct functions? Several different types of studies indicate they do. When a person performs a perceptual task, for example, brain waves, bloodflow, and glucose consumption reveal increased activity in the right hemisphere. When the person speaks or calculates, activity increases in the left hemisphere.

A dramatic demonstration of hemispheric specialization happens before some types of brain surgery. To locate the patient’s language centers, the surgeon injects a sedative into the neck artery feeding blood to the left hemisphere, which usually controls speech. Before the injection, the patient is lying down, arms in the air, chatting with the doc- tor. Can you predict what probably happens when the drug puts the left hemisphere to sleep? Within seconds, the person’s right arm falls limp. If the left hemisphere is controlling language, the patient will be speechless until the drug wears off. If the drug is injected into the artery to the right hemisphere, the left arm will fall limp, but the person will still be able to speak.

To the brain, language is language, whether spoken or signed. Just as hearing people usually use the left hemisphere to process spoken language, deaf people use the left hemisphere to process sign language (Corina et al., 1992; Hickok et al., 2001). Thus, a left hemisphere stroke disrupts a deaf person’s signing, much as it would disrupt a hearing person’s speaking. The same brain area is involved in both (Corina, 1998). (For more on how the brain enables language, see Chapter 9.)

Although the left hemisphere is adept at making quick, literal interpretations of language, the right hemisphere helps us modulate our speech to make meaning clear—as when we ask “What’s that in the road ahead?” instead of “What’s that in the road, a head?” (Heller, 1990). The right hemisphere also helps orchestrate our self-awareness. People who suffer partial paralysis will sometimes obstinately deny their impair- ment—strangely claiming they can move a paralyzed limb—if the damage is to the right hemisphere (Berti et al., 2005).

Simply looking at the two hemispheres, so alike to the naked eye, who would suppose they contribute uniquely to the harmony of the whole? Yet a variety of observations—of people with split brains, of people with normal brains, and even of other species’ brains—converge beautifully, leaving little doubt that we have unified brains with specialized parts (Hopkins & Cantalupo 2008; MacNeilage et al., 2009).

FIGURE 2.29

Try this! Joe, who has had split-brain surgery, can simultaneously draw two different shapes.

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62 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

How does the brain’s intricate networking emerge? How does our heredity—the legacy of our ancestral history—conspire with our experiences to organize and “wire” the brain? To that we turn next.

Behavior Genetics: Predicting Individual Differences

2-13: What are genes, and how do behavior geneticists explain our individual differences?

Our shared brain architecture predisposes some common behavioral ten- dencies. Whether we live in the Arctic or the tropics, we sense the world, develop language, and feel hunger through identical mechanisms. We prefer sweet tastes to sour. We divide the color spectrum into similar colors. And we feel drawn to behav- iors that produce and protect offspring.

Our human family shares not only a common biological heritage—cut us and we bleed—but also common social behaviors. Whether named Wong, Nkomo, Smith, or Gonzales, we start fearing strangers at about eight months, and as adults we prefer the company of those with attitudes and attributes similar to our own. As members of one spe- cies, we affiliate, conform, return favors, punish offenses, organize hierarchies of status, and grieve a child’s death. A visitor from outer space could drop in anywhere and find humans dancing and feasting, singing and worshiping, playing sports and games, laughing and cry- ing, living in families and forming groups. We are the leaves of one tree.

But in important ways, we also are each unique. We look different. We sound differ- ent. We have varying personalities, interests, and cultural and family backgrounds. What causes our striking diversity? How much of it is shaped by our differing genes, and how much by our environment—by every external influence, from maternal nutrition while in the womb to social support while nearing the tomb? How does our heredity interact with our experiences to create both our universal human nature and our indi- vidual and social diversity? Such questions intrigue behavior geneticists.

Genes: Our Codes for Life Barely more than a century ago, few would have guessed that every cell nucleus in your body contains the genetic master code for your entire body. It’s as if every room in Dubai’s Burj Khalifa (the world’s tallest building) contained a book detailing the archi- tect’s plans for the entire structure. The plans for your own book of life run to 46 chap- ters—23 donated by your mother’s egg and 23 by your father’s sperm. Each of these 46 chapters, called a chromosome, is composed of a coiled chain of the molecule DNA (deoxyribonucleic acid). Genes, small segments of the giant DNA molecules, form the words of those chapters (FIGURE 2.30). All told, you have 20,000 to 25,000 gene words, which can be either active (expressed) or inactive. Environmental events “turn on” genes, rather like hot water enabling a tea bag to express its flavor. When turned on, genes pro- vide the code for creating protein molecules, our body’s building blocks.

Geneticists and psychologists are interested in the occasional variations found at par- ticular gene sites in human DNA. Slight person-to -person variations from the common pattern give clues to our uniqueness—why one person has a disease that another does not, why one person is short and another tall, why one is outgoing and another shy.

Most of our traits are influenced by many genes. How tall you are, for example, reflects the size of your face, vertebrae, leg bones, and so forth—each of which may be influenced by different genes interacting with your specific environment. Complex traits such as intelligence, happiness, and aggressiveness are similarly influenced by groups of genes. Thus our genetic predispositions—our genetically influenced traits—help explain both our shared human nature and our human diversity.

The nurture of nature Parents every- where wonder: Will my baby grow up to be peaceful or aggressive? Homely or attractive? Successful or struggling at every step? What comes built in, and what is nurtured—and how? Research reveals that nature and nurture together shape our development—every step of the way.

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“Your DNA and mine are 99.9 percent the same. . . . At the DNA level, we are clearly all part of one big worldwide family.”

Francis Collins, Human Genome Project director, 2007

“We share half our genes with the banana.”

Evolutionary biologist Robert May, president of Britain’s Royal Society, 2001

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 63

Cell

Chromosome

Nucleus

DNA

Gene

FIGURE 2.30

The life code The nucleus of every human cell contains chromosomes, each of which is made up of two strands of DNA connected in a double helix.

environment every nongenetic influence, from prenatal nutrition to the people and things around us.

behavior genetics the study of the rela- tive power and limits of genetic and environ- mental influences on behavior.

chromosomes threadlike structures made of DNA molecules that contain the genes.

DNA (deoxyribonucleic acid) a com- plex molecule containing the genetic informa- tion that makes up the chromosomes.

genes the biochemical units of heredity that make up the chromosomes; segments of DNA capable of synthesizing proteins.

identical twins twins who develop from a single (monozygotic) fertilized egg that splits in two, creating two genetically identical organisms.

fraternal twins twins who develop from separate (dizygotic) fertilized eggs. They are genetically no closer than ordinary brothers and sisters, but they share a fetal environment.

RETRIEVE IT

• Put the following cell structures in order from smallest to largest: nucleus, gene, chromosome.

ANSWER: gene, chromosome, nucleus

• When the mother’s egg and the father’s sperm unite, each contributes 23

.

ANSWER: chromosomes

Twin and Adoption Studies To scientifically tease apart the influences of environment and heredity, behavior geneti- cists would need to design two types of experiments. The first would control the home environment while varying heredity. The second would control heredity while varying the home environment. Such experiments with human infants would be unethical, but happily for our purposes, nature has done this work for us.

Identical Versus Fraternal Twins Identical twins develop from a single (monozygotic) fertilized egg that splits in two. Thus they are genetically identical—nature’s own human clones (FIGURE 2.31 on the next page). Indeed, they are clones who share not only the same genes but the same conception and uterus, and usually the same birth date and cultural history.

Fraternal twins develop from separate (dizygotic) fertilized eggs. As womb-mates, they share a fetal environment, but they are genetically no more similar than ordinary brothers and sisters.

Shared genes can translate into shared experiences. A person whose identical twin has Alzheimer’s disease, for example, has a 60 percent risk of getting the disease; if the affected twin is fraternal, the risk is 30 percent (Plomin et al., 1997). To study the effects of genes and “Thanks for almost everything, Dad.”

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64 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Fraternal twins

Identical twins

Same sex only

Same or opposite sex

FIGURE 2.31

Same fertilized egg,

same genes; different

eggs, different

genes Identical twins develop from a single fertilized egg, fraternal twins from two.

environments, hundreds of researchers have studied some 800,000 identical and frater- nal twin pairs (Johnson et al., 2009).

Are identical twins, being genetic clones of each other, also behaviorally more similar than fraternal twins? Studies of thousands of twin pairs in Sweden, Finland, and Australia have found that on the personality traits of extraversion (outgoingness) and neuroti- cism (emotional instability), identical twins are much more similar than fraternal twins.

Identical twins, more than fraternal twins, also report being treated alike. So, do their experiences rather than their genes account for their similarity? No. Studies have shown that identical twins whose parents treated them alike were not psychologically more alike than identical twins who were treated less similarly (Loehlin & Nichols, 1976). In explaining individual differences, genes matter.

Twins Curiously, twinning rates vary by race. The rate among Caucasians is roughly twice that of Asians and half that of Africans. In Africa and Asia, most twins are identical. In Western countries, most twins are fraternal, and fraternal twins have increased with the use of fertility drugs (Hall, 2003; Steinhauer, 1999).

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Sweden has the world’s largest national twin registry—140,000 living and dead twin pairs—which forms part of a massive registry of 600,000 twins currently being sampled in the world’s largest twin study (Wheelwright, 2004; www.genomeutwin.org).

Separated Twins Imagine the following science fiction experiment: A mad scientist decides to separate identical twins at birth, then rear them in differing environments. Better yet, consider a true story:

On a chilly February morning in 1979, some time after divorcing his first wife, Linda, Jim Lewis awoke in his modest home next to his second wife, Betty. Determined that this marriage would work, Jim made a habit of leaving love notes to Betty around the house. As he lay in bed he thought about others he had loved, including his son, James Alan, and his faithful dog, Toy.

Jim was looking forward to spending part of the day in his basement woodworking shop, where he had put in many happy hours building furniture, picture frames, and other items, including a white bench now circling a tree in his front yard. Jim also liked to spend free time driving his Chevy, watching stock-car racing, and drinking Miller Lite beer.

Jim was basically healthy, except for occasional half-day migraine headaches and blood pressure that was a little high, perhaps related to his chain-smoking habit. He had become overweight a while back but had shed some of the pounds. Having undergone a vasectomy, he was done having children.

What was extraordinary about Jim Lewis, however, was that at that same moment (I am not making this up) there existed another man—also named Jim—for whom

Twins Lorraine and Levinia Christmas, driving to deliver Christmas presents to each other near Flitcham, England, collided (Shepherd, 1997).

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 65

all these things (right down to the dog’s name) were also true.2 This other Jim—Jim Springer—just happened, 38 years earlier, to have been his fetal partner. Thirty-seven days after their birth, these genetically identical twins were separated, adopted by blue-collar families, and reared with no contact or knowledge of each other’s whereabouts until the day Jim Lewis received a call from his genetic clone (who, having been told he had a twin, set out to find him).

One month later, the brothers became the first twin pair tested by Univer- sity of Minnesota psychologist Thomas Bouchard and his colleagues, begin- ning a study of separated twins that extends to the present (Holden, 1980a,b; Wright, 1998). Their voice intonations and inflections were so similar that, hearing a playback of an earlier interview, Jim Springer guessed “That’s me.” Wrong—it was his brother. Given tests measuring their personality, intel- ligence, heart rate, and brain waves, the Jim twins—despite 38 years of separation—were virtually as alike as the same person tested twice. Both married women named Dorothy Jane Scheckelburger. Okay, the last item is a joke. But as Judith Rich Harris (2006) has noted, it would hardly be weirder than some other reported similarities.

Aided by publicity in magazine and newspaper stories, Bouchard (2009) and his colleagues located and studied 74 pairs of identical twins reared apart. They continued to find similarities not only of tastes and physical attributes but also of personality (characteristic patterns of thinking, feeling, and acting), abilities, attitudes, interests, and even fears.

In Sweden, Nancy Pedersen and her co-workers (1988) identified 99 separated identical twin pairs and more than 200 separated fraternal twin pairs. Compared with equivalent samples of identical twins reared together, the separated identical twins had somewhat less identical personalities. Still, separated twins were more alike if genetically identical than if fraternal. And separation shortly after birth (rather than, say, at age 8) did not amplify their personality differences.

Stories of startling twin similarities have not impressed Bouchard’s critics. “The plural of anecdote is not data,” they have pointed out, noting that if any two strangers were to spend hours comparing their behaviors and life histories, they would probably discover many coincidental similarities. If researchers created a control group of biologically unrelated pairs of the same age, sex, and ethnicity, who had not grown up together but who were as similar to one another in economic and cultural background as are many of the separated twin pairs, wouldn’t these pairs also exhibit striking similarities (Joseph, 2001)? Bouchard has replied that separated fraternal twins do not exhibit similarities comparable to those of separated identical twins.

Even the impressive data from personality assessments are clouded by the reunion of many of the separated twins some years before they were tested. Moreover, identical twins share an appearance, and the responses it evokes. Adoption agencies also tend to place separated twins in similar homes. Despite these criticisms, the striking twin-study results helped shift scientific thinking toward a greater appreciation of genetic influences.

If genetic influences help explain individual differences, do they also help explain group differences between men and women, or between people of different races? Not necessarily. Individual differences in height and weight, for example, are highly heritable; yet nutrition (an environmental factor) rather than genetic influences explains why, as a group, today’s adults are taller and heavier than those of a century ago. The two groups differ, but not because human genes have changed in a mere century’s eyeblink of time. Ditto aggressiveness, a genetically influenced trait. Today’s peaceful Scandinavians differ from their more aggressive Viking ancestors, despite car- rying many of the same genes.

2 Actually, this description of the two Jims errs in one respect: Jim Lewis named his son James Alan. Jim Springer named his James Allan.

Identical twins are people two Identical twins Jim Lewis and Jim Springer were separated shortly after birth and raised in different homes without awareness of each other. Research has shown remarkable similari- ties in the life choices of separated identical twins, lending support to the idea that genes influence personality.

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Bouchard’s famous twin research was, appropriately enough, conducted in Minneapolis, the “Twin City” (with St. Paul) and home to the Minnesota Twins baseball team.

Coincidences are not unique to twins. Patricia Kern of Colorado was born March 13, 1941, and named Patricia Ann Campbell. Patricia DiBiasi of Oregon also was born March 13, 1941, and named Patricia Ann Campbell. Both had fathers named Robert, worked as bookkeepers, and at the time of this comparison had children ages 21 and 19. Both studied cosmetology, enjoyed oil painting as a hobby, and married military men, within 11 days of each other. They are not genetically related. (From an AP report, May 2, 1983.)

“In some domains it looks as though our identical twins reared apart are . . . just as similar as identical twins reared together. Now that’s an amazing finding and I can assure you none of us would have expected that degree of similarity.”

Thomas Bouchard (1981)

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66 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Biological Versus Adoptive Relatives For behavior geneticists, nature’s second real-life experiment—adoption—creates two groups: genetic relatives (biological parents and siblings) and environmental relatives (adop- tive parents and siblings). For personality or any other given trait, we can therefore ask whether adopted children are more like their biological parents, who contributed their genes, or their adoptive parents, who contribute a home environment. While sharing that home environment, do adopted siblings also come to share traits?

The stunning finding from studies of hundreds of adoptive families is that people who grow up together, whether biologically related or not, do not much resemble one another in personality (McGue & Bouchard, 1998; Plomin, 2011; Rowe, 1990). In per- sonality traits such as extraversion and agreeableness, adoptees are more similar to their biological parents than to their caregiving adoptive parents.

The finding is important enough to bear repeating: The environment shared by a fam- ily’s children has virtually no discernible impact on their personalities. Two adopted children reared in the same home are no more likely to share personality traits with each other than with the child down the block. Heredity shapes other primates’ personalities, too. Macaque monkeys raised by foster mothers exhibit social behaviors that resemble their biological, rather than foster, mothers (Maestripieri, 2003). Add all this to the similarity of identical twins, whether they grow up together or apart, and the effect of a shared rearing environment seems shockingly modest.

The genetic leash may limit the family environment’s influence on personality, but this does not mean that adoptive parenting is a fruitless venture. Parents do influence their chil- dren’s attitudes, values, manners, faith, and politics (Reifman & Cleveland, 2007). A pair of adopted children or identical twins will, especially during adolescence, have more similar religious beliefs if reared together (Koenig et al., 2005). Parenting matters!

Moreover, in adoptive homes, child neglect and abuse and even parental divorce are rare. (Adoptive parents are carefully screened; natural parents are not.) So it is not surprising that, despite a somewhat greater risk of psychological disorder, most adopted children thrive, especially when adopted as infants (Loehlin et al., 2007; van IJzendoorn & Juffer, 2006; Wierzbicki, 1993). Seven in eight report feeling strongly attached to one or both adoptive parents. As children of self-giving parents, they grow up to be more self-giving and altruistic than average (Sharma et al., 1998). Many score higher than their biological parents on intelligence tests, and most grow into happier and more stable adults. In one Swedish study, children adopted as infants grew up with fewer problems than were experienced by children whose biological mothers initially registered them for adoption but then decided to raise the children themselves (Bohman & Sigvardsson, 1990). Regardless of personality differences between adoptive family members, children benefit from adoption.

Nature or nurture or both? When talent runs in families, as with Wynton Marsalis, Branford Marsalis, and Delfeayo Marsalis, how do heredity and environment together do their work? AP

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“We carry to our graves the essence of the zygote that was first us.”

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The greater uniformity of adoptive homes—mostly healthy, nurturing homes—helps explain the lack of striking differences when comparing child outcomes of different adoptive homes (Stoolmiller, 1999).

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 67

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RETRIEVE IT

• How do researchers use twin and adoption studies to learn about psychological principles?

ANSWER: Researchers compare the traits and behaviors of identical twins (same genes) and fraternal twins (different genes, as in any two siblings). They also compare adopted children with their adoptive and biological parents. Some studies compare twins raised together or separately. These studies help us determine how much variation among individuals is due to genetic makeup and how much to environmental factors.

Gene-Environment Interaction

2-14: How do heredity and environment work together?

Among our similarities, the most important—the behavioral hallmark of our species—is our enormous adaptive capacity. Some human traits, such

as having two eyes, develop the same in virtually every environment. But other traits are expressed only in particular environments. Go barefoot for a summer and you will develop toughened, callused feet—a biological adaptation to friction. Mean- while, your shod neighbor will remain a tenderfoot. The difference between the two of you is, of course, an effect of environment. But it is also the product of a biologi- cal mechanism—adaptation.

Genes and environment—nature and nurture—work together, like two hands clapping. Genes are self-regulating. Rather than acting as blueprints that lead to the same result no matter the context, genes react. An African butterfly that is green in summer turns brown in fall, thanks to a temperature-controlled genetic switch. The genes that produce brown in one situation produce green in another.

To say that genes and experience are both important is true. But more precisely, they interact. Imagine two babies, one genetically predisposed to be attractive, sociable, and easygoing, the other less so. Assume further that the first baby attracts more affectionate and stimulating care and so develops into a warmer and more outgoing person. As the two children grow older, the more naturally outgoing child more often seeks activities and friends that encourage further social confidence.

What has caused their resulting personality differences? Neither hered- ity nor experience acts alone. Environments trigger gene activity. And our genetically influenced traits evoke significant responses in others. Thus, a child’s impulsivity and aggression may evoke an angry response from a parent or teacher who reacts warmly to model children in the family or classroom. In such cases, the child’s nature and the adult’s nurture interact. Gene and scene dance together.

Evocative interactions may help explain why identical twins reared in different families recall their parents’ warmth as remarkably similar— almost as similar as if they had had the same parents (Plomin et al., 1988, 1991, 1994). Fraternal twins have more differing recollections of their early family life—even if reared in the same family! “Children experience us as different parents, depending on their own qualities,” noted Sandra Scarr (1990).

Recall that genes can be either active (expressed, as the hot water activates the tea bag) or inactive. A new field, epigenetics (meaning “in addition to” or “above and beyond” genetics), is studying the molecular mechanisms by which environments trigger genetic expression. Although genes have the potential to influence development, environmental trig- gers can switch them on or off, much as your computer’s software switches your printer on and off. One such epigenetic mark is an organic methyl molecule attached to part of a DNA strand (FIGURE 2.32). It instructs the cell to ignore any gene present in that DNA stretch, thereby preventing the DNA from producing the proteins coded by that gene.

Genes

Gene expression blocked by epigenetic molecules

Prenatal

Postnatal

Juvenile

drugs, toxins, nutrition, stress

neglect, abuse, variations in care

social contact, environmental complexity

“Men’s natures are alike; it is their habits that carry them far apart.”

Confucius, Analects, 500 B.C.E.

“Heredity deals the cards; environment plays the hand.”

Psychologist Charles L. Brewer (1990)

interaction the interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).

epigenetics the study of environmental influences on gene expression that occur with- out a DNA change.

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FIGURE 2.32

Epigenetics influences

gene expression Life experiences beginning in the womb lay down epigenetic marks—often organic methyl molecules—that can block the expression of any gene in that DNA segment. (From Frances Champagne, 2010.)

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68 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Gene-environment interaction Biological appearances have social conse- quences. People respond differently to a Channing Tatum (shown here in the movie Dear John), than to his fellow actor Mike Myers (shown here playing the character Austin Powers).

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Environmental factors such as diet, drugs, toxins, and stress can affect the epigen- etic molecules that regulate gene expression. In one experiment, infant rats deprived of their mothers’ normal licking had more molecules that blocked access to the “on” switch for developing the brain’s stress-hormone receptors. When stressed, the animals had above-average levels of free-floating stress hormones and were more stressed out (Champagne et al., 2003; Champagne & Mashoodh, 2009). Child abuse may similarly affect its victims. Suicide victims with a history of child abuse exhibit the epigenetic effect (McGowan et al., 2009). Researchers now wonder if epigenetics might help solve some scientific mysteries, such as why only one member of an identical twin pair may develop a genetically influenced mental disorder, and how experience leaves its finger- prints in our brains.

So, if Jaden Agassi, son of tennis stars Andre Agassi and Stefanie Graf, grows up to be a tennis star, should we attribute his superior talent to his Grand Slam genes? To his growing up in a tennis-rich environment? To high expectations? The best answer seems to be “All of the above.” From conception onward, we are the product of a cascade of interactions between our genetic predispositions and our surrounding environments (McGue, 2010). Our genes affect how people react to and influence us. Forget nature versus nurture; think nature via nurture.

RETRIEVE IT

• Match the following terms to the correct explanation.

1. Epigenetics a. Study of the relative effects of our genes and our environment on our behavior.

2. Behavior genetics b. Study of environmental factors that affect how our genes are expressed.

ANSWERS: 1. b, 2. a

Evolutionary Psychology: Understanding Human Nature

2-15: How do evolutionary psychologists use natural selection to explain behavior tendencies?

Behavior geneticists explore the genetic and environmental roots of human differences. Evolutionary psychologists instead focus mostly on what makes us so much alike as humans. They use Charles Darwin’s principle of natural selection to

evolutionary psychology the study of the evolution of behavior and the mind, using principles of natural selection.

natural selection the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 69

mutation a random error in gene replication that leads to a change.

understand the roots of behavior and mental processes. Richard Dawkins (2007) calls natural selection “arguably the most momentous idea ever to occur to a human mind.” The idea, simplified, is this:

• Organisms’ varied offspring compete for survival. • Certain biological and behavioral variations increase organisms’ reproductive and

survival chances in their particular environment.

• Offspring that survive are more likely to pass their genes to ensuing generations. • Thus, over time, population characteristics may change.

To see these principles at work, let’s consider a straightforward example in foxes.

Natural Selection and Adaptation A fox is a wild and wary animal. If you capture a fox and try to befriend it, be careful. Stick your hand in the cage and, if the timid fox cannot flee, it may snack on your fingers. Russian scientist Dmitry Belyaev wondered how our human ancestors had domesticated dogs from their equally wild wolf forebears. Might he, within a comparatively short stretch of time, accomplish a similar feat by trans- forming the fearful fox into a friendly fox?

To find out, Belyaev set to work with 30 male and 100 female foxes. From their offspring he selected and mated the tamest 5 percent of males and 20 percent of females. (He measured tameness by the foxes’ responses to attempts to feed, handle, and stroke them.) Over more than 30 generations of foxes, Belyaev and his successor, Lyudmila Trut, repeated that simple procedure. Forty years and 45,000 foxes later, they had a new breed of foxes that, in Trut’s (1999) words, are “docile, eager to please, and unmistakably domesticated. . . . Before our eyes, ‘the Beast’ has turned into ‘beauty,’ as the aggressive behavior of our herd’s wild [ancestors] entirely disappeared.” So friendly and eager for human contact are they, so inclined to whimper to attract attention and to lick people like affectionate dogs, that the cash-strapped institute seized on a way to raise funds—marketing its foxes to people as house pets.

Over time, traits that confer a reproductive advantage on an individual or a species are selected and will prevail. Animal breeding experiments exploit genetic selection. Dog breeders have given us sheepdogs that herd, retrievers that retrieve, trackers that track, and pointers that point (Plomin et al., 1997). Psychologists, too, have bred animals to be serene or reactive, quick learners or slow ones.

Does the same process work with naturally occurring selection? Does natural selec- tion explain our human tendencies? Nature has indeed selected advantageous variations from the new gene combinations produced at each human conception and the muta- tions (random errors in gene replication) that sometimes result. But the tight genetic leash that predisposes a dog’s retrieving, a cat’s pouncing, or an ant’s nest building is looser on humans. The genes selected during our ancestral history endow us with a great capacity to learn and therefore to adapt to life in varied environments, from the tundra to the jungle. Genes and experience together wire the brain. Our adaptive flexibility in responding to different environments contributes to our fitness—our ability to survive and reproduce.

RETRIEVE IT

• How are Belyaev and Trut’s breeding practices similar to, and how do they differ from, the way natural selection normally occurs?

ANSWER: Over multiple generations, Belyaev and Trut have been selecting and breeding foxes that exhibited a trait they desired: tameness. This process is similar to naturally occurring selection, but it differs in that natural selection normally favors traits (including those arising from mutations) that contribute to reproduction and survival.

Eric Isselée/Shutterstock

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70 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

Evolutionary Success Helps Explain Similarities Our behavioral and biological similarities arise from our shared human genome, our common genetic profile. How did we develop our genetic kinship?

Our Genetic Legacy At the dawn of human history, our ancestors faced certain questions: Who is my ally, who is my foe? With whom should I mate? What food should I eat? Some individu- als answered those questions more successfully than others. For example, women who experienced nausea in the critical first three months of pregnancy were predisposed to avoid certain bitter, strongly flavored, and novel foods. Avoiding such foods has survival value, since they are the very foods most often toxic to prenatal development (Schmitt & Pilcher, 2004). Early humans disposed to eat nourishing rather than poisonous foods survived to contribute their genes to later generations. Those who deemed leopards “nice to pet” often did not.

Similarly successful were those whose mating helped them produce and nurture off- spring. Over generations, the genes of individuals not so disposed tended to be lost from the human gene pool. As success-enhancing genes continued to be selected, behavioral tendencies and thinking and learning capacities emerged that prepared our Stone Age ancestors to survive, reproduce, and send their genes into the future, and into you.

As inheritors of this prehistoric genetic legacy, we are predisposed to behave in ways that promoted our ancestors’ surviving and reproducing. But in some ways, we are biologically prepared for a world that no longer exists. We love the taste of sweets and fats, which prepared our ancestors to survive famines, and we heed their call from store shelves, fast-food outlets, and vending machines. With famine now rare in Western cultures, obesity is truly a growing problem. Our natural dispositions, rooted deep in his- tory, are mismatched with today’s junk-food environment and tomorrow’s threats, such as climate change (Colarelli & Dettman, 2003).

Evolutionary Psychology Today Darwin’s theory of evolution has been an organizing principle for biology for a long time. As Jared Diamond (2001) has noted, “Virtually no contemporary scientists believe that Darwin was basically wrong.” Today, Darwin’s theory lives on in the second Darwin- ian revolution: the application of evolutionary principles to psychology. In concluding On the Origin of Species, Darwin (1859, p. 346) anticipated this, foreseeing “open fields for far more important researches. Psychology will be based on a new foundation.”

In chapters to come, we’ll address some questions that intrigue evolutionary psychol- ogists: Why do infants start to fear strangers about the time they become mobile? Why are biological fathers so much less likely than unrelated boyfriends to abuse and murder the children with whom they share a home? Why do so many more people have phobias about spiders, snakes, and heights than about more dangerous threats, such as guns and electricity? And why do we fear air travel so much more than driving?

* * * I know from my mail and from public opinion surveys that some readers feel troubled

by the naturalism and evolutionism of contemporary science. Readers from other nations bear with me, but in the United States there is a wide gulf between

scientific and lay thinking about evolution. “The idea that human minds are the product of evolution is . . . unassailable fact,” declared a 2007 editorial in Nature, a leading science magazine. That sentiment concurs with a 2006 statement of “evidence-based facts” about evolution jointly issued by the national science academies of 66 nations (IAP, 2006). In The Lan- guage of God, Human Genome Project director Francis Collins (2006,

pp. 141, 146), a self-described evangelical Christian, compiles the “utterly Jacob Hamblin/Shutterstock

Despite high infant mortality and rampant disease in past millennia, not one of your countless ancestors died childless.

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 71

compelling” evidence that leads him to conclude that Darwin’s big idea is “unquestion- ably correct.” Yet Gallup reports that half of U.S. adults do not believe in evolution’s role in “how human beings came to exist on Earth” (Newport, 2007). Many of those who dispute the scientific story worry that a science of behavior (and evolutionary science in particular) will destroy our sense of the beauty, mystery, and spiritual significance of the human creature. For those concerned, I offer some reassuring thoughts.

When Isaac Newton explained the rainbow in terms of light of differing wavelengths, the poet Keats feared that Newton had destroyed the rainbow’s mysterious beauty. Yet, as Richard Dawkins (1998) noted in Unweaving the Rainbow, Newton’s analysis led to an even deeper mystery—Einstein’s theory of special relativity. Moreover, nothing about Newton’s optics need diminish our appreciation for the dramatic elegance of a rainbow arching across a brightening sky.

When Galileo assembled evidence that the Earth revolved around the Sun, not vice versa, he did not offer irrefutable proof for his theory. Rather, he offered a coherent explanation for a variety of observations, such as the changing shadows cast by the Moon’s mountains. His explanation eventually won the day because it described and explained things in a way that made sense, that hung together. Darwin’s theory of evolu- tion likewise is a coherent view of natural history. It offers an organizing principle that unifies various observations.

Collins is not the only person of faith to find the scientific idea of human origins congenial with his spirituality. In the fifth century, St. Augustine (quoted by Wilford, 1999) wrote, “The universe was brought into being in a less than fully formed state, but was gifted with the capacity to transform itself from unformed matter into a truly marvelous array of structures and life forms.” Some 1600 years later, Pope John Paul II in 1996 welcomed a science-religion dialogue, finding it noteworthy that evolutionary theory “has been progressively accepted by researchers, following a series of discoveries in various fields of knowledge.”

Meanwhile, many people of science are awestruck at the emerging understanding of the universe and the human creature. It boggles the mind—the entire universe popping out of a point some 14 billion years ago, and instantly inflating to cosmologi- cal size. Had the energy of this Big Bang been the tiniest bit less, the universe would have collapsed back on itself. Had it been the tiniest bit more, the result would have been a soup too thin to support life. Astronomer Sir Martin Rees has described Just Six Numbers (1999), any one of which, if changed ever so slightly, would produce a cosmos in which life could not exist. Had gravity been a tad stronger or weaker, or had the weight of a carbon proton been a wee bit different, our universe just wouldn’t have worked.

What caused this almost-too-good-to- be-true, finely tuned universe? Why is there something rather than nothing? How did it come to be, in the words of Harvard- Smithsonian astrophysicist Owen Gingerich (1999), “so extraordinarily right, that it seemed the universe had been expressly designed to produce intelligent, sentient beings”? Is there a benevolent superintelligence behind it all? Have there instead been an infinite number of universes born and we just happen to be the lucky inhabitants of one that, by chance, was exquisitely fine-tuned to give birth to us? Or does that idea violate Occam’s razor, the principle that we should prefer the simplest of compet- ing explanations? On such matters, a humble, awed, scientific silence is appropriate, suggested philosopher Ludwig Wittgenstein: “Whereof one cannot speak, thereof one must be silent.”

Rather than fearing science, we can welcome its enlarging our understanding and awakening our sense of awe. In The Fragile Species, Lewis Thomas (1992) described his utter amazement that the Earth in time gave rise to bacteria and eventually to Bach’s Mass in B Minor. In a short 4 billion years, life on Earth has come from nothing to structures as complex as a 6-billion-unit strand of DNA and the incomprehensible intricacy of the human brain. Atoms no different from those in a rock somehow formed

Those who are troubled by an apparent conflict between scientific and religious accounts of human origins may find it helpful to recall (Chapter 1) that different perspectives of life can be complementary. For example, the scientific account attempts to tell us when and how; religious creation stories usually aim to tell about an ultimate who and why. As Galileo explained to the Grand Duchess Christina, “The Bible teaches how to go to heaven, not how the heavens go.”

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72 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

CHAPTER REVIEW

The Biology of Behavior

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the chapter). Then turn to Appendix D, Complete Chapter Reviews, to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

Biology and Behavior 2-1: Why are psychologists concerned with human

biology?

Neural Communication 2-2: What are neurons, and how do they transmit

information?

2-3: How do nerve cells communicate with other nerve cells?

2-4: How do neurotransmitters influence behavior?

The Nervous System 2-5: What are the functions of the nervous system’s

main divisions, and what are the three main types of neurons?

The Endocrine System 2-6: How does the endocrine system transmit

information and interact with the nervous system?

The Brain 2-7: How do neuroscientists study the brain’s

connections to behavior and mind?

2-8: What structures make up the brainstem, and what are the functions of the brainstem, thalamus, and cerebellum?

2-9: What are the limbic system’s structures and functions?

2-10: What are the functions of the various cerebral cortex regions?

2-11: To what extent can a damaged brain reorganize itself, and what is neurogenesis?

2-12: What do split brains reveal about the functions of our two brain hemispheres?

LEARNING OBJECTIVES

dynamic entities that became conscious. Nature, says cosmologist Paul Davies (2007), seems cunningly and ingeniously devised to produce extraordinary, self-replicating, information-processing systems—us. Although we appear to have been created from dust, over eons of time, the end result is a priceless creature, one rich with potential beyond our imagining.

RETRIEVE IT

• Behavior geneticists are most interested in exploring

(commonalities; differences) in our traits and behaviors, and evolutionary psychologists are most interested in exploring

(commonalities; differences).

ANSWERS: differences; commonalities

ststtememem docrine system

eract with

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 73

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

1. The neuron fiber that passes messages through its branches to other neurons or to muscles and glands is the .

2. The tiny space between the axon of one neuron and the dendrite or cell body of another is called the

a. axon terminal. b. branching fiber.

c. synaptic gap. d. threshold.

3. Regarding a neuron’s response to stimulation, the intensity of the stimulus determines

a. whether or not an impulse is generated. b. how fast an impulse is transmitted. c. how intense an impulse will be. d. whether reuptake will occur.

4. In a sending neuron, when an action potential reaches an axon terminal, the impulse triggers the release of chemical messengers called .

EXPERIENCE THE TESTING EFFECT

Test yourself on these terms by trying to write down the definition in your own words before flip- ping back to the referenced page to check your answer.

biological psychology, p. 36

neuron, p. 36

dendrites, p. 36

axon, p. 36

myelin [MY-uh-lin] sheath, p. 37

glial cells (glia), p. 37

action potential, p. 37

threshold, p. 37

synapse [SIN-aps], p. 39

neurotransmitters, p. 39

endorphins [en - DOR-fins], p. 40

nervous system, p. 41

central nervous system (CNS), p. 41

peripheral nervous system (PNS), p. 41

nerves, p. 41

sensory (afferent) neurons, p. 41

motor (efferent) neurons, p. 41

interneurons, p. 41

somatic nervous system, p. 42

autonomic [aw - tuh - NAHM-ik] nervous system (ANS), p. 42

sympathetic nervous system, p. 42

parasympathetic nervous system, p. 42

reflex, p. 44

endocrine [EN-duh - krin] system, p. 45

hormones, p. 45

adrenal [ah - DREEN-el] glands, p. 45

pituitary gland, p. 45

lesion [LEE-zhuhn], p. 46

brainstem, p. 47

medulla [muh-DUL-uh], p. 47

electroencephalogram (EEG), p. 48

PET (positron emission tomography) scan, p. 48

MRI (magnetic resonance imaging), p. 48

fMRI (functional MRI), p. 48

thalamus [THAL-uh-muss], p. 48

reticular formation, p. 49

cerebellum [sehr - uh - BELL-um], p. 50

limbic system, p. 50

amygdala [uh - MIG-duh - la], p. 50

hypothalamus [hi - po - THAL-uh - muss], p. 51

cerebral [seh - REE-bruhl] cortex, p. 53

frontal lobes, p. 53

parietal [puh - RYE-uh - tuhl] lobes, p. 53

occipital [ahk - SIP-uh - tuhl] lobes, p. 53

temporal lobes, p. 53

motor cortex, p. 54

sensory cortex, p. 55

association areas, p. 56

plasticity, p. 57

neurogenesis, p. 58

corpus callosum [KOR-pus kah - LOW- sum], p. 59

split brain, p. 59

environment, p. 62

behavior genetics, p. 62

chromosomes, p. 62

DNA (deoxyribonucleic acid), p. 62

genes, p. 62

identical twins, p. 63

fraternal twins, p. 63

interaction, p. 67

epigenetics, p. 67

evolutionary psychology, p. 68

natural selection, p. 68

mutation, p. 69

TERMS AND CONCEPTS TO REMEMBER

Behavior Genetics: Predicting Individual Differences 2-13: What are genes, and how do behavior geneticists

explain our individual differences?

2-14: How do heredity and environment work together?

Evolutionary Psychology: Understanding Human Nature 2-15: How do evolutionary psychologists use natural

selection to explain behavior tendencies?

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74 CHAPTER 2 THE BIOLOGY OF BEHAVIOR

5. Endorphins are released in the brain in response to a. morphine or heroin. b. pain or vigorous exercise. c. the all-or-none response. d. All these answers are correct.

6. The autonomic nervous system controls internal functions, such as heart rate and glandular activity. The word autonomic means

a. calming. b. voluntary. c. self-regulating. d. arousing.

7. The sympathetic nervous system arouses us for action and the parasympathetic nervous system calms us down. Together, the two systems make up the nervous system.

8. The neurons of the spinal cord are part of the nervous system.

9. The most influential endocrine gland, known as the master gland, is the

a. pituitary. b. hypothalamus. c. thyroid. d. pancreas.

10. The secrete(s) epi- nephrine and norepinephrine, helping to arouse the body during times of stress.

11. The part of the brainstem that controls heartbeat and breath- ing is the

a. cerebellum. b. medulla. c. cortex. d. thalamus.

12. The thalamus functions like a(n) a. memory bank.

b. balance center. c. breathing regulator. d. Internet router.

13. The lower brain structure that governs arousal is the a. spinal cord. b. cerebellum. c. reticular formation. d. medulla.

14. The part of the brain that coordinates voluntary move- ment and enables nonverbal learning and memory is the .

15. Two parts of the limbic system are the amygdala and the a. cerebral hemispheres. b. hippocampus. c. thalamus. d. pituitary.

16. A cat’s ferocious response to electrical brain stimulation would lead you to suppose the electrode had touched the .

17. The neural structure that most directly regulates eating, drinking, and body temperature is the

a. endocrine system. b. hypothalamus. c. hippocampus. d. amygdala.

18. The initial reward center discovered by Olds and Milner was located in the .

19. If a neurosurgeon stimulated your right motor cortex, you would most likely

a. see light. b. hear a sound. c. feel a touch on the right arm. d. move your left leg.

20. How do different neural networks communicate with one another to let you respond when a friend greets you at a party?

21. Which of the following body regions has the greatest repre- sentation in the sensory cortex?

a. Upper arm b. Toes c. Lips d. All regions are equally represented.

22. The “uncommitted” areas that make up about three- fourths of the cerebral cortex are called .

23. Judging and planning are enabled by the lobes.

24. What would it be like to talk on the phone if you didn’t have temporal lobe association areas? What would you hear? What would you understand?

25. Plasticity is especially evident in the brains of a. split-brain patients. b. young adults. c. young children. d. right-handed people.

26. An experimenter flashes the word HERON across the visual field of a man whose corpus callosum has been sev-

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CHAPTER 2 THE BIOLOGY OF BEHAVIOR 75

ered. HER is transmitted to his right hemisphere and ON to his left hemisphere. When asked to indicate what he saw, the man says he saw but points to .

27. Studies of people with split brains and brain scans of those with undivided brains indicate that the left hemisphere excels in

a. processing language. b. visual perceptions. c. making inferences. d. neurogenesis.

28. Damage to the brain’s right hemisphere is most likely to reduce a person’s ability to

a. recite the alphabet rapidly. b. make inferences. c. understand verbal instructions. d. solve arithmetic problems.

29. What do behavior geneticists study?

30. The threadlike structures made largely of DNA molecules are called .

31. A small segment of DNA that codes for particular proteins is referred to as a .

32. When the mother’s egg and the father’s sperm unite, each contributes

a. one chromosome pair. b. 23 chromosomes. c. 23 chromosome pairs. d. 25,000 chromosomes.

33. Fraternal twins result when a. a single egg is fertilized by a single sperm and then splits. b. a single egg is fertilized by two sperm and then splits. c. two eggs are fertilized by two sperm. d. two eggs are fertilized by a single sperm.

34. twins share the same DNA.

35. Adoption studies seek to understand genetic influences on personality. They do this mainly by

a. comparing adopted children with nonadopted children. b. evaluating whether adopted children’s personalities more

closely resemble those of their adoptive parents or their biological parents.

c. studying the effect of prior neglect on adopted children. d. studying the effect of children’s age at adoption.

Find answers to these questions in Appendix E, in the back of the book.

Multiple-format self-tests and more may be found at www.worthpublishers.com/myers.

Experience more of the

TESTING EFFECT

E m

TE

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THE BRAIN AND CONSCIOUSNESS Dual Processing: The Two-Track Mind

Selective Attention

SLEEP AND DREAMS Biological Rhythms and Sleep

Sleep Theories

Sleep Deprivation and Sleep Disorders

Dreams

HYPNOSIS Frequently Asked Questions About Hypnosis

Explaining the Hypnotized State

DRUGS AND CONSCIOUSNESS Tolerance, Dependence, and Addiction

THINKING CRITICALLY ABOUT: Addiction

Types of Psychoactive Drugs

Influences on Drug Use

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77

Consciousness can be a funny thing. It offers us weird experiences, as when entering sleep or leaving a dream, and sometimes it leaves us wondering who

is really in control. After zoning me out with nitrous oxide, my dentist tells me to turn my head to the left. My conscious mind resists:

“No way,” I silently say. “You can’t boss me around!” Whereupon my robotic head, ignoring

my conscious mind, turns oblig- ingly under the dentist’s control.

Then there are those times when consciousness seems to

split. Reading Green Eggs and Ham to one of my preschoolers for the umpteenth time, my obliging

mouth could say the words while my mind wandered elsewhere. And if someone were to drop by my office while I’m typing this sentence, it would not be a problem. My fin-

gers could complete it as I strike up a conversation. What do such experiences reveal? Was my drug- induced dental experience akin to people’s experiences

with other psychoactive drugs (mood- and perception-altering substances)? Was my automatic obedience to my dentist like people’s responses to a hypnotist? Does a split in consciousness, as when our mind goes elsewhere while reading or typing, explain people’s behavior while under hypnosis? And during sleep, when do those weird dream experiences occur, and why? Before considering these questions and more, let’s ask a fundamental question: What is consciousness?

Consciousness and the Two-Track Mind

CHAPTERR3

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78 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

The Brain and Consciousness 3-1: What is the place of consciousness in psychology’s history?

Every science has concepts so fundamental they are nearly impossible to define. Biologists agree on what is alive but not on precisely what life is. In

physics, matter and energy elude simple definition. To psychologists, consciousness is simi- larly a fundamental yet slippery concept. At its beginning, psychology was “the description and explanation of states of consciousness” (Ladd, 1887). But during the first half of the twentieth century, the difficulty of scientifically studying consciousness led many psy- chologists—including those in the emerging school of behaviorism (Chapter 7)—to turn to direct observations of behavior. By the 1960s, psychology had nearly lost conscious- ness and was defining itself as “the science of behavior.” Consciousness was likened to a car’s speedometer: “It doesn’t make the car go, it just reflects what’s happening” (Selig- man, 1991, p. 24).

After 1960, mental concepts reemerged. Neuroscience advances linked brain activity to sleeping, dreaming, and other mental states. Researchers began studying conscious- ness altered by hypnosis and drugs. Psychologists of all persuasions were affirming the importance of cognition, or mental processes. Psychology was regaining consciousness.

Most psychologists now define consciousness as our awareness of ourselves and our environment. This awareness allows us to assemble information from many sources as we reflect on our past and plan for our future. And it focuses our attention when we learn a complex concept or behavior. When learning to drive, we focus on the car and the traf- fic. With practice, driving becomes semi-automatic, freeing us to focus our attention on other things. Over time, we flit between various states of consciousness, including normal waking awareness and various altered states (FIGURE 3.1).

Today’s science explores the biology of consciousness. Scientists now assume, in the words of neuroscientist Marvin Minsky (1986, p. 287), that “the mind is what the brain does.”

Evolutionary psychologists speculate that consciousness offers a reproductive advantage (Barash, 2006). By consider- ing consequences and helping us read others’ intentions, con- sciousness helps us act in our long-term interests. Even so, that

leaves us with the “hard problem”: How do brain cells jab- bering to one another create our awareness of the taste of a taco, the idea of infinity, the feeling of fright? Such questions are at the heart of cognitive neuroscience— the interdisciplinary study of the brain activity linked with

our mental processes. Based on your cortical activation patterns, neuroscientists can now, in limited ways, read your mind (Bor, 2010). They could tell, for example, which of 10 similar objects (hammer, drill, and so forth) you were viewing (Shinkareva

et al., 2008).

Some states occur spontaneously Daydreaming Drowsiness Dreaming

Some are physio- logically induced Hallucinations Orgasm

Food or oxygen starvation

Some are psycho- logically induced

Sensory deprivation Hypnosis Meditation

FIGURE 3.1

Altered states of consciousness In addition to normal, waking awareness, consciousness comes to us in altered states, including daydreaming, sleeping, meditating, and drug-induced hallucinating.

consciousness our awareness of ourselves and our environment.

cognitive neuroscience the interdis- ciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).

“Psychology must discard all reference to consciousness.”

Behaviorist John B. Watson (1913)

INSADCO Photography/Alamy

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 79

dual processing the principle that infor- mation is often simultaneously processed on separate conscious and unconscious tracks.

blindsight a condition in which a person can respond to a visual stimulus without consciously experiencing it.

Discovering which brain region becomes active with a particular conscious experi- ence strikes many people as interesting but not mind blowing. (If everything psycho- logical is simultaneously biological, then our ideas, emotions, and spirituality must all, somehow, be embodied.) What is mind blowing to many of us is the growing evidence that we have, so to speak, two minds, each supported by its own neural equipment.

RETRIEVE IT

• Those working in the interdisciplinary field called

study the brain activity associated with perception, thinking, memory, and language.

ANSWER: cognitive neuroscience

Dual Processing: The Two-Track Mind

3-2: What is the “dual-processing” being revealed by today’s cognitive neuroscience?

At any moment, you and I are aware of little more than what’s on the screen of our consciousness. But beneath the surface, unconscious information processing occurs simultaneously on many parallel tracks. When we look at a bird flying, we are consciously aware of the result of our cognitive processing (“It’s a hummingbird!”) but not of our subprocessing of the bird’s color, form, movement, and distance. One of the grand ideas of recent cognitive neuroscience is that much of our brain work occurs off stage, out of sight. Perception, memory, thinking, language, and attitudes all operate on two levels—a conscious, deliberate “high road,” and an unconscious, automatic “low road.” Today’s researchers call this dual processing. We know more than we know we know.

If you are a driver, consider how you move into a right lane. Drivers know this unconsciously, yet they cannot accurately explain it (Eagleman, 2011). Can you? Most say they would bank the steering wheel to the right, then straighten it out—a procedure that would actually steer them off the road. In reality, an experienced driver, after mov- ing right, automatically reverses the wheel just as far to the left of center, and only then returns to the center position. The lesson: The human brain is a device for converting conscious into unconscious knowledge.

Or consider this story, which illustrates how science can be stranger than science fic- tion. During my sojourns at Scotland’s University of St. Andrews, I came to know cogni- tive neuroscientists David Milner and Melvyn Goodale (2008). A local woman, whom they called D. F., had suffered brain damage when overcome by carbon monoxide, leav- ing her unable to recognize and discriminate objects visually. Consciously, D. F. could see nothing. Yet she exhibited blindsight—she acted as though she could see. Asked to slip a postcard into a vertical or horizontal mail slot, she could do so without error. Asked the width of a block in front of her, she was at a loss, but she could grasp it with just the right finger-thumb distance.

How could this be? Don’t we have one visual system? Goodale and Milner knew from animal research that the eye sends information simultaneously to different brain areas, which support different tasks (Weiskrantz, 2009, 2010). Sure enough, a scan of D.F.’s brain activity revealed normal activity in the area concerned with reaching for, grasping, and navigating objects, but damage in the area concerned with consciously recognizing objects. (See another example in FIGURE 3.2.)

How strangely intricate is this thing we call vision, conclude Goodale and Milner in their aptly titled book, Sight Unseen. We may think of our vision as one system con- trolling our visually guided actions, but it is actually a dual-processing system. A visual perception track enables us “to think about the world”—to recognize things and to plan future actions. A visual action track guides our moment-to-moment movements.

FIGURE 3.2

When the blind can “see” In this compelling demonstration of blindsight and the two-track mind, researcher Lawrence Weiskrantz trailed a blindsight patient down a cluttered hallway. Although told the hallway was empty, the patient meandered around all the obstacles without any awareness of them.

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80 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

The dual-track mind can also be seen in a patient who lost all his left visual cortex, leaving him blind to objects presented on the right side of his field of vision. He is nev- ertheless able to sense the emotion expressed in faces, presented to his right, he does not consciously perceive (De Gelder, 2010). The same is true of normally sighted people whose visual cortex has been disabled with magnetic stimulation. Such findings suggest that brain areas below the cortex are processing emotion-related information.

People often have trouble accepting that much of our everyday thinking, feeling, and acting operates outside our conscious awareness (Bargh & Chartrand, 1999). We are understandably biased to believe that our intentions and deliberate choices rule our lives. But consciousness, though enabling us to exert voluntary control and to communicate our mental states to others, is but the tip of the information - processing iceberg. Being intensely focused on an activity (such as reading this chapter, I’d love to think) increases your total brain activity no more than 5 percent above its baseline rate. And even when you rest, “hubs of dark energy” are whirling inside your head (Raichle, 2010).

Unconscious parallel processing is faster than conscious sequential processing, but both are essential. Parallel processing enables your mind to take care of routine business. Sequential processing is skilled at solving new problems, which requires your focused attention. Try this: If you are right - handed, you can move your right foot in a smooth counterclockwise circle, and you can write the number 3 repeatedly with your right hand—but probably not at the same time. (If you are musically inclined, try something equally difficult: Tap a steady beat three times with your left hand while tapping four times with your right hand.) Both tasks require conscious attention, which can be in only one place at a time. If time is nature’s way of keeping everything from happening at once, then consciousness is nature’s way of keeping us from thinking and doing everything at once.

RETRIEVE IT

• What are the mind’s two tracks, and what is “dual processing”?

ANSWER: Our mind has separate conscious and unconscious tracks that perform dual processing—organizing and interpreting information simultaneously.

