How Do Drugs Alter Consciousness? or How Do Infants and Children Develop Over Time?

PSYCHOLOGY IN YOUR LIFE

PSYCHOLOGY IN YOUR LIFE

SaRaH GRISON Parkland College

TOdd F. HEaTHERTON dartmouth College

MICHaEL S. GazzaNIGa University of California, Santa Barbara

nW. W. NORTON & COMPaNYNEW YORk • LONdON

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Editor: Sheri L. Snavely Electronic Media Editor: Patrick Shriner Developmental Editor for the First Edition: Susan Weisberg Developmental Editor, Project Editor, and Manuscript Editor for the Second Edition: Kurt Wildermuth Assistant Editor: Scott Sugarman Editorial Assistant: Eve Sanoussi Associate Media Editor: Stefani Wallace Media Project Editor: Penelope Lin Media Assistant: Alex Trivilino Marketing Manager: Lauren Winkler Production Manager: Sean Mintus Photo Editor: Patricia Marx Photo Researcher: Elyse Rieder Permissions Manager: Megan Jackson Permissions Clearer: Elizabeth Trammell Design Director: Rubina Yeh Designer: Faceout Studio Composition: codeMantra Manufacturing: Transcontinental Managing Editor, College: Marian Johnson Managing Editor, College Digital Media: Kim Yi

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Library of Congress Cataloging-in-Publication Data

Names: Grison, Sarah, author. | Heatherton, Todd F., author. | Gazzaniga, Michael S., author. Title: Psychology in your life / Sarah Grison, Todd F. Heatherton, Michael S. Gazzaniga. Description: Second edition. | New York: W. W. Norton & Company, 2017. | Includes bibliographical references and index. Identifiers: LCCN 2015024071 | ISBN 978-0-393-26515-6 (pbk.) Subjects: LCSH: Developmental psychology. | Psychology. Classification: LCC BF713.G75 2017 | DDC 150—dc23 LC record available at http://lccn.loc. gov/2015024071

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1 2 3 4 5 6 7 8 9 0

For all teachers who inspire

others, especially

Ken Kotovsky and Steve Tipper

With gratitude,

Sarah Heatherton and James Heatherton

Lilli, Emmy, Garth, Dante,

and Rebecca

SaRaH GRISON is Associate Professor of Psychology at Parkland College. She brings more than 20 years of psychology teaching experience to Psychology in Your Life. Sarah exam- ines how psychological research can be applied to teaching and learning. She teaches intro- ductory psychology every term and puts her laboratory and classroom research into practice to improve student learning and actively engage students. She has created and taught courses to support novice teachers in developing their skills. Sarah is a certified Teacher-Scholar who previously was recognized each year on the University of Illinois List of Excellent Teachers. She has won the University of Illinois Provost’s Initiative for Teaching Advancement Award and the Association for Psychological Science Award for Teaching and Public Understand- ing of Psychological Science. She is a member of the Association for Psychological Science; the American Educational Research Association; the International Mind, Brain, and Educa- tion Society; and the American Psychological Association (Division 2, Society for Teaching of Psychology).

TOdd F. HEaTHERTON is the Lincoln Filene Professor in Human Relations in the Department of Psychological and Brain Sciences at Dartmouth College. He teaches introductory psychology every year. He is associate editor of the Journal of Cognitive Neuroscience and serves on many editorial boards and grant review panels. He received the Award for Distinguished Service on Behalf of Social-Personality Phychology in 2005, was named to Thompson Reuters’ ISI HighlyCited for Social Sciences in 2010, and received the Carol and Ed Diener Award for Outstanding Mid-Career Contributions to Personality Phychology in 2011. He received the Petra Shattuck Award for Teaching Excellence from the Harvard Extension School in 1994, the McLane Fellowship from Dartmouth College in 1997, and the Friedman Family Fellowship from Dartmouth College in 2001. He is a fellow of many scientific societies, including the American Association for the Advance- ment of Science.

MICHaEL S. GazzaNIGa is Distinguished Professor and Director of the Sage Center for the Study of the Mind at the University of California, Santa Barbara. In his career, he has introduced thousands of students to psychology and cognitive neuroscience. He founded and presides over the Cognitive Neuroscience Institute and is founding editor-in-chief of the Journal of Cognitive Neuroscience. He is past president of the American Psychological Society and a member of the American Academy of Arts and Sciences, the Institute of Medicine, and the National Academy of Sciences. He has held positions at the University of California, Santa Barbara; New York University; the State University of New York, Stony Brook; Cornell Univer- sity Medical College; and the University of California, Davis. He has written many notable books, including, most recently, Tales from Both Sides of the Brain: A Life in Neuroscience.

ABoUT THE AUTHoRS

vii

CoNTENTS IN BRIEF

Preface for Teachers ...................................................................................................viii

Letter to Students ..................................................................................................... xviii

1. Introducing the World of Psychology ................................2 2. The Role of Biology in Psychology ..................................... 38 3. Consciousness ............................................................................................... 76 4. development across the Life Span ................................... 114 5. Sensation and Perception ............................................................ 154 6. Learning ................................................................................................................ 194 7. Memory ................................................................................................................. 230 8. Thinking and Intelligence ............................................................. 268 9. Motivation and Emotion ................................................................. 306 10. Sex, Gender, and Sexuality ......................................................... 342 11. Health and Well-Being.......................................................................382 12. Social Psychology ................................................................................... 420 13. Self and Personality ............................................................................. 458 14. Psychological disorders ................................................................ 496 15. Psychological Treatments ............................................................ 536

appendix a: analyzing data in

Psychological Research .................................................................................... A-1

appendix B: Quizzes ................................................................................................ B-1

Everyone who has taught introductory psychology remembers their “first time.” Most instructors have a humorous story about being handed the textbook just a few days before class began and being pointed in the direction of the classroom. We, the authors of Psychology in Your Life, certainly remem- ber our first experiences. One of us was in a hot and windowless attic teaching discussion sections at Carnegie Mellon University. Another one of us was trying to overcome the imposter syndrome, teaching at Harvard in a building named after William James. And yet another one of us was trying to hold the attention of 800 students at the University of California, Santa Barbara, right before the 1967 Summer of Love. Whether we started teaching as undergraduate students, doctoral students, or faculty, all of us were immediately hooked on the expe- rience. We are passionate about the field and about exposing students to the science of psychology as well as helping them learn just how relevant psychology

is to their everyday lives. Over the years, as we have gained experience as teachers,

researchers, and authors, we have come to realize a key truth about inspiring students to learn. This truth

is that learning is not a unitary process, nor is it an activity conducted alone by students.

Instead, learning results from three inter- connected factors: teachers teaching,

students learning, and continuous efforts to improve the skills of both

teachers and students. We created Psychology in Your

Life because we wanted a textbook and integrated support materials that supported excellence in all three of these aspects of educ ation. Even

more importantly, we wanted to develop tools that would really work.

Accordingly, we designed the book and  support materials based on the

latest psychological research about the pedagogical practices that facilitate teach-

ing, learning, and making improvements.

PREFACE FoR TEACHERS

viii    ■    PREFACE

TEACHING LEARNING

IMPROVING

PREFACE    ■    ix

Great Teaching Improves Learning Providing support to both teachers and students is more important than ever because both teachers and students are experiencing a “perfect storm” of chal- lenges. Teachers must teach more students in a wider variety of course formats, support learning in many different students, and figure out how to assess student learning. Often, we must achieve these goals with fewer resources, less support, and little training. While students can sometimes learn without teachers, great teaching improves student learning. All teachers, from the most experienced to the novice, can use a helping hand to support their students’ learning. Psychology in Your Life supports teachers in two main ways.

First, Teachers Have Easy access to Materials that Are Aligned with the 

Learning  Goals  They  Have  Chosen  for  Their  Students Teachers’ goals for their students differ, based on the school, the students, and the teachers’ philoso- phies about teaching and learning (Kang, 2008). For example, individual teachers choose which content goals to focus on and which student skills to help develop, including cognitive skills such as application, writing, critical thinking, or scien- tific thinking (American Psychological Association, 2013; Anderson, 2002; Dunn, Halonen, & Smith, 2009). When using the Psychology in Your Life support package, teachers can focus on the learning goals and skills that are most relevant for their students. They can then use the corresponding pedagogical resources. Our rich bank of tools draws on our combined 75 years of teaching introductory psychology, and we know these tools work because we have overseen their development. The resources we offer—Active Learning PowerPoint lecture slides, Demonstration Videos for Students, in-class activities, clicker questions, discussion topics, video clip suggestions, and more—are tagged in the online repository by chapter, section, and learning goal, so teachers can easily search for resources related to specific learning goals and skill development. What’s more, these resources have been designed to be used flexibly in either face-to-face or online learning environments.

Second,  Teachers  Receive  Support  at  All  Levels  of  Experience We remember the dread we felt when we began to teach with few or no support materials. In response, we created Teaching Videos. Filmed in Sarah Grison’s home office, these clips offer brief observations to less experienced teachers about the concepts that students tend to find challenging. In presenting strategies for overcoming these chal- lenges (Buskist & Groccia, 2012), our videos refer to specific pedagogical supports in the textbook as well as to resources in the instructor support materials. Mean- while, even as experienced teachers, we still find ourselves hunting for new ways to engagingly demonstrate concepts. To address this need, we created Demonstration Videos for Teachers. These clips provide step-by-step instructions for doing in-class demonstrations of 30 important concepts found in the textbook. Printed summaries describe the materials, including handouts, needed to perform the demonstrations.

active Engagement Improves Learning Many students face obstacles to learning. They may find it difficult to absorb complex information. They may simply never have been taught how to learn. Students also vary in their desire to learn as well as what motivates them to engage with material. In addition, students often have limited time and money, so they have to strategize about engaging with material effectively and efficiently. Psychology in Your Life encour- ages students in two main ways.

TEACHING

LEARNING

x    ■    PREFACE

First, the Book and Ebook Encourage Students to Engage in Active Reading 

Processes Successful learning is goal-directed (American Psychological Associa- tion, 2013; Toukuhama-Espinosa, 2011). For this reason, each section of each chapter of Psychology in Your Life starts with learning goals that indicate what students should learn in that section. With other textbooks, students may not actually do anything with such goals. Perhaps they highlight key words or reread text passages, but these activi- ties are not effective learning techniques (Dunlosky et al., 2013). To encourage active use of our learning goals, we have paired each learning goal with a reading activity. In writing answers to reading activities associated with learning goals, the students will begin to remember, understand, and apply the concepts. Teachers can collect the students’ answers for a grade or even just check that they are completed, because low- stakes writing assignments like these can help learning (Elbow & Sorcinelli, 2005).

Second,  the  Book  and  Ebook  Give  Students  Many  Different  Ways  to 

Actively  Work  with  the  Material  Learning is enhanced when we relate new information to what we already know and when we ask why a particular thing happens (Dunlosky, et al., 2013; Toukuhama-Espinosa, 2011). Throughout each chapter of Psychology in Your Life, students can engage with activities. These active learning features are the Has It Happened to You?, Try It Yourself, Being a Critical Consumer, Scientific Thinking, and Using Psychology in Your Life boxes. Some of the features reinforce the book’s content, some help foster critical thinking, and others help relate the book’s content and critical thinking to the students’ lives. All of these features will help students learn and apply the material.

Practice Makes Perfect Most students need to work with material to master it and to demonstrate

their learning. Using multiple tools to distribute learning over time will maximize student learning (Cepeda et al., 2006). Accordingly, Psychol- ogy in Your Life includes two main ways for students to practice with the material over time and to get feedback on their performance, which will

improve their learning.

First, Students Can Repeatedly Practice with the Material by Using 

the inQuizitive and ZAPS 2.0 interactive Learning Tools Repeated prac- tice improves learning (Dunlosky et al., 2013; Toukuhama-Espinosa, 2011). When students get rich feedback about their answers, their learning is further enhanced (Hattie & Timperley, 2007). InQuizitive is a formative, adaptive homework tool that provides students with different types of interactive questions so they can work with the concepts and receive feedback about their answers. Students who earn higher scores on homework tools of this kind tend to obtain higher scores on exams (Regan, 2015). In addition, ZAPS 2.0, the online, interactive psychology research labs, allow students to engage in activities that simulate psychological research from the perspective of the participant or the researcher. By using ZAPS 2.0, students will experience the scientific method for themselves and hone their scientific thinking skills. These tools are discussed in further detail below.

Second,  Students  Can  Test  Themselves  on  the  Concepts  in  Several 

Ways Students need fast and simple ways to quiz themselves on their learning immediately after reading material in a textbook. Repeated testing lets students reaccess remembered information. Such reaccessing enhances learning (Roediger & Karpicke, 2006) and promotes transfer of the information to new situations using the concepts (Carpenter, 2012). Accordingly, the textbook and the ebook provide an

IMPROVING

PREFACE    ■    xi

appendix of self-quizzes, with one for each chapter. The answers are given for all the questions, and each question is associated with a specific learning goal in the chapter, so students can easily see which goals they have and have not mastered, then return to the appropriate sections of the text to review material. Lastly, teach- ers have the option of providing short pre-lecture and post-lecture quizzes to their students from the Norton Coursepack, a bank of multiple-choice questions that can be easily housed in any learning management system. Indeed, research shows that pre-lecture quizzes have learning benefits, including improved scores on later exams (Narloch, Garbin, & Turnage, 2006).

Introducing the Second Edition of Psychology in Your Life Because Psychology in Your Life is informed by evidence-based principles that help teachers support student learning, we need to continually update the book and the teaching support materials to reflect new research findings. Our pedagogi- cal input comes from psychology teachers who are using the materials, including Sarah Grison and her colleagues at Parkland College. Guided by the latest under- standings of teaching, learning, and improving, the second edition of Psychology in Your Life has been updated in several important ways.

A New Chapter on Sex, Gender, and Sexuality In the past few years, we have seen extraordinary and rapid advances in our psychological understanding of what biological sex is, how we come to understand our gender identity, and how biological sex and gender identity differ from sexual orientation. Accordingly, our new chap- ter—Chapter 10, “Sex, Gender, and Sexuality”—presents the most recent psycho- logical research on these topics, especially with respect to the biological bases of sexual orientation. Our approach is simultaneously informative about concepts that students may be unfamiliar with and sensitive toward people who may personally identify with the material. We also help students connect with the material by relat- ing it to current events. In addition, all of the teaching support materials for the new chapter have been developed by the authors and other experienced teachers who teach this material regularly. After reading this chapter and working with the active learning materials, students should understand, among other things, why biological sex, gender, and sexual orientation are different concepts that exist on a continuum.

Every  Chapter  Has  Been  Revised  and  Updated Comments from review- ers, our teaching colleagues, and our students have helped us ensure that every chapter in the textbook is as accurate and compelling as possible. First, we added information on topics that are important in the field of psychology. Second, we cited the most recent psychological research for the topics discussed in each chap- ter. Third, we added active learning to two of the book’s pedagogical features: The Scientific Thinking and Being a Critical Consumer boxes now include questions for students to think about and answer, either as homework or while in class. Fourth, we worked to enhance student comprehension in some places by reorganizing the content, changing the phrasing, and/or redesigning the graphics. Fifth, we updated the references to popular culture to keep our discussions and images fresh. Finally, we revised the teaching support materials so they align perfectly with the changes in the textbook. As a result of these changes, this new edition of Psychology in Your Life provides both teachers and students with the best, most up-to date informa- tion on psychological research and current events related to psychology, along with excellent new interactive ways for students to engage with the material.

xii    ■    PREFACE

Here is a chapter-by-chapter list of notable changes in this second edition:

1. Introducing the World of Psychology

•  Added humanistic psychology as an influential psychological school of thought

•  Clarified the cycle of the scientific method to include information on how to do a literature review

2. The Role of Biology in Psychology

•  Added information about the electrical properties of the neuron and action potentials

•  Clarified what happens to neurotransmitters that don’t bind to dendritic receptors

•  Included information on hemispheric specialization

3. Consciousness •  Reorganized the information about

consciousness in split-brain patients •  Simplified the graphics related

to electrical activity in the brain during sleep

•  Updated information about the effects of drugs on consciousness to include clinical applications of certain drugs (such as MDMA for treatment of PTSD)

10. Sex, Gender, and Sexuality •  New!

11. Health and Well-Being •  Added new information about

health effects of e-cigarettes •  Added a section on health impacts

of sexually transmitted infections • Added information about positive

impacts of exercising more, quitting smoking, and practicing safer sex

12. Social Psychology •  Explained how group membership

influences competition and cooperation

•  Added new information about modern racism

•  Clarified the information about bystander apathy surrounding the Kitty Genovese story

4. Development Across the Lifespan

•  Made the chapter shorter, more relevant, and easier to digest

•  Created a Being a Critical Consumer feature exploring whether educational media helps infants learn to talk

•  Designed a figure for Kohlberg ’s levels of moral development

•  Added new research on how physical exercise can mediate cognitive decline in people as they age

5.  Sensation and Perception •  Changed content to ensure that

students understand wavelengths and how they differ from frequencies

•  Clarified the function of smell receptors in olfaction

•  Added information about the perception of pain according to gate control theory

6. Learning •  Included updated information

about the debate on what happened to “Little Albert,” the infant in John Watson’s classical conditioning research

•  Changed the Try It Yourself feature to help students practice using operant conditioning with a pet

•  Added examples of negative reinforcement that students are likely to have experienced

7. Memory •  Added information about taking

notes on laptops, which affects how students pay attention to and remember information from class

•  Clarified the research on how suggestibility affects memory

•  Included research on false memories to complete the section on memory distortion

8. Thinking and Intelligence •  Streamlined and clarified the

presentation of how we think about concepts

•  Updated the table that presents the various models of how we think about concepts

•  Created a new Using Psychology in Your Life feature about making major decisions

 9. Motivation and Emotion •  Reorganized parts of the chapter so

the first section focuses on theories of motivation and the second focuses on specific motivations

•  Added material on how grit helps people achieve long-term goals

•  Added a new figure on the biological motivations related to hunger

PREFACE    ■    xiii

inquizitive  Homework  Tool Research shows that repeatedly practicing with material promotes learning. As a major step toward helping students practice, we are delighted to offer InQuizitive with the new edition. This formative, adaptive homework tool is designed to motivate students to engage with the concepts in a gamelike environment. In particular, the tool provides interactive questions of many styles (drag and drop, matching, etc.) to encourage students to work with the material. The tool also provides formative feedback not just on the correctness of answers, but also on the thought processes that a student most likely got wrong, and it links students with the concepts in the ebook so they can check their understand- ing of ideas. Finally, the tool is formative because it adapts to any concepts a student got wrong to provide additional questions, and practice, on the topics. InQuizitive was designed based on psychological research about how students learn, and the tool has been tested in the classroom to obtain direct evidence of its impact on learn- ing and indirect evidence about students’ attitudes toward it. Because teachers can easily access the student data from InQuizitive, they can flexibly tailor their classes to provide support for the concepts that students find most challenging. New! ZAPS 2.0 For those teachers who place a priority on helping students under- stand psychology as a science, and the scientific method used in psychological research, we now offer the opportunity to use ZAPS 2.0. This tool gives students a taste of what psychological research is like by letting them engage with interesting online experi- ments in a hands-on fashion. Across over 20 core psychological concepts, students get the opportunity to act as a participant and as a researcher to create and gather data from these labs, explore results, and share their findings. To reach these goals, each interactive lab has four parts: a brief video introduction to a concept presented in the text, an experiment or experience in which the student generates data based on her responses, an analysis of the data generated by the student and peers, and an examination of the theory behind the concept. To support teachers using ZAPS 2.0, each lab includes an instructors’ kit with ideas about how best to align the lab with the content in Psychology in Your Life. The instructor’s kit also offers ideas and materials to help students use and learn from the data produced in the lab.

Using Evidence-Based Teaching and Learning to Improve Educational Experiences Psychology in Your Life provides a unique pedagogical system, supporting teach- ing skills and student learning while providing ways to get evidence about educa- tional outcomes. We have spent several years working hard to make this vision into a reality. Now we give the new and improved Psychology in Your Life to you, so that these tools might help support learning in your students, and so that students can learn from you in the best way possible.

13. Self and Personality •  Clarified the three aspects of the

reciprocal determinism theory of personality

•  Created a new figure showing how traits are best understood as a continuum ranging from very low to very high on certain characteristics

•  Changed the section on objective measures to focus primarily on self-report tools used to investigate personality, such as questionnaires

14. Psychological Disorders • Ensured the chapter is consistent

with changes made in DSM-5 • Clarified the graphics showing

depressed and elevated moods in bipolar disorders

15. Psychological Treatments • Added information about historical

approaches to the treatment of psychological disorders

• Included new approaches to treating bipolar disorders with antipsychotic drugs

• Clarified new research showing that use of higher doses of SSRIs are associated with suicide attempts in adolescents who have depression

xiv    ■    ACKNoWLEDGMENTS

ACKNoWLEDGMENTS

Like teaching and learning, writing a textbook and developing unique and inte- grated educational tools for teachers and students are joint efforts. Our work to support teachers and students in Psychology in Your Life has depended so much on the support that we received in the years we have been engrossed in this proj- ect. First, we wish to thank our families for their unwavering support. Our spouses and significant others have been incredibly understanding and generous when we repeatedly worked through family vacations. And our children and grandchildren have patiently waited for us to finish working on the days when they wanted to spend time with us. We are very grateful to each of you.

It has been our good fortune to have been joined by so many talented individ- uals during the process of developing and revising Psychology in Your Life. We are extremely grateful to our colleagues who lent their expertise in psychology to writing material for the textbook. Carrie V. Smith, at the University of Missis- sippi, wrote the Being a Critical Consumer features. She’s an excellent teacher, and her efforts will help train students to be educated consumers of information. Debra Mashek, at Harvey Mudd College, wrote the Using Psychology in Your Life features. Her engaging and insightful voice will help students use psychology to improve their own lives. We thank Beth Morling, at the University of Delaware, for her expert advice on our research methods coverage. Tasha R. Howe, at Humboldt State University, contributed material to our development chapter. We are very grateful to Ines Segert, at the University of Missouri, for offering advice about each chapter and checking the accuracy of the text, figures, captions, and InQuizitive questions. We are also very grateful to the faculty, graduate students, and under- graduates at the University of Illinois, Urbana-Champaign. Many of the teaching and learning principles we used in Psychology in Your Life were inspired by the teaching of Dr. Sandra Goss Lucas, who has spent many years training graduate students in pedagogical best practices. In addition, many of the teaching practices used in this book have been empirically tested with the undergraduate students in introductory psychology, who helped us learn more about what helped them learn and what did not.

Most importantly, we wish to thank all of the psychology teachers at Parkland College, and the graduate student teachers and researchers from the University of Illinois, Urbana-Champaign, for sharing with us their knowledge of psychological concepts and of evidence-based teaching and learning pedagogies. It is only with their expertise that we have been able to develop and update the materials to support teachers’ skills in the Interactive Instructor’s Guide and student learning in Norton Smartwork and in the Test Bank. In particular, Travis Sola, Crystal Carlson, Gene- vieve Henricks, Rachel Smallman, Angela Isaacs, and Lauren Bohn Gibson, we thank you. Your dedication to our mission, boundless energy, and drive for excellence are truly inspirational. Daniel Kolen, you are a fast learner about psychology, and

ACKNoWLEDGMENTS    ■    xv

your keen eye and production talent have perfected our video materials to support students and teachers. You are a true gem in your profession, and we are grateful to call you one of us—a member of “The Team.”

Reviewers  and  Advisors  for  Our  New  Chapter  on  Sex,  Gender,  and 

 Sexuality Recently there have been vast developments in the psychological understanding of biological sex, gender, and sexuality. In addition, these topics are incredibly relevant to students today. Given both of these facts, we wanted to create a chapter that both reflects the best scientific knowledge and will have a lasting impact on students. In achieving this goal, we worked closely with several research experts in the field and with teachers who have had extraordinary success in engaging students with this complex material. We thank all of these people, listed below, for their excellent guidance, which helped us create a chapter founded in psychological research and representing the most current thinking on the topics.

Paul Abramson, University of California, Los Angeles John H. Bickford Jr., University of Massachusetts Amherst Diana Ciesko, Valencia Community College Michael Dudley, Southern Illinois University, Edwardsville Sarah Estow, Guilford College Rebecca Gazzaniga, University of California, Santa Barbara Jerry Green, Tarrant County College District Marissa A. Harrison, Pennsylvania State University, Harrisburg Benetha Jackson, Angelina College Tyson Keiger, Utica College Marianne LaFrance, Yale University Sadie Leder-Elder, High Point University

Stefanie Mitchell, San Jacinto College Ronn Newby, Des Moines Area Community College Patricia Schiml, Wright State University Peggy Skinner, South Plains College Margot Underwood, Joliet Junior College Lisa Wade, Occidental College Rebecca Walker-Sands, Central Oregon Community College Christopher Warren, California State University, Long Beach Matthew Webster, Blinn College Glenda Williams, Lone Star College Andrea Zabel, Midland College

Focus Group Participants We were guided and advised by fun, insightful, and committed introductory psychology teachers who attended several focus groups in Chicago; Houston; Washington, D.C.; St. Pete Beach; and Reno. They all read chap- ters, gave advice about level and detail, and helped to hone the look, feel, and content of the book and support program. We extend a special thank you to Laura Hebert, at Angelina College, for consulting her class several times to help us choose the best possible title for the textbook. We also thank Gregg Gold, at Humboldt State, for his excellent accuracy checking of an early version of the learning chapter. And we extend a special thank you to the Washington, D.C., focus group members/Mike Gazzaniga lunch club for the lively discussion on teaching, split-brain research, and life in general.

Reviewers The chapters were thoroughly reviewed as they moved through the editorial and production process over two editions. Reviewers included star teach- ers who checked for issues such as level, detail, pacing, and readability, all of which support student comprehension. Reviewers also included experts who checked for scientific accuracy and helped us find the right balance of correctness, clarity, and conciseness. Our reviewers showed extraordinary attention to detail and under- standing of the student experience. We are grateful to all the reviewers listed here. Their efforts reflect a deep commitment to excellence in psychology and in teaching students about the importance and applicability of our field.

xvi    ■    ACKNoWLEDGMENTS

Paul Abramson, University of California, Los Angeles

Arthur Alguin, Santa Barbara City College

Carol Anderson, Bellevue College

Nicole Arduini–Van Hoose, Hudson Valley Community College

Michelle Bannoura, Hudson Valley Community College

Nicole Barbari, Chaffey College

Holly Beard, Midlands Technical College

Dan Bellack, Trident Technical College

Richard Bernstein, Broward College

John H. Bickford Jr., University of Massachusetts Amherst

David Biek, Middle Georgia State University

Carol Borden, Saint Cloud State University

Allison Burton-Chase, Albany College of Pharmacy and Health Sciences

Bernardo Carducci, Indiana University Southeast

Pamela Case, Richmond Community College

Diana Ciesko, Valencia Community College

Scott Cohn, Western State Colorado University Kevin Conner, Liberty University Barbara Corbisier, Blinn College Andrew Corr, Kirkwood Community College, Iowa City Campus Dale Doty, Monroe Community College Gina Dow, Denison College Michael Dudley, Southern Illinois University, Edwardsville Sarah Estow, Guilford College Laura Flewelling, Johnston Community College Shannon Gadbois, Brandon University Andrew C. Gallup, SUNY, College at Oneonta Rebecca Gazzaniga, University of California, Santa Barbara Gregg Gold, Humboldt State University Jeffrey Green, Virginia Commonwealth University Jerry Green, Tarrant County College District Christine L. Grela, McHenry County College

Christine Harrington, Middlesex County College Marissa A. Harrison, Pennsylvania State University,

Harrisburg

Laura Hebert, Angelina College

Byron Heidenreich, Illinois State University Carmon Hicks, Ivy Tech Community College Northeast

Tasha Howe, Humboldt State University

Karin Hu, City College of San Francisco

Sandra Hunt, College of Staten Island

Malgorzata Ilkowska, Georgia Institute of Technology Benetha Jackson, Angelina College

Mike James, Ivy Tech Community College Northeast

Mary Johannesen-Schmidt, Oakton Community College Jennifer Johnson, Bloomsburg University of Pennsylvania

Jeffrey Jourdan, Ivy Tech Community College Northeast Tyson Keiger, Utica College Deborah P. Kelley, Tyler Junior College Patricia Kemerer, Ivy Tech Community College Northeast Lynnel Kiely, Harold Washington College Andrew Kim, Citrus College Yuthika Kim, Oklahoma City Community College Karen Kwan, Salt Lake Community College Marianne LaFrance, Yale University Sadie Leder-Elder, High Point University Katie W. Lewis, Pensacola State College Sheryl Leytham, Grand View University Debbie Ma, California State University, Northridge Pam Marek, Kennesaw State University Diane Martichuski, University of Colorado Boulder Randall Martinez, Cypress College Daniel McConnell, University of Central Florida Matthias Mehl, University of Arizona Stefanie Mitchell, San Jacinto College Ronn Newby, Des Moines Area Community College Erikson Neilsan, University at Buffalo Victoria Noriega, University of Miami Arthur Olguin, Santa Barbara City College David Payne, Wallace Community College Jeffrey J. Pedroza, Santa Ana College Carin Rubenstein, Pima Community College Patricia Schiml, Wright State University Randi Shedlosky-Shoemaker, York College of Pennsylvania Aya Shigeto, Nova Southeastern University Matt Shively, Wright State University Staci Simmelink-Johnson, Walla Walla Community College Nancy Simpson, Trident Technical College Peggy Skinner, South Plains College Latishia Smith, Ivy Tech Community College Margot Underwood, Joliet Junior College Lisa Wade, Occidental College Rebecca Walker-Sands, Central Oregon Community College Christopher Warren, California State University, Long Beach Martha Weaver, Dallas Country Community College Marti Weaver, Eastfield College Matthew Webster, Blinn College Nambrath Rajkumari Wesley, Brookdale Community College John William “Jay” Wright, Washington State University Glenda Williams, Lone Star College Keith Williams, Oakland University Andrea Zabel, Midland College Anna Clare Zaborowski, San Jacinto College, Central

ACKNoWLEDGMENTS    ■    xvii

The  Norton  Team  To realize a vision, you must take a first step. For Psychol- ogy in Your Life, the first step was a leap of faith, when W. W. Norton & Co. saw the possibilities of what this project could bring to teachers and students. As the oldest and largest independent publishing company, Norton has created some of the best- respected and iconic books in modern times. The excellence of these works makes Norton stand out as a beacon among publishers. Because the company is wholly owned by its employees, the employees are the heart and soul of this excellence.

Psychology in Your Life exists because of the extraordinary contributions of so many people at Norton. At the top of the list is Sheri Snavely, the editor of Psychology in Your Life. When Sarah and Sheri first discussed this project, many publishing companies were interested in taking a new approach to developing evidence-based educational products. While representatives from many companies wanted to hear about this proj- ect, Sheri wanted to learn about it through experience. She asked to sit in on Sarah’s introductory psychology class. No one from another company had asked to do that, but Sheri needed to see if Sarah was a teacher who actually “walked the walk” of support- ing student learning in class. That hands-on approach enabled Sheri to see the value in the vision. Sheri’s leadership and guidance have provided a constant star to keep us oriented in the right direction. She has our utter gratitude, respect, and admiration.

One of our key goals for this textbook was providing appropriate, accurate, and engaging information about psychology while supporting students’ abilities to understand the material. The developmental editor for the second edition, Kurt Wildermuth, helped us make the text accessible while maintaining the integrity of the content. He then carried the chapters through the many stages from manu- script editing to publication. Kurt mentored us through these processes, and he should be knighted for his sage advice, expertise, and patience.

Most textbooks have media components. The new vision for the electronic media in Psychology in Your Life is the brainchild of Patrick Shriner, electronic media editor extraordinaire. Patrick’s expertise and creativity helped guide us in crafting many new tools to support teachers’ skills, including the development of the Interactive Instructor’s Guide and the creation of original Demonstration Videos for Students, Demonstration Videos for Teachers, and Teaching Videos. Patrick and the amaz- ing associate media editor, Stefani Wallace, worked tirelessly with us to design all aspects of the ebook; Integrated Instructor’s Guide; InQuizitive online formative, adaptive homework tool; and Test Bank around the core learning goals in the text- book. The end result of these long hours of joint work is something remarkable: media that is part of an integrated package, connected to all aspects of Psychology in Your Life. Behind the scenes, editorial assistant Eve Sanoussi, assistant editor Scott Sugarman, and media assistant Alex Trivilino ensured that these many processes went smoothly. Their intelligence and organizational abilities helped guide us through invigorating and informative focus groups with talented teachers, rigorous reviewing and accuracy checking, and assembling the media support package.

One of the greatest joys in developing Psychology in Your Life has been work- ing with Lauren Winkler, our energetic and creative marketing manager. Lauren helped us convert an abstract vision to an easily communicated reality. She has a natural instinct for explaining complex ideas in simple terms, and her attention to detail in pursuing this goal through two editions is unwavering. Norton’s sales managers, representatives, and specialists are truly invested in supporting teachers and students. Their expertise, insight, and mission focus make them extraordinary advocates for excellence in education.

Finally, we want to thank the teachers we have met at conferences and meetings, where we have exchanged ideas about challenges in teaching and how to address those challenges. By contributing to the ideas behind Psychology in Your Life, those teachers have become part of the extended Norton family.

xviii    ■    LETTER To STUDENTS

Welcome to introductory psychology! It seems like just yesterday when we, the authors of this textbook, began studying psychology. Those experiences opened up a whole new world of amazing facts and insights, exciting questions and investiga- tions. We hope that you experience this same excitement during your introduction to psychology. This book will help you along that path.

Psychology is everywhere, affecting every second of your life. Regardless of your goals—whether you plan to be a psychology major, pursue a different bachelor’s degree, get an associate’s degree, or earn a professional certificate—in this book and in your class you can learn information that will change your life for the better.

Learning about psychology can positively affect your life in three main ways. First, if you plan to study psychology, the content that you learn in this book will provide a solid foundation for success in later psychology courses. Second, what you will learn in this book and your class can influence your personal life. The concepts discussed here will help you know yourself better; understand your family members, friends, and people you encounter; and improve your relationships. Third, taking this class will help you develop academic skills. Many topics in psychology directly translate into skills that you can use to improve your studying. Look out especially for the discussions of attention, memory, and learning.

Of course, in order for you to get these benefits from this book and the class, you must engage in the learning process. In short, you need to perform activities that help you practice with the concepts. These simple tips will increase your active learning:

1.  Actively work with your teacher. Read the syllabus for your class. Meet with your teacher. Get to know your teacher’s goals for your learning—what the instructor believes students must do to succeed in the class.

2.  Actively read the textbook. The best time to read the book is a few days before going to class. The best way to read is not by merely taking in the words or highlighting important ones. How many times have you thought, “Wait—what did I just read?” Instead, make reading an active process by writing out answers to the reading activities at the start of each section of the book. Bring your answers to class, and ask questions about any topics that are unclear to you.

3.  Actively participate in class. Merely sitting in class does not ensure that you are learning! Instead, actively pay attention by working with the material. Take notes on what your teacher says, then ask for access to any visual materials the teacher uses (such as PowerPoint slides), and check your notes against your teachers’ materials after class. Always write out your own examples of the major ideas because doing so helps learning.

LETTER To STUDENTS

LETTER To STUDENTS    ■    xix

4.  Repeatedly practice with the material. You can practice with the concepts in several ways. For example, you should take the self-quiz for each chapter in Appendix B at the back of this book and check your answers. Also, view your teachers’ quizzes as opportunities to practice. If your teacher is using InQuizitive—the online formative, adaptive homework tool—then you should complete all the assigned activities. You will be amazed at how much you will learn!

5.  Practice good test-taking skills. Most of us get nervous about taking tests. However, with the right study strategy and a positive attitude, taking tests is not that bad! The most important thing to do is space your learning out through the term. As you read the book, practice with the concepts inside and outside class. This way, you maximize how memory works. Don’t cram your studying into one or two nights before a test. Not only is cramming a bad way to remember things, but it will reduce the amount of sleep you get, and (as you’ll learn later in this book) adequate sleep is vital for remember- ing material you study. In addition, think about each test as a challenge—for example, as a way to show what you know. Thinking of a test as a threat will only stress you out more. Try to get to the test early, relax, and think positive thoughts. As you read the questions carefully, underline the key parts of each one. Read every answer and map each one back onto what you underlined to see if that answer fits or not. By slowly and thoroughly processing informa- tion, you can calmly and clearly make your way through the test.

As writers, we hope that you enjoy reading this book. As researchers, we hope you come to appreciate how fascinating psychology is. And as teachers, we hope you understand how relevant this material is to your daily life. If you come away from this class thinking about psychology in your life, then we will have achieved a great goal. And if you might want to major in psychology, or even look toward a profession in the field, then we will feel lucky to have you among us.

Have fun! Learn things.

Sarah Grison    Todd F. Heatherton    Michael S. Gazzaniga

xx    ■    CoNTENTS

Preface for Teachers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv Letter to Students  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii

1 Introducing the World of Psychology . . . . . . . . . . 2 1.1 Why Is Psychology Important to You? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Psychology Explains our Mental Activity and Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Psychology Teaches Us to Think Critically . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

LEARNiNG TiP:  Developing Critical Thinking Skills  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Psychology Helps Us Succeed in School and at Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 USiNG PSyCHOLOGy iN yOUR LiFE:  How Can Psychology Help Me Study? . . . 9

1.2 What do Psychologists Investigate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Psychology originated in Philosophical Questions  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Psychologists Investigate the Conscious and Unconscious Mind  . . . . . . . . . . . . . . . . . . 11 Psychologists Explore Behavior and Mental Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.3 Who are Psychologists Today? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Psychologists Work Across Levels of Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Psychologists Investigate Many Different Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Psychologists Today Follow Strict Ethical Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1.4 How do Psychologists Conduct Research? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Psychologists Use the Scientific Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Descriptive Methods Describe What Is Happening  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

  SCiENTiFiC THiNkiNG:  The Hawthorne Effect  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Correlational Methods Test Associations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

LEARNiNG TiP:  Problems Determining Causality in Correlational Methods  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

  BEiNG A CRiTiCAL CONSUMER:  Does Spanking Cause Long-Term Harm? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Experimental Methods Test Causation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

LEARNiNG TiP:  Dependent and Independent Variables  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

CoNTENTS

CoNTENTS    ■    xxi

2 The Role of Biology in Psychology . . . . . . . . . . . . . . 38 2.1 How do Our Nervous Systems affect

Thinking and Behavior? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Neurons Are the Basic Units of our Nervous Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Action Potentials Allow Neurons to Communicate With Each other . . . . . . . . . . . 43

LEARNiNG TiP:  Communication From Presynaptic Neuron to Postsynaptic Neuron  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Neurotransmitters Influence our Mental Activity and Behavior  . . . . . . . . . . . . . . . . . . 46

2.2 How do the Parts of Our Brains Function? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Understanding of our Brains Has Developed over Time  . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 The Hindbrain and Midbrain House Basic Programs for our Survival . . . . . . . . . . . 52

LEARNiNG TiP:  Processing in the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Forebrain Subcortical Structures Control our Motivations and Emotions  . . . . 54 The Cerebral Cortex of the Forebrain Processes our Complex Mental Activity  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

  BEiNG A CRiTiCAL CONSUMER:  What Are the Facts About Brains and “Handedness”? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

2.3 How do Our Brains Communicate With Our Bodies? . . . . . . . . . . . . . 63 our Somatic Nervous System Detects Sensory Input and Responds . . . . . . . . . . . 63 our Autonomic Nervous System Regulates the Body Automatically . . . . . . . . . . . 64

LEARNiNG TiP:  Remembering the Autonomic Nervous System  . . . . . . . . . . . . . . . . . 65 The Endocrine System Affects our Behavior Through Hormones . . . . . . . . . . . . . . . 65

2.4 How do Nature and Nurture affect Our Brains? . . . . . . . . . . . . . . . . . . . . 67 Genes Affect our Thoughts and Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Genes Interact With Environment to Influence Us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Environment Changes our Brains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 USiNG PSyCHOLOGy iN yOUR LiFE:  How Can I overcome a Learning Disability and Succeed? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

3 Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 3.1 What does It Mean to Be Conscious? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Consciousness Is a Subjective Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 LEARNiNG TiP:  Understanding Subjectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

There Are Different Levels of Consciousness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Unconscious Processing Sometimes Affects Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Brain Activity Gives Rise to Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

  SCiENTiFiC THiNkiNG:  The Relationship Between Consciousness and Brain Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

3.2 How does Sleep affect Consciousness? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Sleep Is Part of the Normal Rhythm of Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Consciousness Changes During Sleep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

LEARNiNG TiP:  Understanding Brain Activity During Sleep . . . . . . . . . . . . . . . . . . . . . . . 90 People Dream While Sleeping   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Sleep Is an Adaptive Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Sleep Disorders Are Relatively Common Throughout Life . . . . . . . . . . . . . . . . . . . . . . . . . . 94 USiNG PSyCHOLOGy iN yOUR LiFE:  How Can I Develop Better Sleep Habits? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

  BEiNG A CRiTiCAL CONSUMER:  Is the Sleeping Brain Ever Really Asleep? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

3.3 What Is an altered State of Consciousness? . . . . . . . . . . . . . . . . . . . . . . . . . . 98 There Are Different Altered States of Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Hypnosis Can Produce Changes in Perception, Memory, and Action . . . . . . . . . . . 99 Meditation Affects Cognitive Processing and Brain Function . . . . . . . . . . . . . . . . . . . . . 101 Flow Activities Can Lead to Altered Consciousness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

3.4 How do drugs alter Consciousness? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 People Use—and Abuse—Many Psychoactive Drugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Addiction Has Physical and Psychological Aspects  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

4 development across the Life Span . . . . . . . . . . . . . 114 4.1 How do We develop in the Womb? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

Prenatal Development Includes Three Phases of Physical Growth . . . . . . . . . . . . . . . 117 Substances Affect Prenatal Development in All Three Domains . . . . . . . . . . . . . . . . . . 119

LEARNiNG TiP:  Types of Teratogens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

4.2 How do Infants and Children develop Over Time? . . . . . . . . . . . . . . . 121 Infants and Children Change Physically . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Infants and Children Change Socially and Emotionally . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

  SCiENTiFiC THiNkiNG:  Attachment Is Due to Providing Contact  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Infants and Children Change Cognitively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

LEARNiNG TiP:  Assimilation and Accommodation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Language Develops in an orderly Way  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

  BEiNG A CRiTiCAL CONSUMER:  Can My Baby Learn to Talk by Watching Educational Media? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

4.3 How do adolescents develop? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Adolescents Develop Physically . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Adolescents Develop Socially and Emotionally . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 Adolescents Develop Cognitively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 USiNG PSyCHOLOGy iN yOUR LiFE:  Bullying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

LEARNiNG TiP:  Applying Kohlberg’s Three Levels of Moral Development  . . 144

4.4 How do We develop in adulthood? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 our Bodies Change in Adulthood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Adults Develop Lifelong Social and Emotional Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 The Mental Abilities of Adults Begin to Decline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

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CoNTENTS    ■    xxiii

5 Sensation and Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 5.1 How do Sensation and Perception affect Us? . . . . . . . . . . . . . . . . . . . . . . 157

our Senses Detect Physical Stimuli, and our Brains Process Perception . . . . . 157 There Must Be a Certain Amount of a Stimulus for Us to Detect It . . . . . . . . . . . . 159

5.2 How do We See? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Sensory Receptors in our Eyes Detect Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 We Perceive Color Based on Physical Aspects of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 We Perceive objects by organizing Visual Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

LEARNiNG TiP:  Bottom-Up and Top-Down Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 When We Perceive Depth, We Can Locate objects in Space . . . . . . . . . . . . . . . . . . . . . 172 Cues in our Brains and in the World Allow Us to Perceive Motion . . . . . . . . . . . . . . 172

5.3 How do We Hear? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Auditory Receptors in our Ears Detect Sound Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 USiNG PSyCHOLOGy iN yOUR LiFE:  Hearing Deficiencies From Listening to Loud Music With Ear Buds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 We Perceive Sound Based on Physical Aspects of Sound Waves . . . . . . . . . . . . . . . 178

5.4 How Can We Taste and Smell? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 Receptors in our Taste Buds Detect Chemical Molecules . . . . . . . . . . . . . . . . . . . . . . . . . 180

  SCiENTiFiC THiNkiNG:  Infant Taste Preferences Affected by Mother’s Diet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 our olfactory Receptors Detect odorants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