Selective Attention

3-3: How much information do we consciously attend to at once?

Through selective attention, your awareness focuses, like a flashlight beam, on a minute aspect of all that you experience. By one estimate, your five senses

take in 11,000,000 bits of information per second, of which you consciously process about 40 (Wilson, 2002). Yet your mind’s unconscious track intuitively makes great use of the other 10,999,960 bits. Until reading this sentence, for example, you have been unaware that your shoes are pressing against your feet or that your nose is in your line of vision. Now, suddenly, your attentional spotlight shifts. Your feet feel encased, your nose stubbornly intrudes on the words before you. While focusing on these words, you’ve also been blocking other parts of your environment from awareness, though your peripheral vision would let you see them easily. You can change that. As you stare at the X below, notice what surrounds these sentences (the edges of the page, the desktop, the floor).

X A classic example of selective attention is the cocktail party effect—your ability to attend

to only one voice among many. Let another voice speak your name and your cognitive radar, operating on your mind’s other track, will instantly bring that voice into con- sciousness. This effect might have prevented an embarrassing and dangerous situation in 2009, when two Northwest Airlines pilots “lost track of time.” Focused on their laptops and conversation, they ignored alarmed air traffic controllers’ attempts to reach them as they overflew their Minneapolis destination by 150 miles. If only the controllers had known and spoken the pilots’ names.

“Has a generation of texters, surfers, and twitterers evolved the enviable ability to process multiple streams of novel information in parallel? Most cognitive psychologists doubt it.”

Steven Pinker, “Not at All,” 2010

selective attention the focusing of con- scious awareness on a particular stimulus.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 81

inattentional blindness failing to see visible objects when our attention is directed elsewhere.

“I wasn’t texting. I was building this ship in a bottle.”

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Selective Attention and Accidents Talk on the phone or attend to a music player or GPS while driving and your selective attention will shift back and forth between the road and its electronic competition. But when a demanding situation requires it, you’ll probably give the road your full atten- tion. You’ll probably also blink less. When focused on a task, such as reading, people blink less than when their mind is wandering (Smilek et al., 2010). If you want to know whether your dinner companion is focused on what you’re saying, watch for eyeblinks and hope there won’t be too many.

We pay a toll for switching attentional gears, especially when we shift to complex tasks, like noticing and avoiding cars around us. The toll is a slight and sometimes fatal delay in coping (Rubenstein et al., 2001). About 28 percent of traffic accidents occur when people are chatting on cell phones or texting (National Safety Council, 2010). One study tracked long-haul truck drivers for 18 months. The video cameras mounted in their cabs showed they were at 23 times greater risk of a collision while texting (VTTI, 2009). Mindful of such findings, the United States in 2010 banned truckers and bus drivers from texting while driving (Halsey, 2010).

It’s not just truck drivers who are at risk. One in four teen drivers with cell phones admit to texting while driving (Pew, 2009). Multitasking comes at a cost: fMRI scans offer a biological account of how multitasking distracts from brain resources allocated to driving. In areas vital to driving, brain activity decreases an average 37 percent when a driver is attending to conversation (Just et al., 2008).

Even hands-free cell-phone talking is more distracting than chatting with passengers, who can see the driving demands and pause the conversation. When University of Syd- ney researchers analyzed phone records for the moments before a car crash, they found that cell-phone users (even those with hands-free sets) were four times more at risk (McEvoy et al., 2005, 2007). Having a passenger increased risk only 1.6 times. This risk difference also appeared in an experiment that asked drivers to pull off at a freeway rest stop 8 miles ahead. Of drivers conversing with a passenger, 88 percent did so. Of those talking on a cell phone, 50 percent drove on by (Strayer & Drews, 2007).

Sally Forth

Driven to distraction In driving- simulation experiments, people whose attention is diverted by cell- phone conversation make more driving errors.

Selective Inattention At the level of conscious awareness, we are “blind” to all but a tiny sliver of visual stim- uli. Ulric Neisser (1979), Robert Becklen and Daniel Cervone (1983) demonstrated this inattentional blind ness dramatically. They showed people a one - minute video in which images of three black-shirted men tossing a basketball were superimposed over the images of three white-shirted players. The viewers’ supposed task was to press a key every time a black- shirted player passed the ball. Most focused their attention so completely on the game that they failed to notice a young woman carrying an umbrella saunter across the screen midway through the video. Seeing a replay of the video, viewers were astonished to see her (Mack & Rock, 2000). This inattentional blindness is a by-product of what we are really good at: focusing attention on some part of our environment.

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82 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

In a repeat of the experiment, smart-aleck researchers Daniel Simons and Christopher Chabris (1999) sent a gorilla - suited assistant through a swirl of players (FIGURE 3.3). During its 5- to 9-second cameo appearance, the gorilla paused to thump its chest. Still, half the conscientious pass - counting view- ers failed to see it. In another follow- up experiment, only 1 in 4 students engrossed in a cell-phone conversation while crossing a campus square noticed

a a clown-suited unicyclist in their midst (Hyman et al., 2010). (Most of those not on the phone did notice.) Atten- tion is powerfully selective. Your con- scious mind is in one place at a time.

Given that most people miss some- one in a gorilla suit while their attention is riveted elsewhere, imagine the fun that magicians can have by manipulating our selective attention. Misdirect people’s attention and they will miss the hand slipping into the pocket. “Every time you perform a magic trick, you’re engaging in experimental psychology,” says magician Teller, a master of mind-messing methods (2009).

FIGURE 3.3

Gorilla in our midst When attending to one task (counting basketball passes by one of the three - person teams), about half the viewers displayed inattentional blindness by failing to notice a clearly visible gorilla passing through.

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Magicians also exploit our change blindness. By selectively riveting our attention on their left hand’s dramatic act, they entice us to overlook changes made with their other hand. Participants in laboratory experiments on change blindness have failed to

notice that, after a brief visual interruption, a big Coke bottle had disappeared, a railing had risen, or clothing color had changed (Chabris & Simons, 2010; Resnick et al., 1997). Two-thirds of those who were focused on giv- ing directions to a construction worker failed to notice when he was replaced by another worker during a staged interruption (FIGURE 3.4). Out of sight, out of mind.

Some stimuli, however, are so powerful, so strikingly distinct, that we experience pop out, as with the only smil- ing face in FIGURE 3.5. We don’t choose to attend to these stimuli; they draw our eye and demand our attention.

The dual-track mind is active even during sleep, as we see next. ©

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Change blindness While a man (white hair) provides directions to a construction worker, two experimenters rudely pass between them carrying a door. During this interruption, the original worker switches places with another person wearing different-colored clothing. Most people, focused on their direction giving, do not notice the switch. (From Simons & Levin, 1998.)

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 83

Sleep and Dreams Sleep—the irresistible tempter to whom we inevitably succumb. Sleep—the equalizer of presidents and peasants. Sleep—sweet, renewing, mysterious sleep. While sleeping, you may feel “dead to the world,” but you are not. Even when you are deeply asleep, your perceptual window is open a crack. You move around on your bed, but you man- age not to fall out. The occasional roar of passing vehicles may leave your deep sleep undisturbed, but a cry from a baby’s nursery quickly interrupts it. So does the sound of your name. EEG recordings confirm that the brain’s auditory cortex responds to sound stimuli even during sleep (Kutas, 1990). And when you are asleep, as when you are awake, you process most information outside your conscious awareness.

Many of sleep’s mysteries are now being solved as some people sleep, attached to recording devices, while others observe. By recording brain waves and muscle move- ments, and by observing and occasionally waking sleepers, researchers are glimpsing things that a thousand years of common sense never told us. Perhaps you can anticipate some of their discoveries. Are the following statements true or false?

1. When people dream of performing some activity, their limbs often move in concert with the dream.

2. Older adults sleep more than young adults.

3. Sleepwalkers are acting out their dreams.

4. Sleep experts recommend treating insomnia with an occasional sleeping pill.

5. Some people dream every night; others seldom dream.

All these statements (adapted from Palladino & Carducci, 1983) are false. To see why, read on.

Biological Rhythms and Sleep Like the ocean, life has its rhythmic tides. Over varying time periods, our bodies fluc- tuate, and with them, our minds. Let’s look more closely at two of those biological rhythms—our 24-hour biological clock and our 90-minute sleep cycle.

Circadian Rhythm

3-4: How do our biological rhythms influence our daily functioning?

The rhythm of the day parallels the rhythm of life—from our waking at a new day’s birth to our nightly return to what Shakespeare called “death’s counterfeit.” Our bodies roughly syn- chronize with the 24-hour cycle of day and night by an internal biological clock called the circadian rhythm (from the Latin circa, “about,” and diem, “day”). As morning approaches, body temperature rises, then peaks during the day, dips for a time in early afternoon (when many people take siestas), and begins to drop again in the evening. Thinking is sharpest and memory most accurate when we are at our daily peak in circadian arousal. Try pulling an all - nighter or working an occasional night shift. You’ll feel groggiest in the middle of the night but may gain new energy when your normal wake - up time arrives.

Age and experience can alter our circadian rhythm. Most 20-year-olds are evening- energized “owls,” with performance improving across the day (May & Hasher, 1998).

“I love to sleep. Do you? Isn’t it great? It really is the best of both worlds. You get to be alive and unconscious.”

Comedian Rita Rudner, 1993

change blindness failing to notice changes in the environment.

circadian [ser - KAY-dee - an] rhythm the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.

Eric Isselée/Shutterstock

Dolphins, porpoises, and whales sleep with one side of their brain at a time (Miller et al., 2008).

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84 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Left eye movements

Right eye movements

EMG (muscle tension)

EEG (brain waves)

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Measuring sleep activity Sleep researchers measure brain - wave activity, eye movements, and muscle tension by electrodes that pick up weak electrical signals from the brain, eyes, and facial muscles. (From Dement, 1978.)

Most older adults are morning-loving “larks,” with performance declining as the day wears on. By mid-evening, when the night has hardly begun for many young adults, retirement homes are typically quiet. After about age 20 (slightly earlier for women), we begin to shift from being owls to being larks (Roenneberg et al., 2004). Women become more morn- ing oriented as they have children and also as they transition to menopause (Leonhard & Randler, 2009; Randler & Bausback, 2010). Morning types tend to do better in school, to take more initiative, and to be less vulnerable to depression (Randler, 2008, 2009; Randler & Frech, 2009).

Sleep Stages

3-5: What is the biological rhythm of our sleeping and dreaming stages?

Sooner or later, sleep overtakes us and consciousness fades as different parts of our brain’s cortex stop communicating (Massimini et al., 2005). But rather than emitting a constant dial tone, the sleeping brain has its own biological rhythm.

About every 90 minutes, you cycle through four distinct sleep stages. This simple fact apparently was unknown until 8-year - old Armond Aserinsky went to bed one night in 1952. His father, Eugene, a University of Chicago graduate student, needed to test an electroencephalograph he had repaired that day (Aserinsky, 1988; Seligman & Yellen, 1987). Placing electrodes near Armond’s eyes to record the rolling eye movements then believed to occur during sleep, Aserinsky watched the machine go wild, tracing deep zigzags on the graph paper. Could the machine still be broken? As the night proceeded and the activity recurred, Aserinsky realized that the periods of fast, jerky eye move- ments were accompanied by energetic brain activity. Awakened during one such epi- sode, Armond reported having a dream. Aserinsky had discovered what we now know as REM sleep (rapid eye movement sleep).

Similar procedures used with thousands of volunteers showed the cycles were a normal part of sleep (Kleitman, 1960). To appreciate these studies, imagine yourself as a participant. As the hour grows late, you feel sleepy and yawn in response to reduced brain metabolism. (Yawning, which can be socially contagious, stretches your neck muscles and increases your heart rate, which increases your alertness [Moorcroft, 2003].) When you are ready for bed, a researcher comes in and tapes electrodes to your scalp (to detect your brain waves), on your chin (to detect muscle tension), and just outside the corners of your eyes (to detect eye movements) (FIGURE 3.6). Other devices will record your heart rate, respiration rate, and genital arousal.

Peter Chadwick/Photo Researchers, Inc.

REM sleep rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.

alpha waves the relatively slow brain waves of a relaxed, awake state.

sleep periodic, natural loss of conscious- ness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.)

hallucinations false sensory experiences, such as seeing something in the absence of an external visual stimulus.

delta waves the large, slow brain waves associated with deep sleep.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 85

When you are in bed with your eyes closed, the researcher in the next room sees on the EEG the relatively slow alpha waves of your awake but relaxed state (FIGURE 3.7). As you adapt to all this equipment, you grow tired and, in an unremembered moment, slip into sleep (FIGURE 3.8). The transition is marked by the slowed breathing and the irregular brain waves of non-REM stage 1 sleep. Using the new American Academy of Sleep Medi- cine classification of sleep stages, this is called NREM-1 sleep (Silber et al., 2008).

In one of his 15,000 research partici- pants, William Dement (1999) observed the moment the brain’s perceptual window to the outside world slammed shut. Dement asked this sleep - deprived young man, lying on his back with eyelids taped open, to press a button every time a strobe light flashed in his eyes (about every 6 seconds). After a few min- utes the young man missed one. Asked why, he said, “Because there was no flash.” But there was a flash. He missed it because (as his brain activity revealed) he had fallen asleep for 2 seconds, missing not only the flash 6 inches from his nose but also the awareness of the abrupt moment of entry into sleep.

During this brief NREM-1 sleep you may experience fantastic images resembling hallucinations—sensory experiences that occur without a sensory stimulus. You may have a sensation of falling (at which moment your body may suddenly jerk) or of float- ing weightlessly. These hypnagogic sensations may later be incorporated into your memo- ries. People who claim to have been abducted by aliens—often shortly after getting into bed—commonly recall being floated off (or pinned down on) their beds (Clancy, 2005).

You then relax more deeply and begin about 20 minutes of NREM-2 sleep, with its periodic sleep spindles—bursts of rapid, rhythmic brain- wave activity (see Figure 3.7). Although you could still be awakened without too much difficulty, you are now clearly asleep.

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To catch your own hypnagogic experiences, you might use your alarm’s snooze function.

Then you transition to the deep sleep of NREM-3. During this slow - wave sleep, which lasts for about 30 minutes, your brain emits large, slow delta waves and you are hard to awaken. (It is at the end of the deep, slow-wave NREM-3 sleep that children may wet the bed.)

REM Sleep About an hour after you first fall asleep, a strange thing happens. Rather than con- tinuing in deep slumber, you ascend from your initial sleep dive. Returning through NREM-2 (where you spend about half your night), you enter the most intriguing sleep phase—REM sleep (FIGURE 3.9 on the next page). For about 10 minutes, your brain waves become rapid and saw - toothed, more like those of the nearly awake NREM-1 sleep. But unlike NREM-1, during REM sleep your heart rate rises, your

FIGURE 3.7

Brain waves and sleep stages The beta waves of an alert, waking state and the regular alpha waves of an awake, relaxed state differ from the slower, larger delta waves of deep NREM-3 sleep. Although the rapid REM sleep waves resemble the near- waking NREM-1 sleep waves, the body is more aroused during REM sleep than during NREM sleep.

,

FIGURE 3.8

The moment of sleep We seem unaware of the moment we fall into sleep, but someone watching our brain waves could tell. (From Dement, 1999.)

People rarely snore during dreams. When REM starts, snoring stops.

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86 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

breathing becomes rapid and irregular, and every half - minute or so your eyes dart around in momen- tary bursts of activity behind closed lids. These eye movements announce the beginning of a dream— often emotional, usually story-like, and richly hal- lucinatory. Because anyone watching a sleeper’s eyes can notice these REM bursts, it is amazing that sci- ence was ignorant of REM sleep until 1952.

Except during very scary dreams, your genitals become aroused during REM sleep. You have an erection or increased vaginal lubrication and clito- ral engorgement, regardless of whether the dream’s content is sexual (Karacan et al., 1966). Men’s com- mon “morning erection” stems from the night’s last REM period, often just before waking. In young men, sleep - related erections outlast REM periods,

lasting 30 to 45 minutes on average (Karacan et al., 1983; Schiavi & Schreiner - Engel, 1988). A typical 25-year- old man therefore has an erection during nearly half his night’s sleep, a 65-year - old man for one - quarter. Many men troubled by erectile dysfunc- tion (impotence) have sleep-related erections, suggesting the problem is not between their legs.

Your brain’s motor cortex is active during REM sleep, but your brainstem blocks its messages. This leaves your muscles relaxed, so much so that, except for an occasional finger, toe, or facial twitch, you are essentially paralyzed. Moreover, you cannot easily be awakened. REM sleep is thus sometimes called paradoxical sleep: The body is internally aroused, with waking-like brain activity, yet asleep and externally calm.

Hours of sleep

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FIGURE 3.9

The stages in a typical night’s sleep People pass through a multistage sleep cycle several times each night, with the periods of deep sleep diminishing and REM sleep periods increasing in duration. As people age, sleep becomes more fragile, with awakenings common among older adults (Kamel et al., 2006; Neubauer, 1999).

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 87

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RETRIEVE IT

• Why would communal sleeping provide added protection for those whose safety depends upon vigilance, such as these soldiers?

ANSWER: With each soldier cycling through the sleep stages independently, it is very likely that at any given time at least one of them will be awake or easily wakened in the event of a threat.

The sleep cycle repeats itself about every 90 minutes for younger adults (somewhat more frequently for older adults). As the night wears on, deep NREM-3 sleep grows shorter and disappears. The REM and NREM-2 sleep periods get longer (see Figure 3.9). By morning, we have spent 20 to 25 percent of an average night’s sleep—some 100 minutes—in REM sleep. Thirty - seven percent of people report rarely or never having dreams “that you can remember the next morning” (Moore, 2004). Yet even they will, more than 80 percent of the time, recall a dream after being awakened during REM sleep. We spend about 600 hours a year experiencing some 1500 dreams, or more than 100,000 dreams over a typical lifetime—dreams swallowed by the night but not acted out, thanks to REM’s protective paralysis.

RETRIEVE IT

• What are the four sleep stages, and in what order do we normally travel through those stages?

• Can you match the cognitive experience with the sleep stage?

1. NREM-1 a. story-like dreams

2. NREM-3 b. fleeting images

3. REM c. minimal awareness ANSWERS: 1. b, 2. c, 3. a

ANSWER: REM, NREM-1, NREM-2, NREM-3; normally we move through NREM-1, then NREM-2, then NREM-3, then back up through NREM-2 before we experience REM sleep.

What Affects Our Sleep Patterns?

3-6: How do biology and environment interact in our sleep patterns?

The idea that “everyone needs 8 hours of sleep” is untrue. Newborns sleep nearly two- thirds of their day, most adults no more than one - third. Still, there is more to our sleep differences than age. Some of us thrive with fewer than 6 hours per night; others regularly rack up 9 hours or more. Such sleep patterns are genetically influenced (Hor & Tafti, 2009). In studies of fraternal and identical twins, only the identical twins had strikingly similar sleep patterns and durations (Webb & Campbell, 1983). Today’s researchers are discovering the genes that regulate sleep in humans and animals (Donlea et al., 2009; He et al., 2009).

In the United States and Canada, adults average 7 to 8 hours of sleep per night (Hurst, 2008; National Sleep Foundation, 2010; Robinson & Martin, 2009). North Americans are nevertheless sleeping less than their counterparts a century ago. Thanks to modern light bulbs, shift work, and social diversions, those who would have gone to bed at 9:00 P.M. are now up until 11:00 P.M. or later. With sleep, as with waking behavior, biology and environment interact.

Being bathed in light disrupts our 24-hour biological clock (Czeisler et al., 1999; Dement, 1999). Bright light affects our sleepiness by activating light-sensitive retinal proteins. This signals the brain’s suprachiasmatic nucleus to decrease production of melatonin, a sleep-inducing hormone (FIGURE 3.10). Our ancestors’ body clocks were

Melatonin produced

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Pineal gland

Light

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suprachiasmatic nucleus a pair of cell clusters in the hypothalamus that responds to light-sensitive retinal proteins; causes pineal gland to increase or decrease production of mela- tonin, thus modifying our feelings of sleepiness.

FIGURE 3.10

The biological clock Light striking the retina signals the suprachiasmatic nucleus (SCN) to suppress the pineal gland’s production of the sleep hormone melatonin. At night, the SCN quiets down, allowing the pineal gland to release melatonin into the bloodstream.

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88 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

20 Hours20 Hours 16 Hours16 Hours 12 Hours12 Hours 10 Hours10 Hours 8 Hours8 Hours 4 Hours4 Hours 2 hours2 hours

FIGURE 3.11

Animal sleep times Would you rather be a brown bat and sleep 20 hours a day or a giraffe and sleep 2 hours (data from NIH, 2010)?

Kruglov_Orda/Shutterstock; Courtesy of Andrew D. Myers; © Anna63/Dreamstime.com; Steffen Foerster Photography/

Shutterstock; The Agency Collection/Punchstock; Eric Isselée/Shutterstock; pandapaw/Shutterstock

attuned to the rising and setting Sun of the 24-hour day. Many of today’s young adults adopt something closer to a 25-hour day, by staying up too late to get 8 hours of sleep. Most animals, too, when placed under unnatural constant illumination will exceed a 24-hour day.

Sleep often eludes those who stay up late and sleep in on weekends, and then go to bed earlier on Sunday to prepare for the new week ahead (Oren & Terman, 1998). For North Americans who fly to Europe and need to be up when their circadian rhythm cries “SLEEP,” bright light (spending the next day outdoors) helps reset the biological clock (Czeisler et al., 1986, 1989; Eastman et al., 1995).

RETRIEVE IT

• The

nucleus helps monitor the brain’s release of melatonin, which affects our

rhythm.

ANSWERS: suprachiasmatic nucleus; circadian

Sleep Theories

3-7: What are sleep’s functions?

So, our sleep patterns differ from person to person and from culture to cul- ture. But why do we have this need for sleep? Psychologists offer five possible

reasons why sleep evolved.

1. Sleep protects. When darkness shut down the day’s hunting, food gathering, and travel, our distant ancestors were better off asleep in a cave, out of harm’s way. Those who didn’t try to navigate around rocks and cliffs at night were more likely to leave descen- dants. This fits a broader principle: A species’ sleep pattern tends to suit its ecological niche (Siegel, 2009). Animals with the greatest need to graze and the least ability to hide tend to sleep less. (For a sampling of animal sleep times, see FIGURE 3.11.)

2. Sleep helps us recuperate. It helps restore and repair brain tissue. Bats and other ani- mals with high waking metabolism burn a lot of calories, producing a lot of free radi- cals, molecules that are toxic to neurons. Sleeping a lot gives resting neurons time to repair themselves, while pruning or weakening unused connections (Gilestro et al., 2009; Siegel, 2003; Vyazovskiy et al., 2008). Think of it this way: When conscious- ness leaves your house, brain construction workers come in for a makeover.

3. Sleep helps restore and rebuild our fading memories of the day’s experiences. Sleep consolidates our memories —it strengthens and stabilizes neural memory traces (Rac- smány et al., 2010; Rasch & Born, 2008). People trained to perform tasks therefore recall them better after a night’s sleep, or even after a short nap, than after several hours awake (Stickgold & Ellenbogen, 2008). After sleeping well, older people remember more. And in both humans and rats, neural activity during slow - wave sleep re-enacts and promotes recall of prior novel experiences (Peigneux et al., 2004; Ribeiro et al., 2004). Sleep, it seems, strengthens memories in a way that being awake does not.

4. Sleep feeds creative thinking. On occasion, dreams have inspired noteworthy literary, artistic, and scientific achievements, such as the dream that clued chemist August Kekulé to the structure of benzene (Ross, 2006). More commonplace is the boost that a complete night’s sleep gives to our thinking and learning. After working on a task, then sleeping on it, people solve problems more insightfully than do those who

“Sleep faster, we need the pillows.”

Yiddish proverb

“Corduroy pillows make headlines.”

Anonymous

A circadian disadvantage: One study of a decade’s 24,121 Major League Baseball games found that teams who had crossed three time zones before playing a multiday series had nearly a 60 percent chance of losing their first game (Winter et al., 2009).

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 89

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“Maybe ‘Bring Your Pillow To Work Day’ wasn’t such a good idea.”

stay awake (Wagner et al., 2004). They also are better at spotting connections among novel pieces of information (Ellenbogen et al., 2007). To think smart and see connec- tions, it often pays to sleep on it.

5. Sleep supports growth. During deep sleep, the pituitary gland releases a growth hor- mone necessary for muscle development. A regular full night’s sleep can also “dramati- cally improve your athletic ability,” report James Maas and Rebecca Robbins (2010). Well-rested athletes have faster reaction times, more energy, and greater endurance. Teams that build 8 to 10 hours of daily sleep into their training show improved per- formance. As we age, we release less of this hormone and spend less time in deep sleep (Pekkanen, 1982).

Given all the benefits of sleep, it’s no wonder that sleep loss hits us so hard.

RETRIEVE IT

• What five theories explain our need for sleep?

ANSWER: (1) Sleep has survival value. (2) Sleep helps restore and repair brain tissue. (3) During sleep we strengthen memory traces. (4) Sleep fuels creativity. (5) Sleep plays a role in the growth process.

Sleep Deprivation and Sleep Disorders

3-8: How does sleep loss affect us, and what are the major sleep disorders?

When our body yearns for sleep but does not get it, we begin to feel terrible. Trying to stay awake, we will eventually lose. In the tiredness battle, sleep always wins.

Effects of Sleep Loss Today, more than ever, our sleep patterns leave us not only sleepy but drained of energy and feelings of well-being. After a succession of 5-hour nights, we accumulate a sleep debt that need not be entirely repaid but cannot be satisfied by one long sleep. “The brain keeps an accurate count of sleep debt for at least two weeks,” reported sleep researcher William Dement (1999, p. 64).

Obviously, then, we need sleep. Sleep commands roughly one - third of our lives— some 25 years, on average. Allowed to sleep unhindered, most adults will sleep at least 9 hours a night (Coren, 1996). With that much sleep, we awake refreshed, sustain better moods, and perform more efficient and accurate work. The U.S. Navy and the National Institutes of Health have demonstrated the benefits of unrestricted sleep in experiments in which volunteers spent 14 hours daily in bed for at least a week. For the first few days, the volunteers averaged 12 hours of sleep a day or more, apparently paying off a sleep debt that averaged 25 to 30 hours. That accomplished, they then settled back to 7.5 to 9 hours nightly and felt energized and happier (Dement, 1999). In one Gallup survey (Mason, 2005), 63 percent of adults who reported getting the sleep they needed also reported being “very satisfied” with their personal life (as did only 36 percent of those needing more sleep).

College and university students are especially sleep deprived; 69 percent in one national survey reported “feeling tired” or “having little energy” on several or more days in the last two weeks (AP, 2009). In another survey, 28 percent of high school students acknowledged falling asleep in class at least once a week (Sleep Foundation, 2006). When the going gets boring, the students start snoring.

Sleep loss is a predictor of depression. Researchers who studied 15,500 young people, 12 to 18 years old, found that those who slept 5 or fewer hours a night had a 71 per- cent higher risk of depression than their peers who slept 8 hours or more (Gangwisch et al., 2010). This link does not appear to reflect sleep difficulties caused by depression.

In 1989, Michael Doucette was named America’s Safest Driving Teen. In 1990, while driving home from college, he fell asleep at the wheel and collided with an oncoming car, killing both himself and the other driver. Michael’s driving instructor later acknowledged never having mentioned sleep deprivation and drowsy driving (Dement, 1999).

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When children and youth are followed through time, sleep loss predicts depression rather than vice versa (Gregory et al., 2009). Moreover, REM sleep’s processing of emotional experiences helps protect against depression (Walker & van der Helm, 2009). After a good night’s sleep, we often do feel better the next day. And that may help to explain why parentally enforced bedtimes predict less depression, and why pushing back school start time leads to improved adolescent sleep, alertness, and mood (Gregory et al., 2009; Owens et al., 2010).

Sleep-deprived students often function below their peak. And they know it: Four in five teens and three in five 18- to 29-year - olds wish they could get more sleep on week- days (Mason, 2003, 2005). Yet that teen who staggers glumly out of bed in response to an unwelcome alarm, yawns through morning classes, and feels half - depressed much of the day may be energized at 11:00 P.M. and mindless of the next day’s looming sleepiness (Carskadon, 2002). “Sleep deprivation has consequences—difficulty study- ing, diminished productivity, tendency to make mistakes, irritability, fatigue,” noted Dement (1999, p. 231). A large sleep debt “makes you stupid.”

It can also make you gain weight. Sleep deprivation increases ghrelin, a hunger- arousing hormone, and decreases its hunger-suppressing partner, leptin (more on these in Chapter 10). It also increases cortisol, a stress hormone that stimulates the body to make fat. Sure enough, children and adults who sleep less than normal are fatter than those who sleep more (Chen et al., 2008; Knutson et al., 2007; Schoenborn & Adams, 2008). And experimental sleep deprivation of adults increases appetite and eating (Nixon et al., 2008; Patel et al., 2006; Spiegel et al., 2004; Van Cauter et al., 2007). This may help explain the common weight gain among sleep-deprived students (although a review of 11 studies reveals that the mythical “freshman 15” is, on average, closer to a “first-year 4” [Hull et al., 2007]).

Sleep affects our immune system. When infections set in, we typically sleep more, boosting our immune cells. Sleep deprivation can suppress the immune cells that battle viral infections and cancer (Motivala & Irwin, 2007). In one experiment, when researchers exposed volunteers to a cold virus, those who had been averaging less than 7 hours sleep a night were three times more likely to develop the cold than were those sleeping 8 or more hours a night (Cohen et al., 2009). Sleep’s protective effect may help explain why people who sleep 7 to 8 hours a night tend to outlive those who are chronically sleep deprived, and why older adults who have no difficulty falling or stay- ing asleep tend to live longer than their sleep-deprived agemates (Dement, 1999; Dew et al., 2003).

Sleep deprivation slows reactions and increases errors on visual attention tasks similar to those involved in screening airport baggage, performing surgery, and reading X-rays (Lim & Dinges, 2010). When sleepy frontal lobes confront an unexpected situation, mis- fortune often results. Consider the timing of the 1989 Exxon Valdez oil spill; Union Car- bide’s 1984 Bhopal, India, disaster; and the 1979 Three Mile Island and 1986 Chernobyl nuclear accidents: All occurred after midnight, when operators in charge were likely to be drowsiest and unresponsive to signals requiring an alert response. Slow responses can also spell disaster for those operating equipment, piloting, or driving. Driver fatigue has contributed to an estimated 20 percent of American traffic accidents (Brody, 2002) and to some 30 percent of Australian highway deaths (Maas, 1999).

Stanley Coren capitalized on what is, for many North Americans, a semi - annual sleep- manipulation experiment—the “spring forward” to “daylight savings” time and “fall backward” to “standard” time. Searching millions of records, Coren found that in both Canada and the United States, accidents increased immediately after the time change that shortens sleep (FIGURE 3.12).

FIGURE 3.13 summarizes the effects of sleep deprivation. But there is good news! Psychologists have discovered a treatment that strengthens memory, increases concentra- tion, boosts mood, moderates hunger and obesity, fortifies the disease - fighting immune system, and lessens the risk of fatal accidents. Even better news: The treatment feels

insomnia recurring problems in falling or staying asleep.

“Remember to sleep because you have to sleep to remember.”

James B. Maas and Rebecca S. Robbins, Sleep for Success, 2010

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 91

good, it can be self- administered, the supplies are limitless, and it’s free! If you are a typi- cal university - age student, often going to bed near 2:00 A.M. and dragged out of bed 6 hours later by the dreaded alarm, the treatment is simple: Each night just add an hour to your sleep.

2800

2700

2600

2500

2400 Spring time change (hour of sleep lost)

Monday before time change

Number of accidents

4200

4000

3800

3600 Fall time change

(hour of sleep gained)

Monday after time change

Less sleep, more accidents

More sleep, fewer accidents

Number of accidents

Heart Increased risk of high blood pressure

Stomach Increased hunger-arousing ghrelin and decreased hunger-suppressing leptin

Muscles Reduced strength; slower reaction time and motor learning

Joints Increased inflammation and arthritis

Fat cells Increased production; greater risk of obesity

Immune system Suppression of immune cell production and increased risk of viral infections, such as colds

Brain Diminished attentional focus and memory consolidation; increased risk of depression

FIGURE 3.12

Canadian traffic accidents On the Monday after the spring time change, when people lose one hour of sleep, accidents increased, as compared with the Monday before. In the fall, traffic accidents normally increase because of greater snow, ice, and darkness, but they diminished after the time change. (Adapted from Coren, 1996.)

FIGURE 3.13

How sleep deprivation affects us

Major Sleep Disorders No matter what their normal need for sleep, 1 in 10 adults, and 1 in 4 older adults, com- plain of insomnia—not an occasional inability to sleep when anxious or excited, but persistent problems in falling or staying asleep (Irwin et al., 2006). Ma

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From middle age on, awakening occasionally during the night becomes the norm, not something to fret over or treat with medication (Vitiello, 2009). Ironically, insomnia is worsened by fretting about one’s insomnia. In laboratory studies, insomnia complain- ers do sleep less than others, but they typically overestimate—by about double—how long it takes them to fall asleep. They also underestimate by nearly half how long they actually have slept. Even if we have been awake only an hour or two, we may think we have had very little sleep because it’s the waking part we remember.

The most common quick fixes for true insomnia—sleeping pills and alcohol—can aggravate the problem, reducing REM sleep and leaving the person with next - day blahs. Such aids can also lead to tolerance—a state in which increasing doses are needed to pro- duce an effect. An ideal sleep aid would mimic the natural chemicals abundant during sleep, reliably producing sound sleep without side effects. Until scientists can supply this magic pill, sleep experts have offered some tips for getting better quality sleep (TABLE 3.1).

Falling asleep is not the problem for people with narcolepsy (from narco, “numb- ness,” and lepsy, “seizure”), who have sudden attacks of overwhelming sleepiness, usually lasting less than 5 minutes. Narcolepsy attacks can occur at the most inopportune times, perhaps just after taking a terrific swing at a softball or when laughing loudly, shout- ing angrily, or having sex (Dement, 1978, 1999). In severe cases, the person collapses directly into a brief period of REM sleep, with loss of muscular tension. People with narcolepsy—1 in 2000 of us, estimated the Stanford University Center for Narcolepsy (2002)—must therefore live with extra caution. As a traffic menace, “snoozing is second only to boozing,” says the American Sleep Disorders Association, and those with narco- lepsy are especially at risk (Aldrich, 1989).

Although 1 in 20 of us have sleep apnea, it was unknown before modern sleep research. Apnea means “with no breath,” and people with this condition intermittently stop breathing during sleep. After an airless minute or so, decreased blood oxygen arouses them and they wake up enough to snort in air for a few seconds, in a process that repeats hundreds of times each night, depriving them of slow - wave sleep. Apnea sufferers don’t recall these episodes the next day. So, despite feeling fatigued and depressed—and hear- ing their mate’s complaints about their loud “snoring”—many are unaware of their disorder (Peppard et al., 2006).

Sleep apnea is associated with obesity, and as the number of obese Americans has increased, so has sleep apnea, particularly among overweight men, including some foot- ball players (Keller, 2007). In addition to loud snoring, other warning signs are daytime sleepiness, irritability, and (possibly) high blood pressure, which increases the risk of a stroke or heart attack (Dement, 1999). If one doesn’t mind looking a little goofy in the

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Economic recession and stress can rob sleep A National Sleep Foundation (2009) survey found 27 percent of people reporting sleeplessness related to the economy, their personal finances, and employment, as seems evident in this man looking for work.

Did Brahms need his own lullabies? Cranky, overweight, and nap-prone, classical composer Johannes Brahms exhibited common symptoms of sleep apnea (Margolis, 2000). The Granger Collection, New York

Table 3.1

Some Natural Sleep Aids

• Exercise regularly but not in the late evening. (Late afternoon is best.)

• Avoid caffeine after early afternoon, and avoid food and drink near bedtime. The exception would be a glass of milk, which provides raw materials for the manufacture of serotonin, a neurotransmitter that facilitates sleep.

• Relax before bedtime, using dimmer light.

• Sleep on a regular schedule (rise at the same time even after a restless night) and avoid naps.

• Hide the clock face so you aren’t tempted to check it repeatedly.

• Reassure yourself that temporary sleep loss causes no great harm.

• Realize that for any stressed organism, being vigilant is natural and adaptive. A personal conflict during the day often means a fitful sleep that night (Åkerstedt et al., 2007; Brissette & Cohen, 2002). Manag- ing your stress levels will enable more restful sleeping. (See Chapter 11 for more on stress.)

• If all else fails, settle for less sleep, either going to bed later or getting up earlier.

“The lion and the lamb shall lie down together, but the lamb will not be very sleepy.”

Woody Allen, in the movie Love and Death, 1975

“Sleep is like love or happiness. If you pursue it too ardently it will elude you.”

Wilse Webb, Sleep: The Gentle Tyrant, 1992

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 93

dark, the treatment —a masklike device with an air pump that keeps the sleeper’s airway open (imagine a snorkeler at a slumber party)—can effectively relieve apnea symptoms.

Unlike sleep apnea, night terrors target mostly children, who may sit up or walk around, talk incoherently, experience doubled heart and breathing rates, and appear ter- rified (Hartmann, 1981). They seldom wake up fully during an episode and recall little or nothing the next morning—at most, a fleeting, frightening image. Night terrors are not nightmares (which, like other dreams, typically occur during early morning REM sleep); night terrors usually occur during the first few hours of NREM-3.

Sleepwalking—another NREM-3 sleep disorder—and sleeptalking are usually child- hood disorders and, like narcolepsy, they run in families. (Sleeptalking—usually garbled or nonsensical—can occur during any sleep stage [Mahowald & Ettinger, 1990].) Occasional childhood sleepwalking occurs for about one - third of those with a sleepwalking fraternal twin and half of those with a sleepwalking identical twin. The same is true for sleeptalk- ing (Hublin et al., 1997, 1998). Sleepwalking is usually harmless. After returning to bed on their own or with the help of a family member, few sleepwalkers recall their trip the next morning. About 20 percent of 3- to 12-year - olds have at least one episode of sleepwalking, usually lasting 2 to 10 minutes; some 5 percent have repeated episodes (Giles et al., 1994). Young children, who have the deepest and lengthiest NREM-3 sleep, are the most likely to experience both night terrors and sleepwalking. As we grow older and deep NREM-3 sleep diminishes, so do night terrors and sleepwalking. After being sleep deprived, we sleep more deeply, which increases any tendency to sleepwalk (Zadra et al., 2008).

Dreams Now playing at an inner theater near you: the premiere showing of a sleeping person’s vivid dream. This never - before - seen mental movie features captivat- ing characters wrapped in a plot so original and unlikely, yet so intricate and so seemingly real, that the viewer later marvels at its creativity.

Waking from a troubling dream, wrenched by its emotions, who among us has not wondered about this weird state of consciousness? How can our brain so creatively, colorfully, and completely construct this alternative world? In the shadowland between our dreaming and waking consciousness, we may even wonder for a moment which is real.

Discovering the link between REM sleep and dreaming opened a new era in dream research. Instead of relying on someone’s hazy recall hours or days after having a dream, researchers could catch dreams as they happened. They could awaken people during or within 3 minutes after a REM sleep period and hear a vivid account.

What We Dream

3-9: What do we dream?

Daydreams tend to involve the familiar details of our life—perhaps picturing ourselves explaining to an instructor why a paper will be late, or replaying in

our minds personal encounters we relish or regret. REM dreams—“hallucinations of the sleeping mind”(Loftus & Ketcham, 1994, p. 67)—are vivid, emotional, and bizarre— so vivid we may confuse them with reality. Awakening from a nightmare, a 4-year - old may be sure there is a bear in the house.

We spend 6 years of our life in dreams, many of which are anything but sweet. For both women and men, 8 in 10 dreams are marked by at least one negative event or emotion (Domhoff, 2007). Common themes are repeatedly failing in an attempt to do something; being attacked, pursued, or rejected; or experiencing misfortune (Hall et al., 1982). Dreams with sexual imagery occur less often than you might think. In one study, only 1 in 10 dreams among young men and 1 in 30 among young women had sexual content (Domhoff, 1996). More commonly, a dream’s story line incorporates traces of previous days’ nonsexual experiences and preoccupations (De Koninck, 2000):

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A dreamy take on dreamland The 2010 movie Inception creatively plays off our interest in finding meaning in our dreams and in understanding the layers of our consciousness. It further explores the idea of creating false memories through the power of suggestion—an idea we will explore in Chapter 8.

narcolepsy a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.

sleep apnea a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.

night terrors a sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 sleep, within two or three hours of falling asleep, and are seldom remembered.

dream a sequence of images, emotions, and thoughts passing through a sleeping person’s mind. Dreams are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the dreamer’s delusional acceptance of the content and later difficulties remembering it.

Would you suppose that people dream if blind from birth? Studies in France, Hungary, Egypt, and the United States all found blind people dreaming of using their nonvisual senses—hearing, touching, smelling, tasting (Buquet, 1988; Taha, 1972; Vekassy, 1977).

“I do not believe that I am now dreaming, but I cannot prove that I am not.”

Philosopher Bertrand Russell (1872–1970)

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• After suffering a trauma, people commonly report nightmares, which help extin- guish daytime fears (Levin & Nielsen, 2007, 2009). One sample of Americans recording their dreams during September 2001 reported an increase in threatening dreams following the 9/11 attacks (Propper et al., 2007).

• After playing the computer game Tetris for 7 hours and then being awakened repeatedly during their first hour of sleep, 3 in 4 people reported experiencing images of the game’s falling blocks (Stickgold et al., 2000).

• Compared with city dwellers, people in hunter - gatherer societies more often dream of animals (Mestel, 1997). Compared with nonmusicians, musicians report twice as many dreams of music (Uga et al., 2006).

Our two-track mind continues to monitor our environment while we sleep. Sen- sory stimuli—a particular odor or a phone’s ringing—may be instantly and ingeniously woven into the dream story. In a classic experiment, researchers lightly sprayed cold water on dreamers’ faces (Dement & Wolpert, 1958). Compared with sleepers who did not get the cold - water treatment, these people were more likely to dream about a water- fall, a leaky roof, or even about being sprayed by someone.

So, could we learn a foreign language by hearing it played while we sleep? If only it were so easy. While sleeping, we can learn to associate a sound with a mild electric shock (and to react to the sound accordingly). But we do not remember recorded information played while we are soundly asleep (Eich, 1990; Wyatt & Bootzin, 1994). In fact, anything that happens during the 5 minutes just before we fall asleep is typically lost from memory (Roth et al., 1988). This explains why sleep apnea patients, who repeatedly awaken with a gasp and then immediately fall back to sleep, do not recall the episodes. It also explains why dreams that momentarily awaken us are mostly forgotten by morning. To remember a dream, get up and stay awake for a few minutes.

Why We Dream

3-10: What are the functions of dreams?

Dream theorists have proposed several explanations of why we dream, includ- ing these five:

To satisfy our own wishes. In 1900, in his landmark book The Interpretation of Dreams, Sigmund Freud offered what he thought was “the most valuable of all the discoveries it has been my good fortune to make.” He proposed that dreams provide a psychic safety valve that discharges otherwise unacceptable feelings. He viewed a dream’s manifest

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“For what one has dwelt on by day, these things are seen in visions of the night.”

Menander of Athens (342–292 B.C.E.), Fragments

A popular sleep myth: If you dream you are falling and hit the ground (or if you dream of dying), you die. (Unfortunately, those who could confirm these ideas are not around to do so. Some people, how ever, have had such dreams and are alive to report them.)

“Follow your dreams, except for that one where you’re naked at work.”

Attributed to Henny Youngman

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content (the apparent and remembered story line) as a censored, symbolic version of its latent content, the unconscious drives and wishes that would be threatening if expressed directly. Although most dreams have no overt sexual imagery, Freud neverthe- less believed that most adult dreams could be “traced back by analysis to erotic wishes.” Thus, a gun might be a disguised representation of a penis.

Freud considered dreams the key to understanding our inner conflicts. However, his critics say it is time to wake up from Freud’s dream theory, which is a scientific night- mare. Based on the accumulated science, “there is no reason to believe any of Freud’s specific claims about dreams and their purposes,” observed dream researcher William Domhoff (2003). Some contend that even if dreams are symbolic, they could be inter- preted any way one wished. Others maintain that dreams hide nothing. A dream about a gun is a dream about a gun. Legend has it that even Freud, who loved to smoke cigars, acknowledged that “sometimes, a cigar is just a cigar.” Freud’s wish - fulfillment theory of dreams has in large part given way to other theories.

To file away memories. The information-processing perspective proposes that dreams may help sift, sort, and fix the day’s experiences in our memory. Some studies support this view. When tested the day after learning a task, those who had been deprived of both slow -wave and REM sleep did not do as well as those who had slept undis- turbed on their new learning (Stickgold et al., 2000, 2001). In other studies, people who heard unusual phrases or learned to find hidden visual images before bedtime remembered less the next morning if they had been awakened every time they began REM sleep than if awakened during other sleep stages (Empson & Clarke, 1970; Karni & Sagi, 1994).

Brain scans confirm the link between REM sleep and memory. The brain regions that buzzed as rats learned to navigate a maze, or as people learned to perform a visual- discrimination task, buzzed again during later REM sleep (Louie & Wilson, 2001; Maquet, 2001). So precise were these activity patterns that scientists could tell where in the maze the rat would be if awake. Some, however, are unpersuaded by these studies, noting that memory consolidation may also occur during non-REM sleep (Siegel, 2001; Vertes & Siegel, 2005). This much seems true: A night of solid sleep (and dreaming) has an important place in our lives. To sleep, perchance to remember.

This is important news for students, many of whom, observed researcher Robert Stickgold (2000), suffer from a kind of sleep bulimia—binge sleeping on the weekend. “If you don’t get good sleep and enough sleep after you learn new stuff, you won’t integrate it effectively into your memories,” he warned. That helps explain why sec- ondary students with high grades have averaged 25 minutes more sleep a night than their lower-achieving classmates (Wolfson & Carskadon, 1998).

To develop and preserve neural pathways. Perhaps dreams, or the brain activity associ- ated with REM sleep, serve a physiological function, providing the sleeping brain with periodic stimulation. This theory makes developmental sense. As you will see in Chap- ter 4, stimulating experiences preserve and expand the brain’s neural pathways.

To make sense of neural static. Other theories propose that dreams erupt from neural activation spreading upward from the brainstem (Antrobus, 1991; Hobson, 2003, 2004, 2009). According to one version, dreams are the brain’s attempt to make sense of random neural activity. Much as a neurosurgeon can produce hallucinations by stimulating dif- ferent parts of a patient’s cortex, so can stimulation originating within the brain. These internal stimuli activate brain areas that process visual images, but not the visual cortex area, which receives raw input from the eyes. As Freud might have expected, PET scans of sleeping people also reveal increased activity in the emotion - related limbic system (in the amygdala) during REM sleep. In contrast, frontal lobe regions responsible for inhibition and logical thinking seem to idle, which may explain why our dreams are less inhibited than we are when awake (Maquet et al., 1996). Add the limbic system’s emotional tone to the brain’s visual bursts and—Voila!—we dream. Damage either the limbic system or the visual centers active during dreaming, and dreaming itself may be impaired (Domhoff, 2003).

manifest content according to Freud, the remembered story line of a dream (as distinct from its latent, or hidden, content).

latent content according to Freud, the underlying meaning of a dream (as distinct from its manifest content).

“When people interpret [a dream] as if it were meaningful and then sell those interpretations, it’s quackery.”

Sleep researcher J. Allan Hobson (1995)

Rapid eye movements also stir the liquid behind the cornea; this delivers fresh oxygen to corneal cells, preventing their suffocation.

Question: Does eating spicy foods cause one to dream more? Answer: Any food that causes you to awaken more increases your chance of recalling a dream (Moorcroft, 2003).

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Table 3.2

Dream Theories

Theory Explanation Critical Considerations

Freud’s wish - fulfillment Dreams provide a “psychic safety valve”—expressing otherwise unacceptable feelings; contain manifest (remembered) content and a deeper layer of latent content (a hidden meaning).

Lacks any scientific support; dreams may be inter- preted in many different ways.

Information - processing Dreams help us sort out the day’s events and consolidate our memories.

But why do we sometimes dream about things we have not experienced?

Physiological function Regular brain stimulation from REM sleep may help develop and preserve neural pathways.

This does not explain why we experience meaning- ful dreams.

Neural activation REM sleep triggers neural activity that evokes random visual memories, which our sleeping brain weaves into stories.

The individual’s brain is weaving the stories, which still tells us something about the dreamer.

Cognitive development Dream content reflects dreamers’ cognitive development—their knowledge and understanding.

Does not address the neuroscience of dreams.

To reflect cognitive development. Some dream researchers dispute both the Freudian and neural activation theories, preferring instead to see dreams as part of brain matura- tion and cognitive development (Domhoff, 2010, 2011; Foulkes, 1999). For example, prior to age 9, children’s dreams seem more like a slide show and less like an active story in which the dreamer is an actor. Dreams overlap with waking cognition and feature coherent speech. They simulate reality by drawing on our concepts and knowledge. They engage brain networks that also are active during daydreaming. Unlike the idea that dreams arise from bottom-up brain activation, the cognitive perspective emphasizes our mind’s top-down control of our dream content (Nir & Tononi, 2010).

TABLE 3.2 compares these major dream theories. Although sleep researchers debate dreams’ functions—and some are skeptical that dreams serve any function— there is one thing they agree on: We need REM sleep. Deprived of it by repeatedly being awakened, people return more and more quickly to the REM stage after fall- ing back to sleep. When finally allowed to sleep undisturbed, they literally sleep like babies—with increased REM sleep, a phenomenon called REM rebound. With- drawing REM-suppressing sleeping medications also increases REM sleep, but with accompanying nightmares.

Most other mammals also experience REM rebound, suggesting that the causes and functions of REM sleep are deeply biological. That REM sleep occurs in mammals— and not in animals such as fish, whose behavior is less influenced by learning—also fits the information - processing theory of dreams.

So does this mean that because dreams serve physiological functions and extend normal cognition, they are psychologically meaningless? Not necessarily. Every psycho- logically meaningful experience involves an active brain. We are once again reminded of a basic principle: Biological and psychological explanations of behavior are partners, not competitors.

Dreams are a fascinating altered state of consciousness. But they are not the only altered states. Hypnosis and drugs also alter conscious awareness.

RETRIEVE IT

• What five theories explain why we dream?

ANSWER: (1) Freud’s wish-fulfillment (dreams as a psychic safety valve), (2) information-processing (dreams sort the day’s events and form memories), (3) physiological function (dreams pave neural pathways), (4) neural activation (REM sleep triggers random neural activity that the mind weaves into stories), (5) cognitive development (dreams reflect the dreamer’s developmental stage)

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Hypnosis 3-11: What is hypnosis, and what powers does a hypnotist have over a hypnotized subject?

Imagine you are about to be hypnotized. The hypnotist invites you to sit back, fix your gaze on a spot high on the wall, and relax. In a quiet voice the hypnotist suggests, “Your eyes are growing tired. . . . Your eyelids are becoming heavy . . . now heavier and heavier. . . . They are beginning to close. . . . You are becoming more deeply relaxed. . . . Your breathing is now deep and regular. . . . Your muscles are becoming more and more relaxed. Your whole body is beginning to feel like lead.”

After a few minutes of this hypnotic induction, you may experience hypnosis. When the hypnotist suggests, “Your eyelids are shutting so tight that you cannot open them even if you try,” it may indeed seem beyond your control to open your eyelids. Told to forget the number 6, you may be puzzled when you count 11 fingers on your hands. Invited to smell a sensuous perfume that is actually ammonia, you may linger delightedly over its pungent odor. Told that you cannot see a certain object, such as a chair, you may indeed report that it is not there, although you manage to avoid the chair when walking around (illustrating the dual processing talents of that mind of yours).

But is hypnosis really an altered state of consciousness? Let’s start with some frequently asked questions.

Frequently Asked Questions About Hypnosis Hypnotists have no magical mind - control power. Their power resides in the subjects’ openness to suggestion and ability to focus (Bowers, 1984). But how open to sugges- tions are we?

• Can anyone experience hypnosis? To some extent, we are all open to suggestion. When people stand upright with their eyes closed and are told that they are sway- ing back and forth, most will indeed sway a little. In fact, postural sway is one of the items assessed on the Stanford Hypnotic Susceptibility Scale. People who respond to such suggestions without hypnosis are the same people who respond with hyp- nosis (Kirsch & Braffman, 2001).

Highly hypnotizable people—say, the 20 percent who can carry out a suggestion not to smell or react to a bottle of ammonia held under their nose—typically become deeply absorbed in imaginative activities (Barnier & McConkey, 2004; Silva & Kirsch, 1992). Many researchers refer to this as hypnotic ability—the ability to focus attention totally on a task, to become imaginatively absorbed in it, to entertain fanciful possibilities.

• Can hypnosis enhance recall of forgotten events? Most people believe (wrongly, as Chapter 8 will explain) that our experiences are all “in there,” recorded in our brain and available for recall if only we can break through our own defenses (Loftus, 1980). But 60 years of memory research disputes such beliefs. We do not encode everything that occurs around us. We permanently store only some of our experi- ences, and we may be unable to retrieve some memories we have stored.

“Hypnotically refreshed” memories combine fact with fiction. Since 1980, thou- sands of people have reported being abducted by UFOs, but most such reports have come from people who are predisposed to believe in aliens, are highly hypnotizable, and have undergone hypnosis (Newman & Baumeister, 1996; Nickell, 1996). With- out either person being aware of what is going on, a hypnotist’s hints—“Did you hear loud noises?”—can plant ideas that become the subject’s pseudomemory.

So should testimony obtained under hypnosis be admissable in court? American, Australian, and British courts have agreed it should not. They generally ban testimony from witnesses who have been hypnotized (Druckman & Bjork, 1994; Gibson, 1995; McConkey, 1995).

REM rebound the tendency for REM sleep to increase following REM sleep deprivation (cre- ated by repeated awakenings during REM sleep).

hypnosis a social interaction in which one person (the hypnotist) suggests to another (the subject) that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur.

“Hypnosis is not a psychological truth serum and to regard it as such has been a source of considerable mischief.”

Researcher Kenneth Bowers (1987)

See Chapter 8 for a more detailed discussion of how people may construct false memories.

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98 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND o4

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• Can hypnosis force people to act against their will? Researchers have induced hyp- notized people to perform an apparently dangerous act: plunging one hand briefly into fuming “acid,” then throwing the “acid” in a researcher’s face (Orne & Evans, 1965). Interviewed a day later, these people emphatically denied their acts and said they would never follow such orders.

Had hypnosis given the hypnotist a special power to control others against their will? To find out, researchers Martin Orne and Frederich Evans unleashed that enemy of so many illusory beliefs—the control group. Orne asked other individu- als to pretend they were hypnotized. Laboratory assistants, unaware that those in the experiment’s control group had not been hypnotized, treated both groups the same. The result? All the unhypnotized participants (perhaps believing that the laboratory context assured safety) performed the same acts as those who were hypnotized.

• Can hypnosis help people heal or relieve their pain? Hypnotherapists try to help patients harness their own healing powers (Baker, 1987). Posthypnotic sugges- tions have helped alleviate headaches, asthma, and stress - related skin disorders.

In one statistical digest of 18 studies, the average client whose therapy was supple- mented with hypnosis showed greater improvement than 70 percent of other therapy

patients (Kirsch et al., 1995, 1996). Hypnosis seemed especially helpful for the treatment of obesity. However, drug, alcohol, and smoking addictions have not responded well to hypnosis (Nash, 2001). In controlled studies, hypnosis did speed the disappearance of warts, but so did the same positive suggestions given without hypnosis (Spanos, 1991, 1996).

Hypnosis can relieve pain (Druckman & Bjork, 1994; Jensen, 2008). When unhypnotized people put their arm in an ice bath, they felt intense pain within 25 seconds. When hypnotized people did the same after being given suggestions to feel no pain, they indeed reported feeling little pain. As some dentists know, light hypnosis can reduce fear, thus reducing hypersensitivity to pain.

Hypnosis inhibits pain-related brain activity. In surgical experi- ments, hypnotized patients have required less medication, recov- ered sooner, and left the hospital earlier than unhypnotized control patients (Askay & Patterson, 2007; Hammond, 2008; Spiegel, 2007). Nearly 10 percent of us can become so deeply hypnotized that even major surgery can be performed without anesthesia. Half of us can gain at least some pain relief from hypnosis. The surgical use

of hypnosis has flourished in Europe, where one Belgian medical team has performed more than 5000 surgeries with a combination of hypnosis, local anesthesia, and a mild sedative (Song, 2006).

RETRIEVE IT

• When is the use of hypnosis potentially harmful, and when can hypnosis be used to help?

ANSWER: Hypnosis can be harmful if used to “hypnotically refresh” memories, which may plant false memories. But posthypnotic suggestions have helped alleviate some ailments, and hypnosis can also help control pain.

Explaining the Hypnotized State

3-12: Is hypnosis an extension of normal consciousness or an altered state?

We have seen that hypnosis involves heightened suggestibility. We have also seen that hypnotic procedures do not endow a person with special powers but can sometimes help people overcome stress-related ailments and cope with pain. So, just what is hypnosis? Psychologists have proposed two explanations.

Stage hypnotist

posthypnotic suggestion a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control unde- sired symptoms and behaviors.

“It wasn’t what I expected. But facts are facts, and if one is proved to be wrong, one must just be humble about it and start again.”

Agatha Christie’s Miss Marple

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 99

Hypnosis as a Social Phenomenon Our attentional spotlight and interpretations powerfully influence our ordinary percep- tions. Might hypnotic phenomena reflect such workings of normal consciousness, as well as the power of social influence (Lynn et al., 1990; Spanos & Coe, 1992)? Advocates of the social influence theory of hypnosis believe they do.

Does this mean that subjects consciously fake hypnosis? No—like actors caught up in their roles, they begin to feel and behave in ways appropriate for “good hypnotic subjects.” The more they like and trust the hypnotist, the more they allow that person to direct their attention and fantasies (Gfeller et al., 1987). “The hypnotist’s ideas become the subject’s thoughts,” explained Theodore Barber (2000), “and the subject’s thoughts produce the hypnotic experiences and behaviors.” Told to scratch their ear later when they hear the word psychology, subjects will likely do so—but only if they think the experiment is still under way. If an experimenter eliminates their motivation for acting hypnotized—by stating that hypnosis reveals their “gullibility”—subjects become unre- sponsive. Such findings support the idea that hypnotic phenomena are an extension of normal social and cognitive processes.

These views illustrate a principle that Chapter 13 emphasizes: An authoritative person in a legitimate context can induce people—hypnotized or not—to perform some unlikely acts. Or as hypnosis researcher Nicholas Spanos (1982) put it, “The overt behaviors of hypnotic subjects are well within normal limits.”

Hypnosis as Divided Consciousness Other hypnosis researchers believe hypnosis is more than inducing someone to play the role of “good subject.” How, they ask, can we explain why hypnotized subjects some- times carry out suggested behaviors on cue, even when they believe no one is watching (Perugini et al., 1998)? And why does distinctive brain activity accompany hypnosis (Oakley & Halligan, 2009)? In one experiment, deeply hypnotized people were asked to imagine a color, and areas of their brain activated as if they were really seeing the color. To the hypnotized person’s brain, mere imagination had become a compelling halluci- nation (Kosslyn et al., 2000).

These results would not have surprised famed researcher Ernest Hilgard (1986, 1992), who believed hypnosis involves not only social influence but also a special dual- processing state of dissociation—a split between different levels of consciousness. Hilgard viewed hypnotic dissociation as a vivid form of everyday mind splits—similar to doodling while listening to a lecture or typing the end of a sentence while starting a conversation. For example, Hilgard felt that when hypnotized people lower their arm into an ice bath, as in FIGURE 3.14, the hypnosis dissociates the sensation of the pain stimulus (of which the subjects are still aware) from the emotional suffering that defines their experience of pain. The ice water therefore feels cold—very cold—but not painful.

Divided-consciousness theory:

Hypnosis has caused a split in awareness.

Attention is diverted from a painful ice bath. How?

Social influence theory:

The subject is so caught up in the hypnotized role that she ignores the cold.

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dissociation a split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others.

FIGURE 3.14

Dissociation or role-playing? This hypnotized woman tested by Ernest Hilgard exhibited no pain when her arm was placed in an ice bath. But asked to press a key if some part of her felt the pain, she did so. To Hilgard, this was evidence of dissociation, or divided consciousness. Proponents of social influence theory, however, maintain that people responding this way are caught up in playing the role of “good subject.”

“The total possible consciousness may be split into parts which co - exist but mutually ignore each other.”

William James, Principles of Psychology, 1890

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100 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Another form of dual processing—selective attention—may also play a role in hypnotic pain relief. PET scans show that hypnosis reduces brain activity in a region that processes pain- ful stimuli, but not in the sensory cortex, which receives the raw sensory input (Rainville et al., 1997). Hypnosis does not block sensory input, but it may block our attention to those stimuli. This helps explain why an injured athlete, caught up in the competition, may feel little or no pain until the game ends.

Although the divided - consciousness theory of hypnosis is controversial, this much seems clear: There is, without doubt, much more to thinking and acting than we are conscious of. Our information processing, which starts with selective attention, is divided into simultaneous conscious and nonconscious realms. In hypnosis as in life, much of our behavior occurs on autopilot. We have two-track minds (FIGURE 3.15).

* * * There is controversy about whether hypnosis uniquely alters consciousness, but there is little dispute that some drugs do.

RETRIEVE IT

• Hilgard believed that hypnosis involves a state of divided consciousness called

. His beliefs have been challenged by researchers who suggest

influence is involved.

ANSWERS: dissociation; social

Drugs and Consciousness Let’s imagine a day in the life of a legal - drug user. It begins with a wake - up latte. By midday, several cigarettes have calmed frazzled nerves before an appointment at the plastic surgeon’s office for wrinkle-smoothing Botox injections. A diet pill before din- ner helps stem the appetite, and its stimulating effects can later be partially offset with a glass of wine and two Tylenol PMs. And if performance needs enhancing, there are beta blockers for onstage performers, Viagra for middle - aged men, hormone-delivering “libido patches” for middle - aged women, and Adderall for students hoping to focus their concentration. Before drifting off into REM-depressed sleep, our hypothetical drug user is dismayed by news reports of pill-sharing, pill-popping college students.

Most of us manage to use some nonprescription drugs in moderation and without disrupting our lives. But some of us develop self-harming substance-related disorders. In such cases, the substances being used are psychoactive drugs, chemicals that change perceptions and moods. A drug’s overall effect depends not only on its biological effects but also on the psychology of the user’s expectations, which vary with social and cultural contexts (Ward, 1994). If one culture assumes that a particular drug produces euphoria (or aggression or sexual arousal) and another does not, each culture may find its expecta- tions fulfilled. In the pages that follow, we’ll take a closer look at these interacting forces in the use and potential abuse of particular psychoactive drugs. But first, let’s see how our bodies react to the ongoing use of psychoactive drugs.

Tolerance, Dependence, and Addiction

3-13: What are tolerance, dependence, and addiction, and what are some common misconceptions about addiction?

Why might a person who rarely drinks alcohol get buzzed on one can of beer while a long-term drinker shows few effects until the second six - pack? The answer is tolerance. With continued use of alcohol and some other drugs (mari- juana is an exception), the user’s brain chemistry adapts to offset the drug effect (a process called neuroadaptation). To experience the same effect, the user requires larger

Biological influences:

Social-cultural influences:

Hypnosis

Psychological influences:

psychoactive drug a chemical substance that alters perceptions and moods.

tolerance with repeated use, achieving the desired effect requires larger doses.

addiction compulsive drug craving and use, despite adverse consequences.

FIGURE 3.15

Levels of analysis for hypnosis Using a bio psycho social approach, researchers explore hypnosis from complementary perspectives.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 101

Addiction

In recent pop psychology, the supposedly irresistible seduction of addiction has been extended to cover many behaviors formerly considered bad habits or even sins. Has the concept been stretched too far? Are addictions as irresistible as commonly believed? Let’s consider three big questions.

1. Do addictive drugs quickly corrupt? For example, does morphine taken to control pain often lead to heroin abuse? Generally not. People given morphine for pain control rarely develop the cravings of the addict who uses morphine as a mood - altering drug (Melzack, 1990). Some—perhaps 10 percent—do indeed have a hard time using a psychoactive drug in moderation or stop- ping altogether. But controlled, occasional users of drugs such as alcohol and mari- juana far outnumber those who become addicted to these substances (Gazzaniga, 1988; Siegel, 1990). “Even for a very addictive drug like cocaine, only 15 to 16 percent of people become addicted within 10 years of first use,” observed Terry Rob- inson and Kent Berridge (2003).

2. Does overcoming an addiction require therapy? Addictions can be powerful, and some addicts do benefit from therapy or group support. Alcoholics Anonymous has supported many people in overcoming their alcohol dependence. But the recovery rates of treated and untreated groups differ less than one might suppose. Moreover, viewing addiction as an uncontrollable disease can

undermine people’s self - confidence and their belief that they can change. And that, critics say, would be unfortunate, for many peo- ple do voluntarily stop using addictive drugs, without any treatment. Most of America’s 41 million ex-smokers kicked the habit on their own, usu- ally after prior failed efforts or treatments.

3. Can we extend the concept of addiction to cover not just drug dependencies, but a whole spectrum of repetitive, pleasure - seeking behaviors? We can, and we have, but should we? The addiction- as - disease-needing - treatment idea has been suggested for a host of driven, excessive behaviors—eating, shopping, gambling, work, and sex. Used not as a metaphor (“I’m a science fiction addict”) but as real- ity, “addiction” can become an all - purpose excuse. Moreover, labeling a behavior doesn’t explain it. Attributing serial adul- tery, as in the case of Tiger Woods, to a “sex addiction” does not explain the sexual impulsiveness, say critics (Radford, 2010).

Sometimes, though, behaviors such as gam- bling, video gaming, or online surfing do become compulsive and dysfunctional, much like abu- sive drug taking (Gentile, 2009; Griffiths, 2001;

Hoeft et al., 2008). Some Internet users, for example, do display an apparent inability to resist logging on, and staying on, even when this excessive use impairs their work and rela- tionships (Ko et al., 2005). Are we justified in stretching the addiction concept to cover such social behaviors? Stay tuned. Debates over the addiction - as- disease model continue.

THINKING CRITICALLY ABOUT:

A social networking addiction?

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The odds of getting hooked after using various drugs: Tobacco 32% Heroin 23% Alcohol 15% Marijuana 9%

Source: National Academy of Science, Institute of Medicine (Brody, 2003).

and larger doses (FIGURE 3.16). In chronic alcohol abuse, for example, the person’s brain, heart, and liver suffer damage from the excessive amounts of alcohol being “tol- erated.” Ever-increasing doses of most psychoactive drugs can pose a serious threat to health and may lead to addiction: The person craves and uses the substance despite its adverse consequences. (See Thinking Critically About: Addiction.) The World Health Organization (2008) has reported that, worldwide, 90 million people suffer from such problems related to alcohol and other drugs.

RETRIEVE IT

• What is the process that leads to drug tolerance?

ANSWER: With repeated exposure to a psychoactive drug, the drug’s effect lessens. Thus, it takes bigger doses to get the desired effect.

Drug effect

Drug dose

Response to first exposure

After repeated exposure, more drug is needed to produce same effect

Small Large

Little effect

Big effect

Dru

FIGURE 3.16

Drug tolerance

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102 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Regular users often try to fight their addiction, but abruptly stopping the drug may lead to the undesirable side effects of withdrawal. As the body responds to the drug’s absence, the user may feel physical pain and intense cravings, indicating physi- cal dependence. People can also develop psychological dependence, particularly for stress-relieving drugs, such as alcohol. Although not always physically addictive, such drugs may nevertheless become an important part of the user’s life, often as a way of relieving negative emotions. For someone who is either physically or psychologically dependent, obtaining and using the drug can become the day’s focus.

Types of Psychoactive Drugs The three major categories of psychoactive drugs are depressants, stimulants, and hallucino- gens. All do their work at the brain’s synapses, stimulating, inhibiting, or mimicking the activity of the brain’s own chemical messengers, the neurotransmitters.

Depressants

3-14: What are depressants, and what are their effects?

Depressants are drugs such as alcohol, barbiturates (tranquilizers), and opiates that calm neural activity and slow body functions.

Alcohol True or false? In small amounts, alcohol is a stimulant. False. Low doses of alcohol may, indeed, enliven a drinker, but they do so by acting as a disinhibitor— they slow brain activity that controls judgment and inhibitions. Alcohol is an equal - opportunity drug: It increases (disinhibits) helpful tendencies, as when tipsy restaurant patrons leave extravagant tips (Lynn, 1988). And it increases harmful tendencies, as when sexually aroused men become more disposed to sexual aggression.

Alcohol + sex = the perfect storm. When drinking, both men and women are more disposed to casual sex (Cooper, 2006; Ebel-Lam et al., 2009). The urges you would feel if sober are the ones you will more likely act upon when intoxicated.

SLOWED NEURAL PROCESSING Low doses of alcohol relax the drinker by slowing sympathetic nervous system activity. Larger doses cause reactions to slow, speech to slur, and skilled performance to deteriorate. Paired with sleep deprivation, alcohol is a potent sedative. Add these physical effects to lowered inhibitions, and the result can be deadly. Worldwide, several hundred thousand lives are lost each year in alcohol - related accidents and violent crime. As blood - alcohol levels rise and judgment falters, people’s qualms about drinking and driving lessen. In experiments, virtually all drinkers who had insisted when sober that they would not drive under the influence later decided to drive home from a bar, even when given a breathalyzer test and told they were intoxicated (Denton & Krebs, 1990; MacDonald et al., 1995). Alcohol can also be life threatening when heavy drinking follows an earlier period of moderate drinking, which depresses the vomiting response. People may poison themselves with an overdose that their bodies would normally throw up.

MEMORY DISRUPTION Alcohol can disrupt memory formation, and heavy drink- ing can have long-term effects on the brain and cognition. In rats, at a developmental period corresponding to human adolescence, binge drinking contributes to nerve cell death and reduces the birth of new nerve cells. It also impairs the growth of synaptic connections (Crews et al., 2006, 2007). In humans, heavy drinking may lead to black- outs, in which drinkers are unable to recall people they met the night before or what they said or did while intoxicated. These blackouts result partly from the way alcohol suppresses REM sleep, which helps fix the day’s experiences into permanent memories.

The prolonged and excessive drinking that characterizes alcohol dependence can shrink the brain (FIGURE 3.17). Girls and young women (who have less of a stomach

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“That is not one of the seven habits of highly effective people.”

withdrawal the discomfort and distress that follow discontinuing the use of an addictive drug.

:physical dependence a physiological need for a drug, marked by unpleasant with- drawal symptoms when the drug is discontinued.

psychological dependence a psycho- logical need to use a drug, such as to relieve negative emotions.

depressants drugs (such as alcohol, barbi- turates, and opiates) that reduce neural activity and slow body functions.

alcohol dependence (popularly known as alcoholism). Alcohol use marked by toler- ance, withdrawal if suspended, and a drive to continue use.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 103

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enzyme that digests alcohol) can become addicted to alcohol more quickly than boys and young men do, and they are at risk for lung, brain, and liver damage at lower con- sumption levels (CASA, 2003; Wuethrich, 2001).

REDUCED SELF-AWARENESS AND SELF-CONTROL In one experiment, those who consumed alcohol (rather than a placebo beverage) were doubly likely to be caught mind-wandering during a reading task, yet were less likely to notice that they zoned out (Sayette et al., 2009). Alcohol not only reduces self-awareness, it also produces a sort of “myopia” by focusing attention on an arousing situation (such as a provocation) and distracting attention from normal inhibitions and future consequences (Giancola et al., 2010; Hull et al., 1986; Steele & Josephs, 1990).

Reduced self-awareness may help explain why people who want to suppress their awareness of failures or shortcomings are more likely to drink than are those who feel good about themselves. Losing a business deal, a game, or a romantic partner sometimes elicits a drinking binge.

EXPECTANCY EFFECTS As with other drugs, expectations influence behavior. When people believe that alcohol affects social behavior in certain ways, and believe, rightly or wrongly, that they have been drinking alcohol, they will behave accordingly (Moss & Albery, 2009). In a classic experiment, researchers gave Rutgers University men (who had volunteered for a study on “alcohol and sexual stimulation”) either an alcoholic or a nonalcoholic drink (Abrams & Wilson, 1983). (Both had strong tastes that masked any alcohol.) In each group, half the participants thought they were drinking alcohol and half thought they were not. After watching an erotic movie clip, the men who thought they had consumed alcohol were more likely to report having strong sexual fantasies and feeling guilt free. Being able to attribute their sexual responses to alcohol released their inhibitions—whether or not they had actually consumed any alcohol. Alcohol’s effect lies partly in that powerful sex organ, the mind.

Barbiturates Like alcohol, the barbiturate drugs, or tranquilizers, depress nervous system activity. Barbiturates such as Nembutal, Seconal, and Amytal are sometimes prescribed to induce sleep or reduce anxiety. In larger doses, they can impair memory and judgment. If combined with alcohol—as sometimes happens when people take a sleeping pill after an evening of heavy drinking—the total depressive effect on body functions can be lethal.

Opiates The opiates—opium and its derivatives, morphine and heroin—also depress neural functioning. Pupils constrict, breathing slows, and lethargy sets in as blissful pleasure replaces pain and anxiety. For this short - term pleasure, opiate users may pay a long- term price: a gnawing craving for another fix, a need for progressively larger doses (as tolerance develops), and the extreme discomfort of withdrawal. When repeatedly flooded with an artificial opiate, the brain eventually stops producing endorphins, its own opiates. If the artificial opiate is then withdrawn, the brain lacks the normal level of these painkilling neurotransmitters. Those who cannot or choose not to tolerate this state may pay an ultimate price—death by overdose.

Scan of woman with alcohol dependence

Scan of woman without alcohol dependence

barbiturates drugs that depress central nervous system activity, reducing anxiety but impairing memory and judgment.

opiates opium and its derivatives, such as morphine and heroin; they depress neural activ- ity, temporarily lessening pain and anxiety.

FIGURE 3.17

Alcohol dependence shrinks the brain

MRI scans show brain shrinkage in women with alcohol dependence (left) compared with women in a control group (right).

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104 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

RETRIEVE IT

• Alcohol, barbiturates, and opiates are all in a class of drugs called .

ANSWER: depressants

Stimulants

3-15: What are stimulants, and what are their effects?

A stimulant excites neural activity and speeds up body functions. Pupils dilate, heart and breathing rates

increase, and blood sugar levels rise, causing a drop in appetite. Energy and self - confidence also rise.

Stimulants include caffeine, nicotine, the amphetamines, cocaine, methamphetamine (“speed”), and Ecstasy. People use stimulants to feel alert, lose weight, or boost mood or athletic performance. Unfortunately, stimulants can be addictive, as you may know if you are one of the many who use caffeine daily in your coffee, tea, soda, or energy drinks. Cut off from your usual dose, you may crash into fatigue, headaches, irritability, and depres- sion (Silverman et al., 1992). A mild dose of caffeine typically lasts three or four hours, which—if taken in the evening—may be long enough to impair sleep.

Nicotine One of the most addictive stimulants is nicotine, found in cigarettes and other tobacco products. Imagine that cigarettes were harmless—except, once in every 25,000 packs, an occasional innocent - looking one is filled with dynamite instead of tobacco. Not such a bad risk of having your head blown off. But with 250 million packs a day consumed worldwide, we could expect more than 10,000 gruesome daily deaths (more than three times the 9/11 fatalities each and every day)—surely enough to have cigarettes banned everywhere.1

The lost lives from these dynamite - loaded cigarettes approximate those from today’s actual cigarettes. A teen - to - the - grave smoker has a 50 percent chance of dying from the habit, and each year, tobacco kills nearly 5.4 million of its 1.3 billion customers world- wide. (Imagine the outrage if terrorists took down an equivalent of 25 loaded jumbo jets today, let alone tomorrow and every day thereafter.) By 2030, annual deaths are expected to increase to 8 million. That means that 1 billion twenty-first-century people may be killed by tobacco (WHO, 2008). Eliminating smoking would increase life expectancy more than any other preventive measure.

Those addicted to nicotine find it very hard to quit because tobacco products are as powerfully and quickly addictive as heroin and cocaine. Attempts to quit even within the first weeks of smoking often fail (DiFranza, 2008). As with other addictions, smok- ers become dependent, and they develop tolerance. Quitting causes nicotine - withdrawal symptoms, including craving, insomnia, anxiety, irritability, and distractibility. Nicotine- deprived smokers trying to focus on a task experience a tripled rate of mind wandering (Sayette et al., 2010). When not craving a cigarette, they tend to underestimate the power of such cravings (Sayette et al., 2008).

All it takes to relieve this aversive state is a cigarette—a portable nicotine dispenser. Within 7 seconds, a rush of nicotine signals the central nervous system to release a flood of neurotransmitters (FIGURE 3.18). Epinephrine and norepinephrine diminish appe- tite and boost alertness and mental efficiency. Dopamine and opioids calm anxiety and reduce sensitivity to pain (Nowak, 1994; Scott et al., 2004).

Vasca/Shutterstock

1 This analogy, adapted here with world - based numbers, was suggested by mathematician Sam Saunders, as reported by K. C. Cole (1998).

Smoke a cigarette and nature will charge you 12 minutes—ironically, just about the length of time you spend smoking it (Discover, 1996).

Humorist Dave Barry (1995) recalling why he smoked his first cigarette the summer he turned 15: “Arguments against smoking: ‘It’s a repulsive addiction that slowly but surely turns you into a gasping, gray - skinned, tumor - ridden invalid, hacking up brownish gobs of toxic waste from your one remaining lung.’ Arguments for smoking: ‘Other teenagers are doing it.’ Case closed! Let’s light up!”

stimulants drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, Ecstasy, and methamphetamine) that excite neural activity and speed up body functions.

amphetamines drugs that stimulate neural activity, causing speeded - up body functions and associated energy and mood changes.

nicotine a stimulating and highly addictive psychoactive drug in tobacco.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 105

1. Arouses the brain to a state of increased alertness

2. Increases heart rate and blood pressure

3. At high levels, relaxes muscles and triggers the release of neurotransmitters that may reduce stress

4. Reduces circulation to extremities

5. Suppresses appetite for carbohydrates

n

FIGURE 3.18

Where there’s smoke . . . : The

physiological effects of nicotine Nicotine reaches the brain within 7 seconds, twice as fast as intravenous heroin. Within minutes, the amount in the blood soars.

These rewards keep people smoking, even among the 8 in 10 smokers who wish they could stop (Jones, 2007). Each year, fewer than 1 in 7 smokers who want to quit will be able to resist. Even those who know they are committing slow - motion suicide may be unable to stop (Saad, 2002). Asked “If you had to do it all over again, would you start smoking?” more than 85 percent of adult smokers have answered No (Slovic et al., 2002).

Nevertheless, repeated attempts seem to pay off. Half of all Americans who have ever smoked have quit, sometimes aided by a nicotine replacement drug and with encouragement from a telephone counselor or a support group. Success is equally likely whether smokers quit abruptly or gradually (Fiore et al., 2008; Lichtenstein et al., 2010; Lindson et al., 2010). For those who endure, the acute craving and withdrawal symp- toms gradually dissipate over the ensuing 6 months (Ward et al., 1997). After a year’s abstinence, only 10 percent will relapse in the next year (Hughes et al., 2010). These nonsmokers may live not only healthier but also happier lives. Smoking correlates with higher rates of depression, chronic disabilities, and divorce (Doherty & Doherty, 1998; Vita et al., 1998). Healthy living seems to add both years to life and life to years.

RETRIEVE IT

• Why do tobacco companies try so hard to get customers hooked as teens?

ANSWER: Nicotine is powerfully addictive, expensive, and deadly. Those who start paving the neural pathways when young may find it very hard to stop using nicotine. As a result, tobacco companies may have lifelong customers.

Cocaine The recipe for Coca- Cola originally included an extract of the coca plant, creating a cocaine tonic for tired elderly people. Between 1896 and 1905, Coke was indeed “the real thing.” But no longer. Cocaine is now snorted, injected, or smoked. It enters the bloodstream quickly, producing a rush of euphoria that depletes the brain’s supply of the neurotransmitters dopamine, serotonin, and norepinephrine (FIGURE

“Cocaine makes you a new man. And the first thing that new man wants is more cocaine.”

Comedian George Carlin (1937–2008)

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106 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

3.19). Within the hour, a crash of agitated depression follows as the drug’s effect wears off. Many regular cocaine users chasing this high become addicted. In the lab, cocaine- addicted monkeys have pressed levers more than 12,000 times to gain one cocaine injection (Siegel, 1990).

In situations that trigger aggression, ingesting cocaine may heighten reactions. Caged rats fight when given foot shocks, and they fight even more when given cocaine and foot shocks. Likewise, humans ingesting high doses of cocaine in laboratory experiments impose higher shock levels on a presumed opponent than do those receiving a placebo (Licata et al., 1993). Cocaine use may also lead to emotional disturbances, suspiciousness, convulsions, cardiac arrest, or respiratory failure.

In national surveys, 3 percent of U.S. high school seniors and 6 percent of British 18- to 24-year-olds reported having tried cocaine during the past year (ACMD, 2009; Johnston et al., 2011). Nearly half had smoked crack, a faster-working crystallized form of cocaine that produces a briefer but more intense high, followed by a more intense crash. After several hours, the craving for more wanes, only to return several days later (Gawin, 1991).

Cocaine’s psychological effects depend in part on the dosage and form consumed, but the situation and the user’s expectations and personality also play a role. Given a

placebo, cocaine users who thought they were taking cocaine often had a cocaine-like experience (Van Dyke & Byck, 1982).

Methamphetamine Methamphetamine is chemically related to its parent drug, amphetamine (NIDA, 2002, 2005) but has even greater effects. Methamphetamine triggers the release of the neurotransmitter dopamine, which stimulates brain cells that enhance energy and mood, leading to eight hours or so of heightened energy and euphoria. Its aftereffects may include irritability, insomnia, hypertension, seizures, social isolation, depression, and occasional violent outbursts (Homer et al., 2008). Over time, methamphet- amine may reduce baseline dopamine levels, leaving the user with depressed functioning.

Synaptic gap

Receptor sites

Receiving neuron

Neurotransmitter molecule

Action potential

Sending neuron

Reuptake

Cocaine

(c)(b)(a)

By binding to the sites that normally reabsorb neurotransmitter molecules, cocaine blocks reuptake of dopamine, norepinephrine, and serotonin (Ray & Ksir, 1990). The extra neurotransmitter molecules therefore remain in the synapse, intensifying their normal mood- altering effects and producing a euphoric rush. When the cocaine level drops, the absence of these neurotransmitters produces a crash.

Neurotransmitters carry a message from a sending neuron across a synapse to receptor sites on a receiving neuron.

The sending neuron normally reabsorbs excess neurotransmitter molecules, a process called reuptake.

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Dramatic drug-induced decline This woman’s methamphetamine addiction led to obvious physical changes. Her decline is evident in these two photos, taken at age 36 (left) and, after four years of addiction, at age 40 (right).

sites on a receiving neuron.

FIGURE 3.19

Cocaine euphoria and crash

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 107

Ecstasy Ecstasy, a street name for MDMA (methylenedioxymethamphet- amine), is both a stimulant and a mild hallucinogen. As an amphetamine derivative, Ecstasy triggers dopamine release, but its major effect is releasing stored serotonin and blocking its reuptake, thus prolonging serotonin’s feel - good flood (Braun, 2001). Users feel the effect about a half- hour after taking an Ecstasy pill. For three or four hours, they experience high energy, emotional elevation, and (given a social context) connectedness with those around them (“I love everyone”).

During the 1990s, Ecstasy’s popularity soared as a “club drug” taken at night- clubs and all - night raves (Landry, 2002). The drug’s popularity crosses national borders, with an estimated 60 million tablets consumed annually in Britain (ACMD, 2009). There are, however, reasons not to be ecstatic about Ecstasy. One is its dehydrating effect, which—when combined with prolonged dancing—can lead to severe overheating, increased blood pressure, and death. Another is that long - term, repeated leaching of brain serotonin can damage serotonin - producing neurons, leading to decreased output and increased risk of permanently depressed mood (Croft et al., 2001; McCann et al., 2001; Roiser et al., 2005). Ecstasy also suppresses the disease - fighting immune system, impairs memory, slows thought, and disrupts sleep by interfering with serotonin’s control of the circadian clock (Laws & Kokkalis, 2007; Pacifici et al., 2001; Schilt et al., 2007). Ecstasy delights for the night but dispirits the morrow.

Hallucinogens

3-16: What are hallucinogens, and what are their effects?

Hallucinogens distort perceptions and evoke sensory images in the absence of sensory input (which is why these drugs are also called psychedelics, meaning

“mind- manifesting”). Some, such as LSD and MDMA (Ecstasy), are synthetic. Others, including the mild hallucinogen marijuana, are natural substances.

LSD Chemist Albert Hofmann created—and on one Friday afternoon in April 1943 accidentally ingested—LSD (lysergic acid diethyl amide). The result—“an uninter- rupted stream of fantastic pictures, extraordinary shapes with intense, kaleidoscopic play of colors” —reminded him of a childhood mystical experience that had left him long- ing for another glimpse of “a miraculous, powerful, unfathomable reality” (Siegel, 1984; Smith, 2006).

The emotions of an LSD trip vary from euphoria to detachment to panic. The user’s cur- rent mood and expectations color the emotional experience, but the perceptual distortions and hallucinations have some commonalities. Whether provoked to hallucinate by drugs, loss of oxygen, or extreme sensory deprivation, the brain hallucinates in basically the same way (Siegel, 1982). The experience typically begins with simple geometric forms, such as a lattice, cobweb, or spiral. The next phase consists of more meaningful images; some may be superimposed on a tunnel or funnel, others may be replays of past emotional experiences. As the hallucination peaks, people frequently feel separated from their body and experience dreamlike scenes so real that they may become panic-stricken or harm themselves.

These sensations are strikingly similar to the near- death experience, an altered state of consciousness reported by about 15 percent of patients revived from cardiac arrest (Agrillo, 2011; Greyson, 2010). Many describe visions of tunnels (FIGURE 3.20 on the next page), bright lights or beings of light, a replay of old memories, and out - of - body sensations (Siegel, 1980). Given that oxygen deprivation and other insults to the brain are known to produce hallucinations, it is difficult to resist wondering whether a brain under stress manufactures the near - death experience. Following temporal lobe seizures, patients have reported similarly profound mystical experiences. So have solitary sailors and polar explorers while enduring monotony, isolation, and cold (Suedfeld & Mocellin, 1987).

The hug drug MDMA, known as Ecstasy, produces a euphoric high and feelings of intimacy. But repeated use can destroy serotonin- producing neurons and deflate mood and impair memory.

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methamphetamine a powerfully addictive drug that stimulates the central nervous system, with speeded-up body functions and associated energy and mood changes; over time, appears to reduce baseline dopamine levels.

Ecstasy (MDMA) a synthetic stimulant and mild hallucinogen. Produces euphoria and social intimacy, but with short - term health risks and longer - term harm to serotonin - producing neurons and to mood and cognition.

hallucinogens psychedelic (“mind - manifesting”) drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input.

LSD a powerful hallucinogenic drug; also known as acid (lysergic acid diethylamide).

near-death experience an altered state of consciousness reported after a close brush with death (such as through cardiac arrest); often similar to drug-induced hallucinations.

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108 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Marijuana For 5000 years, hemp has been cultivated for its fiber. The leaves and flowers of this plant, which are sold as marijuana, contain THC (delta - 9-tetrahydrocannabinol). Whether smoked (getting to the brain in about 7 seconds) or eaten (causing its peak con- centration to be reached at a slower, unpredictable rate), THC produces a mix of effects.

Marijuana is a difficult drug to classify. It is a mild hallucinogen, amplifying sensitivity to colors, sounds, tastes, and smells. But like alcohol, marijuana relaxes, disinhibits, and may produce a euphoric high. Both alcohol and marijuana impair the motor coordina- tion, perceptual skills, and reaction time necessary for safely operating an automobile or other machine. “THC causes animals to misjudge events,” reported Ronald Siegel (1990, p. 163). “Pigeons wait too long to respond to buzzers or lights that tell them food is available for brief periods; and rats turn the wrong way in mazes.”

Marijuana and alcohol also differ. The body eliminates alcohol within hours. THC and its by - products linger in the body for a week or more, which means that regular users may achieve a high with smaller amounts of the drug than would be needed by occasional users. This is contrary to the usual path of tolerance, in which repeat users need to take larger doses to feel the same effect.

A user’s experience can vary with the situation. If the person feels anxious or depressed, using marijuana may intensify these feelings. The more often the person uses marijuana, especially during adolescence, the greater the risk of anxiety or depression (Bambico et al., 2010; Hall, 2006; Murray et al., 2007). Daily use bodes a worse outcome than infrequent use.

Marijuana also disrupts memory formation and interferes with immediate recall of information learned only a few minutes before. Such cognitive effects outlast the period of smoking (Messinis et al., 2006). Heavy adult use for over 20 years is associated with a shrinkage of brain areas that process memories and emotions (Yücel et al., 2008). Pre- natal exposure through maternal marijuana use impairs brain development (Berghuis et al., 2007; Huizink & Mulder, 2006).

Some states and countries have passed laws allowing marijuana to be used for medi- cal purposes to relieve the pain and nausea associated with diseases such as AIDS and cancer (Munsey, 2010; Watson et al., 2000). In such cases, the Institute of Medicine recommends delivering the THC with medical inhalers. Marijuana smoke, like cigarette smoke, is toxic and can cause cancer, lung damage, and pregnancy complications.

* * * Despite their differences, the psychoactive drugs summarized in TABLE 3.3 share a common feature: They trigger negative aftereffects that offset their immediate posi- tive effects and grow stronger with repetition. And that helps explain both tolerance and withdrawal. As the opposing, negative aftereffects grow stronger, it takes larger and larger doses to produce the desired high (tolerance), causing the aftereffects to worsen in the drug’s absence (withdrawal). This in turn creates a need to switch off the withdrawal symptoms by taking yet more of the drug (which may lead to addiction).

THC the major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations.

FIGURE 3.20

Hallucination or near-death vision? Psychologist Ronald Siegel (1977) reported that people under the influence of hallucinogenic drugs often see “a bright light in the center of the field of vision. . . . The location of this point of light create[s] a tunnel-like perspective.” This is very similar to others’ near-death experiences.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 109

Table 3.3

A Guide to Selected Psychoactive Drugs

Drug Type Pleasurable Effects Adverse Effects

Alcohol Depressant Initial high followed by relaxation and disinhibition

Depression, memory loss, organ damage, impaired reactions

Heroin Depressant Rush of euphoria, relief from pain Depressed physiology, agonizing withdrawal

Caffeine Stimulant Increased alertness and wakefulness Anxiety, restlessness, and insomnia in high doses; uncomfortable withdrawal

Methamphet- amine

Stimulant Euphoria, alertness, energy Irritability, insomnia, hypertension, seizures

Cocaine Stimulant Rush of euphoria, confidence, energy Cardiovascular stress, suspiciousness, depressive crash

Nicotine Stimulant Arousal and relaxation, sense of well - being Heart disease, cancer

Ecstasy (MDMA)

Stimulant; mild hallucinogen

Emotional elevation, disinhibition Dehydration, overheating, depressed mood, impaired cognitive and immune functioning

Marijuana (THC)

Mild hallucinogen

Enhanced sensation, relief of pain, distortion of time, relaxation

Impaired learning and memory, increased risk of psycho- logical disorders, lung damage from smoke

RETRIEVE IT

“How strange would appear to be this thing that men call pleasure! And how curiously it is related to what is thought to be its opposite, pain! . . . Wherever the one is found, the other follows up behind.”

Plato, Phaedo, fourth century B.C.E.

• How does this pleasure-pain description apply to the repeated use of psychoactive drugs?

ANSWER: Psychoactive drugs create pleasure by altering brain chemistry. With repeated use of the drug, the brain develops tolerance and needs more of the drug to achieve the desired effect. (Marijuana is an exception.) As the user becomes dependent, discontinuing use of the substance produces painful or psychologically unpleasant withdrawal symptoms.

Influences on Drug Use

3-17: Why do some people become regular users of consciousness- altering drugs?

Drug use by North American youth increased during the 1970s. Then, with increased drug education and a more realistic and deglamorized media depiction of tak- ing drugs, drug use declined sharply. After the early 1990s, the cultural antidrug voice softened, and drugs for a time were again glamorized in some music and films. Consider, for example, historical trends in the use of marijuana:

• In the University of Michigan’s annual survey of 15,000 U.S. high school seniors, the proportion who said there is “great risk” in regular marijuana use rose from 35 percent in 1978 to 79 percent in 1991, then retreated to 47 percent in 2010 (Johnston et al., 2011).

• After peaking in 1978, marijuana use by U.S. high school seniors declined through 1992, then rose, but has recently been tapering off (see FIGURE 3.21 on the next page). Among Canadian 15- to 24-year-olds, 23 percent report using marijuana monthly, weekly, or daily (Health Canada, 2012).

For some adolescents, occasional drug use represents thrill seeking. Why, though, do others become regular drug users? In search of answers, researchers have engaged bio- logical, psychological, and social-cultural levels of analysis.

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110 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Biological Influences Some people may be biologically vulnerable to particular drugs. For example, heredity influences some aspects of substance abuse problems, especially those appearing by early adulthood (Crabbe, 2002):

• Having an identical rather than fraternal twin with alcohol dependence puts one at increased risk for alcohol problems. In marijuana use also, identical twins more closely resemble each other than do fraternal twins (Kendler et al., 2002).

• Boys who at age 6 are excitable, impulsive, and fearless (genetically influenced traits) are more likely as teens to smoke, drink, and use other drugs (Masse & Tremblay, 1997).

• Researchers have identified genes that are more common among people and ani- mals predisposed to alcohol dependence, and they are seeking genes that contribute to tobacco addiction (NIH, 2006; Nurnberger & Bierut, 2007). These culprit genes seemingly produce deficiencies in the brain’s natural dopamine reward system: While triggering temporary dopamine-produced pleasure, the addictive drugs dis- rupt normal dopamine balance. Studies of how drugs reprogram the brain’s reward systems raise hopes for anti-addiction drugs that might block or blunt the effects of alcohol and other drugs (Miller, 2008; Wilson & Kuhn, 2005).

Psychological and Social - Cultural Influences Throughout this text, you will see that biological, psychological, and social-cultural influences interact to produce behavior. So, too, with drug use (FIGURE 3.22). One psychological factor that has appeared in studies of youth and young adults is the feel- ing that life is meaningless and directionless (Newcomb & Harlow, 1986). This feeling is common among school dropouts who subsist without job skills, without privilege, and with little hope.

Sometimes the psychological influence is obvious. Many heavy users of alcohol, marijuana, and cocaine have experienced significant stress or failure and are depressed. Girls with a history of depression, eating disorders, or sexual or physical abuse are at risk for substance addiction. So are youth undergoing school or neighborhood transitions (CASA, 2003; Logan et al., 2002). Collegians who have not yet achieved a clear identity are also at greater risk (Bishop et al., 2005). By temporarily dulling the pain of self - awareness, psychoactive drugs may offer a way to avoid coping with depression, anger, anxiety, or insomnia. (As Chapter 7 explains, behavior is often controlled more by its immediate consequences than by its later ones.)

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60

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Nic -A - Teen Virtually nobody starts smok- ing past the vulnerable teen years. Eager to hook customers whose addiction will give them business for years to come, cigarette companies target teens. Portrayals of smoking by popular actors, such as Robert Pattinson in Remember Me, entice teens to imitate.

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Trends in drug use The percentage of U.S. high school seniors who report having used alcohol, marijuana, or cocaine during the past 30 days declined from the late 1970s to 1992, when it partially rebounded for a few years. (From Johnston et al., 2012.)

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 111

Smoking usually begins during early adolescence. (If you are in college or univer- sity, and the cigarette manufacturers haven’t yet made you their devoted customer, they almost surely never will.) Adolescents, self - conscious and often thinking the world is watching their every move, are vulnerable to smoking’s allure. They may first light up to imitate glamorous celebrities, or to project a mature image, or to get the social reward of being accepted by other smokers (Cin et al., 2007; Tickle et al., 2006). Mindful of these tendencies, cigarette companies have effectively modeled smoking with themes that appeal to youths: sophistication, independence, adventure- seeking, social approval. Typically, teens who start smoking also have friends who smoke, who suggest its plea- sures and offer them cigarettes (Rose et al., 1999). Among teens whose parents and best friends are nonsmokers, the smoking rate is close to zero (Moss et al., 1992; also see FIGURE 3.23). Most teen drinking is also done for social reasons, not as a way to cope with problems (Kuntsche et al., 2005).

Rates of drug use also vary across cultural and ethnic groups. One survey of 100,000 teens in 35 European countries found that marijuana use in the prior 30 days ranged from zero to 1 percent in Romania and Sweden, to 20 to 22 percent in Britain, Swit- zerland, and France (ESPAD, 2003). Independent U.S. government studies of drug use in households nationwide and among high schoolers in all regions reveal that African - American teens have sharply lower rates of drinking, smoking, and cocaine use (John- ston et al., 2007). Alcohol and other drug addiction rates have also been low among actively religious people, with extremely low rates among Orthodox Jews, Mormons, Mennonites, and the Amish (Trimble, 1994; Yeung et al., 2009). Relatively drug - free small towns and rural areas tend to constrain any genetic predisposition to drug use (Legrand et al., 2005). So does active parental monitoring (Lac & Crano, 2009). For those whose genetic predispositions nudge them toward substance use, cities offer more opportunities and less supervision.

Whether in cities or rural areas, peers influence attitudes about drugs. They also throw the parties and provide (or don’t provide) the drugs. If an adolescent’s friends use drugs, the odds are that he or she will, too. If the friends do not, the opportunity may not even arise. Teens who come from happy families, who do not begin drinking before age 15, and who do well in school tend not to use drugs, largely because they rarely associate with those who do (Bach- man et al., 2007; Hingson et al., 2006; Odgers et al., 2008).

Peer influence is more than what friends do or say. Adolescents’ expectations—what they believe friends are doing and favoring— influence their behavior (Vitória et al., 2009). One study surveyed sixth graders in 22 U.S. states. How many believed their friends had smoked marijuana? About 14 percent. How many of those friends acknowledged doing so? Only 4 percent

Biological influences:

Social-cultural influences:

Drug use

Psychological influences:

45%

30

15

0

Percentage of 11- to 17-year-olds

who smoked a cigarette at least once in the past

30 days

All/Most of my friends smoke

Some of my friends smoke

None of my friends smoke

Culture and alcohol Percentage drinking weekly or more: United States 30% Canada 40% Britain 58% (Gallup Poll, from Moore, 2006)

FIGURE 3.23

Peer influence Kids don’t smoke if their friends don’t (Philip Morris, 2003). A correlation-causation question: Does the close link between teen smoking and friends’ smoking reflect peer influence? Teens seeking similar friends? Or both?

FIGURE 3.22

Levels of analysis for drug use The biopsychosocial approach enables researchers to investigate drug use from complementary perspectives.

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112 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Table 3.4 Facts About “Higher” Education

College and university students drink more alcohol than their nonstudent peers and exhibit 2.5 times the general population’s rate of substance abuse.

Fraternity and sorority members report nearly twice the binge-drinking rate of nonmembers.

Since 1993, campus smoking rates have declined, alcohol use has been steady, and abuse of prescription opioids, stimulants, tranquilizers, and sedatives has increased, as has marijuana use.

Source: NCASA, 2007.

SNAPSHOTS

(Wren, 1999). University students are not immune to such misperceptions: Drinking dominates social occasions partly because students overestimate their fellow students’ enthusiasm for alcohol and underestimate their views of its risks (Prentice & Miller, 1993; Self, 1994) (TABLE 3.4). When students’ overestimates of peer drinking are cor- rected, alcohol use often subsides (Moreira et al., 2009).

People whose beginning use of drugs was influenced by their peers are more likely to stop using when friends stop or the social network changes (Kandel & Raveis, 1989). One study that followed 12,000 adults over 32 years found that smokers tend to quit in clusters (Christakis & Fowler, 2008). Within a social network, the odds of a person’s quitting increased when a spouse, friend, or co-worker stopped smoking. Similarly, most soldiers who became drug addicted while in Vietnam ceased their drug use after return- ing home (Robins et al., 1974).

As always with correlations, the traffic between friends’ drug use and our own may be two - way: Our friends influence us. Social networks matter. But we also select as friends those who share our likes and dislikes.

What do the findings on drug use suggest for drug prevention and treatment pro- grams? Three channels of influence seem possible:

• Educate young people about the long - term costs of a drug’s temporary pleasures. • Help young people find other ways to boost their self - esteem and purpose in life. • Attempt to modify peer associations or to “inoculate” youths against peer pressures

by training them in refusal skills.

People rarely abuse drugs if they understand the physical and psychological costs, feel good about themselves and the direction their lives are taking, and are in a peer group that disapproves of using drugs. These educational, psychological, and social-cultural fac- tors may help explain why 26 percent of U.S. high school dropouts, but only 6 percent of those with a postgraduate education, report smoking (CDC, 2011).

RETRIEVE IT

• Studies have found that people who begin drinking in the early teens are much more likely to become alcohol dependent than are those who begin at age 21 or after. What possible explanations might there be for this correlation between early use and later abuse?

ANSWER: Possible explanations include (a) a biological predisposition to both early use and later abuse; (b) brain changes and taste preferences triggered by early use; and (c) enduring habits, attitudes, activities, or peer relationships that foster alcohol abuse.

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 113

CHAPTER REVIEW

Consciousness and the Two-Track Mind

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the chapter). Then turn to Appendix D, Complete Chapter Reviews, to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

The Brain and Consciousness 3–1: What is the place of consciousness in psychology’s

history?

3–2: What is the “dual-processing” being revealed by today’s cognitive neuroscience?

3–3: How much information do we consciously attend to at once?

Sleep and Dreams 3–4: How do our biological rhythms influence our daily

functioning?

3–5: What is the biological rhythm of our sleeping and dreaming stages?

3–6: How do biology and environment interact in our sleep patterns?

3–7: What are sleep’s functions?

3–8: How does sleep loss affect us, and what are the major sleep disorders?

3–9: What do we dream?

3–10: What are the functions of dreams?

Hypnosis 3–11: What is hypnosis, and what powers does a

hypnotist have over a hypnotized subject?

3–12: Is hypnosis an extension of normal consciousness or an altered state?

Drugs and Consciousness 3–13: What are tolerance, dependence, and addiction,

and what are some common misconceptions about addiction?

3–14: What are depressants, and what are their effects?

3–15: What are stimulants, and what are their effects?

3–16: What are hallucinogens, and what are their effects?

3–17: Why do some people become regular users of consciousness-altering drugs?