BEiNG A CRiTiCAL CONSUMER:  Sniffing out the Truth About Smell and Memory Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

5.5 How do We Feel Touch and Pain? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Receptors in our Skin Detect Temperature and Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . 187 We Detect Pain in our Skin and Throughout the Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

LEARNiNG TiP:  Fast and Slow Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Internal Sensory Systems Help Us Function in Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

6 Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 6.1 What are the Three Ways We Learn? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196

We Learn From Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 We Learn in Three Ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

LEARNiNG TiP:  Types of Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 The Brain Changes During Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

6.2 How do We Learn by Classical Conditioning? . . . . . . . . . . . . . . . . . . . . . 200 Through Classical Conditioning, We Learn That Stimuli Are Related . . . . . . . . . 200

  SCiENTiFiC THiNkiNG:  Pavlov’s Experiments Reveal Learning by Classical Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202

LEARNiNG TiP:  Understanding Classical Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 Learning Varies in Classical Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 We Learn Fear Responses Through Classical Conditioning . . . . . . . . . . . . . . . . . . . . . . 206 Adaptation and Cognition Influence Classical Conditioning . . . . . . . . . . . . . . . . . . . . . 207

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6.3 How do We Learn by Operant Conditioning? . . . . . . . . . . . . . . . . . . . . . . . 210 Animals Learn Through the outcomes of Their Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Learning Varies in operant Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 Reinforcement and Punishment Influence operant Conditioning . . . . . . . . . . . . . . . 214

LEARNiNG TiP:  Four Types of Reinforcement and Punishment  . . . . . . . . . . . . . . . . . 215 LEARNiNG TiP:  Four Schedules of Reinforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

operant Conditioning Affects our Lives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 USiNG PSyCHOLOGy iN yOUR LiFE:  Can Behavior Modification Help You Exercise Regularly?  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Biology and Cognition Influence operant Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . 220

6.4 How do We Learn by Watching Others? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Three Ways We Learn Through Watching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

  SCiENTiFiC THiNkiNG:  Bandura’s Bobo Doll Studies Reveal observational Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Watching others Results in Cultural Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

  BEiNG A CRiTiCAL CONSUMER:  Does Watching Violent Media Cause Aggressive Behavior? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Biology Influences observational Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

7 Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 7.1 How do We acquire Memories? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

We Acquire Memories by Processing Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 Attention Allows Us to Encode a Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 Selective Attention Allows Us to Filter Unwanted Information . . . . . . . . . . . . . . . . . 235

  SCiENTiFiC THiNkiNG:  Change Blindness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236

7.2 How do We Maintain Memories Over Time? . . . . . . . . . . . . . . . . . . . . . . . . . 238 Sensory Storage Allows Us to Maintain Information Very Briefly . . . . . . . . . . . . . . . 238 Working Memory Allows Us to Actively Maintain Information in Short-Term Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 Long-Term Storage Allows Us to Maintain Memories Relatively Permanently . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 our Long-Term Storage Is organized Based on Meaning . . . . . . . . . . . . . . . . . . . . . . . . . 245

7.3 What are Our different Long-Term Storage Systems? . . . . . . . 247 LEARNiNG TiP:  Remembering the Types of Memory in

Long-Term Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 our Explicit Memories Involve Conscious Effort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 our Implicit Memories Function Without Conscious Effort . . . . . . . . . . . . . . . . . . . . . . . 251 Prospective Memory Lets Us Remember to Do Something . . . . . . . . . . . . . . . . . . . . . . 252 Memory Is Processed by Several Regions of our Brains . . . . . . . . . . . . . . . . . . . . . . . . . . 253

  BEiNG A CRiTiCAL CONSUMER:  Can That Memory Be Erased? . . . . . . . . . . . . . . . . 255

7.4 How do We access Our Memories? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 Retrieval Cues Help Us Access our Memories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

LEARNiNG TiP:  Remembering the Ways We Access Stored Memories . . . . . . . 257 We Forget Some of our Memories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 USiNG PSyCHOLOGy iN yOUR LiFE:  How Can I Remember Information for Exams? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 our Unwanted Memories May Persist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

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our Memories Can Be Distorted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266

8 Thinking and Intelligence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 8.1 What Is Thinking? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270

Thinking Is the Manipulation of Mental Representations . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Thinking Depends on Categorization of Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

  SCiENTiFiC THiNkiNG:  Preschoolers’ Stereotypes About Adult Drinking and Smoking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

8.2 How do We Make decisions and Solve Problems? . . . . . . . . . . . . . . . 277 How We Think Biases Decision Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 We Solve Problems to Achieve Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 USiNG PSyCHOLOGy iN yOUR LiFE:  How Can I Be Satisfied with Big Decisions? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282 We overcome obstacles to Solve Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

8.3 What Is Intelligence? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 one General Factor May Underlie Intelligence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 There May Be Multiple Aspects of Intelligence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

  BEiNG A CRiTiCAL CONSUMER:  Are Criminals Less Intelligent Than other People? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292 Intelligence Is a Result of Genes and Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292

8.4 How do We Measure Intelligence? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 Intelligence Is Assessed With Psychometric Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

LEARNiNG TiP:  Validity and Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Intelligence Is Associated With Cognitive Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 Many Factors Determine Group Differences in Intelligence . . . . . . . . . . . . . . . . . . . . . . . 301

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304

9 Motivation and Emotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 9.1 What Motivates Our Behavior? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308

Many Factors Influence Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309 Some Behaviors Are Motivated for Their own Sake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

9.2 What Motivates Eating, the Need to Belong, and the Need for achievement? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Many Biological Systems Motivate Eating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316

LEARNiNG TiP:  Biological Mechanisms That Motivate Eating . . . . . . . . . . . . . . . . . . . . 317 Eating Is Influenced by Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318 We Have a Need to Belong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 We Have a Need to Achieve Long-Term Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 USiNG PSyCHOLOGy iN yOUR LiFE: How Can You Satisfy a Need to Belong? . . . 321

9.3 How do We Experience Emotions? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324 There Are Three Major Theories of Emotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325

LEARNiNG TiP:  Three Theories of Emotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326 Both Body and Brain Are Important for Emotion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

  BEiNG A CRiTiCAL CONSUMER:  Human Lie Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 We Regulate our Emotional States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331

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9.4 How do Emotions affect Us? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 We Interpret Emotions in Facial Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

  SCiENTiFiC THiNkiNG:  Facial Expressions Across Cultures . . . . . . . . . . . . . . . . . . . . . 335 our Display of Emotion Varies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336 Emotions Influence our Thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337 Emotions Strengthen our Interpersonal Relations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340

10 Sex, Gender, and Sexuality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 10.1 How does Biology Make Us Male or Female? . . . . . . . . . . . . . . . . . . . . . . . 344

Genetics and Hormones Influence Biological Sex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345 LEARNiNG TiP:  Five Aspects of Biological Sex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

Biological Sex Is Also Reflected in our Brains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 Biological Sex Is Not Always Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350

10.2 Why do We act Masculine or Feminine? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352 We Create Mental Categories of What Is Masculine and What Is Feminine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353 Gender Roles Affect our Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

  BEiNG A CRiTiCAL CONSUMER:  Why Are There Blue and Pink Toy Aisles? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356 Gender Identity Also Affects our Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358

LEARNiNG TiP:  Gender Schemas Include Information About Gender Roles and Gender Identity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 People Vary in Gender Identity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

10.3 How do We Vary in Sexual Orientation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362 We Vary in Sexual orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362 Biology Seems to Influence the Development of Sexual orientation . . . . . . . . . 365

LEARNiNG TiP:  Four Biological Contributions to Sexual orientation . . . . . . . . . 366   SCiENTiFiC THiNkiNG:  Fraternal Birth order Effect May

Explain Why Later-Born Males Are More Likely to Be Gay . . . . . . . . . . . . . . . . . . . . . . . 368

10.4 What Motivates Us to Have Sexual Relations (or Not to)? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 Biology Influences our Motivation for Sexual Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 Environmental Context Influences our Motivation for Sexual Activity . . . . . . . . 373 USiNG PSyCHOLOGy iN yOUR LiFE:  Changes in Sexual Desire and Sexual Activity over the Lifespan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374 Individual Differences Influence our Motivation for Sexual Activity . . . . . . . . . . . 376

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380

11 Health and Well-Being . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382 11.1 What affects Our Health? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384

Biology, Psychology, and Social Factors Influence Health . . . . . . . . . . . . . . . . . . . . . . . . 384 obesity Has Many Health Consequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386 Sexually Transmitted Infections Can Be Prevented by Practicing Safer Sex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392 Smoking Is Dangerous to Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 Exercise Has Numerous Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398

CoNTENTS    ■    xxvii

11.2 How does Stress affect Our Health? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 Stressors Have a Negative Impact on Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399

LEARNiNG TiP:  Stressors, Responses, and Mediating Factors . . . . . . . . . . . . . . . . . 400 We Have Several Responses to Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402

  SCiENTiFiC THiNkiNG:  Stress and the Immune System . . . . . . . . . . . . . . . . . . . . . . . . . . . 403

11.3 What Changes the Impact of Stressors? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 Personality Influences How Stress Affects Us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406 Coping Mediates the Effects of Stressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408 USiNG PSyCHOLOGy iN yOUR LiFE:  Reducing Exam Anxiety . . . . . . . . . . . . . . . . . . . 410

  BEiNG A CRiTiCAL CONSUMER:  Can Pets Help Reduce Stress? . . . . . . . . . . . . . . . . . . 411

11.4 Can a Positive attitude keep Us Healthy? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412 Positive Psychology Emphasizes Well-Being . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412 Social Support Is Associated With Good Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414 Several Strategies Can Help Us Stay Healthy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418

12 Social Psychology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420 12.1 How do We Think about Other People? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422

We Make Snap Judgments About People . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423 We Make Attributions About other People . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424

LEARNiNG TiP:  Attributions and the Actor/observer Bias . . . . . . . . . . . . . . . . . . . . . . . 425 We Tend to Stereotype other People . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425 Stereotypes Can Make Us Feel and Act Certain Ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426

12.2 How do Our attitudes affect Us? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430 Simple and Complex Attitudes Affect our Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430 We Form Attitudes Through Experience and Socialization . . . . . . . . . . . . . . . . . . . . . . . 431 Both Explicit and Implicit Attitudes Affect Us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432 Discrepancies Between Attitudes and Behavior Lead to Dissonance . . . . . . . . . 433

LEARNiNG TiP:  Cognitive Dissonance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 our Attitudes Can Be Changed Through Persuasion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434

12.3 How do Other People Influence Us?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 Groups Affect Individual Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 We Conform to the Expectations of others . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439 We Comply With the Requests of others . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440

  BEiNG A CRiTiCAL CONSUMER:  The Name Remembrance Effect . . . . . . . . . . . . . . 441 We obey People Who Have Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442

  SCiENTiFiC THiNkiNG:  Milgram’s Shock Experiments on obedience . . . . . . . . 443 We Sometimes Hurt Each other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444 We Help Each other . . . Sometimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446

12.4 How do We develop Strong Relationships? . . . . . . . . . . . . . . . . . . . . . . . . . 449 Situations and Personalities Affect our Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449 Love Is a Key Part of Romantic Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 USiNG PSyCHOLOGy iN yOUR LiFE:  overlooking Flaws to Have a Great Romantic Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 454

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456

xxviii    ■    CoNTENTS

13 Self and Personality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458 13.1 How do We know Ourselves? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461

our Sense of Self Is Who We Believe We Are . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 We Try to Maintain a Positive Sense of Self . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465 our Sense of Self Is Influenced by Cultural Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467

  BEiNG A CRiTiCAL CONSUMER:  Does My Culture Shape My Self-Esteem? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468

13.2 How Can We Understand Personality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469 Psychodynamic Theory Emphasizes Unconscious Conflicts . . . . . . . . . . . . . . . . . . . . . . 471

LEARNiNG TiP:  Id, Ego, and Superego . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473 Humanistic Approaches Emphasize Goodness in People . . . . . . . . . . . . . . . . . . . . . . . . . 474 Social Cognitive Approaches Focus on How Thoughts Shape Personality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 Trait Approaches Describe Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478

LEARNiNG TiP:  Remembering the Big Five . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478   SCiENTiFiC THiNkiNG:  Gosling’s Study of Personality in Animals . . . . . . . . . . . . . 479

13.3 How does Biology affect Personality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481 Personality Is Affected by Genes and the Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481 our Temperaments Are Innate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483 Personality Is Influenced by Physiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484 Personality Stability Is Influenced by Biology and Situation . . . . . . . . . . . . . . . . . . . . . 485

13.4 How do We assess Personality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487 Several Methods Are Used to Assess Personality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 488 Behavior Is Influenced by Personality and Situations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 490 USiNG PSyCHOLOGy iN yOUR LiFE:  Do Personalities Matter in Roommate Relationships? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491 There Are Cultural and Sex Differences in Personality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494

14 Psychological disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 496 14.1 What Is a Psychological disorder?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498

Disorders Interfere With our Lives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499 LEARNiNG TiP:  Limitations of the Criteria for Disordered

Emotions, Thoughts, and Behaviors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 There Are Several Causes of Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501 Disordered Thoughts and Behavior Can Be Assessed and Categorized . . . . . 502

14.2 How do People Experience disorders of Emotion? . . . . . . . . . . . . 505 Anxiety Disorders Make People Fearful and Tense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505 Unwanted Thoughts Create Fear in obsessive-Compulsive Disorder . . . . . . . . . 508

  SCiENTiFiC THiNkiNG:  Inhibition and Social Anxiety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509 Posttraumatic Stress Disorder Results From Trauma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510 Depressive Disorders Are Common . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511 Bipolar Disorders Involve Mania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514 USiNG PSyCHOLOGy iN yOUR LiFE:  What to Do if a Person Might Be Thinking of Suicide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515

14.3 How do People Experience disorders of Thought? . . . . . . . . . . . . . 518 Schizophrenia Is a Psychotic Disorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518

CoNTENTS    ■    xxix

14.4 How do People Experience disorders of Self? . . . . . . . . . . . . . . . . . . . . 523 Personality Disorders Are Maladaptive Ways of Relating to the World . . . . . . 523 Dissociative Disorders Involve Disruptions in one’s Sense of Self. . . . . . . . . . . . . . 526

  BEiNG A CRiTiCAL CONSUMER:  Do Mental Illness and Violent Crime Go Together?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528

14.5 What disorders affect Children? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 529 Autism Spectrum Disorder Involves Social Deficits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 529 Attention-Deficit/Hyperactivity Disorder Is Common in Childhood . . . . . . . . . . . 532

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534

15 Psychological Treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 536 15.1 How are Psychological disorders Treated? . . . . . . . . . . . . . . . . . . . . . . . . . . 538

Psychotherapy Is Based on Psychological Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540 Biological Therapies Are Effective for Certain Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . 544 Scientific Evidence Indicates Which Treatments Are Safe and Effective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 546 Various Providers Assist in Treatment for Psychological Disorders . . . . . . . . . . . . 547 USiNG PSyCHOLOGy iN yOUR LiFE:  How Do I Find a Provider Who Can Help Me? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549

15.2 What are Effective Treatments for Common disorders? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 550 Anxiety and obsessive-Compulsive Disorders Are Best Treated With Cognitive-Behavioral Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 Many Effective Treatments Are Available for Depressive Disorders . . . . . . . . . . . 556

  BEiNG A CRiTiCAL CONSUMER:  Consuming Antidepressant Advertising . . . 557   SCiENTiFiC THiNkiNG:  Mayberg’s Study of Deep Brain

Stimulation for Depression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 Psychotropic Medications Are Most Effective for Bipolar Disorders . . . . . . . . . . 560 Antipsychotic Medications Are Superior Treatments for Schizophrenia . . . . . 561

15.3 Can Personality disorders Be Treated? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563 Dialectical Behavior Therapy Is Most Successful for Borderline Personality Disorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564 Antisocial Personality Disorder Is Extremely Difficult to Treat . . . . . . . . . . . . . . . . . . 565

15.4 How Can disorders Be Treated in Children and adolescents? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567 Using Medication to Treat Depression in Adolescents Is Controversial . . . . . . 567 Children With ADHD Can Benefit From Various Approaches . . . . . . . . . . . . . . . . . . . 570 Children With Autism Spectrum Disorder Benefit From Structured Behavior Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572

BIG PICTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 576

Appendix A: Analyzing Data in Psychological Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Appendix B: Quizzes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R-1

Permissions Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P-1

Name Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N-1

Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-1

PSYCHOLOGY IN YOUR LIFE

YOU’RE DRIVING DOWN THE STREET, talking on your cell phone as you negotiate the traffic,

stop signs, and pedestrians. Then the driver in front of you stops suddenly. You frantically drop the

phone and swerve, barely avoiding a collision. Your heart is pounding as you realize what could have

happened.

1 Introducing the World of Psychology

BIG QUESTIONS 1.1 Why Is Psychology Important to You?

1.2  What Do Psychologists Investigate?

1.3  Who Are Psychologists Today?

1.4 How Do Psychologists Conduct Research?

■ 33

4 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

Kelsey raffaele, a 17-year-old high school senior in Michigan, wasn’t so

lucky (Figure 1.1). In January 2010, Kelsey was driving through town after

school and decided to pass a slower vehicle in front of her. When she saw

an oncoming vehicle in the passing lane, she misjudged the distance and

crashed. Kelsey spoke her last words on her cell phone as she talked with her

best friend, Stacey hough: “Oh [no], I’m going to crash.”

If you are like 70 percent of the people in the United States, you talk on

a cell phone every day when you are driving. This habit is so common that

most of us never think twice about it. That’s exactly what Stacey hough

reported. She was driving behind Kelsey at the time of the accident. “[We]

used our phones all the time behind the wheel. We never thought anything

would come of it,” said Stacey. “Until it happen[s], you don’t think it could

happen.”

Statistics contradict people’s intuition that they can drive safely when talk-

ing on the phone. The National highway Traffic Safety Administration estimates

that about 1.4 million car crashes each year, a little less than one-third of all car

crashes, involve drivers who are using cell phones. cell phone use is reported

in about 18 percent of distracted driving fatalities. The common wisdom is that

these accidents happen because the driver has only one hand on the wheel

while holding the phone with the other. Because of this habit, several states

have enacted laws that require the use of hands-free phones while driving. But

even when they have two hands on the steering wheel, can people really drive

safely while talking on the phone?

Unfortunately, we cannot use intuition to answer questions like this one.

Intuition fails here because what seems to be obvious is rarely the whole

story. Behind the “obvious” are mental processes that cause us to think

and act in certain ways. In fact, according to the latest research findings,

a driver’s performance is similar whether he is holding a phone or using a

hands-free device. This finding implies that the absence of one hand on the

steering wheel is not the problem. The distraction of the conversation is the

main reason drivers miss the important visual and audio cues that ordinarily

would help them avoid a crash.

having all the data can help us make informed decisions about what actions

to take. In the case of cell phones and driving, the research suggests that current

legislation is not likely to reduce risk. Instead, we must limit cell phone use while

driving. But how can public policies succeed in getting people not to use cell

phones when driving, if these drivers believe they are not at risk? could manu-

facturers create cell phones and other in-car products that are less distract-

ing when drivers use them? And how might we understand which drivers are

most at risk and provide intervention for them?

When you decided to take a psychology course, you probably did not think

it would deal with issues such as cell phone use. But questions like these are

at the forefront of psychological research. This text introduces you to current

topics and looks at how you can use psychology to think critically and guide

your daily life. Just imagine what this knowledge might have done for Kelsey

raffaele—and for the thousands of other people like her who perish in distracted

driving accidents every year.

Figure 1.1 psychology in Daily Life: The Dangers of Using a Cell phone While Driving Kelsey raffaele took this photo of herself

(photo courtesy of her mother, Bonnie

raffaele). Bonnie raffaele helped get a

new law passed in their state that prevents

novice drivers from using cell phones

while driving. for more information on

the dangers of using a cell phone while

driving, please visit thekdrchallenge.com/

Kelsey_s_Story.html.

1.1 Why Is Psychology Important to You?

Understanding and applying the principles of psychology can affect us in criti- cal ways. For example, psychology can help us understand why we should not talk on our cell phones while driving. It can also help us understand other people. Why are some people fascinated by celebrities, such as Kim Kardashian and Justin Bieber, whereas many others try to ignore media coverage of celeb- rities (Figure 1.2)? Or think about the last time a friend or family member did something that really surprised you. You may have wanted to understand that person’s motives, thoughts, desires, intentions, moods, actions, and so on.

All of us want to know whether other people are friends or enemies, leaders or followers, likely to reject us or fall in love with us. We also want to understand ourselves—why we love the people we do, why we get so angry when someone laughs at us, or why we made that “stupid mistake.” Psychology can help us understand other people and ourselves. In turn, this understanding can help us improve our friendships, work more effectively in groups, be better parents, and have more success in our academic work and at our jobs. In short, psychology can help us improve our lives.

Psychology Explains Our Mental Activity and Behavior We saw in this chapter’s opening story that people believe they can talk on a cell phone and still drive safely. This story is important because it shows that we cannot use our intuition to truly understand people or to predict behavior. By contrast, psychology is the systematic, objective study of our mental activity and our behavior.

Mental activity lets us perceive the world. That is, we use our senses—sight, smell, taste, hearing, and touch—to take in information from outside ourselves. Through mental activity, we interpret that information—each of us in our own unique ways. These processes of the mind, of receiving and interpreting information, are respon- sible for all of our memories, thoughts, and feelings. By contrast, the term behavior refers to all of our actions that result from sensing and interpreting information. It is important to remember that both our mental activity and our behavior are produced by our brains. In recent years, technology such as brain imaging has provided great

psychology The study of mental activity and behavior,

which are based on brain processes.

WhY IS PSYchOlOGY IMPOrTANT TO YOU? ■ 5

LEaRNING GOaLS REaDING aCTIVITIES

a. remember the key terms about psychology. list all of the boldface words and write down their

definitions.

b. Apply critical thinking to your life. Use the three critical thinking questions to come to an

appropriate conclusion about an issue in your life.

c. Apply psychology to your life. Give three examples of how the material and/or skills you

learn in this course can help you improve your life.

Figure 1.2 Understanding people Psychology can help us understand

ourselves. It also provides insight into

why some people find certain celebrities

fascinating. here, fans pose for selfies

with Kim Kardashian (top, left) and Justin Bieber (bottom, middle).

6 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

TRY IT YOURSELF: What Is Psychology?

Which picture(s) show aspects of psychology? See the answer below.

This woman is

experiencing depression.

These people are friends. This couple enjoys the

thrill of roller coaster

rides.

This is a color

blindness test (see

the 5?).

The design of

this door is

confusing—

push or pull?

Answer: All of these pictures reflect psychology because they suggest the presence

of mental processes and behavior that depend on brain activity.

insight into how our brains process information to let us think about and respond to information in the world around us.

So psychology focuses on mental activity, behavior, and brain processes. The areas of investigation range from the simple to the complex. What are some of the topics of interest in psychology? Using the Try It Yourself feature, see if you can figure out the answer.

Are you getting the impression that every aspect of what we think and do relates to psychology? Then you are right. You might be surprised to know that as you sit reading this textbook, you are experiencing psychology. Your eyes move across the page so you can see the words and understand their meaning. You are thinking about what is written, but maybe you are also feeling hungry. Perhaps you are thinking about someone you just met. You want to do well in this class, so you take notes on what you are reading in order to remember it. Psychology is a part of every moment of your life because everything you are thinking and doing relates to psychology.

Psychology Teaches Us to Think Critically Do you believe in extrasensory perception (ESP)? ESP refers to the supposed ability to receive information directly through the mind, not through the physi- cal senses such as vision or hearing. However, there is no compelling scientific support for ESP or mental telepathy. Yet according to a 2005 survey (Musella, 2005), 41 percent of Americans believe in ESP. What’s more, about 37 percent of people believe in mental telepathy—the idea that one person can read another person’s mind. Before taking a psychology course, many students believe things they ’ve heard about the brain, mental activity, and behavior without stopping to think about why they believe what they do. But a main goal of this course is

to teach you to stop and investigate before you believe. In other words, in this course, you will learn to think critically.

STEpS IN CRITICaL THINKING In critical thinking, we systematically evaluate information to reach reasonable conclusions based on the evidence. Three steps are involved in becoming a skilled critical thinker.

The first step in critical thinking is to ask “What am I being asked to believe or accept?” Here we use friendly skepticism: keeping an open mind about a new idea or claim, but being cautious instead of accepting the infor- mation at face value. This combination of openness and caution is easy to achieve when a claim does not fit with our personal views. But we especially need to practice friendly skepticism when we think that we already “know” something.

The second step in critical thinking is to ask “ What evidence is provided to support the claim?” Here, we use logic and reasoning to determine whether there are holes in the evidence or whether the information might be biased. For example, does the person presenting the information have a personal or political agenda?

The last step of critical thinking is to ask “What are the most reasonable conclu- sions?” Here, we consider whether there might be alternative explanations for the claim. We also make our final decisions about whether we believe the claim or not.

The Learning Tip explains how this book will help you develop strong critical thinking skills. Essentially, you will practice using these three steps to evaluate claims you see in the popular media. The media love a good story, and they often jump on findings from psycho- logical research. Unfortunately, as you will see, media reports can be distorted or even totally wrong.

EVaLUaTING pSYCHOLOGY IN THE

NEWS One example of new psychology research that was turned into an overblown news report concerns the so-called Mozart effect. According to the original research, research participants showed significant but temporary gains in perfor ming one type of task after listening to a Mozart sonata for 10 minutes, compared with listen- ing to relaxation instructions or silence (Rauscher & Shaw, 1993).

News outlets quickly reported these results, but they misunderstood or misrep- resented the findings with headlines that suggested that listening to Mozart was a way to increase intelligence (Figure 1.3). Even people surrounded by professional advisors can fall prey to such media reports. In this case, the governor of Georgia, Zell Miller, set aside $105,000 of the state budget to provide classical music to each of the approximately 100,000 children born in the state each year. Though the babies and their parents may have enjoyed the music, there is no evidence that listening improved the infants’ intelligence.

WhY IS PSYchOlOGY IMPOrTANT TO YOU? ■ 7

Throughout this textbook, Being a critical consumer

features will help you develop critical thinking skills. These

features present recent news articles from the popular

press that make claims about psychological research. Each

time you read a Being a critical consumer feature, try

to answer the three key questions about the claim being

made:

1. What am I being asked to believe or accept?

2. What evidence is provided to support the claim?

3. What are the most reasonable conclusions?

LEaRNING TIp: Developing Critical Thinking Skills

Recent research in

psychology reveals that

listening to Mozart increases

intelligence. After reading

about the power of the

“Mozart effect,” the governor

of Georgia, Zell Miller, set

aside a chunk of the state

budget to provide classical

music to every child born in

the state each year.

According to Miller, the

“Mozart effect”

Breaking News: Listening to Mozart Makes People Smarter October 14, 1993

Figure 1.3 Thinking Critically about psychology in the News Media reports seek to grab attention. The

claims can be based on psychological

research, but they can also be hype.

consider what happened when research

revealed small gains in one type of

performance task after participants

listened to a Mozart sonata for 10 minutes.

The media dubbed these gains the

Mozart effect and falsely reported that

listening to Mozart could make people

smarter.

critical thinking Systematically evaluating information

to reach reasonable conclusions best

supported by evidence.

Thinking critically about claims in psychology will help you in your daily life. This ability will also help you study successfully in this and other classes. Indeed, one study found that students who use critical thinking skills complete an intro- ductory psychology course with a more accurate understanding of the subject than do students who complete the same course without using critical thinking skills (Kowalski & Taylor, 2004).

Psychology Helps Us Succeed in School and at Work Apart from a good grade, what do you hope to get out of this class? You’ll find this class valuable whether it ends up being the only psychology course you ever take, you become a psychology major, or you plan to pursue a graduate degree and become a psychologist. Studying psychology can pave the way for success both in your schoolwork and in your professional life.

aCaDEMIC SUCCESS Learning about psychology’s major issues, theories, and controversies will help you succeed in your academic work. For example, in Chapter 7 you will learn how attention and memory work. This material will help you read and remember information better. In Chapter 9, you will learn about the connections between motivation and emotion. This information will help you motivate yourself to succeed.

Furthermore, as you learn about these psychological concepts, you will be developing important abilities: analyzing information by breaking it into pieces, evaluating ideas by drawing conclusions about them, and communicating about psychological concepts. In short, when you follow the simple rules in Using Psy chology in Your Life, you will be well on your way to using psychological prin- ciples to help you achieve success in your schoolwork.

pROFESSIONaL SUCCESS Studying psychology will also prepare you for success in your professional life (Figure 1.4). Teachers and education profes- sionals need to understand how people’s thinking, social abilities, and behaviors develop over time (Chapter 4). Health care workers need to know how to relate to their patients, how patients’ behaviors are linked to health, and what moti- vates or discourages patients from seeking medical care or following treatment plans (Chapter 11). People in business, marketing, advertising, and sales need

8 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

(a)

Figure 1.4 Studying psychology Develops Career Skills Studying psychology helps people develop skills they can use in a wide range of careers. (a) Teachers need to understand how people learn. (b) People in medical professions need to know how to gauge people’s moods and their motivations to recover. (c) To convince people to buy products, salespeople need to understand the relationship between motivation and emotion.

(b) (c)

Knowing about psychology can be useful to you in many ways, even if

you do not pursue a career in the field. The following learning strategies

are all based on psychological research, and they will help you learn more

efficiently and work more productively. Try practicing these techniques

during this course and beyond, and you will see the benefits both in

school and in your career.

1. THE RIGHT GOaLS LEaD TO SUCCESS—Throughout your life, you will set countless short-term and long-term goals for yourself, from

getting that enormous pile of laundry done to succeeding in your job.

In your coursework, it is important to choose goals that are challeng-

ing yet attainable. Then divide each goal into specific, achievable steps,

or subgoals, and reward yourself when you reach a milestone. Even a

small achievement is worth celebrating! In each chapter of this book, the

learning Goals will guide you in successfully reading the material.

2. a LITTLE STRESS MaNaGEMENT GOES a LONG WaY—Stress is a fact of life. A moderate amount of stress can improve your performance

by keeping you alert, challenged, and focused. however, too much stress

has the opposite effect and can diminish your productivity, interfere with

your sleep, and even take a toll on your health. When the pressure is

on in school, seek healthy ways to manage your stress, such as exercis-

ing, writing in a journal, spending time with friends, practicing yoga, or

meditating.

3. CRaMMING IS a CRUMMY WaY TO LEaRN—You have a busy life, and it is always tempting to postpone studying until the night before

an exam. But there is too much to learn to do that. You might be able

to remember enough information to pass the exam the next day, but

research shows that your learning won’t last. To make learning stick, you

need to space out your study sessions over the semester and build in

plenty of time for active reviews.

4. LEaRNING IS aN aCTIVE ENDEaVOR—The more effort you put into studying actively over many days, the more benefit you will receive.

Every time you learn something, you create “memory traces” in your

brain. And by working with the information, you strengthen the memory

traces, so you will be more likely to recall the memory in the future. As

a result, merely rereading a chapter is not as effective as actively work-

ing with the information. Be sure to write down information as you read,

write answers to the reading Activities, and so on.

5. EXpLaINING ENHaNCES UNDERSTaNDING—Memorizing informa- tion—for example, by writing definitions—is likely to result in shallow

learning that is easily forgotten. By contrast, a deeper level of learning

results when we connect information with what we already know. As

you study for this course and answer the reading Activities, be sure to

describe concepts in your own words and apply the concepts to your life.

6. THERE aRE MaNY WaYS TO LEaRN—People process information in two channels: visual and verbal. So another strategy for creating dura-

ble learning is to use both visual and verbal information. Supplement

the notes you take with visuals such as concept maps, graphs, flow-

charts, and other types of diagrams. doing so makes you more likely to

remember the information. And by emphasizing the connections among

important ideas, you are also more likely to see the big picture.

7. SELF-QUIZZING IMpROVES LEaRNING—Testing yourself frequently is a good way to help you remember the material. One way to test your-

self is to take the practice quizzes found in Appendix B at the back of

this book.

USING pSYCHOLOGY

IN YOUR LIFE:

How Can Psychology Help Me Study?

10 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

to know how attitudes are formed or changed and how well people’s attitudes predict their behavior (Chapter 12). Basically, as humans dealing with other humans, we all need to know psychology. Prospective employers in most fields— including business, education, law enforcement, medicine, social services, child care, and retail sales—know how important it is to understand people. Smart employers look for applicants who have knowledge and skills that come from training in psychology.

Some students become so fascinated by psychology that they devote their lives to studying the brain, mental activity, and behavior. And if you are think- ing about a career in psychology or a related field, there is good news. According to the U.S. Department of Labor (U.S. Bureau of Labor Statistics, 2014), oppor- tunities for people with graduate degrees in psychology are expected to grow by about 12 percent by 2022. The outlook is equally positive in many other countries around the world. Developing countries, for example, are increasingly addressing the psychological well-being of their citizens. These efforts are providing hands- on opportunities for people trained in psychology to use their knowledge and skills. As they discover, psychology is an exciting field. Researchers around the globe are reporting new insights into issues that great scholars of the past tried to understand. These insights are helping to explain the very nature of what it means to be human.

■ We experience psychological issues every minute of our lives, but we cannot

understand them based on common sense alone.

■ Psychology is the scientific study of mental activity, behavior, and the brain.

■ Studying psychology helps improve critical thinking skills and study skills. It

also helps develop skills that make people successful in their jobs.

1.1 CHECKpOINT: Why Is Psychology Important to You?

1.2 What Do Psychologists Investigate?

LEaRNING GOaLS REaDING aCTIVITIES

a. remember the key terms about what psychologists

investigate.

list all of the boldface words and write down their

definitions.

b. Apply the nature/nurture debate to your own life. Give examples of how your thoughts and behavior are

influenced by nature and by nurture.

c. Understand the three psychology schools of thought

that investigated the conscious mind and the

unconscious mind.

describe in your own words each school of thought that

investigated the conscious mind and the unconscious mind.

d. Evaluate the four psychology schools of thought that

investigate behavior and mental activity.

Assess why psychology schools of thought shifted to

investigating behavior and mental activity.

Is the mind separate from the brain (dualism)? Or is the mind a product of brain activity?

dualism

WhAT dO PSYchOlOGISTS INvESTIGATE? ■ 11

For as long as people have been able to think, we have been trying to understand ourselves and others. The goal of understanding human thought and behavior actually originated in philosophy. Indeed, some of the most important questions that psychologists now examine intrigued ancient scholars thousands of years ago. However, since scientists began to systematically investigate psychological processes over a century ago, we have made incredible progress in understanding how people think and behave.

Psychology Originated in Philosophical Questions In ancient Greece, early philosophers, such as Aristotle and Plato, debated psychological issues. Was how a person thought and acted inborn—in other words, did thinking and behavior result from a person’s biological nature? Or were thinking and behavior acquired through education, experience, and culture—for example, did they result from how a person was nurtured? Psychologists have carried on this nature/nurture debate for as long as psychology has been a field of study. Psychologists now widely recognize that both nature and nurture influ- ence our psychological development. Throughout this book, you will see many examples of how nature and nurture influence each other so much that they are hard to separate.

Another classic question in psychology is the mind/body problem. Are the mind and the body separate and distinct? Or is the mind simply our own personal expe- rience of the physical brain’s activity? The ancient Greeks and Romans knew that the brain was essential for normal mental functioning. Their understanding came largely from their observations of people who suffered blows to the head, then lost consciousness or experienced changes in certain mental abilities, or both. By contrast, at other points in history, scholars believed that the mind was separate from and in control of the body. This claim was partly based on the strong religious belief that humans have a divine and immortal soul. In this view, the soul is separate from the physical body and departs from the body upon death.

In the 1600s, the French philosopher René Descartes suggested the idea of dualism, that the mind and the body are separate yet intertwined (Figure 1.5). The body, Descartes argued, was nothing more than an organic machine governed by “reflex.” In keeping with the prevailing reli- gious beliefs, he concluded that the rational mind was divine and separate from the physical body. Today, psychologists reject dualism. The current view among psychologists is that the mind emerges from activity— information processing—in the brain.

Psychologists Investigate the Conscious and Unconscious Mind Historically, philosophers used thinking and intuition to answer the big questions about who we are. However, in the mid-1800s in Europe, psychology arose as a scien- tific field of study and then spread throughout the world. During this time, differ- ent ways of thinking about psychology emerged. After a school of thought emerged, it would dominate for a while. When the flaws of that approach became apparent, a new school of thought would emerge. Let’s look at how several schools of thought have laid the foundation for the modern science of psychology (Table 1.1).

Figure 1.5 Descartes and the Mind/Body problem: Dualism According to the philosopher rené

descartes, the mind and the body are

separate yet intertwined. As discussed

throughout this book, psychologists now

reject this idea, called dualism. Instead,

they view the mind as a product of brain

processes.

12 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

SCHOOL OF THOUGHT aND INFLUENTIaL SCIENTISTS

GOaL

Structuralism • Wilhelm Wundt • Edward Titchener

Identify the basic parts, or structures, of the conscious mind

Functionalism • William James • charles darwin

describe how the conscious mind aids adaptation to an environment

psychoanalytic theory • Sigmund freud

Understand how unconscious thoughts cause psychological disorders

Gestalt psychology • Max Wertheimer • Wolfgang Köhler

Study subjective perceptions as a unified whole

Behaviorism • John B. Watson • B. f. Skinner

describe behavior in response to environmental stimuli

Humanistic psychology • Abraham Maslow • carl rogers

Investigate how people become happier and more fulfilled; focus on the basic goodness of people

Cognitive psychology • George Miller • Ulric Neisser

Explore internal mental processes that influence behavior

Table 1.1

EXpERIMENTaL pSYCHOLOGY BEGINS Experimental psychology began in 1879, when Wilhelm Wundt established the first psychology laboratory (Figure 1.6). Wundt based his investigations on a realization: Psychological processes are the products of brain activity, so they must take time to occur. The time it takes to complete a psychological task is called reaction time. Wundt inferred that

Figure 1.6 Wundt’s Experimental psychology Laboratory Wilhelm Wundt (third from left) established the first psychology laboratory

in Germany in 1879. This event marked

the beginning of modern experimental

psychology.

WhAT dO PSYchOlOGISTS INvESTIGATE? ■ 13

more-complex psychological tasks would require more brain activity and so would take longer than simple tasks. To this day, researchers use reaction time to study psychological processes, although their equipment is far more modern.

Wundt was not satisfied with studying mental reaction times. He developed a new method to measure people’s conscious experiences. This method was called intro- spection. In using introspection, research participants had to reflect and report on their thoughts about their personal experiences of objects. For example, partici- pants would experience a series of objects and say which one they found the most pleasant. Wundt’s work investigating conscious experiences was critical to the development of psychology. He trained many of the great early psychologists who went on to establish psychological laboratories throughout Europe, Canada, and the United States.

STRUCTURaLISM: COMpONENTS OF THE CONSCIOUS MIND One of Wundt’s students was Edward Titchener (Figure 1.7). Titchener pioneered a school of thought that became known as structuralism. This school is based on the idea that conscious experience can be broken down into underlying parts. Titchener believed that if psychologists could understand the basic elements of conscious experience, they would have a scientific basis for understanding the mind.

Suppose a research participant was played a musical tone or shown an object, such as an apple. Through introspection, the participant would analyze the subjec- tive experience. In this way, the researcher would understand the component parts of the participant’s experience, such as the quality and intensity of the stimulus (Figure 1.8). Although Wundt ultimately rejected the use of introspection, Titch- ener relied on the method throughout his career.

The general problem with introspection is that it is personal and unique to each person who is having the experience. In other words, each of us brings to introspec- tion a unique way of perceiving things. Researchers cannot determine whether participants in a study are using introspection in a similar way. Over time, psychol- ogists largely abandoned introspection because it was not a reliable method for understanding psychological processes across different people. Even so, Wundt, Titchener, and other structuralists were important because they helped develop a pure science of psychology with its own vocabulary and set of rules.

FUNCTIONaLISM: pURpOSE OF THE CONSCIOUS MIND One critic of structuralism was William James (Figure 1.9). James suggested that structural- ism failed to capture the most important aspects of mental experience. He argued that the mind was much more complex than its elements and could not be broken down. Psychologists who used the structural approach, he said, were like people

“It’s red. It’s bright.”

Figure 1.8 Structuralism and Introspection In structuralism, a person would perform

introspection about an object. for

example, the person might report on the

quality (“red”) and intensity (“bright”) of

an apple. The person’s verbal reports were

thought to reveal the basic parts of the

conscious mind.

Figure 1.9 William James William James, the founder of

functionalism, investigated the

function of the conscious mind.

he wanted to understand how the

operations of the mind help people

adapt to environmental demands.

adaptation structuralism An early school of psychology that

explored the structures of the mind

through introspection.

Figure 1.7 Edward Titchener Edward Titchener founded structuralism.

This school used introspection to

investigate the basic parts of the

conscious mind.

14 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

trying to understand a house by studying each of its bricks individually. More important to James was that the bricks together formed a house and that a house has a particular function. In short, the mind’s elements mattered less than the mind’s usefulness to people. This approach came to be known as functionalism.

According to functionalism, the mind came into existence over the course of human evolution. The mind works as it does to help preserve human life over time. In other words, the mind helps humans adapt to environmental demands. Thanks to the mind, humans survive and pass along their genes to future generations.

EVOLUTIONaRY THEORY: NaTURaL SELECTION aIDS SURVIVaL  One of the major influences on functionalism was the work of the naturalist Charles Darwin. In 1859, Darwin published his revolutionary book On the Origin of Species. This work introduced the world to evolutionary theory. Darwin had studied the variations in species and in individual members of

species. He reasoned that species change over time. Earlier philosophers and natu- ralists had discussed the possibility that species might evolve. But Charles Darwin was the first to present the mechanism of evolution, which he called natural selection (Figure 1.10).

The basic units of natural selection are genes. These genes contain heredi- tary information, which is passed from parents to offspring. But in the inheri- tance of genes, random mutations occur. These mutations produce variations in individuals. Some of these changes—specific physical characteristics, skills, and abilities—make an individual better adapted to its environment. Individuals with such adaptations will be more likely to survive and reproduce than individuals without the adaptations. And because the individuals survive and reproduce, their genes are passed on to offspring. This idea has come to be known as “survival of the fittest.” But survival of the fittest doesn’t happen only once. Presumably, the offspring of the fittest will in turn survive and reproduce. The offspring of their offspring will survive and reproduce. And so on. As the adaptive genes are passed on to more and more offspring of succeeding generations, a species will change.

This kind of change is called evolution. Darwin’s ideas have deeply influenced science, philosophy, and society.

Rather than being a specific area of scientific inquiry, evolutionary theory is a way of thinking that can be used to understand many aspects of mind and behavior (Buss, 1999).

pSYCHOaNaLYTIC THEORY: UNCONSCIOUS CONFLICTS Twentieth-century psychology was profoundly influenced by one of its most famous thinkers, Sigmund Freud (Figure 1.11). Freud was trained in medicine. At the beginning of his career, he worked with people who had nervous system disorders, such as the paralysis of various body parts. He found that many of his patients had few medical reasons for their paraly- sis. Soon he came to believe that psychological factors were causing their conditions. To try to understand the connections between psychology and physical problems, Freud developed psychoanalytic theory.

Freud concluded that much of human behavior is determined by mental processes operating below the level of conscious awareness. He believed that these unconscious mental forces included both troubling childhood experiences blocked from memory and sexual urges that conflicted with acceptable behavior. By creating psychological blockages within the individual, these forces produced psychological discomfort and even mental disorders.

functionalism An early school of thought concerned with

the adaptive purpose, or function, of mind

and behavior.

natural selection In evolutionary theory, the idea that those

who inherit characteristics that help them

adapt to their particular environments

have a selective advantage over those who

do not.

Figure 1.10 Darwin and Natural Selection charles darwin observed that species

change over time. Such change enables

species to adapt and survive. The

mechanism of change—the engine of

evolution—is called natural selection.

These ideas led to the development of

evolutionary theory.

Figure 1.11 Sigmund Freud Sigmund freud founded psychoanalytic

theory. freud used psychoanalysis to treat

unconscious mental forces that conflicted

with acceptable behavior and produced

psychological disorders.

theory

WhAT dO PSYchOlOGISTS INvESTIGATE? ■ 15

Figure 1.13 Max Wertheimer Max Wertheimer was a founder of Gestalt

psychology. According to this school of thought,

people’s experiences cannot be broken down

into parts. Instead, perception is unique for each

person and is affected by context.

Figure 1.12 psychoanalysis in Our Lives Psychoanalysis had a large impact on the

early treatment of psychological disorders.