LEARNING OBJECTIVES

Test yourself on these terms by trying to write down the definition in your own words before flipping back to the referenced page to check your answer.

consciousness, p. 78

cognitive neuroscience, p. 78

dual processing, p. 79

blindsight, p. 79

selective attention, p. 80

inattentional blindness, p. 81

change blindness, p. 82

circadian [ser - KAY-dee - an] rhythm, p. 83

REM sleep, p. 84

alpha waves, p. 85

sleep, p. 85

hallucinations, p. 85

delta waves, p. 85

suprachiasmatic nucleus, p. 87

insomnia, p. 91

narcolepsy, p. 92

sleep apnea, p. 92

night terrors, p. 93

dream, p. 93

manifest content, p. 94

latent content, p. 95

TERMS AND CONCEPTS TO REMEMBER

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114 CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

1. Failure to see visible objects because our attention is occupied elsewhere is called .

2. We register and react to stimuli outside of our awareness by means of processing. When we devote deliberate attention to stimuli, we use processing.

3. Our body temperature tends to rise and fall in sync with a biological clock, which is referred to as .

4. During Stage NREM-1 sleep, a person is most likely to experience

a. sleep spindles. b. hallucinations. c. night terrors or nightmares. d. rapid eye movements.

5. The brain emits large, slow delta waves during sleep.

6. As the night progresses, what happens to the REM stage of sleep?

7. Which of the following is NOT one of the theories that have been proposed to explain why we need sleep?

a. Sleep has survival value. b. Sleep helps us recuperate. c. Sleep rests the eyes. d. Sleep plays a role in the growth process.

8. What is the difference between narcolepsy and sleep apnea?

9. In interpreting dreams, Freud was most interested in their a. information-processing function. b. physiological function. c. manifest content, or story line. d. latent content, or hidden meaning.

10. What is the neural activation theory of dreaming?

11. “For what one has dwelt on by day, these things are seen in visions of the night” (Menander of Athens [342–292 B.C.E.], Fragments). How might the information-processing perspec- tive on dreaming interpret this quote?

12. The tendency for REM sleep to increase following REM sleep deprivation is referred to as .

13. People who are hypnotizable and will carry out a hypnotic suggestion typically

a. are able to focus totally on a task. b. have low self-esteem. c. are subject to hallucinations. d. are faking their actions.

14. Most experts agree that hypnosis can be effectively used to a. elicit testimony about a “forgotten” event. b. re-create childhood experiences. c. relieve pain. d. block sensory input.

15. Hilgard believed that hypnosis involves a state of divided consciousness, or .

16. After continued use of a psychoactive drug, the drug user needs to take larger doses to get the desired effect. This is referred to as .

17. The depressants include alcohol, barbiturates, a. and opiates. b. cocaine, and morphine. c. caffeine, nicotine, and marijuana. d. and amphetamines.

REM rebound, p. 96

hypnosis, p. 97

posthypnotic suggestion, p. 98

dissociation, p. 99

psychoactive drug, p. 100

tolerance, p. 100

addiction, p. 101

withdrawal, p. 102

physical dependence, p. 102

psychological dependence, p. 102

depressants, p. 102

alcohol dependence, p. 102

barbiturates, p. 103

opiates, p. 103

stimulants, p. 104

amphetamines, p. 104

nicotine, p. 104

methamphetamine, p. 106

Ecstasy (MDMA), p. 107

hallucinogens, p. 107

LSD, p. 107

near - death experience, p. 107

THC, p. 108

EXPERIENCE THE TESTING EFFECT

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CHAPTER 3 CONSCIOUSNESS AND THE TWO-TRACK MIND 115

18. Why might alcohol make a person more helpful or more aggressive?

19. Long-term use of Ecstasy can a. depress sympathetic nervous system activity. b. deplete the brain’s supply of epinephrine. c. deplete the brain’s supply of dopamine. d. damage serotonin-producing neurons.

20. Near-death experiences are strikingly similar to the halluci- nations evoked by .

21. Use of marijuana a. impairs motor coordination, perception, reaction time,

and memory. b. inhibits people’s emotions.

c. leads to dehydration and overheating. d. stimulates brain cell development.

22. An important psychological contributor to drug use is a. inflated self-esteem. b. the feeling that life is meaningless and directionless. c. genetic predispositions. d. overprotective parents.

Find answers to these questions in Appendix E, in the back of the book.

Multiple-format self-tests and more may be found at www.worthpublishers.com/myers.

Experience more of the

TESTING EFFECT

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DEVELOPMENTAL PSYCHOLOGY’S MAJOR ISSUES

PRENATAL DEVELOPMENT AND THE NEWBORN Conception

Prenatal Development

The Competent Newborn

INFANCY AND CHILDHOOD Physical Development

Cognitive Development

CLOSE-UP: Autism and “Mind-Blindness”

Social Development

Reflections on Nature and Nurture

ADOLESCENCE Physical Development

Cognitive Development

Social Development

THINKING CRITICALLY ABOUT: How Much Credit or Blame Do Parents Deserve?

Emerging Adulthood

Reflections on Continuity and Stages

ADULTHOOD Physical Development

Cognitive Development

Social Development

Reflections on Stability and Change

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117

Developing Through the Life Span Life is a journey, from womb to tomb. So it is for me, and so it will be for you. My story, and yours, began when a man and a woman

contributed 20,000+ genes to an egg that became a unique person. Those genes coded

the protein building blocks that, with astonishing precision, formed our bodies and predisposed our traits. My grandmother bequeathed to my mother a rare hearing-loss pattern, which she, in turn, gave to me (the least of her gifts). My father was an amiable extravert, and sometimes I forget to stop talking. As a child, my talking was impeded by painful stuttering, for which Seattle Public Schools gave me speech therapy.

Along with my parents’ nature, I also received their nurture. Like you, I was born into a particular family and culture, with its own way of viewing the world.

My values have been shaped by a family culture filled with talking and laughter, by a religious culture that speaks of love and justice, and by an academic culture that encourages critical thinking (asking, What do you mean? How do you know?).

We are formed by our genes, and by our contexts, so our stories will differ. But in many ways we are each like nearly everyone else on Earth.

Being human, you and I have a need to belong. My mental video library, which began after age 4, is filled with scenes of social attachment. Over

time, my attachments to parents loosened as peer friendships grew. After lacking confidence to date in high school, I fell in love with a college classmate and mar- ried at age 20. Natural selection disposes us to survive and perpetuate our genes. Sure enough, two years later a child entered our lives and I experienced a new form of love that surprised me with its intensity.

But life is marked by change. That child now lives 2000 miles away, and one of his two siblings has found her calling in South Africa. The tight rubber bands linking parent and child have loosened, as yours likely have as well.

Change also marks most vocational lives, which for me transitioned from a teen working in the family insurance agency, to a premed chemis- try major and hospital aide, to (after discarding my half-completed medi- cal school applications) a psychology professor and author. I predict that in 10 years you, too, will be doing things you do not currently anticipate.

Stability also marks our development. When I look in the mirror I do not see the person I once was, but I feel like the person I have always been. I am the same person who, as a late teen, played basketball and discovered love. A half-century later, I still play basketball and still love (with less passion but more security) the life partner with whom I have shared life’s griefs and joys.

We experience a continuous self, but that self morphs through stages—growing up, raising children, enjoying a career, and, eventually, life’s final stage, which will demand my presence. As I wend my way through this cycle of life and death, I am mindful that life’s journey is a continuing process of development, seeded by nature and shaped by nurture, animated by love and focused by work, begun with wide-eyed curiosity and completed, for those blessed to live to a good old age, with peace and never-ending hope.

Across the life span we grow from newborn to toddler, from toddler to teenager, and from teen to mature adult. At each stage of life’s journey there are physical, cognitive, and social milestones. Let’s begin at the very beginning.

CHAPTERR4

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118 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Developmental Psychology’s Major Issues

4-1: What three issues have engaged developmental psychologists?

Developmental psychology examines our physical, cognitive, and social development across the life span, with a focus on three major issues:

1. Nature and nurture: How does our genetic inheritance (our nature) interact with our experiences (our nurture) to influence our development? How have your nature and your nurture influenced your life story?

2. Continuity and stages: What parts of development are gradual and continuous, like riding an escalator? What parts change abruptly in separate stages, like climbing rungs on a ladder?

3. Stability and change: Which of our traits persist through life? How do we change as we age?

We will reflect on these three developmental issues throughout this chapter.

Prenatal Development and the Newborn

4-2: What is the course of prenatal development, and how do teratogens affect that development?

Conception Nothing is more natural than a species reproducing itself. And nothing is more won- drous. With humans, the process starts when a woman’s ovary releases a mature egg—a cell roughly the size of the period at the end of this sentence. Like space voyagers approaching a huge planet, the 200 million or more deposited sperm begin their race upstream, approaching a cell 85,000 times their own size. The relatively few reaching the egg release digestive enzymes that eat away its protective coating (FIGURE 4.1a). As soon as one sperm penetrates that coating and is welcomed in (Figure 4.1b), the egg’s surface blocks out the others. Before half a day elapses, the egg nucleus and the sperm nucleus fuse. The two have become one.

Consider it your most fortunate of moments. Among 200 million sperm, the one needed to make you, in combination with that one particular egg, won the race. And

so it was for innumerable genera- tions before us. If any one of our ancestors had been conceived with a different sperm or egg, or died before conceiving, or not chanced to meet the partner or . . . the mind boggles at the improbable, unbro- ken chain of events that produced you and me.

First known photo of Michael Phelps (If the playful cartoonist were to convey literal truth, a second arrow would also point to the egg that contributed the other half of Michael Phelps’ genes.) ©

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“Nature is all that a man brings with him into the world; nurture is every influence that affects him after his birth.”

Francis Galton, English Men of Science, 1874

developmental psychology a branch of psychology that studies physical, cognitive, and social change throughout the life span.

zygote the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo.

embryo the developing human organism from about 2 weeks after fertilization through the second month.

fetus the developing human organism from 9 weeks after conception to birth.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 119

Prenatal Development Fewer than half of all fertilized eggs, called zygotes, survive beyond the first 2 weeks (Grobstein, 1979; Hall, 2004). But for you and me, good fortune prevailed. One cell became 2, then 4—each just like the first—until this cell division had produced some 100 identical cells within the first week. Then the cells began to differentiate—to spe- cialize in structure and function. How identical cells do this—as if one decides “I’ll become a brain, you become intestines!”—is a puzzle that scientists are just beginning to solve.

About 10 days after conception, the zygote attaches to the mother’s uterine wall, beginning approximately 37 weeks of the closest human relationship. The zygote’s inner cells become the embryo (FIGURE 4.2a). The outer cells become the placenta, the life- link that transfers nutrients and oxygen from mother to embryo. Over the next 6 weeks, the embryo’s organs begin to form and function. The heart begins to beat.

By 9 weeks after conception, an embryo looks unmistakably human (Figure 4.2b). It is now a fetus (Latin for “offspring” or “young one”). During the sixth month, organs such as the stomach have developed enough to give the fetus a chance of survival if born prematurely.

At each prenatal stage, genetic and environmental factors affect our development. By the sixth month, microphone readings taken inside the uterus reveal that the fetus is responsive to sound and is exposed to the sound of its mother’s muffled voice (Ecklund- Flores, 1992; Hepper, 2005). Immediately after birth, newborns prefer her voice to another woman’s or to their father’s (Busnel et al., 1992; DeCasper et al., 1984, 1986, 1994). They also prefer hearing their mother’s language. If she spoke two languages dur- ing pregnancy, they display interest in both (Byers-Heinlein et al., 2010). And just after birth, the melodic ups and downs of newborns’ cries bear the tuneful signature of their

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FIGURE 4.1 Life is sexually transmitted (a) Sperm cells surround an egg. (b) As one sperm penetrates the egg’s jelly-like outer coating, a series of chemical events begins that will cause sperm and egg to fuse into a single cell. If all goes well, that cell will subdivide again and again to emerge 9 months later as a 100-trillion- cell human being.

FIGURE 4.2 Prenatal development (a) The embryo grows and develops rapidly. At 40 days, the spine is visible and the arms and legs are beginning to grow. (b) By the end of the second month, when the fetal period begins, facial features, hands, and feet have formed. (c) As the fetus enters the fourth month, its 3 ounces could fit in the palm of your hand.

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120 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

moodboard/JupiterImages

Prenatal development zygote: conception to 2 weeks embryo: 2 weeks through 8 weeks fetus: 9 weeks to birth

teratogens (literally, “monster maker”) agents, such as toxins, chemicals, and viruses, that can reach the embryo or fetus during pre- natal development and cause harm.

fetal alcohol syndrome (FAS) physical and cognitive abnormalities in children caused by a pregnant woman’s heavy drinking. In severe cases, symptoms include noticeable facial misproportions.

“You shall conceive and bear a son. So then drink no wine or strong drink.”

Judges 13:7

“I felt like a man trapped in a woman’s body. Then I was born.”

Comedian Chris Bliss

mother’s native tongue (Mampe et al., 2009). Babies born to French-speaking moth- ers tend to cry with the rising intonation of French; babies born to German-speaking mothers cry with the falling tones of German. Would you have guessed? The learning of language begins in the womb.

In the two months before birth, fetuses demonstrate learning in other ways, as when they adapt to a vibrating, honking device placed on their mother’s abdomen (Dirix et al., 2009). Like people who adapt to the sound of trains in their neighborhood, fetuses get used to the honking. Moreover, four weeks later, they recall the sound (as evidenced by their blasé response, compared with the reactions of those not previously exposed).

Sounds are not the only stimuli fetuses are exposed to in the womb. In addition to transferring nutrients and oxygen from mother to fetus, the placenta screens out many harmful substances, but some slip by. Teratogens, agents such as toxins, viruses, and drugs, can damage an embryo or fetus. This is one reason pregnant women are advised not to drink alcoholic beverages. A pregnant woman never drinks alone. As alcohol enters her bloodstream, and her fetus’, it depresses activity in both their central nervous systems. Alcohol use during pregnancy may prime the woman’s offspring to like alcohol and may put them at risk for heavy drinking and alcohol dependence during their teens. In experiments, when pregnant rats drank alcohol, their young offspring later displayed a liking for alcohol’s taste and odor (Youngentob et al., 2007, 2009).

Even light drinking or occasional binge drinking can affect the fetal brain (Braun, 1996; Ikonomidou et al., 2000; Sayal et al., 2009). Persistent heavy drinking puts the fetus at risk for birth defects and for future behavior problems, hyperactivity, and lower intelligence. For 1 in about 800 infants, the effects are visible as fetal alcohol syn- drome (FAS), marked by a small, misproportioned head and lifelong brain abnor- malities (May & Gossage, 2001). The fetal damage may occur because alcohol has what Chapter 2 called an epigenetic effect: It leaves chemical marks on DNA that switch genes abnormally on or off (Liu et al., 2009).

RETRIEVE IT

• The first two weeks of prenatal development is the period of the

. The period of the

lasts from 9 weeks after conception until birth. The time between those two prenatal periods is considered the period of the

.

ANSWERS: zygote; fetus; embryo

The Competent Newborn

4-3: What are some newborn abilities, and how do researchers explore infants’ mental abilities?

Babies come with software preloaded on their neural hard drives. Having sur- vived prenatal hazards, we as newborns came equipped with automatic reflex responses ideally suited for our survival. We withdrew our limbs to escape pain. If a cloth over our face interfered with our breathing, we turned our head from side to side and swiped at it.

New parents are often in awe of the coordinated sequence of reflexes by which their baby gets food. When something touches their cheek, babies turn toward that touch, open their mouth, and vigorously root for a nipple. Finding one, they automatically close on it and begin sucking—which itself requires a coordinated sequence of reflexive tongu- ing, swallowing, and breathing. Failing to find satisfaction, the hungry baby may cry—a behavior parents find highly unpleasant and very rewarding to relieve.

The pioneering American psychologist William James presumed that newborns experience a “blooming, buzzing confusion,” an assumption few people challenged until the 1960s. Then scientists discovered that babies can tell you a lot—if you know how to ask. To ask, you must capitalize on what babies can do—gaze, suck, turn their heads. So,

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 121

equipped with eye - tracking machines and paci- fiers wired to electronic gear, researchers set out to answer parents’ age - old questions: What can my baby see, hear, smell, and think?

Consider how researchers exploit habituation— a decrease in responding with repeated stimulation. We saw this earlier when fetuses adapted to a vibrat- ing, honking device placed on their mother’s abdo- men. The novel stimulus gets attention when first presented. With repetition, the response weakens. This seeming boredom with familiar stimuli gives us a way to ask infants what they see and remember.

Indeed, even as newborns, we prefer sights and sounds that facilitate social respon- siveness. We turn our heads in the direction of human voices. We gaze longer at a draw- ing of a face-like image (FIGURE 4.3). We prefer to look at objects 8 to 12 inches away, which—wonder of wonders—just happens to be the approximate distance between a nursing infant’s eyes and its mother’s (Maurer & Maurer, 1988).

Within days after birth, our brain’s neural networks were stamped with the smell of our mother’s body. Week - old nursing babies, placed between a gauze pad from their mother’s bra and one from another nursing mother, have usually turned toward the smell of their own mother’s pad (MacFarlane, 1978). What’s more, that smell prefer- ence lasts. One experiment capitalized on the fact that some nursing moth- ers in a French maternity ward used a chamomile-scented balm to prevent nipple soreness (Delaunay-El Allam, 2010). Twenty-one months later, their toddlers preferred playing with chamo- mile-scented toys! Their peers who had not sniffed the scent while breast feeding showed no such preference. (This makes me wonder: Will adults, who as babies associated chamomile scent with their mother’s breast, become devoted chamomile tea drinkers?)

Infancy and Childhood As a flower unfolds in accord with its genetic instructions, so do we humans. Maturation— the orderly sequence of biological growth—decrees many of our commonalities. We stand before walking. We use nouns before adjectives. Severe deprivation or abuse can retard our development, but the genetic growth tendencies are inborn. Maturation (nature) sets the basic course of development; experience (nurture) adjusts it. Once again, we see genes and scenes interacting.

Physical Development

4-4: During infancy and childhood, how do the brain and motor skills develop?

Brain Development The formative nurture that conspired with nature began at conception, with the pre- natal environment in the womb. Nurture continues outside the womb, where our early experiences foster brain development.

habituation decreasing responsiveness with repeated stimulation. As infants gain familiarity with repeated exposure to a visual stimulus, their interest wanes and they look away sooner.

maturation biological growth processes that enable orderly changes in behavior, rela- tively uninfluenced by experience.

Prepared to feed and eat Animals are predisposed to respond to their offsprings’ cries for nourishment.

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FIGURE 4.3 Newborns’ preference for faces When shown these two stimuli with the same elements, Italian newborns spent nearly twice as many seconds looking at the face-like image (Johnson & Morton, 1991). Canadian newborns—average age 53 minutes in one study—displayed the same apparently inborn preference to look toward faces (Mondloch et al., 1999).

“It is a rare privilege to watch the birth, growth, and first feeble struggles of a living human mind.”

Annie Sullivan, in Helen Keller’s The Story of My Life, 1903

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122 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

In your mother’s womb, your developing brain formed nerve cells at the explosive rate of nearly one - quarter million per minute. From infancy on, brain and mind—neural hardware and cognitive software—develop together. On the day you were born, you had most of the brain cells you would ever have. However, the wiring among these cells—your nervous system—was immature: After birth, these neural networks had a wild growth spurt branching and link- ing in patterns that would eventually enable you to walk, talk, and remember (FIGURE 4.4).

From ages 3 to 6, the most rapid brain growth was in your frontal lobes, which enable rational planning. During those years, your ability to control your attention and behavior developed rapidly (Garon et al., 2008; Thompson- Schill et al., 2009).

Frontal lobe development continues into adolescence and beyond. The last cortical areas to develop are the association areas—those linked with thinking, memory, and language. As they develop, mental abilities surge (Chugani & Phelps, 1986; Thatcher et al., 1987). The neural pathways supporting language and agility proliferate into puberty. Then, a use-it-or-lose-it pruning process shuts down unused links and strengthens others (Paus et al., 1999; Thompson et al., 2000).

Your genes dictated your overall brain architecture, rather like the lines of a coloring book, but experience fills in the details (Kenrick et al., 2009). So how do early experi- ences leave their “marks” in the brain? Mark Rosenzweig and David Krech opened a window on that process when they raised some young rats in solitary confinement in an impoverished environment, and others in a communal playground that simulated a natural environment. When the researchers later analyzed the rats’ brains, those who died with the most toys had won. The rats living in the enriched environment had usually developed a heavier and thicker brain cortex (FIGURE 4.5).

Rosenzweig was so surprised by this discovery that he repeated the experiment several times before publishing his findings (Renner & Rosenzweig, 1987; Rosenzweig, 1984). So great are the effects that, shown brief video clips, you could tell from the rats’ activity and curiosity whether their environment had been impoverished or enriched (Renner & Renner, 1993). After 60 days in the enriched environment, the rats’ brain weights increased 7 to 10 percent and the number of synapses mushroomed by about 20 percent (Kolb & Whishaw, 1998).

Such results have motivated improvements in environments for laboratory, farm, and zoo animals—and for children in institutions. Stimulation by touch or massage also ben- efits infant rats and premature babies (Field et al., 2007). “Handled” infants of both species develop faster neurologically and gain weight more rapidly. By giving preemies massage therapy, neonatal intensive care units help them to go home sooner (Field et al., 2006).

Nature and nurture together sculpt our synapses. Brain maturation provides us with an abundance of neural connections. Experiences—sights and smells, touches and tugs—activate and strengthen some neural pathways while others weaken from disuse. Like forest pathways, popular tracks are broadened and less-traveled ones gradually dis- appear. The result by puberty is a massive loss of unemployed connections.

At birth 3 months 15 months

Stringing the circuits young String musicians who started playing before age 12 have larger and more complex neural circuits controlling the note - making left- hand fingers than do string musicians whose training started later (Elbert et al., 1995).

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FIGURE 4.5 Experience affects brain development Mark Rosenzweig and David Krech raised rats either alone in an environment without playthings, or with other rats in an environment enriched with playthings changed daily. In 14 of 16 repetitions of this basic experiment, rats in the enriched environment developed significantly more cerebral cortex (relative to the rest of the brain’s tissue) than did those in the impoverished environment.

Impoverished environment

Impoverished rat brain cell

Enriched environment

Enriched rat brain cell

FIGURE 4.4 Drawings of human cerebral cortex sections In humans, the brain is immature at birth. As the child matures, the neural networks grow increasingly complex.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 123

Here at the juncture of nurture and nature is the biological reality of early childhood learning. During early childhood—while excess connections are still on call—young- sters can most easily master such skills as the grammar and accent of another language. We seem to have a critical period for some skills. Lacking any exposure to spoken, written, or signed language before adolescence, a person will never master any language (see Chapter 9). Likewise, lacking visual experience during the early years, a person whose vision is restored by cataract removal will never achieve normal perceptions (more on this in Chapter 6). Without stimulation, the brain cells normally assigned to vision will die during the pruning process or be diverted to other uses. The maturing brain’s rule: Use it or lose it.

Although normal stimulation during the early years is critical, the brain’s develop- ment does not end with childhood. As we saw in Chapter 2’s discussion of brain plastic- ity, our neural tissue is ever changing and new neurons are born. If a monkey pushes a lever with the same finger several thousand times a day, brain tissue controlling that finger changes to reflect the experience. Human brains work similarly (FIGURE 4.6). Whether learning to keyboard or skateboard, we perform with increasing skill as our brain incorporates the learning (Ambrose, 2010).

Motor Development The developing brain enables physical coordination. As an infant’s muscles and nervous system mature, skills emerge. With occasional exceptions, the sequence of physical (motor) development is universal. Babies roll over before they sit unsup- ported, and they usually crawl on all fours before they walk (FIGURE 4.7). These behaviors reflect not imitation but a maturing nervous system; blind children, too, crawl before they walk.

There are, however, individual differences in timing. In the United States, for exam- ple, 25 percent of all babies walk by 11 months of age, 50 percent within a week after their first birthday, and 90 percent by age 15 months (Frankenburg et al., 1992). The recommended infant back - to - sleep position (putting babies to sleep on their backs to reduce the risk of a smothering crib death) has been associated with somewhat later crawling but not with later walking (Davis et al., 1998; Lipsitt, 2003).

Genes guide motor development. Identical twins typically begin walking on nearly the same day (Wilson, 1979). Maturation— including the rapid development of the cerebellum at the back of the brain—creates our readiness to learn walking at about age 1. Experience before that time has a limited effect. The same is true for other physical skills, including bowel and bladder control. Before necessary muscular and neural maturation, neither pleading nor punishment will produce successful toilet training.

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“Genes and experiences are just two ways of doing the same thing—wiring synapses.”

Joseph LeDoux, The Synaptic Self, 2002

In the eight years following the 1994 launch of a U.S. Back to Sleep educational campaign, the number of infants sleeping on their stomach dropped from 70 to 11 percent—and SIDS (sudden infant death syndrome) deaths fell by half (Braiker, 2005).

critical period an optimal period early in the life of an organism when exposure to certain stimuli or experiences produces normal development.

FIGURE 4.7 Physical development Sit, crawl, walk, run—the sequence of these motor development milestones is the same the world around, though babies reach them at varying ages.

FIGURE 4.6 A trained brain A well - learned finger - tapping task activates more motor cortex neurons (orange area, right) than were active in the same brain before training (left). (From Karni et al., 1998.)

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124 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN M

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cognition all the mental activities associ- ated with thinking, knowing, remembering, and communicating.

schema a concept or framework that orga- nizes and interprets information.

assimilation interpreting our new experi- ences in terms of our existing schemas.

accommodation adapting our current understandings (schemas) to incorporate new information.

RETRIEVE IT

• The biological growth process, called

, explains why most children begin walking by about 12 to 15 months.

ANSWER: maturation

Brain Maturation and Infant Memory Can you recall your first day of preschool or your third birthday party? Our earliest memories seldom predate our third birthday. We see this infantile amnesia in the memo- ries of some preschoolers who experienced an emergency fire evacuation caused by a burning popcorn maker. Seven years later, they were able to recall the alarm and what caused it—if they were 4 to 5 years old at the time. Those experiencing the event as 3-year - olds could not remember the cause and usually misrecalled being already out- side when the alarm sounded (Pillemer, 1995). Other studies have confirmed that the average age of earliest conscious memory is 3.5 years (Bauer, 2002, 2007). As children mature, from 4 to 6 to 8 years, childhood amnesia is giving way, and they become increasingly capable of remembering experiences, even for a year or more (Bruce et al., 2000; Morris et al., 2010). The brain areas underlying memory, such as the hippocampus and frontal lobes, continue to mature into adolescence (Bauer, 2007).

Although we consciously recall little from before age 4, our brain was processing and storing information during those early years. In 1965, while finishing her doctoral work in psychology, Carolyn Rovee-Collier observed an infant memory. She was a new mom, whose colicky 2-month-old, Benjamin, could be calmed by moving a crib mobile. Weary of hitting the mobile, she strung a cloth ribbon connecting the mobile to Benjamin’s foot. Soon, he was kicking his foot to move the mobile. Thinking about her unintended home experiment, Rovee-Collier realized that, contrary to popular opinion in the 1960s, babies are capable of learning. To know for sure that her son wasn’t just a whiz kid, she repeated the experiment with other infants (Rovee-Collier, 1989, 1999). Sure enough, they, too, soon kicked more when hitched to a mobile, both on the day of the experiment and the day after. They had learned the link between moving legs and moving mobiles. If, however, she hitched them to a different mobile the next day, the infants showed no learning, indicating that they remembered the original mobile and recognized the difference. Moreover, when tethered to the familiar mobile a month later, they remembered the association and again began kicking (FIGURE 4.8).

Traces of forgotten childhood languages may also persist. One study tested English- speaking British adults who had no conscious memory of the Hindi or Zulu they had spoken as children. Yet, up to age 40, they could relearn subtle sound contrasts in these languages that other people could not learn (Bowers et al., 2009). What the conscious mind does not know and cannot express in words, the nervous system and our two- track mind somehow remembers.

Cognitive Development

4-5: From the perspectives of Piaget, Vygotsky, and today’s researchers, how does a child’s mind develop?

Cognition refers to all the mental activities associated with thinking, know- ing, remembering, and communicating. Somewhere on your life journey, you became conscious. When was that, and how did your mind unfold from there? Developmental psychologist Jean Piaget [pee - ah- ZHAY] spent his life searching for the answers to such questions. His interest began in 1920, when he was in Paris developing questions for children’s intelligence tests. While administering the tests, Piaget became intrigued by children’s wrong answers, which were often strikingly similar among same-age children. Where others saw childish mistakes, Piaget saw intelligence at work.

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FIGURE 4.8 Infant at work Babies only 3 months old can learn that kicking moves a mobile, and they can retain that learning for a month. (From Rovee - Collier, 1989, 1997.)

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 125

A half - century spent with children convinced Piaget that a child’s mind is not a miniature model of an adult’s. Thanks partly to his work, we now understand that children reason differently than adults, in “wildly illogical ways about problems whose solutions are self - evident to adults” (Brainerd, 1996).

Piaget’s studies led him to believe that a child’s mind develops through a series of stages, in an upward march from the new- born’s simple reflexes to the adult’s abstract reasoning power. Thus, an 8-year - old can comprehend things a toddler cannot, such as the analogy that “getting an idea is like having a light turn on in your head,” or that a miniature slide is too small for slid- ing, and a miniature car is much too small to get into (FIGURE 4.9).

Piaget’s core idea is that the driving force behind our intellectual progression is an unceasing struggle to make sense of our experiences. To this end, the maturing brain builds schemas, concepts or mental molds into which we pour our experiences (FIGURE 4.10). By adulthood we have built countless schemas, ranging from cats and dogs to our concept of love.

To explain how we use and adjust our schemas, Piaget proposed two more concepts. First, we assimilate new experiences—we interpret them in terms of our current understandings (schemas). Having a simple schema for dog, for example, a toddler may call all four-legged animals dogs. But as we interact with the world, we also adjust, or accommodate, our schemas to incorporate information provided by new experiences. Thus, the child soon learns that the original dog schema is too broad and accommodates by refining the category.

Jean Piaget (1896–1980) “If we examine the intellectual development of the individual or of the whole of humanity, we shall find that the human spirit goes through a certain number of stages, each different from the other” (1930).

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FIGURE 4.9 Scale errors Psychologists Judy DeLoache, David Uttal, and Karl Rosengren (2004) have reported that 18- to 30-month- old children may fail to take the size of an object into account when trying to perform impossible actions with it. At left, a 21-month - old attempts to slide down a miniature slide. At right, a 24-month - old opens the door to a miniature car and tries to step inside.

FIGURE 4.10 An impossible object Look carefully at this “devil’s tuning fork.” Now look away—no, better first study it some more—and then look away and draw it. . . . Not so easy, is it? Because this tuning fork is an impossible object, you have no schema for such an image.

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126 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Piaget’s Theory and Current Thinking Piaget believed that children construct their understanding of the world while interacting with it. Their minds experience spurts of change, followed by greater stability as they move from one cognitive plateau to the next, each with distinctive characteristics that permit specific kinds of thinking. TABLE 4.1 summarizes the four stages in Piaget’s theory.

Sensorimotor Stage In the sensorimotor stage, from birth to nearly age 2, babies take in the world through their senses and actions—through looking, hearing, touching, mouthing, and grasping. As their hands and limbs begin to move, they learn to make things happen.

Very young babies seem to live in the present: Out of sight is out of mind. In one test, Piaget showed an infant an appealing toy and then flopped his beret over it. Before the age of 6 months, the infant acted as if the toy ceased to exist. Young infants lack object permanence—the awareness that objects continue to exist when not perceived. By 8 months, infants begin exhibiting memory for things no longer seen. If you hide a toy, the infant will momentarily look for it (FIGURE 4.11). Within another month or two, the infant will look for it even after being restrained for several seconds.

So does object permanence in fact blossom at 8 months, much as tulips blossom in spring? Today’s researchers think not. They believe object permanence unfolds gradually,

Table 4.1

Piaget’s Stages of Cognitive Development

Typical Age Range Description of Stage Developmental Phenomena

Birth to nearly 2 years

Sensorimotor Experiencing the world through senses and actions (looking, hearing, touching, mouthing, and grasping)

• Object permanence

• Stranger anxiety

About 2 to about 6 or 7 years

Preoperational Representing things with words and images; using intuitive rather than logi- cal reasoning

• Pretend play

• Egocentrism

About 7 to 11 years Concrete operational Thinking logically about concrete events; grasping concrete analogies and performing arithmetical operations

• Conservation

• Mathematical transformations

About 12 through adulthood

Formal operational Abstract reasoning

• Abstract logic

• Potential for mature moral reasoning

Pretend play

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FIGURE 4.11 Object permanence Infants younger than 6 months seldom understand that things continue to exist when they are out of sight. But for this older infant, out of sight is definitely not out of mind.

sensorimotor stage in Piaget’s theory, the stage (from birth to about 2 years of age) during which infants know the world mostly in terms of their sensory impressions and motor activities.

object permanence the awareness that things continue to exist even when not perceived.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 127

(a) Objects placed in case (b) Screen comes up (c) Empty hand enters (d) One object removed

(e) Screen drops revealing 1 object

or: impossible outcome

(f ) Screen drops revealing 2 objects

FIGURE 4.12 Baby math Shown a numerically impossible outcome, 5-month-old infants stare longer. (From Wynn, 1992.)

and they see development as more continuous than Piaget did. Even young infants will at least momentarily look for a toy where they saw it hidden a second before (Wang et al., 2004).

Researchers also believe Piaget and his followers underestimated young children’s competence. Consider these simple experiments:

• Baby physics: Like adults staring in disbelief at a magic trick (the “Whoa!” look), infants look longer at an unexpected and unfamiliar scene of a car seeming to pass through a solid object, a ball stopping in midair, or an object violating object perma- nence by magically disappearing (Baillargeon, 1995, 2008; Wellman & Gelman, 1992).

• Baby math: Karen Wynn (1992, 2000) showed 5-month - olds one or two objects (FIGURE 4.12a). Then she hid the objects behind a screen, and visibly removed or added one (Figure 4.12d). When she lifted the screen, the infants sometimes did a double take, staring longer when shown a wrong number of objects (Figure 4.12f). But were they just responding to a greater or smaller mass of objects, rather than a change in number (Feigenson et al., 2002)? Later experiments showed that babies’ number sense extends to larger numbers, to ratios, and to such things as drum- beats and motions (Libertus & Brannon, 2009; McCrink & Wynn, 2004; Spelke & Kinzler, 2007). If accustomed to a Daffy Duck puppet jumping three times on stage, they showed surprise if it jumped only twice.

Clearly, infants are smarter than Piaget appreciated. Even as babies, we had a lot on our minds.

Preoperational Stage Piaget believed that until about age 6 or 7, children are in a preoperational stage—too young to perform mental operations (such as imagining an action and mentally reversing it). For a 5-year - old, the milk that seems “too much” in a tall, narrow glass may become an acceptable amount if poured into a short, wide glass. Focusing only on the height dimension, this child cannot perform the operation of mentally pouring the milk back. Before about age 6, said Piaget, children lack the con- cept of conservation—the principle that quantity remains the same despite changes in shape (FIGURE 4.13).

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FIGURE 4.13 Piaget’s test of conservation This preoperational child does not yet understand the principle of conservation of substance. When the milk is poured into a tall, narrow glass, it suddenly seems like “more” than when it was in the shorter, wider glass. In another year or so, she will understand that the volume stays the same.

preoperational stage in Piaget’s theory, the stage (from about 2 to about 6 or 7 years of age) during which a child learns to use language but does not yet comprehend the mental operations of concrete logic.

conservation the principle (which Piaget believed to be a part of concrete operational reasoning) that properties such as mass, volume, and number remain the same despite changes in the forms of objects.

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128 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

PRETEND PLAY A child who can perform mental operations can think in symbols and therefore begins to enjoy pretend play. Contemporary researchers have found that symbolic thinking appears at an earlier age than Piaget supposed. Judy DeLoache (1987) showed children a model of a room and hid a miniature stuffed dog behind its miniature couch. The 21⁄2-year - olds easily remembered where to find the miniature toy, but they could not use the model to locate an actual stuffed dog behind a couch in a real room. Three - year - olds—only 6 months older—usually went right to the actual stuffed animal in the real room, showing they could think of the model as a symbol for the room. Piaget did not view the stage transitions as abrupt shifts. Even so, he probably would have been surprised to see symbolic thinking at such an early age.

EGOCENTRISM Piaget contended that preschool children are egocentric: They have difficulty perceiving things from another’s point of view. Asked to “show Mommy your picture,” 2-year - old Gabriella holds the picture up facing her own eyes. Three - year- old Gray makes himself “invisible” by putting his hands over his eyes, assuming that if he can’t see his grandparents, they can’t see him. Children’s conversations also reveal their egocentrism, as one young boy demonstrated (Phillips, 1969, p. 61):

“Do you have a brother?”

“Yes.”

“What’s his name?”

“Jim.”

“Does Jim have a brother?”

“No.”

Like Gabriella, TV-watching preschoolers who block your view of the TV assume that you see what they see. They simply have not yet developed the ability to take another’s viewpoint. Even we adults may overestimate the extent to which others share our opinions and perspectives, a trait known as the curse of knowledge. We assume that something will be clear to others if it is clear to us, or that e-mail recipients will “hear” our “just kidding” intent (Epley et al., 2004; Kruger et al., 2005). Children are even more susceptible to such egocentrism.

THEORY OF MIND When Little Red Riding Hood realized her “grandmother” was really a wolf, she swiftly revised her ideas about the creature’s intentions and raced away. Preschoolers, although still egocentric, develop this ability to infer others’ mental states when they begin forming a theory of mind (a term first coined by psychologists David Premack and Guy Woodruff [1978], to describe chimpanzees’ seeming ability to read intentions).

As the ability to take another’s perspective gradually develops, preschoolers come to understand what made a playmate angry, when a sibling will share, and what might make a parent buy a toy. And they begin to tease, empathize, and persuade. Between about 31⁄2 and 41 ⁄2, children worldwide come to realize that others may hold false beliefs (Callaghan et al., 2005; Sabbagh et al., 2006). Jennifer Jenkins and Janet Astington (1996) showed Toronto children a Band-Aids box and asked them what was inside. Expecting Band-Aids, the children were surprised to discover that the box actually contained pen- cils. Asked what a child who had never seen the box would think was inside, 3-year - olds typically answered “pencils.” By age 4 to 5, the children’s theory of mind had leapt for- ward, and they anticipated their friends’ false belief that the box would hold Band-Aids. Children with autism (see Close - Up: Autism and “Mind Blindness,” next page) have difficulty understanding that another’s state of mind differs from their own.

Concrete Operational Stage By age 6 or 7, said Piaget, children enter the con- crete operational stage. Given concrete (physical) materials, they begin to grasp con- servation. Understanding that change in form does not mean change in quantity, they can mentally pour milk back and forth between glasses of different shapes. They also enjoy jokes that use this new understanding:

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“It’s too late, Roger—they’ve seen us.”

Roger has not outgrown his early childhood egocentrism.

egocentrism in Piaget’s theory, the preop- erational child’s difficulty taking another’s point of view.

theory of mind people’s ideas about their own and others’ mental states—about their feel- ings, perceptions, and thoughts, and the behav- iors these might predict.

concrete operational stage in Piaget’s theory, the stage of cognitive devel- opment (from about 6 or 7 to 11 years of age) during which children gain the mental opera- tions that enable them to think logically about concrete events.

formal operational stage in Piaget’s theory, the stage of cognitive development (normally beginning about age 12) during which people begin to think logically about abstract concepts.

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Mr. Jones went into a restaurant and ordered a whole pizza for his dinner. When the waiter asked if he wanted it cut into 6 or 8 pieces, Mr. Jones said, “Oh, you’d better make it 6, I could never eat 8 pieces!” (McGhee, 1976)

Piaget believed that during the concrete operational stage, children become able to comprehend mathematical transformations and conservation. When my daughter, Laura, was 6, I was astonished at her inability to reverse simple arithmetic. Asked, “What is 8 plus 4?” she required 5 seconds to compute “12,” and another 5 seconds to then com- pute 12 minus 4. By age 8, she could answer a reversed question instantly.

Formal Operational Stage By about age 12, our reasoning expands from the purely concrete (involving actual experience) to encompass abstract thinking (involving imag- ined realities and symbols). As children approach adolescence, said Piaget, many become capable of thinking more like scientists. They can ponder hypothetical propositions and deduce consequences: If this, then that. Systematic reasoning, what Piaget called formal operational thinking, is now within their grasp.

Although full - blown logic and reasoning await adolescence, the rudiments of formal operational thinking begin earlier than Piaget realized. Consider this simple problem:

If John is in school, then Mary is in school. John is in school. What can you say about Mary?

Formal operational thinkers have no trouble answering correctly. But neither do most 7-year - olds (Suppes, 1982).

An Alternative Viewpoint: Lev Vygotsky and the Social Child As Piaget was forming his theory of cognitive development, Russian psychologist Lev Vygotsky (1896–1934) was also studying how children think and learn. He noted that by age 7, they increasingly think in words and use words to solve problems. They do this, he said, by internalizing their culture’s language and relying on inner speech (Fernyhough, 2008). Parents who say “No, no!” when pulling a child’s hand away from a cake are giving the child a self - control tool. When the child later needs to resist temptation, he may likewise say “No, no!” Second- graders who muttered to themselves while doing math problems grasped third - grade math better the following year (Berk, 1994). Whether out loud or inaudibly, talking to themselves helps children control their behavior and emotions and master new skills.

Where Piaget emphasized how the child’s mind grows through interaction with the physical environment, Vygotsky emphasized how the child’s mind grows through interaction with the social environment. If Piaget’s child was a young scientist, Vygotsky’s was a young apprentice. By mentoring children and giving them new words, parents and others provide a temporary scaffold from which children can step to higher levels of thinking (Renninger & Granott, 2005). Language, an important ingredient of social mentoring, provides the building blocks for thinking, noted Vygotsky (who was born the same year as Piaget, but died prematurely of tuberculosis).

Reflecting on Piaget’s Theory What remains of Piaget’s ideas about the child’s mind? Plenty—enough to merit his being singled out by Time magazine as one of the twentieth century’s 20 most influ- ential scientists and thinkers and rated in a survey of British psychologists as the last century’s greatest psychologist (Psychologist, 2003). Piaget identified significant cognitive milestones and stimulated worldwide interest in how the mind develops. His empha- sis was less on the ages at which children typically reach specific milestones than on their sequence. Studies around the globe, from aboriginal Australia to Algeria to North America, have confirmed that human cognition unfolds basically in the sequence Piaget described (Lourenco & Machado, 1996; Segall et al., 1990).

However, today’s researchers see development as more continuous than did Piaget. By detecting the beginnings of each type of thinking at earlier ages, they have revealed conceptual abilities Piaget missed. Moreover, they view formal logic as a smaller part of cognition than he did. Piaget would not be surprised that today, as part of our own cognitive development, we are adapting his ideas to accommodate new findings.

“Assessing the impact of Piaget on developmental psychology is like assessing the impact of Shakespeare on English literature.”

Developmental psychologist Harry Beilin (1992)

Lev Vygotsky (1896–1934) Vygotsky, a Russian developmental psychologist pic- tured here with his daughter, studied how a child’s mind feeds on the language of social interaction.

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130 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Implications for Parents and Teachers Future parents and teachers, remember this: Young children are incapable of adult logic. Preschoolers who block one’s view of the TV simply have not learned to take another’s viewpoint. What seems simple and obvious to us—getting off a teeter-totter will cause a friend on the other end to crash—may be incomprehensible to a 3-year-old. Also remember that children are not

Autism and “Mind-Blindness”

CLOSE UP:

is Asperger syndrome, a high-functioning form of autism. Asperger syndrome is marked by normal intelligence, often accompanied by exceptional skill or talent in a specific area, but deficient social and communication skills and a tendency to become distracted by irrelevant stimuli (Remington et al., 2009).

Autism afflicts four boys for every girl. Children for whom amniotic fluid analyses indicated high prenatal testosterone develop more masculine and autistic traits (Auyeung et al., 2009). Psychologist Simon Baron-Cohen (2008, 2009) argues that autism represents an “extreme male brain.” Girls are naturally predisposed to be “empathizers,” he contends. They are better at reading facial expressions and gestures, though less so if given testosterone (van Honk et al., 2011). Reading faces is a chal- lenging task for those with autism. Although the sexes overlap, boys are, Baron-Cohen believes, better “systemizers”—better at understanding things according to rules or laws, as in math- ematical and mechanical systems.

“If two ‘systemizers’ have a child, this will increase the risk of the child having autism,” Baron-Cohen theorizes. And because of assortative mating—people’s tendency to seek spouses who share their interests—two

systemizers will indeed often mate. “I do not discount environmental factors,” he notes. “I’m just saying, don’t forget about biology.”

Twin and sibling studies provide some evi- dence for biology’s influence. If one identical twin is diagnosed with autism, the chances are 50 to 70 percent that the co-twin will also receive this diagnosis (Lichtenstein et al., 2010; Sebat et al., 2007). A younger sibling of a child with autism also is at a heightened risk (Sutcliffe, 2008). Random genetic muta- tions in sperm-producing cells may also play a role. As men age, these mutations become more frequent, which may help explain why an over-40 man has a much higher risk of father- ing a child with autism than does a man under 30 (Reichenberg et al., 2007). Researchers are now sleuthing autism spectrum disorder’s

Diagnoses of autism, a disorder marked by social deficiencies, have been increasing. Once believed to affect 1 in 2500 children, autism or a related disorder now affects 1 in 110 Ameri- can children and about 1 in 100 in Britain (CDC, 2009; Lilienfeld & Arkowitz, 2007; NAS, 2011). The increase in autism diagnoses has been offset by a decrease in the number of children considered “cognitively disabled” or “learn- ing disabled,” which suggests a relabeling of children’s disorders (Gernsbacher et al., 2005; Grinker, 2007; Shattuck, 2006). A massive $6.7 billion National Children’s Study now under way aims to enroll 100,000 pregnant women in 105 countries and to follow their babies until they turn 21. Researchers hope this study will help explain the rising rates of autism, as well as premature births, childhood obesity, and asthma (Belluck, 2010; Murphy, 2008).

The underlying source of autism’s symp- toms seems to be poor communication among brain regions that normally work together to let us take another’s viewpoint. People with autism are therefore said to have an impaired theory of mind (Rajendran & Mitchell, 2007; Senju et al., 2009). They have difficulty infer- ring others’ thoughts and feelings. They do not appreciate that playmates and parents might view things differently. Mind reading that most of us find intuitive (Is that face conveying a smirk or a sneer?) is difficult for those with autism. Most children learn that another child’s pouting mouth signals sadness, and that twin- kling eyes mean happiness or mischief. A child with autism fails to understand these signals (Frith & Frith, 2001). In hopes of a cure, des- perate parents have sometimes subjected chil- dren to ineffective therapies (Shute, 2010).

Autism spectrum disorder is a term used to encompass a range of variations, one of which

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Autism case number 1 In 1943, Donald Gray Triplett, an “odd” child with unusual gifts and social deficits, was the first person to receive the diagnosis of a previously unreported condition, which psychiatrist Leo Kanner termed autism. In 2010, at age 77, Triplett was still living in his native home and Mississippi town, where he often played golf (Donvan & Zucker, 2010).

autism a disorder that appears in childhood and is marked by deficient communication, social interaction, and understanding of others’ states of mind.

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passive receptacles waiting to be filled with knowledge. Better to build on what they already know, engaging them in concrete demonstrations and stimulating them to think for themselves. Finally, accept children’s cognitive immaturity as adaptive. It is nature’s strategy for keeping children close to protective adults and providing time for learning and socialization (Bjorklund & Green, 1992).

telltale signs in the brain’s synaptic and gray matter (Crawley, 2007; Ecker et al., 2010; Gar- ber, 2007).

Biology’s role in autism also appears in brain-function studies. People without autism often yawn after seeing others yawn. And as they view and imitate another’s smiling or frowning, they feel something of what the other is feeling. Not so among those with autism spectrum disorder, who are less imitative and show much less activity in brain areas involved in mirroring others’ actions (Dapretto et al., 2006; Perra et al., 2008; Senju et al., 2007). When people with autism watch another per- son’s hand movements, for example, their brain displays less-than-normal mirroring activity (Oberman & Ramachandran, 2007; Théoret et al., 2005). Scientists are continuing to explore and vigorously debate the idea that the brains of people with autism have “broken mirrors” (Gallese et al., 2011).

Seeking to “systemize empathy,” Baron- Cohen and his Cambridge University colleagues

(2007; Golan et al., 2010) collaborated with Britain’s National Autistic Society and a film production company. Knowing that television shows with vehicles have been popular among kids with autism, they created animations with toy vehicle characters in a pretend boy’s bed- room, grafting emotion-conveying faces onto toy trams, trains, and tractors (FIGURE 4.14). After the boy leaves for school, the characters

come to life and have experiences that lead them to display various emotions (which I pre- dict you would enjoy viewing at www.thetrans- porters.com). The children were surprisingly able to generalize what they had learned to a new, real context. By the intervention’s end, their previously deficient ability to recognize emotions on real faces equaled that of children without autism.

RETRIEVE IT

• What does theory of mind have to do with autism?

ANSWER: Theory of mind focuses on our ability to understand our own and others’ mental states. Those with autism struggle with this ability.

“The neighbor’s dog has bitten people before. He is barking at Louise.”

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After intervention, children with autism become better able to identify which facial emotion matches the context.

Accuracy scores

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(b) Children matched the correct face with the story. (The graph above shows data for two trials.)

Point to the face that shows how Louise is feeling.

(a) Emotion-conveying faces were grafted onto toy trains.

FIGURE 4.14 Transported into a world of emotion (a) A research team at Cambridge University’s Autism Research Centre introduced children with autism to emotions experienced and displayed by toy vehicles. (b) After four weeks of viewing animations, the children displayed a markedly increased ability to recognize emotions not only in the toy faces but also in humans.

“Childhood has its own way of seeing, thinking, and feeling, and there is nothing more foolish than the attempt to put ours in its place.”

Philosopher Jean - Jacques Rousseau, 1798

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132 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

RETRIEVE IT

• Object permanence, pretend play, conservation, and abstract logic are developmental milestones for which of Piaget’s stages, respectively?

ANSWER: Object permanence for the sensorimotor stage, pretend play for the preoperational stage, conservation for the concrete operational stage, and abstract logic for the formal operational stage.

• Match the developmental phenomena (1–6) to the correct cognitive developmental stage (a–d).

a. Sensorimotor b. Preoperational c. Concrete operational d. Formal operational

1. Thinking about abstract concepts, such as “freedom.”

2. Enjoying imaginary play (such as dress-up).

3. Understanding that physical properties stay the same even when objects change form.

4. Ability to reverse math operations.

5. Understanding that something is not gone for good when it disappears from sight, as when Mom “disappears” behind the shower curtain.

6. Difficulty taking another’s point of view (as when blocking someone’s view of the TV).

ANSWERS: 1. d, 2. b, 3. c, 4. c, 5. a, 6. b

Social Development

4-6: How do parent-infant attachment bonds form?

From birth, babies are social creatures, developing an intense bond with their caregivers. Infants come to prefer familiar faces and voices, then to coo and

gurgle when given a parent’s attention. After about 8 months, soon after object perma- nence emerges and children become mobile, a curious thing happens: They develop stranger anxiety. They may greet strangers by crying and reaching for familiar caregiv- ers. “No! Don’t leave me!” their distress seems to say. Children this age have schemas for familiar faces; when they cannot assimilate the new face into these remembered sche- mas, they become distressed (Kagan, 1984). Once again, we see an important principle: The brain, mind, and social - emotional behavior develop together.

Origins of Attachment One-year-olds typically cling tightly to a parent when they are frightened or expect separation. Reunited after being apart, they shower the parent with smiles and hugs. No social behavior is more striking than the intense and mutual infant - parent bond. This attachment bond is a powerful survival impulse that keeps infants close to their care- givers. Infants become attached to those—typically their parents—who are comfortable and familiar. For many years, psychologists reasoned that infants became attached to those who satisfied their need for nourishment. It made sense. But an accidental finding overturned this explanation.