But today most clinical psychologists use

different techniques to treat psychological

disorders.

TRY IT YOURSELF: Gestalt Theory and the Whole Versus the Parts

What do you see when you look at this figure? do you

see just a group of dots? Or do some of the dots form

an image?

After looking at the picture for a moment, most

people see a dalmatian, a white short-haired dog with

spots, sniffing the ground. According to Gestalt theory,

the mind automatically organizes the picture’s individual

elements: the dots. By organizing the dots, the mind

produces the whole perception of the dog. Once you

perceive the whole of the dog, it is nearly impossible not

to see it.

From his theories, Freud developed the practice of psychoanalysis. In this therapeutic approach, the therapist and the patient work together to bring the contents of the patient’s unconscious into the patient’s conscious awareness (Figure 1.12). Once the patient’s unconscious conflicts are revealed, the therapist helps the patient deal with them constructively. Freud was influential in shap- ing the public view of psychology, but many of his ideas are difficult to test using scientific methods.

Psychologists Explore Behavior and Mental Activity In the early twentieth century, psychological researchers shifted away from studying the conscious and unconscious experiences of the mind. Some research- ers, such as the Gestalt psychologists, believed that mental experience cannot be broken down into common underlying parts. Other researchers, such as the behaviorists, believed that the conscious mind and the unconscious mind were not appropriate topics for psychological investigation. The ideas of Gestalt psychol- ogy, behaviorism, and subsequent schools are the basis for modern psychological research on mental activity.

GESTaLT pSYCHOLOGY: EXpERIENCING THE “WHOLE” Gestalt psychology developed in opposition to structuralism. This new school of thought sought to understand how people perceive information. The most prominent Gestalt psychologists included Max Wertheimer (Figure 1.13) and Wolfgang Köhler.

In 1912, the Gestalt psychologists began to explore how people experi- ence sensory input. For example, why can two people view an object in very different ways? How can one person look at an object more than once and see it differently each time? You can experience such a shift in the Try It Yourself feature. Research into such questions led to the development of

16 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

Gestalt theory. According to this set of ideas, the perception of objects is a personal experience. In other words—in direct contrast with structuralism—what a person experiences is different from all of the constituent elements of an object. The Gestalt perspective has influenced many areas of psychology, including the study of vision and our understanding of human personality.

BEHaVIORISM: STIMULI aND RESpONSES In 1913, the psychologist John B. Watson (Figure 1.14) challenged the focus on conscious and unconscious mental processes as being unscientific. He felt that if psychology was going to be a science, it had to stop trying to study mental events that could not be observed directly. Instead, Watson believed that animals— including humans—learned all behaviors through environmental factors. Specifically, Watson believed that

psychologists needed to study the environmental stimuli, the behavioral triggers, in particular situations. By understanding the stimuli, people could predict the animals’ behavioral responses in those situations. Watson developed the school of behaviorism, which investigates the observable environmental effects on behavior. Watson’s views have been furthered by thousands of psychologists, including B. F. Skinner.

Behaviorism dominated psychological research well into the early 1960s. Behaviorists established many basic principles that are still viewed as critical to understanding behavior (Figure 1.15). At the same time, enough evidence has accumulated to show that thought processes really do influence behav- ior. Few psychologists today describe themselves as strict behaviorists.

HUMaNISTIC pSYCHOLOGY: FOCUS ON pOSITIVES In the 1950s, most schools of thought viewed behavior as resulting from events outside people’s control. Freudians saw unconscious forces as guiding behavior,

whereas behaviorists saw environmental factors as guiding behavior. Rejecting these views, psychologists such as Abraham Maslow and Carl Rogers (Figure 1.16) focused on how people are free to choose activities that make them happy and bring them fulfillment. This more positive perspective toward personal growth became

Figure 1.15 Behaviorism in Our Lives Many people use the principles of

behaviorism to train animals. To

increase a desired behavior, the

trainer provides an environmental

stimulus that is rewarding.

here, a woman gives a treat

reward to a dog that sits up on

command. The same principles

of behaviorism can be used to

teach a child how to behave in a

desirable way.

Figure 1.14 John B. Watson John Watson founded behaviorism,

the scientific study of how observable

environmental factors affect behavior.

B

Rogers Humanistic psychology

How do people change in positive ways?

Focus on people’s basic goodness

Figure 1.16 Carl Rogers carl rogers was a founder of humanistic

psychology. According to this school of thought,

people are motivated to grow in ways that

improve their lives.

Gestalt theory The idea that the whole of personal

experience is different from simply the

sum of its parts.

behaviorism A school of thought that emphasizes the

role of environmental forces in producing

behavior.

humanistic psychology A school of psychology that investigates

how people grow to become happier

and more fulfilled; it focuses on the basic

goodness of people.

known as humanistic psychology. This approach empha- sized the basic goodness of people. It focused on how people should accept themselves, work on personal goals, and try to live up to their full potential as human beings (Figure 1.17).

Building on these earlier ideas, the positive psychology movement was launched by the psychologist Martin Seligman (Seligman & Csikszentmihalyi, 2000). Seligman and others have encouraged the scientific study of how faith, values, creativity, courage, and hope affect us. Positive psychology emphasizes the quality of relationships and taking enjoyment from life’s accomplishments. You will learn in Chapter 13 that there are many benefits to being positive in your outlook.

COGNITIVE pSYCHOLOGY: MENTaL aCTIVITY In the second half of the twentieth century, evidence slowly emerged that learning was not as simple as the behaviorists believed. For example, learning theorists such as Edward Tolman showed that animals could learn just by observation even if they were not triggered to learn by a reward in the environment. Other findings were also difficult for behaviorism to explain and suggested that mental functions were important for understanding behavior.

In 1957, George A. Miller (Figure 1.18) and his colleagues, including Ulric Neisser, launched the cognitive revolution in psychology. Today, cognitive psychology is concerned with investigating mental functions such as intelligence, think- ing, language, attention, learning, memory, problem solving, and decision making (Figure 1.19). While some early cognitive psychologists focused exclusively on mental processes, others recognized that the brain was important to cognition. In the early 1980s, cognitive psychologists joined forces with computer scientists, philosophers, and researchers who studied the brain. The goal of this collabora- tion was to develop an integrated view of mind and brain. During the next decade, cognitive neuroscience emerged. The field of cognitive neuroscience studies the brain mechanisms that underlie thought, learning, and memory.

WhAT dO PSYchOlOGISTS INvESTIGATE? ■ 17

Figure 1.19 Cognitive psychology in Our Lives cognitive psychology reveals how we pay attention, remember, solve problems, and make

decisions. This information can be used to improve our learning and our daily lives. Indeed,

many of the features in this textbook are based on the principles of cognitive psychology,

so using this book will help you learn.

Figure 1.18 George Miller George Miller was a founder of cognitive

psychology. This modern school of

psychology uses experimental methods to

investigate how people think, remember,

pay attention, make decisions, and solve

problems.

cognitive psychology The study of how people think, learn, and

remember.

Figure 1.17 Humanistic psychology in Our Lives humanistic psychology studies how we are

motivated to grow in positive ways, such

as by working hard to achieve goals.

18 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

1.1 CHECKpOINT: What Do Psychologists Investigate?

■ The classic questions in psychology, such as the nature/nurture debate and

the mind/body problem, originated in philosophy.

■ Early psychological schools of thought explored the conscious mind and the

unconscious mind.

■ for example, structuralism examined the content of thought, whereas

functionalism examined the purpose of thought. Psychoanalytic theory focused on

unconscious forces.

■ later schools of thought have explored mental activity and behavior.

■ for example, Gestalt psychology has focused on the whole as different from

its parts. Behaviorism has investigated how environment affects behavior.

humanistic psychology has studied how people can increase positive

aspects of their lives, focusing on how people are basically good. cognitive

psychology has studied mental processes.

1.3 Who Are Psychologists Today?

LEaRNING GOaLS REaDING aCTIVITIES

a. remember the key terms about who psychologists are

today.

list all of the boldface words and write down their

definitions.

b. Analyze how psychologists do research at four different

levels of analysis.

differentiate between the four levels of analysis for the

research question “What motivates a person to overeat at a

holiday meal?”

c. Apply the eight subfields of psychology to your own life. Give four examples of how research from different subfields

could have a positive impact on your life.

d. Understand the five ethical issues in psychological

research.

Summarize in your own words the five ethical guidelines

that psychologists must address in their research.

Do you enjoy listening to music? Why do you like some kinds of music and not others? Do you prefer some types of music when you are in a good mood and other types when you are feeling down? If you listen to music while you study, does it affect how you learn? Let’s look at how psychologists today investigate interesting questions such as these.

Psychologists Work Across Levels of Analysis Through the history of psychology, the various schools of thought helped shape how psychologists viewed mental activity and behavior. Today, the schools are less important. Researchers now typically focus on trying to understand a particular

WhO ArE PSYchOlOGISTS TOdAY? ■ 19

phenomenon by examining it from many different perspectives. Suppose they want to understand how people experience music and are affected by it. The researchers will study many aspects of musical experience. They might examine, for instance, how musical preferences vary among individuals and across cultures, how music affects emotional states and thought processes, and even how the brain perceives sound as music rather than noise. Let’s see how psychologists today might research this one topic in diverse ways across four levels of psychological analysis.

DIFFERENT LEVELS OF pSYCHOLOGICaL aNaLYSIS Table 1.2 outlines the four broadly defined levels of analysis that reflect current approaches to investigating topics in psychology: biological, individual, social, and cultural.

The biological level of analysis deals with how the physical body influences our thoughts and behavior. The last three decades have seen tremendous growth in understanding the biological bases of mental activities. We now know that genes affect thoughts, actions, feelings, and disorders and that certain psychological processes are associated with activity in specific parts of the brain. Psychologists today who work at this level of analysis have shown that musical training changes brain structures associated with learning and memory (Herdener et al., 2010).

Table 1.2

Four Levels of psychological analysis

LEVEL OF aNaLYSIS

FOCUS WHaT IS STUDIED?

Biological

Brain systems Neuroanatomy, animal research, brain imaging

Neurochemistry Neurotransmitters and hormones, animal studies, drug studies

Genetics Gene mechanisms, heritability, twin and adoption studies

Individual

Individual differences Personality, gender, developmental age groups, self-concept

Perception and cognition Thinking, decision making, language, attention, memory, vision

Behavior Observable actions, responses, physical movements

Social

Interpersonal behavior Groups, relationships, persuasion, influence, workplace interactions

Social cognition Attitudes, stereotypes, perceptions

Cultural Thoughts, actions, behaviors in different societies and cultural groups

Norms, beliefs, values, symbols, ethnicity

20 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

Listening to pleasant music increases activation of brain regions associated with positive experiences (Koelsch, Offermanns, & Franzke, 2010). And music appears to be treated by the brain as a special category of auditory information (Figure 1.20). One 35-year-old woman whose brain was damaged lost the ability to recognize even the most familiar tunes, although other aspects of her memory system and language system were intact (Peretz, 1996).

The individual level of analysis focuses on individual differences in personal- ity and mental processes that affect perception and understanding. In the case of music, researchers who work at this level of analysis look for individual differ- ences in music’s effects on mood, memory, and decision making (Levitin, 2006). Have you ever had a bad romantic breakup and spent a lot of time listening to sad songs? Studies have shown that listening to certain types of music changes people’s moods and makes their feelings more intense (Baumgartner, Lutz, Schmidt, & Jäncke, 2006). Indeed, young children listening to sad music tend to interpret a story negatively, and those listening to happy music tend to interpret a story more positively (Ziv & Goshen, 2006). Our expectations also shape how we experience music (Collins, Tillmann, Barrett, Delbé, & Janata, 2014).

Was there ever a time when you were sad and a friend dragged you to a party? In that situation or a similar one, what happened to your mood? The social level of analysis involves investigating how groups affect people’s interactions and people’s influence on each other. In studying the effects of music, researchers look at the types of music people prefer when in groups versus when they are alone. They also investigate whether certain types of music promote negative behaviors. For instance, certain types of rap music have been associated with violence and drug use (Miranda & Claes, 2004). Similarly, people who prefer heavy metal, punk, reggae, and techno music are more likely to use alcohol, drugs, and tobacco than are people who prefer pop or classical music (Mulder et al., 2009). However, listening to music with prosocial lyrics led participants to be more empathic and increased their helping behavior (Greitemeyer, 2009). Such associations do not mean that listening to music always causes these behaviors. Perhaps people who already behaved that way also developed those musical preferences.

The cultural level of analysis explores how people’s thoughts, feelings, and actions are similar or different across cultures. Culture is made up of beliefs, values, rules, norms, and customs that people learn from one another when they share a common language or environment. If you have friends from other cultures, or if you listen to world music, you’re aware that different cultures prefer different types of music (Figure 1.21). Part of the explanation may lie in the music itself. For instance, African music has rhythmic structures different from those in Western music (Agawu, 1995), which may be due to the important role of dancing and drum- ming in these cultures. Further, attitudes about people who are different from us can affect our perceptions of their musical styles. For example, societal attitudes toward rap and hip-hop music in the United States and United Kingdom revealed subtle prejudicial attitudes against blacks and a greater willingness to discrimi- nate against them (Reyna, Brandt, & Viki, 2009).

As these examples show, when the research question calls for it, psychologists today investigate a question across different levels of analysis in an interconnected way. And conducting innovative research at several levels of analysis creates a broader understanding of both mental processes and behavior. Throughout this book, you will see how this multilevel approach has led to breakthroughs in psycho- logical understanding. The Gestalt psychologists were right: The whole is different from the sum of its parts.

Figure 1.20 Your Brain on Music certain regions of the brain are associated

more with organized sounds than with

scrambled sounds. The highlighted region

on the left becomes more active when

you hear spoken language or music. Noise

does not activate that region.

culture The beliefs, values, rules, and customs that

exist within a group of people who share

a common language and environment and

that are transmitted through learning from

one generation to the next.

WhO ArE PSYchOlOGISTS TOdAY? ■ 21

Psychologists Investigate Many Different Topics A psychologist’s career involves predicting behavior or understanding mental activ- ity. Psychologists today achieve this aim by working in many different settings depending on whether their primary focus is on research, teaching, clinical practice with patients, or applying scientific findings to improving the quality of daily living.

Researchers who study the brain, the mind, and behavior may work in schools, businesses, universities, or clinics (Figure 1.22a). Some psychological practitioners apply the findings of psychological research to helping people in need of psychologi- cal treatment, designing safe and pleasant work environments, counseling people on career paths, or helping teachers design better educational experiences. The distinction between psychological research and clinical psychology can be fuzzy. Many researchers are also clinical practitioners, and many clinical psychologists study psychological disorders as well as treat them.

Figure 1.21 Cultural Differences in Music differences across cultures can include musical traditions

and preferences. (a) Traditional African music involves complex rhythms, organic instrumentation, and an

emphasis on drumming. (b) By contrast, modern pop music in Korea, K-pop, involves glossy production, electronic

elements, and the visual dazzle of girl bands or boy bands.

(a) (b)

Figure 1.22 Where psychologists Work and What They Do (a) This pie chart shows the types of settings in which psychologists work, based on data from 2007. (b) This pie chart shows psychology doctoral degrees awarded for the 2007–2008 academic year.

(a) (b)

54.6% Clinical

3.2% General experimental 4.2% Industrial and organizational

4.4% Personality, social, and cultural

6.2% Neuroscience/ biological

7.7% School/ educational

8.7% Counseling

5.3% Cognitive

5.7% Developmental

10% Government

27% Private companies

21% Self-employed

35% Universities and four-year colleges

7% Schools and other educational settings

22 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

SUBFIELD RESEaRCH INTERESTS SaMpLE RESEaRCH QUESTIONS

Biological psychology

Study how biological systems give rise to mental activity.

• how do brain chemicals influence sexual behavior?

• how do brain cells change during learning?

Cognitive psychology/ Neuroscience

Study attention, perception, mem- ory, problem solving, and language, often based on brain processes.

• What makes some problems harder to solve than others?

• how do cell phones distract people when they drive?

Developmental psychology

Study how people change from infancy through old age.

• how do children learn to speak?

• how can older adults maintain mental abilities as they age?

personality psychology Study enduring characteristics that people display over time and across circumstances.

• Why are some people shy?

• how do genes, circumstances, and culture shape personality?

Social psychology

Study how people are affected by others.

• When do people form impressions of others?

• how do people form or dissolve intimate relationships?

Cultural psychology Study how people are influenced by the societal rules that dictate behavior in their cultures.

• how does culture shape the sense of self?

• does culture create differences in perception?

Clinical psychology

Study the factors that cause psy- chological disorders and the best methods to treat them.

• What factors lead people to feel depressed?

• how does the brain change as a result of therapy for depression?

Industrial/organizational psychology

Study issues pertaining to industry and the workplace.

• how can building morale help motivate workers?

• how can equipment be designed so workers can easily perform duties and avoid accidents?

Table 1.3

Research-Related Subfields in psychology

The diverse nature of modern psychology is outlined in Table 1.3, which shows the wide range of interests psychologists have across the eight main subfields in the discipline. Figure 1.22b gives the percentages of psychologists who recently received doctoral degrees in those subfields.

In many of these subfields, psychologists conduct research. In other subfields, psychologists focus more on providing services to individuals and groups. For example, counseling psychology professionals support people who want to improve their daily lives by helping them cope with challenges and crises in personal, professional, and academic domains. Professionals in school psychology work in educational settings. They help students with problems that interfere with learning, design age-appropriate curricula, and conduct aptitude achievement tests.

As you can see, psychology is remarkably diverse in its levels of analysis and its subfields. Psychologists are concerned with nearly every aspect of human life. However, all psychologists follow strict ethical guidelines as they investigate mental processes and behavior.

Psychologists Today Follow Strict Ethical Guidelines When psychologists conduct research, they must fully consider the ethical issues involved. Are they asking the participants to do something unreasonable? Are

WhO ArE PSYchOlOGISTS TOdAY? ■ 23

the participants risking physical or emotional harm from the study? To ensure the participants’ well-being, all colleges, universities, and research institutes have strict guidelines in place regarding research. All researchers must follow those guidelines (Figure 1.23).

The guardians of the ethical guidelines at schools and other insti- tutions where research is conducted are institutional review boards (IRBs). These boards consist of administrators, legal advisers, trained scholars, and members of the community. The members review all proposed research to ensure that it meets scientific standards. For research to be ethical, five main issues must be addressed.

1. Privacy: Researchers must respect participants’ privacy. For exam- ple, it is ethical to observe people without their knowledge in public, such as at an airport. It is not ethical to observe private behaviors without people’s knowledge.

2. Confidentiality: Participants’ information must be kept secret. It can be made available only to the few people who need to know it. This confiden- tiality prevents other people from linking the study’s findings to the actual participants.

3. Informed consent: Informed consent means that people must be told about the research, and they can choose to participate or not. Usually, the participant gives consent in writing before the study begins.

4. Deception: Sometimes, knowing a study’s specific goals could alter the partici- pants’ behavior. That alteration could make the results meaningless. In such a case, the researchers may use deception to mislead participants about the study. If deception is used, once the study is completed the researchers must inform the participants of the study’s goals and explain why deception was necessary.

5. Risks: Researchers cannot ask participants to endure unreasonable pain or discomfort. However, potential gains from research sometimes require asking participants to expose themselves to some risk to obtain important findings. The risk/benefit ratio is an analysis of whether the research is important enough to be worth placing participants at some risk.

In fact, you can experience psychological research yourself if you volunteer to participate in studies at your school. By participating in this research, you can learn more about the field. You will also contribute to the scientific understand- ing of how humans think and behave. And you will be protected by rigorous ethical guidelines.

institutional review boards (IRBs) Groups of people responsible for reviewing

proposed research to ensure that it meets

the accepted standards of science and

provides for the physical and emotional

well-being of research participants.

Figure 1.23 Student participants When you volunteer to participate in

psychological research, you will be

protected by ethical guidelines as you

learn about psychology and contribute to

the field.

■ Psychologists today investigate diverse questions across one or more of four

levels of analysis: biological, individual, social, and cultural.

■ Psychologists now work in many settings, such as at universities and colleges,

for businesses, for the government, and in private practice.

■ Across a wide variety of subfields, psychological researchers investigate

different aspects of mental activity and behavior.

■ Psychologists must adhere to all ethical guidelines when conducting scientific

research.

1.3 CHECKpOINT: Who Are Psychologists Today?

24 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

1.4 How Do Psychologists Conduct Research?

scientific method A systematic procedure of observing and

measuring phenomena (observable things)

to answer questions about what happens, when it happens, what causes it, and why. This process involves a dynamic interaction

between theories, hypotheses, and research

methods.

theory A model of interconnected ideas or

concepts that explains what is observed

and makes predictions about future

events.

hypothesis A specific prediction of what should be

observed if a theory is correct.

descriptive methods A research method that provides a

systematic and objective description of

what is occurring.

LEaRNING GOaLS REaDING aCTIVITIES

a. remember the key terms about the scientific method. list all of the boldface words and write down their definitions.

b. Analyze the five-step cycle of the scientific method. change figure 1.24 to show how you could scientifically

investigate distracted driving when people use their cell phones.

c. Understand the three psychological research methods. describe each method and its pros and cons in your own words.

d. Apply correlations to your life. Give two examples of correlations in your life.

You’ve decided to buy a new a smartphone, but you aren’t sure which one is best. You’ve seen ads for many different brands and models, all with different speci- fications, but can you believe what they say? You might ask your friends what smartphone they like. Or you might go to an expert authority, such as an electron- ics retailer, to compare specifications and features. Maybe you go online to look at product reviews and consumer comments. We answer questions in our daily lives by using these sorts of techniques all the time. But psychologists can’t answer questions based on beliefs, hearsay, rumor, or even expert opinions.

Psychologists Use the Scientific Method Psychology is a science. Because they are scientists, psychologists gain accurate knowledge about behavior and mental processes only by observing the world and measuring various aspects of it. This approach is called empiricism. To be confident about the conclusions drawn from their observations, psychologists conduct empirical research using the scientific method.

There are three key aspects of the scientific method. First, the scientific method requires that psychologists follow several carefully planned, systematic steps. Second, the processes that psychologists use in the scientific method must be objective—that is, free from bias. Third, the procedures must be reproducible. This statement means that if other psychologists repeat the same procedures with simi- lar people, they would expect to obtain the same results. Only when the scientific method is followed can we be confident that our empirical results provide a true understanding of mental activity and behavior.

FIVE STEpS IN THE SCIENTIFIC METHOD The process of the scientific method includes the five steps shown in Figure 1.24. Let’s look at each step in turn.

Psychologists study research questions they find interesting. Psychologists are often people-watchers, and when they see a person behaving in a puzzling way, they want to understand that behavior. The process of understanding follows the scientific method. The scientific method usually begins with a theory (see Figure 1.24, Step 1). Typically, a psychologist develops a theory to explain some interesting or puzzling phenomenon—an observable thing—the psychologist has noticed. A theory is an explanation or model of how the phenomenon works. The theory consists of interconnected ideas or concepts that are used to explain prior research findings and to make predictions about future events.

hOW dO PSYchOlOGISTS cONdUcT rESEArch? ■ 25

When forming their theories, researchers often consider previous studies on the topic. A literature review is an exami- nation of the scientific literature related to the theory. Many resources are available for literature reviews. For example, scientific research databases include PsycINFO, PubMed, and Google Scholar. The results of your searches reveal if and how other scientists have been testing ideas similar to yours. Their approaches may help you refine your theory.

A clearly stated theory is important because it is the basis for the next step of the scientific method: developing a hypothesis (see Figure 1.24, Step 2). A hypothesis is a specific, testable prediction about the theory. Any one theory is usually tested by several separate hypotheses, all testing various aspects of the theory.

Now you move to the third step in the scientific method: testing the hypothesis (see Figure 1.24, Step 3). There are three main types of research methods you can use to test your research question: descriptive, correlational, and experimental (Figure 1.25). Which method you use depends on the goal of your research, as described in the next section.

In Step 4 of the scientific method, you analyze the data to see whether your hypo thesis is supported (see Figure 1.24, Step 4). First, you summarize the raw data using descrip- tive statistics. Then you use inferential statistics to determine whether differences really exist between sets of numbers in descriptive statistics. Both of these forms of analysis are described in Appendix A: Analyzing Data in Psychological Research, at the back of the book.

After the completion of this step, you must determine what issues need additional investigation (see Figure 1.24, Step 5). Remember, no single study gives us a definitive answer about any psychological topic. A study tells us only what happened in a particular set of circumstances. As a result, scientists never say they have proved a theory. However, we generally can feel more confident about scientific findings when the particular study and its outcomes are repeated by the same researcher or others. When the results from two or more studies are the same, or at least support the same conclusion, the findings are more likely to be trustworthy. For psychology studies, the findings add to our understanding of mental activity, behavior, or both.

Descriptive Methods Describe What Is Happening Now that you have learned the five steps of the scientific method, let’s look in more detail at Step 3: testing with a certain research method. Your choice of one of three research methods (see Figure 1.25) depends on the goal of your research. If the goal of your research is describing behavior, then you would use one of the descriptive methods to collect data to test your hypothesis.

You test your hypothesis by selecting the most appropriate research method. You then collect data to evaluate your hypothesis. For example, in an experiment you might have some participants in your study drink alcohol and others drink tonic water.

You submit results to research journals and present them at conferences to share them with the scienti�c community. Then you continue the process by re�ning your theory, making further predictions, and testing hypotheses.

Your hypothesis is that people who consume more alcohol will tend to display poorer motor control in driving than will people who consume less alcohol.

2 State a hypothesis.

3 Test with a research method.

4 Analyze the data.

5 Report results and embark on further inquiry.

You analyze the data using appropriate statistical techniques and draw conclusions. If the data do not support your hypothesis, you either discard the theory or revise it (and make plans to test the revision). See, at the back of the book, Appendix A: Analyzing Data in Psychological Research.

Focus on a theory.1

Your theory is that drinking alcohol impairs driving ability. A literature review of existing studies informs your theory.

Figure 1.24 Cycle of the Scientific Method

26 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

A descriptive method provides a snapshot of what is occurring at a specific point in time. As a result, this technique is especially valuable in the early stages of research. During the early stages, researchers are trying to see whether a particular phenomenon exists. Let’s look at three descriptive methods you might use: observational studies, self-reports, and case studies.

OBSERVaTIONaL STUDIES Observational studies are a specific type of descriptive method. They involve systematically assessing and coding observ- able behavior (Figure 1.26). By coding, we mean determining which previously defined category the behavior fits into. For example, researchers might note the types of gestures people make when meeting at an airport. They might group the behaviors of nonhuman animals that have been injected with drugs that affect brain function.

Observational studies can be used either in the laboratory or in natural envi- ronments. Some researchers observe behavior at regular time intervals. These intervals may be as short as seconds or minutes, or they may be as long as years, entire lifetimes, and even across generations. By using intervals, the researchers can keep track of what research participants do at specific points in time.

Figure 1.26 Observational Studies (left) The evolutionary psychologist lawrence Sugiyama, here hunting with a

bow and arrow, has conducted fieldwork in

Ecuadorian Amazonia among the Shiwiar,

Achuar, Shuar, and Zaparo peoples.

(right) The primatologist Jane Goodall observes a family of chimpanzees.

Observational studies are a descriptive research method. They involve observing and classifying behavior, either with intervention by the observer or without intervention by the observer.

Advantages Especially valuable in the early stages of research, when trying to determine whether a phenomenon exists. Can take place in a laboratory or a real-world setting.

Disadvantages Errors in observation can occur because of an observer’s expectations (observer bias). Observer’s presence can change the behavior being witnessed (reactivity).

With intervention Without intervention

Types of research methods

Case studies

Experimental methods

Describe what is occurring.

Test the relationship between factors.

Investigate what causes an outcome.

Descriptive methods Correlational methods

Observational studies

Self-reports

Figure 1.25 Types of Research Methods

hOW dO PSYchOlOGISTS cONdUcT rESEArch? ■ 27

It is often hard to observe a situation without seeing what we expect or want to see. In conducting observational studies, researchers must guard against observer bias. Bias refers to errors in observation that occur because of the observer’s expec- tations. Observer bias can especially be a problem if cultural norms favor behav- ing in certain ways. For instance, in many societies women are freer to express sadness than men are. As a result, in coding men’s and women’s facial expressions, an observer may be more likely to rate female expressions as indicating sadness. The observer may tend to rate men’s expressions of sadness as annoyance or some other emotion.

Another problem with observational studies is that they can produce artificial behavior. Such behavior will not reflect how people naturally behave. For exam- ple, the presence of an observer might alter the behavior being observed. Suppose people want to make a positive impression on an observer. They may act differ- ently when they believe they are being observed. Such an alteration is called reac- tivity. A classic study on a form of reactivity, the Hawthorne effect, is described in the Scientific Thinking feature.

SELF-REpORTS For some kinds of research, observational studies are not appropriate. A different descriptive method consists of obtaining self-reports from research participants (Figure 1.27).

Questionnaires or surveys can be used to gather data from a large number of people in a short time. These research tools are easy to administer as well as cost- efficient. With groups that cannot be studied through questionnaires or surveys

SCIENTIFIC THINKING: The Hawthorne Effect

21

Hypothesis: Being observed can lead participants to change their behavior.

Research Method:

Result: The workers’ productivity increased when they were being observed, regardless of how the independent variable was changed.

Conclusion: Being observed can lead participants to change their behavior, because people often act in particular ways to make positive impressions.

Question: Which research method described in Figure 1.25 was used in this study? How did you arrive at this answer?

The researchers then measured the dependent variable: the speed at which workers did their jobs.

During studies of the effects of workplace conditions at the Hawthorne Plant, a Western Electric manufacturing plant, the researchers manipulated several independent variables. These variables included the levels of lighting, pay incentives, and break schedules.

28 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

(for example, young children), interviews can be used. Interviews are also help- ful in getting more details about the respondents’ opinions, experiences, and atti- tudes. That is, the answers during the interview may lead the researchers to ask questions they had not planned.

A problem common to all self-report methods is that people’s answers can involve personal biases called self-report bias. Sometimes people may not reveal personal information that casts them in a negative light. If you are in your twen- ties, imagine having an interviewer around your parents’ age ask you to describe intimate aspects of your sex life. If you are an older student, imagine a twenty- something interviewer asking the same question. How truthful would you be? Researchers have to consider whether their questions might lead a person to respond in a way that is most socially acceptable. Any distortion of the truth— whether it is meant to please or displease—will present a biased view. Psycholo- gists therefore design self-reports so that people feel comfortable providing information. For example, the researchers make clear to the participant that all responses will be confidential.

Figure 1.27 Self-Reports (left) researchers can ask participants to complete surveys or questionnaires.

(right) Alternatively, the researchers can interview the participants.

Surveys and questionnaires Interviews

Self-reports are a descriptive research method that involves asking questions of research participants. The participants then respond in any way they feel is appropriate or select from among a �xed number of options.

Advantages Self-reports such as surveys and questionnaires can be used to gather data from a large number of people. They are easy to administer, cost-ef�cient, and a relatively fast way to collect data. Interviewing people face-to-face gives the researcher the opportunity to explore new lines of questioning.

Disadvantages People can introduce biases into their answers (self-report bias). They may not recall information accurately.

Figure 1.28 Case Studies (left) In december 2012, a 20-year-old gunman went on a shooting spree at

Sandy hook Elementary School, in

Newtown, connecticut. The gunman killed

twenty-six teachers and young students

before killing himself. (right) The gunman’s name was Adam lanza. This photo shows

lanza as a seemingly happy and healthy

young boy. The Sandy hook shooting

provides a case study of how an individual

can become disturbed enough to commit

a terrible act.

Case studies are a descriptive research method that involves intensive examination of one person or organization or a few individuals or organizations.

Advantages Can provide a lot of data.

Disadvantages Can be very subjective. If a researcher has a preexisting theory (for example, people who are socially awkward are dangerous), this theory can bias what is observed, investigated, and recorded. The results cannot be generalized from a single case study to the population.

hOW dO PSYchOlOGISTS cONdUcT rESEArch? ■ 29

CaSE STUDIES Case studies involve intensive examination of a few unique people or organizations (Figure 1.28). For example, case studies of people with brain injuries have provided a wealth of evidence about which parts of the brain are involved in various psychological processes. In one case, a man who was acci- dentally stabbed through the middle part of the brain with a fencing foil lost the ability to store new memories (Squire & Moore, 1979). This study was important for indicating which parts of the brain are involved in memory.

Case studies of people with psychological disorders are used frequently in psychology. The major problem with these clinical case studies is that it is difficult to know whether the researcher’s theory about the cause of the psychological disorder is correct. The researcher has no control over the person’s life and is forced to make assumptions about the effects of various life events.

Correlational Methods Test Associations Suppose we want to study the relationship between drinking alcohol and driving performance. When we want to examine the relationship between two factors, we often start with correlational methods. These methods enable us to examine how one factor is related to another factor. How so? In correlational methods, the inves- tigators do not alter the factors being studied or claim that one factor causes the other (Figure 1.29). They simply measure the two factors and then determine the degree of association between the two variables.

As an example, say you form the hypothesis “There is a relationship between drinking alcohol and showing impaired motor skills.” You could use a correlational method to test this hypothesis. To do so, you might measure people’s self-reported alcohol use and also their self-reported car accident history. These data would enable you to examine how drinking alcohol and driving performance are related. The data do not, however, show causation—they do not establish that drinking alco- hol actually caused the performance. Why not? A few potential problems prevent researchers from drawing causal conclusions from correlational studies.

CORRELaTION IS NOT CaUSaLITY One problem with correlational studies is in knowing the direction of the relationship between variables. That is, can we determine what causes what? This sort of ambiguity is known as the directionality problem.

correlational methods A research method that examines how

variables are naturally related in the real

world. The researcher makes no attempt

to alter the variables or assign causation

between them.

Figure 1.29 Correlational Methods correlational methods help us

understand whether two factors are

associated. A correlation may exist

between how overweight parents are

and how overweight their children are. A

correlational study cannot demonstrate

the cause of this relationship, which may

include biological tendencies to gain

weight, lack of exercise, and high-fat diets.

Correlational research methods examine how variables are related, without intervention by the observer.

Advantages Rely on naturally occurring relationships. May take place in a real-world setting.

Disadvantages Cannot demonstrate causal relationships (that one thing happened because of the other). Cannot show the direction of the cause/effect relationship between variables (directionality problem). An unidenti�ed variable may be involved (third variable problem).

30 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

For example, suppose you survey a large group of people about their sleeping habits and their levels of stress. Those who report sleeping badly also report having a higher level of stress. Does lack of sleep increase stress levels, or does increased stress lead to shorter and worse sleep? The cause/effect relationship in this example could go in either direction. As shown in the Learning Tip, both lack of sleep and more stress could be causes. But both of them also could be effects. In short, because of the directionality problem, correlational methods cannot tell us what causes a certain outcome.

Another drawback of all correlational studies is the third variable problem. Say your theory is that drinking alcohol causes dangerous driving. What if some other variable causes both of those factors— drinking before driving and dangerous driving? For example, people

who are risk takers may be more likely to drink before driving. Risk takers might also tend to take dangerous chances when driving. Thus the real cause of both drink- ing before driving and dangerous driving might be the third variable, risk taking. Many media reports of correlational studies make it sound as though one variable causes another (Figure 1.30). Failure to consider the directionality and third vari- able problems may lead people to make inaccurate conclusions about relationships. The Learning Tip also explains why these problems prevent us from understanding what causes an outcome in a study using correlational methods.

These examples may make it seem that we should simply disregard the results of correlational studies. On the contrary, correlational studies still provide important information about the natural relationships between variables, enabling researchers to make valuable predictions. For example, correlational research has identified a strong relationship between depression and suicide. For this reason, clinical psychologists often assess symptoms of depression to determine suicide risk. In addition, researchers who conduct correlational stud- ies use statistical procedures to rule out potential third variables and direction- ality problems. Once they have shown that a relationship between two variables holds even when potential third variables are taken into account, researchers can be more confident that the relationship is meaningful. In any case, to truly

The directionality problem and the third variable problem are the two main reasons that correlational methods prevent

us from being able to state that changes in one variable actually cause changes in another. failure to consider these

problems may lead to inaccurate conclusions. here is a way to visualize these problems in correlational methods.

The Directionality problem lack of sleep (A) is correlated with greater stress (B).

• does less sleep cause more stress? (A S B)

or

• does more stress cause less sleep? (B S A)

The Third Variable problem drinking before driving (A) is correlated with driving dangerously (B).

• risk taking (c) causes some people to drink before driving. (c S A)

and

• risk taking (c) causes some people to drive dangerously. (c S B)

LEaRNING TIp: Problems Determining Causality in Correlational Methods

Figure 1.30 Correlations in the News When the media present results from

correlational studies, the reports often

suggest that one factor causes the other.

In such cases, we need to think critically

and remember that just because two

events are associated with each other, we

cannot say whether one causes the other.

hOW dO PSYchOlOGISTS cONdUcT rESEArch? ■ 31

understand psychological findings, it is important to understand the difference between correlation and causation, as shown in the Being a Critical Consumer feature.

Experimental Methods Test Causation So we now know that if a psychologist is using a correlational method, the research will uncover whether a relationship exists between factors. The researcher will not control the situation and so cannot determine whether one factor causes the other. Therefore, if the goal of the research is to determine causation, the psy chol- ogist must use a different type of research method. To determine whether one factor causes the other, experimental methods must be used to test the hypothesis (Figure 1.31).

Kim finished reading chapter 1 of her

psychology text and put the book down.

As a first-semester student, she was a bit

nervous about taking introductory psychol-

ogy because she hadn’t studied psychology

in high school and wasn’t really sure what it

was about. however, her advisor felt that the

course might be helpful for Kim as a market-

ing major. her friends told her that the class

and the professor were really good.

Kim had not realized how varied the

field of psychology is. She especially liked

reading about how psychologists conduct

research. As she turned on her computer,

she thought, I wonder how much of the information I read about every day involves psychological research.

On her startup page, she saw a list of

news headlines. One, from the news service reuters, caught

her attention: “Spanking Kids can cause long Term harm.”

What did that mean? Can spanking cause harm to kids over a long term? Was that statement based on psychological research? The headline was making a causal claim, and Kim wanted to know how the writer could make that claim.

flipping through the chapter she had just read, she found

the statement that only experimental methods can estab-

lish causation. In addition, she read, random assignment to

groups is necessary in an experiment to avoid confounds

and ensure that one factor caused a particular outcome.

If there was a research study, how was it done? Was one set of parents told to spank their children and one set of parents not allowed to spank theirs? Was that an ethical way to conduct a study? Kim also reread the review of ethi- cal guidelines in the chapter. research, it said, should try to

avoid exposing people to unreasonable pain or discomfort.

Would making parents spank their children be ethical? Kim was now very curious about this study. her professor,

dr. Parretti, had told Kim’s class that people should be critical

consumers of the research they read about

in the popular press. Sometimes head-

lines are meant to grab attention but do

not accurately or completely describe the

research that was done. Could this be one of those cases where the research said one thing but the press said another?

determined to get to the bottom of

the question, Kim thought, It’s likely that correlational methods were used to study this topic, probably with self-reports. Researchers could have measured whether spanking occurred in the home and then measured psychological outcomes, such as aggressive behavior and mental health problems. But would this study have warranted the news headlines she had read? With a quick search, she found other

headlines about the study. from U.S. News and World Report: “Spanking Produces Troubled Kids, Study contends.” from

Huffington Post: “children Who Get Physical Punishment Tend Toward Aggression.” from Globe and Mail: “Study links Spanking to later Mental disorders.” Even the headlines

seemed to focus on slightly different aspects of the study!

When Kim found the original study, she saw that the

headlines didn’t completely match what was written by the

journalists or the actual scientists. The published study had

collected 20 years of data on the topic, but it proposed only

a correlation between spanking and harm to children, not a

causal relationship.

QUESTION Kim recognizes that the research results are from correla-

tional studies. Why is this type of study a problem in terms

of judging causality? Can you think of directionality prob-

lems or third variables that might affect the relationship

between spanking and aggression or between spanking

and mental health problems?

BEING a CRITICaL CONSUMER: Does Spanking Cause Long-Term Harm?

experimental methods A research method that tests causal

hypotheses by manipulating independent

variables and measuring the effects on

dependent variables.

32 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

VaRIaBLES aND OpERaTIONaL DEFINITIONS To begin understanding experimental methods, let’s return to the research example concerning alcohol consumption and motor skills. In this case, the hypothesis might be “Consuming more alcohol will cause poorer driving skills.”

To perform an experiment that will test a hypothesis, the researcher manipulates one variable. This variable is called the independent variable. In an example experiment, on drinking alcohol and driving skills, the independent vari- able would be alcohol consumption. The experimenter controls how much alcohol is consumed. After manipulating the independent variable, you measure the effect of that factor on a second factor. The second factor is called the dependent variable. In your experiment, the dependent variable is driv- ing skills. Instead of letting your participants drive, you might measure their skills safely as they use a driving simulator or play

a driving game on a computer (Figure 1.32). The Learning Tip will help you remem- ber the difference between independent and dependent variables.

To ensure that the research is objective and systematic, you have to define the variables more specifically. In other words, you must create operational defini- tions of the variables. To operationally define the independent variable of alco- hol consumption, you can bring the amount of alcohol in each person’s blood to a predetermined level. That level is described by blood alcohol content (BAC). In this experiment, let’s say you manipulate BAC to range from 0.0 (no alcohol) to 0.01–0.05 (relaxed feeling; sense of well-being; impaired thought, judgment, and coordina- tion) to 0.06–0.10 (loss of inhibitions; extraversion; impaired reflexes, depth percep- tion, peripheral vision, and reasoning). Note that the legal limit for driving is 0.08.

Just as you need to operationally define the independent variable, you need to operationally define the dependent variable. One option for the dependent vari- able might be to measure the amount of time it takes participants playing the driving computer game to stop the car when an obstacle appears in the road. In

Figure 1.31 Experimental Methods Experimental research methods

provide information about the causes

of particular mental activities or

behaviors.

independent variable

Experimental research methods examine how one variable that is manipulated by researchers affects another variable.

Advantages Provide control over independent variables, so can demonstrate that one thing causes another. Avoid the directionality problem.

Disadvantages Varying something other than the independent variable (a confound) can affect the dependent variable and lead to inaccurate conclusions. Often take place in an arti�cial setting.

Researcher manipulates…

Researcher randomly assigns subjects to...

Researcher measures...

Researcher analyzes results.

Conclusion

control group

or

experimental group

dependent variable

Are the data in the control group different from the data in the experimental group?

The explanation either supports or does not support the hypothesis. Are there confounds, which would lead to alternative explanations?

1 2 3 4 5

independent variable In an experiment, the variable that the

experimenter manipulates to examine its

impact on the dependent variable.

dependent variable In an experiment, the variable that is

affected by the manipulation of the

independent variable.

Figure 1.32 participants in an Experiment With Simulated Driving An experiment investigating how alcohol

consumption affects driving skills can be

performed safely by having participants

use a driving simulator or play a driving

game. Information about the participants’

driving skills would be recorded

electronically.

hOW dO PSYchOlOGISTS cONdUcT rESEArch? ■ 33

this case, the operational definition of driving skills is in milliseconds of stopping time. Another operational definition of driving skills would be how many times the person playing the driving game crashes the virtual car. Often, a single depen- dent variable can have many operational definitions. Clear operational definitions enable other researchers to know how you measured your variables. Knowing your methods, other researchers can use identical methods in gathering data that will build on your data, supporting or differing from your results.

GROUpS Your experiment tests the hypothesis that the dependent vari- able (driving skills, as measured by either the number of virtual crashes or how long it takes the driver to stop the car) is affected by the independent variable (the amount of alcohol consumed, as shown by BAC). But how do you know if the change in the dependent variable is really caused by your manipulation of the independent variable?

To clarify the relationship between your variables, you assign some participants in the study to a control group. In this case, participants assigned to the control group drink something nonalcoholic, such as tonic water, instead of alcohol. To make sure that both groups expect to be drinking alcohol, you might disguise the tonic water by using lemon or even some alcohol rubbed along the rim of the glass. However, the participants in the experimental group experience the manipulation you are interested in. In this case, they consume enough alcohol to reach a certain BAC level. Because you disguise the tonic water, all the study participants think they are drinking alcohol. You then compare the effects of drinking tonic water in the control group with the effects of drinking alcohol in the experimental group (or more than one experimental group, if you include several levels of BAC in the study).