Body Contact During the 1950s, University of Wisconsin psychologists Harry Har- low and Margaret Harlow bred monkeys for their learning studies. To equalize experi- ences and to isolate any disease, they separated the infant monkeys from their mothers shortly after birth and raised them in sanitary individual cages, which included a cheese- cloth baby blanket (Harlow et al., 1971). Then came a surprise: When their blankets were taken to be laundered, the monkeys became distressed.

The Harlows recognized that this intense attachment to the blanket contradicted the idea that attachment derives from an association with nourishment. But how could they show this more convincingly? To pit the drawing power of a food source against the contact comfort of the blanket, they created two artificial mothers. One was a bare wire cylinder with a wooden head and an attached feeding bottle, the other a cylinder wrapped with terry cloth.

Stranger anxiety A newly emerging abil- ity to evaluate people as unfamiliar and pos- sibly threatening helps protect babies 8 months and older.

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stranger anxiety the fear of strangers that infants commonly display, beginning by about 8 months of age.

attachment an emotional tie with another person; shown in young children by their seek- ing closeness to the caregiver and showing distress on separation.

imprinting the process by which certain animals form attachments during a critical period very early in life.

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When raised with both, the monkeys overwhelmingly preferred the comfy cloth mother (FIGURE 4.15). Like other infants clinging to their live mothers, the mon- key babies would cling to their cloth mothers when anxious. When exploring their environment, they used her as a secure base, as if attached to her by an invisible elastic band that stretched only so far before pulling them back. Researchers soon learned that other qualities—rocking, warmth, and feeding—made the cloth mother even more appealing.

Human infants, too, become attached to parents who are soft and warm and who rock, feed, and pat. Much parent - infant emotional communication occurs via touch (Hertenstein et al., 2006), which can be either soothing (snuggles) or arousing (tickles). Human attachment also consists of one person providing another with a secure base from which to explore and a safe haven when distressed. As we mature, our secure base and safe haven shift—from parents to peers and partners (Cassidy & Shaver, 1999). But at all ages we are social creatures. We gain strength when some- one offers, by words and actions, a safe haven: “I will be here. I am interested in you. Come what may, I will support you” (Crowell & Waters, 1994).

Familiarity Contact is one key to attachment. Another is familiarity. In many animals, attachments based on familiarity form during a critical period—an opti- mal period when certain events must take place to facilitate proper development (Bornstein, 1989). As noted earlier, humans seem to have a critical period for language. Goslings, ducklings, and chicks have a critical period for attachment, called imprinting, which falls in the hours shortly after hatching, when the first moving object they see is normally their mother. From then on, the young fowl follow her, and her alone.

Konrad Lorenz (1937) explored this rigid attachment process. He wondered: What would ducklings do if he was the first moving creature they observed? What they did was follow him around: Everywhere that Konrad went, the ducks were sure to go. Although baby birds imprint best to their own species, they also will imprint on a vari- ety of moving objects—an animal of another species, a box on wheels, a bouncing ball (Colombo, 1982; Johnson, 1992). Once formed, this attachment is difficult to reverse.

Children—unlike ducklings—do not imprint. However, they do become attached to what they’ve known. Mere exposure to people and things fosters fondness (see Chap- ter 13). Children like to reread the same books, rewatch the same movies, reenact family traditions. They prefer to eat familiar foods, live in the same familiar neighbor- hood, attend school with the same old friends. Familiarity is a safety signal. Familiarity breeds content.

Imprinting Whooping cranes normally learn to migrate by following their parents. These cranes, hand-raised from eggs, imprinted on a crane-costumed ultralight pilot, who then guided them to winter nesting grounds (Mooal- lem, 2009).Ma

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FIGURE 4.15 The Harlows’ mothers Psychologists Harry Harlow and Margaret Harlow raised monkeys with two artificial mothers—one a bare wire cylinder with a wooden head and an attached feeding bottle, the other a cylinder with no bottle but covered with foam rubber and wrapped with terry cloth. The Harlows’ discovery surprised many psychologists: The infants much preferred contact with the comfortable cloth mother, even while feeding from the nourishing mother.

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134 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

RETRIEVE IT

• What distinguishes imprinting from attachment?

ANSWER: Attachment is the normal process by which we form emotional ties with important others. Imprinting occurs only in certain animals that have a critical period very early in their development during which they must form their attachments, and they do so in an inflexible manner.

Attachment Differences

4-7: How have psychologists studied attachment differences, and what have they learned?

What accounts for children’s attachment differences? To answer this question, Mary Ainsworth (1979) designed the strange situation experiment. She observed mother- infant pairs at home during their first six months. Later she observed the 1-year - old infants in a strange situation (usually a laboratory playroom). Such research has shown that about 60 percent of infants display secure attachment. In their mother’s presence they play comfortably, happily exploring their new environment. When she leaves, they become distressed; when she returns, they seek contact with her.

Other infants avoid attachment or show insecure attachment, marked either by anxiety or avoidance of trusting relationships. They are less likely to explore their surround- ings; they may even cling to their mother. When she leaves, they either cry loudly and remain upset or seem indifferent to her departure and return (Ainsworth, 1973, 1989; Kagan, 1995; van IJzendoorn & Kroonenberg, 1988).

Ainsworth and others found that sensitive, responsive mothers—those who noticed what their babies were doing and responded appropriately—had infants who exhibited secure attachment (De Wolff & van IJzendoorn, 1997). Insensitive, unresponsive moth- ers—mothers who attended to their babies when they felt like doing so but ignored them at other times—often had infants who were insecurely attached. The Harlows’ monkey studies, with unresponsive artificial mothers, produced even more striking effects. When put in strange situations without their artificial mothers, the deprived infants were terrified (FIGURE 4.16).

But is attachment style the result of parenting? Or are other factors also at work?

Temperament and Attachment How does temperament—a person’s charac- teristic emotional reactivity and intensity—affect attachment style? Temperament is genetically influenced. Shortly after birth, some babies are noticeably difficult—irritable, intense, and unpredictable. Others are easy—cheerful, relaxed, and feeding and sleeping on predictable schedules (Chess & Thomas, 1987).

The genetic effect appears in physiological differences. Anxious, inhibited infants have high and variable heart rates and a reactive nervous system. When facing new or strange situ- ations, they become more physiologically aroused (Kagan & Snidman, 2004). One form of a gene that regulates the neurotransmitter serotonin predisposes a fearful temperament and, in combination with unsupportive caregiving, an inhibited child (Fox et al., 2007).

Temperament differences typically persist. Consider:

• The most emotionally reactive newborns have tended also to be the most reactive 9-month-olds (Wilson & Matheny, 1986; Worobey & Blajda, 1989).

• Exceptionally inhibited and fearful 2-year - olds often were still relatively shy as 8-year - olds; about half became introverted adolescents (Kagan et al., 1992, 1994).

• The most emotionally intense preschoolers have tended to be relatively intense young adults (Larsen & Diener, 1987). In one long-term study of more than 900 New Zealanders, emotionally reactive and impulsive 3-year - olds developed into somewhat more impulsive, aggressive, and conflict - prone 21-year - olds (Caspi, 2000).

Such evidence supports the conclusion that our biologically rooted temperament helps form our enduring personality (McCrae et al., 2000, 2007; Rothbart et al., 2000).

Harlow Primate Laboratory, University of Wisconsin

“Oh, he’s cute, all right, but he’s got the temperament of a car alarm.”

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FIGURE 4.16 Social deprivation and fear In the Harlows’ experiments, monkeys raised with artificial mothers were terror - stricken when placed in strange situations without those mothers. (Today’s climate of greater respect for animal welfare prevents such primate studies.)

temperament a person’s characteristic emotional reactivity and intensity.

basic trust according to Erik Erikson, a sense that the world is predictable and trustworthy; said to be formed during infancy by appropriate experiences with responsive caregivers.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 135

Parenting studies that neglect such inborn differences, noted Judith Harris (1998), do the equivalent of “comparing foxhounds reared in kennels with poodles reared in apartments.” To separate the effects of nature and nurture on attachment, we would need to vary parenting while controlling temperament. (Pause and think: If you were the researcher, how might you have done this?)

Dutch researcher Dymphna van den Boom’s solution was to ran- domly assign 100 temperamentally difficult 6- to 9-month - olds to either an experimental group, in which mothers received personal training in sensitive responding, or to a control group, in which they did not. At 12 months of age, 68 percent of the experimental group infants were rated securely attached, as were only 28 percent of the control group infants. Other studies have confirmed that intervention programs can increase parental sensitivity and, to a lesser extent, infant attachment security (Bakermans - Kranenburg et al., 2003; Van Zeijl et al., 2006).

As many of these examples indicate, researchers have more often studied mother care than father care, but fathers are more than just mobile sperm banks. Despite the widespread attitude that “fathering a child” means impregnating, and “mothering” means nurturing, nearly 100 studies worldwide have shown that a father’s love and acceptance are comparable to a mother’s love in predicting an offspring’s health and well - being (Rohner & Veneziano, 2001). In one mammoth British study follow- ing 7259 children from birth to adulthood, those whose fathers were most involved in parenting (through outings, reading to them, and taking an interest in their education) tended to achieve more in school, even after controlling for other factors such as paren- tal education and family wealth (Flouri & Buchanan, 2004). Fathers matter.

Children’s anxiety over separation from parents peaks at around 13 months, then gradually declines (FIGURE 4.17). This happens whether they live with one parent or two, are cared for at home or in a day - care center, live in North America, Guatemala, or the Kalahari Desert. Does this mean our need for and love of others also fades away? Hardly. Our capacity for love grows, and our pleasure in touching and holding those we love never ceases. The power of early attachment does nonetheless gradually relax, allowing us to move into a wider range of situations, communicate with strangers more freely, and stay emotionally attached to loved ones despite distance.

Attachment Styles and Later Relationships Developmental theorist Erik Erik- son (1902–1994), working with his wife, Joan Erikson, believed that securely attached children approach life with a sense of basic trust—a sense that the world is predictable and reliable. He attributed basic trust not to environment or inborn temperament, but to early parenting. He theorized that infants blessed with sensitive, loving caregivers form a lifelong attitude of trust rather than fear.

Although debate continues, many researchers now believe that our early attachments form the foundation for our adult relationships (Birnbaum et al., 2006; Fraley, 2002). Our adult styles of romantic love tend to exhibit secure, trusting attachment; inse- cure-anxious attachment; or insecure-avoidant attachment (Feeney & Noller, 1990; Rholes & Simpson, 2004; Shaver & Mikulincer, 2007). Feeling insecurely attached to others during childhood, for example, may take two main forms in adulthood (Fraley et al., 2011). One is anxiety, in which people constantly crave acceptance but remain vigilant to signs of possible rejection. The other is avoidance, in which people experience discomfort getting close to others and use avoidant strategies to maintain distance from others.

Adult attachment styles can also affect relationships with one’s own chil- dren. Avoidant people’s discomfort with closeness makes parenting more stressful and unsatisfying (Rholes et al., 2006). But say this for those (nearly half of all humans) who exhibit insecure attachments: Anxious or avoidant tendencies have helped our groups detect or escape dangers (Ein-Dor et al., 2010).

Full-time dad Financial analyst Walter Cranford, shown here with his baby twins, is one of a growing number of stay-at-home dads. Cranford says the experience has made him appreciate how difficult the work can be: “Sometimes at work you can just unplug, but with this you’ve got to be going all the time.”

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“Out of the conflict between trust and mistrust, the infant develops hope, which is the earliest form of what gradually becomes faith in adults.”

Erik Erikson (1983)

FIGURE 4.17 Infants’ distress over separation from parents In an experiment, groups of infants were left by their mothers in an unfamiliar room. In both groups, the percentage who cried when their mother left peaked at about 13 months. Whether the infant had experienced day care made little difference. (From Kagan, 1976.)

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136 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Deprivation of Attachment

4-8: How does childhood neglect or abuse affect children’s attachments?

If secure attachment fosters social trust, what happens when circumstances prevent a child’s forming attachments? In all of psychology, there is no sadder research literature. Babies locked away at home under conditions of abuse or extreme neglect are often withdrawn, frightened, even speechless. The same is true of those reared in institu- tions without the stimulation and attention of a regular caregiver, as was tragically illus- trated during the 1970s and 1980s in Romania. Having decided that economic growth for his impoverished country required more human capital, Nicolae Ceauşescu, Roma- nia’s Communist dictator, outlawed contraception, forbade abortion, and taxed families with fewer than five children. The birthrate indeed skyrocketed. But unable to afford the children they had been coerced into having, many families abandoned them to government-run orphanages with untrained and overworked staff. Child-to-caregiver ratios often were 15 to 1, so the children were deprived of healthy attachments with at least one adult. When tested after Ceauşescu was assassinated in 1989, these children had lower intelligence scores and double the 20 percent rate of anxiety symptoms found in children assigned to quality foster care settings (Nelson et al., 2009). Dozens of other studies across 19 countries have confirmed that orphaned children tend to fare better on later intelligence tests if raised in family homes. This is especially so for those placed at an early age (van IJzendoorn et al., 2008).

Most children growing up under adversity (as did the surviving children of the Holo- caust) are resilient; they become normal adults (Helmreich, 1992; Masten, 2001). So do most victims of childhood sexual abuse, notes Harvard researcher Susan Clancy (2010), while emphasizing that using children for sex is revolting and never the victim’s fault.

But others, especially those who experience no sharp break from their abusive past, don’t bounce back so readily. The Harlows’ monkeys raised in total isolation, without even an artificial mother, bore lifelong scars. As adults, when placed with other monkeys their age, they either cowered in fright or lashed out in aggression. When they reached sexual maturity, most were incapable of mating. If artificially impregnated, females often were neglectful, abusive, even murderous toward their first - born. Another primate experiment confirmed the abuse-breeds-abuse phenomenon in rhesus monkeys: 9 of 16 females who had been abused by their mothers became abusive parents, as did no female raised by a nonabusive mother (Maestripieri, 2005).

In humans, too, the unloved may become the unloving. Most abusive parents—and many condemned murderers—have reported being neglected or battered as children (Kempe & Kempe, 1978; Lewis et al., 1988). Some 30 percent of people who have been abused later

abuse their children—a rate lower than that found in the pri- mate study, but four times the U.S. national rate of child abuse (Dumont et al., 2007; Kaufman & Zigler, 1987).

Although most abused children do not later become violent criminals or abusive parents, extreme early trauma may nevertheless leave footprints on the brain. Abused children exhibit hypersensitivity to angry faces (Pollak, 2008). As adults, they exhibit stronger startle responses (Jovanovic et al., 2009). If repeatedly threatened and attacked while young, normally placid golden hamsters grow up to be cowards when caged with same - sized hamsters, or bullies when caged with weaker ones (Ferris, 1996). Such animals show changes in the brain chemical serotonin, which calms aggressive impulses. A similarly sluggish serotonin response has been found in abused chil- dren who become aggressive teens and adults. “Stress can

The deprivation of attachment In this Romanian orphanage, the 250 children between ages 1 and 5 outnumbered caregivers 10 to 1.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 137

set off a ripple of hormonal changes that permanently wire a child’s brain to cope with a malevolent world,” concluded abuse researcher Martin Teicher (2002).

Such findings help explain why young children who have survived severe or pro- longed physical abuse, childhood sexual abuse, or wartime atrocities are at increased risk for health problems, psychological disorders, substance abuse, and criminality (Freyd et al., 2005; Kendall-Tackett et al., 1993, 2004; Wegman & Stetler, 2009). Abuse victims are at considerable risk for depression if they carry a gene variation that spurs stress- hormone production (Bradley et al., 2008). As we will see again and again, behavior and emotion arise from a particular environment interacting with particular genes.

We adults also suffer when our attachment bonds are severed. Whether through death or separation, a break produces a predictable sequence. Agitated preoccupation with the lost partner is followed by deep sadness and, eventually, the beginnings of emotional detachment and a return to normal living (Hazan & Shaver, 1994). Newly separated couples who have long ago ceased feeling affection are sometimes surprised at their desire to be near the former partner. Deep and longstanding attachments seldom break quickly. Detaching is a process, not an event.

Day Care

4-9: How does day care affect children?

Developmental psychologists’ research has uncovered no major impact of maternal employment on children’s development, attachments, and achieve-

ments (Friedman & Boyle, 2008; Goldberg et al., 2008; Lucas-Thompson et al., 2010). Contemporary research now focuses on the effects of differing quality of day care on

different types and ages of children (Vandell et al., 2010). Sandra Scarr (1997) explained: Around the world, “high - quality child care consists of warm, supportive interactions with adults in a safe, healthy, and stimulating environment. . . . Poor care is boring and unresponsive to children’s needs.” Even well-run orphanages can produce healthy, thriv- ing children. In Africa and Asia, where more and more children are losing parents to AIDS and other diseases, orphanages typically are unlike those in Ceauşescu’s Romania, and the children living in quality orphanages fare about as well as those living in com- munities (Whetten et al., 2009).

Children thrive under varied types of responsive caregiving. Westernized attachment features one or two caregivers and their offspring, but multiple caregivers are the norm in other cultures, such as the Efe of Zaire (Field, 1996; Whaley et al., 2002). Even before an Efe mother holds her newborn, the baby is passed among several women. In the weeks to come, the infant will be constantly held (and fed) by other women and will form strong multiple attachments.

One ongoing study in 10 American cities has followed 1100 children since the age of 1 month. The researchers found that at ages 41⁄2 to 6, children who had spent the most time in day care had slightly advanced thinking and language skills. They also had an increased rate of aggressiveness and defiance (NICHD, 2002, 2003, 2006). But the child’s temperament, the parents’ sensitivity, and the family’s economic and educational level influenced aggression more than did the time spent in day care.

There is little disagreement that the children who merely exist for nine hours a day in understaffed centers deserve better. What all children need is a consistent, warm relationship with people they can learn to trust. The importance of such relationships extends beyond the preschool years, as Finn- ish psychologist Lea Pulkkinen (2006) observed in her career-long study of 285 individuals tracked from age 8 to 42. Her finding—that adult monitoring of children predicts favorable outcomes—led her to undertake, with support from Finland’s parliament, a nationwide program of adult-supervised activities for all first and second graders (Pulkkinen, 2004; Rose, 2004).

An example of high -quality day care Research has shown that young chil- dren thrive socially and intellectually in safe, stimulating environments with a ratio of one caregiver for every three or four children.

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Parenting Styles

4-10: What are three parenting styles, and how do children’s traits relate to them?

Some parents spank, some reason. Some are strict, some are lax. Some show little affection, some liberally hug and kiss. Do such differences in parenting styles affect children?

The most heavily researched aspect of parenting has been how, and to what extent, parents seek to control their children. Investigators have identified three parenting styles:

1. Authoritarian parents impose rules and expect obedience: “Don’t interrupt.” “Keep your room clean.” “Don’t stay out late or you’ll be grounded.” “Why? Because I said so.”

2. Permissive parents submit to their children’s desires. They make few demands and use little punishment.

3. Authoritative parents are both demanding and responsive. They exert control by setting rules, but, especially with older children, they encourage open discussion and allow exceptions.

Too hard, too soft, and just right, these styles have been called. Research indicates that children with the highest self - esteem, self - reliance, and social competence usually have warm, concerned, authoritative parents (Baumrind, 1996; Buri et al., 1988; Coopersmith, 1967). Those with authoritarian parents tend to have less social skill and self- esteem, and those with permissive parents tend to be more aggressive and immature. The participants in most studies have been middle - class White families, and some critics suggest that effec- tive parenting may vary by culture. Yet studies with families of other races and in more than 200 cultures worldwide have confirmed the social and academic correlates of loving and authoritative parenting (Rohner & Veneziano, 2001; Sorkhabi, 2005; Steinberg & Morris, 2001). For example, two studies of thousands of Germans found that those whose parents had maintained a curfew exhibited better adjustment and greater achievements in young adulthood than did those with permissive parents (Haase et al., 2008).

A word of caution: The association between certain parenting styles (being firm but open) and certain childhood outcomes (social competence) is correlational. Correla- tion is not causation. Perhaps you can imagine possible explanations for this parenting- competence link.

Parents who struggle with conflicting advice should also remember that all advice reflects the advice giver’s values. For parents who prize unquestioning obedience or whose children live in dangerous environments, an authoritarian style may have the desired

effect. For those who value children’s sociability and self - reliance, authoritative firm - but - open parenting is advisable.

Culture and Child Rearing Child-rearing practices reflect not only individual values, but also cultural values, which vary across time and place. Should children be independent or comply? If you live in a Westernized culture, you likely prefer independence. “You are respon- sible for yourself,” Western families and schools tell their children. “Follow your conscience. Be true to yourself. Discover your gifts. Think through your personal needs.” A half - century ago and more, however, Western cultural values placed greater priority on obedience, respect, and sensitivity to others (Alwin, 1990; Remley, 1988). “Be true to your traditions,” parents then taught their children. “Be loyal to your heritage and country. Show respect toward your parents and other superiors.” Cultures can change.

Children across time and place have thrived under various child- rearing systems. Many Americans now give children their own

Cultures vary Parents everywhere care about their children, but raise and protect them differently depending on the surrounding cul- ture. Parents raising children in New York City keep them close. In Scotland’s Orkney Islands’ town of Stromness, social trust has enabled parents to park their toddlers outside shops.

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bedrooms and entrust them to day care. Upper - class British parents tradition- ally handed off routine caregiving to nannies, then sent their 10-year-olds off to boarding school. These children generally grew up to be pillars of British society, as did their parents and their boarding - school peers.

Many Asian and African cultures place less value on independence and more on a strong sense of family self—a feeling that what shames the child shames the family, and what brings honor to the family brings honor to the self. These cultures also value emotional closeness, and infants and toddlers may sleep with their mothers and spend their days close to a family member (Morelli et al., 1992; Whiting & Edwards, 1988). In the African Gusii society, babies nurse freely but spend most of the day on their mother’s back—with lots of body contact but little face - to - face and language interaction. When the mother becomes pregnant again, the toddler is weaned and handed over to someone else, often an older sibling. Westerners may wonder about the negative effects of this lack of verbal interaction, but then the African Gusii may in turn wonder about Western mothers pushing their babies around in strollers and leaving them in playpens (Small, 1997).

Such diversity in child rearing cautions us against presuming that our culture’s way is the only way to rear children successfully. One thing is certain, however: Whatever our culture, the investment in raising a child buys many years not only of joy and love but of worry and irritation. Yet for most people who become parents, a child is one’s biological and social legacy—one’s personal investment in the human future. To para- phrase psychiatrist Carl Jung, we reach backward into our parents and forward into our children, and through their children into a future we will never see, but about which we must therefore care.

RETRIEVE IT

• The three parenting styles have been called “too hard, too soft, and just right.” Which one is “too hard,” which one “too soft,” and which one “just right,” and why?

ANSWER: The authoritarian style would be too hard, the permissive style too soft, and the authoritative style just right. Parents using the authoritative style tend to have children with high self-esteem, self-reliance, and social competence.

Reflections on Nature and Nurture The unique gene combination created when our mother’s egg engulfed our father’s sperm helped form us, as individuals. Genes predispose both our shared humanity and our individual differences.

But it is also true that our experiences form us. In the womb, in our families, and in our peer social relationships, we learn ways of thinking and acting. Even differences initiated by our nature may be amplified by our nurture. We are not formed by either nature or nurture, but by the interaction between them. Biological, psychological, and social-cultural forces interact.

Mindful of how others differ from us, however, we often fail to notice the similari- ties stemming from our shared biology. Regardless of our culture, we humans share the same life cycle. We speak to our infants in similar ways and respond similarly to their coos and cries (Bornstein et al., 1992a,b). All over the world, the children of warm and supportive parents feel better about themselves and are less hostile than are the children of punishing and rejecting parents (Rohner, 1986; Scott et al., 1991). Although Hispanic, Asian, Black, and White Americans differ in school achievement and delinquency, the differences are “no more than skin deep.” To the extent that family structure, peer influ- ences, and parental education predict behavior in one of these ethnic groups, they do so for the others as well. Compared with the person-to-person differences within groups, the differences between groups are small.

Parental involvement promotes development Parents in every culture facilitate their children’s discovery of their world, but cultures differ in what they deem important. Asian cultures place more emphasis on school and hard work than do North Ameri- can cultures. This may help explain why Japa- nese and Taiwanese children get higher scores on mathematics achievement tests.

“You are the bows from which your children as living arrows are sent forth.”

Kahlil Gibran, The Prophet, 1923

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140 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Adolescence 4-11: How is adolescence defined, and how do physical changes affect developing teens?

Many psychologists once believed that childhood sets our traits. Today’s devel- opmental psychologists see development as lifelong. As this life - span perspective emerged, psychologists began to look at how maturation and experience shape us not only in infancy and childhood, but also in adolescence and beyond. Adolescence—the years spent morphing from child to adult—starts with the physical beginnings of sexual matu- rity and ends with the social achievement of independent adult status. In some cultures, where teens are self-supporting, this means that adolescence hardly exists.

G. Stanley Hall (1904), one of the first psychologists to describe adolescence, believed that the tension between biological maturity and social dependence creates a period of “storm and stress.” Indeed, after age 30, many who grow up in independence- fostering Western cul- tures look back on their teenage years as a time they would not want to relive, a time when their peers’ social approval was imperative, their sense of direction in life was in flux, and their feeling of alienation from their parents was deepest (Arnett, 1999; Macfarlane, 1964).

But for many, adolescence is a time of vitality without the cares of adulthood, a time of rewarding friendships, heightened idealism, and a growing sense of life’s exciting possibilities.

Physical Development Adolescence begins with puberty, the time when we mature sexually. Puberty follows a surge of hormones, which may intensify moods and which trigger a series of bodily changes outlined in Chapter 5, Gender and Sexuality.

Just as in the earlier life stages, the sequence of physical changes in puberty (for exam- ple, breast buds and visible pubic hair before menarche—the first menstrual period) is far more predictable than their timing. Some girls start their growth spurt at 9, some boys as late as age 16. Though such variations have little effect on height at maturity, they may have psychological consequences: It is not only when we mature that counts, but how people react to our physical development.

For boys, early maturation has mixed effects. Boys who are stronger and more athletic during their early teen years tend to be more popular, self - assured, and independent, though also more at risk for alcohol use, delinquency, and premature sexual activity (Conley & Rudolph, 2009; Copeland et al., 2010; Lynne et al., 2007). For girls, early maturation can be a challenge (Mendle et al., 2007). If a young girl’s body and hor- mone-fed feelings are out of sync with her emotional maturity and her friends’ physical development and experiences, she may begin associating with older adolescents or may suffer teasing or sexual harassment (Ge & Natsuaki, 2009).

An adolescent’s brain is also a work in progress. Until puberty, brain cells increase their connections, like trees growing more roots and branches. Then, during ado- lescence, comes a selective pruning of unused neurons and connections (Blake- more, 2008). What we don’t use, we lose.

As teens mature, their frontal lobes also continue to develop. The growth of myelin, the fatty tissue that forms around axons and speeds neurotransmission, enables

better communication with other brain regions (Kuhn, 2006; Silveri et al., 2006). These developments bring improved judgment, impulse control, and long-term planning.

Maturation of the frontal lobes nevertheless lags behind that of the emotional limbic system. Puberty’s hormonal surge and limbic system development help explain teens’ occasional impulsiveness, risky behaviors, and emotional storms—slamming doors and turning up the music (Casey et al., 2008). No wonder younger teens (whose unfinished frontal lobes aren’t yet fully equipped for making long - term plans and curbing impulses) so often succumb to the tobacco corporations, which most adult smokers could tell them they will later regret. Teens actually don’t underestimate the risks of smoking—or fast

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At a five - year high school reunion, former best friends may be surprised at their diver- gence; a decade or more later, they may have trouble sustaining a conversation.

How will you look back on your life 10 years from now? Are you making choices that someday you will recollect with satisfaction?

Erik Isakson/JupiterImages

adolescence the transition period from childhood to adulthood, extending from puberty to independence.

puberty the period of sexual maturation, during which a person becomes capable of reproducing.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 141

driving or unprotected sex. They just, when reasoning from their gut, weigh the immedi- ate benefits more heavily (Reyna & Farley, 2006; Steinberg, 2007, 2010). They seek thrills and rewards, but they can’t yet locate the brake pedal controlling their impulses.

So, when Junior drives recklessly and academically self - destructs, should his parents reassure themselves that “he can’t help it; his frontal cortex isn’t yet fully grown”? They can at least take hope: The brain with which Junior begins his teens differs from the brain with which he will end his teens. Unless he slows his brain development with heavy drinking—leaving him prone to impulsivity and addiction—his frontal lobes will continue maturing until about age 25 (Beckman, 2004; Crews et al., 2007).

In 2004, the American Psychological Association joined seven other medical and mental health associations in filing U.S. Supreme Court briefs arguing against the death penalty for 16- and 17-year-olds. The briefs documented the teen brain’s immaturity “in areas that bear upon adolescent decision making.” Teens are “less guilty by reason of adolescence,” suggested psychologist Laurence Steinberg and law professor Elizabeth Scott (2003; Steinberg et al., 2009). In 2005, by a 5-to - 4 margin, the Court concurred, declaring juvenile death penalties unconstitutional.

Cognitive Development

4-12: How did Piaget, Kohlberg, and later researchers describe adolescent cognitive and moral development?

During the early teen years, reasoning is often self - focused. Adolescents may think their private experiences are unique, something parents just could not understand: “But, Mom, you don’t really know how it feels to be in love” (Elkind, 1978). Capable of thinking about their own thinking, and about other people’s thinking, they also begin imagining what others are thinking about them. (They might worry less if they under- stood their peers’ similar self-absorption.) Gradually, though, most begin to reason more abstractly.

Developing Reasoning Power When adolescents achieve the intellectual summit that Jean Piaget called formal opera- tions, they apply their new abstract reasoning tools to the world around them. They may think about what is ideally possible and compare that with the imperfect reality of their society, their parents, and even themselves. They may debate human nature, good and evil, truth and justice. Their sense of what’s fair changes from simple equality—to what’s proportional to merit (Almas et al., 2010). Having left behind the concrete images of early childhood, they may now seek a deeper conception of God and existence (Elkind, 1970; Worthington, 1989). Reasoning hypothetically and deducing consequences also enables adolescents to detect inconsistencies and spot hypocrisy in others’ reasoning, sometimes leading to heated debates with parents and silent vows never to lose sight of their own ideals (Peterson et al., 1986).

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“Young man, go to your room and stay there until your cerebral cortex matures.”

“Ben is in his first year of high school, and he’s questioning all the right things.”

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Demonstrating their reasoning ability Although on opposite sides of the immigration policy debate, these teens are all demonstrat- ing their ability to think logically about abstract topics. According to Piaget, they are in the final cognitive stage, formal operations.

“If a gun is put in the control of the prefrontal cortex of a hurt and vengeful 15-year - old, and it is pointed at a human target, it will very likely go off.”

National Institutes of Health brain scientist Daniel R. Weinberger,

“A Brain Too Young for Good Judgment,” 2001

“When the pilot told us to brace and grab our ankles, the first thing that went through my mind was that we must all look pretty stupid.”

Jeremiah Rawlings, age 12, after a 1989 DC-10 crash in Sioux City, Iowa

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142 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Developing Morality Two crucial tasks of childhood and adolescence are discerning right from wrong and developing character—the psychological muscles for controlling impulses. To be a moral person is to think morally and act accordingly. Jean Piaget and Lawrence Kohlberg proposed that moral reasoning guides moral actions. A more recent view builds on psychology’s game-changing new recognition that much of our functioning occurs not on the “high road” of deliberate, conscious thinking but on the “low road” of unconscious, automatic thinking.

Moral Reasoning Piaget (1932) believed that children’s moral judgments build on their cognitive development. Agreeing with Piaget, Lawrence Kohl- berg (1981, 1984) sought to describe the development of moral reasoning, the thinking that occurs as we consider right and wrong. Kohlberg posed moral dilemmas (for example, whether a person should steal medicine to save a loved one’s life) and asked children, adolescents, and adults whether the action was

right or wrong. His analysis of their answers led him to propose three basic levels of moral thinking: preconventional, conventional, and postconventional (TABLE 4.2). Kohl- berg claimed these levels form a moral ladder. As with all stage theories, the sequence is unvarying. We begin on the bottom rung and ascend to varying heights. Kohlberg’s critics have noted that his postconventional stage is culturally limited, appearing mostly among people who prize individualism (Eckensberger, 1994; Miller & Bersoff, 1995).

Moral Intuition Psychologist Jonathan Haidt (2002, 2006, 2010) believes that much of our morality is rooted in moral intuitions—“quick gut feelings, or affectively laden intu- itions.” In this intuitionist view, the mind makes moral judgments as it makes aesthetic judgments—quickly and automatically. We feel disgust when seeing people engaged in degrading or subhuman acts. Even a disgusting taste in the mouth heightens people’s dis- gust over various moral digressions (Eskine et al., 2011). We feel elevation—a tingly, warm, glowing feeling in the chest—when seeing people display exceptional generosity, compas- sion, or courage. Such feelings in turn trigger moral reasoning, says Haidt.

One woman recalled driving through her snowy neighborhood with three young men as they passed “an elderly woman with a shovel in her driveway. I did not think much of it, when one of the guys in the back asked the driver to let him off there. . . . When I saw him jump out of the back seat and approach the lady, my mouth dropped in shock as I realized that he was offering to shovel her walk for her.” Witnessing this unexpected goodness triggered elevation: “I felt like jumping out of the car and hugging this guy. I felt like singing and running, or skipping and laughing. I felt like saying nice things about people” (Haidt, 2000).

“Could human morality really be run by the moral emotions,” Haidt wonders, “while moral reasoning struts about pretending to be in control?” Consider the desire to pun- ish. Laboratory games reveal that the desire to punish wrongdoings is mostly driven not

Moral reasoning Survivors of the 2010 Haiti earthquake were faced with a moral dilemma: Should they steal household necessi- ties? Their reasoning likely reflected different levels of moral thinking, even if they behaved similarly.

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Kohlberg’s Levels of Moral Thinking

Level (approximate age) Focus Example

Preconventional morality (before age 9)

Self-interest; obey rules to avoid punishment or gain concrete rewards.

“If you save your dying wife, you’ll be a hero.”

Conventional morality (early adolescence)

Uphold laws and rules to gain social approval or maintain social order.

“If you steal the drug for her, everyone will think you’re a criminal.”

Postconventional morality (adolescence and beyond)

Actions reflect belief in basic rights and self-defined ethical principles.

“People have a right to live.”

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 143

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“This might not be ethical. Is that a problem for anybody?”

by reason (such as an objective calculation that punishment deters crime) but rather by emotional reactions, such as moral outrage (Darley, 2009). After the emotional fact, moral reasoning—our mind’s press secretary—aims to convince us and others of the logic of what we have intuitively felt.

This intuitionist perspective on morality finds support in a study of moral paradoxes. Imagine seeing a runaway trolley headed for five people. All will certainly be killed unless you throw a switch that diverts the trolley onto another track, where it will kill one person. Should you throw the switch? Most say Yes. Kill one, save five.

Now imagine the same dilemma, except that your opportunity to save the five requires you to push a large stranger onto the tracks, where he will die as his body stops the trol- ley. Kill one, save five? The logic is the same, but most say No. Seeking to understand why, a Princeton research team led by Joshua Greene (2001) used brain imaging to spy on people’s neural responses as they contemplated such dilemmas. Only when given the body - pushing type of moral dilemma did their brain’s emotion areas activate. Despite the identical logic, the personal dilemma engaged emotions that altered moral judgment.

While the new research illustrates the many ways moral intuitions trump moral reasoning, other research reaffirms the importance of moral reasoning. The religious and moral reasoning of the Amish, for example, shapes their practices of forgiveness, communal life, and modesty (Narvaez, 2010). Joshua Greene (2010) likens our moral cognition to a camera. Usually, we rely on the automatic point-and-shoot mode. But sometimes we use reason to manually override the camera’s automatic impulse.

Moral Action Our moral thinking and feeling surely affect our moral talk. But some- times talk is cheap and emotions are fleeting. Morality involves doing the right thing, and what we do also depends on social influences. As political theorist Hannah Arendt (1963) observed, many Nazi concentration camp guards during World War II were ordi- nary “moral” people who were corrupted by a powerfully evil situation.

Today’s character education programs tend to focus on the whole moral package— thinking, feeling, and doing the right thing. Research has demonstrated that as children’s thinking matures, their behavior also becomes less selfish and more caring (Krebs & Van Hesteren, 1994; Miller et al., 1996). Programs now also teach children empathy for oth- ers’ feelings, and the self - discipline needed to restrain one’s own impulses—to delay small gratifications now to enable bigger rewards later. Those who have learned to delay gratification have become more socially responsible, academically successful, and productive (Funder & Block, 1989; Mischel et al., 1988, 1989). In service-learning programs, where teens have tutored, cleaned up their neighborhoods, and assisted older adults, their sense of competence and desire to serve has increased, and their school absenteeism and drop- out rates have diminished (Andersen, 1998; Piliavin, 2003). Moral action feeds moral attitudes.

RETRIEVE IT

• According to Kohlberg,

morality focuses on upholding laws and social rules,

morality focuses on self-interest, and

morality focuses on self-defined ethical principles.

ANSWERS: conventional; preconventional; postconventional

Social Development

4-13: What are the social tasks and challenges of adolescence?

Theorist Erik Erikson (1963) contended that each stage of life has its own psy- chosocial task, a crisis that needs resolution. Young children wrestle with issues

of trust, then autonomy (independence), then initiative. School - age children strive for competence, feeling able and productive. The adolescent’s task is to synthesize past, present,

“It is a delightful harmony when doing and saying go together.”

Michel Eyquem de Montaigne (1533–1592)

“Somewhere between the ages of 10 and 13 (depending on how hormone- enhanced their beef was), children entered adolescence, a.k.a. ‘the de-cutening.’”

Jon Stewart et al., Earth (The Book), 2010

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144 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

and future possibilities into a clearer sense of self (TABLE 4.3). Adolescents wonder, “Who am I as an individual? What do I want to do with my life? What values should I live by? What do I believe in?” Erikson called this quest the adolescent’s search for identity.

Forming an Identity To refine their sense of identity, adolescents in individualistic cultures usually try out dif- ferent “selves” in different situations. They may act out one self at home, another with friends, and still another at school or on Facebook. If two situations overlap—as when a teenager brings friends home—the discomfort can be considerable. The teen asks, “Which self should I be? Which is the real me?” The resolution is a self - definition that unifies the various selves into a consistent and comfortable sense of who one is—an identity.

For both adolescents and adults, group identities are often formed by how we differ from those around us. When living in Britain, I become conscious of my Americanness. When spending time with my daughter in Africa, I become conscious of my minor- ity White race. When surrounded by women, I am mindful of my gender identity. For international students, for those of a minority ethnic group, for people with a disability, for those on a team, a social identity often forms around their distinctiveness.

Erikson noticed that some adolescents forge their identity early, simply by adopt- ing their parents’ values and expectations. (Traditional, less individualistic cultures teach adolescents who they are, rather than encouraging them to decide on their own.) Other adolescents may adopt the identity of a particular peer group—jocks, preps, geeks, goths.

Most young people do develop a sense of contentment with their lives. When Ameri- can teens were asked whether a series of statements described them, 81 percent said Yes to “I would choose my life the way it is right now.” The other 19 percent agreed that “I wish I were somebody else” (Lyons, 2004). Reflecting on their existence, 75 percent of American collegians say they “discuss religion/spirituality” with friends, “pray,” and agree that “we are all spiritual beings” and “search for meaning/purpose in life” (Astin

Table 4.3

Erikson’s Stages of Psychosocial Development

Stage (approximate age) Issue Description of Task

Infancy (to 1 year)

Trust vs. mistrust

If needs are dependably met, infants develop a sense of basic trust.

Toddlerhood (1 to 3 years)

Autonomy vs. shame and doubt

Toddlers learn to exercise their will and do things for themselves, or they doubt their abilities.

Preschool (3 to 6 years)

Initiative vs. guilt

Preschoolers learn to initiate tasks and carry out plans, or they feel guilty about their efforts to be independent.

Elementary school (6 years to puberty)

Competence vs. inferiority

Children learn the pleasure of applying them- selves to tasks, or they feel inferior.

Adolescence (teen years into 20s)

Identity vs. role confusion

Teenagers work at refining a sense of self by testing roles and then integrating them to form a single identity, or they become confused about who they are.

Young adulthood (20s to early 40s)

Intimacy vs. isolation

Young adults struggle to form close relationships and to gain the capacity for intimate love, or they feel socially isolated.

Middle adulthood (40s to 60s)

Generativity vs. stagnation

In middle age, people discover a sense of con- tributing to the world, usually through family and work, or they may feel a lack of purpose.

Late adulthood (late 60s and up)

Integrity vs. despair

Reflecting on his or her life, an older adult may feel a sense of satisfaction or failure.

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Competence vs. inferiority

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“Self-consciousness, the recognition of a creature by itself as a ‘self,’ [cannot] exist except in contrast with an ‘other,’ a something which is not the self.”

C. S. Lewis, The Problem of Pain, 1940

identity our sense of self; according to Erik- son, the adolescent’s task is to solidify a sense of self by testing and integrating various roles.

social identity the “we” aspect of our self-concept; the part of our answer to “Who am I?” that comes from our group memberships.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 145

et al., 2004; Bryant & Astin, 2008). This would not surprise Stanford psychologist William Damon and his colleagues (2003), who have contended that a key task of adolescence is to achieve a purpose—a desire to accomplish something personally meaningful that makes a difference to the world beyond oneself.

Several nationwide studies indicate that young Ameri- cans’ self- esteem falls during the early to mid - teen years, and, for girls, depression scores often increase. But then self- image rebounds during the late teens and twenties (Erol & Orth, 2011; Robins et al., 2002; Twenge & Nolen- Hoeksema, 2002). Late adolescence is also a time when agreeableness and emotional stability scores increase (Klimstra et al., 2009).

These are the years when many people in industrialized countries begin exploring new opportunities by attending college or working full time. Many college seniors have achieved a clearer identity and a more positive self-concept than they had as first - year students (Waterman, 1988). Collegians who have achieved a clear sense of identity are less prone to alcohol abuse (Bishop et al., 2005).

Erikson contended that adolescent identity formation (which continues into adulthood) is followed in young adulthood by a developing capacity for intimacy, the ability to form emotionally close relationships. Romantic relationships, which tend to be emotionally intense, are reported by some two in three North American 17-year-olds, but fewer among those in collectivist countries such as China (Collins et al., 2009; Li et al., 2010). Those who enjoy high-quality (intimate, supportive) relationships with family and friends tend also to enjoy similarly high-quality romantic relationships in adolescence, which set the stage for healthy adult relationships. Such relationships are, for most of us, a source of great pleasure.

Parent and Peer Relationships

4-14: How do parents and peers influence adolescents?

As adolescents in Western cultures seek to form their own identities, they begin to pull away from their parents (Shanahan et al., 2007). The preschooler

who can’t be close enough to her mother, who loves to touch and cling to her, becomes the 14-year - old who wouldn’t be caught dead holding hands with Mom. The transition occurs gradually (FIGURE 4.18), but this period is typically a time of diminishing paren- tal influence and growing peer influence.

intimacy in Erikson’s theory, the ability to form close, loving relationships; a primary developmental task in late adolescence and early adulthood.

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Who shall I be today? By varying the way they look, adolescents try out different “selves.” Although we eventually form a con- sistent and stable sense of identity, the self we present may change with the situation.

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FIGURE 4.18 The changing parent - child relationship In a large, national study of Canadian families, interviews revealed that the typically close, warm relationships between parents and preschoolers loosened as children became older. (Data from Statistics Canada, 1999.)

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As Aristotle long ago recognized, we humans are “the social animal.” At all ages, but especially during childhood and adolescence, we seek to fit in with our groups and are influenced by them (Harris, 1998, 2000):

• Children who hear English spoken with one accent at home and another in the neighborhood and at school will invariably adopt the accent of their peers, not their parents. Accents (and slang) reflect culture, “and children get their culture from their peers,” noted Judith Rich Harris (2007).

• Teens who start smoking typically have friends who model smoking, suggest its pleasures, and offer cigarettes (J. S. Rose et al., 1999; R. J. Rose et al., 2003). Part of this peer similarity may result from a selection effect, as kids seek out peers with simi- lar attitudes and interests. Those who smoke (or don’t) may select as friends those who also smoke (or don’t).

• When Mihaly Csikszentmihalyi [chick- SENT-me- hi] and Jeremy Hunter (2003) used a beeper to sample the daily experiences of American teens, they found them unhappiest when alone and happiest when with friends.

By adolescence, parent-child arguments occur more often, usually over mundane things—household chores, bedtime, homework (Tesser et al., 1989). Conflict during the transition to adolescence tends to be greater with first-born than with second-born children, and greater with mothers than with fathers (Burk et al., 2009; Shanahan et al., 2007).

For a minority of parents and their adolescents, differences lead to real splits and great stress (Steinberg & Morris, 2001). But most disagreements are at the level of harmless bickering. And most adolescents—6000 of them in 10 countries, from Australia to Ban- gladesh to Turkey—have said they like their parents (Offer et al., 1988). “We usually get along but . . . ,” adolescents often reported (Galambos, 1992; Steinberg, 1987).

Positive parent-teen relations and positive peer relations often go hand in hand. High school girls who had the most affectionate relationships with their mothers tended also to enjoy the most intimate friendships with girlfriends (Gold & Yanof, 1985). And teens who felt close to their parents have tended to be healthy and happy and to do well in school (Resnick et al., 1997). Of course, we can state this correlation the other way: Mis- behaving teens are more likely to have tense relationships with parents and other adults.

Although heredity does much of the heavy lifting in forming individual temperament and personality differences, parents and peers influence teen’s behaviors and attitudes (See Thinking Critically About: How Much Credit or Blame Do Parents Deserve?)

Most teens are herd animals, talking, dressing, and acting more like their peers than their parents. What their friends are, they often become, and what “everybody’s doing,” they often do. In teen calls to hotline counseling services, peer relationships have been the most discussed topic (Boehm et al., 1999). In 2008, according to a Nielsen study, the average American 13- to 17-year-old sent or received more than 1700 text messages a month (Steinhauer & Holson, 2008). Many adolescents become absorbed by social net- working, sometimes with a compulsive use that produces “Facebook fatigue.” Online communication stimulates intimate self-disclosure—both for better (support groups) and for worse (online predators and extremist groups) (Subrahmanyam & Greenfield, 2008; Valkenburg & Peter, 2009).

For those who feel excluded by their peers, the pain is acute. “The social atmosphere in most high schools is poisonously clique - driven and exclusionary,” observed social psychologist Elliot Aronson (2001). Most excluded “students suffer in silence. . . . A small number act out in violent ways against their classmates.” Those who withdraw are vul- nerable to loneliness, low self - esteem, and depression (Steinberg & Morris, 2001). Peer approval matters.

Teens have tended to see their parents as having more influence in other areas—for example, in shaping their religious faith and in thinking about college and career choices (Emerging Trends, 1997). A Gallup Youth Survey revealed that most shared their parent’s political views (Lyons, 2005).

“It’s you who don’t understand me—I’ve been fifteen, but you have never been forty-eight.”

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“I love u guys.”

Emily Keyes’ final text message to her parents before dying in a Colorado

school shooting, 2006

“Men resemble the times more than they resemble their fathers.”

Ancient Arab proverb

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Howard Gardner (1998) has concluded that parents and peers are complementary:

Parents are more important when it comes to education, discipline, responsibility, orderli- ness, charitableness, and ways of interacting with authority figures. Peers are more impor- tant for learning cooperation, for finding the road to popularity, for inventing styles of interaction among people of the same age. Youngsters may find their peers more interesting, but they will look to their par- ents when contemplating their own futures. Moreover, parents [often] choose the neigh- borhoods and schools that supply the peers.

How Much Credit or Blame Do Parents Deserve?

In procreation, a woman and a man shuffle their gene decks and deal a life - forming hand to their child - to - be, who is then subjected to countless influences beyond their control. Par- ents, nonetheless, feel enormous satisfaction in their children’s successes, and feel guilt or shame over their failures. They beam over the child who wins an award. They wonder where they went wrong with the child who is repeat- edly called into the principal’s office. Freudian psychiatry and psychology encouraged such ideas, by blaming problems from asthma to schizophrenia on “bad mothering,” and soci- ety has reinforced parent blaming. Believing that parents shape their offspring as a potter molds clay, people readily praise parents for their children’s virtues and blame them for their children’s vices. Popular culture endlessly pro- claims the psychological harm toxic parents inflict on their fragile children. No wonder hav- ing and raising children can seem so risky.

But do parents really produce future adults with an inner wounded child by being (take your pick from the toxic - parenting lists) overbear- ing—or uninvolved? Pushy—or ineffectual? Overprotective—or distant? Are children really so easily wounded? If so, should we then blame our parents for our failings, and ourselves for our children’s failings? Or does talk of wounding fragile children through normal parental mis- takes trivialize the brutality of real abuse?

Parents do matter. The power of parent- ing is clearest at the extremes: the abused

children who become abusive, the neglected who become neglectful, the loved but firmly handled who become self - confident and socially competent. The power of the family environment also appears in the remarkable academic and vocational successes of children of people who fled from Vietnam and Cambo- dia—successes attributed to close-knit, sup- portive, even demanding families (Caplan et al., 1992).

Yet in personality measures, shared envi- ronmental influences from the womb onward typically account for less than 10 percent of children’s differences. In the words of behavior geneticists Robert Plomin and Denise Daniels (1987; Plomin, 2011), “Two children in the same family are [apart from their shared genes] as different from one another as are pairs of chil- dren selected randomly from the population.”

To developmental psychologist Sandra Scarr (1993), this implied that “parents should be given less credit for kids who turn out great and blamed less for kids who don’t.” Knowing chil- dren are not easily sculpted by parental nurture, perhaps parents can relax a bit more and love their children for who they are.

THINKING CRITICALLY ABOUT:

“To be frank, officer, my parents never set boundaries.”

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“So I blame you for everything—whose fault is that?”

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“If you want to blame your parents for your own adult problems, you are entitled to blame the genes they gave you, but you are not entitled—by any facts I know—to blame the way they treated you. . . . We are not prisoners of our past.”

Martin Seligman, What You Can Change and What You Can’t, 1994

Even among chimpanzees, when one infant is hurt by another, the victim’s mother will often attack the offender’s mother (Goodall, 1968).

Peer power As we develop, we play, mate, and partner with peers. No wonder children and youths are so sensitive and responsive to peer influences.

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This power to select a child’s neighborhood and schools gives parents an ability to influence the culture that shapes the child’s peer group. And because neighborhood influences matter, parents may want to become involved in intervention programs that aim at a whole school or neighborhood. If the vapors of a toxic climate are seeping into a child’s life, that climate—not just the child—needs reforming. Even so, peers are but one medium of cultural influence. As an African proverb declares, “It takes a village to raise a child.”

RETRIEVE IT

• What is the selection effect, and how might it affect a teen’s decision to join sports teams at school?

ANSWER: Adolescents tend to select similar others and to sort themselves into like-minded groups. For an athletic teen, this could lead to finding other athletic teens and joining school teams together.

Emerging Adulthood

4-15: What is emerging adulthood?

In the Western world, adolescence now roughly corresponds to the teen years. At earlier times, and in other parts of the world today, this slice of life has been

much smaller (Baumeister & Tice, 1986). Shortly after sexual maturity, young people would assume adult responsibilities and status. The event might be celebrated with an elaborate initiation—a public rite of passage. The new adult would then work, marry, and have children.