The benefit of using an experimental method is that the researcher can study the causal relationship between the two variables. Suppose the independent vari- able (BAC in our example) consistently influences the dependent variable (driv- ing skills). The independent variable is then assumed to cause the change in the dependent variable. The experiment makes it possible to rule out alternative explanations, such as third variables. In addition, because the experimenter deter- mines when the independent variable (here, the BAC level) is administered, the experimenter can be sure that this variable comes first in time. In this way, the experimenter also solves the directionality problem.

CONTROL IS NECESSaRY TO DETERMINE CaUSaLITY A properly perfor- med experiment depends on rigorous control. Here, control means the steps taken by the researcher to minimize the possibility that anything other than the indepen- dent variable will affect the experiment’s outcome. When conducting an experi- ment, a researcher needs to ensure that the only thing that varies is the independent variable. That way, the researcher knows that the independent variable— nothing else—has affected the dependent variable. Anything that affects a dependent

control group In an experiment, a comparison group of

participants that receives no intervention

or receives an intervention that is

unrelated to the independent variable

being investigated.

experimental group In an experiment, one or more treatment

groups of participants that receive the

intervention of the independent variable

being investigated.

LEaRNING TIp: Dependent and Independent Variables

WHEN YOU SEE pLEaSE THINK MEaNING

Independent variable In control of the experimenter

The experimenter manipulates what the participant does, sees, experiences, is exposed to, and so on.

dependent variable depends on what the participant does

The experimenter measures only what the participant does.

34 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

variable and that may unintentionally vary between the study’s different experi- mental conditions is known as a confound.

Consider a confound in your hypothetical study of alcohol consumption and driving skills. Suppose the computer game used to assess driving when partici- pants are sober has an automatic transmission. Now suppose the game used with intoxicated participants has a manual transmission (stick shift). If you’re not familiar with both types of transmissions, you might think they’re equal. However, driving a car with a manual transmission takes more skill than driving one with an automatic transmission. As a result, a change in driving performance might actu- ally be caused by the type of car driven in the computer game. In this example, the

drivers’ skills might be confounded with the type of transmis- sion. The presence of a confound would make it impossible to determine the true effect of BAC on driving performance.

The more confounds and thus alternative explanations that can be eliminated, the more confident a researcher can be that the change in the independent variable is causing the change (or effect) in the dependent variable. Control represents the foundation of the experimental approach, because it allows the researcher to rule out alternative explanations for the observed data. As consumers of research, we all need to think about confounds that could be causing particular results that are reported in the news.

RaNDOM aSSIGNMENT REMOVES CONFOUNDS One possible confound in a study is preexisting differences between groups that are assigned to different conditions. Consider your study of drinking and driving. What happens to the results if the people assigned to have many drinks just happen to be heavy drinkers? Some heavy drinkers develop such a tolerance to alcohol that they show few outward signs of intoxication even when their blood alcohol levels are high enough to knock out a typical person (Chesher & Greeley, 1992). By contrast, some participants might become intoxicated on very small amounts of alcohol. Either group might distort the results. The

distorted results would indicate that the effects of alcohol on driving are lesser or greater than they would be in the general population.

Of course, individual differences are bound to exist among participants. For example, any of your groups might include some people with low toler- ance for alcohol and some people with high tolerance, some people with excellent coordination and some people with poor coordination. How do you keep these differences from being a problem? You use random assignment (Figure 1.33a). This method gives each potential research participant an equal chance of being assigned to any level of the independent variable (BAC level, for example). Differences between participants will tend to average out when partici- pants are assigned randomly to either the control group or one or more of the exper- imental groups. Random assignment balances out known and unknown factors.

SaMpLING Now that you know about random assignment, what types of participants would you choose for your hypothetical study? Selecting partici- pants is as important as choosing a research method. Psychologists typically want to know that their findings generalize. In other words, the results should apply to people beyond the individuals in the study. When studying the effects of drinking

random assignment Placing research participants into the

conditions of an experiment in such a way

that each participant has an equal chance

of being assigned to any level of the

independent variable.

Figure 1.33 Random assignment and Random Sampling for the results of an experiment to be

considered useful, researchers must use

random assignment and random sampling.

(a)

(b)

(c)

Control Experimental

Population: This is the group you want to know about (e.g., college students).

Random assignment: Participants are assigned at random to the control group or the experimental group. Each person has an equal chance of being assigned to either group.

Random sample: Participants are selected at random from the population (e.g., selecting students from every school in your country). Each person in the population has an equal chance of being selected.

(c)

hOW dO PSYchOlOGISTS cONdUcT rESEArch? ■ 35

alcohol on driving skills, you want to know more than how the specific participants behaved. Ultimately, you want to discover general laws about human behavior. Such laws will enable you, other psychologists, and people in general to predict how drinking alcohol affects driving performance.

The general group you want to know about is your population. For instance, you might want your results to generalize to college students, to students who belong to sororities and fraternities, to women, to men over the age of 45, and so on. To learn about the population, you study a subset, or a small number, from it. That subset, the people you actually study, is the sample. Sampling is the process you use to select people from the population to be in the study.

One way to represent the whole population is to take a random sample (Figure 1.33b−c). This method gives each member of the population an equal chance of being chosen to participate. Most of the time, however, researchers will use a sample consisting of people who are conveniently available for the study. Even if you wanted your results to generalize to all students in your coun- try or in the world, you would probably use a sample from your own college or university. Even though a sample from your own college might not look like all students in the country, it seems reasonable to expect that the effect of alcohol on human motor skills would be about the same, no matter where you sampled them from. It is important for researchers to recognize that their results might not generalize to other samples that are quite different, such as people from other cultures (Henrich, Heine, & Norenzayan, 2010).

In reading this chapter, you have learned what psychologists have investigated in the past, what they research today, and how they use the scientific method to understand thought and behavior. It’s time to learn about psychology in your life.

■ Psychologists use empiricism to investigate psychological topics by following

the five steps of the scientific method.

■ descriptive methods allow description of what is occurring.

■ correlational methods investigate the relationship between factors.

■ Only experimental methods make it possible to determine a cause and effect

relationship between variables.

1.4 CHECKpOINT: How Do Psychologists Conduct Research?

random sample A sample that fairly represents the

population because each member of the

population had an equal chance of being

included.

36 ■ CHapTER 1 INTrOdUcING ThE WOrld Of PSYchOlOGY

a. remember the key terms about psychology.

b. Apply critical thinking to your life.

c. Apply psychology to your life.

a. remember the key terms about what psychologists investigate.

b. Apply the nature/nurture debate to your own life.

c. Understand the three psychology schools of thought that investigated the conscious mind and the unconscious mind.

d. Evaluate the four psychology schools of thought that investigate behavior and mental activity.

1.1 Why Is Psychology

Important to You?

1.2 What Do

Psychologists

Investigate?

B IG

P IC

T U

R E

a. remember the key terms about who psychologists are today.

b. Analyze how psychologists do research at four different levels of analysis.

c. Apply the eight subfields of psychology to your own life.

d. Understand the five ethical issues in psychological research.

1.3 Who Are

Psychologists Today?

a. remember the key terms about the scientific method.

b. Analyze the five-step cycle of the scientific method.

c. Understand the three psychological research methods.

d. Apply correlations to your life.

1.4 How Do Psychologists

Conduct Research?

BIG QUESTION LEARNING GOALS

BIG PIcTUrE ■ 37

KEY TERMS CHECKPOINT

psychology critical thinking

■ Psychologists today investigate diverse questions across one or more of four levels of analysis: biological, individual, social, and cultural.

■ Psychologists now work in many settings, such as at universities and colleges, for businesses, for the government, and in private practice.

■ Across a wide variety of subfields, psychological researchers investigate different aspects of mental activity and behavior.

■ Psychologists must adhere to all ethical guidelines when conducting scientific research.

culture institutional review boards

(IrBs)

■ The classic questions in psychology, such as the nature/nurture debate and the mind/body problem, originated in philosophy.

■ Early psychological schools of thought explored the conscious mind and the unconscious mind.

■ for example, structuralism examined the content of thought, whereas functionalism examined the purpose of thought. Psychonalytic theory focused on unconscious forces.

■ later schools of thought have explored mental activity and behavior.

■ for example, Gestalt psychology has focused on the whole as different from its parts. Behaviorism has investigated how environment affects behavior. humanistic psychology has studied how people can increase positive aspects of their lives, focusing on how people are basically good. cognitive psychology has studied mental processes.

structuralism functionalism natural selection Gestalt theory behaviorism humanistic psychology cognitive psychology

scientific method theory hypothesis descriptive methods correlational methods experimental methods independent variable dependent variable control group experimental group random assignment random sample

■ Psychologists use empiricism to investigate psychological topics by following the five steps of the scientific method.

■ descriptive methods allow description of what is occurring.

■ correlational methods investigate the relationship between factors.

■ Only experimental methods make it possible to determine a cause and effect relationship between variables.

For a self-quiz on this chapter, go to the back of the book and find Appendix B: Quizzes.

■ We experience psychological issues every minute of our lives, but we cannot understand them based on common sense alone.

■ Psychology is the scientific study of mental activity, behavior, and the brain.

■ Studying psychology helps improve critical thinking skills and study skills. It also helps develop skills that make people successful in their jobs.

In 2012, Jack OsbOurne (Figure 2.1), the 26-year-old son of Ozzy and Sharon Osbourne, cele-

brated the arrival of his daughter Pearl. Just two weeks later, he noticed a disturbing problem with his

vision. He told People magazine (July 9, 2012) about an experience he had at a gas station: “I was talk-

ing to the attendant, and all of a sudden a black dot appeared in my vision. . . . I was like, ‘That’s weird.’

The next day I woke up and the dot had turned into a cigar shape.” Jack’s vision kept getting worse,

until he could barely see out of his right eye. After a series of tests, doctors determined that Jack was

in the early stages of multiple sclerosis.

2 The Role of Biology in Psychology

BIG QUESTIONS 2.1               How Do Our Nervous Systems Affect Thinking

and Behavior?

2.2         How Do the Parts of Our Brains Function?

2.3        How Do Our Brains Communicate With Our Bodies?

2.4      How Do Nature and Nurture Affect Our Brains?

■ 3939

40 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Multiple sclerosis (MS) is a disorder of the nervous system that is typi-

cally diagnosed in people between ages 20 and 40. MS affects the brain and

the spinal cord, so that movements become jerky and people lose the ability

to coordinate their actions. Gradually, the ability to move, see, and think all

become severely impaired. MS affects about 2.5 million people throughout the

world. It is incurable, but in some forms of the disease the symptoms are now

manageable.

The symptoms of MS make clear that our nervous system is critical for think-

ing normally and behaving normally. The nervous system consists partly of

nerve cells, also known as neurons. MS limits the ability of neurons to send

signals to each other and to receive each other’s signals. To picture how a

neuron operates, imagine the plastic around a wire, such as the cord from a

lamp or an appliance. The plastic insulates the wire, allowing electrical current

to run to the lamp so it can turn on. Without that insulating layer, electricity will

never reach the lamp. One part of the neuron, like the lamp cord, is covered by

a fatty layer that enables the neuron to transmit signals to other neurons and

other parts of the body. In MS, the fatty layer deteriorates, and normal commu-

nication between neurons is short-circuited.

To learn about psychology, you need to understand how neural commu-

nication enables us to think and behave. you also need to see how both

nature and nurture affect these processes. We cannot understand thought

and behavior without understanding our underlying biological processes.

2.1 How Do Our Nervous Systems Affect Thinking and Behavior?

Figure 2.1 around the Globe, 2.5 Million people have Multiple sclerosis Jack Osbourne is one of millions of people

with multiple sclerosis. This disease

damages nerve cells in the brain.

The nervous system is a network of billions of cells in the brain and the body. This system is responsible for all aspects of what we feel, think, and do. The nervous system has three basic functions: (1) receive sensory input from the world through vision, hearing, touch, taste, and smell; (2) process the information in the brain by paying attention to it, perceiving it, and remembering it; and (3) respond to the infor- mation by acting on it. To experience these functions, see Try It Yourself.

nervous system A network of billions of cells in the brain

and the body, responsible for all aspects of

what we feel, think, and do.

LearnInG GOaLs readInG actIvItIes

a. Remember the key terms about the divisions of the

nervous system and neurons.

list all of the boldface words and write down their

definitions.

b. Apply the three functions of the nervous system to your

own life.

Describe the three functions of your nervous system during

an experience you had today.

c. Analyze the three steps in neural communication. Organize the three steps of neural communication into an

illustrated short story for young children.

d. Apply neurotransmitters to your life. Describe three experiences you have had that likely each

reflect the function of a specific neurotransmitter.

HOW DO OUR NERvOUS SySTEMS AffEcT THINkING AND BEHAvIOR? ■ 41

trY It YOurseLF: Experiencing the Functions of  Your Nervous System

central nervous system The part of the nervous system that

consists of the brain and the spinal cord.

peripheral nervous system The part of the nervous system that

enables nerves to connect the central

nervous system with the muscles, organs,

and glands.

Sympathetic nervous system

Para- sympathetic

nervous system

Spinal cord

Brain

Nervous system

Peripheral nervous system

Central nervous system

Autonomic nervous system

Somatic nervous system

Figure 2.2 the nervous system The main divisions of the nervous system are the central nervous system and the peripheral

nervous system. Together with their subdivisions, these systems (1) receive sensory input,

(2) process it further, and (3) respond to it.

These three functions are a result of processing in two divisions of the nervous system. The central nervous system consists of the brain and the spinal cord, which both contain massive numbers of nerve cells. The peripheral nervous system consists of the nerve cells in the soft organs in the rest of the body (Figure 2.2). These two units are separate, but they interact constantly. For example, when you touch a sharp tack, the peripheral nervous system registers that sensory signal and transmits the information to the central nervous system. The central nervous system organizes and evaluates that information, then directs the peripheral nervous system to perform specific behaviors, such as moving your hand away from the tack. These two systems work together every moment of our lives, enabling us to think and act.

your nervous system is responsible for how you experi-

ence things. To understand the three functions of your

nervous system, describe the following: (1) What sensory

input are you currently receiving? (2) How are you

processing that information? In other words, what are

you thinking about the sensory information you’re receiv-

ing? (3) In what ways are you responding to the input?

This exercise will help you understand how your nervous

system is the core of all psychological processes in your

life—and in everyone’s lives.

42 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Neurons Are the Basic Units of Our Nervous Systems Both divisions of the nervous system are made up of smaller units. These units are the nerve cells, or neurons (Figure 2.3). Individual neurons receive, integrate, and transmit information in the nervous system. Each neuron communicates with tens of thousands of other neurons. But the neurons do not communicate randomly or by chance. Instead, they communicate selectively with other neurons. Through this selective communication, neurons form networks. The networks of billions of neurons sending and receiving signals make possible all the complex aspects of human thought and behavior. Through maturation and experience, the networks develop and strengthen. In other words, permanent alliances form among groups of neurons. Those alliances enable the neurons to process information strongly and efficiently.

We are able to think and act because neurons are able to communicate with each other. And neural communication is possible because of the neuron’s structure, in addition to the neuron’s electrical and chemical properties.

structure OF neurOns Let’s examine the four parts of a neuron that enable it to communicate with other neurons. These parts are the dendrites, the cell body, the axons, and the terminal buttons (Figure 2.4).

The dendrites are short, branchlike extensions. They detect signals from neigh- boring neurons. In the cell body, the information received from thousands of other neurons is collected and integrated ( joined together). Once the incoming informa- tion has been integrated in the cell body, electrical impulses are transmitted along the axon. Axons vary tremendously in length. In fact, the longest axons stretch all the way from the spinal cord to each of the big toes. In everyday language, we commonly refer to neurons as nerves, as in the phrase “pinched nerve.” In this context, a nerve is a bundle of axons that carry information between the brain and other specific locations in the body. At the end of the axon are knoblike structures called terminal buttons.

The site where communication occurs between neurons is called the synapse. In the synapse, the neurons do not actually touch each other. Instead, they commu- nicate by sending chemicals into a tiny gap between the terminal buttons of the sending neuron and the dendrites of the receiving neurons. The chemicals leave one neuron, cross the synapse, and pass signals along to the dendrites of other neurons.

Figure 2.3 human nerve cell This is a nerve cell, also known as a neuron.

Neurons are the basic units of the human

nervous system.

neurons The basic units of the nervous system;

cells that receive, integrate, and transmit

information in the nervous system.

Neurons operate through electrical

impulses, communicate with other

neurons through chemical signals, and

form neural networks.

Figure 2.4 neuron structure Messages are received by the dendrites, processed in the cell body, transmitted along the axon,

and sent to other neurons via chemical substances released from the terminal buttons to the

dendrites of the receiving neuron. The details of these processes are shown in figures 2.5 and 2.6.

Dendrites Cell body

Axon

Dendrites Cell body

Axon

Direction of electrical impulse

Terminal buttons SynapsesMyelin sheath

(covering axon)

eLectrIcaL prOpertIes OF neurOns Parts of the neuron are covered with a membrane, a thin covering. This barrier separates the inside of the neuron from the outside environment. The membrane is semipermeable. In other words, some substances move through the membrane. These substances are electrically charged chemicals called ions. Ions, such as sodium and potassium, may move from outside the neuron to the inside or from inside the neuron to the outside. The movement of these ions across the membrane enables neurons to communicate.

The membrane contributes to neural communication by regulating the neuron’s electrical activity. It is important to know that the inside and the outside of a neuron have different electrical charges. Think of the positive and negative ends of a battery. The neuron begins in a resting state. During this state, the elec- trical charge inside the neuron is slightly more negative than the electrical charge outside. This difference in electrical charge occurs because of the balance of vari- ous ions inside and outside the neuron.

Now imagine the neuron receives stimulation from nearby neurons. This stim- ulation causes positively charged sodium ions to move through the membrane and into the neuron. The inside of the neuron becomes more positive as sodium enters. If the neuron is stimulated enough, it fires an action potential down the axon to the terminal buttons, where chemicals are released into the synapse.

During an action potential, sodium ions continue to enter the neuron and potassium ions leave the neuron. Within milliseconds, sodium ions stop entering and potassium ions stop leaving. In addition, sodium is pumped out of the neuron while potassium is pumped back in. This sodium potassium pump helps return the neuron to the resting state.

In this way, one neuron is able to send a message to another neuron. Let’s exam- ine the action potential and the process of neural communication in more detail.

Action Potentials Allow Neurons to Communicate With Each Other Neurons communicate with other neurons in three phases (Figure 2.5). During the transmission phase (Step 1), neurons pass signals to receiving neurons. During the reception phase (Step 2), neurons receive signals from neighboring neurons. During integration (Step 3), neurons assess the incoming signals. Then this neural communication process can be repeated, with signals transmitted to yet more neurons. Now let’s look at each of these steps in turn.

actIOn pOtentIaLs In the first step, a neuron is stimulated by signals from other neurons. The stimulated neuron may transmit this information to other neurons (see Figure 2.5, Step 1). What determines whether the neuron will transmit the information it has received? When a neuron is stimulated, posi- tively charged sodium ions enter the neuron. The inside of the neuron becomes more positive as sodium enters. If the electrical charge changes enough, the action potential begins. Traveling along the axon like a wave, the action poten- tial moves away from the cell body. It moves down the axon and toward the terminal buttons.

The action potential travels quickly along the axon. This fast movement is made possible by the fatty layer that insulates the axon. The fatty casing is called the myelin sheath (see Figure 2.4). Because the myelin sheath makes neural communi- cation so quick, you are able to move your hand away from a sharp tack fast enough to keep from getting hurt. However, recall from the chapter opener that Jack

Dendrites Cell body

Axon

Dendrites Cell body

Axon

Direction of electrical impulse

Terminal buttons SynapsesMyelin sheath

(covering axon)

dendrites Branchlike extensions of the neuron with

receptors that detect information from

other neurons.

cell body Part of the neuron where information from

thousands of other neurons is collected

and integrated.

axon A long, narrow outgrowth of a neuron that

enables the neuron to transmit information

to other neurons.

synapse The site where communication occurs

between neurons through neurotransmitters.

action potential The neural impulse that travels along

the axon and then causes the release of

neurotransmitters into the synapse.

HOW DO OUR NERvOUS SySTEMS AffEcT THINkING AND BEHAvIOR? ■ 43

44 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Osbourne’s vision was affected because multiple sclerosis destroys the myelin sheath. Axons that have no insulation cannot effectively continue the action potential. In short, when neurons lose the myelin sheath, they lose the ability to communicate. Various symptoms, such as vision problems, result when neurons can’t communicate.

To communicate, a neuron fires an action potential. A neuron cannot fire just a little bit: It either fires or it does not. How often a neuron fires an action poten- tial can change, though, depending on how much stimulation the neuron receives. To understand this idea, suppose you are playing a video game in which you fire missiles by pressing a button. Every time you press the button, a missile is launched at the same speed as the previous one. It makes no difference how hard you press the button. However, if you press faster, missiles will fire more rapidly one after another. Now suppose the missile launcher is a neuron in the visual system. The neuron receives information that a light is bright. The neuron might respond to that stimulation by firing more often than when it receives information that the light is dim. But whether the light is bright or dim, however many times the neuron fires, the strength of the action potential is the same every time.

Figure 2.5 three steps of neural communication This graphic shows the three steps of neural communication: (1) transmission, (2) reception, and

(3) integration.

2

3

1

Reception: The action potential causes chemicals called neurotransmitters to be released from the terminal buttons at the end of the axon. The neurotransmitters cross the synapse and �t into receptors in the dendrites of the postsynaptic neuron (B).

Integration: Each neurotransmitter has either excitatory or inhibitory effects on the postsynaptic neuron (B). These effects are summed together in the cell body. If there is enough activation, it will lead to another action potential. At that point, the process begins again with Step 1 in a new neuron.

Presynaptic neuron (A)

Postsynaptic neuron (B)

Transmission: Neural communication begins when there is enough stimulation in the presynaptic neuron (A) to create an action potential. The action potential travels quickly down the myelinated axon to the terminal buttons.

Synapse

HOW DO OUR NERvOUS SySTEMS AffEcT THINkING AND BEHAvIOR? ■ 45

Synapse

Action potential

Axon

Neurotransmitters

Receptors for neurotransmitters

Presynaptic neuron (A)

Postsynaptic neuron (B)

neurOtransMItters In the sYnapse As we have seen, neurons do not touch one another. Instead, they communicate chemically at the synapse. So in the second step, reception, action potentials cause a neuron to release chemicals (see Figure 2.5, Step 2). These chemicals travel across the gap at the synapse and enter the receiving neuron’s dendrites. The neuron that sends the signal is called the presynaptic neuron, and the one that receives the signal is called the postsynaptic neuron.

How do these chemical signals work (Figure 2.6)? When an action potential has arrived at the end of the axon, the terminal buttons release neurotransmitters. These chemicals carry information from the presyn- aptic neuron. After spreading across the synapse, the neurotransmitters attach ( bind) to receptors on the postsynaptic neuron. Receptors are specialized molecules that specifically respond to certain types of neurotransmitters. In much the same way as a lock opens only with the correct key, each receptor can be influenced by only one type of neurotransmitter.

Once neurotransmitters are released into the synapse, they stimulate specific receptors by attach- ing to them. This stimulation continues as long as the neurotransmitters are in the synapse. There are two major ways that neurotransmitters are removed from the synapse. The first occurs when the neurotransmitter is reabsorbed by the presynaptic neuron in a process called reuptake. In the second, enzymes destroy the neurotransmitter while it is in the synapse. Enzymes are special chemicals that break down other substances. Different enzymes break down different neurotrans- mitters, in a process called enzyme degradation.

neurotransmitters chemical substances that carry signals

from one neuron to another.

It will be easy to understand how neurons communicate with

each other if you remember the following.

LearnInG tIp: Communication From Presynaptic Neuron to Postsynaptic Neuron

When YOu see

pLease thInk

MeanInG

Presynaptic Before the synapse

Something that occurs in the neuron before the synapse (the gap between neurons)

Postsynaptic After the synapse

Something that occurs in the neuron after the synapse (the gap between neurons)

Figure 2.6 neurotransmitters Move across the synapse The action potential in the presynaptic

neuron results in the release of

neurotransmitters from terminal buttons.

These neurotransmitters cross the synapse

and attach (bind) to specific receptors on

the dendrites of the postsynaptic neuron.

46 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

eXcItatOrY and InhIbItOrY sIGnaLs In the third step, integration, the postsynaptic neuron processes incoming signals (see Figure 2.5, Step 3). The attaching, or binding, of neurotransmitters with their receptors on the postsynap- tic neuron can produce signals of two types: excitatory or inhibitory. As the name indicates, excitatory signals excite the neuron—they increase the likelihood that it will fire. Inhibitory signals inhibit the neuron—they decrease the likelihood that it will fire. Any individual signal received by the neuron has little influence on whether the neuron fires. Instead, thousands of excitatory and inhibitory signals are added together within the cell body of the neuron. If the total amount of excitatory input goes past a certain threshold, the postsynaptic neuron fires an action potential. After firing, the neuron returns to its slightly negative resting state. The process repeats hundreds of times per second.

Neurotransmitters Influence Our Mental Activity and Behavior Much of our knowledge about neurotransmitters has come from research on how drugs and other substances affect emotion, thought, and behavior. Drugs that enhance the actions of neurotransmitters are known as agonists. Drugs that inhibit the actions of neurotransmitters are known as antagonists. Addictive drugs, such as heroin and cocaine, have their effects because they are chemically similar to naturally occurring neurotransmitters. The receptors cannot sense the difference between the ingested drug and the real neurotransmitter released from a presynaptic neuron. Remember, a neurotransmitter fits a receptor the way a key fits a lock. However, the receptor-lock cannot tell a real neurotransmitter-key from a forgery. The receptor can be affected by either a neurotransmitter or a drug that resembles the neurotransmitter.

To assess how neurotransmitters affect behavior, researchers often inject agonists or antagonists into animals’ brains. For instance, scientists may want to test the hypothesis that a certain neurotransmitter in a specific brain region leads to increased eating. Injecting an agonist into that brain region should increase an animal’s eating. Injecting an antagonist should decrease its eating. Such studies help in the develop- ment of drug treatments for many psychological and medical disorders.

There are many kinds of neurotransmitters. Some neurotransmitters are partic- ularly important in understanding how we think, feel, and behave (table 2.1).

acetYLchOLIne Maybe you have seen ads for Botox or known someone who received Botox injections to remove wrinkles. Botox treatments depend on the action of acetylcholine, the neurotransmitter responsible for motor control. After moving across the synapses, acetylcholine binds with receptors on muscle cells. This chemical binding makes the muscles contract.

Where does Botox come in? Botulism, a form of food poisoning, inhibits the release of acetylcholine. The resulting paralysis of muscles leads to difficulty in chewing, difficulty in breathing, and often death. In small, much less toxic doses, the botulism bacteria (popularly known as Botox) paralyze muscles that produce wrinkles in certain areas. The affected areas include the forehead (Figure 2.7). Because the effects of Botox wear off over time, a new dose of botu- lism toxin needs to be injected every 2 to 4 months. But Botox also paralyzes the facial muscles we use to express emotions, as in smiling and frowning. If too much Botox is injected, the result can be an expressionless face.

In addition to regulating motor control, acetylcholine is also involved in some complex mental processes. For example, acetylcholine influences attention,

Figure 2.7 acetylcholine and botox The neurotransmitter acetylcholine is

responsible for motor control between

nerves and muscles. Botox inhibits the

release of acetylcholine, paralyzing

muscles. Here, a woman gets a Botox

injection to remove wrinkles in her

forehead.

HOW DO OUR NERvOUS SySTEMS AffEcT THINkING AND BEHAvIOR? ■ 47

memory, learning, and sleeping. Because acetylcholine plays a role in attention and memory, drugs that are acetylcholine antagonists can cause temporary amnesia. In a similar way, diminished acetylcholine functioning is associated with Alzheimer’s disease, a condition characterized primarily by severe memory deficits (Koen & Yonelinas, 2014). Drugs that are acetylcholine agonists may enhance memory and decrease symptoms of Alzheimer’s. So far, though, drug treatments for the disease have had only limited success (Cummings, Morstorf, & Zhong, 2014).

epInephrIne You’ve certainly experienced an adrenaline rush. This effect is the sudden burst of energy that seems to take over your whole body. The adrena- line rush results from a release of the neurotransmitter epinephrine, formerly called adrenaline. Epinephrine binds to receptors throughout the body. The resulting rush is part of a system called the fight-or-flight response. This system prepares the body for dealing with threats from the environment (Figure 2.8).

The neurotransmitter related to epinephrine, norepinephrine, is involved in states of arousal and alertness. Norepinephrine is especially important for noticing what is going on around you.

serOtOnIn The neurotransmitter serotonin is involved in a wide range of psychological activities. It is especially important for emotional states, impulse control, and dreaming. A lack of serotonin is thought to contribute to sad and anxious moods, food cravings, and aggressive behavior. Some drugs, such as Prozac, that are used to treat a wide array of mental and behavioral disorders—including depression, obsessive-compulsive disorders, eating disorders, and obesity—leave more serotonin in the synapse to bind with the postsynaptic neurons.

dOpaMIne Dopamine has many important brain functions. Its most impor- tant functions are motivation and reward. Consider that people eat when they ’re hungry, drink when they ’re thirsty, and have sex when they ’re aroused.

Figure 2.8 epinephrine and adrenaline rush certain activities, such as bungee jumping,

release the neurotransmitter epinephrine.

you feel the effect of epinephrine as a

sudden burst of energy, sometimes called

an adrenaline rush.

neurOtransMItter FunctIOns

acetylcholine Motor control over muscles Attention, memory, learning, and sleeping

epinephrine Energy

norepinephrine Arousal and alertness

serotonin Emotional states and impulse control Dreaming

dopamine Reward and motivation Motor control over voluntary movement

Gaba (gamma-aminobutyric acid)

Inhibition of action potentials Anxiety reduction Intoxication (through alcohol)

Glutamate Enhancement of action potentials learning and memory

endorphins Pain reduction Reward

TABLe 2.1

common neurotransmitters and their Major Functions

48 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

What physiological system motivates these activities? Behaviors such as these activate dopamine receptors, and the increased dopamine produces a desire to perform the behavior.

By contrast, a lack of dopamine may be involved in problems with movement. Severe loss of dopamine is connected to Parkinson’s disease. First identified by the physician James Parkinson in 1917, Parkinson’s is a degenerative and fatal neurological disorder. It affects about 1 in every 200 older adults and occurs in all known cultures. Most people with Parkinson’s do not experience symptoms until after age 50, but the disease can occur earlier in life. For example, the actor Michael J. Fox was diagnosed with Parkinson’s at age 30.

With Parkinson’s disease, the dopamine-producing neurons in the midbrain (see Figure 2.12) slowly die off. The resulting lack of dopamine causes distur- bances in motor function: rigid muscles, tremors, and difficulty initiating volun- tary action. You can see these symptoms in the shuffling walk of a person with the disease. In the later stages of the disorder, people experience severe cogni- tive and mood disturbances. Injections of one of the chief chemical building blocks of dopamine, l-DOPA, help the surviving neurons produce more dopa- mine. When l-DOPA is used to treat Parkinson’s disease, patients often have a remarkable, though temporary, recovery.

Gaba and GLutaMate The main inhibitory neurotransmitter is GABA ( gamma-aminobutyric acid). It is more widely distributed throughout the brain than most other neurotransmitters. Without the inhibitory effect of GABA, the excitation of neurons might get out of control and spread through the brain chaotically. In fact, epileptic seizures may be caused by low levels of GABA (Chung et al., 2015).

Drugs that are GABA agonists (e.g., Valium) are widely used to treat anxi- ety disorders. The increased inhibitory effect provided by these drugs helps calm anxious people. Alcohol has similar effects on GABA receptors. As a result, people typically experience alcohol as relaxing. GABA reception may also be the primary mechanism that causes alcohol to interfere with motor coordination.

In contrast, glutamate is the main excitatory neurotransmitter. It is involved in fast-acting neural transmission throughout the brain. Glutamate receptors aid learning and memory by strengthening synaptic connections.

endOrphIns You’ve no doubt heard about, or perhaps experienced, “runner’s high.” This psychological state results from a release of endorphins. Endorphins are a class of neurotransmitters involved in reward, such as runner’s high, as well as in natural pain reduction. Pain is useful because it signals that we are hurt or in danger. That signal should then prompt us to try to escape or withdraw. If you didn’t experience pain when you touched a hot stove, you wouldn’t know that you should pull your hand away to avoid being injured.

Pain can interfere with adaptive functioning, however. If pain prevents us from eating, competing, or mating, then people will fail to pass along their genes. Endorphins’ painkilling, or analgesic, effects help us perform these behaviors even when we are in pain. In humans, drugs that bind with endor- phin receptors (e.g., morphine) reduce the subjective experience of pain. Apparently, morphine does not block the nerves that transmit pain signals. Instead, it alters the way pain is experienced. In other words, people still feel pain, but they report a sense of detachment that lets them not care about the pain.

has It happened

tO YOu?

Neurotransmitters and Delayed Pain

Have you ever been hurt in an

accident or had a deep cut? If

so, you may have noticed that

you didn’t immediately feel any

pain. you were initially spared the

pain because the event triggered

the release of endorphins. This

release is a survival mechanism

that enables us to function for a

short time.

After a while, your endorphin

levels declined. you probably

began to feel the pain. you even

may have taken painkilling

medicine to replace the reduced

endorphins so you could

continue to function.

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 49

2.2 How Do the Parts of Our Brains Function?

As we saw at the beginning of this chapter, the nervous system has two main divisions:  the peripheral nervous system and the central nervous system (see Figure 2.2). The central nervous system consists of the brain and the spinal cord. Our basic biological processes, such as our heartbeat, breathing, and reflexes, all depend on the spinal cord. But everything we are and do depends on the brain. To truly under- stand how we see, hear, remember, interact with others, and sometimes experience psychological disorders, we need to understand the main structures of the brain.

Understanding of Our Brains Has Developed Over Time In the first animals, nervous systems were little more than a few specialized cells with the capacity for electrical activity. Today, an adult human brain weighs about 3 pounds (1.4 kilograms) and is quite complex. We can think of the brain as a collec- tion of interacting neural circuits that have accumulated and developed throughout human evolution. In adapting to the environments where humans have lived, the

LearnInG GOaLs readInG actIvItIes

a. Remember the key terms about brain regions and

processes.

list all of the boldface words and write down their

definitions.

b. Apply the three main brain divisions to your own life. Provide one example from your life of how each brain

region processes specific information.

c. Remember the five forebrain subcortical regions.

Recall these regions by using the first letter of each

region to create an acronym. This new word will serve as a

memory tool.

d. Understand the four lobes of the cerebral cortex. Summarize what information is processed in each region,

using your own words.

2.1 checkpOInt: How Do Our Nervous Systems Affect Thinking and Behavior?

■ The central nervous system processes information in the brain and the spinal

cord. The peripheral nervous system processes information in the soft organs.

■ The nervous system has three primary tasks: It receives information, it

integrates that information, and it passes signals to other neurons to allow

thought and action.

■ Neurons are the basic units of the nervous system.

■ changes in a neuron’s electrical charge elicit an action potential. The action

potential causes the release of neurotransmitters that are received by other

neurons.

■ Neurons communicate with each other through neurotransmitters. Each

particular neurotransmitter has specific effects on thought and behavior.

50 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

brain has evolved. As a result of evolution, specialized mechanisms in the brain regu- late our breathing, food intake, sexual behavior, and body fluids. Likewise, sensory systems in the brain aid our navigation and help us recognize friends and foes.

earLY studIes OF the braIn By the beginning of the nineteenth century, early psychologists agreed that mental processes were a result of brain function. What’s more, anatomists understood the brain’s basic structure reasonably well. But debates raged over how the brain produced mental activity. Did different parts of the brain do different things? Or were all areas of the brain equally important in mental activities such as problem solving and memory?

In the early nineteenth century, the neuroscientist Franz Gall and his assistant, the physician Johann Spurzheim, proposed their theory of phrenology. Gall and Spurzheim based their theory on the idea that different areas of the brain perform different functions (Figure 2.9a). Phrenology was the practice of assessing personal- ity traits and mental abilities by measuring bumps on the human skull. Phrenology was popular until as late as the 1930s. At that time, an enterprising company manu- factured 33 psychographs—devices used to analyze personality based on the locations and sizes of skull bumps (Figure 2.9b). Because these machines were featured at state fairs and amusement parks, it is unlikely that many people, if any, took the personal- ity readings seriously. But phrenology was influential. People paid attention to this theory because it was based on the seemingly scientific principle that brain functions had specific locations in the brain. Although bumps on the skull did not turn out to be related to personality, the idea of localization of brain function was an important insight. At the time, the technology was not available to test the theory scientifically.

The first strong evidence that brain regions perform specialized functions came from the work of the physician and anatomist Paul Broca (Finger, 1994). In 1861, Broca performed an autopsy on a patient. The patient had been able to understand language, but had lost the ability to say anything other than one word. When Broca examined the patient’s brain, he found a large section of damaged tissue in the front left side (Figure 2.10a). Broca concluded that this particular region in the left hemisphere of the brain was important for speech. Broca’s theory has survived the test of time. This left frontal region, now confirmed to be crucial for producing speech, became known as broca’s area (Figure 2.10b).

broca’s area A small portion of the left frontal region of

the brain; this area is crucial for producing

speech.

Figure 2.9 phrenology and the psychograph (a) In phrenological maps, each region of the skull is associated with a different

feature of personality to reflect processes

occurring in the brain under the skull.

(b) Psychographs were sold to the public and were claimed to “do the work of a

psychoanalyst” by showing “your talents,

abilities, strong and weak traits, without

prejudice or flattery.”

(a) (b)

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 51

cOnteMpOrarY braIn research For most of hu man history, theorists and researchers did not have methods for studying mental activity as it occurred in the working brain. Over the last century, scientists have developed various meth- ods to study the brain in action.

The first method developed was a way to record the elec- trical activity of neurons firing in the brain. A researcher fits electrodes onto the participant’s scalp. The electrodes act like small microphones, but they pick up the brain’s elec- trical activity instead of sounds. The device that records this activity is called an electroencephalograph (EEG; Figure 2.11a). This measurement is useful because different behavioral states produce different and predictable EEG patterns. An EEG can reveal, for example, when someone is falling asleep. It has also shown that the brain is very active even when the body is at rest, especially during dreams.

The brain’s electrical activity is associated with changes in the flow of blood carrying oxygen and nutri- ents to the active brain regions. These changes can be measured with several different brain imaging methods.

The main brain imaging method used today in psycho- logical research is functional magnetic resonance imaging (fMRI; Figure 2.11b). This technique measures changes in the blood’s oxygen level. These changes enable the research- ers to indirectly assess the brain’s blood flow. Using this method, they are then able to map the working brain. For example, the participant performs a mental task (thinks

Figure 2.10 broca’s area (a) Paul Broca studied a patient’s brain and identified the lesioned area in the left frontal lobe as crucial for producing speech. (b) This illustration shows the location of Broca’s area.

Figure 2.11 Measures of brain activity There are several ways to measure how the brain responds to tasks or

events. These methods give us insight into how thinking and action

depend on our biological processes. (a) An electroencephalograph (EEG) measures the brain’s electrical activity. (b) functional magnetic resonance imaging (fMRI) maps mental activity during a mental task

by assessing the blood’s oxygen level in the brain. (c) Transcranial magnetic stimulation (TMS) momentarily disrupts brain activity in a

specific brain region.

Broca’s area

52 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Hindbrain (survival functions, movement)

Spinal cord (brain–body communication)

Midbrain (movement)

Forebrain (motivation, emotion, complex thought)

about something), such as deciding whether a face looks happy or sad. During the task, the researchers scan the participant’s brain. Next, the participant does a task that differs from the first in only one way. The researchers then compare brain images to examine differences in activity associated with the task.

How do researchers determine whether a brain region is important for a task? Ideally, they want to compare performances when that area is working effectively and when it is not. The method used for this purpose is transcranial magnetic stimu- lation (TMS; Figure 2.11c). This technique uses a very fast and powerful magnetic field to momentarily disrupt activity in a specific brain region. For example, plac- ing the TMS coil over areas of the brain involved in language will disrupt a person’s ability to speak. This technique has its limitations. In particular, it can be used only for short durations to examine brain areas close to the scalp. When used along with imaging, however, it is a powerful method for examining which brain regions are necessary for specific psychological functions.

Contemporary brain research using these methods has greatly advanced our understanding of the brain. Just how important is measuring brain activity? For researchers who want to understand the inner workings of the brain, imaging is equivalent to the telescope for astronomers. In the following sections, we’ll learn how brain research reveals the three main divisions of the brain: the hindbrain, the midbrain, and the forebrain. Each of these divisions is associated with particular mental processes and particular behaviors (Figure 2.12; also see the Learning Tip).

The Hindbrain and Midbrain House Basic Programs for Our Survival The lower part of the brain contains structures that are essential for survival. These structures control breathing, heartbeat, swallowing, and moving. These areas of the brain are connected to the rest of the body through the spinal cord. The cord is a rope of nerves running inside the spine, from just above the pelvis to the base of the skull (see Figure 2.12).

Figure 2.12 three Main brain divisions Shown here are the hindbrain, the

midbrain, and the forebrain, plus the

spinal cord.

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 53

The spinal cord’s most important job is communication between the brain and the rest of the body. The spinal cord carries sensory information up to the brain and carries motor signals from the brain to the body parts to initiate action. For example, the spinal cord coordinates reflexes—such as the way your leg moves when a doctor taps your knee or how your arm moves when you jerk your hand away from a flame.

The spinal cord is composed of two distinct tissue types. One type is gray matter, which is dominated by the cell bodies of neurons. These neurons do not have myelin on their axons. They communicate only with nearby neurons. The other type is white matter, which consists mostly of axons and the myelin sheaths that surround them. These myelinated axons help neurons transmit messages over long distances, both in the spine and in the brain. Indeed, the brain consists of both white matter and gray matter. Let’s learn about the parts of the brain.

hIndbraIn At the base of the skull, the spinal cord thickens and becomes more complex. Here, the cord changes into the hindbrain, which has three structures ( Figure 2.13). The first structure of the hindbrain is the medulla. The medulla controls the most basic functions of survival, including heart rate, breathing, swal- lowing, vomiting, urination, and orgasm. Thus a significant blow to this region can cause death. Gagging is one of the many reflexes that emerge from the medulla. The second structure of the hindbrain, the pons, plays an important role in sleep

LearnInG tIp: Processing in the Brain

hIndbraIn

MeduLLa: breathing, heart rate, other survival mechanisms

pOns: sleep, arousal, left-right body movement coordination

cerebeLLuM: motor learning, coordination, balance

MIdbraIn substantIa nIGra: initiation of voluntary motor activity

FOrebraIn (subcOrtIcaL structures)

thaLaMus: sensory information (except smell)

hYpOthaLaMus: regulation of body functions (e.g., temperature) and motivation (e.g., hunger, thirst)

hIppOcaMpus: formation of new memories

aMYGdaLa: association of emotions with experiences

basaL GanGLIa: motor planning and movement, reward

FOrebraIn (cOrtIcaL structures)

OccIpItaL LObes: vision

parIetaL LObes: touch, spatial information

teMpOraL LObes: hearing, memory

FrOntaL LObes: planning, movement, complex thought

medulla A hindbrain structure at the top of the

spinal cord; controls survival functions

such as breathing and heart rate.

pons A hindbrain structure above the medulla;

it regulates sleep and arousal and

coordinates movements of the left and

right sides of the body.

54 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Substantia nigra (initiating voluntary movements)

Medulla (heart rate, breathing)

Pons (sleep, arousal)

Cerebellum (balance, motor coordination, motor learning)

cerebellum A hindbrain structure behind the medulla

and pons; this structure is essential for

coordinated movement and balance.

and arousal and in  coordinating movements between the left and right sides of the body (see Figure 2.13).

The cerebellum is a large extension in the hindbrain. It is located behind the medulla and pons (see Figure 2.13). Its size and convoluted surface make it look like an  extra brain. In fact, the name cerebellum comes from the Latin word for “little brain.”

The cerebellum is essential for proper motor function. Damage to the different parts of the cerebellum produces very different effects. Damage to the very bottom causes problems with head tilt and balance. Damage to the ridge that runs up the back of the cerebellum affects walking. Damage to the lobes on either side causes a loss of coordination in the limbs. For example, the person could not reach out smoothly to pick up a pen.