When schooling became compulsory in many Western countries, independence was put on hold until after graduation. From Europe to Australia, adolescents are now tak- ing more time to establish themselves as adults. In the United States, for example, the average age at first marriage has increased more than 4 years since 1960 (to 28 for men, 26 for women). In 1960, three in four women and two in three men had, by age 30, finished school, left home, become financially independent, married, and had a child. Today, fewer than half of 30-year-old women and one-third of men have achieved these five milestones (Henig, 2010).

Delayed independence has overlapped with an earlier onset of puberty. Together, later independence and earlier sexual maturity have widened the once - brief interlude between biological maturity and social independence (FIGURE 4.19). In prosperous communities, the time from 18 to the mid - twenties is an increasingly not - yet - settled

FIGURE 4.19 The transition to adulthood is being stretched from both ends In the 1890s, the average interval between a woman’s first menstrual period and marriage, which typically marked a transition to adulthood, was about 7 years; in industrialized countries today it is about 12 years (Guttmacher, 1994, 2000). Although many adults are unmarried, later marriage combines with prolonged education and earlier menarche to help stretch out the transition to adulthood.

Age

12.5-year interval

10 20 30

Menarche

1995, WOMEN

Marriage

Age

7.2-year interval

10 20 30

Menarche (First period)

1890, WOMEN

Marriage

emerging adulthood for some people in modern cultures, a period from the late teens to mid-twenties, bridging the gap between ado- lescent dependence and full independence and responsible adulthood.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 149

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Stages of the life cycle

phase of life, which some now call emerging adulthood (Arnett, 2006, 2007; Reitzle, 2006). No longer adolescents, these emerging adults, having not yet assumed full adult responsibilities and independence, feel “in between.” After high school, those who enter the job market or go to college may be managing their own time and priorities more than ever before. Yet they may be doing so from their parents’ home—unable to afford their own place and perhaps still emotionally dependent as well. Recognizing today’s more gradually emerging adulthood, the U.S. government now allows dependent children up to age 26 to remain on their parents’ health insur- ance (Cohen, 2010).

RETRIEVE IT

• Match the psychosocial development stage below (1–8) with the issue that Erikson believed we wrestle with at that stage (a–h).

1. Infancy 4. Elementary school 7. Middle adulthood

2. Toddlerhood 5. Adolescence 8. Late adulthood

3. Preschool 6. Young adulthood

a. Generativity vs. stagnation e. Identity vs. role confusion

b. Integrity vs. despair f. Competence vs. inferiority

c. Initiative vs. guilt g. Trust vs. mistrust

d. Intimacy vs. isolation h. Autonomy vs. shame and doubt

ANSWERS: 1. g, 2. h, 3. c, 4. f, 5. e, 6. d, 7. a, 8. b

Reflections on Continuity and Stages Let’s pause now to reflect on the second developmental issue introduced at the beginning of this chapter: continuity and stages. Do adults differ from infants as a giant redwood differs from its seedling—a difference created by gradual, cumulative growth? Or do they differ as a butterfly differs from a caterpillar—a difference of distinct stages?

Generally speaking, researchers who emphasize experience and learning see develop- ment as a slow, continuous shaping process. Those who emphasize biological maturation tend to see development as a sequence of genetically predisposed stages or steps: Although progress through the various stages may be quick or slow, everyone passes through the stages in the same order.

Are there clear - cut stages of psychological development, as there are physical stages such as walking before running? We have considered the stage theories of Jean Piaget on cognitive development, Lawrence Kohlberg on moral development, and Erik Erikson on psychosocial development (sum- marized in FIGURE 4.20 on the next page). And we have seen their stage theories criticized: Young children have some abilities Piaget attributed to later stages. Kohlberg’s work reflected an individualistic worldview and emphasized thinking over feeling and acting. And, as you will see in the next section, adult life does not progress through a fixed, predictable series of steps. Chance events can influence us in ways we would never have predicted.

Although research casts doubt on the idea that life proceeds through neatly defined, age - linked stages, the concept of stage remains useful. The human brain does experience growth spurts during childhood and puberty that correspond roughly to Piaget’s stages (Thatcher et al., 1987). And stage theories contribute a developmental perspective on the whole life span, by suggesting how people of one age think and act differently when they arrive at a later age.

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150 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Jean Piaget

Lawrence Kohlberg

Preconventional morality Conventional morality (Postconventional morality?)

Erik Erikson

Sensorimotor Preoperational Concrete operational

Formal operational

Initiative Competence Identity Intimacy Genera- tivity

Integrity

Birth Death1 2 3 4 5 6 7 8 9 10 11 12 13 14

AutonomyBasic Trust

FIGURE 4.20 Comparing the stage theories (With thanks to Dr. Sandra Gibbs, Muskegon Community College, for inspiring this illustration.)

RETRIEVE IT

• What findings in psychology support the stage theory of development? What findings challenge these ideas?

ANSWERS: Stage theory is supported by the work of Piaget (cognitive development), Kohlberg (moral development), and Erikson (psychosocial development), but it is challenged by findings that change is more gradual and less culturally universal than these theorists supposed.

Adulthood The unfolding of people’s adult lives continues across the life span. It is, however, more difficult to generalize about adulthood stages than about life’s early years. If you know that James is a 1-year- old and Jamal is a 10-year - old, you could say a great deal about each child. Not so with adults who differ by a similar number of years. The boss may be 30 or 60; the marathon runner may be 20 or 50; the 19-year - old may be a parent who supports a child or a child who receives an allowance. Yet our life courses are in some ways similar. Physically, cognitively, and especially socially, we differ at age 50 from our 25-year - old selves. In the discussion that follows, we recognize these differences and use three terms: early adulthood (roughly twenties and thirties), middle adulthood (to age 65), and late adulthood (the years after 65). Within each of these stages, people will vary widely in physical, psychological, and social development.

Physical Development

4-16: What physical changes occur during middle and late adulthood?

Like the declining daylight after the summer solstice, our physical abilities— muscular strength, reaction time, sensory keenness, and cardiac output —all begin an almost imperceptible decline in our mid-twenties. Athletes are often the first to notice. World - class sprinters and swimmers peak by their early twenties. Women—who mature earlier than men—also peak earlier. But most of us—especially those of us whose daily lives do not require top physical performance—hardly perceive the early signs of decline.

Physical Changes in Middle Adulthood Post - 40 athletes know all too well that physical decline gradually accelerates. During early and middle adulthood, physical vigor has less to do with age than with a person’s health and exercise habits. Many of today’s physically fit 50-year - olds run 4 miles with

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menopause the time of natural cessation of menstruation; also refers to the biological changes a woman experiences as her ability to reproduce declines.

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 151

ease, while sedentary 25-year - olds find themselves huff- ing and puffing up two flights of stairs.

Aging also brings a gradual decline in fertility, espe- cially for women. For a 35- to 39-year-old woman, the chances of getting pregnant after a single act of intercourse are only half those of a woman 19 to 26 (Dunson et al., 2002). Men experience a gradual decline in sperm count, testosterone level, and speed of erec- tion and ejaculation. Women experience menopause, as menstrual cycles end, usually within a few years of age 50. Expectations and attitudes influence the emotional impact of this event. Is it a sign of lost femininity and growing old? Or is it liberation from menstrual periods and fears of pregnancy? For men, too, expectations can influence perceptions. Some experience distress related to a perception of declining virility and physical capaci- ties, but most age without such problems.

With age, sexual activity lessens. Nevertheless, most men and women remain capable of satisfying sexual activity, and most express satisfaction with their sex life. This was true of 70 percent of Canadians surveyed (ages 40 to 64) and 75 percent of Finns (ages 65 to 74) (Kontula & Haavio-Mannila, 2009; Wright, 2006). In another survey, 75 percent of respondents reported being sexually active into their eighties (Schick et al., 2010). And in an Ameri- can Association of Retired Persons sexuality survey, it was not until age 75 or older that most women and nearly half of men reported little sexual desire (DeLamater & Sill, 2005). Given good health and a willing partner, the flames of desire, though simmered down, live on. As Alex Comfort (1992, p. 240) jested, “The things that stop you having sex with age are exactly the same as those that stop you riding a bicycle (bad health, thinking it looks silly, no bicycle).”

Physical Changes in Later Life Is old age “more to be feared than death” (Juvenal, Satires)? Or is life “most delightful when it is on the downward slope” (Seneca, Epistulae ad Lucilium)? What is it like to grow old?

Strength and Stamina Although physical decline begins in early adulthood, we are not usually acutely aware of it until later life, when the stairs get steeper, the print gets smaller, and other people seem to mumble more. Muscle strength, reaction time, and stamina diminish in late adulthood. As a lifelong basketball player, I find myself increas- ingly not racing for that loose ball. But even diminished vigor is sufficient for normal activities. Moreover, exercise slows aging. Active older adults tend to be mentally quick older adults. Physical exercise not only enhances muscles, bones, and energy and helps to prevent obesity and heart disease, it also stimulates brain cell development and neural connections, thanks perhaps to increased oxygen and nutrient flow (Erickson et al., 2010; Pereira et al., 2007).

Sensory Abilities With age, visual sharpness diminishes, and distance perception and adaptation to light-level changes are less acute. The eye’s pupil shrinks and its lens becomes less transparent, reducing the amount of light reaching the retina: A 65-year- old retina receives only about one- third as much light as its 20-year - old counterpart (Kline & Schieber, 1985). Thus, to see as well as a 20-year - old when reading or driving, a 65-year - old needs three times as much light—a reason for buying cars with untinted windshields. This also explains why older people sometimes ask younger people, “Don’t you need better light for reading?”

Adult abilities vary widely 97-year- olds: Don’t try this. In 2002, George Blair became the world’s oldest bare- foot water skier, just days after reaching age 87. And he did it again in 2012, at age 97!

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“Happy fortieth. I’ll take the muscle tone in your upper arms, the girlish timbre of your voice, your amazing tolerance for caffeine, and your ability to

digest french fries. The rest of you can stay.”

“For some reason, possibly to save ink, the restaurants had started printing their menus in letters the height of bacteria.”

Dave Barry, Dave Barry Turns Fifty, 1998

Most stairway falls taken by older people occur on the top step, precisely where the person typically descends from a window - lit hallway into the darker stairwell (Fozard & Popkin, 1978). Our knowledge of aging could be used to design environments that would reduce such accidents (National Research Council, 1990).

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152 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

The senses of smell and hearing also diminish. In Wales, teens’ loitering around a con- venience store has been discouraged by a device that emits an aversive high-pitched sound almost no one over 30 can hear (Lyall, 2005). Some students have also used that pitch to their advantage with cell-phone ringtones their instructors cannot hear (Vitello, 2006).

Health For those growing older, there is both bad and good news about health. The bad news: The body’s disease - fighting immune system weakens, making older adults more susceptible to life - threatening ailments, such as cancer and pneumonia. The good news: Thanks partly to a lifetime’s accumulation of antibodies, people over 65 suffer fewer short-term ailments, such as common flu and cold viruses. One study found they were half as likely as 20-year - olds and one - fifth as likely as preschoolers to suffer upper respiratory flu each year (National Center for Health Statistics, 1990).

The Aging Brain Up to the teen years, we process information with greater and greater speed (Fry & Hale, 1996; Kail, 1991). But compared with teens and young adults, older people take a bit more time to react, to solve perceptual puzzles, even to remember names (Bashore et al., 1997; Verhaeghen & Salthouse, 1997). The neural processing lag is greatest on complex tasks (Cerella, 1985; Poon, 1987). At video games, most 70-year - olds are no match for a 20-year - old.

Slower neural processing combined with diminished sensory abilities can increase acci- dent risks. As FIGURE 4.21 indicates, fatal accident rates per mile driven increase sharply after age 75. By age 85, they exceed the 16-year - old level. Nevertheless, because older people drive less, they account for fewer than 10 percent of crashes (Coughlin et al., 2004).

Brain regions important to memory begin to atrophy during aging (Schacter, 1996). In young adulthood, a small, gradual net loss of brain cells begins, contributing by age 80 to a brain - weight reduction of 5 percent or so. Earlier, we noted that late-maturing frontal lobes help account for teen impulsivity. Late in life, atrophy of the inhibition- controlling frontal lobes seemingly explains older people’s occasional blunt questions and comments (“Have you put on weight?”) (von Hippel, 2007).

As noted earlier, exercise helps counteract some effects of brain aging. It aids memory by stimulating the development of neural connections and by promoting neurogenesis, the birth of new nerve cells, in the hippocampus. Sedentary older adults randomly assigned to aerobic exercise programs exhibit enhanced memory, sharpened judgment, and reduced risk of dementia (Colcombe et al., 2004; Liang et al., 2010; Nazimek, 2009).

Exercise also helps maintain the telomeres, which protect the ends of chromosomes (Cherkas et al., 2008; Erickson, 2009; Pereira et al., 2007). With age, telomeres wear down, much as the tip of a shoelace frays. This wear is accentuated by smoking, obesity, or stress. As telomeres shorten, aging cells may die without being replaced with perfect genetic replicas (Epel, 2009).

The message for seniors is clear: We are more likely to rust from disuse than to wear out from overuse.

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Fatal accident

rate

16–19 20–24 25–29 30–34 35–39 40–44 45–49 50–54 55–59 60–64 65–69 70–74

Age in years

75 and over

Fatal accidents per 100 million milesFatal accidents

per 10,000 drivers

The fatal accident rate jumps over age 65, especially when measured per miles driven

FIGURE 4.21 Age and driver fatalities Slowing reactions contribute to increased accident risks among those 75 and older, and their greater fragility increases their risk of death when accidents happen (NHTSA, 2000). Would you favor driver exams based on performance, not age, to screen out those whose slow reactions or sensory impairments indicate accident risk?

cross - sectional study a study in which people of different ages are compared with one another.

longitudinal study research in which the same people are restudied and retested over a long period.

How old does a person have to be before you think of him or her as old? Depends on who you ask. For 18- to 29-year - olds, 67 was old. For those 60 and over, old was 76 (Yankelovich, 1995).

“I am still learning.”

Michelangelo, 1560, at age 85

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 153

Cognitive Development

4-17: How does memory change with age?

Among the most intriguing developmental psychology questions is whether adult cognitive abilities, such as memory, intelligence, and creativity, parallel

the gradually accelerating decline of physical abilities. As we age, we remember some things well. Looking back in later life,

people asked to recall the one or two most important events over the last half - century tend to name events from their teens or twenties (Conway et al., 2005; Rubin et al., 1998). Whatever people experience around this time of life—the events of 9/11, the civil rights movement, World War II—becomes pivotal (Pillemer, 1998; Schuman & Scott, 1989). Our teens and twenties are a time of so many memorable “firsts”—first date, first job, first day at college or university, first meeting of in - laws.

Early adulthood is indeed a peak time for some types of learning and remember- ing. In one test of recall, people (1205 of them) watched videotapes as 14 strangers said their names, using a common format: “Hi, I’m Larry” (Crook & West, 1990). Then those strangers reappeared and gave additional details. For example, saying “I’m from Phila- delphia” provided visual and voice cues for remembering the person’s name. As FIGURE 4.22 shows, after a second and third replay of the introductions, everyone remembered more names, but younger adults consistently surpassed older adults.

Perhaps it is not surprising, then, that nearly two - thirds of people over age 40 say their memory is worse than it was 10 years ago (KRC, 2001). In fact, how well older people remember depends on the task. In another experiment (Schonfield & Robert- son, 1966), when asked to recognize 24 words they had earlier tried to memorize, people showed only a minimal decline in memory. When asked to recall that information with- out clues, the decline was greater (FIGURE 4.23).

In our capacity to learn and remember, as in other areas of development, we dif- fer. Younger adults vary in their abilities to learn and remember, but 70-year - olds vary much more. “Differences between the most and least able 70-year-olds become much greater than between the most and least able 50-year-olds,” reports Oxford researcher Patrick Rabbitt (2006). Some 70-year - olds perform below nearly all 20-year - olds; other 70-year- olds match or outdo the average 20-year - old.

No matter how quick or slow we are, remembering seems also to depend on the type of information we are trying to retrieve. If the information is meaningless—nonsense syllables or unimportant events—then the older we are, the more errors we are likely to make. If the information is meaningful, older people’s rich web of existing knowledge will help them to hold it. But they may take longer than younger adults to produce the words and things they know: Quick - thinking game show winners are usually young or middle - aged adults (Burke & Shafto, 2004). Older people’s capacity to learn and remember skills declines less than their verbal recall (Graf, 1990; Labouvie- Vief & Schell, 1982; Perlmutter, 1983).

Chapter 9, Thinking, Language, and Intelligence, explores another dimension of cognitive development: intelligence. As we will see, cross-sectional studies (comparing people of different ages) and longitudinal studies (restudying people over time) have identified mental abilities that do and do not change as people age. Age is less a predictor of memory and intelligence than is proximity to death. Tell me whether someone is 8 months or 8 years from death and, regardless of age, you’ve given me a clue to that person’s mental ability. Especially in the last three or four years of life, cognitive decline typically accelerates (Wilson et al., 2007). Researchers call this near-death drop terminal decline (Backman & MacDonald, 2006).

60

70

80

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30

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recalled

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After two introductions

After one introduction

After three introductions

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Number of words

remembered

Age in years 20 30 40 706050

Number of words recognized is stable with age

Number of words recalled declines with age

Age group

FIGURE 4.22 Tests of recall Recalling new names introduced once, twice, or three times is easier for younger adults than for older ones. (Data from Crook & West, 1990.)

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FIGURE 4.23 Recall and recognition in adulthood In this experiment, the ability to recall new information declined during early and middle adulthood, but the ability to recognize new information did not. (From Schonfield & Robertson, 1966.)

If you are within 5 years of 20, what experiences from the past year will you likely never forget? (This is the time of your life you may best remember when you are 50.)

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154 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Social Development

4-18: What themes and influences mark our social journey from early adulthood to death?

Many differences between younger and older adults are created by significant life events. A new job means new relationships, new expectations, and new demands. Marriage brings the joy of intimacy and the stress of merging two lives. The three years surrounding the birth of a child bring increased life satisfaction for most parents (Dyrdal & Lucas, 2011). The death of a loved one creates an irreplaceable loss. Do these adult life events shape a sequence of life changes?

Adulthood’s Ages and Stages As people enter their forties, they undergo a transition to middle adulthood, a time when they realize that life will soon be mostly behind instead of ahead of them. Some psychologists have argued that for many the midlife transition is a crisis, a time of great struggle, regret, or even feeling struck down by life. The popular image of the midlife crisis is an early - forties man who forsakes his family for a younger girlfriend and a hot sports car. But the fact—reported by large samples of people—is that unhappiness, job dissatisfaction, marital dissatisfaction, divorce, anxiety, and suicide do not surge dur- ing the early forties (Hunter & Sundel, 1989; Mroczek & Kolarz, 1998). Divorce, for example, is most common among those in their twenties, suicide among those in their seventies and eighties. One study of emotional instability in nearly 10,000 men and women found “not the slightest evidence” that distress peaks anywhere in the midlife age range (McCrae & Costa, 1990).

For the 1 in 4 adults who report experiencing a life crisis, the trigger is not age but a major event, such as illness, divorce, or job loss (Lachman, 2004). Some middle-aged adults describe themselves as a “sandwich generation,” simultaneously supporting their aging parents and their emerging adult children or grandchildren (Riley & Bowen, 2005).

Life events trigger transitions to new life stages at varying ages. The social clock— the definition of “the right time” to leave home, get a job, marry, have children, or retire—varies from era to era and culture to culture. The once-rigid sequence for many Western women—of student to worker to wife to at - home mom to worker again—has loosened. Contemporary women occupy these roles in any order or all at once. The social clock still ticks, but people feel freer about being out of sync with it.

Even chance events can have lasting significance, by deflecting us down one road rather than another (Bandura, 1982). Albert Bandura (2005) recalls the ironic true story of a book editor who came to one of Bandura’s lectures on the “Psychology of Chance Encounters and Life Paths”—and ended up marrying the woman who happened to sit next to him. The sequence that led to my authoring this book (which was not my idea) began with my being seated near, and getting to know, a distinguished colleague at an international conference. Chance events can change our lives.

Adulthood’s Commitments Two basic aspects of our lives dominate adulthood. Erik Erikson called them intimacy (forming close relationships) and generativity (being produc- tive and supporting future generations). Researchers have chosen various terms—affiliation and achievement, attachment and productivity, connectedness and competence. Sigmund Freud (1935) put it most simply: The healthy adult, he said, is one who can love and work.

Love We typically flirt, fall in love, and commit—one person at a time. “Pair - bonding is a trademark of the human animal,” observed anthro- pologist Helen Fisher (1993). From an evolutionary perspective, relatively monogamous pairing makes sense: Parents who cooperated to nurture

social clock the culturally preferred timing of social events such as marriage, parenthood, and retirement.

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“Midway in the journey of our life I found myself in a dark wood, for the straight way was lost.”

Dante, The Divine Comedy, 1314

“The important events of a person’s life are the products of chains of highly improbable occurrences.”

Joseph Traub, “Traub’s Law,” 2003

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 155

their children to maturity were more likely to have their genes passed along to posterity than were parents who didn’t.

Adult bonds of love are most satisfying and enduring when marked by a similarity of interests and values, a sharing of emotional and material support, and intimate self- disclosure (see Chapter 13). Couples who seal their love with commitment—via (in one Vermont study) marriage for heterosexual couples and civil unions for homosexual couples—more often endure (Balsam et al., 2008). Marriage bonds are especially likely to last when couples marry after age 20 and are well educated. Compared with their counterparts of 50 years ago, people in Western countries are better educated and marrying later. Yet, ironically, they are nearly twice as likely to divorce. (Both Canada and the United States now have about one divorce for every two marriages, and in Europe, divorce is only slightly less common.) The divorce rate partly reflects women’s lessened economic dependence and men’s and women’s rising expectations. We now hope not only for an enduring bond, but also for a mate who is a wage earner, caregiver, intimate friend, and warm and responsive lover.

Might test driving life together in a “trial marriage” minimize divorce risk? In one Gallup survey of American twenty - somethings, 62 percent thought it would (White- head & Popenoe, 2001). In reality, in Europe, Canada, and the United States, those who cohabit before marriage have had higher rates of divorce and marital dysfunction than those who did not cohabit (Jose et al., 2009). The risk appears greatest for those cohabit- ing prior to engagement (Goodwin et al., 2010; Rhoades et al., 2009).

American children born to cohabiting parents are about five times more likely to expe- rience their parents’ separation than are children born to married parents (Osborne et al., 2007). Two factors contribute. First, cohabiters tend to be initially less committed to the ideal of enduring marriage. Second, they become even less marriage supporting while cohabiting.

Nonetheless, the institution of marriage endures. Worldwide, reports the United Nations, 9 in 10 heterosexual adults marry. And marriage is a predictor of happiness, sexual satisfaction, income, and physical and mental health (Scott et al., 2010). National Opinion Research Center surveys of nearly 50,000 Americans since 1972 reveal that 40 percent of married adults, though only 23 percent of unmarried adults, have reported being “very happy.” Lesbian couples, too, report greater well- being than those who are alone (Peplau & Fingerhut, 2007; Wayment & Peplau, 1995). Moreover, neighborhoods with high marriage rates typically have low rates of social pathologies such as crime, delinquency, and emotional disorders among children (Myers & Scanzoni, 2005).

Marriages that last are not always devoid of conflict. Some couples fight but also shower each other with affection. Other couples never raise their voices yet also sel- dom praise each other or nuzzle. Both styles can last. After observing the interactions of 2000 couples, John Gottman (1994) reported one indicator of marital success: at least a five- to- one ratio of positive to negative interactions. Stable marriages provide five times more instances of smiling, touching, complimenting, and laughing than of sarcasm, criti- cism, and insults. So, if you want to predict which newlyweds will stay together, don’t pay attention to how passionately they are in love. The couples who make it are more often those who refrain from putting down their partners. To prevent a cancerous nega- tivity, successful couples learn to fight fair (to state feelings without insulting) and to steer conflict away from chaos with comments like “I know it’s not your fault” or “I’ll just be quiet for a moment and listen.”

Often, love bears children. For most people, this most enduring of life changes is a happy event. “I feel an overwhelming love for my children unlike anything I feel for anyone else,” said 93 percent of American mothers in a national survey (Erickson & Aird, 2005). Many fathers feel the same. A few weeks after the birth of my first child I was suddenly struck by a realization: “So this is how my parents felt about me?”

When children begin to absorb time, money, and emotional energy, satisfaction with the marriage itself may decline (Doss et al., 2009). This is especially likely among employed women who, more than they expected, carry the traditional burden of doing the chores at home. Putting effort into creating an equitable relationship can thus pay double dividends: a more satisfying marriage, which breeds better parent- child relations (Erel & Burman, 1995).

Love Intimacy, attachment, commitment— love by whatever name—is central to healthy and happy adulthood.

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What do you think? Does marriage correlate with happiness because marital support and intimacy breed happiness, because happy people more often marry and stay married, or both?

“Our love for children is so unlike any other human emotion. I fell in love with my babies so quickly and profoundly, almost completely independently of their particular qualities. And yet 20 years later I was (more or less) happy to see them go—I had to be happy to see them go. We are totally devoted to them when they are little and yet the most we can expect in return when they grow up is that they regard us with bemused and tolerant affection.”

Developmental psychologist Alison Gopnik, “The Supreme Infant,” 2010

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Although love bears children, children eventually leave home. This departure is a significant and sometimes difficult event. For most people, however, an empty nest is a happy place (Adelmann et al., 1989; Gorchoff et al., 2008). Many parents experience a “postlaunch honeymoon,” especially if they maintain close relationships with their children (White & Edwards, 1990). As Daniel Gilbert (2006) has said, “The only known symptom of ‘empty nest syndrome’ is increased smiling.”

Work For many adults, the answer to “Who are you?” depends a great deal on the answer to “What do you do?” For women and men, choosing a career path is difficult, especially during bad economic times. Even in the best of times, few students in their first two years of college or university can predict their later careers.

In the end, happiness is about having work that fits your interests and provides you with a sense of competence and accomplishment. It is having a close, supportive com- panion who cheers your accomplishments (Gable et al., 2006). And for some, it includes having children who love you and whom you love and feel proud of.

RETRIEVE IT

• Freud defined the healthy adult as one who is able to

and to .

ANSWERS: love; work

Well - Being Across the Life Span

4-19: Do self-confidence and life satisfaction vary with life stages?

To live is to grow older. This moment marks the oldest you have ever been and the youngest you will henceforth be. That means we all can look back

with satisfaction or regret, and forward with hope or dread. When asked what they would have done differently if they could relive their lives, people’s most common answer has been “Taken my education more seriously and worked harder at it” (Kinnier & Metha, 1989; Roese & Summerville, 2005). Other regrets—“I should have told my father I loved him,” “I regret that I never went to Europe”—have also focused less on mistakes made than on the things one failed to do (Gilovich & Medvec, 1995).

From the teens to midlife, people typically experience a strengthening sense of iden- tity, confidence, and self - esteem (Huang, 2010; Robins & Trzesniewski, 2005). In later life, challenges arise: Income shrinks. Work is often taken away. The body deteriorates. Recall fades. Energy wanes. Family members and friends die or move away. The great enemy, death, looms ever closer. And for those in the terminal decline phase, life satisfac- tion does decline as death approaches (Gerstorf et al., 2008).

Small wonder that most presume that happiness declines in later life (Lacey et al., 2006). But worldwide, as Gallup researchers discovered, most find that the over- 65 years are not notably unhappy (FIGURE 4.24). If anything, positive feelings, supported

by enhanced emotional control, grow after midlife and nega- tive feelings subside (Stone et al., 2010; Urry & Gross, 2010). Older adults increasingly use words that convey positive emo- tions (Pennebaker & Stone, 2003), and they attend less and less to negative information. Compared with younger adults, for example, they are slower to perceive negative faces and more attentive to positive news (Carstensen & Mikels, 2005; Scheibe & Carstensen, 2010). Older adults also have fewer problems in their social relationships (Fingerman & Charles, 2010), and they expe- rience less intense anger, stress, and worry (Stone et al., 2010).

The aging brain may help nurture these positive feelings. Brain scans of older adults show that the amygdala, a neural processing center for emotions, responds less actively to negative events (but

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Best life

Worst life

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18–29

Age 30–39 40–49 50–59 70+60–69

If you have left home, did your parents suffer the “empty nest syndrome”—a feeling of distress focusing on a loss of purpose and relationship? Did they mourn the lost joy of listening for you in the wee hours of Saturday morning? Or did they seem to discover a new freedom, relaxation, and (if together) renewed satisfaction with their own relationship?

“When you were born, you cried and the world rejoiced. Live your life in a manner so that when you die the world cries and you rejoice.”

Native American proverb

10Best life

FIGURE 4.24 Age and life satisfaction The Gallup Organization asked 142,682 people worldwide to rate their lives on a ladder, from 0 (“the worst possible life”) to 10 (“the best possible life”). Age gave no clue to life satisfaction (Crabtree, 2010).

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 157

not to positive events), and it interacts less with the hippocampus, a brain memory-process- ing center (Mather et al., 2004; St. Jacques et al., 2009; Williams et al., 2006). Brain-wave reactions to negative images also diminish with age (Kisley et al., 2007).

Moreover, at all ages, the bad feelings we associate with negative events fade faster than do the good feelings we associate with positive events (Walker et al., 2003). This contributes to most older people’s sense that life, on balance, has been mostly good. Given that growing older is an outcome of living (an outcome most prefer to early dying), the positivity of later life is comforting. Thanks to biological, psychological, and social-cultural influences, more and more people flourish into later life (FIGURE 4.25).

“At 20 we worry about what others think of us. At 40 we don’t care what others think of us. At 60 we discover they haven’t been thinking about us at all.”

Anonymous

Biological influences: • no genes predisposing dementia or other diseases • appropriate nutrition

Psychological influences: • optimistic outlook • physically and mentally active lifestyle

Social-cultural influences: • support from family and friends • cultural respect for aging • safe living conditions

Successful aging

FIGURE 4.25 Biopsychosocial influences on successful aging Numerous biological, psychological, and social- cultural factors affect the way we age. With the right genes, we have a good chance of aging successfully if we maintain a positive outlook and stay mentally and physically active as well as connected to family and friends in the community.

“The best thing about being 100 is no peer pressure.”

Lewis W. Kuester, 2005, on turning 100

RETRIEVE IT

• What are some of the most significant challenges and rewards of growing old?

ANSWERS: Challenges: decline of muscular strength, reaction times, stamina, sensory keenness, cardiac output, and immune system functioning. Rewards: positive feelings tend to grow, negative emotions are less intense, and anger, stress, worry, and social-relationship problems decrease.

Death and Dying

4-20: A loved one’s death triggers what range of reactions?

Warning: If you begin reading the next paragraph, you will die. But of course, if you hadn’t read this, you would still die in due time. Death

is our inevitable end. Most of us will also suffer and cope with the deaths of relatives and friends. Usually, the most difficult separation is from a spouse—a loss suffered by five times more women than men. When, as usually happens, death comes at an expected late - life time, grieving may be relatively short - lived.

Grief is especially severe when a loved one’s death comes suddenly and before its expected time on the social clock. The sudden illness or accident claiming a 45-year- old life partner or a child may trigger a year or more of memory-laden mourning that eventually subsides to a mild depression (Lehman et al., 1987).

For some, however, the loss is unbearable. One Danish long-term study of more than 1 million people found that about 17,000 of them had suffered the death of a child under 18. In the five years following that death, 3 percent of them had a first psychiatric hospitalization. This rate was 67 percent higher than the rate recorded for parents who had not lost a child (Li et al., 2005).

“Love—why, I’ll tell you what love is: It’s you at 75 and her at 71, each of you listening for the other’s step in the next room, each afraid that a sudden silence, a sudden cry, could mean a lifetime’s talk is over.”

Brian Moore, The Luck of Ginger Coffey, 1960

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158 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN ©

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Even so, reactions to a loved one’s death range more widely than most suppose. Some cultures encourage public weeping and wailing; others hide grief. Within any culture, individuals differ. Given similar losses, some people grieve hard and long, others less so (Ott et al., 2007). Contrary to popular misconceptions, however,

• terminally ill and bereaved people do not go through identical predictable stages, such as denial before anger (Friedman & James, 2008; Nolen - Hoeksema & Larson, 1999). A Yale study following 233 bereaved individuals through time did, however, find that yearning for the loved one reached a high point four months after the loss, with anger peaking, on average, about a month later (Maciejewski et al., 2007).

• those who express the strongest grief immediately do not purge their grief more quickly (Bonanno & Kaltman, 1999; Wortman & Silver, 1989).

• bereavement therapy and self - help groups offer support, but there is similar healing power in the passing of time, the support of friends, and the act of giving support and help to others (Baddeley & Singer, 2009; Brown et al., 2008; Neimeyer & Carrier, 2009). Grieving spouses who talk often with others or receive grief counseling adjust about as well as those who grieve more privately (Bonanno, 2004; Stroebe et al., 2005). We can be grateful for the waning of death - denying attitudes. Facing death with dig-

nity and openness helps people complete the life cycle with a sense of life’s meaningful- ness and unity—the sense that their existence has been good and that life and death are parts of an ongoing cycle. Although death may be unwelcome, life itself can be affirmed even at death. This is especially so for people who review their lives not with despair but with what Erik Erikson called a sense of integrity—a feeling that one’s life has been meaningful and worthwhile.

Reflections on Stability and Change It’s time to reflect on the third big developmental issue: As we follow lives through time, do we find more evidence for stability or change? If reunited with a long - lost grade- school friend, do we instantly realize that “it’s the same old Andy”? Or do people we befriend during one period of life seem like strangers at a later period? (At least one acquaintance of mine would choose the second option. He failed to recognize a former classmate at his 40-year college reunion. The aghast classmate eventually pointed out that she was his long-ago first wife.)

Research reveals that we experience both stability and change. As we have seen, some of our characteristics, such as temperament, are very stable:

• One study followed 1000 New Zealanders through time, beginning at age 3. Those who had scored low in conscientiousness and self-control as preschoolers were more vulnerable to ill health, substance abuse, arrest, and single parenthood as 32-year-olds (Moffitt et al., 2011).

• Another research team interviewed adults who, 40 years earlier, had their talkative- ness, impulsiveness, and humility rated by their elementary school teachers (Nave et al., 2010). To a striking extent, their traits persisted.

“As at 7, so at 70,” says a Jewish proverb. The widest smilers in childhood and college photos are, years later, the ones most likely to enjoy enduring marriages (Hertenstein et al., 2009). While 1 in 4 of the weakest college smilers eventually divorced, only 1 in 20 of the widest smilers did so. As people grow older, personality gradually stabilizes (Fer- guson, 2010; Hopwood et al., 2011; Kandler et al., 2010). The struggles of the present may be laying a foundation for a happier tomorrow.

We cannot, however, predict all of our eventual traits based on our early years of life (Kagan et al., 1978, 1998). Some traits, such as social attitudes, are much less stable than temperament (Moss & Susman, 1980). Older children and adolescents learn new ways of coping. Although delinquent children have elevated rates of later work problems, substance abuse, and crime, many confused and troubled children blossom into mature,

“At 70, I would say the advantage is that you take life more calmly. You know that ‘this, too, shall pass’!”

Eleanor Roosevelt, 1954

“Consider, friend, as you pass by, as you are now, so once was I. As I am now, you too shall be. Prepare, therefore, to follow me.”

Scottish tombstone epitaph

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 159

successful adults (Moffitt et al., 2002; Roberts et al., 2001; Thomas & Chess, 1986). Happily for them, life is a process of becoming.

In some ways, we all change with age. Most shy, fearful toddlers begin opening up by age 4, and most people become more conscientious, stable, agreeable, and self- confident in the years after adolescence (Lucas & Donnellan, 2009; Roberts et al., 2003, 2006, 2008; Shaw et al., 2010). Many irresponsible 18-year- olds have matured into 40-year - old business or cultural leaders. (If you are the former, you aren’t done yet.) Such changes can occur without changing a person’s position relative to others of the same age. The hard - driving young adult may mellow by later life, yet still be a relatively driven senior citizen.

Life requires both stability and change. Stability provides our iden- tity. It enables us to depend on others and be concerned about the healthy development of the children in our lives. Our trust in our ability to change gives us our hope for a brighter future. It motivates our concerns about present influences and lets us adapt and grow with experience.

RETRIEVE IT

• What findings in psychology support the idea of stability in personality across the life span? What findings challenge these ideas?

ANSWER: Some traits, such as temperament, do exhibit remarkable stability across many years. But we do change in other ways, such as in our social attitudes, especially during life’s early years.

Smiles predict marital stability In one study of 306 college alums, 1 in 4 with yearbook expressions like the one on the left later divorced, as did only 1 in 20 with smiles like the one on the right (Hertenstein et al., 2009).

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CHAPTER REVIEW

Developing Through the Life Span

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the chapter). Then turn to Appendix D, Complete Chapter Reviews, to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

Developmental Psychology’s Major Issues 4-1: What three issues have engaged developmental

psychologists?

Prenatal Development and the Newborn 4–2: What is the course of prenatal development, and

how do teratogens affect that development?

4–3: What are some newborn abilities, and how do researchers explore infants’ mental abilities?

Infancy and Childhood 4–4: During infancy and childhood, how do the brain

and motor skills develop?

4–5: From the perspectives of Piaget, Vygotsky, and today’s researchers, how does a child’s mind develop?

4–6: How do parent-infant attachment bonds form?

4–7: How have psychologists studied attachment differences, and what have they learned?

4–8: How does childhood neglect or abuse affect children’s attachments?

4–9: How does day care affect children?

4–10: What are three parenting styles, and how do children’s traits relate to them?

LEARNING OBJECTIVES

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160 CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN

Adulthood 4–16: What physical changes occur during middle and

late adulthood?

4–17: How does memory change with age?

4–18: What themes and influences mark our social journey from early adulthood to death?

4–19: Do self-confidence and life satisfaction vary with life stages?

4–20: A loved one’s death triggers what range of reactions?

Test yourself on these terms by trying to write down the definition in your own words before flip- ping back to the referenced page to check your answer.

developmental psychology, p. 118

zygote, p. 119

embryo, p. 119

fetus, p. 119

teratogens, p. 120

fetal alcohol syndrome (FAS), p. 120

habituation, p. 121

maturation, p. 121

critical period, p. 123

cognition, p. 124

schema, p. 125

assimilation, p. 125

accommodation, p. 125

sensorimotor stage, p. 126

object permanence, p. 126

preoperational stage, p. 127

conservation, p. 127

egocentrism, p. 128

theory of mind, p. 128

concrete operational stage, p. 128

formal operational stage, p. 129

autism, p. 130

stranger anxiety, p. 132

attachment, p. 132

imprinting, p. 133

temperament, p. 134

basic trust, p. 135

adolescence, p. 140

puberty, p. 140

identity, p. 144

social identity, p. 144

intimacy, p. 145

emerging adulthood, p. 149

menopause, p. 151

cross-sectional study, p. 153

longitudinal study, p. 153

social clock, p. 154

TERMS AND CONCEPTS TO REMEMBER

Adolescence 4–11: How is adolescence defined, and how do physical

changes affect developing teens?

4–12: How did Piaget, Kohlberg, and later researchers describe adolescent cognitive and moral development?

4–13: What are the social tasks and challenges of adolescence?

4–14: How do parents and peers influence adolescents?

4–15: What is emerging adulthood?

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

1. The three major issues that interest developmental psy- chologists are nature/nurture, stability/change, and / .

2. Body organs first begin to form and function during the period of the ; within 6 months, during the period of the , the organs are suffi- ciently functional to allow a chance of survival.

a. zygote; embryo b. zygote; fetus c. embryo; fetus d. placenta; fetus

3. Chemicals that pass through the placenta’s screen and may harm an embryo or fetus are called .

4. Stroke a newborn’s cheek and the infant will root for a nipple. This illustrates

a. a reflex. b. nurture. c. differentiation. d. continuity.

5. Between ages 3 and 6, the human brain experiences the greatest growth in the lobes, which we use for rational planning, and which continue developing at least into adolescence.

6. Which of the following is true of motor-skill development? a. It is determined solely by genetic factors. b. The sequence, but not the timing, is universal. c. The timing, but not the sequence, is universal. d. It is determined solely by environmental factors.

7. Why can’t we consciously recall how we learned to walk when we were infants?

EXPERIENCE THE TESTING EFFECT

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CHAPTER 4 DEVELOPING THROUGH THE LIFE SPAN 161

8. Use Piaget’s first three stages of cognitive development to explain why young children are not just miniature adults in the way they think.

9. Although Piaget’s stage theory continues to inform our understanding of children’s thinking, many researchers believe that

a. Piaget’s “stages” begin earlier and development is more continuous than he realized.

b. children do not progress as rapidly as Piaget predicted. c. few children really progress to the concrete operational

stage. d. there is no way of testing much of Piaget’s theoretical work.

10. An 8-month-old infant who reacts to a new babysitter by crying and clinging to his father’s shoulder is showing .

11. In a series of experiments, the Harlows found that monkeys raised with artificial mothers tended, when afraid, to cling to their cloth mother, rather than to a wire mother holding the feeding bottle. Why was this finding important?

12. From the very first weeks of life, infants differ in their characteristic emotional reactions, with some infants being intense and anxious, while others are easygoing and relaxed. These differences are usually explained as differences in .

13. Adolescence is marked by the onset of a. an identity crisis. b. puberty. c. separation anxiety. d. parent-child conflict.

14. According to Piaget, a person who can think logically about abstractions is in the stage.

15. In Erikson’s stages, the primary task during adolescence is a. attaining formal operations. b. forging an identity. c. developing a sense of intimacy with another person. d. living independent of parents.

16. Some developmental psychologists now refer to the period that occurs in some Western cultures from age 18 to the

mid-twenties and beyond (up to the time of social indepen- dence) as .

17. Developmental researchers who emphasize learning and experience are supporting ; those who emphasize biological maturation are supporting .

a. nature; nurture b. continuity; stages c. stability; change d. randomness; predictability

18. By age 65, a person would be most likely to experience a cognitive decline in the ability to

a. recall and list all the important terms and concepts in a chapter.

b. select the correct definition in a multiple-choice question.

c. recall their own birth date. d. practice a well-learned skill, such as knitting.

19. How do cross-sectional and longitudinal studies differ?

20. Freud defined the healthy adult as one who is able to love and work. Erikson agreed, observing that the adult struggles to attain intimacy and .

21. Contrary to what many people assume, a. older people are much happier than adolescents. b. men in their forties express much greater dissatisfaction

with life than do women of the same age. c. people of all ages report similar levels of happiness. d. those whose children have recently left home—the empty

nesters—have the lowest level of happiness of all groups.

22. Although development is lifelong, there is stability of per- sonality over time. For example,

a. most personality traits emerge in infancy and persist throughout life.

b. temperament tends to remain stable throughout life. c. few people change significantly after adolescence. d. people tend to undergo greater personality changes as

they age.

Find answers to these questions in Appendix E, in the back of the book.

Multiple-format self-tests and more may be found at www.worthpublishers.com/myers.

Experience more of the

TESTING EFFECT

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GENDER DEVELOPMENT How Are We Alike? How Do We Differ?

The Nature of Gender: Our Biology

The Nurture of Gender: Our Culture

HUMAN SEXUALITY The Physiology of Sex

The Psychology of Sex

CLOSE-UP: The Sexualization of Girls

SEXUAL ORIENTATION Environment and Sexual Orientation

Biology and Sexual Orientation

AN EVOLUTIONARY EXPLANATION OF HUMAN SEXUALITY Gender Differences in Sexuality

Natural Selection and Mating Preferences

Critiquing the Evolutionary Perspective

REFLECTIONS ON GENDER, SEXUALITY, AND NATURE–NURTURE INTERACTION

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163

In 1972, as the young chair of our psychology department, I was proud to make the announcement: We had concluded our search for a new colleague. We had found just who we were looking for—a bright, warm, enthusiastic woman about to receive her Ph.D. in developmental psychology. The vote was unanimous. Alas, our elderly chancellor rejected our recommendation. “As a mother of a preschooler,” he said, “she should be home with her child, not working full time.” No amount of pleading or arguing (for example, that it might be possible to parent a child while employed) could change his mind. So, with a heavy heart, I drove to her city to explain, face to face, my embarrassment in being able to offer her only a temporary position.

In this case, all’s well that ends well. She accepted a temporary position and quickly became a beloved, tenured colleague who went on to found our college’s women’s studies program. But today, she and I marvel at the swift transformation in our culture’s thinking about gender. In a thin slice of history, our ideas about the “proper” behavior for women and men have undergone an extreme makeover. Both women and men are now recognized as “fully capable of effectively carrying out organi- zational roles at all levels” (Wood & Eagly, 2002). Women’s employment in formerly male occupations and men’s employment in formerly female occupations have increased. And as this was happening, our views of what is “mas- culine” and what is “feminine” have also changed, as have our ideas about what we seek in a mate (Twenge, 1997).

In this chapter, we’ll look at some of the ways nature and nurture interact to form us as males and females. We’ll see what researchers tell us about how much males and females are alike, and how and why they differ. Along the way, we’ll take a close look at human sexuality. As part of that close look, we’ll see how evolutionary psychologists explain our sexuality.

Let’s start by considering what gender is and how it develops.

Gender and Sexuality

CHAPTERR5

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164 CHAPTER 5 GENDER AND SEXUALITY

Gender Development As we will see in Chapter 9, we humans share an irresistible urge to organize our worlds into simple categories. Among the ways we classify people—as tall or short, fat or slim, smart or dull—one stands out: Before or at your birth, everyone wanted to know, “Boy or girl?” From that time on, your sex (your biological status, defined by your chromo- somes and anatomy) helped define your gender, the socially constructed roles and characteristics by which your culture defines male and female.

How Are We Alike? How Do We Differ?

5-1: What are some gender similarities and differences in aggression, social power, and social connectedness?

Having faced similar adaptive challenges, we are in most ways alike. Tell me whether you are male or female and you give me virtually no clues to your vocabulary, intelligence, and happiness, or to the mechanisms by which you see, hear, learn, and remember. Your “opposite” sex is, in reality, your very similar sex. At conception, you received 23 chromosomes from your mother and 23 from your father. Of those 46 chro- mosomes, 45 are unisex—the same for males and females. (Later in this chapter we’ll return to that forty-sixth chromosome.)

But males and females do differ, and differences command attention—stimulating more than 18,000 studies (Ellis et al., 2008). Some much-talked-about gender differences are actu- ally quite modest, as Janet Shibley Hyde (2005) illustrated by graphically representing male and female self-esteem scores across many studies (FIGURE 5.1). Other differences are more striking. Compared with the average man, the average woman enters puberty 2 years sooner, and her life span is 5 years longer. She carries 70 percent more fat, has 40 percent less muscle, and is 5 inches shorter. She expresses emotions more freely, can smell fainter odors, and is offered help more often. She can become sexually re-aroused soon after orgasm. She is also doubly vulnerable to depression and anxiety, and her risk of developing an eating disorder is 10 times greater than the average man’s. Yet, he is some 4 times more likely to commit suicide or develop alcohol dependence. He is also more likely

to be diagnosed with autism, color - blindness, attention-deficit hyperactivity disorder as a child, and antisocial personality disorder as an adult. Choose your gender and pick your vulnerability.

Gender differences appear throughout this book. For now, let’s consider some gender differences in aggression, social power, and social connectedness.

Gender and Aggression In surveys, men admit to more aggression than women do. This aggression gender gap pertains to harmful physical aggression, rather than indirect or verbal relational aggression such as ostracism or spreading rumors. As John Archer (2004, 2006, 2009) has noted, based on statistical digests of dozen of studies, women may be slightly more likely to commit acts of relational aggression, such as passing along malicious gossip. The gap appears in everyday life at various ages and in various cultures, especially cul- tures with gender inequality (Archer, 2009).

Men’s tendency to behave more aggressively can be seen in experiments where they deliver what they believe are more painful electric shocks (Card et al., 2008).

Pink and blue baby outfits offer another example of how cultural norms vary and change. “The generally accepted rule is pink for the boy and blue for the girl,” declared the publication Earnshaw’s Infants’ Department in June 1918 (Maglaty, 2011). “The reason is that pink being a more decided and stronger color is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girls.”

Females

Males Number

of people

Self-esteem scores Lower scores Higher scores

Self-esteem

FIGURE 5.1

Much ado about a small

difference in self-esteem These two normal distributions differ by the approximate magnitude of the gender difference in self-esteem, averaged over all available samples (Hyde, 2005). Moreover, such comparisons illustrate differences between the average woman and man. The variation among individual women greatly exceeds this difference, as it also does among individual men.

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CHAPTER 5 GENDER AND SEXUALITY 165

Violent crime rates illustrate the gender difference even more strikingly. The male - to - female arrest ratio for murder, for exam- ple, is 9 to 1 in the United States and 8 to 1 in Canada (FBI, 2009; Statistics Canada, 2010). Throughout the world, fighting, warring, and hunting are primarily men’s activities (Wood & Eagly, 2002, 2007). Men also express more support for war. The Iraq war, for example, was consistently supported more by American men than by American women (Newport et al., 2007).

Gender and Social Power Close your eyes and imagine two adults standing side by side. The one on the left is dominant, forceful, and independent. The one on the right is submissive, nurturing, and socially connected.

Did you see the person on the left as a man, and the one on the right as a woman? If so, you are not alone.

Around the world, from Nigeria to New Zealand, people perceive such power dif- ferences between men and women (Williams & Best, 1990). Indeed, in most societies men do place more importance on power and achievement and are socially dominant (Schwartz & Rubel-Lifschitz, 2009). When groups form, whether as juries or compa- nies, leadership tends to go to males (Colarelli et al., 2006). When salaries are paid, those in traditionally male occupations receive more. And when political leaders are elected, they usually are men, who held 80 percent of the seats in the world’s governing parlia- ments in 2011 (IPU, 2011). If perceived to be hungry for political power (thus violating gender norms), women more than men suffer voter backlash (Okimoto & Brescoll, 2010). Men’s power hunger is more expected and accepted.

As leaders, men tend to be more directive, even autocratic. Women tend to be more democratic, more welcoming of subordinates’ input in decision making (Eagly & Carli, 2007; van Engen & Willemsen, 2004). When people interact, men are more likely to utter opinions, women to express support (Aries, 1987; Wood, 1987). In everyday behavior, men tend to act as powerful people often do: They are more likely to talk assertively, interrupt, initiate touches, and stare. And they smile and apologize less (Leaper & Ayres, 2007; Major et al., 1990; Schumann & Ross, 2010). Such behaviors help sustain social power inequities.

Gender and Social Connectedness Females are more interdependent than males, and this difference surfaces early. In chil- dren’s play, boys typically form large groups. Their games tend to be active and competi- tive, with little intimate discussion (Rose & Rudolph, 2006). Studies have found that girls usually play in smaller groups, often with one friend. Their play is less competitive and more imitative of social relationships (Maccoby, 1990; Roberts, 1991).

As adults, women take more pleasure in talking face to face, and they more often use conversation to explore relationships. Men enjoy doing activities side by side and tend to use conversation to communicate solutions (Tannen, 1990; Wright, 1989). The communi- cation difference is apparent in student e-mails: In one New Zealand study, people could correctly guess the author’s gender two-thirds of the time (Thomson & Murachver, 2001).

Gender differences also appear in phone-based communication. In the United States, the average teen girl sends and receives 80 texts daily; the average boy 30 (Lenhart, 2010). In France, women have made 63 percent of phone calls and, when talking to a woman, stayed connected longer (7.2 minutes) than have men when talking to other men (4.6 minutes) (Smoreda & Licoppe, 2000).

Deadly relational aggression This documentary film (www.RatsAndBullies.com) tells the sad tale of 14-year-old Dawn-Marie Wesley, who committed suicide after suffering months of relational aggression by school bullies.