The cerebellum’s most obvious role is in motor learning and motor memory. For example, the cerebellum makes it possible for you to ride a bicycle effortlessly— and to do so while planning your next meal. In fact, the cerebellum may be involved in cognitive processes such as making plans, remembering events, using language, and experiencing emotion.

MIdbraIn The midbrain is located above the pons. It consists of several struc- tures that are involved in the reflexive movement of the eyes and body. One structure in particular, the substantia nigra, is important for making voluntary movements and initiating movements (see Figure 2.13). This region is critical for the production of dopamine, the neurotransmitter that motivates behavior and controls normal motor function. Parkinson’s disease, discussed earlier, is caused by the death of substantia nigra cells and the resulting loss of dopamine produced by those cells. 

Forebrain Subcortical Structures Control Our Motivations and Emotions Above the midbrain is the forebrain. The forebrain includes two main areas: the cerebral cortex and the five subcortical structures (Figure 2.14). The intricate surface that makes up the outermost part of the forebrain is called the cerebral cortex. We will discuss the functions of the cerebral cortex shortly. Below this

Figure 2.13 the hindbrain and the Midbrain This drawing shows where the hindbrain

(medulla, pons, and cerebellum) and the

midbrain (including the substantia nigra)

are located. The view shows the brain as

though you could see inside to its middle.

Cerebral cortex (thought, planning)

Basal ganglia (motor planning and movement, reward)

Thalamus (sensory gateway for seeing, hearing, etc.)

Hypothalamus (regulates body functions and motivates behaviors)

Amygdala (associates emotions with experiences)

Hippocampus (formation of memories)

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 55

structure are the forebrain subcorti- cal regions. This name simply means that these regions are under the cortex.

Some subcortical structures are important for psychological functions. These structures include the thalamus, the hypothalamus, the hippocampus, the amygdala, and the basal ganglia. Some of these structures belong to the limbic system. Limbic is from the Latin word for “border.” The limbic system serves as the border between the parts of the brain that evolved earliest (the hind- brain and the midbrain) and the part that evolved more recently (the cere- bral cortex). The brain structures in the limbic system are especially important for controlling motivated behaviors, such as eating and drinking. These structures are also important for controlling emotions.

thaLaMus The thalamus is the gateway to the cortex (see Figure 2.14). In other words, this structure receives almost all incoming sensory information, organizes it, and relays it to the cortex. The only exception to this rule is the sense of smell. Smell is the oldest and most fundamental sense. From the nerves in the nose, smell has a direct route to the cortex. During sleep, the thalamus partially shuts out incoming sensations to help the person stay asleep.

hYpOthaLaMus The hypothalamus is the brain’s master regulatory structure (see Figure 2.14). It is indispensable to the body’s survival. “Hypo” means below, so the hypothalamus is located below the thalamus. It receives input from almost everywhere in the body and brain, and it sends its influence to almost everywhere in the body and brain. It affects the functions of many internal organs. It also regulates body temperature, body rhythms such as sleeping and waking, blood pressure, and blood glucose (also known as blood sugar). It is also involved in the motivations for many behaviors, including drinking, eating, aggression, and sex.

hIppOcaMpus The hippocampus plays an important role in the formation of new memories (see Figure 2.14). Its name comes from the Greek word for “sea horse,” because of this structure’s sea horse–like shape. The hippocampus seems to form new memories by creating new neural connections within the cerebral cortex for each new experience.

The hippocampus may be involved in how we remember the arrangements of both places and objects in space. For example, it may help us recall how streets are laid out in a city or how furniture is positioned in a room. An interest- ing study to support this theory focused on London taxi drivers. Maguire and colleagues (2003) found that one region of the hippocampus was much larger in London taxi drivers’ brains than in the brains of most other London drivers. London taxi drivers are well known for their expertise. To acquire a commercial license, these taxi drivers must take a rigorous exam testing their knowledge of the city’s streets. Is a person with a large hippocampus more likely to drive a taxi? Or does the hippocampus grow because of navigational experience?

In the Maguire study, the volume of gray matter in the hippocampal region was highly correlated with the number of years of experience as a taxi driver. In

thalamus A subcortical forebrain structure; the

gateway to the brain for almost all

incoming sensory information before that

information reaches the cortex.

hypothalamus A subcortical forebrain structure

involved in regulating bodily functions.

The hypothalamus also influences our

basic motivated behaviors.

hippocampus A subcortical forebrain structure that is

associated with the formation of memories.

Figure 2.14 the Forebrain This drawing shows where the forebrain

regions (the cerebral cortex and the five

subcortical structures) are located. The

view shows the brain as though you could

see inside to its middle.

56 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

(a) (b)

Temporal lobe (hearing, memory)

Parietal lobe (touch, spatial relations)

Frontal lobe (complex thought, planning, movement)

Primary auditory cortex (hearing)

Primary visual cortex (vision)Fusiform face

area (face recognition)

Prefrontal cortex (attention, self-control, social processes)

Primary motor cortex (motor acts)

Primary somatosensory cortex (touch)

Occipital lobe (vision)

other words, it is possible the hippocampus changes with experience. But recall from Chapter 1 that correlation does not prove causation. The Maguire study did not conclude that the hippocampus changes with experience. However, research does show that the hippocampus is important for navigating in our environ- ments (Nadel et al., 2013).

aMYGdaLa If you are like most people, you would probably jump if you encountered a large snake. This response shows your amygdala in action (see Figure 2.14). The name comes from the Latin word for “almond,” because of the structure’s almond-like shape. The amygdala is located immediately in front of the hippocampus. It serves a vital role in learning to associate things in the world (such as a snake) with emotional responses (such as fear). The amygdala also intensifies memory during times of emotional arousal. For example, a frighten- ing experience can be seared into your memory for life (although your memory of the event may not be completely accurate).

The amygdala plays a special role in responses to stimuli that elicit fear. This adaptive function helps protect animals from danger. The amygdala is also involved in evaluating the emotional significance of a facial expression (Adolphs et al., 2005). Imaging studies have found that the amygdala is activated especially strongly in response to a fearful face (Whalen et al., 2001). But the amygdala also functions in the processing of more-positive emotions, including sexual arousal. Hamann and colleagues (2004) have found that activity within the amygdala increases when people view sexually arousing stimuli, such as nude photos or videos of sexual activity. The same study also found that amygdala activation is markedly higher in men. This finding suggests that the amygdala may be involved when men respond more strongly to visual sexual stimuli than women do.

Figure 2.15 Lobes and processing centers of the cerebral cortex (a) This diagram identifies the four lobes of the cerebral cortex. (b) The colored areas in this diagram of the cerebral cortex mark important regions within the lobes. Each region processes

specific information.

amygdala A subcortical forebrain structure that

serves a vital role in our learning to

associate things with emotional responses

and in processing emotional information.

Corpus callosum

Spinal cord

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 57

basaL GanGLIa Before crossing a street, do you automatically look for cars? If so, you most likely learned this habit when you were a child. In drawing on this knowledge and performing this action, you’re relying on your basal ganglia (see Figure 2.14). The basal ganglia are subcortical structures that are crucial for planning and producing movement. There is evidence that damage to the basal ganglia can impair the learning of habits, such as automatically looking for cars.

One structure in the basal ganglia is the nucleus accumbens. This structure is important for experiencing reward and motivating behavior. Think about eating food you like or looking at someone you find attractive. Your thoughts might lead you to want to eat that food or spend time with that person. What makes this happen? Nearly every pleasurable experience activates dopamine neurons in the nucleus accumbens. In other words, the dopamine boost makes you want to eat the food or spend time with the person. One brain imaging study found that viewing expensive sports cars led to greater activation of the nucleus accumbens in men than did viewing less expensive economy cars (Erk, Spitzer, Wunderlich, Galley, & Walter, 2002). The more desirable objects are, the more they activate basic reward circuitry in our brains.

The Cerebral Cortex of the Forebrain Processes Our Complex Mental Activity The outer layer of the forebrain is called the cerebral cortex. This layer gives the brain its distinctive wrinkled appearance (Figure 2.15). (Cortex is the Latin word for “bark.” In reality, the cortex feels more like a hard-boiled egg than tree bark.) In humans, the cerebral cortex is relatively large. If you could flatten it out, the cortex would be about the size of a large sheet of newspaper. However, because it is folded in against itself so many times, the cortex fits within the skull. It is the site of all thoughts, detailed perceptions, and complex behaviors. It enables us to comprehend ourselves, other people, and the outside world.

The cortex is divided into two halves. These halves are called the left hemisphere and the right hemisphere. Each cerebral hemisphere has four areas, which are called lobes: the occipital, parietal, temporal, and frontal lobes. Each lobe has specialized functions (see Figure 2.15a). In addition, areas within each lobe process specific information (see Figure 2.15b). The hemispheres are connected by a structure called the corpus callosum. This massive bridge consists of millions of axons. It allows information to flow between the hemispheres (Figure 2.16).

You might wonder whether the left and right hemispheres serve differ- ent functions. Recall the earlier discussion of Broca’s area and the rela- tionship between the left hemisphere and language. For most people, the left hemisphere is responsible for logical thought and language. Being able to speak and write depends on the left hemisphere. By contrast, the right hemisphere is responsible for spatial relationships, such as understanding a map or locating objects that are around you. Recognizing faces, understanding emotional aspects of language, and abstract thinking involve more processing in the right hemi- sphere. Examining people who had damage to one side of the brain was the initial source of evidence for these patterns. In the 1960s, this book’s coauthor Michael Gazzaniga, working with Nobel laure- ate Roger Sperry, conducted a series of studies on patients whose hemispheres had been separated as part of treatment for epilepsy.

Figure 2.16 the corpus callosum This fibrous structure connects the two

hemispheres of the cerebral cortex.

58 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

(left) (right)

Toes

H ip

A rmTr u n k H e a d

N e c k

S h o

u ld

e r

H a n d

Th um

b

F in

g e rs

Ey e

No se

Fa ce

Primary somatosensory

cortex

Primary motor cortex

Genitals

Foot

Leg Knee

Toes

H ip

A rm Tr

u n k

N e c k

S h o

u ld

e r

H a n d

Thum b

F in

g e rs

Eye Brow

NeckNoseFace

Lips Lips

Tongue Tongue

Ankle

Leg Knee

Teeth Teeth

Jaw Jaw

Gums Gums

Figure 2.17 the primary somatosensory and Motor “homunculus” The cortical representation of the body

surface is organized in strips that run

down the side of the brain. (right) Touch information is processed in the primary

somatosensory cortex. (left) Motor information is processed in the primary

motor cortex.

Studying these split-brain patients revealed important insights into how the two hemispheres are specialized for certain functions. In Chapter 3, you will learn much more about what we have learned from split-brain studies.

LObes OF the cerebraL cOrteX The occipital lobes are at the back portion of the head (see Figure 2.15a). These lobes are devoted almost exclusively to vision, and they include many distinct visual areas. By far the largest of these areas is the primary visual cortex (see Figure 2.15b). The primary visual cortex is the major destination and processor of visual information.

The primary visual cortex is surrounded by a patchwork of secondary visual areas. These areas process various qualities of the visual input, such as its colors, forms, and motions.

The parietal lobes are devoted partially to touch (see Figure 2.15a). Their labor is divided between the left and right cerebral hemispheres. The information received by the hemispheres is actually reversed: The left hemisphere receives touch information from the right side of the body, and the right hemisphere receives touch information from the left side of the body. In each parietal lobe, this sensory information is directed to the primary somatosensory cortex (see Figure 2.15b). The name of this structure might be long and intimidating, but it simply refers to a strip of brain matter in the front part of the lobe, running from the top of the brain down the sides.

In the primary somatosensory cortex, touch information from one body part registers in the cortex near regions where touch information is registered from nearby body parts (Figure 2.17, right side). For example, sensations on the fingers

occipital lobes Regions of the cerebral cortex at the back

of the brain; these regions are important

for vision.

parietal lobes Regions of the cerebral cortex in front of

the occipital lobes and behind the frontal

lobes; these regions are important for the

sense of touch and for picturing the layout

of spaces in an environment.

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 59

register in the cortex near where sensations on the hand are registered. More cortical area is devoted to the body’s more sensitive areas, such as the face and the fingers. As a result, the classic representation of the primary somatosensory area is like a distorted version of the entire body.

This representation of the somatosensory area is known as the somato- sensory homunculus. (Homunculus comes from the Greek word for “ little man.”) The representation is based on mappings by the pioneering neuro- logical researcher Wilder Penfield. Penfield created these mappings as he examined patients who were to undergo surgery for epilepsy (Figure 2.18a). Penfield’s aim was to perform the surgery without damaging brain areas vital for functions such as speech. With the patient awake, Penfield applied a local anesthetic to the scalp. He then electrically stimulated regions of the patient’s brain (Figure 2.18b). During the stimulation, Penfield asked the patient to report what he was experiencing. Penfield’s studies provided important evidence about the amount of brain tissue devoted to each sensory experience.

A stroke or other damage to the right parietal region can result in the neurologi- cal disorder called hemineglect. Patients with this syndrome fail to notice anything on their left sides. While looking in a mirror, they will shave or put makeup on only the right side of the face. If two objects are held up before them, they will see only the one on the right. When asked to draw a simple object, they will draw only its right half (Figure 2.19).

The temporal lobes (see Figure 2.15a) hold the primary auditory cortex (see Figure 2.15b). This brain region is responsible for hearing. In addition, the tempo- ral lobes include visual areas specialized for recognizing detailed objects, such as faces. Also within the temporal lobes are the hippocampus and the amygdala ( both critical for memory, as discussed earlier).

At the intersection of the temporal and occipital lobes is the fusiform face area (see Figure 2.15b). This region is much more active when you look at faces than when you look at other things. Other regions of the temporal lobe are more activated by objects, such as houses or cars, than by faces. If your fusiform face area were damaged, you would have trouble recognizing people but not objects.

Figure 2.18 Mapping the somatosensory homunculus (a) This photograph shows one of Wilder Penfield’s patients immediately before direct stimulation of the brain. (b) Here you can see the exposed surface of the patient’s cortex. The numbered tags mark locations that were electrically stimulated.

(a) (b)

Figure 2.19 hemineglect This drawing was made by a patient with

hemineglect who has damage to the

parietal lobe in the right hemisphere. The

patient did not draw much of the flower’s

left side.

temporal lobes Regions of the cerebral cortex below the

parietal lobes and in front of the occipital

lobes; these regions are important for

processing auditory information and for

perceiving objects and faces.

60 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

The frontal lobes are essential for planning and movement (see Figure 2.15a). The rear portion of the frontal lobes is the primary motor cortex (see Figure  2.15b).  This structure includes neurons that send messages directly to the spinal cord to move the body ’s muscles. The functions of the primary motor cortex are divided down the middle of the body, like those of the primary somatosensory cortex: The left hemisphere controls the right arm, for example, whereas the right hemisphere controls the left arm. So if you are right-handed, you use the primary motor cortex in your left hemisphere to write. If you are left-handed, the opposite is true. You use the primary motor cortex in your right hemisphere to write (see Being a Critical Consumer). In addition, motor infor- mation for a body part is processed in cortical areas that are near regions that process motor acts for nearby body parts (see Figure 2.17, left side). In people with multiple sclerosis, neurons in a specific area of the motor cortex become demyelinated (lose myelin). As a result, the person has trouble moving that specific body part.

carlos was excited to be back in school. He had been an aver-

age student in high school, but after graduation he was just

not ready for college. He spent one very unproductive semes-

ter at state college. Then he spent eight years in the army,

including two tours of duty overseas. Now carlos knew he

was ready for higher education. classes and readings did not

seem like obligations. They were chances to learn new things.

While reading chapter 2 of his psychology textbook,

carlos became interested in brain laterality. How cool is it that the left side of my brain controls the right side of my body and vice versa? carlos was left-handed. from child- hood, he had been able to list famous “southpaws” (Julius

caesar, Napoleon Bonaparte, Marilyn Monroe, and Barack

Obama, to name a few). Now he wondered if being in this

minority (estimated between 5 percent and 30 percent of

people) made him think any differently from people in the

majority. He laughed. Please tell me there is some benefit to never having scissors that suit my hand!

At the Huffington Post, carlos found a news article: “11 little known facts About left-Handers.” He had read

these sorts of stories for years. Would his newly acquired

psychology background help him separate the facts from

the fiction in this article? One of the claims was that “lefties

make better artists.” Is this possible? Does being left-handed really make me a better artist?

Reading the article more closely, he decided this claim was

overstated. According to one scientific study, left-handed

people engage in more-divergent thinking. In other words,

they think outside the box. According to another study, left-

ies appear to be more drawn to careers in the arts, sports,

and information technology. Is that the evidence? These are associations, so being left-handed is linked with creativity.

But these results don’t mean that being left-handed makes me more creative. carlos thought some more. Maybe it’s OK to just have correlational data here. After all, it would be hard to do an experiment on this topic.

carlos now began looking for research that would show a

relationship between handedness and actual brain behavior.

Maybe researchers have shown that left-handed people use the sides of the brain differently than right-handed people do.

Indeed, the same article claimed that “left-handers get

angrier.” That research on left-handedness suggested that

lefties might be more prone to negative emotions. And lefties’

brains can show more imbalance between the right and left

hemispheres when processing negative emotions.

QuestIOn Carlos has discovered evidence that being left-handed is

associated with both creativity and negative emotions.

Why might being left-handed in a right-handed world

make people think differently or become prone to nega-

tive emotions?

beInG a crItIcaL cOnsuMer: What Are the Facts About Brains and “Handedness”?

frontal lobes Regions of the cerebral cortex at the front

of the brain; these regions are important

for movement and complex processes

(rational thought, attention, social

processes, etc.).

Figure 2.20 phineas Gage (a) This recently discovered photo shows Gage holding the rod that passed through

his skull. (b) Here you can see the hole in the top of Gage’s skull. (c) This computer- generated image reconstructs the likely

path of the rod through the skull.

preFrOntaL cOrteX The rest of the frontal lobes consists of the prefrontal cortex (see Figure 2.15b). In humans, this structure occupies about 30 percent of the brain. Scientists have long thought that our extraordinarily large prefrontal cortex makes humans unique in the animal kingdom. There is recent evidence, however, that what separates humans from other animals is not how much of the brain the prefrontal cortex occupies. Instead, the difference between the human brain and the brains of other animals is in the complexity and organiza- tion of these neural circuits (Bush & Allman, 2004; Schoenemann, Sheehan, & Glotzer, 2005).

The entire prefrontal cortex is critical for rational thought. It is also especially important for many aspects of human social life. It provides both our sense of self and our capacity to empathize with others or feel guilty about harming them. Particular parts of the prefrontal cortex are responsible for directing and main- taining attention, keeping ideas in mind while distractions bombard us from the outside world, and developing and acting on plans.

Psychologists have learned a great deal of what they know about how brain regions work by carefully studying people whose brains have been damaged by disease or injury. Perhaps the most famous historical example of brain damage is the case of Phineas Gage (Figure 2.20a). The first modern theories of the pre-frontal cortex’s role in both personality and self-control were based on Gage’s case.

In 1848, Gage was a 25-year-old foreman on the construction of Vermont’s Rutland and Burlington Railroad. One day, he dropped a tool called a tamping iron, which was over a yard long and an inch in diameter. The iron rod hit a rock, ignit- ing some blasting powder. The resulting explosion drove the rod into his cheek, through his frontal lobes, and out through the top of his head (Figure 2.20b). Gage was still conscious as he was hurried back to town on a cart. Able to walk, with assistance, upstairs to his hotel bed, he wryly remarked to the awaiting physician, “Doctor, here is business enough for you.” He said he expected to return to work in a few days. In fact, Gage lapsed into unconsciousness and remained unconscious for two weeks.

Physically, Gage recovered remarkably well. Unfortunately, the accident led to major personality changes. Whereas the old Gage had been regarded by his

HOW DO THE PARTS Of OUR BRAINS fUNcTION? ■ 61

62 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

employers as “the most efficient and capable” of workers, the new Gage was not. As one of his doctors later wrote,

The equilibrium or balance, so to speak, between his intellectual faculties and animal propensities seems to have been destroyed. He is fitful, irreverent, indulging at times in the grossest profanity . . . impatient of restraint or advice when it conflicts with his desires. . . . A child in his intellectual capacity and manifestations, he has the animal passions of a strong man.

In sum, Gage was “no longer Gage.” He could not get his foreman’s job back. Instead, Gage exhibited himself in various New England towns and at the New York Museum (owned by the circus showman P. T. Barnum). After a decade, Gage’s health began to decline, and in 1860 he started having epileptic seizures and died within a few months. At first, the medical community used Gage’s recovery to argue that the entire brain works uniformly and that the healthy parts of Gage’s brain had taken over the work of the damaged parts. However, Gage’s severe psychologi-

cal impairments eventually led the group to recognize that some areas of the brain have specific functions.

Reconstruction of Gage’s injury clearly shows that the prefrontal cortex was the area most damaged by the tamping rod ( Damasio, Grabowski, Frank, Galaburda, & Damasio, 1994; Figure 2.20c). Recent studies of patients with similar injuries reveal that this brain region is particularly concerned with social processes. For example, it is responsible for following social norms, understanding what other people are thinking, and feeling emotionally connected to others. People with damage to this region do not typically have problems with memory or general knowledge. They often have serious distur- bances in their ability to get along with others.

In the late 1930s, mental health professionals developed a new treatment for many patients with psychological disorders—especially patients who could not control their emotions. The procedure was called a lobotomy, and it was a delib- erate damaging of the prefrontal cortex (Figure 2.21). This form of brain surgery generally left patients lethargic and emotionally flat. As a result, the patients were much easier to manage in mental hospitals. But it also left them disconnected from their social surroundings, as Gage was. Most lobotomies were performed in the late 1940s and early 1950s. With the arrival of drugs to treat psychological disor- ders, the lobotomy was phased out.

■ The hindbrain includes three structures: the brain stem, which regulates basic

survival functions; the pons, which regulates sleep and arousal and coordinates

body movements; and the cerebellum, which is essential for movement and

control of balance.

■ The midbrain includes the substantia nigra, which is responsible for initiating

voluntary motor activity.

■ Together, the five subcortical structures of the forebrain control memory

formation, emotions, and motivated behaviors.

■ The four lobes of the forebrain and associated cortical areas are responsible

for the most complex processing.

2.2 checkpOInt: How Do the Parts of Our Brains Function?

Figure 2.21 Lobotomy This photo shows Dr. Walter freeman performing

a lobotomy in 1949.

HOW DO OUR BRAINS cOMMUNIcATE WITH OUR BODIES? ■ 63

2.3 How Do Our Brains Communicate With Our Bodies?

When you decide to move your arm, most of the time your arm moves. When you watch a sad movie, your eyes may produce tears. How do the parts of your body get the information from your brain that makes them respond the way they do?

Recall that the nervous system consists of the central nervous system (the brain and the spinal cord) and the peripheral nervous system (all the nerves in the rest of the body; see Figure 2.2). The peripheral nervous system transmits a variety of information to the central nervous system. It also responds to messages from the central nervous system to perform specific behaviors or make bodily adjust- ments. The peripheral nervous system has two primary components: the somatic nervous system and the autonomic nervous system. In producing psychological activity, the nervous system also interacts with the hormones of the endocrine system. Let’s examine how these various interactions affect thought and behavior.

Our Somatic Nervous System Detects Sensory Input and Responds The somatic nervous system transmits signals to and from the central nervous system through nerves. Specialized receptors in the skin, muscles, and joints send sensory information to the spinal cord, which relays it to the brain. In addition, the central nervous system sends signals through the somatic nervous system to muscles, joints, and skin to initiate or inhibit movement.

To get a sense of how fast this process can work, think of the last time you touched something hot or accidentally touched a sharp object, such as a tack. Those signals triggered your body’s nearly instantaneous sensory experience of the impact. In the case of the sharp tack, these signals would immediately trigger movement of your finger off the painful object.

This process controls movement. For instance, suppose you are using a pen to take notes. You are contracting and relaxing your hand muscles and finger muscles to adjust your fingers’ pressure on the pen. When you want to use the pen, your brain sends messages to your finger muscles so they move in specific ways. Receptors in both your skin and your muscles send back messages to help determine how much pressure is needed to hold the pen. This simple act of using a pen is a remarkable

LearnInG GOaLs readInG actIvItIes

a. Remember the key terms about the peripheral nervous

system and the endocrine system.

list all of the boldface words and write down their

definitions.

b. Analyze how the somatic nervous system processes

information.

Identify how your somatic nervous system functions

when you touch a hot pan.

c. Apply the autonomic nervous system to your life.

Provide examples of two experiences you have had, one

processed by the sympathetic system and one by the

parasympathetic system.

d. Understand the endocrine system.

Summarize in your own words how the testes and

ovaries secrete certain hormones that influence sexual

development and behavior.

somatic nervous system A part of the peripheral nervous system;

this part transmits sensory signals and

motor signals between the central nervous

system and the skin, muscles, and joints.

64 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

symphony of neural communication. Yet most of us employ motor control so easily that we rarely think about it. Some movement does, in fact, occur without infor- mation ever being processed in the brain. These movements are reflexes, such as the knee-jerk reflex discussed in Has It Happened to You? For each reflex action, a handful of neurons simply convert sensation into action based on processing only within the spinal cord.

Our Autonomic Nervous System Regulates the Body Automatically The second major component of the peripheral nervous system is the autonomic nervous system (see Figure 2.2). As its name suggests, the autonomic nervous system automatically regulates the body’s internal environment (see the Learning Tip). It accomplishes this regulation by stimulating glands (such as sweat glands) and by maintaining internal organs (such as the heart). Nerves in the autonomic nervous system also carry signals from the glands and internal organs to the central nervous system. These signals provide information about, for example, the fullness of your stomach or how anxious you feel.

The autonomic nervous system has two divisions: the sympathetic nervous system and the parasympathetic nervous system (see Figure 2.2). Both divisions control the activity of organs and glands. They do so by providing signals that travel from the central nervous system to the organs and glands and back again (Figure 2.22).

Figure 2.22 sympathetic and parasympathetic divisions of the autonomic nervous system

Eyes

The sympathetic division of the nervous system prepares the body for action.

The parasympathetic division returns the body to a resting state.

Lungs

Heart

Stomach, intestines

Pupils dilate.

Respiration increases.

Digestion decreases. Digestion increases.

Heart rate increases.

Heart rate decreases.

Respiration decreases.

Pupils contract.

autonomic nervous system A part of the peripheral nervous system;

this part transmits sensory signals and

motor signals between the central nervous

system and the body’s glands and internal

organs.

has It happened

tO YOu?

Knee Jerk

Have you ever had your knee-

jerk reflex tested at the doctor’s

office? If so, you probably sat on

a table. When the doctor used a

tool to tap a spot just below your

knee, your leg involuntarily jerked

up. This procedure illustrates how

your somatic nervous system

allows reflexes to occur: Nerves

process information about the tap,

and signals are processed through

the spinal cord. This processing

causes your leg to move. The

communication happens in an

instant because the signals never

have to reach your brain. Instead,

the reflex signals are processed

only in the spinal cord.

HOW DO OUR BRAINS cOMMUNIcATE WITH OUR BODIES? ■ 65

endocrine system A communication system that uses

hormones to influence thoughts and

actions.

hormones chemical substances, released from

endocrine glands, that travel through the

bloodstream to targeted tissues; the

tissues are later influenced by the

hormones.

LearnInG tIp: Remembering the Autonomic Nervous System

When YOu see pLease thInk MeanInG

Autonomic nervous system Automatic processes Processes that are out of a person’s control, such as blood pressure, heart rate, and respiration.

To understand these signals, imagine that you hear a fire alarm. In the second after you hear the alarm, signals go out to parts of your body that automatically prepare them for action. As a result, blood flows to the muscles that move your skeleton. Epinephrine is released, increasing your heart rate and blood sugar. Your lungs take in more oxygen. Your pupils dilate to maximize visual sensitivity. You perspire to keep from overheating. These preparatory actions are prompted by the autonomic nervous system’s sympathetic division. If a fire exists, you are physically prepared to flee. If the alarm turns out to be false, your heart will return to its normal steady beat, your breathing will slow, and you will stop perspiring. This return to a normal state will be prompted by the parasympathetic division of the autonomic nervous system. Most of your internal organs are controlled by inputs from sympathetic and parasympathetic systems. The more aroused you are, the greater the sympathetic system’s dominance.

It doesn’t take a fire alarm to activate your sympathetic nervous system. When you meet someone you find attractive, for example, your heart beats quickly, you perspire, you might start breathing heavily, and your pupils dilate. These responses occur because sexual arousal has activated the sympathetic division of the autonomic nervous system. The responses provide nonverbal cues during social interaction. The sympathetic nervous system is also activated by psychological states such as anxi- ety or unhappiness. If people worry a great deal or do not cope well with stress, their bodies are in a constant state of arousal. Important research in the 1930s and 1940s by Hans Selye demonstrated that chronic activation of the sympathetic nervous system is associated with such medical problems as heart disease and asthma.

The Endocrine System Affects Our Behavior Through Hormones Like the nervous system, the endocrine system is a communication network that influences thoughts and actions. The main difference between the two systems is in their forms of communication: The nervous system uses electrochemical signals, and the endocrine system uses chemicals called hormones. Both systems work together to regulate psychological activity. For instance, the brain receives informa- tion from the nervous system about potential physical or psychological threats. The brain communicates with the endocrine system to release hormones that prepare the organism to deal with those threats.

hormones are chemical substances released into the bloodstream by endocrine glands. The endocrine glands include the pineal gland (see Chapter 3), the adrenal glands (see Chapter 11), the pituitary gland, the thyroid, and the testes or ovaries (Figure 2.23). Once released, hormones travel through the bloodstream until they reach their target tissues. Because they travel through the bloodstream, hormones can take from seconds to hours to have an effect. Once hormones are in the

66 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Thyroid (controls how body

burns energy)

Adrenal (governs immune

system)

Ovaries (in�uence sexual development and sexual behavior

in females)

Testes (in�uence sexual development and sexual behavior

in males)

Pineal (governs bodily rhythms)

Pituitary (governs release

of hormones)

Figure 2.23 the Major endocrine Glands The glands in the endocrine system work

with the nervous system by releasing

chemicals that influence thinking and

behavior.

bloodstream, their effects can last for a long time and affect multiple body regions. Many different kinds of hormone action take place. Let’s consider two types.

hOrMOnes, seXuaL deveLOpMent, and behavIOr One example of hormonal influence is our sexual development and sexual behavior. The main endo- crine glands influencing sexual behavior are the gonads: the testes, in males, and the ovaries, in females. Although people often talk about “male” and “female” hormones, both males and females produce both hormones. What differs is the quantity: Andro- gens, such as testosterone, are more prevalent in males. Estrogens, such as estradiol, are more prevalent in females. Gonadal hormones influence the development of secondary sex characteristics (e.g., breast development in females, growth of facial hair in males). Gonadal hormones also influence adult sexual behavior. You will learn more about this in Chapter 10.

hOrMOnes and phYsIcaL GrOWth Growth hormone (GH) prompts bone, cartilage, and muscle tissue to grow or helps them regenerate after injury. Since the 1930s, some people have used GH to increase body size and strength. Many athletes have sought a competitive advantage by using GH. For example, in early 2013 the legendary cyclist Lance Armstrong admitted to using GH and other hormones, including testosterone, to gain a competitive advantage. In an interview with Oprah Winfrey, Armstrong claimed it was impossible for any cyclist to win a major championship without doping (Figure 2.24).

HOW DO NATURE AND NURTURE AffEcT OUR BRAINS? ■ 67

2.4  How Do Nature and Nurture Affect Our Brains?

LearnInG GOaLs readInG actIvItIes

a. Remember the key terms about how nature and nurture

affect the brain.

list all of the boldface words and write down their

definitions.

b. Apply the effects of genetics to your life. Describe one of your physical or psychological

characteristics that was primarily influenced by genetics.

c. Understand how behavioral genetics studies the

interaction of genes and environment. Summarize the results of twin studies in your own words.

d. Apply the effects of environment to your life. Describe one of your characteristics that was primarily

influenced by the environment in which you were raised.

Figure 2.24 Growth hormone and cycling In January 2013, lance Armstrong

appeared on The Oprah Winfrey Show to admit using doping techniques to enhance

his cycling performance.

As you know from the chapter’s opening story, Jack Osbourne is experiencing the symptoms of multiple sclerosis (MS). Did he inherit this condition from his parents? Could environmental influences, such as childhood nutrition, be involved? We don’t know exactly what causes MS. Some researchers believe that unknown environ- mental triggers produce the condition and that people inherit a predisposition to

■ The peripheral nervous system includes the somatic nervous system and the

autonomic nervous system.

■ The somatic nervous system allows movement of the muscles and joints.

■ The autonomic nervous system automatically regulates the body’s internal

environment through the sympathetic division and the parasympathetic division.

■ The endocrine system includes glands that produce and release hormones

that travel through the bloodstream and influence a variety of processes.

2.3 checkpOInt: How Do Our Brains Communicate With Our Bodies?

68 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

respond to those triggers. Whatever the cause, how Osbourne copes with MS will depend at least in part on his psychological makeup.

So far, we have looked at the basic biological processes underlying psychological functions. Now we return to the question of nature or nurture. Recall from Chapter 1 that nature and nurture always work together to make us who we are. At the moment of conception, we inherit the genes we will possess for the rest of our lives. But how much of who we are depends on our genetic makeup? And how much of who we are depends on environmental influences, such as the household and the culture we are raised in? To begin answering these questions, see Try It Yourself.

Until fairly recently, genetic research focused almost entirely on whether people possessed certain types of genes. For example, did they have the genes for particular psychological disorders? It is impor- tant to discover the effects of individual genes. However, this approach misses the critical role of environmental factors in how genes work. Geneti- cists still study the inheritance of particular charac- teristics, but they also study gene expression. They examine the processes that turn genes “on” and “off.” Their research reveals that our environment affects

how our genes are expressed and therefore how they influence our thoughts, feel- ings, and behavior.

Genes Affect Our Thoughts and Behavior Lenore Wexler had so little control over her movements that she stumbled across the street. A policeman watched her and then asked her why she was drinking so early in the day. Wexler was not drinking, however. She was showing the first symptoms of Huntington’s disease, a disorder that affects the nervous system and damages specific parts of the brain (Figure 2.25). The damage results in abnor- mal body movements such as a jerky walk; loss of ability to walk, write, or speak; emotional and personality changes, such as extreme anxiety and depression; dementia; and eventually death.

Lenore Wexler was the mother of Nancy Wexler, who is a neuropsycholo- gist and geneticist. After her mother’s death from Huntington’s in 1978, Wexler dedicated herself to finding the gene for the disorder that had killed her mother. Though knowing which genes are involved in Huntington’s has not yet led to a cure, it can help people decide whether they want to take the risk of having children and possibly passing along the gene. If a parent has Huntington’s, that parent’s biological child has a 50/50 chance of developing the disorder. Because symptoms often do not appear before the affected person is around 40, many of those with Huntington’s often have children before they realize they have the genetic disorder. Thanks to the work of Nancy Wexler and her colleagues, people who have relatives with Huntington’s can now take a genetic test to find out if they carry the gene for the disease and then decide whether they want to risk having children.

Figure 2.25 huntington’s disease affects the brain, thoughts, and behavior Huntington’s disease is an extreme

example of how we are affected by our

genes.

trY It YOurseLF: Genetic Matching

Shown in the top row are two couples. Below are four

children. Try to match which child comes from which

parents.

Answer: The boy and the girl at the ends of the bottom

row are children of the parents at the top right. The two

girls in the middle of the bottom row are the children of

the parents at the top left.

HOW DO NATURE AND NURTURE AffEcT OUR BRAINS? ■ 69

We all know that genes control many physical characteristics, such as sex and eye color. The inheritance of Huntington’s helps us understand that genes also influence our predispositions to particular diseases, including cancer and alco- holism. What about other factors, such as personality, intelligence, and athletic talent? There, too, genes have their influence. So can genes influence individual choices, such as whether we will get divorced or what careers we have?

Increasingly, research indicates that genes lay the groundwork for many human traits. From this perspective, people are born essentially like undeveloped photo- graphs: The image is already captured, but the way it eventually appears can vary based on the development process. Your genetic makeup is called your genotype. The geno- type is set at the moment of conception and never changes. Your observable physical and psychological characteristics are called your phenotype. These factors are influ- enced in part by the genotype. They are also affected by environmental factors. In other words, they can change. Your current height—part of your phenotype—is influenced by your genotype. It was also influenced by your environment, such as childhood diet.

Suppose a person inherits a predisposition to alcoholism (nature). If she is raised in a nondrinking environment and spends time with only moderate social drinkers (nurture), that predisposition may never be expressed. Psychologists study the ways that nature, nurture, and their combination affect psychological characteristics. In other words, they study the ways that genes are expressed in distinct environments.

Genes Interact With Environment to Influence Us “I’m so different from the rest of this family! I must be adopted!” Did you ever think that when you were a child? Most of us, at one time or another, have marveled at how different siblings can be. Even siblings raised around the same time and in the same household have their individual appearances, individual personalities, and so on. The differences are to be expected, however.

Siblings always share some genes and often share much of their environment. But most siblings do not have identical genes or identical life experiences. Within the household and outside it, environments differ subtly and not so subtly. Siblings have different birth orders. Their mother may have consumed different foods and other substances during the different pregnancies. The siblings may have differ- ent friends and teachers. Their parents may treat them differently. The study of how genes and environment interact to influence psychological factors is known as behavioral genetics. Scientists in this field use two methods to assess the degree to which traits are inherited: twin studies and adoption studies.

Twin studies compare similarities between different types of twins to deter- mine the genetic basis of specific traits. Monozygotic twins are identical. They result from one zygote (fertilized egg) dividing in two (Figure 2.26a). Because they come from the same fertilized egg, both twins have the same genetic makeup. dizygotic twins are sometimes called fraternal or non-identical twins. They result when two separately fertilized eggs develop in the mother’s womb simultaneously (Figure 2.26b). Because they come from two separately fertilized eggs, these twins are no more similar genetically than any other pair of siblings.

How do researchers use this information to judge genetic influence? They focus on a specific trait. They compare how similar monozygotic twins are in pheno- types (observable traits and characteristics) with how similar dizygotic twins are. The increased similarity in that trait is considered most likely due to genotypes (genetic influences).

genes The units of heredity, which partially

determine an organism’s characteristics.

monozygotic twins Identical twins; these siblings result from

one zygote splitting in two, so they share

the same genes.

dizygotic twins fraternal twins; these siblings result from

two separately fertilized eggs, so they are

no more similar genetically than non-twin

siblings are.

70 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

Adoption studies compare the similarities between biological relatives and adoptive relatives. Adopted nonbiological siblings may share similar home environ- ments, but they will have different genes. Therefore, researchers assume that simi- larities among adopted siblings who are not biologically related have more to do with environment than with genes. However, growing up in the same home turns out to have relatively little influence on many traits, such as personality.

One way to conduct a study is to compare twins who have been raised together with twins who were raised apart. In a classic study, Thomas Bouchard and his colleagues at the University of Minnesota identified more than 100 pairs of identi- cal and fraternal twins, some raised together and some raised apart (Bouchard et al., 1990). The researchers examined a variety of these twins’ characteristics, includ- ing intelligence, personality, well-being, achievement, alienation, and aggression. The general finding from the Minnesota Twin Project was that identical twins, whether raised together or not, were likely to be similar.

The “Jim twins” were among the most famous case studies to emerge from this project. These twin brothers were separated at birth and raised by different fami- lies. Both families named their new son James. What’s more, each James went on to marry a woman named Linda, divorce Linda and marry a woman named Betty, name a son James Alan (or James Allen), and name a dog Toy. On top of that, both twins were part-time law enforcement officers who drove Chevrolets and vaca- tioned in Florida. They were the same height and weight, chain-smoked the same brand of cigarettes, and drank the same brand of beer. No one would seriously suggest there are genes for naming dogs Toy or for marrying and divorcing women named Linda. However, the many similarities in the Jim twins’ lives point to the strong genetic influences in shaping personality and behavior.

Figure 2.26 twins (a) Identical twins result when one fertilized egg splits in two. These

identical twins are Dean caten and

Dan caten, who are both fashion

designers.

(b) fraternal twins result when two separate eggs are fertilized at the

same time. These fraternal twins,

Denise and Michael, appeared in the

2011 documentary Lone Twin.

Two sperm fertilize two eggs …

… which become two zygotes.

(b) Dizygotic (fraternal) twins

One sperm fertilizes one egg …

… and the zygote splits in two.

(a) Monozygotic (identical) twins

HOW DO NATURE AND NURTURE AffEcT OUR BRAINS? ■ 71

plasticity A property of the brain that causes it to

change through experience, drugs, or

injury.

(b)

(a)

Figure 2.27 Michelle Mack and a case of extreme plasticity (a) While in her mother’s womb, Michelle suffered a stroke that obliterated her left

hemisphere (shown here as the black area

on the right). (b) Over time, Michelle’s right hemisphere took over the duties of

the left hemisphere—language production

and moving the right side of the body—to

a surprising extent. Michelle’s case shows

the plasticity of the brain.

Some critics have argued that most of the adopted twins in the Minnesota study were raised in relatively similar environments. This similarity came about, in part, because adoption agencies try to match the child to the adoptive home. But this argument does not explain the case of the identical twins Oskar Stohr and Jack Yufe (Bouchard et al., 1990). Oskar and Jack were born in Trinidad in 1933. Oskar was raised a Catholic in Germany and eventually joined the Nazi Party. Jack was raised in the Jewish faith in Trinidad and lived for a while in Israel. Few twins have such differ- ent backgrounds. Yet when they met at an interview for the study, Oskar and Jack were wearing similar clothes, exhibited similar mannerisms, and shared odd habits, such as flushing the toilet before using it, dipping toast in coffee, storing rubber bands on their wrists, and enjoying startling people by sneezing loudly in elevators.

Critics feel that nothing more than coincidence is at work in these case stud- ies. They argue that any two people of the same age would exhibit many surprising similarities just by coincidence, even though their lives differed in most other ways. Studies also fail to examine the many ways these twins differ on key traits. But twins and other relatives share similarities beyond coincidental attributes and behavior quirks. For instance, intelligence and personality traits such as shyness tend to run in families, indicating a strong genetic component.

Environment Changes Our Brains When Michelle Mack was a youngster, her parents realized that she was different from other children. They couldn’t explain these differences. When Michelle was 27 years old, they learned that she was missing the left hemisphere of her brain (Figure 2.27a). Doctors suspected that Michelle’s condition was the result of a stroke she experienced in the womb.

Without a left hemisphere, Michelle should have shown severe deficits in skills processed in that half of the brain. For example, the left hemisphere controls language, and it controls motor actions for the right side of the body. Losing a hemi- sphere as an adult would result in devastating loss of function. But Michelle’s speech is only minimally affected. And she can move the right side of her body, although with some difficulty (Figure 2.27b). Michelle is able to lead a surprisingly independent life. She graduated from high school, has a job, pays her bills, and does chores. Where did her capabilities come from? Her right hemisphere developed language process- ing capabilities as well as functions that ordinarily occur across both hemispheres.

Michelle Mack’s case shows that nurture can influence nature. Over time, Michelle interacted with the world. Her experiences enabled her brain to reorganize itself. Her right hemisphere took over processing for the missing left hemisphere. In fact, despite the great precision and the specificity of its connections, the brain is extremely adapt- able. Over the course of development, throughout our constant stream of experience, and after injury, the brain continually changes. This property is known as plasticity. It reflects the interactive nature of biological and environmental influences.

strenGthenInG eXIstInG cOnnectIOns Brain plasticity is what allows us to learn. Throughout life, we learn new things that we remember. All our memo- ries are reflected in the brain’s physical changes. Psychologists now believe that the changes are mainly in the strength of existing connections. One possibility is that when two neurons fire simultaneously, the connection between them strengthens. The strengthened connection then makes these neurons more likely to fire together in the future. By contrast, the connection between two neurons tends to get weaker if the neurons do not keep firing simultaneously. This theory can be summarized by the catchphrase neurons that fire together, wire together.

72 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

braIn reOrGanIZatIOn Sometimes, the brain undergoes some reorganiza- tion, which is another example of brain plasticity. That is, entirely new connec- tions develop between neurons. This new growth is a major factor in recovery from brain injury. Following an injury in the cortex, the surrounding gray matter assumes the function of the damaged area. Think of the healthy gray matter as a local business scrambling to pick up the customers of a newly closed competitor. The remapping seems to begin immediately, and it continues for years. Such plas- ticity involves all levels of the central nervous system, from the cortex down to the spinal cord.

Brain reorganization is much more common in children than in adults. As an extreme example, consider young children who have epilepsy so severe that it para- lyzes one or more of their limbs. To control the epilepsy, surgeons may remove an entire cerebral hemisphere. Just as in the case of Michelle Mack, the remaining

Have you been diagnosed with a learning disability? Do you suspect you

might have one, such as dyslexia, that might give you trouble with read-

ing, spelling, or writing? According to the National center for learning

Disabilities (2009), a learning disability is a “neurological disorder that

affects the brain’s ability to receive, process, store, and respond to infor-

mation.” The new academic and organizational challenges of college

might make the disability more apparent. But a learning disability isn’t

a recipe for failure. Many people with learning disabilities become very

successful. for example, the celebrity chef Jamie Oliver has dyslexia.

If you have a learning disability or suspect you have one, the first thing

to do is get in touch with your campus’s disability support services staff or

a member of the student affairs staff (e.g., the dean of students, a direc-

tor of residence life, or a mental health counselor on your campus). Don’t

delay out of fear of embarrassment or shyness. These people will help you

get access to resources you can use if and when you need them (such as

when the workload becomes very intense).

If your learning disability is verified, disability support staff will work

with you to determine what is needed to level the playing field for you.

What does “level the playing field” mean? Imagine if one football team

had to play blindfolded while the opposing team could see perfectly. The

game would be unfair for the blindfolded team. Thankfully, students with

learning disabilities do not have to go through college wearing their own

versions of blindfolds. Schools must provide equal opportunity to the

benefits of education for individuals with learning disabilities.

Given your particular situation, some types of accommodations will

be helpful and others will not. Disability support office staff will let your

professors know whether you are entitled to a specific type of accom-

modation. for example, you might need extra time to complete an exam.

Importantly, they will not tell your professors about the specific nature

of your learning disability. They will simply note that you have one. If you

wish, you can also speak directly with individual professors about your

learning disability and the kinds of resources likely to help you. linda

Tessler, a psychologist who works with people with learning disabilities,

writes:

It must be clear that you are not asking for standards to be lowered.

you are using tools to help you perform. To pass, you must perform

the task that your classmates perform. you may, however, need to

get there in a different way. (Tessler, 1997)

Will a learning disability prevent you from succeeding? Not if you

can help it, and you can help it by advocating for yourself. line up the

resources you need to ensure that you are able to succeed.

usInG psYchOLOGY

In YOur LIFe:

How Can I Overcome a Learning Disability and Succeed?

HOW DO NATURE AND NURTURE AffEcT OUR BRAINS? ■ 73

■ Both genes and environment affect who we are and what we do.

■ The genes we inherit from our parents affect our physical attributes and the

ways we think and behave.

■ Behavioral genetics uses twin studies to examine how genes and environment

interact to influence mental activity and behavior.

■ Environment affects brain function and psychological characteristics through

plasticity, strengthening neural connections, and brain reorganization.

2.4 checkpOInt: How Do Nature and Nurture Affect Our Brains?

hemisphere eventually takes on most of the lost hemisphere’s functions. The chil- dren regain almost complete use of their limbs. If this procedure were performed on adults, however, the lack of a cerebral hemisphere would result in severe motor deficits. With less chance of brain reorganization, the adults would lose all the func- tions of the missing hemisphere.

Plasticity is among the many fascinating aspects of the brain that psychologists and neuroscientists have discovered over the last several decades. This is an excit- ing time in psychology, with researchers mapping out how various brain regions are connected and how they work together to produce behavior and mental activ- ity. To achieve this mapping, the Human Connectome Project was launched in 2010 as a major international research effort involving collaborators at a number of universities. Greater knowledge of brain connectivity may be especially useful for understanding how brain circuitry changes in psychological disorders. In 2014, U.S. president Barack Obama announced $ 300 million in funding for the BRAIN Initia- tive, which seeks to further the understanding of brain function. Specifically, this initiative aims to help researchers learn about brain disorders, such as Alzheimer’s and Parkinson’s disease, as well as develop tools to study basic brain processes.

74 ■ chapter 2 THE ROlE Of BIOlOGy IN PSycHOlOGy

BIG QUESTION LEARNING GOALS

a. Remember the key terms about the divisions of the nervous system and neurons.

b. Apply the three functions of the nervous system to your own life.

c. Analyze the three steps in neural communication.

d. Apply neurotransmitters to your life.

2.1 How Do Our

Nervous Systems

Affect Thinking and

Behavior?

a. Remember the key terms about brain regions and processes.

b. Apply the three main brain divisions to your own life.

c. Remember the five forebrain subcortical regions.

d. Understand the four lobes of the cerebral cortex.

2.2 How Do the Parts

of Our Brains

Function?

a. Remember the key terms about the peripheral nervous system and the endocrine system.

b. Analyze how the somatic nervous system processes information.

c. Apply the autonomic nervous system to your life.

d. Understand the endocrine system.

2.3 How Do Our Brains

Communicate

With Our Bodies?

a. Remember the key terms about how nature and nurture affect the brain.

b. Apply the effects of genetics to your life.

c. Understand how behavioral genetics studies the interaction of genes and environment.

d. Apply the effects of environment to your life.

2.4 How Do Nature

and Nurture

Affect Our Brains?B IG

P IC

T U

R E

BIG PIcTURE ■ 75

KEY TERMS CHECKPOINT

■ The central nervous system processes information in the brain and the spinal cord. The peripheral nervous system processes information in the soft organs.

■ The nervous system has three primary tasks: It receives information, it integrates that information, and it passes signals to other neurons to allow thought and action.

■ Neurons are the basic units of the nervous system.

■ changes in a neuron’s electrical charge elicit an action potential. The action potential causes the release of neurotransmitters that are received by other neurons.

■ Neurons communicate with each other through neurotransmitters. Each particular neurotransmitter has specific effects on thought and behavior.

nervous system central nervous system peripheral nervous

system neurons dendrites cell body axon synapse action potential neurotransmitters

■ The hindbrain includes three structures: the brain stem, which regulates basic survival functions; the pons, which regulates sleep and arousal and coordinates body movements; and the cerebellum, which is essential for movement and control of balance.

■ The midbrain includes the substantia nigra, which is responsible for initiating voluntary motor activity.

■ Together, the five subcortical structures of the forebrain control memory formation, emotions, and motivated behaviors.

■ The four lobes of the forebrain and associated cortical areas are responsible for the most complex processing.

Broca’s area medulla pons cerebellum thalamus hypothalamus hippocampus amygdala occipital lobes parietal lobes temporal lobes frontal lobes

■ The peripheral nervous system includes the somatic nervous system and the autonomic nervous system.

■ The somatic nervous system allows movement of the muscles and joints.

■ The autonomic nervous system automatically regulates the body’s internal environment through the sympathetic division and the parasympathetic division.

■ The endocrine system includes glands that produce and release hormones that travel through the bloodstream and influence a variety of processes.

somatic nervous system autonomic nervous system endocrine system hormones

■ Both genes and environment affect who we are and what we do.

■ The genes we inherit from our parents affect our physical attributes and the ways we think and behave.

■ Behavioral genetics uses twin studies to examine how genes and environment interact to influence mental activity and behavior.

■ Environment affects brain function and psychological characteristics through plasticity, strengthening neural connections, and brain reorganization.

genes monozygotic twins dizygotic twins plasticity

For a self-quiz on this chapter, go to the back of the book and find Appendix B: Quizzes.

3Consciousness The snowboard champion Kevin pearce, the Arizona congresswoman Gabrielle Giffords, and many

military personnel who have served in Iraq and Afghanistan—what do these people have in common? All have

suffered traumatic brain injury, or TBI, a condition in which a person’s brain is damaged by an external force,

such as a violent blow, or penetration by an object, such as a bullet. The consequences of TBI vary, but victims

are often in a coma for varying lengths of time. TBI is not the only situation in which people may be in a coma; a

comatose state may also result from particular diseases and medical events, such as a stroke. What does it mean

to be in a coma? Is the person conscious at all? Is he aware of his surroundings? Can she think and feel? There

are no simple answers to these questions.

77

BIG QUESTIONS 3.1 What Does It Mean to Be Conscious?

3.2 How Does Sleep Affect Consciousness?

3.3 What Is an Altered State of Consciousness?

3.4 How Do Drugs Alter Consciousness?

78 ■ chapTer 3 CONSCIOUSNESS

Consider the case of Martin Pistorius, who at age 12 suffered a mysterious

illness and fell into a coma. After about two years, he started to wake up,

but was unable to respond in any way. He was aware of everything going on

around him, but nobody realized it. He was left to watch television reruns

of Barney the purple dinosaur for hour after hour, day after day. To this day,

he hates Barney. After nearly a decade, he was able to make small head

movements, but no one knew he was making them on purpose. An atten-

tive health care worker noticed that he seemed to be trying to communi-

cate and arranged for testing, which revealed that Martin was mentally alert

and able to move his eyes in response to questions. By age 26, he could

use a computer to speak. He recovered enough to graduate college, write

the best-selling memoir Ghost Boy (Pistorius, 2013), and get married. His

book describes the decade where he was unable to let anyone know he was

conscious. He writes in the preface, “My mind was trapped inside a useless

body, my arms and legs weren’t mine to control, and my voice was mute. I

couldn’t make a sign or a sound to let anyone know I’d become aware again.

I was invisible—the ghost boy” (p. x; Figure 3.1a–b).

In other cases, it is hard to tell whether people in comas are conscious. Terri

Schiavo, a young woman in Florida, spent more than 15 years in a coma. She

went into the coma after her heart temporarily stopped, resulting in a lack of

oxygen to her brain for several minutes. Terri seemed to respond to external

stimuli and even laughed sometimes, making some people believe she was

conscious. But brain scans revealed that the parts of her brain that would allow

her to consciously produce these responses were either destroyed or showed

no activity. Because of these results, some physicians argued that Terri could not

choose to perform the behaviors. They said she wasn’t conscious.

Terri’s husband wanted to terminate her life support, but her parents wanted

to continue it. Both sides waged a widely reported legal battle that lasted for

years. A court finally ruled in 2005 that Schiavo’s life support could be termi-

nated. After her death, an autopsy confirmed substantial and irreversible

damage throughout her brain, especially in cortical regions that are important

for consciousness. Many experts now take this report as conclusive evidence

that Terri had no awareness during her coma and was in a persistent vegetative

state, from which there is no recovery (Figure 3.1c).

The question of consciousness clearly is more than an academic issue: It can

be a battleground for life-and-death decisions. Trying to answer the question

of “What is consciousness?” is one of the most fundamental issues in psychol-

ogy. In this chapter, we explore what it means to be conscious and explain how

consciousness depends on brain activity.

3.1  What Does It Mean to Be Conscious? How can someone who is in a coma be conscious? The very possibility seems to contradict our traditional understanding of the term. The cases discussed in the chapter opener, however, highlight two points that are at the core of this chapter: First, people can be conscious of their surroundings even when they do not appear to be. Second, conscious experiences are associated with brain activity. Because

FIGURE 3.1 coma and consciousness (a) Martin Pistorius was believed to be in a coma, but was actually aware of his

surroundings for more than a decade.

(b) Here, Pistorius poses with his wife after recovering. (c) Terri Schiavo spent more than 15 years in a persistent vegetative

state before she was taken off life support.

Her parents and their supporters believed

she showed some awareness. But the dark

areas of the brain scan on the left indicate

that her cortex had deteriorated beyond

recovery. There could not have been activity

in these areas.

(a)

(b)

(c)

WHAT DOES IT MEAN TO BE CONSCIOUS? ■ 79

of the very nature of consciousness, conscious experiences differ from person to person. So to understand the relationship between the brain and consciousness, we need to consider how conscious experiences differ.

Consciousness Is a Subjective Experience consciousness refers to our moment-by-moment subjective experiences. And subjective experiences are personal and unique to whoever is experiencing them, as described in the Learning Tip. Listening to music on your iPod is one example of a subjective experience. Reflecting on the songs you hear and what they mean to you is another. You know you are conscious because you are experiencing the outside world through your senses and because you are aware of what you are thinking. But what gives rise to your consciousness?

Philosophers have long debated the nature of consciousness. As we saw in Chapter 1, in the seventeenth century René Descartes stated that the mind is distinct from the brain. This view is called dualism. Most psychologists reject dualism for materialism, the idea that the brain and the mind are insepara- ble, and that the processing of the brain is what allows the experiences of the mind. According to materialism, the activity of neurons in the brain produces consciousness: the sight of a face, the smell of a rose. More specifically, for each experience—each sight, each smell—there is an associated pattern of brain activ- ity. The activation of this particular group of neurons in the brain gives rise to that particular conscious experience.

The concepts of subjective and objective are important in psychology. It’s easy to understand the difference between them if you remember the information shown in this chart.

LearninG Tip: Understanding Subjectivity

when you see pLease ThinK meaninG

Subjective Information is subject to your own personal view.

Other people will not experience that information in the same way, because it would be subject to their own view.

Objective Information is an object that all people view the same way.

Other people will experience that information in the same way, because it is an object seen in the same way by all.

consciousness The combination of a person’s subjective

experience of the external world and the

person’s mental activity; this combination

results from brain activity.

LearninG GoaLs readinG acTiviTies

a. Remember the key terms about consciousness. List all of the boldface words and write down their definitions.

b. Apply the two levels of consciousness. Provide an example of each level of consciousness from your life.

c. Analyze the impact of unconscious processing. Identify when subliminal messages do versus do not affect thinking and behavior.

d. Apply the global workspace model to your life. Provide examples of how the five regions of your brain process

your awareness of specific information.

e. Understand consciousness in a person with a split

brain.

Describe how a person with a split brain experiences visual

information presented to each hemisphere and whether the

person can or cannot verbally report that information.

Given that processing in the brain underlies consciousness, each of us will experience consciousness personally—that is, subjectively—based on how our own brains process the external world and our internal mental activ- ity. So we cannot know if any two people experience the world in exactly the same way. For example, you think an apple tastes sweet, but your friend finds it sour. Is it possible that you and your friend taste the same flavor but use different labels to describe it? Now say you both call the apple red. Are you definitely seeing the  same color, or might you be seeing different colors but using the same label for your separate experiences?

Even though conscious experiences exist, their subjective nature makes them difficult to study empirically. However, psychology has provided some means to understand conscious experiences. This approach helps all people to view mental processing and behavior in the same way, free from their own personal perspectives.

There Are Different Levels   of Consciousness Remember when you first learned how to drive? You probably paid very close attention to everything you needed to do and where all the stop signs and other cars were. But once you have been driving for several years, it might seem as if you are on autopilot sometimes. You might go down a familiar road, paying no attention to how you drive and what’s around you. Across these two experiences, your quantity, or amount, of consciousness is very different. Describing the levels of consciousness helps us to understand our experiences based on how much attention we pay to external stimuli and internal mental processes at a specific moment. Our levels of consciousness also reveal how aware we are of these experiences.

Our level of consciousness varies continuously throughout the day. When we are fully conscious, we are very alert. We pay attention to information and are acutely aware of our experiences. We notice that we are fully conscious when we are performing difficult or unfamiliar tasks, such as learning to drive. In situations of this kind, we use slow and effortful controlled processes that we need for the task, and we are completely aware while doing so (Figure 3.2).

Now consider a different situation. As you read this chapter, do you always focus intently on the material? Or do you find that sometimes you begin daydream- ing and then realize you have no idea what you just read? In other words, you were going through the motions of reading, but you were mostly unconscious of what you read. In general, all of us can execute routine and well-learned tasks, such as reading, by using automatic processes. These processes are fast and effortless. However, because we are not fully conscious of engaging in such tasks, we won’t remember some of the details of the experiences. Our lack of awareness will prevent the actions from leaving lasting impressions on us. Suppose, for instance, you drive to a familiar destination on autopilot. You probably won’t remember the vehicles you pass or how many traffic lights you stop at.

There is a limit to how many things the mind can be consciously aware of at the same time, however. Even though multitasking is now a way of life, we almost never successfully complete even automatic tasks, such as reading or driv- ing, while doing other things, such as talking on a cell phone or texting. This is a simple psychological fact: We have only so much attention available to consciously

Before reading further, try to remember what you ate for lunch yesterday. If you were able to do this, you just experienced the shift between the two levels of consciousness.

Before reading this, you most likely were not thinking about what you had for lunch yesterday. If that’s true, you were unconscious of this bit of information—that is, you were not aware of it. When you were asked to recall the information, you might have thought for a minute, and then the answer probably popped into your mind. At that point, you were fully conscious of what you ate for lunch. You might even have recalled many details of the experience. This shift is a seemingly simple feat. But behind this shift are all of the intricacies of how the brain helps you direct attention to the information you want or need to be aware of and experience.

has iT happened

To you?

Experiencing the Shift in Levels of Consciousness

FIGURE 3.2 we are Fully conscious when using controlled processes to Learn a complex Task Learning a new and complex task, such

as driving, requires increased effort and

controlled processes. To successfully

perform those processes and master the

task, a person must be fully conscious.

WHAT DOES IT MEAN TO BE CONSCIOUS? ■ 81

experience and respond to information. This is why it is so dangerous to talk on a cell phone or text while driving, as discussed in Chapter 1.

Unconscious Processing Sometimes  Affects Behavior  Have you ever had a slip of the tongue, when you were thinking one thing and said another? Most people have, at some point, made this classic mistake. It is called a Freudian slip—where we express an unconscious thought at an inap- propriate time or in an inappropriate social context. As we try to overcome our blunder, we wonder why it happened.

Considerable evidence indicates that people are affected by thoughts, stimuli, and events they are not aware of (Schooler, Mrazek, Baird, & Winkielman, 2015). subliminal perception refers to times when our sensory systems are processing stimuli but, because the stimuli last only a short time or are subtle, we are generally not aware of them. Over the last several decades, many researchers have explored different ways that unconscious processing during subliminal perception can influence thinking and behavior. For example, in a classic experiment by Nisbett and Wilson (1977), participants were asked to examine pairs of obviously associ- ated words, such as ocean and moon. Then they were asked to view single words, such as detergent, and merely state what other words came to mind. Nisbett and Wilson wanted to find out if viewing the word pairs would influence which words came to mind when participants viewed single words. And if so, would the partici- pants be conscious of this influence?

Indeed, the researchers found that when given the word pair ocean–moon, followed by the word detergent, participants typically said the word tide. Because the moon affects the ocean and the tides, it is not surprising that participants chose the word tide with the word pair. What is surprising is that when the participants were asked why they said “tide,” they usually gave reasons pertaining to the deter- gent’s brand name, such as “My mom used Tide when I was a kid.” This response shows that participants were not aware that the word pair had influenced their thoughts and behavior.

A variety of evidence indicates that much of our everyday behavior occurs without our awareness or intention (Bargh, 2014; Dijksterhuis & Aarts, 2010). This automatic activity seems to happen because we can be influenced by cues from the environment even if we are not aware of them. For example, in one study people were shown pictures of various objects while they were in an fMRI scanner (see Chapter 2). Some of these objects were appetizing pictures of food, although participants did not realize that food cues were relevant. The more activity there was in brain reward regions specifically for the food pictures, the more weight people gained over the next 6 months (Demos, Heatherton, & Kelley, 2012). This brain activity indicates that some people seem to be especially susceptible to processing cues about food, even if they don’t consciously notice it. In turn, this unconscious processing of food cues may be related to their weight gain.

Though material presented subliminally can influence how people process information, it has little or no effect on complex thinking and actions. For example, advertisers have long been accused of using subliminal cues to get people to buy their products (see Try It Yourself ). However, buying a product is a result of many cognitive processes, and the evidence suggests that subliminal messages have quite small effects on purchasing behavior (Greenwald, 1992).

subliminal perception The processing of information by sensory

systems without a person’s conscious

awareness.

Try iT yourseLF: Subliminal Perception

Try to pick out the subliminal

message in this advertisement.

Answer: The ice cubes spell out S-E-X.

82 ■ chapTer 3 CONSCIOUSNESS

scienTiFic ThinKinG: The Relationship Between Consciousness and Brain Activity

Hypothesis: Speci�c patterns of brain activity can predict what a person is seeing.

Research Method:

Participants were shown images with houses superimposed on faces.

Participants were asked to report whether they saw a house or a face.

Researchers used fMRI to measure neural responses in participants’ brains when the participants reported seeing the house or the face.

1

2

3

Results: When participants reported seeing a face, there was greater activity in one temporal lobe region, the fusiform face area. However, when participants reported seeing a house, there was greater activity in different temporal lobe regions, ones associated with object recognition. (For discussions of what information is processed in the brain regions, see Chapter 2.)

Conclusion: Awareness of certain information is associated with activity in the brain region that processes that particular sensory information.

Question: Would it ever be ethical to use brain imaging to uncover what people are thinking if those people haven’t consented? Why or why not?

Brain Activity Gives Rise   to Consciousness Despite what you might see in some movies, scientists cannot—yet—read your intimate thoughts by looking at your brain activity. However, psychology is begin- ning to reveal how brain activity may give rise to specific subjective experiences. For instance, psychologists can identify objects you are seeing by looking at your brain activity (Kay, Naselaris, Prenger, & Gallant, 2008). In one study, research- ers used fMRI to determine, based on the pattern of brain activity at that moment, which picture the participants were seeing: a house, a shoe, a bottle, or a face (O’Toole, Jiang, Abdi, & Haxby, 2005).

Psychologists now examine, even measure, consciousness and other mental states that once were considered too subjective to be studied. For example, Frank Tong and colleagues (Tong, Nakayama, Vaughan, & Kanwisher, 1998) studied the relationship between consciousness and neural responses in the brain. Partici- pants were shown images of houses that were superimposed on faces. When participants reported seeing a face, neural activity increased within the tempo- ral lobe regions associated with face recognition—the fusiform face area. When participants reported seeing a house, neural activity increased within differ- ent temporal lobe regions, ones associated with object recognition. This finding suggests that different types of sensory information are processed by different areas in the brain. Importantly, these specific neural processes are associated with awareness of particular information. You can read more about this study in the Scientific Thinking feature.

WHAT DOES IT MEAN TO BE CONSCIOUS? ■ 83

Temporal lobe:

“I hear things.”

Primary motor cortex:

“I’m all about movement.”

Parietal lobe:

“I’m aware of space.”

Occipital lobe:

“I see things.”

Prefrontal cortex:

“I understand plans.”

FIGURE 3.3 areas of the brain That process awareness of information A central theme in cognitive neuroscience

is that awareness of different aspects of

the world is associated with processing in

different parts of the brain. This simplified

diagram indicates major areas where

processing leads to awareness.

The GLobaL worKspace modeL

The global workspace model is a psycho- logical theory that is based on this brain activity research. The global workspace model proposes that consciousness arises as a function of which brain circuits are active (Baars, 1988; Dehaene, Changeux, Naccache, Sackur, & Sergent, 2006). To put it another way: You experience your brain regions’ activity as conscious awareness of specific information. For instance, when you listen to music, your conscious experience results from activation in particular brain regions. Those regions are processing the sound of the music, the meaning of the lyrics, perhaps your memories of hearing the song in the past, and the emotional states those memories produce. Your total experience results from the simultaneous activity of all the different brain regions supporting these psychological processes.

The key idea of the global workspace model is that no one area of the brain is responsible for general “awareness.” Instead, specific areas of the brain process certain types of information. The processing in these brain areas produces conscious experience of the information (Figure 3.3). From this perspective, conscious- ness is the mechanism that makes us actively aware of information so that we can prioritize what information we need or want to deal with at any moment.

The spLiT brain One way researchers have gained a better understanding of the conscious mind is by studying people who have had brain surgery. For example, in a few rare cases, epilepsy does not respond to modern medications. One strategy is to cut connections within the brain to isolate the site where the seizures begin. After the procedure, a seizure that begins at that site is less likely to spread throughout the cortex.

As you know from Chapter 2, the brain has a right hemisphere and a left hemisphere. The major connection between the hemispheres is the corpus callosum, a massive bundle of neural fibers (Figure 3.4a; see also Figure 2.16). The corpus callosum can be severed without damaging the gray matter (Figure 3.4b), so that the two halves of the brain are almost completely isolated

global workspace model Consciousness is a product of activity in

specific brain regions.

(a) (b)

FIGURE 3.4 split brain (a) This image shows the brain of a person whose corpus callosum is intact.

(b) This image shows the brain of a patient whose corpus callosum has been

removed (as indicated by the red outline).

With the corpus callosum removed, the

two hemispheres of the brain are almost

completely separated.

84 ■ chapTer 3 CONSCIOUSNESS

from each other. The resulting condition, called split brain, has provided many important insights into the basic organization and specialized functions of each brain hemisphere.

What is it like to have your brain split in half ? Perhaps the most striking thing about people whose brains have been divided surgically is that, unlike those who have had other types of brain surgery, they have no immediately apparent prob- lems. In fact, some early investigations suggested the surgery had not affected the patients in any apparent way. They could walk and talk normally, think clearly, and interact socially. There was one important difference, however. In a series of tests on the first people with split brains, Michael Gazzaniga and Roger Sperry (1967) came up with a stunning result: Just as the brain had been split in two, so had the conscious mind! To understand what this finding means, consider how the two halves of the brain usually process information.

The hemispheres normally work together. Images from the visual field’s left  side (left half of what you are looking at) are processed by the right hemi- sphere. Images from the visual field’s right side are processed by the left hemi- sphere (Figure 3.5). The left hemisphere also controls the right hand, and the right hemisphere controls the left hand. In a healthy person, the corpus callo- sum allows the hemispheres to communicate so that the right brain knows what the left is doing and vice versa. By contrast, in split-brain patients, the hemispheres are separated, so this communication cannot take place. The hemispheres work on their own.  This split allows psychologists to separately test the functions of the two hemispheres.

Right hemisphere: better with spatial relationships, processes left visual field information, and controls left side body movements

Left hemisphere: better with language, processes right visual field information, and controls right side body movements

FIGURE 3.5 The brain’s hemispheres work Together Each hemisphere of the

brain processes distinct

information, but the

hemispheres work

together to process all

the information.

split brain A condition in which the corpus callosum

is surgically cut, and the two hemispheres

of the brain do not receive information

directly from each other.

WHAT DOES IT MEAN TO BE CONSCIOUS? ■ 85

As noted in Chapter 2, psychologists have long known that in most people the left hemisphere is most important for language. If a split-brain patient sees two pictures flashed on a screen briefly at the same time—one to the visual field’s right side and one to the left side—the patient will report that only the picture on the right was shown (Figure 3.6a). Why is this? The left hemisphere (or “left brain”), with its control over speech, processes only the picture on the right side. It is the only picture a person with a split brain can talk about.

In many split-brain patients, the right hemisphere has little language ability. The right hemisphere (or “right brain”), having seen the picture on the left, is unable to verbally report what it saw. However, the right brain can act on what it sees: If the picture on the left was of a spoon, the right hemisphere can easily pick out an actual spoon from a selection of objects (Figure 3.6b). It uses the left hand, which is controlled by the right hemisphere.

Normally, the abilities of each hemisphere complement those of the other. For instance, the right brain is generally good at spatial relationships, whereas the left brain is hopeless at them. In one experiment, a participant with a split brain is given a pile of blocks and a drawing of a simple arrangement in which to put them, such as a square. When using the left hand, controlled by the right brain, the participant arranges the blocks effortlessly. But when using the right hand, controlled by the left brain, the participant has a difficult time creating the square. During this dismal performance, the right brain makes the left hand try to slip in and help!

The inTerpreTer This phenomenon reveals an important dimension to the relationship between the brain’s hemispheres: They work together to recon- struct our conscious experiences. Again, this collaboration can be demonstrated in people with split brains. In one experiment, a participant with a split brain—known as J.W.—saw different images flash simultaneously on the left and right sides of a screen (Figure 3.7). Below those images was a stationary row of other images. J.W. was asked to point with each hand to the bottom image most related to the image flashed on that side of the screen above.

(a) When a person with a split brain is asked what he sees, the left hemisphere processes the fork on the right side of the screen and can verbalize that.

(b) The right hemisphere processes the left side of the screen, but cannot verbalize what is seen. However, the person can pick up the correct object using the left hand.

“A fork”

FIGURE 3.6 investigating the hemispheres in the split brain This illustration explains the effects of a

split brain on the hemispheres and on the

person’s responses. (a) Someone with a split brain can name an object only if it

is shown in the right visual field and

processed in the left hemisphere, where

language is produced. (b) The same person can use his left hand to reach for an

object that is shown in the left visual field

and processed in the right hemisphere.

86 ■ chapTer 3 CONSCIOUSNESS

For example, in one trial, a picture of a chicken claw was flashed to J.W.’s left hemisphere, and a snow scene was flashed to his right hemisphere. In response to the image of the claw, J.W.’s right hand (controlled by the left brain) pointed to a picture of a chicken. In response to the snow scene, his left hand (controlled by the right brain) pointed to a picture of a snow shovel. Remember that in people with a split brain, such as J.W., the left hemisphere can verbalize information processed on that side of the brain (e.g., the chicken claw), but it has no access to visual information processed in the right hemisphere (e.g., the snow scene). So, when J.W. was asked why he pointed to those pictures, he used his left brain to reply, “Oh, that’s simple. The chicken claw goes with the chicken, and you need a shovel to clean out the chicken shed.” The left brain could not verbalize the relationship between the shovel and the snow scene, which was processed in the right hemisphere. Instead, it interpreted the left hand’s pointing to the shovel in a way that was consistent with the only knowledge available to the left brain: the chicken claw.

In short, the left hemisphere tends to construct a world that makes sense. The sense-constructing activity in the left hemisphere is called the interpreter. This term means that the left hemisphere is interpreting what the right hemisphere has done (Gazzaniga, 2000). In the last example, the left hemisphere interpreter created a ready way to explain the left hand’s action. The left hemisphere’s expla- nation, however, was unrelated to the right hemisphere’s real reason for command- ing that action. Yet to J.W., the movement seemed perfectly logical once the action had been interpreted.

Experiencing consciousness with a split brain is extremely rare, of course. Nearly all people have two hemispheres that communicate and cooperate on the tasks of daily living and awareness of experiences.

A person with a split brain watches as different images �ash simultaneously on the left and right.

1

Below the screen is a row of other images.

2

The person is asked to point each hand at the bottom image most related to the image �ashed on that side of the screen.

3

The left hemisphere points the right hand at a picture of a chicken head. The left hemisphere says that the chicken claw goes with the chicken head.

4 The right hemisphere points the left hand at a picture of a snow shovel. The left hemisphere decides that the shovel is used to clean up after chickens. (It does not see the snow scene.)

5

FIGURE 3.7 The Left hemisphere interpreter On the basis of limited information, the

left hemisphere interprets behavior that is

processed in the right hemisphere.

HOW DOES SLEEP AFFECT CONSCIOUSNESS? ■ 87

■ Consciousness is how the brain allows us to be aware of and experience the

external world and our internal mental activity.

■ There are two levels of consciousness, which vary in the amount of attention

to and awareness of our experiences.

■ Information that is processed subliminally—that is, without conscious

awareness—can influence basic thinking and behavior for only short periods

of time.

■ Conscious experiences are a result of activity in five specific regions of the

brain that cause us to be aware of specific types of information.

■ People with split brains have a unique experience of consciousness: They are

aware of only information presented to the one hemisphere that processes

that information. And they can verbalize only information processed in the

left hemisphere.

3.1 checKpoinT: What Does It Mean to Be Conscious?

3.2 How Does Sleep Affect Consciousness?

It’s midnight, and you’ve finally gotten into bed. But you’re so nervous about a job interview in the morning that you’re sure you’ll be up all night worrying. The next thing you know, the alarm is going off at 7:00 am. Once again, your brain did that mysterious thing, and you fell asleep. What was your brain doing during those seven hours? Why do we sleep?

People commonly think that the brain shuts itself down during sleep. In fact, many brain regions are more active when we are asleep than when we are awake. And evidence indicates that some complex thinking, such as working on diffi- cult problems, occurs in the brain even when we are sleeping (Walker & Stick- gold, 2006). Given that brain activity is the basis for consciousness, what are our conscious experiences during sleep? Before we answer that question, let’s consider how sleep fits into life.

LearninG GoaLs readinG acTiviTies

a. Remember the key terms about sleep. List all of the boldface words and write down their

definitions.

b. Analyze how brain activity reveals four stages of sleep. Compare brain activity during the four stages of sleep

versus alert wakefulness.

c. Apply the three reasons people need to sleep. Provide, in relation to your own life, three examples of

why you need to sleep.

d. Understand the five common sleep disorders. Describe each sleep disorder using your own words.

88 ■ chapTer 3 CONSCIOUSNESS

FIGURE 3.8 pineal Gland and sleep/wake cycles Changes in light register in the

suprachiasmatic nucleus of the

hypothalamus. The hypothalamus then

signals the pineal gland. The pineal gland

influences the production of melatonin,

which signals the body that it is time to

sleep or wake up.

Pineal glandHypothalamus

Suprachiasmatic nucleus

circadian rhythms The regulation of biological cycles into

regular, daily patterns.

melatonin A hormone, released in the brain, that aids

regulation of circadian rhythms because

bright light reduces production and

darkness increases production.

Sleep Is Part of the Normal   Rhythm of Life  Brain activity and other physiological processes are regulated into daily patterns known as circadian rhythms (circadian roughly translates to “about a day”). Sleep/ wake cycles operate according to circadian rhythms, as do body temperature and hormone levels. Circadian rhythms are influenced by the cycles of light and dark. Even when removed from light cues, however, we (and nonhuman animals as well) continue to show these rhythms.

Multiple brain regions are involved in producing and maintaining circadian rhythms and our sleep/wake cycle. For instance, information about light detected by the eyes is sent to a small region of the hypothalamus called the suprachiasmatic nucleus. This region then sends signals to a tiny structure called the pineal gland (Figure 3.8). The pineal gland influences the release of melatonin, a hormone that travels through the bloodstream and affects various receptors in the body, including some receptors in the brain. Bright light suppresses the production of mela- tonin, whereas darkness triggers its release. It is believed

that melatonin helps regulate the accuracy of our biological clock. Taking melatonin (sold as a dietary supplement) can help people cope with jet lag and shift work, both of which interfere with circadian rhythms. Taking melatonin also appears to help people fall asleep, although it is unclear why this happens.

Individuals differ tremendously in how much they sleep. Infants sleep much of the day. As adults, we spend about one-third of our time sleeping, an average of around 8 hours per night. Some adults report needing 9 or 10 hours of sleep a night to feel rested, whereas others report needing only a few hours. People tend to sleep less as they age. However, researchers were skeptical when a 70- year-old retired nurse, Miss M., reported sleeping only about an hour a night—that is, until she agreed to participate in a study. On her first two nights in a research labora- tory, Miss M. was unable to sleep, apparently because of the excitement. But on her third night, she slept for only 99 minutes, then awoke refreshed, cheerful, and full of energy (Meddis, 1977). You might like the idea of sleeping so little and having all those extra hours of spare time. But bear in mind that most of us do not function well on so little sleep.

Consciousness Changes During Sleep How is being awake different from being asleep? The difference has as much to do with conscious experience as with biological processes. When you sleep, your conscious experience of the outside world is largely turned off. To some extent, however, you remain aware of your surroundings and your brain still processes certain information. Your mind analyzes potential dangers, controls body move- ments, and shifts body parts to maximize comfort. This is why people who sleep next to children or pets tend not to roll over onto them and why, after infancy, most people do not fall out of bed while sleeping.

Before the development of objective methods to assess brain activity, most people believed the brain went to sleep along with the rest of the body. As we discussed in Chapter 2, invention of the electroencephalograph, or EEG, in the 1920s enabled researchers to measure the brain’s electrical activity. When you are awake and fully conscious, you experience many different sources of sensory

HOW DOES SLEEP AFFECT CONSCIOUSNESS? ■ 89

activity. As a result, the neurons in your brain are extremely active. An EEG shows this brain activity as short, frequent, irregular electrical signals called beta waves (shown in Figure 3.9). When you really focus your attention on something, or when you close your eyes and relax, brain activity slows and becomes more regular, producing the electrical pattern known as alpha waves.

Four sTaGes oF sLeep As EEG readings indicate, sleep occurs in stages that are marked by changes in consciousness (see Figure 3.9; also see the Learn- ing Tip on p. 90). When you drift off to sleep, you enter stage 1, shown on the EEG as theta waves. You can easily be aroused from stage 1, and if awakened, you will probably deny that you were sleeping. In this light sleep, you might see fantastical images or geometric shapes. Or you might have the sensation of fall- ing or that your limbs are jerking.

As you progress to stage 2, your breathing becomes more regular, and you become less sensitive to external stimulation. When the EEG shows bursts of brain activity called K-complexes, you are really asleep. Some researchers believe that these bursts are signals from brain mechanisms involved with shut- ting out the external world and keeping people asleep (Steriade, 1992).

The progression to deep sleep occurs through stages 3 and 4, which are seen as one stage because the brain activity is nearly identical (Silber et al., 2007). This period is marked by large, regular delta waves, and it is often referred to as slow-wave sleep. People in slow-wave sleep are very hard to wake and are often disoriented when they do wake up. People still process some information in slow- wave sleep, however, because the mind continues to evaluate the environment for potential danger. For example, parents in slow-wave sleep can be aroused by their children’s cries. Yet they can blissfully sleep through the sounds of sirens or traffic noise, which are louder than the crying children but are not necessarily relevant.

After about 90 minutes of sleep, the sleep cycle reverses, returning to stage 1. At this point, the EEG suddenly shows a flurry of beta wave activity that usually

Alert wakefulness

Beta waves

Beta waves

Alpha waves

Theta waves

Delta waves

K-complex

Just before sleep

Stage 1

Stage 2

Stage 3/4 Slow-wave sleep

REM

FIGURE 3.9 brain activity during sleep These EEG patterns are examples of

electrical brain activity during different

stages of normal sleep.

Have you ever been falling asleep

when suddenly a part of your

body twitched? Or maybe you

were dozing off in class and your

whole body jerked? Either way,

you were most likely aware of

your movement, which is called a

hypnic jerk. Experts don’t know

exactly what causes hypnic jerks,

but many agree that they come

from the muscles’ responding to

brain activity that occurs at the

start of stage 1 sleep. Because

these jerks shift us briefly out

of stage 1 sleep, we become

aware that we just moved. This

conscious awareness usually

does not last long, though. It

fades when we slip back into

sleep for the night, or at least for

the class period.

has iT happened

To you?

The Hypnic Jerk

slow-wave sleep Stages 3 and 4 of deep sleep, when EEGs

reveal large, regular delta waves and

sleepers are hard to awaken.

90 ■ chapTer 3 CONSCIOUSNESS

represents an awake, alert mind. The eyes dart back and forth rapidly beneath closed eyelids. Because of these rapid eye movements, this stage is called rem sleep. It is sometimes called paradoxical sleep because of the paradox of a sleeping body with an active brain. Indeed, some regions of the brain are more active during REM sleep than during wakefulness. But although the brain is active during REM episodes, most of the body’s muscles are paralyzed. At the same time, the body shows signs of genital arousal: Most males of all ages develop erections, and most females of all ages experience clitoral engorgement.

REM sleep is psychologically significant because of its relation to dream- ing. When people are awakened during REM sleep, about 80 percent of the time they report dreaming. By contrast, they report dreaming during non-REM sleep less than half the time (Solms, 2000). What’s more, as you will see later in the chapter, dreams differ in these two types of sleep.

The repeaTinG sLeep cycLe Over the course of a typical night, we cycle through the stages of sleep about five times. As shown in Figure 3.10, we

rem sleep The stage of sleep when EEGs show beta

wave activity associated with an awake,

alert mind, and sleepers experience rapid

eye movements, dreaming, and paralysis of

motor systems.

Consciously awake

Stage 1

Stage 2

Slow- wave sleep

REM

Hours of sleep 876543210

FIGURE 3.10 stages of sleep This chart shows how the four stages of

sleep progress over the course of the night.

An EEG of the brain’s electrical activity can seem like just a bunch of chicken scratches. But to understand how these

waveforms reveal the stages of sleep and consciousness, you need to focus on only two things: the height of the

waveforms (amplitude) and the distance between the peaks (wavelength).

LearninG Tip: Understanding Brain Activity During Sleep

Shorter wavelength (one cycle)

Higher amplitude

Lower amplitude

Baseline

Time

Time

Baseline

Longer wavelength (one cycle)

(b)

(a)(a) EEG waveforms that are shorter in height (lower amplitude) and

have a smaller distance between

the peaks (shorter wavelength)

indicate brain activity that is

associated with awareness of

information. That information can

be in the external world, as in alert

wakefulness. Or it can be in our

own minds when we are dreaming,

as occurs during REM sleep.

(b) By contrast, EEG waveforms that are relatively taller in height

(higher amplitude) and have a

longer distance between the peaks

(longer wavelength) indicate

brain activity that is associated

with deep sleep.

Notice that as we move through the

stages of sleep, EEG waveforms always

increase in height and in the distance

between the peaks. This combined

pattern indicates that we are falling

more deeply asleep.

HOW DOES SLEEP AFFECT CONSCIOUSNESS? ■ 91

progress from stage 1 sleep to slow-wave sleep, then to REM sleep. As morning approaches, the sleep cycle becomes shorter, and we spend relatively more time in REM sleep. You may say you slept like a log all night long, but it’s probably not quite true. People briefly awaken many times during the night, although they do not remember these awakenings in the morning. As people age, they sometimes have more difficulty going back to sleep after awakening.

People Dream While Sleeping dreams are one of life’s great mysteries. Why do our minds conjure up images, fantasies, stories that make little sense, and scenes that ignore physical laws and rules of both time and space? Why does the mind confuse these conjurings with reality? Although they sometimes incorporate external sounds or other sensory experiences that happen while we sleep, dreams are the products of our consciousness. Some people claim they do not dream, or never remember their dreams, but everyone dreams unless a brain injury or medication interferes. In fact, the average person spends 6 years of his or her life dreaming. Yet no one knows if dreaming serves any biological function.

rem dreams and non-rem dreams We dream during both REM and non-REM sleep. But in the two types of sleep, the content of our dreams differs. REM dreams are more likely to be bizarre. They may involve intense emotions, visual and auditory hallucinations ( but rarely taste, smell, or pain), and an uncritical acceptance of illogical events. You fly, are chased by monsters, or tunnel through the center of the Earth. Non-REM dreams feel normal, like every- day life. They may concern ordinary activities such as deciding what clothes to wear or taking notes in class.

The activity of different brain regions during REM and non-REM sleep may be responsible for the different types of dreams and our experiences of them. During non-REM sleep, many brain regions are generally deactivated. In contrast, during REM sleep, some areas of the brain show increased activity, whereas others show decreased activity (Hobson, 2009; Figure 3.11). The content of REM dreams results

FIGURE 3.11 brain activity during rem sleep These two views of the brain show

the regions that are active (red)

and inactive (blue) during REM

sleep. (a) As seen here from the side, the motor cortex, the brain

stem, and visual association areas

are active. So is the amygdala,

which is involved in emotion.

The prefrontal cortex is inactive.

(b) This view from beneath the brain shows other visual

association areas that are active.

This view also reveals the bottom

of the prefrontal cortex, which is

inactive.

Motor cortex

Prefrontal cortex (bottom area)

Amygdala

Visual association areas

(a) (b)

Brain stem

Prefrontal cortex

Visual association areas

Active Inactive

dreams Products of consciousness during sleep

in which a person confuses images and

fantasies with reality.

Try iT yourseLF: Keeping a Dream Journal

Do you want to remember your

dreams better? Just keep a pen

and paper, or your cell phone,

next to your bed so you can

record your dreams as you wake

up. If you wait, you are likely to

forget most of them. Keeping

a dream journal can help you

better understand your dreams

as well your consciousness while

you were dreaming.

92 ■ chapTer 3 CONSCIOUSNESS

from the activation of brain structures associated with motivation, emotion, and reward (e.g., the amygdala). The visual association areas are also activated. At the same time, the prefrontal cortex becomes less activated (Schwartz & Maquet, 2002). As we saw in Chapter 2, the prefrontal cortex is necessary for processing self-awareness, reflective thought, and conscious input from the external world. Because this brain region is less active during REM dreams, the brain’s emotion centers and visual association areas interact without rational thought. The disconnect between feelings and logic contributes to the wilder images in REM dreams.

whaT do dreams mean? Perhaps we should ask, do dreams mean any thing? Sigmund Freud presented one of the first major theories of dreams. According to Freud, dreams contain hidden content that represents unconscious conflicts in the mind of the dreamer. The manifest content is the way visual information is seen (manifested) in the dream and remembered by the dreamer. For example, you might see images in your dream that have you flying through the air, away from dark storm clouds. The latent content is the meaning behind what is being visually manifested. In this example, the meaning behind the visual images in the dream might be that you are trying to get away from a problem with your parents. Some theorists believe that the manifest content disguises the latent content to protect the dreamer from directly confronting a conflict.