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gender the socially constructed roles and characteristics by which a culture defines male and female.

aggression physical or verbal behavior intended to hurt someone.

Women’s 2011 representation in national parliaments ranged from 11 percent in the Arab States to 42 percent in Scandinavia (IPU, 2011).

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166 CHAPTER 5 GENDER AND SEXUALITY

Every man for himself, or tend and befriend? Gender differences in the way we interact with others begin to appear at a very young age.

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Women worldwide have oriented their interests and vocations more to people and less to things (Eagly, 2009; Lippa, 2005, 2006, 2008). One analysis of more than a half- million people’s responses to various interest inventories revealed that “men prefer working with things and women prefer working with people” (Su et al., 2009). On entering college, American men are seven times more likely than women to express interest in computer science, and they contribute 87 percent of Wikipedia articles (Cohen, 2011; Pryor et al., 2011). In the workplace, women have been less driven by money and status and more often opted for reduced work hours (Pinker, 2008). In the home, they have been five times more likely than men to claim primary responsibility for taking care of children (Time, 2009).

Women’s emphasis on caring helps explain another interesting finding: Although 69 percent of people have said they have a close relationship with their father, 90 percent said they feel close to their mother (Hugick, 1989). When wanting understanding and someone with whom to share worries and hurts, both men and women usually turn to women, and both have reported their friendships with women to be more intimate, enjoyable, and nurturing (Rubin, 1985; Sapadin, 1988). And when coping with their own stress, women more than men turn to others for support—they tend and befriend (Tamres et al., 2002; Taylor, 2002).

Gender differences in social connectedness, power, and other traits peak in late ado- lescence and early adulthood—the very years most commonly studied (also the years of dating and mating). As teenagers, girls become progressively less assertive and more flirtatious; boys become more domineering and unexpressive. Following the birth of a first child, parents (women especially) become more traditional in their gender-related attitudes and behavior (Ferriman et al., 2009; Katz-Wise et al., 2010). But studies have shown that by age 50, parenthood-related gender differences subside. Men become more empathic and less domineering, and women—especially those working outside the home—become more assertive and self-confident (Kasen et al., 2006; Maccoby, 1998).

What explains our diversity? How much does biology bend the genders? To what extent are we shaped by our cultures? A bio psycho social view suggests both are impor- tant, thanks to the interplay among our biological dispositions, our developmental experiences, and our current situations (Eagly, 2009).

RETRIEVE IT

• (Men/Women) are more likely to commit relational aggression, and

(men/women) are more likely to commit physical aggression.

ANSWERS: Women; men

• Worldwide,

(men/women) have tended to express more personal and professional interest in people and less interest in things.

ANSWER: women

“In the long years liker must they grow; The man be more of woman, she of man.”

Alfred Lord Tennyson, The Princess, 1847

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CHAPTER 5 GENDER AND SEXUALITY 167

The Nature of Gender: Our Biology

5-2: How is our biological sex determined, and how do sex hormones influence prenatal and adolescent development?

In domains where we face similar challenges—regulating heat with sweat, preferring foods that nourish, growing calluses where the skin meets friction—men and women are similar. Even when describing the ideal mate, both prize traits such as “kind,” “honest,” and “intelligent.” But in mating-related domains, evolutionary psychologists contend, guys act like guys whether they are elephants or elephant seals, rural peasants or corporate presidents (Geary, 2010). Our biology may influence our gender differences in two ways: genetically, by our differing sex chromosomes, and physiologically, from our differing concentrations of sex hormones.

Prenatal Sexual Development As noted earlier, males and females are variations on a single form—of the 46 chromosomes, 45 are unisex. So great is this similarity that until seven weeks after conception, you were anatomically indistinguishable from someone of the other sex. Then your genes activated your biological sex. Male or female, your sex was determined by your father’s contribution to your twenty-third pair of chromo- somes, the two sex chromosomes. You received an X chromosome from your mother. From your father, you received the one chromosome that is not unisex— either another X chromosome, making you a girl, or a Y chromosome, making you a boy.

The Y chromosome includes a single gene which, about seven weeks after conception, throws a master switch triggering the testes to develop and to pro- duce the principal male hormone, testosterone. This hormone starts the devel- opment of external male sex organs. Females also have testosterone, but less of it.

Another key period for sexual differentiation falls during the fourth and fifth prenatal months. During this period, sex hormones bathe the fetal brain and influence its wiring. Different patterns for males and females develop under the influence of the male’s greater testosterone and the female’s ovarian hormones (Hines, 2004; Udry, 2000).

Adolescent Sexual Development Pronounced physical differences emerge during adolescence, when boys and girls enter puberty and mature sexually. A surge of hormones triggers a two-year period of rapid physical development, usually beginning at about age 11 in girls and at about age 13 in boys. A year or two before that, however, boys and girls often feel the first stirrings of sexual attraction (McClintock & Herdt, 1996).

About the time of puberty, boys’ growth propels them to greater height than their female counterparts (FIGURE 5.2 on the next page). During this growth spurt, the pri- mary sex characteristics—the reproductive organs and external genitalia—develop dramatically. So do secondary sex characteristics, the nonreproductive traits such as breasts and hips in girls, facial hair and deepened voice in boys, and pubic and underarm hair in both sexes (FIGURE 5.3 on the next page).

In various countries, girls are developing breasts earlier (sometimes before age 10) and reaching puberty earlier than in the past. This phenomenon is variously attributed to increased body fat, increased hormone-mimicking chemicals, and increased stress related to family disruption (Biro et al., 2010).

Puberty’s landmarks are the first ejaculation in boys (spermarche), usually by about age 14, and the first menstrual period in girls (menarche—meh- NAR-key), usually within a year of age 12½ (Anderson et al., 2003). Menarche appears to occur a few months ear- lier, on average, for girls who have experienced stresses related to father absence, sexual abuse, or insecure attachments (Belsky et al., 2010; Vigil et al., 2005; Zabin et al., 2005).

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X chromosome the sex chromosome found in both men and women. Females have two X chromosomes; males have one. An X chromo- some from each parent produces a female child.

Y chromosome the sex chromosome found only in males. When paired with an X chromo- some from the mother, it produces a male child.

testosterone the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty.

puberty the period of sexual maturation, during which a person becomes capable of reproducing.

primary sex characteristics the body structures (ovaries, testes, and external genita- lia) that make sexual reproduction possible.

secondary sex characteristics nonre- productive sexual traits, such as female breasts and hips, male voice quality, and body hair.

menarche [meh - NAR-key] the first menstrual period.

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168 CHAPTER 5 GENDER AND SEXUALITY

Girls who have been prepared for menarche usually experience it as a positive life transi- tion. Studies have shown that nearly all adult women recall their first menstrual period and remember experiencing a mixture of feelings—pride, excitement, embarrassment, and apprehension (Greif & Ulman, 1982; Woods et al., 1983). Most men have similarly recalled their first ejaculation, which usually occurs as a nocturnal emission (Fuller & Downs, 1990).

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Height differences Throughout childhood, boys and girls are similar in height. At puberty, girls surge ahead briefly, but then boys overtake them at about age 14. (Data from Tanner, 1978.) Recent studies suggest that sexual development and growth spurts are beginning somewhat earlier than was the case a half - century ago (Herman - Giddens et al., 2001).

FIGURE 5.3

Body changes at puberty At about age 11 in girls and age 13 in boys, a surge of hormones triggers a variety of physical changes.

RETRIEVE IT

• Adolescence is marked by the onset of

.

ANSWER: puberty

Variations on Sexual Development Sometimes nature blurs the biological line between males and females. Atypical hor- mone exposure or sensitivity may cause atypical fetal development. Intersex individuals are born with intermediate or unusual combinations of male and female physical fea- tures. Genetic males, for example, may be born with normal male hormones and testes but without a penis or with a very small one.

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CHAPTER 5 GENDER AND SEXUALITY 169

Until recently, pediatricians and other medical experts often recommended surgery to create a female identity for these children. One study reviewed 14 cases of boys who had undergone early sex - reassignment surgery and had been raised as girls. Of those cases, 6 had later declared themselves as males, 5 were living as females, and 3 had an unclear gender identity (Reiner & Gearhart, 2004).

Although not born with an intersex condition, a little boy who lost his penis during a botched circumcision became a famous case illustrating the prob- lems involved in sex-reassignment surgery. His parents followed a psychiatrist’s advice to raise him as a girl rather than as a damaged boy. Alas, “Brenda” Reimer was not like most other girls. “She” didn’t like dolls. She tore her dresses with rough- and - tumble play. At puberty she wanted no part of kissing boys. Finally, Brenda’s parents explained what had happened, whereupon this young person immediately rejected the assigned female identity. He cut his hair and chose a male name, David. He eventually married a woman and became a stepfather. And, sadly, he later committed suicide (Colapinto, 2000).

The bottom line: “Sex matters,” concluded the National Academy of Sciences (2001). In combination with the environment, sex - related genes and physiology “result in behavioral and cognitive differences between males and females.” Nature and nurture work together.

The Nurture of Gender: Our Culture

5-3: How do gender roles and gender typing influence gender development?

For most people, their biological sex and their gender are tightly interwined. What biology initiates, culture accentuates.

Gender Roles You may recall from Chapter 1 that culture is everything shared by a group and transmit- ted across generations. We can see culture’s shaping power in gender roles—the social expectations that guide men’s and women’s behavior. (In psychology, as in the theater, a role refers to a cluster of prescribed actions, the behaviors we expect of those who occupy a particular social position.)

Gender roles vary over time and place. In North America, men were traditionally expected to initiate dates, drive the car, and pick up the check. Women were expected to decorate the home, buy and care for the children’s clothes, and select the wedding gifts. Up through the 1990s, Mom (about 90 percent of the time in two - parent U.S. families) stayed home with a sick child, arranged for the baby sitter, and called the doctor (Mac- coby, 1995). Even in recent years, compared with employed women, employed men in the United States have spent about an hour and a half more on the job and about one hour less on daily household activities and caregiving (Amato et al., 2007; Bureau of Labor Statistics, 2004; Fisher et al., 2006). Ditto Australia, where, compared with men, women have devoted 54 percent more time to unpaid household work and 71 percent more time to child care (Trewin, 2001).

Other societies have different expectations. In nomadic societies of food - gathering people, there is little division of labor by sex. Boys and girls receive much the same upbringing. In agricultural societies, where women work in the nearby fields and men roam while herding livestock, children have typically been socialized into more distinct gender roles (Segall et al., 1990; Van Leeuwen, 1978).

Among industrialized countries, gender roles and attitudes vary widely. Australia and the Scandinavian countries offer the greatest gender equity, Middle Eastern and North African countries the least (Social Watch, 2006). And consider: Would you agree that “when jobs are scarce, men should have more rights to a job?” In the United States, Britain, and Spain, about one in eight adults agree. In Nigeria, Pakistan, and India, about four in five do (Pew, 2010). We are one species, but my how we differ.

Reuters/Michael Dalder

Gender in the spotlight Dramatic improvements in South African track star Caster Semenya’s race times prompted the Interna-

tional Association of Athletics Federations to undertake sex testing in 2009.

Semenya was reported to be intersex—with physical characteris- tics of both males and

females—though she was officially cleared to continue competing as a woman. Semenya declared, “God made me the way I am and I accept myself. I am who I am” (YOU, 10 September 2009).

“Sex brought us together, but gender drove us apart.”

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gender role a set of expected behaviors for males or for females.

role a set of expectations (norms) about a social position, defining how those in the posi- tion ought to behave.

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170 CHAPTER 5 GENDER AND SEXUALITY

To see how gender role attitudes vary over time, consider women’s vot- ing rights. At the opening of the twentieth century, only one country— New Zealand—granted women the right to vote (Briscoe, 1997). By the late 1960s and early 1970s, women had become a force in the vot- ing booth and the workplace in many countries. Nearly 50 percent of employed Americans are now women, as are 54 percent of college graduates, up from 36 percent in just four decades (Fry & Cohn, 2010). In today’s postindustrial economy, the jobs expected to grow the most in the years ahead are the ones women have gravitated toward—those that require not size and strength but social intelligence, open commu- nication, and the ability to sit still and focus (Rosin, 2010). These are big gender changes in but a thin slice of history.

Gender roles can smooth social relations, avoiding irritating discus- sions about whose job it is to get the car fixed and who should buy the birthday presents. But these quick and easy assumptions come at a cost: If we deviate from conventions, we may feel anxious.

How Do We Learn to Be Male or Female? Gender identity is a person’s sense of being male or female. Social learning theory assumes that children acquire this identity by observing and imitating oth- ers’ gender-linked behaviors and by being rewarded or punished for acting in certain ways themselves (“Nicole, you’re such a good mommy to your dolls”; “Big boys don’t cry, Alex.”). Some critics have objected, saying that parental modeling and rewarding of male-female differences aren’t enough to explain gender typing, the way some children seem more attuned than others to traditional male or female roles (Lytton & Romney, 1991). In fact, even in families that discourage traditional gender typing, children organize themselves into “boy worlds” and “girl worlds,” each guided by rules for what boys and girls do.

Cognition (thinking) also matters. In your own childhood you formed schemas, or concepts that helped you make sense of your world. One of these was your gender schema, your framework for organizing boy-girl characteristics (Bem, 1987, 1993). This gender schema then became a lens through which you viewed your experiences.

Gender schemas form early in life, and social learning helps form them. Before age 1, you began to discriminate male and female voices and faces (Martin et al., 2002). After age 2, language forced you to begin organizing your world on the basis of gender. English, for example, uses the pronouns he and she; other languages classify objects as masculine (“le train”) or feminine (“la table”).

Young children are “gender detectives” (Martin & Ruble, 2004). Once they grasp that two sorts of people exist—and that they are of one sort—they search for clues

about gender, and they find them in language, dress, toys, and songs. Girls, they may decide, are the ones with long hair. Hav- ing divided the human world in half, 3-year - olds will then like their own kind better and seek them out for play. And having compared themselves with their concept of gender, they will adjust their behavior accordingly. (“I am male—thus, mascu- line, strong, aggressive,” or “I am female—therefore, feminine, sweet, and helpful.”) These rigid boy-girl stereotypes peak at about age 5 or 6. If the new neighbor is a boy, a 6-year- old girl may assume he just cannot share her interests. For young chil- dren, gender looms large.

For some people, comparing themselves with their culture’s concepts of gender produces feelings of confusion and dis- cord. Transgender people’s gender identity (their sense of being male or female) or gender expression (their communication of gender identity through behavior or appearance) differs from

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The gendered tsunami In Sri Lanka, Indonesia, and India, the gendered division of labor helps explain the excess of female deaths from the 2004 tsunami. In some villages, 80 percent of those killed were women, who were mostly at home while the men were more likely to be at sea fishing or doing out - of - the - home chores (Oxfam, 2005).

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CHAPTER 5 GENDER AND SEXUALITY 171

The transgender mayor When Stu Rassmussen was elected Silverton, Oregon’s mayor, he was a guy in pants. When reelected, he was openly transgender and wore a dress and makeup to his installation.

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gender identity our sense of being male or female.

social learning theory the theory that we learn social behavior by observing and imitating and by being rewarded or punished.

gender typing the acquisition of a tradi- tional masculine or feminine role.

transgender an umbrella term describing people whose gender identity or expression dif- fers from that associated with their birth sex.

estrogens sex hormones, such as estra- diol, secreted in greater amounts by females than by males and contributing to female sex characteristics. In nonhuman female mammals, estrogen levels peak during ovulation, promot- ing sexual receptivity.

“The more I was treated as a woman, the more woman I became.”

Jan Morris, male-to-female transsexual

that typical of their birth sex (APA, 2010). A person may feel like a man in a woman’s body, or a woman in a man’s body. These include transsexual people, who live, or wish to live, as members of the gender opposite to their birth sex, often aided by medical treatment that supports gender reassignment. Note that gender identity is distinct from sexual orientation (the direction of one’s sexual attraction). Transgender people may be heterosexual, homosexual, bisexual, or asexual.

Some transgender persons express their gender identity by dressing as a person of the other biological sex typically would. Most cross-dressers are biological males, the major- ity of whom feel an attraction to females (APA, 2010).

RETRIEVE IT

• What are gender roles, and what do their variations tell us about our human capacity for learning and adaptation?

ANSWER: Gender roles are sets of expected behaviors for females or for males. Gender roles vary widely in different cultures, which is proof that we are very capable of learning and adapting to the social demands of different environments.

Human Sexuality As you’ve probably noticed, we can hardly talk about gender without talking about our sexuality. For all but the tiny fraction of us considered asexual, dating and mating become top priority from puberty on. Physiological and psychological influences affect our sexual feelings and behaviors.

The Physiology of Sex Sex is not like hunger, because it is not an actual need. (Without it, we may feel like dying, but we will not.) Yet sex is part of life. Had this not been so for all your ancestors, you would not be reading this book. Sexual motivation is nature’s clever way of making people procreate, thus enabling our species’ survival. When two people feel an attraction, they hardly stop to think of themselves as guided by their genes. As the pleasure we take in eating is nature’s method of getting our body nourishment, so the desires and pleasures of sex are our genes’ way of preserving and spreading themselves. Life is sexually transmitted.

Hormones and Sexual Behavior

5-4: How do hormones influence human sexual motivation?

Among the forces driving sexual behavior are the sex hormones. The main male sex hormone, as we saw earlier, is testosterone. The main female sex hormones are

the estrogens, such as estradiol. Sex hormones influence us at many points in the life span:

• During the prenatal period, they direct our development as males or females. • During puberty, a sex hormone surge ushers us into adolescence. • After puberty and well into the late adult years, sex hormones activate sexual behavior.

In most mammals, nature neatly synchronizes sex with fertility. Females become sexually receptive (“in heat”) when their estrogens peak at ovulation. In experiments, researchers can cause female animals to become receptive by injecting them with estrogens. Male hormone levels are more constant, and hormone injection does not so easily manipulate the sexual behavior of male animals (Feder, 1984). Nevertheless, male rats that have had their testes (which manufacture testosterone) surgically removed will gradually lose much of their interest in receptive females. They gradually regain it if injected with testosterone.

In a British survey of 18,876 people, 1 percent were seemingly asexual, having “never felt sexually attracted to anyone at all” (Bogaert, 2004, 2006b).

“It is a near-universal experience, the invisible clause on one’s birth certificate stipulating that one will, upon reaching maturity, feel the urge to engage in activities often associated with the issuance of more birth certificates.”

Science writer Natalie Angier, 2007

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172 CHAPTER 5 GENDER AND SEXUALITY

Hormones do influence human sexual behavior, but in a looser way. Among women with mates, sexual desire rises slightly at ovulation (Pillsworth et al., 2004). One study invited partnered women not at risk for pregnancy to keep a diary of their sexual activ- ity. (These women were either using intrauterine devices or had undergone surgery to prevent pregnancy.) On the days around ovulation, intercourse was 24 percent more frequent (Wilcox et al., 2004).

Other studies find that around ovulation, women fantasize more about sex with desirable partners, wear more sexually attractive clothing, and have slightly higher voice pitch (Bryant & Haselton, 2009; Pillsworth & Haselton, 2006; Sheldon et al., 2006). After sniffing a T-shirt worn by a woman, men display higher testosterone levels if she was ovulating rather than nonovulating (Miller & Maner, 2010, 2011). In a study of 5300 strip-club lap dancers, their hourly tips almost doubled on the days near ovulation, compared with days during menstruation (Miller et al., 2007).

Women more than other mammalian females are responsive to their testosterone level (van Anders & Dunn, 2009). You may recall that women have testosterone, though at lower levels than are found in men. If a woman’s natural testosterone level drops, as hap- pens with removal of the ovaries or adrenal glands, her sexual interest may wane. But as controlled experiments with hundreds of surgically or naturally menopausal women have demonstrated, testosterone - replacement therapy can often restore diminished sexual activ- ity, arousal, and desire (Braunstein et al., 2005; Buster et al., 2005; Petersen & Hyde, 2011).

In human males with abnormally low testosterone levels, testosterone - replacement therapy often increases sexual desire and also energy and vitality (Yates, 2000). But normal fluctuations in testosterone levels, from man to man and hour to hour, have little effect on sexual drive (Byrne, 1982). Indeed, male hormones sometimes vary in response to sexual stimulation. In one study, Australian skateboarders’ testosterone surged in the presence of an attractive female, contributing to riskier moves and more crash landings (Ronay & von Hippel, 2010). Thus, sexual arousal can be a cause as well as a consequence of increased tes- tosterone levels. At the other end of the mating spectrum, studies in both North America and China have found that married fathers tend to have lower testosterone levels than do bachelors and married men without children (Gray et al., 2006).

Large hormonal surges or declines do affect men and women’s desire. These shifts tend to occur at two predictable points in the life span, and sometimes at an unpredict- able third point:

1. As we have seen, a surge in sex hormones triggers the development of sex characteristics during puberty. Interest in dating and sexual stimulation usually increases at this time. If the hormonal surge is precluded—as it was during the 1600s and 1700s for prepubertal boys who were castrated to preserve their soprano voices for Italian opera—sex char- acteristics and sexual desire do not develop normally (Peschel & Peschel, 1987).

2. In later life, estrogen levels fall, and women experience menopause (Chapter 4). As sex hor- mone levels decline, the frequency of sexual fantasies and intercourse declines as well (Leitenberg & Henning, 1995).

3. For some, surgery or drugs may cause hormonal shifts. When adult men were castrated, sex drive typically fell as testosterone levels declined sharply (Hucker & Bain, 1990). Male sex offenders who were tak- ing Depo - Provera, a drug that reduces testosterone levels to that of a prepubertal boy, have similarly lost much of their sexual urge (Bilefsky, 2009; Money et al., 1983).

To summarize: We might compare human sex hormones, especially tes- tosterone, to the fuel in a car. Without fuel, a car will not run. But if the fuel level is minimally adequate, adding more fuel to the gas tank won’t change how the car runs. The analogy is imperfect, because hormones and sexual motivation interact. However, it correctly suggests that biol- ogy is a necessary but not sufficient explanation of human sexual behav- ior. The hormonal fuel is essential, but so are the psychological stimuli that turn on the engine, keep it running, and shift it into high gear.“Fill’er up with testosterone.”

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CHAPTER 5 GENDER AND SEXUALITY 173

RETRIEVE IT

• The primary male sex hormone is

. The primary female sex hormones are the

.

ANSWERS: testosterone; estrogens

The Sexual Response Cycle

5-5: What is the human sexual response cycle, and how do sexual dysfunctions and paraphilias differ?

In the 1960s, gynecologist - obstetrician William Masters and his collaborator Virginia Johnson (1966) made headlines by recording the physiological responses of vol- unteers who came to their lab to masturbate or have intercourse. With the help of 382 female and 312 male volunteers—a somewhat atypical sample, consisting only of people able and willing to display arousal and orgasm while scientists observed—Masters and Johnson monitored or filmed more than 10,000 sexual “cycles.” Their description of the sexual response cycle identified four stages:

1. Excitement: The genital areas become engorged with blood, causing a woman’s clito- ris and a man’s penis to swell. A woman’s vagina expands and secretes lubricant; her breasts and nipples may enlarge.

2. Plateau: Excitement peaks as breathing, pulse, and blood pressure rates continue to increase. A man’s penis becomes fully engorged and some fluid—frequently contain- ing enough live sperm to enable conception—may appear at its tip. A woman’s vagi- nal secretion continues to increase, and her clitoris retracts. Orgasm feels imminent.

3. Orgasm: Muscle contractions appear all over the body and are accompanied by fur- ther increases in breathing, pulse, and blood pressure rates. A woman’s arousal and orgasm facilitate conception: They help propel semen from the penis, position the uterus to receive sperm, and draw the sperm further inward, increasing retention of deposited sperm (Furlow & Thornhill, 1996). The pleasurable feeling of sexual release apparently is much the same for both sexes. One panel of experts could not reliably distinguish between descriptions of orgasm written by men and those written by women (Vance & Wagner, 1976). In another study, PET scans showed that the same subcortical brain regions were active in men and women during orgasm (Holstege et al., 2003a,b). And when people passionately in love undergo fMRI scans while viewing photos of their beloved or of a stranger, men’s and women’s brain responses to their partner are pretty similar (Fisher et al., 2002).

4. Resolution: The body gradually returns to its unaroused state as the genital blood vessels release their accumulated blood. This happens relatively quickly if orgasm has occurred, relatively slowly otherwise. (It’s like the nasal tickle that goes away rapidly if you have sneezed, slowly otherwise.) Men then enter a refractory period that lasts from a few minutes to a day or more, during which they are incapable of another orgasm. A woman’s much shorter refractory period may enable her to have another orgasm if restimulated during or soon after resolution.

Sexual Dysfunctions and Paraphilias Masters and Johnson sought not only to describe the human sexual response cycle but also to understand and treat the inability to complete it. Sexual dysfunctions are problems that consistently impair sexual arousal or functioning. Some involve sexual motivation, especially lack of sexual energy and arousability. For men, others include erectile dysfunction (inability to have or maintain an erection) and premature ejaculation. For women, the problem may be pain or orgasmic dysfunction (distress over infrequently or never experiencing orgasm). In separate surveys of some 3000 Boston women and 32,000 other American women, about 4 in 10 reported a sexual problem, such as

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A nonsmoking 50-year-old male has about a 1-in-a-million chance of a heart attack during any hour. This increases to merely 2-in-a-million in the two hours during and following sex (with no increase for those who exercise regularly). Compared with risks associated with heavy exertion or anger (see Chapter 11), this risk seems not worth losing sleep (or sex) over (Jackson, 2009; Muller et al., 1996).

sexual response cycle the four stages of sexual responding described by Masters and Johnson—excitement, plateau, orgasm, and resolution.

refractory period a resting period after orgasm, during which a man cannot achieve another orgasm.

sexual dysfunction a problem that con- sistently impairs sexual arousal or functioning.

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174 CHAPTER 5 GENDER AND SEXUALITY

orgasmic dysfunction or low desire, but only about 1 in 8 reported that this caused personal distress (Lutfey et al., 2009; Shifren et al., 2008). Most women who have expe- rienced sexual distress have related it to their emotional relationship with the partner during sex (Bancroft et al., 2003).

Therapy can help men and women with sexual dysfunction. In behaviorally oriented therapy, for example, men learn ways to control their urge to ejaculate, and women are trained to bring themselves to orgasm. Starting with the introduction of Viagra in 1998, erectile dysfunction has been routinely treated by taking a pill.

In the more troubling paraphilias, a person’s sexual arousal is related to socially unac- ceptable behavior. The American Psychiatric Association classifies such behavior as disordered if a person’s sexual urges, fantasies, or behaviors involve nonhuman objects; the suffering of self or others; and/or nonconsenting persons. Examples of paraphilias include exhibitionism, fetishism, and pedophilia.

Sexually Transmitted Infections

5-6: How can sexually transmitted infections be prevented?

Rates of sexually transmitted infections (STIs; also called STDs for sexually trans- mitted diseases) are rising, and two - thirds of the new infections have occurred

in people under 25 (CASA, 2004). Teenage girls, because of their not yet fully mature biological development and lower levels of protective antibodies, are especially vulner- able (Dehne & Riedner, 2005; Guttmacher, 1994). A Centers for Disease Control study of sexually experienced 14- to 19-year-old U.S. females found 39.5 percent had STIs (Forhan et al., 2008).

To comprehend the mathematics of infection transmission, imagine this scenario. Over the course of a year, Pat has sex with 9 people, each of whom over the same period has sex with 9 other people, who in turn have sex with 9 others. How many “phantom” sex partners (past partners of partners) will Pat have? The actual number—511—is more than five times the estimate given by the average student (Brannon & Brock, 1993).

Condoms offer only limited protection against certain skin - to - skin STIs, such as herpes, but they do reduce other risks (Medical Institute, 1994; NIH, 2001). The effects were clear when Thailand promoted 100 percent condom use by commercial sex work- ers. Over a four-year period, as condom use soared from 14 to 94 percent, the annual number of bacterial STIs plummeted from 410,406 to 27,362 (WHO, 2000).

Across the available studies, condoms also have been 80 percent effective in prevent- ing transmission of HIV (human immunodeficiency virus—the virus that causes AIDS) from an infected partner (Weller & Davis-Beaty, 2002; WHO, 2003). Although AIDS can be transmitted by other means, such as needle sharing during drug use, its sexual transmission is most common. Women’s AIDS rates are increasing fastest, partly because the virus is passed from man to woman much more often than from woman to man. A man’s semen can carry more of the virus than can a woman’s vaginal and cervical secre- tions. The HIV-infected semen can also linger for days in a woman’s vagina and cervix, increasing the time of exposure (Allen & Setlow, 1991; WHO, 2004).

Most U.S. AIDS cases have been people in midlife and younger—ages 25 to 44 (U.S. Centers for Disease Control and Prevention, 2011). Given AIDS’ long incubation period, this means that many of these young people were infected as teens. In 2009, the death of 1.8 million AIDS victims worldwide left behind countless grief-stricken part- ners and millions of orphaned children (UNAIDS, 2010). Sub-Saharan Africa is home to two-thirds of those infected with HIV, and medical treatment and care for the dying are sapping the region’s social resources.

Many people assume that oral sex falls in the category of “safe sex,” but recent stud- ies show a significant link between oral sex and transmission of STIs, such as the human papilloma virus (HPV). Risks rise with the number of sexual partners (Gillison et al., 2012). Most HPVs can now be prevented with a vaccination administered before sexual contact.

AIDS (acquired immune deficiency syndrome) a life-threatening, sexually transmitted infection caused by the human immunodeficiency virus (HIV). AIDS depletes the immune system, leaving the person vulner- able to infections.

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CHAPTER 5 GENDER AND SEXUALITY 175

RETRIEVE IT

• The inability to complete the sexual response cycle may be considered a

. Exhibitionism would be considered a

.

ANSWERS: sexual dysfunction; paraphilia

• From a biological perspective, AIDS is passed more readily from women to men than from men to women. True or false?

ANSWER: False. AIDS is transmitted more easily and more often from men to women.

The Psychology of Sex

5-7: How do external and imagined stimuli contribute to sexual arousal?

Biological factors powerfully influence our sexual motivation and behavior. Yet the wide variations over time, across place, and among individuals document the great influence of psychological factors as well (FIGURE 5.4). Thus, despite the shared biology that underlies sexual motivation, the 281 expressed reasons for having sex (at last count) ranged widely—from “to get closer to God” to “to get my boyfriend to shut up” (Buss, 2008; Meston & Buss, 2007).

External Stimuli Men and women become aroused when they see, hear, or read erotic material (Heiman, 1975; Stockton & Murnen, 1992). In 132 experiments, men’s feelings of sexual arousal have much more closely mirrored their (more obvious) genital response than have women’s (Chivers et al., 2010).

People may find sexual arousal either pleasing or disturbing. (Those who wish to control their arousal often limit their exposure to such materials, just as those wishing to control hunger limit their exposure to tempting cues.) With repeated exposure, the emotional response to any erotic stimulus often lessens, or habituates. During the 1920s, when Western women’s rising hemlines first reached the knee, an exposed leg was a mildly erotic stimulus.

Can exposure to sexually explicit material have adverse effects? Research has indi- cated that it can. Depictions of women being sexually coerced—and liking it—have increased viewers’ acceptance of the false idea that women enjoy rape, and have increased male viewers’ willingness to hurt women (Malamuth & Check, 1981; Zillmann, 1989). Viewing images of sexually attractive women and men may also lead people to devalue their own partners and relationships. After male collegians viewed TV or magazine

Biological influences: Psychological influences:

Social-cultural influences:

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sexual motivation Our sexual motivation is influenced by biological factors, but psychological and social-cultural factors play an even bigger role.

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“Condoms should be used on every conceivable occasion.”

Anonymous

depictions of sexually attractive women, they often found an average woman, or their own girlfriend or wife, less attractive (Kenrick & Gutierres, 1980; Kenrick et al., 1989; Weaver et al., 1984). Viewing X-rated sex films has similarly tended to diminish people’s satisfaction with their own sexual partner (Zillmann, 1989). Perhaps reading or watching erotica creates expectations that few men and women can fulfill.

Imagined Stimuli The brain, it has been said, is our most significant sex organ. The stimuli inside our heads— our imagination—can influence sexual arousal and desire. People who, because of a spinal- cord injury, have no genital sensation can still feel sexual desire (Willmuth, 1987).

Wide - awake people become sexually aroused not only by memories of prior sexual activities but also by fantasies. About 95 percent of both men and women have said they have sexual fantasies. Men (whether gay or straight) fantasize about sex more often, more physically, and less romantically. They also prefer less personal and faster - paced sexual content in books and videos (Leitenberg & Henning, 1995). Fantasizing about sex does not indicate a sexual problem or dissatisfaction. If anything, sexually active people have more sexual fantasies.

RETRIEVE IT

• What factors influence our sexual motivation and behavior?

ANSWER: Influences include biological factors such as sexual maturity and sex hormones, psychological factors such as environmental stimuli and fantasies, and social-cultural factors such as the values and expectations absorbed from family and the surrounding culture.

Teen Pregnancy

5-8: What factors influence teenagers’ sexual behaviors and use of contraceptives?

Compared with European teens, American teens have a higher rate of STIs and also of teen pregnancy (Call et al., 2002; Sullivan/Anderson, 2009). What environ- mental factors contribute to teen pregnancy?

Minimal communication about birth control Many teenagers are uncomfortable discussing contraception with their parents, partners, and peers. Teens who talk freely with parents, and who are in an exclusive relationship with a partner with whom they communicate openly, are more likely to use contraceptives (Aspy et al., 2007; Milan & Kilmann, 1987).

Guilt related to sexual activity In another survey, 72 percent of sexually active 12- to 17-year - old American girls said they regretted having had sex (Reuters, 2000). Sexual inhibitions or ambivalence can restrain sexual activity, but if passion overwhelms inten- tions they may also reduce attempts at birth control (Gerrard & Luus, 1995; MacDonald & Hynie, 2008).

Alcohol use Sexually active teens are typically alcohol - using teens (Zimmer-Gem- beck & Helfand, 2008), and those who use alcohol prior to sex are less likely to use condoms (Kotchick et al., 2001). By depressing the brain centers that control judgment, inhibition, and self - awareness, alcohol disarms normal restraints, a phenomenon well known to sexually coercive males.

Mass media norms of unprotected promiscuity Media help write the “social scripts” that affect our perceptions and actions. So what sexual scripts do today’s media write on our minds? An average hour of prime - time television on the three major U.S. networks has contained 15 sexual acts, words, and innuendos. The partners were usually unmar- ried, with no prior romantic relationship, and few communicated any concern for birth control or STIs (Brown et al., 2002; Kunkel, 2001; Sapolsky & Tabarlet, 1991). The more

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CHAPTER 5 GENDER AND SEXUALITY 177

sexual content adolescents view (even when controlling for other predictors of early sexual activity), the more likely they are to perceive their peers as sexually active, to develop sexually permissive attitudes, and to experience early inter- course (Escobar-Chaves et al., 2005; Martino et al., 2005; Ward & Friedman, 2006). (See Close-Up: The Sexualization of Girls.)

The National Longitudinal Study of Adolescent Health among 12,000 teens found several factors that predicted several sexual restraint:

• High intelligence Teens with high rather than average intelligence test scores more often delayed sex, partly because they appreciated possi- ble negative consequences and were more focused on future achieve- ment than on here - and - now pleasures (Halpern et al., 2000).

• Religious engagement Actively religious teens have more often reserved sexual activity for adulthood (Lucero et al., 2008).

• Father presence In studies that followed hundreds of New Zealand and U.S. girls from age 5 to 18, a father’s absence was linked to sexual activ- ity before age 16 and to teen pregnancy (Ellis et al., 2003). These asso- ciations held even after adjusting for other adverse influences, such as poverty. Close family attachments—families that eat together and where parents know their teens’ activities and friends—also predicted later sexual initiation (Coley et al., 2008).

• Participation in service learning programs Several experiments have found that teens volunteering as tutors or teachers’ aides, or participating in community projects, had lower pregnancy rates than were found among comparable teens randomly assigned to control conditions (Kirby, 2002; O’Donnell et al., 2002). Researchers are unsure why. Does service learning promote a sense of personal competence, control, and responsibility? Does it encourage more future - oriented thinking? Or does it simply reduce opportunities for unprotected sex?

* * * We have considered some of the research on the biological and psychological aspects of human sexuality. It’s important to remember, though, that scientific research on human sexuality does not aim to define the personal meaning of sex in our own lives. We could know every available fact about sex—that the initial spasms of male and female orgasm

Eidos Scripps Howard Photo Service/Newscom

Keeping abreast of hypersexuality An analysis of the 60 top-selling video games found 489 characters, 86 percent of whom were males (like most of the game players). The female characters were much more likely than the male characters to be “hyper- sexualized”—partially nude or revealingly clothed, with large breasts and tiny waists (Downs & Smith, 2010).

The Sexualization of Girls

CLOSE UP:

As you have surely noticed, TV, the Internet, music videos and lyrics, movies, magazines, sports media, and advertising often portray women and even girls as sexual objects. The frequent result, according to both an American Psychological Association (APA, 2007) task force and the Scottish Parliament (2010), is harm to their self-image, and unhealthy sexual development.

Sexualization occurs when girls

• are led to value themselves in terms of their sexual appeal.

• compare themselves to narrowly defined beauty standards.

• see themselves as sexual beings for others’ use.

In experiments, the APA task force reported, being made self-conscious about one’s body, such as by wearing a swimsuit, disrupts thinking when doing math computations or logical reason- ing. Sexualization also contributes to eating disorders and depres- sion, and to unrealistic expecta- tions regarding sexuality.

Mindful of today’s sexual- izing media, the APA has some suggestions for countering these

messages. Parents, teachers, and others can teach girls “to value them- selves for who they are rather than how they look.” They can teach boys “to value girls as friends, sisters, and girlfriends, rather than as sexual objects.” And they can help girls and boys develop “media literacy

skills” that enable them to rec- ognize and resist the message that women are sexual objects and that a thin, sexy look is all

that matters.

© T. Arroyo/JPegFoto/PictureGroup via AP Images

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178 CHAPTER 5 GENDER AND SEXUALITY

sexual orientation an enduring sexual attraction toward members of either one’s own sex (homosexual orientation), the other sex (heterosexual orientation), or both sexes (bisexual orientation).

Sharing love For most adults, a sexual relationship fulfills not only a biological motive but also a social need for intimacy.

Image Source/Getty Images

come at 0.8-second intervals, that the female nipples expand 10 millimeters at the peak of sexual arousal, that systolic blood pressure rises some 60 points and respiration rate to 40 breaths per minute—but fail to understand the human significance of sexual intimacy.

Surely one significance of sexual intimacy is its expression of our profoundly social nature. One recent study asked 2035 married people when they started having sex (while controlling for education, religious engagement, and relationship length). Those whose relationship first developed to a deep commitment reported greater relationship satisfaction and stability—and better sex (Busby et al., 2010). Sex is a socially significant act. Men and women can achieve orgasm alone, yet most people find greater satisfac- tion—and experience a much greater surge in the prolactin hormone associated with sexual satisfaction and satiety—after intercourse and orgasm with their loved one (Brody & Tillmann, 2006). Sex at its human best is life uniting and love renewing.

In the remaining pages of this chapter, we’ll consider two special topics: sexual orienta- tion (the direction of our sexual interests), and evolutionary psychology’s explanation of our sexual motivation.

RETRIEVE IT

• Which THREE of the following five factors contribute to unplanned teen pregnancies?

a. Alcohol use d. Mass media models

b. Higher intelligence level e. Increased communication about options

c. Ignorance

ANSWERS: a, c, d

Sexual Orientation 5-9: What has research taught us about sexual orientation?

We express the direction of our sexual interest in our sexual orientation—our enduring sexual attraction toward members of our own sex (homosexual orienta-

tion), the other sex (heterosexual orientation), or both sexes (bisexual orientation). As far as we know, all cultures in all times have been predominantly heterosexual (Bullough, 1990). Some cultures have condemned same-sex relations. (In Kenya and Nigeria, 98 percent have thought homosexuality is “never justified” [Pew, 2006].) Others have accepted same- sex unions. But in both cases, heterosexuality prevails and homosexuality endures.

How many people are exclusively homosexual? About 10 percent, as the popular press has often assumed? Nearly 25 percent, as average Americans estimated in a 2011 Gallup survey (Morales, 2011)? Not according to more than a dozen national surveys that have explored sexual orientation in Europe and the United States, using methods protecting the respondents’ anonymity. The most accurate figure seems to be about 3 percent of men and 1 or 2 percent of women (Chandra et al., 2011; Herbenick et al., 2010a). Fewer than 1 percent of survey respondents—for example, only 12 people out of 7076 Dutch adults in one survey (Sandfort et al., 2001)—have reported being actively bisexual. A larger num- ber of adults—13 percent of women and 5 percent of men in a U.S. National Center for Health Statistics survey—report some same-sex sexual contact during their lives (Chandra et al., 2011). And still more have had an occasional homosexual fantasy.

What does it feel like to be the “odd man (or woman) out” in a heterosexual culture? If you are heterosexual, one way to understand is to imagine how you would feel if you were socially isolated for openly admitting or displaying your feelings toward someone of the other sex. How would you react if you overheard people making crude jokes about het- erosexual people, or if most movies, TV shows, and advertisements portrayed (or implied) homosexuality? And how would you answer if your family members were pleading with you to change your heterosexual life style and to enter into a homosexual marriage?

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CHAPTER 5 GENDER AND SEXUALITY 179

Facing such reactions, homosexual people often struggle with their sexual orienta- tion. They may at first try to ignore or deny their desires, hoping they will go away. But they don’t. Some may try to change, through psychotherapy, willpower, or prayer. But the feelings typically persist, as do those of heterosexual people—who are similarly incapable of becoming homosexual (Haldeman, 1994, 2002; Myers & Scanzoni, 2005).

Most of today’s psychologists therefore view sexual orientation as neither willfully chosen nor willfully changed. “Efforts to change sexual orientation are unlikely to be successful and involve some risk of harm,” declared a 2009 American Psychological Association report. In 1973, the American Psychiatric Association dropped homosexu- ality from its list of “mental illnesses.” In 1993, the World Health Organization did the same, as did Japan’s and China’s psychiatric associations in 1995 and 2001. Some have noted that rates of depression and attempted suicide are higher among gays and lesbians. Many psychologists believe, however, that these symptoms may result from experiences with bullying, harassment, and discrimination (Sandfort et al., 2001; Warner et al., 2004). “Homosexuality, in and of itself, is not associated with mental disorders or emotional or social problems,” declared the American Psychological Association (2007).

Thus, sexual orientation in some ways is like handedness: Most people are one way, some the other. A very few are ambidextrous. Regardless, the way one is endures.

This conclusion is most strongly established for men. Compared with men’s sexual orientation, women’s tends to be less strongly felt and may be more variable (Chivers, 2005; Diamond, 2008; Peplau & Garnets, 2000). Men’s lesser erotic plasticity (sexual vari- ability) is apparent in many ways (Baumeister, 2000). Adult women’s sexual drive and interests are more flexible and varying than are adult men’s. Women, more than men, for example, prefer to alternate periods of high sexual activity with periods of almost none. They are also somewhat more likely than men to feel and act on bisexual attractions (Mosher et al., 2005).

Environment and Sexual Orientation So, our sexual orientation is something we do not choose and (especially for males) seemingly cannot change. Where, then, do these preferences come from? Let’s look first at possible environmental influences on sexual orientation. To see if you can anticipate the conclusions that have emerged from hundreds of studies, try answering Yes or No to these questions:

1. Is homosexuality linked with problems in a child’s relationships with parents, such as with a domineering mother and an ineffectual father, or a possessive mother and a hostile father?

2. Does homosexuality involve a fear or hatred of people of the other sex, leading indi- viduals to direct their desires toward members of their own sex?

3. Is sexual orientation linked with levels of sex hormones currently in the blood?

4. As children, were most homosexuals molested, seduced, or otherwise sexually victim- ized by an adult homosexual?

The answer to all these questions has been No (Storms, 1983). In a search for possible environmental influences on sexual orientation, Kinsey Institute inves- tigators interviewed nearly 1000 homo- sexuals and 500 heterosexuals. They assessed nearly every imaginable psycho- logical cause of homosexuality—parental relationships, childhood sexual experi- ences, peer relationships, and dating expe- riences (Bell et al., 1981; Hammersmith, 1982). Their findings: Homosexuals were

Note that the scientific question is not “What causes homosexuality?” (or “What causes heterosexuality?”) but “What causes differing sexual orientations?” In pursuit of answers, psychological science compares the backgrounds and physiology of people whose sexual orientations differ.

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Personal values affect sexual orientation less than they affect other forms of sexual behavior Compared with people who rarely attend religious services, for example, those who attend regularly are one-third as likely to have lived together before marriage, and they report having had many fewer sex part- ners. But (if male) they are just as likely to be homosexual (Smith, 1998).

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no more likely than heterosexuals to have been smothered by maternal love or neglected by their father. And consider this: If “distant fathers” were more likely to produce homo- sexual sons, then shouldn’t boys growing up in father - absent homes more often be gay? (They are not.) And shouldn’t the rising number of such homes have led to a noticeable increase in the gay population? (It has not.) Most children raised by gay or lesbian par- ents grow up straight and well-adjusted (Gartrell & Bos, 2010).

A bottom line has emerged from a half - century’s theory and research: If there are envi- ronmental factors that influence sexual orientation, we do not yet know what they are.

Biology and Sexual Orientation The lack of evidence for environmental causes of homosexuality has motivated research- ers to explore possible biological influences. They have considered

• evidence of homosexuality in other species, • gay-straight brain differences, • genetics, and • prenatal hormones.

Same-Sex Attraction in Other Species In Boston’s Public Gardens, caretakers have solved the mystery of why a much-loved swan couple’s eggs never hatch. Both swans are female. In New York City’s Central Park Zoo, penguins Silo and Roy spent several years as devoted same-sex partners. At least occasional same - sex relations have been observed in several hundred species (Bagemihl, 1999). Grizzlies, gorillas, monkeys, flamingos, and owls are all on the long list. Among rams, for example, some 7 to 10 percent (to sheep-breeding ranchers, the “duds”) display same - sex attrac- tion by shunning ewes and seeking to mount other males (Perkins & Fitzgerald, 1997). Some degree of homosexual behavior seems a natural part of the animal world.

Gay-Straight Brain Differences Researcher Simon LeVay (1991) studied sections of the hypothalamus (a brain structure linked to emotion) taken from deceased heterosexual and homosexual people. As a gay man, LeVay wanted to do “something connected with my gay identity.” To avoid bias- ing the results, he did a blind study, without knowing which donors were gay or straight. After nine months of peering through his microscope at a hypothalamus cell cluster that seemed to come in different sizes, he consulted the donor records. The cell cluster was reliably larger in heterosexual men than in women and homosexual men. “I was almost in a state of shock,” LeVay said (1994). “I took a walk by myself on the cliffs over the ocean. I sat for half an hour just thinking what this might mean.”

It should not surprise us that brains differ with sexual orientation. Remember, every- thing psychological is simultaneously biological. But when did the brain difference begin? At conception? During childhood or adolescence? Did experience produce the difference? Or was it genes or prenatal hormones (or genes via prenatal hormones)?

LeVay does not view this cell cluster as an “on-off button” for sexual orientation. Rather, he believes it is an important part of a brain pathway that is active during sexual behavior. He agrees that sexual behavior patterns could influence the brain’s anatomy. (Neural pathways in our brain do grow stronger with use.) In fish, birds, rats, and humans, brain structures vary with experience—including sexual experience (Breedlove, 1997). But LeVay believes it more likely that brain anatomy influences sexual orientation. His hunch seems confirmed by the discovery of a similar difference found between the 7 to 10 percent of male sheep that display same - sex attraction and the 90+ percent attracted

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Juliet and Juliet Boston’s beloved swan couple, “Romeo and Juliet,” were discovered actually to be, as are many other animal part- ners, a same-sex pair.

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CHAPTER 5 GENDER AND SEXUALITY 181

to females (Larkin et al., 2002; Roselli et al., 2002, 2004). Moreover, such differences seem to develop soon after birth, perhaps even before birth (Rahman & Wilson, 2003).

Since LeVay’s discovery, other researchers have reported additional gay-straight brain activity differences. One is an area of the hypothalamus that governs sexual arousal (Savic et al., 2005). When straight women were given a whiff of a scent derived from men’s sweat (which contains traces of male hormones), this area became active. Gay men’s brains responded similarly to the men’s scent. Straight men’s brains did not. They showed the arousal response only to a female hormone sample. In a similar study, lesbi- ans’ responses differed from those of straight women (Kranz & Ishai, 2006; Martins et al., 2005).

Genetic Influences Three lines of evidence suggest a genetic influence on sexual orientation.

Family Studies “Homosexuality does appear to run in families,” noted Brian Mus- tanski and Michael Bailey (2003). Researchers have speculated about possible reasons why “gay genes” might persist in the human gene pool, given that same - sex couples cannot naturally reproduce. One possible answer is kin selection. Recall from Chapter 2 the evolutionary psychology reminder that many of our genes also reside in our bio- logical relatives. Perhaps, then, gay people’s genes live on through their supporting the survival and reproductive success of their nieces, nephews, and other relatives (who also carry many of the same genes). Gay men make generous uncles, suggests one study of Samoans (Vasey & VanderLaan, 2010).

An alternative “fertile females” theory suggests that maternal genetics may also be at work (Bocklandt et al., 2006). Homosexual men tend to have more homosexual relatives on their mother’s side than on their father’s (Camperio - Ciani et al., 2004, 2009; Zietsch et al., 2008). And the relatives on the mother’s side also produce more offspring than do the maternal relatives of heterosexual men. Perhaps the genes that dispose women to be strongly attracted to men, and therefore to have more children, also dispose some men to be attracted to men (LeVay, 2011).

Twin Studies Twin studies indicate that genes influence sexual orientation. Identical twins (who have identical genes) are somewhat more likely than fraternal twins (whose genes are not identical) to share a homosexual orientation (Alanko et al., 2010; Láng- ström et al., 2008, 2010). However, because sexual orientation differs in many identical twin pairs (especially female twins), other factors must also play a role.

Fruit Fly Studies Laboratory experiments on fruit flies have altered a single gene and changed the flies’ sexual orientation and behavior (Dickson, 2005). During courtship, females acted like males (pursuing other females) and males acted like females (Demir & Dickson, 2005). With humans, it’s likely that multiple genes, possibly in interaction with other influences, shape sexual orientation. In search of such genetic markers, one study financed by the U.S. National Institutes of Health is analyzing the genes of more than 1000 gay brothers.

Prenatal Influences Twins share not only genes, but also a prenatal environment. Two sets of findings indicate that the prenatal environment matters.

First, in humans, a critical period for brain development seems to fall between the middle of the second and fifth months after conception (Ellis & Ames, 1987; Gladue, 1990; Meyer - Bahlburg, 1995). Exposure to the hormone levels typically experienced by female fetuses during this period may predispose a person (female or male) to be attracted to males in later life. When pregnant sheep were injected with testosterone during a similar critical period, their female offspring later showed homosexual behavior (Money, 1987).

“Gay men simply don’t have the brain cells to be attracted to women.”

Simon LeVay, The Sexual Brain, 1993

“Studies indicate that male homosexuality is more likely to be transmitted from the mother’s side of the family.”

Robert Plomin, John DeFries, Gerald McClearn, and Michael Rutter,

Behavioral Genetics, 1997

“Modern scientific research indicates that sexual orientation is . . . partly determined by genetics, but more specifically by hormonal activity in the womb.”