Virtually no support exists for Freud’s ideas that dreams represent hidden conflicts and that objects in dreams have special symbolic meanings. Daily life experiences do, however, influence the content of dreams. For example, you may be especially likely to have dreams with anxiety-producing content while studying for exams.

Some dreams have thematic structures, unfolding as events or stories rather than as jumbles of disconnected images. Still, such structures apparently hold no secret meanings. Although your dreams may seem uniquely your own, many common themes occur in dreams. Have you ever dreamed about showing up for an exam and being unprepared or finding that you are taking the wrong test? Many people in college have dreams like these. Even after you finish school and no longer take exams routinely, you probably will have similar dreams about being unpre- pared. Retired professors sometimes dream about being unprepared to teach classes.

acTivaTion-synThesis Theory The sleep researchers John Alan Hobson and Robert McCarley proposed the activation-synthesis theory to explain dreaming (Hobson & McCarley, 1977). According to this theory, neurons in the brain fire randomly during sleep. This random firing can activate parts of the brain that normally process sensory input, such as sights, sounds, and smells. The sleep- ing mind tries to make sense of the resulting sensory activity by combining it with stored memories, and the result is our experience of having a dream. From this perspective, dreams are simply the side effects of mental processes produced by random neural firing.

In 2000, Hobson and his colleagues revised the activation-synthesis theory. They wanted to take into account recent findings in cognitive neuroscience. For instance, they suggested that activation of the limbic regions of the brain (such as the amygdala), which are associated with emotion and motivation, is the source of the emotional content of dreams. They also proposed that the deactiva- tion of the frontal cortices contributes to the delusional and illogical aspects of

activation-synthesis theory Dreams are the result of the brain’s

attempts to make sense of random brain

activity by synthesizing the activity with

stored memories.

HOW DOES SLEEP AFFECT CONSCIOUSNESS? ■ 93

dreams. Critics of Hobson’s theory argue that dreams are rarely as chaotic as we might expect if they were based on random brain activity (Domhoff, 2003). And indeed, most dreams are fairly similar to waking life—they just have some strange features. In sum, psychologists are still not sure what causes us to dream.

Sleep Is an Adaptive Behavior In Chapter 1, we discussed how certain traits are adaptive for a species. That is, each species has traits that help it to survive and reproduce in a changing environ- ment. At first glance, sleep hardly seems adaptive. Tuning out the external world for periods of time can be a threat to survival if a predator pounces or you drive your car into a tree. But we cannot avoid the need to sleep. Eventually our bodies shut down, and we sleep whether we want to or not.

But why do we sleep? Most animals sleep, even if they have peculiar sleeping styles. For instance, in some dolphin species the cerebral hemispheres take turns sleeping. So sleep must serve an important biological purpose. In other words, it must help us adapt and respond in our environment. Researchers have proposed three reasons that sleeping is adaptive and beneficial to us: restoration, preserva- tion, and facilitation of learning.

Three beneFiTs oF sLeep Think about the last time you engaged in demanding physical activity—maybe spending the day helping a friend move or running a long race. Most likely you slept longer than usual afterward. According to the restorative theory, sleep allows the body, including the brain, to rest and repair itself. Growth hormone, released during deep sleep, helps bring about the repair of damaged tissue. Sleep apparently enables the brain to replenish energy stores and also strengthens the immune system (Hobson, 1999).

According to the circadian rhythm theory, sleep has evolved to preserve animals, including humans, from harm. Sleep keeps creatures quiet and inactive when the danger of attack is greatest—usually when it is dark. Each day, animals need only a limited amount of time to accomplish the necessities of survival, such as obtain- ing food. As a result, it is adaptive for animals to spend the rest of the time inactive, preferably hidden. So an animal’s typical amount of sleep depends on how much time that animal needs to obtain food, how easily it can hide, and how vulnerable it is to attack. Small animals tend to sleep a lot. Large animals that are vulnerable to attack, such as cows and deer, sleep little. Large predatory animals, which are generally not vulnerable, sleep a lot (Figure 3.12). We humans depend greatly on vision for survival. We are adapted to sleeping at night because our early ancestors were more at risk in the dark.

Scientists have also proposed that sleep is important because it is involved in strengthening neural connections that serve as the basis of learning. The general idea of this consolidation theory is that circuits wired together during the waking period are consolidated, or strengthened, during sleep (Wilson & McNaughton, 1994). When research participants in one study slept after learning word lists, their recall was better than in control conditions where participants remained awake after learning the lists (Drosopoulos, Schulze, Fischer, & Born, 2007).

Both slow-wave sleep and REM sleep appear to be important for learning to take place, but people may be especially likely to perform better if they dream about the task while sleeping. In one study, participants learned how to run a complex maze. Those who then slept for 90 minutes went on to perform better on the maze than participants who hadn’t slept. Those who dreamed about the maze performed the best of all (Wamsley, Tucker, Payne, Benavides, & Stickgold, 2010).

FIGURE 3.12 sleeping predator After a fresh kill, a lion may sleep for days.

94 ■ chapTer 3 CONSCIOUSNESS

Indeed, there is some evidence that students experience more REM sleep during exam periods, when they might be consolidating a great deal of information (Smith & Lapp, 1991). Changes in sleep patterns over the life cycle also support the argument that sleep, especially REM sleep, promotes the development of brain circuits for learning. Infants and the very young, who learn an enormous amount in a few years, sleep the most and also spend the most time in REM sleep.

sLeep deprivaTion can impair FuncTion We’ve all gone through periods when we didn’t get enough sleep. Does the occasional lack of sleep harm us? Many laboratory studies have examined the effects of temporary sleep depri- vation on physical and cognitive performance. Surprisingly, most studies find that two or three days of sleep deprivation have little effect on strength, athletic abil- ity, or the performance of complex tasks. If you find yourself nodding off over your textbook after a night without sleep, however, you’re not alone (Figure 3.13). When deprived of sleep, people find it difficult to perform quiet tasks, such as reading, and nearly impossible to perform boring or mundane tasks.

By contrast, a long period of sleep deprivation does decrease cognitive perfor- mance. People who suffer from chronic sleep deprivation may experience atten- tion lapses and reduced short-term memory. Studies with rats have found that extended sleep deprivation compromises the immune system and leads to death. Sleep deprivation is also dangerous and potentially disastrous because it makes people prone to microsleeps, in which they fall asleep during the day for a few seconds or even a minute (Coren, 1996).

If your main style of studying is the all-nighter, then findings that link sleep to learning should make you think twice. In one recent study, students who were sleep deprived for just one night showed reduced activity the next day in the hippocampus, a brain area essential for memory (Yoo, Hu, Gujar, Jolesz, & Walker, 2007). These sleep-deprived students also showed poorer memory at later testing. The research- ers found substantial evidence that sleep does more than consolidate memories. Sleep also seems to prepare the brain for its memory needs for the next day.

Sleep deprivation also interferes with the body’s hunger signals, contributing to overeating and weight gain (late-night pizza run, anyone?). It impairs motor abili- ties, contributing to accidents and injuries. Sleep deprivation also increases anxi- ety, depression, and distress. And—to add insult to injury—others perceive us as less attractive when we are sleep deprived, compared with when we are well rested (Axelsson et al., 2010).

When you finally do sleep after a long period of deprivation, you will enter the REM stage more quickly and will have more REM dreams than usual. This REM rebound after deprivation implies that REM sleep is a particularly important part of the sleep process (Suchecki, Tiba, & Machado, 2012).

Sleep Disorders Are Relatively Common  Throughout Life Nearly everyone occasionally has trouble falling asleep or going back to sleep after waking up during the night. When the continual inability to sleep causes signifi- cant problems in daily life, the problem has reached the point of being a sleep disorder.

insomnia It’s 3:00 am, and you’re turning over in bed for what seems like the 500th time. You’re exhausted, but your brain refuses to turn off, and you’re

FIGURE 3.13 sleep deprivation Students may try to avoid sleep.

But sleep will catch up with them!

HOW DOES SLEEP AFFECT CONSCIOUSNESS? ■ 95

beginning to feel desperate. Now and then, each of us has a hard time sleep- ing. If you experience this problem chronically, you might have a sleep disorder. insomnia is a sleep disorder in which a person’s mental health and ability to func- tion are reduced by the chronic inability to sleep. Indeed, insomnia is associ- ated with diminished psychological well-being, including feelings of depression (Bootzin & Epstein, 2011; Hamilton et al., 2007).

Researchers estimate that between 12 percent and 20 percent of adults have insomnia; it is more common in women than in men and in older adults than in younger adults (Espie, 2002; Ram, Seirawan, Kumar, & Clark, 2010). It is hard to estimate how many people truly have insomnia, however. One reason is that many people who believe they are poor sleepers overestimate how long it takes them to fall asleep and often underestimate how much sleep they get in a typical night. Some people even experience pseudoinsomnia, in which they basically dream they are not sleeping. Their EEGs would show they were sleeping. But if you woke them, they would claim they had been awake.

Ironically, a major cause of insomnia is worrying about sleep. When you expe- rience this kind of insomnia, you may be tired enough to sleep. As you try to fall asleep, however, you worry about whether you will get to sleep and may even panic about how a lack of sleep will affect you. This anxiety leads to heightened arousal, which interferes with normal sleep patterns. It’s a vicious cycle.

If you look at the many TV ads and the pharmacy shelves filled with both prescription pills and over-the-counter sleep aids, it would seem that medication is a simple way to deal with insomnia. Sleeping pills may work in the short run, but they can cause significant problems down the road. People may come to depend on the pills to help them sleep. Then if they try to stop taking the pills, they may lie awake wondering whether they can get to sleep on their own. As a better alterna- tive, you might try preventing or even curing insomnia by changing your habits. You can read about some techniques in this chapter’s Using Psychology in Your Life feature, on p. 96.

sLeep apnea Another fairly common sleep disorder is sleep apnea. While asleep, a person with this disorder stops breathing for short periods because his throat closes. In struggling to breathe, the person briefly awakens and gasps for air.

Sleep apnea is most common among middle-aged men and is often associated with obesity, although it is unclear if obesity causes sleep apnea or sleep apnea contributes to obesity (Pack & Pien, 2011; Spurr, Graven, & Gilbert, 2008). Sleep apnea causes people to sleep poorly, feel tired in the daytime, and even have prob- lems such as an inability to concentrate while driving. What’s more, sleep apnea is associated with cardiovascular problems and stroke.

Because they do not remember awakening frequently during the night, people with sleep apnea are typically unaware of their condition. The main symptom that may bring it to their attention is loud snoring that disturbs a partner. For serious cases, physicians often prescribe a device that blows air into the nose or mouth while the person sleeps (Figure 3.14).

narcoLepsy A student who falls asleep during a lecture is likely sleep deprived, but a professor who falls asleep while lecturing is probably experiencing an episode of narcolepsy. In this rare disorder, extreme sleepiness occurs during normal waking hours. During an episode of narcolepsy, a person may experience the muscle paralysis that accompanies REM sleep, perhaps causing her to go limp and collapse. Obviously, people with narcolepsy have to be very careful about the activities they engage in. Unexpectedly falling asleep can be dangerous or fatal,

insomnia A disorder characterized by an inability to

sleep.

sleep apnea A disorder in which a person, while asleep,

stops breathing because the throat

closes; the condition results in frequent

awakenings during the night.

narcolepsy A sleep disorder in which a person

experiences excessive sleepiness during

normal waking hours, sometimes going

limp and collapsing.

FIGURE 3.14 sleep apnea This man has sleep apnea. While he sleeps,

a continuous positive airway pressure

device blows air into his nose or mouth to

keep his throat open.

If you don’t get enough sleep, you are setting yourself up for poor mental

health, poor physical health, and academic difficulties. You probably know

this from personal experience as well as from what you’ve read. But even

though you may have the best intentions, sleep may sometimes play hard

to get. Anxiety, excitement, getting too tired, or having bad sleep habits

may leave you lying in bed, dog-tired but wide awake. Here are some

strategies that can help you develop better sleep:

1. establish a routine to help set your biological clock. Every day, go to bed at the same time and wake up at the same time. Changing the

time you go to bed or wake up each day alters your regular nightly

sleep cycle and can disrupt other physiological systems.

2. avoid alcohol and caffeine in the evening. Alcohol might help you get to sleep more quickly, but it will interfere with your sleep cycle and

most likely make you wake up early the next day. Caffeine is a stimu-

lant, so it will prevent you from falling asleep.

3. exercise regularly. Regular exercise will help maintain your sleep cycle. However, exercising creates arousal that interferes with sleep, so

do not exercise right before going to bed. Instead, do a little stretching

before bedtime to help your mind and body relax.

4. remember, your bed is for sleeping. Most of us do not sleep in our kitchens, nor should we eat in our beds. Or watch TV. Or study. Your

mind needs to associate your bed with sleeping. The best way to make

that association is to use your bed only for sleeping. And maybe a little

cuddling.

5. relax. Do not worry about the future (easier said than done, right?). Write down things to do or worries on a notepad and then put them

aside until the next day. Have a warm bath or listen to soothing music.

Download a couple of meditation and relaxation podcasts, and use the

techniques to help you deal with stress and guide you to restfulness.

6. Get up. When you cannot fall asleep, get up and do something else. Do not lie there trying to force sleep (we all know how well that works, or

rather does not work). If you start feeling sleepy a bit later, go back to

bed and give sleep another chance.

7. Let bygones be bygones. When you have trouble falling asleep on a particular night, do not try to make up for the lost sleep by sleeping

late the next morning or napping during the day. Those zzzz’s are gone.

You want to be sleepy when you go to bed the next night. Sleeping

late, napping, or both will make the next night’s sleep more difficult.

The sleep attitudes and habits you establish during college will be with

you for the rest of your life. Set yourself up for academic success, and for

physical and mental health, by making good sleep a priority and taking

charge of your sleep.

For additional resources, visit the National Sleep Foundation’s Web site at

www.sleepfoundation.org.

an example of what not to do

an example of what to do

usinG psychoLoGy

in your LiFe:

How Can I Develop Better Sleep Habits?

HOW DOES SLEEP AFFECT CONSCIOUSNESS? ■ 97

depending on the situation. Evidence suggests that narcolepsy is a genetic condi- tion that affects transmission of a specific neurotransmitter in the hypothalamus (Chabas, Taheri, Renier, & Mignot, 2003; Nishino, 2007). The most widely used treatments for this condition are drugs that act as stimulants.

rem behavior disorder and sLeepwaLKinG REM behavior disorder is roughly the opposite of narcolepsy. In this condition, the normal paralysis that accompanies REM sleep is disabled. People who experience REM behavior dis order act out their dreams while sleeping. Often, in acting out dreams, they strike their sleeping partners. No treatment exists for this rare sleep dis order. The condition is caused by a neurological deficit and is most often seen in elderly males.

It’s only a month into the first semester, and I already feel behind, James thought. He was excited about starting college, but he hadn’t been quite prepared for the amount

of studying that was required.

James had been especially interested when reading the

section about sleep deprivation in his psychology text-

book. Since starting college, he wasn’t sure he had gotten

more than six hours of sleep in any night. He also was really

surprised to learn that the brain is still so active even during

sleep, especially during REM sleep. No wonder I’m always so tired—my brain never shuts down!

James decided to look online for additional informa-

tion about sleep. At the Huffington Post, his attention was drawn to an interesting headline: “Sounds of Arguing Affect

Babies’ Brains, Even While They’re Asleep.” James read the

article and found out that, as part of a 2013 research study,

20 babies aged 6–12 months slept in an fMRI machine. As

James knew from reading Chapter 2, fMRI measures blood

flow in various areas of the brain. Blood flow indicates how

active a particular region is. While the babies slept, half of

them heard a male voice saying nonsense sentences in an

angry tone of voice. The other half heard the same nonsense

syllables said by the man in a neutral tone of voice. Some of

the babies had parents who verbally fought a lot, whereas

some of the babies had parents who seldom argued. By

using fMRI, the researchers found that in the parts of the

brain responsible for regulating stress and emotion, babies

from high-conflict homes showed greater brain activity in

response to the angry voice than to the neutral voice. That’s sort of sad, James thought, but also kind of cool—more evidence that the brain processes the environment even during sleep.

Intrigued, James looked for other stories covering this

research. At FoxNews.com, he found the same article with a slightly different title: “Sounds of Arguing Affect Sleep-

ing Babies’ Brains.” That seems like a fair headline, too—it just presents the basic facts of the study. But at Telegraph

.co.uk, he found a much more shocking headline: “Arguing Parents Could Damage Their Baby for Life, Study Claims.”

Is that really what they found? Did the other articles I read fail to mention that these infants were followed later in life? James read the Telegraph article more closely. He noticed that although the details of the study were not different,

the journalist seemed to go a step further and speculate on

what the findings of the study might mean even though the

study’s main author was not saying such things.

QuesTions James  noticed  that  the  study  did  not  follow  the  children 

over time. How do you think infants might be affected by 

hearing  arguing  while  sleeping?  How  might  couples  who 

argue a lot differ from those who do not argue? Is it possi-

ble that they differ in how they treat their children? How 

would  such  differences  influence  the  child’s  behaviors, 

including sleep patterns?

beinG a criTicaL consumer:

Is the Sleeping Brain Ever Really Asleep?

98 ■ chapTer 3 CONSCIOUSNESS

We can describe consciousness by noting the level, or amount, of consciousness that we have at any one moment. But we can also describe a state of consciousness. This state is not determined by the level of consciousness—by whether a person is conscious or unconscious. It is determined by the quality of consciousness. In other words, how clearly do we experience the external world? How clearly do we experience the internal world, and how organized are our thoughts? An altered state of consciousness occurs when the external world seems much more or less clear to us than usual, and when our thoughts are much more or less organized than usual.

3.3 What Is an Altered State of Consciousness?

LearninG GoaLs readinG acTiviTies

a. Remember the key terms about altered states of

consciousness.

List all of the boldface words and write down their

definitions.

b. Apply altered states of consciousness to your life. Provide two examples of variations in the quality, or clarity,

of your conscious experiences.

c. Understand how hypnosis affects consciousness. Summarize the two theories of how hypnosis may, or may

not, alter awareness.

d. Understand how meditation and flow may alter

consciousness.

Describe in your own words the ways that meditation and

flow affect awareness.

■ We experience changes in consciousness when we sleep as we become less

aware of the external world, yet we are still able to respond when necessary.

■ Sleep has four stages. Each stage is characterized by brain activity that is the

basis for how we experience that stage of sleep.

■ We dream differently during REM sleep than during non-REM sleep.

■ Three theories have been proposed to explain why sleeping is beneficial.

■ Five disorders affect the experience of sleeping.

3.2 checKpoinT: How Does Sleep Affect Consciousness?

By contrast, sleepwalking is most common among young children. Techni- cally called somnambulism, this relatively common behavior occurs during slow-wave sleep, typically within the first hour or two after falling asleep. During an episode, the person is glassy-eyed and seems disconnected from other people and/or the surroundings. Contrary to popular belief, no harm is done if the sleepwalker is awakened during the episode. Being gently walked back to bed is safer for the sleepwalker than being left to wander around and potentially get hurt.

WHAT IS AN ALTERED STATE OF CONSCIOUSNESS? ■ 99

FIGURE 3.15 in a coma but conscious The brain images on the top are from the

patient, a young woman in a coma who

showed no visible signs of conscious

awareness. The images on the bottom are

a composite from the control group, which

consisted of healthy volunteers. Both the

patient and the control group were told

to visualize playing tennis and walking

around. Right after the directions were

given, the neural activity in the patient’s

brain appeared similar to the neural

activity in the control group’s brains.

Similar regions of the brain were activated in the coma patient …

… and in healthy volunteers, when patient and volunteers visualized the same activities.

Tennis Imagery

Patient

Controls

Spatial Navigation Imagery

There Are Different Altered States   of Consciousness When you hear the phrase altered consciousness, your first thought might be of intense meditation, drug-induced hallucinations, or something out of zombie movies. And it is true that a person’s state of consciousness, or quality of aware- ness, can be altered in extreme ways. Indeed, the opener for this chapter describes two people who were in comas. Martin Pistorius was actually mentally alert. Terri Schiavo was not.

From the outside, Pistorius and Schiavo seemed to act the same, as both were in apparent comas. So behavior could not tell us about their experiences. However, brain imaging may be useful for identifying the extent of a patient’s brain injury and likelihood of recovery, and it may provide insight into the person’s conscious- ness during the coma. For example, one 23-year-old woman who was in a coma could not give any outward signs of aware- ness. But researchers wondered whether she was able to understand language and respond to the experimenters’ requests. When she was asked to imagine play- ing tennis or walking through her house (Owen et al., 2006), the woman’s pattern of brain activity became quite similar to the patterns of control participants who also imagined playing tennis or walking through a house (Figure 3.15).

We have just been looking at cases of extremely altered states. Less dramatic changes occur in consciousness natu- rally over the course of the day. These natural changes are often caused by what is happening in the environment or what we are doing. For instance, learning to play a piece on the piano might produce intense concentration. By contrast, watching television might lead to “zoning out,” with little awareness beyond what is on the screen. This section considers three ways a person can purposely reach an altered state of consciousness: hypnosis, meditation, and immersion in an action.

Hypnosis Can Produce Changes in  Perception, Memory, and Action In June 2012, Maxime Nadeau, a young hypnotist-in-training, hypnotized a group of 13- and 14-year-old girls during a performance at a school in Quebec, Canada. But things didn’t go exactly as planned: Nadeau was unable to bring several of the girls out of hypnosis. He had to call on his mentor, Richard Whitbread, to break the spell. Whitbread did so and later told the Canadian Broadcasting Company: “There were a couple of students who had their heads lying on the table, and there were [others] who, you could tell, were in trance. . . . The eyes were open and there was nobody home.” What does it mean that “nobody was home”? Were the girls really in a trance? Can a hypnotist produce a real change in mental state, or is hypnosis just good theater? What exactly is hypnosis?

100 ■ chapTer 3 CONSCIOUSNESS

posThypnoTic suGGesTion In hypnosis, a person, responding to sugges- tions, experiences changes in memory, perception, and/or voluntary action (Kihl- strom, 1985; Kihlstrom & Eich, 1994). Psychologists generally agree that hypnosis affects some people, but they do not agree on whether hypnotists can produce a genuinely altered state of consciousness (Jamieson, 2007).

A hypnotist may work with one or more people at a time. To begin the hypnosis, the hypnotist makes a series of suggestions such as, “You are becoming sleepy. . . . Your eyelids are drooping. . . . Your arms and legs feel very heavy.” As the listener falls more deeply into the hypnotic state, the hypnotist makes more suggestions. “You cannot move your right arm,” “You feel warm,” and so on. If everything goes according to plan, the listener follows all the suggestions as though they are true (Figure 3.16).

Sometimes the hypnotist suggests that, after the hypnosis session, the listener will experience some change. Such a posthypnotic suggestion is usually accompa- nied by the instruction to not remember the suggestion. For example, a hypnotist might suggest, “When I say the word dog, you will stand up and bark like a dog. You will not remember this suggestion.” And, much to the delight of the audience, later on the person stands up and barks like a dog.

Therapists sometimes hypnotize patients and give them posthypnotic suggestions to help them lose weight or quit smoking. But evidence suggests that hypnosis has quite modest effects on these behaviors. There is clear evidence, however, that some posthypnotic suggestions can at least subtly influence behaviors.

Consider a study of moral judgment conducted by Thalia Wheatley and Jonathan Haidt (2005). Participants received a posthypnotic suggestion to feel a pang of disgust whenever they read a neutral, or non-offensive, word (e.g., the word often). After receiving this suggestion, participants made more-severe moral judgments when reading stories that included the word often, even when the stories were not immoral. Like people in split-brain studies, the participants were surprised by their reactions and sometimes made up justifications for their harsh ratings, such as saying that the lead character seemed “up to something.” This result suggests that the left hemisphere interpreter might be involved in people’s understanding their own behavior when that behavior results from posthypnotic suggestion or other unconscious influences.

To the extent that hypnosis works, it relies more on the person being hypnotized than on the skill of the hypnotist. Indeed, tests for hypnotic suggestibility show that hypnosis works primarily for people who are highly suggestible (Kallio & Revonsuo, 2003). Researchers cannot precisely identify the personality character- istics of people who can or cannot be hypnotized, but suggestibility is related to getting absorbed in activities easily, not being distracted easily, and having a rich imagination (Balthazard & Woody, 1992; Crawford, Corby, & Kopell, 1996; Silva & Kirsch, 1992). Furthermore, a person who dislikes the idea of being hypnotized or finds it frightening would probably not be hypnotized easily. To be hypnotized, a person must go along with the hypnotist’s suggestions willingly. There is no reli- able evidence that people will do things under hypnosis that they would normally object to.

Two Theories oF hypnosis Some psychologists believe that a person under hypnosis essentially plays the role of a hypnotized person. The person is not faking, but acts the part as if in a play, willing to perform actions called for by the “director,” the hypnotist. According to this sociocognitive theory of hypnosis, hypnotized people behave as they expect hypnotized people to behave, even if those expectations are faulty (Kirsch & Lynn, 1995; Spanos & Coe, 1992).

FIGURE 3.16 hypnotized? Are hypnotized people in an altered state

of consciousness, or are they just playing a

part suggested to them by the hypnotist?

hypnosis A social interaction during which a person,

responding to suggestions, experiences

changes in memory, perception, and/or

voluntary action.

sociocognitive theory of hypnosis Hypnotized people are not in an altered

state, but they behave in a way that is

expected in that situation.

WHAT IS AN ALTERED STATE OF CONSCIOUSNESS? ■ 101

An alternative theory, the dissociation theory of hypnosis, acknowledges the importance of social context, but views hypnosis as a truly altered state. Accord- ing to this theory, hypnosis is a trancelike state in which conscious awareness is separated, or dissociated, from other aspects of consciousness (Gruzelier, 2000). In support of this theory, many brain imaging studies have found alterations in the brain activity of a hypnotized person (Rainville, Hofbauer, Bushnell, Duncan, & Price, 2002). In one of the earliest such studies, Stephen Kosslyn and colleagues (2000) demonstrated that when hypnotized participants were asked to imagine black-and-white objects as having color, they showed activity in visual cortex regions involved in color perception. Hypnotized participants asked to drain color from colored images showed diminished activity in those same brain regions. This activity pattern did not occur when participants were not hypnotized. These results indicate that hypnotic suggestion may indeed change brain function. And if brain function is changed during hypnosis, then maybe hypnosis really does alter consciousness. After all, it seems unlikely that a person could alter his brain activ- ity to please a hypnotist, even if that hypnotist is a psychological researcher.

hypnosis For pain One of the best supported uses of hypnosis is hypnotic analgesia, a form of pain reduction. Laboratory research has demonstrated that this technique works reliably (Hilgard & Hilgard, 1975; Nash & Barnier, 2008). For instance, a woman who plunges her arm into extremely cold water will feel great pain, and the pain will intensify over time. On average, a person can keep the arm in the water for only about 30 seconds, but a person experiencing hypnotic analge- sia can hold out longer. As you might expect, people high in suggestibility who expe- rience hypnotic analgesia can tolerate the cold water the longest (Montgomery, DuHamel, & Redd, 2000).

There is considerable evidence from clinical settings that hypnosis is effective in dealing with acute pain (e.g., during surgery and dental work) and chronic pain (e.g., from arthritis, cancer, or diabetes; Patterson & Jensen, 2003). A patient can also be taught self-hypnosis to improve recovery from surgery.

Hypnotic analgesia may work by changing the patient’s interpretation of pain rather than by diminishing pain. That is, the patient feels the sensations associ- ated with pain, but feels detached from those sensations (Price, Harkins, & Baker, 1987). An imaging study confirmed this pattern by showing that although hypnosis does not affect the sensory processing of pain, it reduces brain activity in regions that process the emotional aspects of pain (Rainville, Duncan, Price, Carrier, & Bushnell, 1997).

Findings such as these provide considerable support for the dissociation theory of hypnosis. It seems unlikely that either expectations about hypnosis or social pressure to not feel pain could explain how people experiencing hypnotic analgesia are able to undergo painful surgery and not feel it. Nor is it likely that expectations or social pres- sure could result in the altered brain activity seen during hypnotic analgesia.

Meditation Affects Cognitive Processing  and Brain Function With a growing awareness of different cultural and religious practices and alternative approaches to medicine, people in the West have become more interested in examining Eastern techniques of altering consciousness, includ- ing meditation. Different forms of meditation are central to many Eastern reli- gions, including Hinduism, Buddhism, and Sikhism. But the common thread among all of these religions is that through intense contemplation, the meditator

dissociation theory of hypnosis Hypnotized people are in an altered state

where their awareness is separated from

other aspects of consciousness.

meditation A practice in which intense contemplation

leads to a deep sense of calmness that

has been described as an altered state of

consciousness.

102 ■ chapTer 3 CONSCIOUSNESS

develops a deep sense of tranquility that has been described as an altered state of consciousness.

There are two basic forms of meditation. In concentrative meditation, you focus your attention on one thing, such as your breathing pattern, a mental image, or a specific phrase (sometimes called a mantra). In mindfulness meditation, you let your thoughts flow freely, paying attention to them but not examining their mean- ing or reacting to them in any way. As Try It Yourself suggests, why not take a break from reading and try one of these methods for at least 20 minutes?

Religious forms of meditation are meant to bring spiritual enlightenment. Most forms of meditation popular in the West are not necessarily religious. They are meant primarily to expand the mind, bring about feelings of inner peace, and help people deal with the tensions and stresses in their lives.

The meditation practice perhaps best known in the West is transcendental meditation (TM). This form involves meditating with great concentration for 20 minutes twice a day. In a 2006 study, a large number of heart patients were randomly assigned to TM or an educational program. After 16 weeks, the patients practicing TM improved more than the control group on a number of health measures, such as blood pressure, blood lipids, and insulin resistance (Paul- Labrador et al., 2006). Unfortunately, this study does not show which aspects of TM produced the health benefits. Was it simply relaxing, or was it an altered state of consciousness?

Psychologists also study how meditation affects cognitive processing and brain function (Cahn & Polich, 2006). One such study found that subjects who completed meditation training showed greater stress reduction and more signif- icant improvement in attention than a group that received simple relaxation training (Tang et al., 2007).

Some researchers argue that long-term meditation brings about structural changes in the brain that help maintain brain function over the life span. For instance, although the volume of gray matter typically diminishes with age, one study found that this volume did not diminish in older adults who practiced Zen meditation (Pagnoni & Cekic, 2007). This finding suggests that Zen meditation might help preserve cognitive functioning as people age. However, remember from Chapter 1 that correlation does not prove causation. People who meditate may differ substantially from people who do not, especially regarding lifestyle choices such as diet and taking care of their health. Careful empirical research should contribute significantly to our understanding of meditation’s effects.

Flow Activities Can Lead to Altered  Consciousness Hypnosis and meditation are activities specifically intended to alter a person’s state of consciousness. But participation in an intense sport or an intense religious ceremony can also lead to altered consciousness.

Here’s a situation you’ve likely heard about or even experienced yourself: A marathon runner goes from feeling pain and fatigue to being euphoric and feeling a glorious release of energy. Commonly known as runner’s high, this state is partially mediated by physiological processes (especially endorphin release; see Chapter 2). It also occurs due to a shift in the state of consciousness. Religious ceremonies can create similar alterations of consciousness. Indeed, such rituals often involve chanting, dancing, or other behaviors as a way for people to lose themselves in reli- gious ecstasy. Like meditation, religious ecstasy directs attention away from the self and allows the practitioners to focus on their spiritual awareness (Figure 3.17).

FIGURE 3.17 religious ecstasy This woman appears to be overcome

with religious ecstasy during a ceremony

in an African-Christian church in Nigeria.

In such cases, people experience altered

consciousness when their attention is

directed away from themselves and onto

spiritual awareness.

Try iT yourseLF: Meditation

To practice concentrative

meditation, focus your attention

on your breathing pattern, in and

out. To practice mindfulness

meditation, let your thoughts

flow freely without reacting to

them.

WHAT IS AN ALTERED STATE OF CONSCIOUSNESS? ■ 103

One psychological theory about such peak experiences is based on the concept of flow, “a particular kind of experience that is so engrossing and enjoyable [that it is] worth doing for its own sake even though it may have no consequence outside itself ” (Csikszentmihalyi, 1999, p. 824). Flow is a state of altered consciousness in that you lose track of time, forget about your problems, and fail to notice other things going on (Csikszentmihalyi, 1990). Flow experiences have been reported during many activities, including playing music (O’Neil, 1999) or a moderately challenging version of the computer game Tetris (Keller & Bless, 2008), participating in sports (Jackson, Thomas, Marsh, & Smethurst, 2001), and simply doing satisfying jobs (Demerouti, 2006). In the view of the psychologist Mihaly Csikszentmihalyi (1999), flow experiences bring personal fulfillment and make life worth living.

escapinG The seLF Our conscious thoughts can be dominated by worries, frustrations, and feelings of personal failure. Sometimes people get tired of dealing with life’s problems and try to make themselves feel better through escapist pursuits. Potential flow activities such as sports or work may help people escape thinking about their problems, but people engage in such activities mainly to feel fulfilled. The difference is between escaping and engaging. Sometimes people choose to escape the self rather than engage with life: To forget their troubles, they drink alcohol, take drugs, play video games, watch television, surf the Web, text, and so on. The selective appeal of escapist entertainment is that it distracts people from reflecting on their problems or their failures, thereby helping them avoid feeling bad about themselves.

Some escapist activities—such as running or reading—tend to have posi- tive effects, some tend to be relatively harmless distractions, and some tend to come at great personal expense. For example, people obsessively playing online games such as World of Warcraft have lost their jobs and even their marriages (Figure 3.18). They have even taken the lives of their offspring: In South Korea in 2010, Kim Jae-beom and his common-law wife, Kim Yun-jeong, neglected their 3-month-old daughter to the point that she died of starvation. The couple report- edly spent every night raising a virtual daughter as part of a role-playing game they engaged in at an Internet café. Some ways of escaping the self can also be associated with self-destructive behaviors, such as binge eating, unsafe sex, and, at the extreme, suicide. According to the social psychologist Roy Baumeister (1991), people engage in such behaviors because they want to escape their problems by reducing self- awareness. The state of being in lowered self-awareness may reduce long-term planning, reduce meaningful thinking, and help bring about uninhibited actions. The next section of this chapter looks at a common way people try to escape their problems—namely, using drugs or alcohol to physiologically alter consciousness.

flow A highly focused, altered state of

consciousness, when awareness of self and

time diminishes due to being completely

engrossed in an enjoyable activity.

FIGURE 3.18 escapist entertainment Simple entertainment can shift toward

obsession when a person continually tries

to escape from his problems.

■ Normally, our state of consciousness allows us to experience the external

world and our thoughts clearly. Altered consciousness makes the outer world

more or less vivid and our thoughts more or less organized.

■ Patterns of brain activity suggest that people who have been hypnotized

experience a shift in consciousness and are not simply faking it.

■ Altered states of consciousness may be achieved through three forms of

meditation.

■ In cases of extreme physical exertion or profound religious experiences,

people can experience a type of altered consciousness called a flow state.

3.3 checKpoinT: What Is an Altered State of Consciousness?

104 ■ chapTer 3 CONSCIOUSNESS

3.4 How Do Drugs Alter Consciousness?

Throughout history and across all cultures, people have discovered that ingest- ing certain substances can alter their mental states. Some of those altered states can be similar to the flow experience we described earlier. Others can be very pleasant for a brief period. However, some of those mental states, especially over the long term, can have negative consequences, including injury or death. According to the United Nations Office on Drugs and Crime (2009), upward of 250 million people around the globe use illicit drugs each year. This section looks at the effects of drug use from the perspective of psychology.

People Use—and Abuse—Many  Psychoactive Drugs Drugs are a mixed blessing. If they are the right ones, taken under the right circum- stances, they can provide relief from severe pain or a moderate headache. They can help people suffering from depression lead more satisfying lives. But many of these same drugs can be used for “recreational” purposes: to alter physical sensa- tions, consciousness, thoughts, moods, and behaviors in ways that users believe are desirable. This recreational use can sometimes have negative consequences.

Psychoactive drugs are mind-altering substances that change the brain’s neurochemistry by activating neurotransmitter systems. The effects of a particu- lar drug depend on which neurotransmitter systems it activates. Drugs also differ in the effects they have on the user. stimulants are drugs that increase behavior and mental activity. By contrast, depressants decrease behavior and mental activity. opiates are useful for reducing pain, but also provide intense feelings of pleasure. hallucinogenics are drugs that change the subjective experiences of perception, thought, and emotion. This section considers a few common psycho- active drugs. Some of these drugs have legitimate medical uses, but all of them are commonly abused outside of treatment.

sTimuLanTs Stimulants activate the sympathetic nervous system, increasing heart rate and blood pressure. They improve mood, but they also make people become restless, and they disrupt sleep. Many substances act as stimulants, even though the effects are often mild. For instance, coffee, soda, and energy drinks often contain moderate doses of the stimulant caffeine, but those doses can add up if someone

stimulants Psychoactive drugs that increase both

mental processes and physical activity.

depressants Psychoactive drugs that decrease both

mental processes and physical activity.

opiates Psychoactive drugs that reduce pain and

produce pleasurable feelings.

hallucinogenics Psychoactive drugs that affect perceptual

experiences and evoke sensory images

even without sensory input.

LearninG GoaLs readinG acTiviTies

a. Remember the key terms about drugs. List all of the boldface words and write down their

definitions.

b. Apply the effects of the four classes of psychoactive

drugs.

Provide four fictional cases that describe what people

experience when using each of these classes of drugs.

c. Understand how each drug within the four classes alters

peoples’ state of consciousness.

Summarize in your own words the effects of one example

of a specific drug from each of these four classes.

d. Analyze the two aspects of addiction: tolerance and

withdrawal.

Differentiate between tolerance and withdrawal in terms of

physical and psychological aspects of addiction.

HOW DO DRUGS ALTER CONSCIOUSNESS? ■ 105

FIGURE 3.19 early coke ad This advertisement’s claim that Coca-Cola

is “a valuable Brain Tonic” may have been

made because the company included

cocaine in the drink before 1906.

FIGURE 3.20 methamphetamine’s effects on the brain This image is a combination of the

brain scans from 29 methamphetamine

addicts. The red and yellow areas

represent the brain damage that typically

occurs in the frontal cortex because of

methamphetamine abuse (Kim et al.,

2006). Such damage may explain the

cognitive problems that occur with

methamphetamine use.

has several drinks in a day. Drinking these beverages at night commonly interferes with sleep. Chocolate contains a chemical similar to caffeine that produces stimulating effects. The drug nicotine, found in ciga- rettes (and e-cigarettes) is also a stimulant. More-powerful stimulants include cocaine and amphetamines. Amphetamines are found in some drugs used to treat attention-deficit/hyperactivity disorder (ADHD), as you will learn in Chapter 15. Students sometimes take amphetamines, such as Adderall, to help them study. The majority of college students report knowing someone who has used a nonprescribed stimulant as a study aid (Weyandt et al., 2013).

Stimulants work by allowing the neurotransmitter dopamine (see Chapter 2) to remain in the synapse between neurons longer, which prolongs the impact of dopamine. However, sometimes stimulants also increase the release of dopamine by neurons (Fibiger, 1993). Dopamine seems to be involved in drug use in two ways. First, the increased dopamine is associated with greater reward, or increased liking ( Volkow, Wang, & Baler, 2011). Second, the increased dopa- mine leads to a greater desire to take a drug, even if that drug does not produce pleasure. Thus sometimes an addict wants a drug even if she does not like the effects of the drug (Kringelbach & Berridge, 2009). Available evidence suggests that dopamine is particularly important for the wanting aspect of addiction.

Cocaine is a stimulant derived from the leaves of the coca bush, which grows primarily in South America. Cocaine has a long history of legal use in America. John Pemberton, a pharmacist from Georgia, was impressed with cocaine’s effects. In 1886, he added the drug to soda water for easy ingestion, creating Coca-Cola (Figure 3.19). In 1906, the U.S. government outlawed cocaine, so it was removed from the drink. To this day, coca leaves are still used in the making of Coke, but the active ingredient has been removed. Illegal use of cocaine occurs when the drug is inhaled (snorted) as a powder or smoked in the form of crack cocaine. Users experience a wave of confidence and feel good, alert, energetic, sociable, and wide awake. Cocaine produces its stimulating effects by increasing the concentration of dopamine in the neural synapse. These short-term effects are especially intense for crack cocaine users. But habitual use of cocaine in large quantities can lead to paranoia, psychotic behavior, and violence (Ottieger, Tressel, Inciardi, & Rosales, 1992).

Methamphetamine (meth) is also a stimulant, as it breaks down into amphetamine in the body. Meth is the world’s second most commonly used illicit drug, after marijuana (Barr et al., 2014). However, the use of meth may be declining (Gonzales, Mooney, & Rawson, 2010). This drug was first developed in the early twentieth century as a nasal decongestant, but its recreational use became popular in the 1980s. The National Insti- tute of Drug Abuse (2014) estimates that around 4 percent of the U.S. population has tried meth amphetamine. One factor that has encouraged use of this drug and may explain its popularity is how easy it is to make using common over-the- counter drugs and simple lab methods. By blocking the reuptake of dopamine and increasing its release, methamphetamine yields much higher levels of dopamine in the synapse. Methamphetamine stays in the body and brain much longer than, say, cocaine, so its effects are prolonged. Over time, methamphetamine damages various brain structures, including the frontal lobes (Figure 3.20). The drug ’s effects on the temporal lobes and the limbic system may explain the harm done

106 ■ chapTer 3 CONSCIOUSNESS

to memory and emotion in long-term users (Kim et al., 2006; Thompson et  al., 2004). Methamphetamine also causes considerable damage to the rest of the body (Figure 3.21).

druGs wiTh haLLucinoGenic eFFecTs Several drugs have hallucino- genic effects that alter sensation and perception. These drugs change how users experience the world around them. One well-known hallucinogen is lysergic acid diethylamide (LSD). LSD was discovered in 1938 and is made from a chemi- cal found in certain types of fungus, called ergot, that grow on rye and other wheats. It is usually taken orally, and the drug experience, informally referred to as a “trip,” lasts for about 12 hours. LSD changes sensory experiences and can produce extreme hallucinations, pleasurable or unpleasurable. People using LSD have a distorted sense of time. Many other substances, such as certain plants and fungi, have psychedelic properties. For example, eating the top part of the peyote cactus or certain types of mushrooms, such as psilocybin mushrooms, produces hallucinogenic effects. These psychedelic substances have been used in various religious rites throughout history.

The most commonly used drugs with hallucinogenic effects are MDMA and marijuana. MDMA produces an energizing effect similar to that of stimulants, but it also causes slight hallucinations. The street version of MDMA is sold as pills named ecstasy or Molly, but these pills often contain other chemicals in addi- tion to MDMA. The drug first became popular in the 1990s among young adults in nightclubs and at all-night parties known as raves. According to the National Institute of Drug Abuse (2014), ecstasy use by high school students increased from 3.7 percent to 4.7 percent between 2009 and 2010.

Compared with amphetamines, MDMA is associated with less dopamine activity and more serotonin activity. The serotonin release may explain ecstasy’s hallucinogenic properties. Research on animals has shown that MDMA can cause damage to a number of brain regions, particularly the prefrontal cortex and the hippocampus (Halpin, Collins, & Yamamoto, 2014). Studies with humans show evidence of a range of impairments from long-term ecstasy use, especially memory problems and a diminished ability to perform complex tasks (Parrott, 2013). Of course, any drug can be toxic in large doses or when taken for long periods.

FIGURE 3.21 methamphetamine’s effects on the person These before-and-after photos

dramatically illustrate physical damage

from methamphetamine. When the photo

on the left was taken, Theresa Baxter was

42 and not a methamphetamine addict.

The photo on the right was taken less than

3 years later, after Baxter was arrested

for crimes she committed to support her

addiction.

HOW DO DRUGS ALTER CONSCIOUSNESS? ■ 107

FIGURE 3.22 death from mdma Brandy French was 16 years old when she died of an overdose of esctasy at a rock concert. Here,

Brandy’s father and aunt are shown visiting her grave, in Pittsburgh.