Glenn Wilson and Qazi Rahman, Born Gay: The Psychobiology of Sex

Orientation, 2005

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182 CHAPTER 5 GENDER AND SEXUALITY

Second, the mother’s immune system may play a role in the develop- ment of sexual orientation. Men who have older brothers are somewhat more likely to be gay—about one-third more likely for each additional older brother (Blanchard, 1997, 2008; Bogaert, 2003). If the odds of homosexuality are roughly 2 percent among first sons, they would rise to nearly 3 percent among second sons, 4 percent for third sons, and so on for each additional older brother (see FIGURE 5.5). The reason for this curious effect—called the older-brother or fraternal birth-order effect—is unclear. But the explanation does seem biological. The effect does not occur among adopted brothers (Bogaert, 2006). Researchers suspect the mother’s immune system may have a defen-

sive response to substances produced by male fetuses. After each pregnancy with a male fetus, the maternal antibodies may become stronger and may prevent the fetal brain from developing in a typical male pattern.

Gay-Straight Trait Differences On several traits, gays and lesbians appear to fall midway between straight females and males (TABLE 5.1; see also LeVay, 2011; Rahman & Koerting, 2008). Gay men tend to be shorter and lighter than straight men—a difference that appears even at birth. Women in same-sex marriages were mostly heavier than average at birth (Bogaert, 2010; Frisch & Zdravkovic, 2010). Data from 20 studies have also revealed handedness differ- ences: Homosexual participants were 39 percent more likely to not be right - handed (Blanchard, 2008; Lalumière et al., 2000).

10%

2

8

6

4

0

Probability of homosexuality

1

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Right-handed

Non-right-handed

Table 5.1 Biological Correlates of Sexual Orientation

Gay-straight trait differences Sexual orientation is part of a package of traits. Studies—some in need of replication—indicate that homo- sexuals and heterosexuals differ in the following biological and behavioral traits:

• spatial abilities • gender nonconformity

• fingerprint ridge counts • age of onset of puberty in males

• auditory system development • male body size

• handedness • sleep length

• occupational preferences • physical aggression

• relative finger lengths • walking style

On average (the evidence is strongest for males), results for gays and lesbians fall between those of straight men and straight women. Three biological influences—brain, genetic, and prenatal—may contribute to these differences.

Brain differences • One hypothalamic cell cluster is smaller in women and gay men than in straight men.

• Anterior commissure is larger in gay men than in straight men.

• Gay men’s hypothalamus reacts as do straight women’s to the smell of sex - related hormones.

Genetic influences • Shared sexual orientation is higher among identical twins than among fraternal twins.

• Sexual attraction in fruit flies can be genetically manipulated.

• Male homosexuality often appears to be transmitted from the mother’s side of the family.

Prenatal influences • Altered prenatal hormone exposure may lead to homosexuality in humans and other animals.

• Men with several older biological brothers are more likely to be gay, possibly due to a maternal immune- system reaction.

Number of older br

FIGURE 5.5

The fraternal birth-order effect Researcher Ray Blanchard (2008) offered these approximate curves depicting a man’s likelihood of homosexuality as a function of his number of older brothers. This correlation has been found in several studies, but only among right-handed men (as about 9 in 10 men are).

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CHAPTER 5 GENDER AND SEXUALITY 183

FIGURE 5.6

Spatial abilities and sexual

orientation Which of the four figures can be rotated to match the target figure at the top? Straight males tend to find this an easier task than do straight females, with gays and lesbians intermediate. (From Rahman et al., 2003, with 60 people tested in each group.)

Answer: Figures a and d.

Gay-straight spatial abilities also differ. On mental rotation tasks such as the one illustrated in FIGURE 5.6, straight men tend to outscore straight women but the scores of gays and lesbians fall between those of straight men and women (Rah- man et al., 2003). But straight women and gays both outperform straight men at remembering objects’ spatial locations in tasks like those found in memory games (Hassan & Rahman, 2007).

* * * The consistency of the brain, genetic, and prenatal findings has swung the pendulum toward a biological explanation of sexual ori- entation (LeVay, 2011; Rahman & Koert- ing, 2008). Although “much remains to be discovered,” concludes Simon LeVay (2011, p. xvii), “the same processes that are involved in the biological development of our bodies and brains as male or female are also involved in the development of sexual orientation.”

RETRIEVE IT

• Which THREE of the following five factors have researchers found to have an effect on sexual orientation?

a. A domineering mother d. A distant or ineffectual father

b. Size of certain cell clusters in e. For men, having multiple older the hypothalamus biological brothers

c. Prenatal hormone exposure

ANSWERS: b, c, e

An Evolutionary Explanation of Human Sexuality

5-10: How might an evolutionary psychologist explain gender differences in sexuality and mating preferences?

Having faced many similar challenges throughout history, men and women have adapted in similar ways. Whether male or female, we eat the same foods, avoid the same predators, and perceive, learn, and remember similarly. It is only in those domains where we have faced differing adaptive challenges—most obviously in behaviors related to reproduction—that we differ, say evolutionary psychologists.

Gender Differences in Sexuality And differ we do. Consider women’s and men’s sex drives. Who desires more frequent sex? Thinks more about sex? Masturbates more often? Sacrifices more to gain sex? Initi- ates more sex—worldwide? The answers—Men, men, men, men, and men (Baumeister et al., 2001).No surprise, then, that in one BBC survey of more than 200,000 people in 53

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“There is no sound scientific evidence that sexual orientation can be changed.”

UK Royal College of Psychiatrists, 2009

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184 CHAPTER 5 GENDER AND SEXUALITY

nations, men everywhere more strongly agreed that “I have a strong sex drive” and “It doesn’t take much to get me sexually excited” (Lippa, 2008).

And there are other gender differences in sexuality (Hyde, 2005; Petersen & Hyde, 2010; Regan & Atkins, 2007). In a survey of 289,452 entering U.S. college students, 58 percent of men but only 34 percent of women agreed that “if two people really like each other, it’s all right for them to have sex even if they’ve known each other for a very short time” (Pryor et al., 2005). “I can imagine myself being comfortable and enjoying ‘casual’ sex with different partners,” agreed 48 percent of men and 12 percent of women in a survey of 4901 Australians (Bailey et al., 2000). Thus, university men in one study pre- ferred casual hook-ups, while women preferred planned dating (Bradshaw et al., 2010). Casual, impulsive sex has been most frequent among males with traditional masculine attitudes (Pleck et al., 1993).

In surveys, gay men (like straight men) report more interest in uncommitted sex, more responsiveness to visual sexual stimuli, and more concern with their partner’s physical attractiveness than do lesbian women (Bailey et al., 1994; Doyle, 2005; Schmitt, 2007).

In another survey of U.S. 18- to 59-year - olds, 48 percent of the women but only 25 percent of the men cited affection as a reason for first intercourse. And how often do they think about sex? “Every day” or “Several times a day,” acknowledged 19 percent of the women and 54 percent of the men (Laumann et al., 1994). Ditto for the sexual thoughts of Canadians: “Several times a day,” agreed 11 percent of women and 46 per- cent of men (Fischtein et al., 2007).

Natural Selection and Mating Preferences Evolutionary psychologists use natural selection to explain why—worldwide—women’s approach to sex is usually more relational, and men’s more recreational (Schmitt, 2005, 2007). Our natural yearnings are our genes’ way of reproducing themselves. “Humans are living fossils—collections of mechanisms produced by prior selection pressures,” said evolutionary psychologist David Buss (1995).

The explanation goes like this: Most women incubate and nurse one infant at a time. Men, however, can spread their genes by mating with many females. In our ancestral history, men most often sent their genes into the future by pairing widely, women by pairing wisely. Thus, heterosexual women prefer stick - around dads over likely cads. They are attracted to men who seem mature, dominant, bold, and affluent, with a potential for long- term mating and investment in their joint offspring (Gangestad & Simpson, 2000; Singh, 1995). In one study of hundreds of Welsh pedestrians, men rated a woman as equally attractive whether pictured at the wheel of a humble Ford Fiesta or a swanky Bentley. Women, however, found the man more attractive if he was in the luxury car (Dunn & Searle, 2010). From an evolutionary perspective, such attributes connote a man’s capacity to support and protect a family (Buss, 1996, 2009; Geary, 1998).

For heterosexual men, some desired traits, such as a woman’s youthful appearance, cross place and time (Buss, 1994). Evolutionary psychologists say that men who were drawn to healthy, fertile-appearing women—women with smooth skin and a youthful

shape suggesting many childbearing years to come—stood a better chance of send- ing their genes into the future. And sure enough, men feel most attracted to women

whose waists (thanks to their genes or their surgeons) are roughly a third nar- rower than their hips—a sign of future fertility (Perilloux et al., 2010).

Moreover, just as evolutionary psychology predicts, men are most attracted to women whose ages in the ancestral past (when ovulation began later than today) would have been associated

with peak fertility (Kenrick et al., 2009). Thus, teen boys are most excited by a woman several years older than themselves, mid-twenties men

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Steven Pinker, How the Mind Works, 1997

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CHAPTER 5 GENDER AND SEXUALITY 185

prefer women around their own age, and older men prefer younger women. This pattern consistently appears across European singles ads, Indian marital ads, and marriage records from North and South America, Africa, and the Philippines (Singh, 1993; Singh & Randall, 2007).

There is a principle at work here, say evolution- ary psychologists: Nature selects behaviors that increase the likelihood of sending one’s genes into the future. As mobile gene machines, we are designed to prefer what- ever worked for our ancestors in their environments. They were predisposed to act in ways that would leave grandchildren. Had they not been, we wouldn’t be here. And as carriers of their genetic legacy, we are similarly predisposed.

Critiquing the Evolutionary Perspective

5-11: What are the key criticisms of evolutionary explanations of human sexuality, and how do evolutionary psychologists respond?

Without disputing nature’s selection of traits that enhance gene survival, critics see some problems with evolutionary psychology’s explanation of our mating preferences. One is that evolutionary psychology starts with an effect (such as the gender sexuality difference) and works backwards to propose an explanation. They invite us to imagine a different result and reason backwards. If men were uniformly loyal to their mates, might we not reason that the children of these committed, supportive fathers would more often survive to pass on their father’s genes? Might not this bond with one woman also increase their otherwise slim odds of conceiving a child, while also preventing her from mating with competing men? Might not a ritualized bond—a marriage—also spare women from chronic male harassment? Such suggestions are, in fact, evolutionary explanations for why humans tend to pair off monogamously (Gray & Anderson, 2010). One can hardly lose at hindsight explanation, which is, said paleontologist Stephen Jay Gould (1997), mere “speculation [and] guesswork in the cocktail party mode.”

Some also worry about the social consequences of evolutionary psychology’s approach. Does it suggest that genes are destiny? Does it mean that any effort to remake society is useless (Rose, 1999)? Does it undercut moral responsibility (Buller, 2005, 2009)? Could it be used to rationalize “high - status men marrying a series of young, fertile women” (Looy, 2001)?

Others argue that evolutionary explanations blur the line between genetic legacy and social-cultural tradition. Cultural expectations also shape socialization. If men are social- ized to value lifelong commitment, they may sexually bond with one partner. If women are socialized to accept casual sex, they may willingly have sex with many partners.

Cultural expectations can bend the genders. Show Alice Eagly and Wendy Wood (1999; Eagly, 2009) a culture with gender inequality—where men are providers and women are homemakers—and they will show you a culture where men strongly desire youth and domestic skill in their potential mates, and where women seek status and earning potential in their mates. Show Eagly and Wood a culture with gender equality, and they will show you a culture with smaller gender differences in mate preferences.

Much of who we are is not hard - wired, agree evolutionary psychologists. “Evolution forcefully rejects a genetic determinism,” insists one research team (Confer et al., 2010). Evolutionary psychologists remind us that men and women, having faced similar adap- tive problems, are far more alike than different, and that humans have a great capacity for learning and social progress. Indeed, natural selection has prepared us to flexibly adjust and respond to varied environments, to adapt and survive, whether we live in igloos or tree houses.

The mating game Evolutionary psycholo- gists are not surprised that older men, and not just Harrison Ford, 70 (pictured here with his wife, Calista Flockhart, 48), often prefer younger women whose features suggest fertility.

Valerie Hache/AFP/Getty Images

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186 CHAPTER 5 GENDER AND SEXUALITY

San Diego Museum of Man, photograph by Rose Tyson

Evolutionary psychologists acknowledge struggling to explain some traits and behav- iors such as same-sex attraction and suicide

(Confer et al., 2010). But they ask us to remember evolutionary psychology’s test- able predictions. Evolutionary psycholo- gists predict, and have confirmed, that we tend to favor others to the extent that they share our genes or can later return our favors. They predict, and have con- firmed, that human memory should be well-suited to retaining survival-relevant

information (such as food locations, for which females exhibit superiority). They

predict, and have confirmed, various other male and female mating strategies. Evolutionary psychologists also remind us that

the study of how we came to be need not dictate how we ought to be. Understanding our tendencies some- times helps us overcome them.

RETRIEVE IT

• How do evolutionary psychologists explain gender differences in sexuality?

ANSWER: Evolutionary psychologists theorize that women have inherited their ancestors’ tendencies to be more cautious sexually, because of the challenges associated with incubating and nurturing offspring. Men have inherited an inclination to be more casual about sex, because their act of fathering requires a smaller investment.

• What are the three main criticisms of the evolutionary explanation of human sexuality?

ANSWER: (1) It starts with an effect and works backwards to propose an explanation. (2) Unethical and immoral men could use such explanations to rationalize their behavior toward women. (3) This explanation may overlook the effects of cultural expectations and socialization.

Reflections on Gender, Sexuality, and Nature–Nurture Interaction Our ancestral history helped form us as a species. Where there is variation, natural selec- tion, and heredity, there will be evolution. Our genes form us. This is a great truth about human nature.

But our culture and experiences also form us. If their genes and hormones predispose males to be more physically aggressive than females, culture may magnify this gender difference by encouraging males to be macho and females to be the kinder, gentler sex. If men are encouraged toward roles that demand physical power, and women toward more nurturing roles, each may act accordingly. By exhibiting the actions expected of those who fill such roles, they will shape their own traits. Presidents in time become more presidential, servants more servile. Gender roles similarly shape us.

Today, in many cultures, gender roles are converging. Brute strength is becoming increasingly irrelevant to power and status (think Bill Gates and Hillary Clinton). From 1960 into the next century, women soared from 6 percent to 50 percent of U.S. medi- cal students (AMA, 2010). In the mid-1960s, U.S. married women devoted seven times as many hours to housework as did their husbands; by 2003 this gap had shrunk to two times as many (Bianchi et al., 2000, 2006). Such swift changes signal that biology does not fix gender roles.

Culture matters As this exhibit at San Diego’s Museum of Man illustrates, children learn their culture. A baby’s foot can step into any culture.

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CHAPTER 5 GENDER AND SEXUALITY 187

If nature and nurture jointly form us, are we “nothing but” the product of nature and nurture? Are we rigidly determined?

We are the product of nature and nurture, but we are also an open system. Genes are all pervasive but not all powerful; people may defy their genetic bent to reproduce by electing celibacy. Culture, too, is all pervasive but not all powerful; people may defy peer pressures and do the opposite of the expected. To excuse our failings by blaming our nature and nurture is what philosopher - novelist Jean - Paul Sartre called “bad faith”— attributing responsibility for one’s fate to bad genes or bad influences.

In reality, we are both the creatures and the creators of our worlds. So many things about us—including our gender identity and mating behaviors—are the products of our genes and environments. Yet the future-shaping stream of causation runs through our present choices: Our decisions today design our environments tomorrow. Mind matters. The human environment is not like the weather—something that just happens. We are its architects. Our hopes, goals, and expectations influence our future. And that is what enables cultures to vary and to change.

CHAPTER REVIEW

Gender and Sexuality

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the chapter). Then turn to Appendix D, Complete Chapter Reviews, to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

Gender Development 5–1: What are some gender similarities and

differences in aggression, social power, and social connectedness?

5–2: How is our biological sex determined, and how do sex hormones influence prenatal and adolescent development?

5–3: How do gender roles and gender typing influence gender development?

Human Sexuality 5-4: How do hormones influence human sexual

motivation?

5-5: What is the human sexual response cycle, and how do sexual dysfunctions and paraphilias differ?

5-6: How can sexually transmitted infections be prevented?

5-7: How do external and imagined stimuli contribute to sexual arousal?

5-8: What factors influence teenagers’ sexual behaviors and use of contraceptives?

Sexual Orientation 5-9: What has research taught us about sexual

orientation?

LEARNING OBJECTIVES

ce human sexual

esponse cycle, and araphilias diffe

nn SeSeS xuxualalitityy do hormones influ

ion?

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188 CHAPTER 5 GENDER AND SEXUALITY

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

1. Females and males are very similar to each other. But one way they differ is that a. women are more physically aggressive than men. b. men are more democratic than women in their leadership

roles. c. girls tend to play in small groups, while boys tend to play

in large groups. d. women are more likely to commit suicide.

2. The fertilized egg will develop into a boy if it receives a chromosome from its father.

3. Primary sex characteristics relate to ; sec- ondary sex characteristics refer to . a. ejaculation; menarche b. breasts and facial hair; ovaries and testes c. emotional maturity; hormone surges d. reproductive organs; nonreproductive traits

4. On average, girls begin puberty at about the age of , boys at about the age of .

5. Those born with sexual anatomy that differs from “standard” male or female babies may be considered .

6. Gender role refers to our a. sense of being male or female. b. expectations about the way males and females should

behave. c. biological sex. d. unisex characteristics.

7. When children have developed a , they have a sense of being male or female.

8. A striking effect of hormonal changes on human sexual behavior is the

a. end of sexual desire in men over 60. b. sharp rise in sexual interest at puberty. c. decrease in women’s sexual desire at the time of

ovulation. d. increase in testosterone levels in castrated males.

9. In describing the sexual response cycle, Masters and Johnson noted that

a. a plateau phase follows orgasm. b. men experience a refractory period during which they

cannot experience orgasm. c. the feeling that accompanies orgasm is stronger in men

than in women. d. testosterone is released equally in women and men.

EXPERIENCE THE TESTING EFFECT

Test yourself on these terms by trying to write down the definition in your own words before flip- ping back to the referenced page to check your answer.

gender, p. 164

aggression, p. 164

X chromosome, p. 167

Y chromosome, p. 167

testosterone, p. 167

puberty, p. 167

primary sex characteristics, p. 167

secondary sex characteristics, p. 167

menarche [meh - NAR-key], p. 167

gender role, p. 169

role, p. 169

gender identity, p. 170

social learning theory, p. 170

gender typing, p. 170

transgender, p. 170

estrogens, p. 171

sexual response cycle, p. 173

refractory period, p. 173

sexual dysfunction, p. 173

AIDS (acquired immune deficiency syndrome), p. 174

sexual orientation, p. 178

TERMS AND CONCEPTS TO REMEMBER

An Evolutionary Explanation of Human Sexuality 5–10: How might an evolutionary psychologist explain

gender differences in sexuality and mating preferences?

5–11: What are the key criticisms of evolutionary explanations of human sexuality, and how do evolutionary psychologists respond?

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CHAPTER 5 GENDER AND SEXUALITY 189

10. What is the difference between sexual dysfunctions and paraphilias?

11. The use of condoms during sex (does/doesn’t) reduce the risk of getting HIV and (does/doesn’t) fully protect against skin- to-skin STIs.

12. An example of an external stimulus that might influence sexual behavior is

a. blood level of testosterone. b. the onset of puberty. c. a sexually explicit film. d. an erotic fantasy or dream.

13. Factors contributing to unplanned teen pregnancies include a. low levels of testosterone during adolescence. b. higher intelligence level. c. too much communication. d. alcohol use.

14. Evolutionary psychologists are most likely to focus on a. how we differ from one another. b. the social consequences of sexual behaviors. c. natural selection of the fittest adaptations. d. cultural expectations about the “right” ways for men and

women to behave.

15. Which factors have researchers thus far found to be unrelated to the development of our sexual orientation?

Find answers to these questions in Appendix E, in the back of the book.

Multiple-format self-tests and more may be found at www.worthpublishers.com/myers.

Experience more of the

TESTING EFFECT

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BASIC PRINCIPLES OF SENSATION AND PERCEPTION Transduction

Thresholds

THINKING CRITICALLY ABOUT: Can Subliminal Messages Control Our Behavior?

Sensory Adaptation

Perceptual Set

Context Effects

Motivation and Emotion

VISION The Stimulus Input: Light Energy

The Eye

Visual Information Processing

Color Vision

Visual Organization

Visual Interpretation

HEARING The Stimulus Input: Sound Waves

The Ear

THE OTHER SENSES Touch

Pain

Taste

Smell

Body Position and Movement

SENSORY INTERACTION THINKING CRITICALLY ABOUT: ESP— Perception Without Sensation?

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191

I have perfect vision,” explains my colleague, Heather Sellers, an acclaimed writer and teacher. Her vision may be fine, but there is a problem with her perception. In her

memoir, You Don’t Look Like Anyone I Know, Sellers (2010) tells of awkward moments resulting from her lifelong prosopagnosia—face blindness.

Her inability to recognize faces means that people sometimes perceive her as snobby or aloof. “Why did you walk past me?” a neighbor might later ask. Similar to those of us with hearing loss who fake hearing during trite social conversation, Sellers sometimes fakes recognition. She often smiles at people she passes, in case she knows them. Or she pretends to know the person with whom she is talking. (To avoid the stress associated with such perception failures, people

with serious hearing loss or with prosopagnosia often shy away from busy social situations.) But there is an upside: When encounter-

ing someone who previously irritated her, she typically won’t feel ill will, because she doesn’t recognize the person.

Unlike Sellers, most of us have a functioning area on the underside of our brain’s right hemisphere that helps us recognize a familiar human face as soon as we detect it—in only one-seventh of a second (Jacques & Rossion, 2006). This ability illustrates a broader principle. Nature’s sensory gifts enable each animal to obtain essential information. Some examples:

• Frogs, which feed on flying insects, have cells in their eyes that fire only in response to small, dark, moving objects. A frog could starve to death knee - deep in motionless flies. But let one zoom by and the frog’s “bug detector” cells snap awake.

• Male silkworm moths’ odor receptors can detect one-billionth of an ounce of sex attractant per second released by a female one mile away. That is why there continue to be silkworms.

• Human ears are most sensitive to sound frequencies that include human voices, especially a baby’s cry.

In this chapter, we’ll look more closely at what psychologists have learned about how we sense and perceive the world around us. We begin with some basic principles.

Sensation and Perception

CHAPTERRR6

In college, on a date at the Spaghetti Station, I returned from the bathroom and plunked myself down in the wrong booth, facing the wrong man. I remained unaware he was not my date even as my date (a stranger to me) accosted Wrong Booth Guy, and then stormed out of the Station. . . . I do not recognize myself in photos or videos. I can’t recog- nize my step-sons in the soccer pick-up line; I failed to determine which husband was mine at a party, in the mall, at the market.

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192 CHAPTER 6 SENSATION AND PERCEPTION

Basic Principles of Sensation and Perception

6-1: What are sensation and perception? What do we mean by bottom-up processing and top-down processing?

Sellers’ curious mix of “perfect vision” and face blindness illustrates the dis- tinction between sensation and perception. When she looks at a friend, her sensation is normal: Her sensory receptors detect the same information yours would, and her ner- vous system transmits that information to her brain. And her perception—the processes by which her brain organizes and interprets sensory input—is almost normal. Thus, she may recognize people from their hair, gait, voice, or particular physique, just not their face. Her experience is much like the struggle you or I would have trying to recognize a specific penguin.

In our everyday experiences, sensation and perception blend into one continuous process. In this chapter, we slow down that process to study its parts. In real life, our sensory and perceptual processes work together to help us decipher the world around us.

• Our bottom-up processing starts at the sensory receptors and works up to higher levels of processing.

• Our top-down processing constructs perceptions from the sensory input by drawing on our experience and expectations.

As our brain absorbs the information in FIGURE 6.1, bottom - up processing enables our sensory systems to detect the lines, angles, and colors that form the flower and leaves. Using top - down processing we interpret what our senses detect.

But how do we do it? How do we create meaning from the blizzard of sensory stimuli bombarding our bodies 24 hours a day? Meanwhile, in a silent, cushioned, inner world, our brain floats in utter darkness. By itself, it sees nothing. It hears nothing. It feels noth- ing. So, how does the world out there get in? To phrase the question scientifically: How do we construct our representations of the external world? How do a campfire’s flicker, crackle, and smoky scent activate neural connections? And how, from this living neuro- chemistry, do we create our conscious experience of the fire’s motion and temperature, its aroma and beauty? In search of answers to such questions, let’s look at some processes that cut across all our sensory systems.

Transduction

6-2: What three steps are basic to all our sensory systems?

Every second of every day, our sensory systems perform an amazing feat: They convert one form of energy into another. Vision processes light energy. Hear-

ing processes sound waves. All our senses

• receive sensory stimulation, often using specialized receptor cells. • transform that stimulation into neural impulses. • deliver the neural information to our brain.

The process of converting one form of energy into another that your brain can use is called transduction. Later in this chapter, we’ll focus on individual sensory systems. How do we see? Hear? Feel pain? Taste? Smell? Keep our balance? In each case, we’ll consider these three steps—receiving, transforming, and delivering the information to the brain.

First, though, let’s explore some strengths and weaknesses in our ability to detect and interpret stimuli in the vast sea of energy around us.

“Time’s fun when you’re having flies.”

Kermit the Frog

FIGURE 6.1

What’s going on here? Our sensory and perceptual processes work together to help us sort out the complex images, including the hidden couple in Sandro Del-Prete’s drawing, The Flowering of Love.

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sensation the process by which our sensory receptors and nervous system receive and rep- resent stimulus energies from our environment.

perception the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

bottom - up processing analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.

top - down processing information processing guided by higher - level mental pro- cesses, as when we construct perceptions draw- ing on our experience and expectations.

transduction conversion of one form of energy into another. In sensation, the trans- forming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brain can interpret.

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CHAPTER 6 SENSATION AND PERCEPTION 193

RETRIEVE IT

• What is the rough distinction between sensation and perception?

ANSWER: Sensation is the bottom-up process by which the physical sensory system receives and represents stimuli. Perception is the top-down mental process of organizing and interpreting sensory input.

Thresholds

6-3: What are the absolute and difference thresholds, and do stimuli below the absolute threshold have any influence on us?

At this moment, you and I are being struck by X - rays and radio waves, ultra- violet and infrared light, and sound waves of very high and very low frequencies. To all of these we are blind and deaf. Other animals with differing needs detect a world that lies beyond our experience. Migrating birds stay on course aided by an internal magnetic compass. Bats and dolphins locate prey using sonar, bouncing echoing sound off objects. Bees navigate on cloudy days by detecting invisible (to us) polarized light.

The shades on our own senses are open just a crack, allowing us a restricted awareness of this vast sea of energy. But for our needs, this is enough.

Absolute Thresholds To some kinds of stimuli we are exquisitely sensitive. Standing atop a mountain on an utterly dark, clear night, most of us could see a candle flame atop another mountain 30 miles away. We could feel the wing of a bee falling on our cheek. We could smell a single drop of perfume in a three - room apartment (Galanter, 1962).

German scientist and philosopher Gustav Fechner (1801–1887) studied our aware- ness of these faint stimuli and called them our absolute thresholds—the minimum stimulation necessary to detect a particular light, sound, pressure, taste, or odor 50 per- cent of the time. To test your absolute threshold for sounds, a hearing specialist would expose each of your ears to varying sound levels (FIGURE 6.2). For each tone, the test would define where half the time you could detect the sound and half the time you could not. That 50-50 point would define your absolute threshold.

Detecting a weak stimulus, or signal, depends not only on the signal’s strength (such as a hearing-test tone) but also on our psychological state—our experience, expecta- tions, motivation, and alertness. Signal detection theory predicts when we will detect weak signals (measured as our ratio of “hits” to “false alarms”). Lonely, anxious people at speed-dating events tend to respond with a low threshold and thus can be unselective

absolute threshold the minimum stimula- tion needed to detect a particular stimulus 50 percent of the time.

signal detection theory a theory pre- dicting how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness.

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Absolute threshold Can I detect this sound? An absolute threshold is the intensity at which a person can detect a stimulus half the time. Hearing tests locate these thresholds for various frequency levels.

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194 CHAPTER 6 SENSATION AND PERCEPTION ©

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“The heart has its reasons which reason does not know.”

Pascal, Pensées, 1670

in reaching out to potential dates (McClure et al., 2010). Signal detection theorists seek to understand why people respond differently to the same stimuli, and why the same person’s reactions vary as circumstances change.

RETRIEVE IT

• What three factors will make it more likely that you detect the arrival of a text message?

ANSWER: (1) You are expecting a text. (2) It is important that you see the text and respond. (3) You are alert.

Stimuli you cannot detect 50 percent of the time are subliminal—below your absolute threshold (see Figure 6.2). Under certain conditions, you can be affected by stimuli so weak that you don’t consciously notice them. An unnoticed image or word can reach your visual cortex and briefly prime your response to a later question. In a typical experiment, the image or word is quickly flashed, then replaced by a masking stimulus that interrupts the brain’s processing before conscious perception (Van den Bussche et al., 2009). One such experiment illustrates the deep reality of sexual orien- tation. Researchers asked people to gaze at the center of a screen, and then flashed a photo of a nude person to one side and a scrambled version of the photo to the other side (Jiang et al., 2006). Because the images were immediately masked by a colored checkerboard, the volunteers saw nothing but flashes of color and were unable to guess

where the nude had appeared. Then the researchers flashed a geometric figure to one side or the other, followed by the masking stimulus, and asked the volunteers to give the figure’s angle (FIGURE 6.3). Straight men’s answers were more accurate when the geometric figure appeared where a nude woman had appeared earlier. Gay men and straight women guessed more accurately when the geometric figure replaced a nude man. As other experiments confirm, we can evaluate a stimulus even when we are not consciously aware of it—and even when we are unaware of our evaluation (Ferguson & Zayas, 2009).

How do we feel or respond to what we do not know and cannot describe? An imperceptibly brief stimulus often triggers a weak response that can be detected by brain scanning (Blan- kenburg et al., 2003; Haynes & Rees, 2005, 2006). Only when a

stimulus triggers synchronized activity in several brain areas does it reach consciousness (Dehaene, 2009). Once again we see the dual-track mind at work: Much of our information processing occurs automatically, out of sight, off the radar screen of our conscious mind.

So can we be controlled by subliminal messages? For more on that question, see Thinking Critically About: Can Subliminal Messages Control Our Behavior?

Difference Thresholds To function effectively, we need absolute thresholds low enough to allow us to detect important sights, sounds, textures, tastes, and smells. We also need to detect small differences among stimuli. A musician must detect minute discrepancies when tuning an instrument. Parents must detect the sound of their own child’s voice amid other children’s voices. Even after living two years in Scotland, sheep baa’s all sound alike to my ears. But not to those of ewes, which I have observed streaking, after shear- ing, directly to the baa of their lamb amid the chorus of other distressed lambs.

The difference threshold (or the just noticeable difference [jnd]) is the minimum difference a person can detect between any two stimuli half the time. That difference threshold

FIGURE 6.3

The hidden mind After an image of a nude man or woman was flashed to one side or another, then masked before being perceived, people’s attention was unconsciously drawn to images in a way that reflected their sexual orientation (Jiang et al., 2006).

subliminal below one’s absolute threshold for conscious awareness.

priming the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.

difference threshold the minimum differ- ence between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference (or jnd).

Weber’s law the principle that, to be per- ceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount).

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CHAPTER 6 SENSATION AND PERCEPTION 195

increases with the size of the stimulus. Thus, if you add 1 ounce to a 10-ounce weight, you will detect the difference; add 1 ounce to a 100-ounce weight and you probably will not.

In the nineteenth century, Ernst Weber noted something so simple and so widely applicable that we still refer to it as Weber’s law. This law states that for an average person to perceive a difference, two stimuli must differ by a constant percentage (not a con- stant amount). The exact percentage varies, depending on the stimulus. Two lights, for example, must differ in intensity by 8 percent. Two objects must differ in weight by 2 per- cent. And two tones must differ in frequency by only 0.3 percent (Teghtsoonian, 1971).

Can Subliminal Messages Control Our Behavior?

Hoping to penetrate our unconscious, entre- preneurs offer audio and video programs to help us lose weight, stop smoking, or improve our memories. Soothing ocean sounds may mask messages we cannot consciously hear: “I am thin”; “Smoke tastes bad”; or “I do well on tests—I have total recall of information.” Such claims make two assumptions: (1) We can unconsciously sense subliminal (literally, “below threshold”) stimuli. (2) Without our awareness, these stimuli have extraordinary suggestive powers. Can we? Do they?

As we have seen, subliminal sensation is a fact. Remember that an “absolute” threshold is merely the point at which we can detect a stimulus half the time. At or slightly below this threshold, we will still detect the stimulus some of the time.

But does this mean that claims of subliminal persuasion are also facts? The near - consensus among researchers is No. The laboratory research reveals a subtle, fleeting effect. Prim- ing thirsty people with the subliminal word thirst might therefore, for a moment, make a thirst - quenching beverage ad more persua- sive (Strahan et al., 2002). Likewise, priming thirsty people with Lipton Ice Tea may increase their choosing the primed brand (Karremans et al., 2006; Veltkamp et al., 2011; Verwijmeren et al., 2011a,b). But the subliminal-message hucksters claim something different: a power- ful, enduring effect on behavior.

To test whether subliminal recordings have this enduring effect, Anthony Greenwald and his colleagues (1991, 1992) randomly assigned university students to listen daily for five weeks to commercial subliminal mes- sages claiming to improve either self - esteem or memory. But the researchers played a practical joke and switched half the labels. Some stu- dents who thought they were receiving affirma- tions of self - esteem were actually hearing the memory-enhancement message. Others got the self - esteem message but thought their memory was being recharged.

Were the recordings effective? Students’ test scores for self- esteem and memory, taken before and after the five weeks, revealed no effects. Yet the students perceived themselves receiving the benefits they expected. Those who thought they had heard a memory recording believed their memories had improved. Those who thought they had heard a self - esteem recording believed their self-esteem had grown. (Reading this research, one hears echoes of the testimonies that ooze from ads for such products. Some customers, having bought what is not supposed to be heard [and having indeed not heard it!] offer testimoni- als like, “I really know that your recordings were invaluable in reprogramming my mind.”)

Over a decade, Greenwald conducted 16 double - blind experiments evaluating sub- liminal self - help recordings. His results were

uniform: Not one of the recordings helped more than a placebo (Greenwald, 1992). And place- bos, you may remember, work only because we believe they will work.

THINKING CRITICALLY ABOUT:

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Subliminal persuasion? Although subliminally presented stimuli can subtly influ- ence people, experiments discount attempts at subliminal advertising and self -improvement. (The playful message here is not actually sub- liminal—because you can easily perceive it.)

The difference threshold In this computer- generated copy of the Twenty- third Psalm, each line of the typeface changes impercepti- bly. How many lines are required for you to experience a just notice- able difference?

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RETRIEVE IT

• Using sound as your example, illustrate the distinctions among these concepts: absolute thresholds, subliminal stimulation, and difference thresholds.

ANSWERS: Absolute threshold is the minimum stimulation needed to detect a particular sound (such as an approaching bike on the sidewalk behind us) 50 percent of the time. Subliminal stimulation happens when, without our awareness, our sensory system processes that sound (when it is below our absolute threshold). A difference threshold is the minimum difference needed to distinguish between two sounds.

Sensory Adaptation

6-4: What is the function of sensory adaptation?

Entering your neighbors’ living room, you smell a musty odor. You wonder how they can stand it, but within minutes you no longer notice it. Sensory

adaptation has come to your rescue. When we are constantly exposed to a stimulus that does not change, we become less aware of it because our nerve cells fire less frequently. (To experience sensory adaptation, move your watch up your wrist an inch: You will feel it—but only for a few moments.)

Why, then, if we stare at an object without flinching, does it not vanish from sight? Because, unnoticed by us, our eyes are always moving (FIGURE 6.4). This continual flitting from one spot to another ensures that stimulation on the eyes’ receptors continually changes.

What if we actually could stop our eyes from moving? Would sights seem to vanish, as odors do? To find out, psychologists have devised ingenious instruments that maintain a constant image on the eye’s inner surface. Imagine that we have fitted a volunteer, Mary, with one of these instruments—a miniature projector mounted on a contact lens (FIGURE 6.5a). When Mary’s eye moves, the image from the projector moves as well. So everywhere that Mary looks, the scene is sure to go.

If we project images through this instrument, what will Mary see? At first, she will see the complete image. But within a few seconds, as her sensory system begins to fatigue, things get weird. Bit by bit, the image vanishes, only to reappear and then disappear— often in fragments (Figure 6.5b).

Although sensory adaptation reduces our sensitivity to constant stimulation, it offers an important benefit: freedom to focus on informative changes in our environment with-

out being distracted by background chatter. Stinky or heavily perfumed people don’t notice their odor because, like you and me, they adapt to what’s con- stant and detect only change. Our sensory receptors are alert to novelty; bore them with repetition and they free our attention for more important things. We will see this principle again and again: We per- ceive the world not exactly as it is, but as it is useful for us to perceive it.

Our sensitivity to changing stimulation helps explain television’s attention -grabbing power. Cuts, edits, zooms, pans, sudden noises—all demand attention. The phenomenon is irresistible even to TV researchers. One noted that even during interesting conversations, “I cannot for the life of me stop from periodically glanc- ing over to the screen” (Tannenbaum, 2002).

Sensory adaptation and sensory thresholds are important ingredients in our perceptions of the world around us. Much of what we perceive comes not just from what’s “out there” but also from what’s behind our eyes and between our ears. Joh

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“We need above all to know about changes; no one wants or needs to be reminded 16 hours a day that his shoes are on.”

Neuroscientist David Hubel (1979)

FIGURE 6.4

The jumpy eye Our gaze jumps from one spot to another every third of a second or so, as eye-tracking equipment illustrated in this photograph of Edinburgh’s Princes Street Gardens (Henderson, 2007). The circles represent visual fixations, and the numbers indicate the time of fixation in milliseconds (300 milliseconds = three-tenths of a second).

sensory adaptation diminished sensitiv- ity as a consequence of constant stimulation.

perceptual set a mental predisposition to perceive one thing and not another.

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CHAPTER 6 SENSATION AND PERCEPTION 197

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RETRIEVE IT

• Why is it that after wearing shoes for a while, you cease to notice them (until questions like this draw your attention back to them)?

ANSWER: The shoes provide constant stimulation. Sensory adaptation allows us to focus on changing stimuli.

Perceptual Set

6-5: How do our expectations, contexts, emotions, and motivation influence our perceptions?

As everyone knows, to see is to believe. As we less fully appreciate, to believe is to see. Through experience, we come to expect certain results. Those expectations may give us a perceptual set, a set of mental tendencies and assumptions that affects (top - down) what we hear, taste, feel, and see.

Consider: Is the middle image in FIGURE 6.6 a man playing a saxophone or a wom- an’s face? What we see in such a drawing can be influenced by first looking at either of the two unambiguous versions (Boring, 1930).

Everyday examples of perceptual set abound. In 1972, a British newspaper published unretouched photographs of a “monster” in Scotland’s Loch Ness—“the most amazing pictures ever taken,” stated the paper. If this information creates in you the same expec- tations it did in most of the paper’s readers, you, too, will see the monster in the photo in FIGURE 6.7 on the next page. But when a skeptical researcher approached the photos with different expectations, he saw a curved tree trunk—as had others the day the photo was shot (Campbell, 1986). With this different perceptual set, you may now notice that the object is floating motionless, with no ripples in the water around it—hardly what we would expect of a lively monster.

FIGURE 6.5

Sensory adaptation: Now you see it,

now you don’t! (a) A projector mounted on a contact lens makes the projected image move with the eye. (b) Initially, the person sees the stabilized image, but soon she sees fragments fading and reappearing. (From “Stabilized images on the retina,” by R. M. Pritchard. Copyright © 1961 Scientific American, Inc. All rights reserved.)

FIGURE 6.6

Perceptual set Show a friend either the left or right image. Then show the center image and ask, “What do you see?” Whether your friend reports seeing a saxophonist or a woman’s face may depend on which of the other two drawings was viewed first. In each of those images, the meaning is clear, and it will establish perceptual expectations.

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198 CHAPTER 6 SENSATION AND PERCEPTION

Perceptual set can also affect what we hear. Consider the kindly airline pilot who, on a takeoff run, looked over at his depressed co - pilot and said, “Cheer up.” Expecting to hear the usual “Gear up,” the co-pilot promptly raised the wheels—before they left the ground (Reason & Mycielska, 1982).

Perceptual set similarly affects taste. One experiment invited bar patrons to sample free beer (Lee et al., 2006). When researchers added a few drops of vinegar to a brand- name beer, the tasters preferred it—unless they had been told they were drinking vin- egar-laced beer. Then they expected, and usually experienced, a worse taste. In another experiment, preschool children, by a 6-to-1 margin, thought french fries tasted better when served in a McDonald’s bag rather than a plain white bag (Robinson et al., 2007).

What determines our perceptual set? As Chapter 4 explained, through experience we form concepts, or schemas, that organize and interpret unfamiliar information. Our preexisting schemas for male saxophonists and women’s faces, for monsters and tree trunks, all influence how we interpret ambiguous sensations with top - down processing.

In everyday life, stereotypes about gender (another instance of perceptual set) can color perception. Without the obvious cues of pink or blue, people will struggle over whether to call the new baby “he” or “she.” But told an infant is “David,” people (espe- cially children) may perceive “him” as bigger and stronger than if the same infant is called “Diana” (Stern & Karraker, 1989). Some differences, it seems, exist merely in the eyes of their beholders.

Context Effects A given stimulus may trigger radically different perceptions, partly because of our differ- ing perceptual set, but also because of the immediate context. Some examples:

• Imagine hearing a noise interrupted by the words “eel is on the wagon.” Likely, you would actually perceive the first word as wheel. Given “eel is on the orange,” you

FIGURE 6.7

Believing is seeing What do you perceive? Is this Nessie, the Loch Ness monster, or a log?

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When shown the phrase Mary had a a little lamb many people perceive what they expect, and miss the repeated word. Did you?

“We hear and apprehend only what we already half know.”

Henry David Thoreau, Journal, 1860

Culture and context effects What is above the woman’s head? In one study, nearly all the East Africans who were questioned said the woman was balancing a metal box or can on her head and that the family was sitting under a tree. Westerners, for whom head-carrying is less common and corners and boxlike archi- tecture are more common, were more likely to perceive the family as being indoors, with the woman sitting under a window. (Adapted from Gregory & Gombrich, 1973.)

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CHAPTER 6 SENSATION AND PERCEPTION 199

would more likely hear peel. This curious phenomenon, discovered by Richard Warren, suggests that the brain can work backward in time to allow a later stimulus to determine how we perceive an earlier one. The context creates an expectation that, top - down, influences our perception (Grossberg, 1995).

• Does the pursuing monster in FIGURE 6.8 look aggressive? Does the identical pursued one seem frightened? If so, you are experi- encing a context effect.

• How tall is the shorter player in FIG- URE 6.9? Here again, context creates expectations.

FIGURE 6.8

The interplay between context

and emotional perception The context makes the pursuing monster look more aggressive than the pursued. It isn’t.

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Big and “little” The “little guy” shown here is actually a 6’9” former Hope College basketball center who would tower over most of us. But he seemed like a short player when matched in a semi-pro game against the world’s tallest basketball player at that time, 7’9” Sun Ming Ming from China.

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Motivation and Emotion Perceptions are also influenced, top-down, by our motivation and emotions.

Desired objects, such as a water bottle when thirsty, seem closer (Balcetis & Dunning, 2010). This perceptual bias energizes our going for it. Our motives also direct our percep- tion of ambiguous images (FIGURE 6.10).

When angry, people more often perceive neutral objects as guns (Baumann & DeSteno, 2010). Dennis Proffitt (2006a,b; Schnall et al., 2008) and others have dem- onstrated the power of emotions with other clever experiments showing that

• walking destinations look farther away to those fatigued by prior exercise. • a hill looks steeper to those who are wearing a heavy backpack or have

just been exposed to sad, heavy classical music rather than light, bouncy music. As with so many of life’s challenges, a hill also seems less steep to those with a friend beside them.

• a target seems farther away to those throwing a heavy rather than a light object at it.

“Ambiguity of form: Old and new” by G. H. Fisher, 1968, Perception and Psychophysics, 4, 189–192. Copyright 1968 by Psychonomic Society, Inc.

FIGURE 6.10

Ambiguous horse/

seal figure If motivated to perceive farm animals, about 7 in 10 people immediately perceived a horse. If motivated to perceive a sea animal, about 7 in 10 perceived a seal (Balcetis & Dunning, 2006).

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200 CHAPTER 6 SENSATION AND PERCEPTION

“When you’re hitting the ball, it comes at you looking like a grapefruit. When you’re not, it looks like a blackeyed pea.”

Former Major League Baseball player George Scott

Even a softball appears bigger when you are hitting well, observed Jessica Witt and Proffitt (2005), after asking players to choose a circle the size of the ball they had just hit well or poorly.

Emotions can also color our social perceptions. Spouses who feel loved and appreci- ated perceive less threat in stressful marital events—“He’s just having a bad day” (Murray et al., 2003). Professional referees, if told a soccer team has a history of aggressive behav- ior, will assign more penalty cards when watching videotaped fouls (Jones et al., 2002).

RETRIEVE IT

• In the context of sensation and perception, what does it mean to say that “believing is seeing”?

ANSWER: Because of perceptual set, our experiences, assumptions, and expectations sculpt our views of reality.

• Does perceptual set involve bottom-up or top-down processing? Why?

ANSWER: It involves top-down processing, drawing on our experiences, assumptions, and expectations.

Vision Our eyes receive light energy and transduce (transform) it into neural messages that our brain then processes into what we consciously see. How does such a taken - for - granted yet remarkable thing happen?

The Stimulus Input: Light Energy

6-6: What is the energy that we see as visible light?

When you look at a bright red tulip, what strikes your eyes is not particles of the color red but pulses of electromagnetic energy that your visual system

perceives as red. What we see as visible light is but a thin slice of the whole spectrum of electromagnetic energy, ranging from imperceptibly short gamma waves to the long waves of radio transmission (FIGURE 6.11). Other organisms are sensitive to differing portions of the spectrum. Bees, for instance, cannot see what we perceive as red but can see ultraviolet light.

Two physical characteristics of light help determine our sensory experience. Light’s wavelength—the distance from one wave peak to the next (FIGURE 6.12a)— determines its hue (the color we experience, such as a tulip’s red petals or green leaves). Intensity, the amount of energy in light waves (determined by a wave’s amplitude, or height), influences brightness (Figure 6.12b). To understand how we transform physical energy into color and meaning, we first need to understand vision’s window, the eye.

The Eye

6-7: How does the eye transform light energy into neural messages, and how do the eye and brain process that information?

Light enters the eye through the cornea, which protects the eye and bends light to provide focus (FIGURE 6.13). The light then passes through the pupil, a small adjustable opening surrounded by the iris, a colored muscle that controls the size of the pupil by dilating or constricting in response to light intensity and even to inner emotions. (When we’re feeling amorous, our telltale dilated pupils and dark eyes sub- tly signal our interest.) Each iris is so distinctive that an iris-scanning machine can confirm our identity.

wavelength the distance from the peak of one light or sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.

hue the dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth.

intensity the amount of energy in a light or sound wave, which we perceive as bright- ness or loudness, as determined by the wave’s amplitude.

retina the light - sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

accommodation the process by which the eye’s lens changes shape to focus near or far objects on the retina.

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CHAPTER 6 SENSATION AND PERCEPTION 201

Behind the pupil is a transparent lens that focuses incoming light rays into an image on the retina, a multilayered tissue on the eyeball’s sensitive inner surface. The lens focuses the rays by changing its curvature and thickness, in a process called accommodation.

For centuries, scientists knew that when an image of a candle passes through a small opening, it casts an inverted mirror image on a dark wall behind. If the image passing through the pupil casts this sort of upside - down image on the retina, as in Figure 6.13, how can we see the world right side up? Eventually, the answer became clear: The retina doesn’t “see” a whole image. Rather, its millions of receptor cells convert particles of light energy into neural impulses and forward those to the brain. There, the impulses are reassembled into a perceived, upright- seeming image.

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The wavelengths we see What we see as light is only a tiny slice of a wide spectrum of electromagnetic energy, which ranges from gamma rays as short as the diameter of an atom to radio waves over a mile long. The wavelengths visible to the human eye (shown enlarged) extend from the shorter waves of blue- violet light to the longer waves of red light.

FIGURE 6.13

The eye Light rays reflected from a candle pass through the cornea, pupil, and lens. The curvature and thickness of the lens change to bring nearby or distant objects into focus on the retina. Rays from the top of the candle strike the bottom of the retina, and those from the left side of the candle strike the right side of the retina. The candle’s image on the retina thus appears upside - down and reversed.

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The physical properties of waves (a) Waves vary in wavelength (the distance between successive peaks). Frequency, the number of complete wavelengths that can pass a point in a given time, depends on the wavelength. The shorter the wavelength, the higher the frequency. (b) Waves also vary in amplitude (the height from peak to trough). Wave amplitude determines the intensity of colors.

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202 CHAPTER 6 SENSATION AND PERCEPTION

Visual Information Processing If you could follow a single light-energy particle to the back of your eye, you would first make your way through the retina’s outer layer of cells to its buried receptor cells, the rods and cones (FIGURE 6.14). There, you would see the light energy trigger chemical changes that would spark neural signals, activating nearby bipolar cells. The bipolar cells in turn would activate the neighboring ganglion cells, whose axons twine together like the strands of a rope to form the optic nerve. That nerve will carry the information to your brain, where your thalamus stands ready to distribute the information. The optic nerve can send nearly 1 million messages at once through its nearly 1 million ganglion fibers. (The auditory nerve, which enables hearing, carries much less informa- tion through its mere 30,000 fibers.) We pay a small price for this eye-to-brain highway. Where the optic nerve leaves the eye, there are no receptor cells—creating a blind spot (FIGURE 6.15). Close one eye and you won’t see a black hole, however. Without seeking your approval, your brain fills in the hole.

RETRIEVE IT

• There are no receptor cells where the optic nerve leaves the eye. This creates a blind spot in your vision. To demonstrate, first close your left eye, look at the spot, and move the page to a distance from your face at which one of the cars disappears (which one do you predict it will be?). Repeat with your right eye closed—and note that now the other car disappears. Can you explain why?

ANSWER: Your blind spot is on the nose side of each retina, which means that objects to your right may fall onto the right eye’s blind spot. Objects to your left may fall on the left eye’s blind spot. The blind spot does not normally impair your vision, because your eyes are moving and because one eye catches what the other misses.

FIGURE 6.14

The retina’s reaction to light

LightLight

1

2

3

To the brain’s visual cortex via the thalamus

Light

Cross section of retina

Neural impulse

3. Bipolar cells then activate the ganglion cells, the axons of which converge to form the optic nerve. This nerve transmits information to the visual cortex (via the thalamus) in the brain.

1. Light entering eye triggers photochemical reaction in rods and cones at back of retina. 1

2 3

2. Chemical reaction in turn activates bipolar cells.

Optic nerve

Bipolar cell Bipolar cell

Ganglion cell Ganglion cell

Cone

Rod

FIGURE 6.15

The blind spot

rods retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond.

cones retinal receptor cells that are con- centrated near the center of the retina and that function in daylight or in well - lit conditions. The cones detect fine detail and give rise to color sensations.

optic nerve the nerve that carries neural impulses from the eye to the brain.

blind spot the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.

fovea the central focal point in the retina, around which the eye’s cones cluster.

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CHAPTER 6 SENSATION AND PERCEPTION 203

Table 6.1 Receptors in the Human Eye: Rod- Shaped Rods and Cone - Shaped Cones

Cones Rods