Currently, controversy exists over whether occasional recreational use of ecstasy by itself causes long-term damage. Some ecstasy users take very high doses or regu- larly use other drugs, such as methamphetamine, that are known to be neurotoxic (Gallagher et al., 2014). Growing evidence suggests that MDMA may have poten- tial benefits for use in the treatment of posttraumatic stress disorder (Doblin et al., 2014; you will learn more about this disorder in Chapter  14). The drug promotes feelings of compassion and trust and reduces the negative emotions that people have about their traumatic experiences even after the drug wears off (Mithoefer et al., 2013). When used as part of treatment, MDMA does not have negative effects on health or cognition (White, 2014).

One concern is that many pills being sold as ecstasy or Molly contain other dangerous chemicals, such as drugs used to anaesthetize animals. Even when they contain MDMA, the doses vary widely, increasing the likelihood of overdose (Morefield, Keane, Felgate, White, & Irvine, 2011; Wood, Stribley, Dargan, Davis, Holt, & Ramsey, 2011). Since the early 2000s, many concertgoers have died after consuming what they believed to be ecstasy or Molly (Figure 3.22).

Marijuana consists of the dried leaves and flower buds of one type of cannabis plant. This is the most widely used illicit drug in the world. Many drugs can easily be categorized as a stimulant, a depressant, or a hallucinogen, but marijuana has the effects of all three classes of drugs. The psychoactive ingredient in marijuana is THC, or tetrahydrocannabinol. This chemical produces a relaxed mental state, an uplifted or contented mood, and some perceptual and cognitive distortions. Marijuana users report that THC makes perceptions more vivid, and some say it especially affects taste. However, most first-time marijuana users do not experi- ence the “high” obtained by more experienced users. Novice smokers might use inefficient techniques, they might have trouble inhaling, or both. Users apparently must learn how to appreciate the drug ’s effects (Kuhn, Swartzwelder, & Wilson, 2003). In this way, marijuana differs from most other drugs. Generally, the first time someone uses a drug other than marijuana, the effects are very strong, and subsequent uses lead to tolerance, in which a person has to use more of the drug to get the same effect.

108 ■ chapTer 3 CONSCIOUSNESS

Marijuana is also used for its medicinal properties. For instance, cancer patients undergoing chemotherapy report that marijuana is effective for over coming nausea. Nearly 1 in 4 AIDS patients reports using marijuana to relieve nausea and pain (Prentiss, Power, Balmas, Tzuang, & Israelski, 2004). The medical use of marijuana is legal in many countries and Ameri- can states. Nevertheless, this practice is controversial due to the possibil- ity that chronic use can cause health problems or lead to abuse of the drug. Some countries and American states have concluded that such risks are offset by a reduction in the problems created by criminal activity associ- ated with illegal drug use. Recently, the states of Colorado and Washing- ton legalized recreational marijuana use by adults. Many other states are expected to follow suit.

opiaTes Opiates include heroin, morphine, and codeine. These drugs provide enormous reward value, producing feelings of relaxation, insen- sitivity to pain, and euphoria. Heroin provides a rush of intense pleasure that most addicts describe as similar to orgasm. The rush evolves into a pleasant, relaxed stupor. Heroin and morphine are highly addictive, perhaps because they have dual physical effects: They increase pleasure by binding with opiate receptors and increase wanting of the drug by activating dopamine receptors (Kuhn et al., 2003).

Opiates have been used to relieve pain for hundreds of years. Indeed, before the twentieth century, heroin was widely available without a prescription and was marketed by Bayer, the aspirin company (Figure 3.23). The benefits of short-term opiate use to relieve severe pain seem clear. But long-term opiate use to relieve chronic pain is much more likely to lead to abuse or addiction than is short-term use (Ballantyne & LaForge, 2007). Moreover, long-term use of opiates is associ- ated with a number of neurological and cognitive deficits, such as attention and memory problems (Gruber, Silveri, & Yurgelun-Todd, 2007). Thus clinicians need to be cautious in prescribing opiates, such as Vicodin, especially when the drugs will be used for long periods.

depressanTs In contrast to stimulants, depressants reduce behavioral and mental activity by slowing down the central nervous system. Anti-anxiety drugs, such as benzodiazepines, commonly given to calm people and reduce worry, are depressants. In large doses, depressants can cause sleep, which is why they are sometimes referred to as sedatives. Chapter 15, “Psychological Treatments,” discusses the clinical use of depressants.

Depressants produce their effects by activating GABA receptors. Recall from Chapter 2 that GABA is the primary inhibitory neurotransmitter in the brain. Through their effects on GABA receptors, depressants inhibit neural activity, which may be why they are experienced as relaxing. Alcohol is the most widely used depressant—in fact, it is the most widely used and abused drug.

Perhaps you know someone who drank a lot of alcohol, experienced a blackout, and can’t remember the details. Alcohol is a depressant that, like other addictive drugs, may offer its rewards by activating dopamine receptors. But it also inter- feres with the neurochemical processes involved in memory, and memory loss can follow excessive alcohol intake. Heavy long-term alcohol intake can cause extensive brain damage. Korsakoff ’s syndrome, a disorder sometimes caused by alcoholism, is characterized by both severe memory loss and intellectual deterioration.

FIGURE 3.23 early heroin ad Before 1904, Bayer advertised heroin as

“the sedative for coughs.”

HOW DO DRUGS ALTER CONSCIOUSNESS? ■ 109

addiction Compulsive drug craving and use, despite

the negative consequences of using the

drug.

tolerance A physical effect of addiction that occurs

when a person needs to take larger doses

of a drug to experience its effect.

withdrawal A physical and psychological effect of

addiction that occurs when a person

experiences anxiety, tension, and cravings

after discontinuing use of an addictive drug.

Many societies have a love/hate relationship with alcohol. On the one hand, moderate drinking is an accepted part of social interaction and may even be good for health. On the other hand, alcohol is a major contributor to many soci- etal problems, such as spousal abuse and other forms of violence. Although the percentage of traffic fatalities due to alcohol is dropping, alcohol is a factor in more than one-third of fatal accidents (Mayhew, Brown, & Simpson, 2002). One study found that approximately one-third of college students reported having had sex during a drinking binge, and the heaviest drinkers were likely to have had sex with a new or casual partner (Leigh & Schafer, 1993), thus increasing their risk for exposure to sexually transmitted diseases. The overall cost of problem drink- ing in the United States—including lost productivity due to employee absence, health care expenses, and so on—is estimated to be more than $100 billion each year.

In every region of the world, men drink a lot more than women across a wide variety of measures (e.g., drinking versus abstinence, heavy drinking versus occasional drinking, alcohol-related disorders). Men are twice as likely to report binge drinking (having five or more drinks in one evening), chronic drinking, and recent alcohol intoxication (Patrick et al., 2013). Gender gaps in binge drinking may be smaller among university students, however (Swendsen et al., 2012).

Alan Marlatt is a leading researcher on substance abuse. Marlatt (1999) has noted that in many cultures, people view alcohol as the “magic elixir,” capable of increasing social skills, sexual pleasure, confidence, and power. They antici- pate that alcohol will have positive effects on their emotions and behavior. For example, people tend to think that alcohol reduces anxiety, so both light and heavy drinkers turn to alcohol after a difficult day. Alcohol can interfere with the way the brain processes suggestions of threats, so anxiety-provoking events may be less troubling when people are intoxicated. However, this effect occurs only if people drink before the anxiety-provoking events. In fact, according to the research, drinking after a hard day can increase people’s focus on and obsession with their problems (Sayette, 1993). What’s more, although moderate doses of alcohol are associated with more-positive moods, larger doses are associated with more- negative moods.

Expectations about alcohol’s effects are learned very early in life, through observation. Children may see that people who drink seem to have a lot of fun and that drinking is an important part of many celebrations. Teenagers may view drinkers as sociable and grown up, two things they desperately want to be. Studies have shown that children who have very positive expectations about alcohol are more likely to start drinking and become heavy drinkers than chil- dren who do not share those expectations (Leigh & Stacy, 2004).

Addiction Has Physical and   Psychological Aspects addiction is behavior that remains compulsive despite its negative consequences. Addiction to drugs and alcohol has both physical and psychological factors. In physical dependence, a user develops tolerance to the substance, needing to consume more to achieve the same subjective effect (Figure 3.24a). If the user fails to ingest the substance, he will experience symptoms of withdrawal, a physi- cal and psychological state characterized by feelings of anxiety, tension, and crav- ings for the addictive substance.

110 ■ chapTer 3 CONSCIOUSNESS

The physical symptoms of withdrawal vary widely from drug to drug and from individual to individual. The symptoms commonly include nausea, chills, body aches, and tremors. A person can be psychologically dependent, however, without showing tolerance or withdrawal. Though we focus here on addiction to substances that alter consciousness, people can also become psychologically dependent on behaviors, such as shopping or gambling (Figure 3.24b).

How do people become addicted? One central factor appears to be dopamine activity in the limbic system, which underlies the rewarding properties of taking drugs (Baler & Volkow, 2006). As a powerful reinforcer, any behavior that leads to increased dopamine activity is likely to be repeated. Activating dopamine recep- tors leads to both pleasure and the desire to take more of the drug. It is possible that genes predispose some people to be more responsive to the reinforcing prop- erties of drugs, making them more vulnerable to addiction.

Only about 5 percent to 10 percent of people who use drugs become addicted. Indeed, more than 90 million Americans have experimented with illicit drugs, yet most of them use drugs only occasionally or try them for a while and then stop. Further, Jonathan Shedler and Jack Block (1990) found that people who had experimented with drugs as adolescents were better adjusted in adulthood than both people who had never tried them and people who were heavy users. This finding does not suggest, however, that everyone should try drugs or that parents should encourage drug experimentation. We cannot know in advance how an indi- vidual will react to a drug.

Though we can’t predict who will become addicted, we can identify some adolescents who are especially likely to experiment with illegal drugs and to abuse alcohol. Children who are attracted to novelty and risk-taking and have poor relationships with their parents are more likely to associate with trouble- making peers and to use alcohol, tobacco, and drugs (Wills, DuHamel, & Vaccaro, 1995). It is also possible that an inherited predisposition to sensation seeking may predict behaviors, such as affiliating with drug users, that increase the possibility of substance abuse.

FIGURE 3.24 physical dependence versus psychological dependence In addiction, both types of dependence can force people to go to extremes. (a) In physical dependence, a person develops a tolerance to the effects of a drug. As a result, the person must consume more of the drug to prevent the

adverse physical side effects of withdrawal. Someone addicted to alcohol might even abuse products that contain

alcohol, such as cough syrup. (b) Casinos encourage a psychological dependence on gambling. People suffering from this dependence spend increasing amounts of time and money gambling, to the point where their lives are seriously

disrupted.

(a) (b)

HOW DO DRUGS ALTER CONSCIOUSNESS? ■ 111

■ People can physically alter their consciousness by using drugs that change

the way they think, feel, and act.

■ Commonly used psychoactive drugs—such as cocaine, amphetamines,

MDMA, opiates, and alcohol—produce psychological and behavioral effects by

affecting neurotransmitter systems.

■ Alcohol is the most widely abused drug. There are pronounced gender

differences in alcohol use across all societies.

■ Excessive drug use can lead to addiction. Addiction is characterized by

physical dependence, with tolerance and withdrawal, and by psychological

dependence.

■ Addiction is influenced by personality factors, such as sensation seeking.

The environment, or the context in which drug use occurs, also influences

addiction.

3.4 checKpoinT: How Do Drugs Alter Consciousness?

Indeed, there is some evidence for genetic components of addiction, especially alcoholism. There is little direct evidence, however, for a single “alcoholism” or “addiction” gene. Instead, people inherit a cluster of characteristics. Inherited factors such as risk-taking and impulsivity, a reduced concern about personal harm, or a predisposition to finding chemical substances pleasurable may make some people more likely to explore drugs and enjoy them.

Does the family or social environment determine alcohol and drug use? Social learning theorists have emphasized the roles of parents, the mass media, and peers, including self-identification with high-risk groups (e.g., “stoners” or “druggies”). Teenagers want to fit in somewhere, even with groups that society perceives as deviant. Children imitate the behavior of role models, especially those they admire or identify with. Consider children who, during their preschool and elementary school years, have seen their parents drinking alcohol routinely. These children tend to have positive attitudes about alcohol and to begin drinking early (Sher, Grekin, & Williams, 2005).

112 ■ chapTer 3 CONSCIOUSNESS

BIG QUESTION LEARNING GOALS

a. Remember the key terms about consciousness.

b. Apply the two levels of consciousness.

c. Analyze the impact of unconscious processing.

d. Apply the global workspace model to your life.

e. Understand consciousness in a person with a split brain.

3.1 What Does It Mean 

to Be Conscious?

a. Remember the key terms about altered states of consciousness.

b. Apply altered states of consciousness to your life.

c. Understand how hypnosis affects consciousness.

d. Understand how meditation and flow may alter consciousness.

3.3 What Is an 

Altered State of 

Consciousness?

a. Remember the key terms about sleep.

b. Analyze how brain activity reveals four stages of sleep.

c. Apply the three reasons people need to sleep.

d. Understand the five common sleep disorders.

3.2 How Does 

Sleep Affect 

Consciousness?

a. Remember the key terms about drugs.

b. Apply the effects of the four classes of psychoactive drugs.

c. Understand how each drug within the four classes alters peoples’ state of consciousness.

d. Analyze the two aspects of addiction: tolerance and withdrawal.

3.4 How Do Drugs Alter 

Consciousness?

B IG

P IC

T U

R E

KEY TERMS CHECKPOINT

■ Consciousness is how the brain allows us to be aware of and experience the external world and our internal mental activity.

■ There are two levels of consciousness, which vary in the amount of attention to and awareness of our experiences.

■ Information that is processed subliminally—that is, without conscious awareness—can influence basic thinking and behavior for only short periods of time.

consciousness subliminal perception global workspace model split brain

■ Normally, our state of consciousness allows us to experience the external world and our thoughts clearly. Altered consciousness makes the outer world more or less vivid and our thoughts more or less organized.

■ Patterns of brain activity suggest that people who have been hypnotized experience a shift in consciousness and are not simply faking it.

■ Altered states of consciousness may be achieved through three forms of meditation.

■ In cases of extreme physical exertion or profound religious experiences, people can experience a type of altered consciousness called a flow state.

hypnosis sociocognitive theory of

hypnosis dissociation theory of hypnosis meditation flow

■ Three theories have been proposed to explain why sleeping is beneficial.

■ Five disorders affect the experience of sleeping.

■ We experience changes in consciousness when we sleep as we become less aware of the external world, yet we are still able to respond when necessary.

■ Sleep has four stages. Each stage is characterized by brain activity that is the basis for how we experience that stage of sleep.

■ We dream differently during REM sleep than during non-REM sleep.

circadian rhythms melatonin slow-wave sleep REM sleep dreams activation-synthesis theory insomnia sleep apnea narcolepsy

■ People can physically alter their consciousness by using drugs that change the way they think, feel, and act.

■ Commonly used psychoactive drugs— such as cocaine, amphetamines, MDMA, opiates, and alcohol—produce psychological and behavioral effects by affecting neurotransmitter systems.

■ Alcohol is the most widely abused drug. There are pronounced gender differences in alcohol use across all societies.

■ Excessive drug use can lead to addiction. Addiction is characterized by physical dependence, with tolerance and withdrawal, and by psychological dependence.

■ Addiction is influenced by personality factors, such as sensation seeking. The environment, or the context in which drug use occurs, also influences addiction.

stimulants depressants opiates hallucinogenics addiction tolerance withdrawal

BIG PICTURE ■ 113

■ Conscious experiences are a result of activity in five specific regions of the brain that cause us to be aware of specific types of information.

■ People with split brains have a unique experience of consciousness: They are aware of only information presented to the one hemisphere that processes that information. And they can verbalize only information processed in the left hemisphere.

For a self-quiz on this chapter, go to the back of the book and find Appendix B:  Quizzes.

Development Across the Life Span4

WHO ARE YOU RIGHT NOW? Are you the same person you were at 13, and 8, and 3?

Almost certainly the answer is no. As virtually all people do, you have changed in many

ways over the years.

Now look at Figure 4.1. How old do you think the infant was? Her name was Brooke

Greenberg, and in this photo she was 19 years old. She was being held by her younger

sister, 16-year-old Carly. In 1993, Brooke was born prematurely. At first, she seemed to

develop normally. But at about the age of 19 months, after various medical problems,

Brooke stopped growing. Her brain also seemed to stop changing developmentally. In

lots of ways, Brooke seemed to be “frozen” as a toddler.

BIG QUESTIONS 4.1 How Do We Develop in the Womb?

4.2  How Do Infants and Children Develop Over Time?

4.3  How Do Adolescents Develop?

4.4 How Do We Develop in Adulthood?

115115

Brooke was happy and laughed a lot. She enjoyed music and shopping

trips to the mall, but she refused to engage in activities she didn’t like. At

such times, Brooke’s family thought of her as a typically rebellious teenager.

However, she couldn’t speak, so she expressed herself with sounds like those

an infant would make. She couldn’t walk, so she traveled in a stroller. She had

the bone development of a 10-year-old, but she still had all of her baby teeth.

She wore diapers. Her family took care of Brooke her entire life. When she

died, in 2013, she was 20 years old but still looked like a toddler.

Brooke’s stalled development in many, but not all, areas baffled doctors

over the years. They named the unknown cause of Brooke’s disjointed devel-

opment Syndrome X. Her condition was extremely rare, but by working to

understand why Brooke did not develop and age, scientists may have begun

to better understand the changes that occur throughout all of our lives.

FIGURE 4.1 Brooke Greenberg: The Infant Who Didn’t Change Brooke Greenberg was 19 years old here

and was being held by her younger sister.

In most ways, Brooke looked and acted

like a toddler. The fact that Brooke did not

grow or change may provide insight into

“normal” human development.

Brooke Greenberg gave us a rare opportunity to learn about how humans develop. Unlike Brooke, people normally change, but many of these changes happen so slowly that we don’t notice them in ourselves or in people around us. The 2014 movie Boyhood gives us a fascinating opportunity to see what happens over 12 years in the lives of fictional characters: Mason Evans Jr.; his older sister, Samantha; and his parents, Olivia and Mason Sr. What’s special about the movie is that it was actually filmed over 12 years, so we also see how the actors in the movie changed in real life. For example, the actor who played Mason, Ellar Coltrane, began filming the movie at age 6 and ended at age 18 (Figure 4.2). According to Coltrane, the director of the movie, Richard Linklater, “would ask me about similar experiences that I had had to what Mason might be going through, and the different dynamics between me and friends, girlfriends or family members.” In Boyhood, Linklater created a movie that truly shows how people change over time.

Developmental psychology explores how all of us grow in our lifetimes. These changes are a result of both nature (our genetics and biology) and nurture (the envi- ronment around us). Together, nature and nurture influence growth in three devel- opmental domains: physical, socio-emotional, and cognitive. Changes in the physical domain revolve around growth in the brain, hormones, and body. For example, in Boyhood, we see how Mason physically develops from a chubby-faced young boy into a tall, muscular teenager, while his sister blooms into a curvaceous young woman.

4.1 How Do We Develop in the Womb?

LEARNING GOALs READING ACTIvITIEs

a. Remember the key terms related to prenatal

development.

List all of the boldface words and write down their

definitions.

b. Understand the three prenatal periods. Summarize in your own words the physical changes that

occur in each period.

c. Apply information about teratogens and their effects

during prenatal development.

Describe three hypothetical cases showing the effects of

teratogens during prenatal development.

d. Analyze how biology and environment affect prenatal

development.

Organize a table showing how nature and nurture each

affect prenatal development.

116 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

developmental psychology The scientific study of how humans change

over the life span, from conception until

death.

HOW DO WE DEvELOp IN THE WOmB? ■ 117

Development in the socio-emotional domain includes how we understand ourselves, interact with others, and experience and regulate emotions. In the movie, we see socio-emotional development in Mason and his parents as they struggle to find who they are, improve themselves, or make strong emotional connections with others. Lastly, changes in the cognitive domain pertain to how our ability to think, reason, and communicate change over time. In Boyhood, Mason grows cognitively from thinking about concrete ideas, such as how to sharpen rocks, to abstract thoughts about how to create art.

Let’s look at how nature and nurture both influence our development in these domains by exploring our growth across four phases of our lives: in the womb, through infancy and childhood, in adolescence, and during adulthood.

Prenatal Development Includes Three Phases of Physical Growth Do you think that who you are right now has been influenced by development in your mother’s womb? This idea may surprise you, but it’s true. We begin life as just two cells, and about 40 weeks later we are born. This critical time in the prenatal period includes in three major periods of physical growth.

The germinal period begins with conception, when the sperm from the male unites with the egg from the female (Figure 4.3a). This union creates the zygote, the first cell of a new life. The zygote begins to divide rapidly into 2 cells, then 4 cells, then 8 cells, and so on (Figure 4.4a). A placenta begins to form to nourish and protect these cells. Just 7 or 8 days after fertilization, implantation occurs in the uterine wall, and the next stage of development begins. If any abnormalities occur during this earliest stage of development, the result is usually a miscarriage before the woman even knows she is pregnant.

germinal period The period in prenatal development from

conception to two weeks after conception,

when the zygote divides rapidly and

implants in the uterine wall.

FIGURE 4.3 Development in the Womb (a) In the germinal period, the union of egg and sperm forms a zygote that implants in the uterine wall within 2

weeks. (b) In the embryonic period, the organs develop in the embryo. (c) The fetal period, from 2 months until birth, is a time of tremendous physical growth and brain

development that prepares the baby to survive outside

the womb.

(a) (b) (c)

FIGURE 4.2 Boyhood Reveals 12 Years of Human Development In 2014, the movie Boyhood depicted how the members

of one family developed

physically, socio-emotionally,

and cognitively, as it filmed the

actors over 12 years of their lives.

The main character was the son,

mason, played by Ellar Coltrane.

(a) Here is mason/Ellar at age 6, when filming began. (b) And here he is at age 18, when filming

ended.

(a)

(b)

118 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

From about 2 weeks to 2 months, the developing human is known as an embryo (Figure 4.3b). The embryonic period is the most important time for physi- cal development of the spinal cord, brain, and all internal organs, including the heart, lungs, liver, kidneys, and sex organs (Figure 4.4b). This stage is consid- ered to be the critical time for organ formation. If development goes wrong, the organ(s) will develop improperly, and miscarriage or birth defects may result. For example, if the mother has not consumed enough of the nutrient folic acid during the first month of prenatal development, the embryo’s spinal cord and brain may not develop properly. If the embryo then survives, the baby may be born with serious birth defects, such as spina bifida. For this reason, women who want to become pregnant are encouraged to eat foods such as spinach, broccoli, citrus fruits, beans, and avocado, which contain folic acid, or to take prenatal vitamins containing folic acid (Figure 4.5).

From 2 months until birth, the growing human is called a fetus (Figure 4.3c). During this fetal period, no new structures develop, but the whole body continues to change physically (Figure 4.4c). For example, at about 4 months the fetus begins to move its muscles; a first-time mother might feel these movements by about the fifth month. The eyes and eyelids finish developing at 6 months. The organs also finish developing, so the infant, once it is born, can breathe on its own and digest food it eats. In the last 3 months of prenatal growth, the fetus develops fat under its skin and increases dramatically in length and weight. While the fetus is growing

embryonic period The period in prenatal development from

2 to 8 weeks after conception, when the

brain, spine, major organs, and bodily

structures begin to form in the embryo.

fetal period The period in prenatal development from

8 weeks after conception until birth, when

the brain continues developing, bodily

structures are refined, and the fetus grows

in length and weight and accumulates fat

in preparation for birth.

FIGURE 4.4 physical Changes in the Three prenatal periods

(a) Germinal period (weeks)

Stage (b) Embryonic period (weeks)

Major defects in structure

PHYSICAL DEVELOPMENT

Physiological defects and minor defects in structure

(c) Fetal period (weeks)

1Weeks 2 3 4 5 6 7 8 12 16 20-36 38

Teratogens affect development of these structures.

Heart

Central nervous system

Eye Heart EarBrain Ear Palate

Brain Ear

Teeth

Arm Leg

External genitalia

Central nervous system

Heart

Arms

Eyes

Legs

Teeth

Palate

External genitalia

Ears Teratogens do not

affect development, but miscarriage

can occur. ABNORMALITIES

HOW DO WE DEvELOp IN THE WOmB? ■ 119

larger, its brain also matures. The brain begins to process sensory input and motor output, and basic thinking begins.

Most healthy full-term pregnancies end with the birth of the baby between 38 and 42 weeks. However, the fetus is thought to be fully developed and able to live outside of the womb at 28 weeks of gestation. Modern medical technology has made it possible for a fetus to live outside the womb much earlier in its develop- ment. For example, about half of infants born at 25 weeks of gestation survive, and up to 10 percent of fetuses born at 22 weeks of gestation now survive outside the womb. For example, Amillia Sonja Taylor was born in 2006, after spending just 21 weeks and 6 days in the womb (Figure 4.6).

We don’t always know what causes premature birth, although it is likely that genetics, nutrition, and environment all play roles. Clear risk factors for premature birth are parental smoking, drinking, and drug use. Babies who are born prema- turely have a greater risk of dying as infants. They also may have disabilities, such as cerebral palsy, breathing and feeding problems, and vision and hearing deficits. In addition, prematurity can have long-term effects on intellectual development and school performance (Nomura et al., 2009). But this is not always the case. After a rough start, baby Amillia is now a healthy and successful child.

Substances Affect Prenatal Development in All Three Domains Smoking, drugs, alcohol, and pollutants are just some of the substances that can make us sick. But a developing human can also be harmed by these substances. The same placenta that provides oxygen and nutrients to the baby helps protect it from harmful stimuli. Even so, some substances can pass through the placenta and sometimes have terrible consequences.

TERATOGENs Teratogens (from the Greek tera, which means “monster”) are substances that cause birth defects. As shown in the Learning Tip on p. 120, there are several classes of teratogens. The impact of each one depends on when exposure occurs and how long it lasts during prenatal development. The physical impact of some teratogens can be obvious at birth. However, some teratogens have effects that are not apparent until the child is much older, including disorders involv- ing language, reasoning, attention, social behavior, and/or emotions. There are no standards about how much exposure to any teratogen is safe for normal develop- ment. Even small exposure to teratogens can sometimes have terrible effects.

DRUGs AND ALCOHOL The use of recreational drugs—such as opiates, coca ine, or marijuana—during pregnancy can affect the mother and the developing human. They can also affect long-term development during childhood and beyond. Unfortunately, recent surveys in the United States show that about 4.4 percent of pregnant women aged 15–44 years use these drugs (Behnke & Smith, 2013).

Premature birth and other complications have been associated with the use of all these drugs during pregnancy (Gillogley, Evans, Hansen, Samuels, & Batra, 1990; Sherwood, Keating, Kavvadia, Greenough, & Peters, 1999). For instance, babies of women taking opiates, particularly methadone, have two to three times greater risk for unexplained sudden death in infancy (Davidson Ward et al., 1990). Cocaine use has also been linked to sudden infant death (Hulse, Milne, English, & Holman, 1998; Kandall & Gaines, 1991). Among infants exposed to opiates

FIGURE 4.6 A Case of Extreme prematurity At birth, Amillia Sonja Taylor was a little

longer than a ballpoint pen, and she

weighed 10 ounces—less than the weight of

a can of soda. Today she is a healthy child.

FIGURE 4.5 The Importance of Folic Acid Nutritional deficiencies can cause serious

birth defects. This mom-to-be is doing the

right thing. Eating dark leafy greens, such as

spinach, can help her baby’s spine and brain

develop.

teratogens Environmental substances that can harm

prenatal development.

120 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

during prenatal development, 55 percent to 94 percent show symptoms of withdrawal as newborns, including irritability, high-pitched crying, tremors, vomiting, diarrhea, and rapid breathing (American Academy of Pediatrics, 1998).

We’ve been talking about how a woman’s behavior before or during pregnancy might affect her baby, but mothers are only half the story when it comes to prenatal development. Potential fathers, as well as mothers, must be cautious about their diets, exposure to toxins, and use of substances. Less research has been done on how men’s health and lifestyles relate to prenatal development. However, there is evidence that fathers’ behaviors affect sperm, which in turn influences prenatal development. For example, paternal smoking may be related to infant hydrocephalus (a dangerous excess of fluid in the brain), and pater- nal alcohol use is related to infant heart defects (Savitz, Schwingle, & Keels, 1991).

Both women and men can impair prenatal development with the most commonly used teratogen: alcohol. Women who drink alcohol when pregnant are gambling with their baby’s development, because alcohol can lead to various defects. The most severe disorder is fetal alcohol syndrome (FAS), which results in abnormalities such as a small head, malformations of the face and limbs, heart defects, and abnormal brain development (Abel, 2006; Figure 4.7). Besides these physical impairments, FAS babies often have a low birth weight, slight mental retardation, and behavioral and cognitive problems (Guerri, 2002). In the United States, about 1 in 8 unborn babies is exposed to alcohol and the risks associated with it (Olson et al., 2009). For this reason, many health workers recommend that women completely avoid drinking any alcohol when they are pregnant or trying to become pregnant (Mukherjee, Hollins, Abou-Saleh, & Turk, 2005). We now know that men might want to follow the same advice.

This table will help you understand the various classes of teratogens and their effects on prenatal development.

LEGAL DRUGs

ALCOHOL: fetal alcohol syndrome, facial malformations, mental retardation, learning difficulties

NICOTINE: miscarriage, still birth, low birth weight, mental retardation, learning difficulties

CAFFEINE: miscarriage, low birth weight

RECREATIONAL DRUGs

COCAINE: low birth weight, breathing problems, seizures, learning difficulties, irritability

MARIJUANA: irritability, nervousness, tremors

INFECTIONs

GERMAN MEAsLEs (RUBELLA): blindness, deafness, heart defects, brain damage

sYpHILIs: mental retardation, deafness, meningitis

ENvIRONMENTAL FACTORs

RADIATION (x-RAYs): higher incidence of cancer, physical deformities

MERCURY: mental retardation, blindness

LEARNING TIp: Types of Teratogens

FIGURE 4.7 Fetal Alcohol syndrome Compare (left) the brain of a normal 6-week-old baby with (right) the seriously deformed brain of a baby of the same age with fetal alcohol syndrome

(fAS).

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 121

4.2 How Do Infants and Children Develop Over Time?

Have you ever seen a newborn baby? Do they seem completely helpless? In fact, babies arrive in the world with basic abilities that aid their survival. In infancy, beginning at birth and lasting between 18 and 24 months, babies can suck for nour- ishment and see the face of a caregiver who feeds them. They can cry when hungry, which makes parents want to feed them. Infants also smile and bond with care- givers, which develops attachments that aid their survival. And they can remem- ber and learn. These abilities aid infants’ survival until childhood, which lasts from age 2 until about ages 11 to 14. Both infancy and childhood are times of great change across all three developmental domains: physical, cognitive, and socio-emotional.

Infants and Children Change Physically As infants and children develop, the brain changes in two critical ways. First, myelinated axons form synapses with other neurons. Recall from Chapter 2 that myelin ensures efficient communication between neurons by functioning like the plastic that insulates electrical wires. The synaptic connections between neurons let regions of the brain communicate to process information. More of

LEARNING GOALs READING ACTIvITIEs a. Remember the key terms about how infants and children

develop.

List all of the boldface words and write down their

definitions.

b. Understand physical development in an infant. Summarize these motor and sensory changes in a table

using your own words.

c. Apply socio-emotional aspects of child development to

real life.

Describe the attachment style and temperament of an

infant or child you know.

d. Understand the four stages of cognitive development in

children.

Summarize the main aspects of development in each of the

stages using your own words.

e. Analyze the three stages of language development in

childhood.

Organize the three stages of development in a table that

includes the typical age of the child and an example of

what they might say.

■ Developmental psychology explores growth in terms of how both nature

(inborn genetics and biological traits) and nurture (environment) affect

human development.

■ Human development occurs in three interacting domains: physical,

socio-emotional, and cognitive.

■ prenatal physical development occurs in three periods: germinal, embryonic,

and fetal.

■ Teratogens are environmental substances that negatively affect prenatal

development. They may have long-term effects on physical, cognitive, and

socio-emotional development.

4.1 CHECKpOINT: How Do We Develop in the Womb?

122 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

these connections develop than the infant brain will ever use, but this growth gives every brain the chance to adapt well to any environment. Second, over time and with experience, the synaptic connections change. Connections that are not used will decay and disappear. The loss of connections might seem like a bad thing, but it lets the brain process information more efficiently.

Unfortunately, sometimes infants and young children are raised in environments that do not stimulate their brains (Figure 4.8a). In these cases, very few synaptic connections are made. As a result, these under-stimulated brains will be less able to process complex information, solve problems, or allow the children to develop advanced language skills (Perry, 2002; Figure 4.8b, left side). But the reverse is also true: When infants and young children are able to explore the external world, and when they have ample opportunities to move, talk, and read, their brains are stimu- lated (Figure 4.8c). In short, when the brain is stimulated, the brain is encouraged to develop (Figure 4.8b, right side). And when the brain develops, it can support the individual’s rich physical, socio-emotional, and cognitive development.

INBORN REFLExEs Babies come into the world hardwired with basic motor reflexes that aid survival. For example, infants must eat in order to grow, and they are born with innate, unlearned reflexes that help them find food. When an infant is stroked at the corner of her mouth, she will show the rooting reflex. That is, she turns and opens her mouth in anticipation of food (Figure 4.9a). If she finds a nipple where she has turned, the infant will show the sucking reflex. Automatically closing her mouth on the nipple, she will begin to suck to eat (Figure 4.9b).

Another inborn reflex that aids survival is the grasping reflex (Figure 4.9c). If you stroke an infant’s palm, he automatically curls his fingers around the stroked area (see the Try It Yourself feature on p. 124). Some scholars believe that this survival mechanism persists from our prehistoric ancestors. Young primates need to be

FIGURE 4.8 Environmental stimulation and Brain Development (a) Some infants and children are raised in environments that provide little stimulation or

comfort. (b) These images illustrate the impact of neglect on the developing brain. The brain scan

on the left is from a 3-year-old child with minimal

exposure to language, touch, and social interaction,

who has a significantly smaller head. The brain scan

on the right is from a healthy 3-year-old child with an

average head size. (c) The best brain development takes place in environments with rich stimulation and

comforting contact with caregivers.

(a)

(b)

(c)

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 123

carried from place to place, so grasping their mothers is an adaptive reflex. Though such inborn reflexes help infants survive in the first months of life, being able to move on purpose is another matter entirely. Babies have to learn these motor skills.

MOTOR sKILLs Have you ever watched an infant trying to lift her head to look around? At first, the infant’s head wobbles on weak neck muscles. (This is why it is so important to cradle a baby’s head in your hand, so you can help control the head until the baby learns to do so herself.) It takes a lot of practice for the infant to learn to move her head—for example, to turn toward a voice she recognizes.

In the first years of life, children progress from moving their heads to sitting up, standing, and walking. The process of developing these motor skills is a sequence of steps that usually occur within a predictable range of ages. The process is called maturation (Figure 4.10). Maturation was originally thought

maturation physical development of the brain and

body that prepares an infant for voluntary

movement, such as rolling over, sitting, and

walking.

FIGURE 4.10 physical Maturation and Learning to Walk Usually, a human baby learns to walk without formal teaching, in a sequence that is typical of

most humans. However, the age when a child develops a certain skill varies a lot, so the average

age of acquisition is shown here. A child might deviate from this sequence—for example, by

skipping the crawling phase—yet still develop normal walking abilities.

Average age of motor skill acquisition (months) 0 1 2 3

Roll over (2.8 months)

Raise head to 45 degrees

(2 months) Sit with support

(4 months) Stand holding on (5.8 months)

Pull self to standing position

(7.6 months) Crawl and creep

(10 months, but many babies skip this stage)

Walk without assistance

(12.1 months)

Sit without support (5.5 months)

Walk holding on to furniture (9.2 months)

Stand alone (11.5 months)

4 5 6 7 8 9 10 11 12 13

(a) (b) (c)

FIGURE 4.9 Infant Reflexes Infants are born with innate abilities that

help them survive, including the (a) rooting reflex, (b) sucking reflex, and (c) grasping reflex.

124 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

to be determined only by nature, not by nurture. For an example of nature’s effects on development, consider that Brooke Greenberg could not walk primarily because of her biological deficits. But then, even in cases of normal brain development, occasionally an infant skips a step in maturation. The fact that not all babies crawl is an example of how nurture also affects maturation.

When infants sleep on their backs, they often skip the crawling phase. Perhaps infants who sleep on their backs do not develop the stomach muscles needed to crawl. In any case, pediatricians strongly recommend that infants sleep on their backs. Why? Since the mid- 1980s, research has shown that placing infants on their backs for sleeping reduces the incidence of sudden infant death syndrome (SIDS). Preventing SIDS is far more important than making sure that babies crawl before walking. And skipping the crawling phase does not affect long-term motor development! So some differ- ences in maturation, caused by how an individual is nurtured, can be perfectly natural. You have to consider the circumstances.

DYNAMIC sYsTEMs pERspECTIvE Development in physical, socio-emotional, and cognitive domains is a result of complex interactions. The factors involved are the person’s biology, the person’s active exploration of an environment, and the constant feedback provided within the person’s culture (Smith & Thelan, 2003). The dynamic systems theory of development can be seen in the way that children often achieve developmental milestones at different paces, depending on the culture in which they are raised (Figure 4.11).

TRY IT YOURsELF: Survival Reflexes

If you know a newborn or a young infant, you can observe

the innate survival reflexes. The baby can be anywhere

from a day old to several months old, though babies show

these reflexes less as they develop. Be sure to try this

exercise when the baby is fully awake and alert and is in

a comfortable and safe position—for example, nestled in

a caretaker’s arms. But don’t freak out if the baby doesn’t

display the expected results. Some deviation is perfectly

acceptable. Anyone concerned about the development of

a particular infant should seek the advice of a pediatrician.

Rooting reflex: Gently caress the baby’s cheek down to the corner of his mouth. The baby should turn his head

toward the cheek that was stroked and might even open

his mouth a bit.

sucking reflex: If you have engaged the rooting reflex and the infant has opened his mouth, place the rubber tip

of a pacifier or a baby bottle in the baby’s mouth. He may

start to suck.

Grasping reflex: place a finger in the palm of the baby’s hand, or gently stroke his palm, and the baby will close his

fingers over his palm, perhaps around your finger.

FIGURE 4.11 Dynamic systems Theory Throughout life, every new behavior

results from interactions between a

person’s biology and that person’s cultural

and environmental contexts.

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 125

As an example of the dynamic systems theory of development, one study (Super, 1976) focused on the motor development of Kipsigi infants in western Kenya. Kipsigi parents in the Kohwet village placed their babies in shallow holes in the ground so the babies could practice sitting upright. The parents also marched their babies around while placing their own arms under the babies’ arms, so the children could practice walking. These infants walked about 1 to 2 months earlier than American and European infants who spent a lot of time in cribs and playpens. But what about middle-class Kipsigi families who had moved to Westernized homes in a larger city? They let their infants both sleep in cribs and lie in playpens like their Western counterparts. However, they still deliberately taught their infants motor skills using traditional Kipsigi methods. These urban Kipsigi infants walked 2 weeks later than the rural infants in Kohwet but 1 week earlier than infants in Boston, Massachusetts. Clearly, the Kipsigi culture influences maturation differently depending on the environment.

sENsORY DEvELOpMENT To learn, infants need information. They get infor- mation from the world by hearing, seeing, smelling, tasting, and perceiving touch. Some of these sensory abilities are more fully developed at birth than others. The earliest fully developed sensory abilities are directly connected with the infant’s survival. For instance, 2-hour-old infants prefer sweet tastes to all other tastes (Rosenstein & Oster, 1988). This preference makes sense because breast milk is sweet, so infants are born with a built-in mechanism that makes them want to drink this nutritious milk. Infants also have a good sense of smell, especially for scents associated with feeding.

When infants are born, they can also hear quite well. They startle at loud sounds and turn their heads in the direction of everyday sounds. Infants even hear well enough to prefer specific sounds. For instance, a newborn can change her sucking pattern in order to hear her mother’s voice (DeCasper & Fifer, 1980). The newborn’s ability to recognize and discriminate her mother’s voice makes sense because a fetus starts hearing that voice inside the womb at 4½ months. Infants’ abilities to recognize and locate sounds improve as they gain expe- rience with objects and people and as the auditory cortex develops further. By the age of 6 months, babies hear nearly as well as adults (DeCasper & Spence, 1986).

By contrast, newborns have quite poor vision. Initially they can see only about 8–12 inches from their heads and cannot make out differences between colors. They can see high-contrast patterns better than they see patches of gray (Fantz, 1966; Figure 4.12). These visual abilities are adaptive, because they let the infant focus on what is most important: the mother’s breast, which provides nutrition, and her face, which provides important social information.

By about 2 months, infants can see blue, green, and red. Their visual acuity for distant objects increases rapidly over the first 6 months (Figure 4.13; Teller, Morse, Borton, & Regal, 1974). As long as babies have access to rich visual experiences and the brain and parts of the eye develop normally, they can see in a way that is similar to adults when they are about a year old. Once again, devel- opment occurs thanks to complex interactions of dynamic systems.

FIGURE 4.12 Babies Are Born Able to see High Contrast The innate ability to see large blocks of

black and white helps a baby survive.

It lets the baby locate her mother’s

nipple, which contrasts in color with the

surrounding tissue, in order to eat.

FIGURE 4.13 Infants’ visual Abilities Improve With Experience Newborns have poor visual acuity and poor ability to see

colors. These capacities improve rapidly over the first 6

months of life. At about a year of age, the infants’ visual

abilities are similar to those of adults.

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Infants and Children Change Socially and Emotionally Humans are social animals. We spend a good part of our lives getting along with other people, or trying to. How do we learn how to do it? Infants and children develop socially and emotionally by interacting with others. Our early experi- ences with our primary caregivers—such as a mother, a father, a grandparent, a day care teacher—are critical for developing the bonds that are essential for socio- emotional development.

EARLY ATTACHMENT All infants—including those with brain damage and disabilities, such as Brooke Greenberg—have a fundamental need to form strong connections with caretakers. These connections help aid the infants’ survival. In order to develop these connections, all infants innately behave in ways that motivate adults to care for them over time and across situations (Bowlby, 1982).

For example, an infant can cry immediately after birth. The crying causes caregivers to respond, typically by offering the newborn comfort, food, or both. In virtually every culture studied, men, women, and children raise the pitch of their voices when talking to babies. They know intuitively that babies can hear and will pay attention to high-pitched voices. In turn, the babies maintain eye contact with these people (Fernald, 1989; Vallabha, McClelland, Pons, Werker, & Amano, 2007). Eventually, between 4 and 6 weeks of age, infants display a first social smile, which creates powerful feelings of love in caregivers (Figure 4.14). When babies’ inborn behaviors create these connections, how do caregivers care for them?

During the late 1950s, psychologists believed infants mainly needed care in the form of food from their mothers. However, the psychologist Harry Harlow wondered if care was really about providing food, or about something else (Harlow  &  Harlow,  1966). To investigate this question, as you can see in the Scientific Thinking feature, Harlow placed infant rhesus monkeys in a cage with two surrogate “mothers.” One mother was made of wire and provided milk through a bottle. The second mother was made of soft terrycloth, but did not give milk. Harlow found that the monkeys approached the wire mother, the mother with food, only when they were hungry. The rest of the day, they clung to the cloth mother. To these monkeys, caring was really about having comforting contact, so they became attached to the soft, cloth mothers.

To test this attachment, Harlow put a scary metal robot with flashing eyes and large teeth in the cage. Upon seeing the robot, the infants always ran to the cloth mother, never to the mother with food. Harlow repeatedly found that the infants were calmer, braver, and better adjusted overall when near the cloth mother. The mother- as-food theory of attachment was shown to be wrong. Harlow’s findings showed that comforting touch is critical in the socio-emotional development of infants.

vARIATIONs IN ATTACHMENT Clearly, infants need physical closeness with and comfort from caregivers to develop socio-emotional bonds. At about 8 to 12 months, however, the infants begin to crawl or toddle and start to move away from care givers. When they cannot see their attachment figures or are left with baby- sitters or strangers they don’t know, they often show signs of distress (Waters, Matas, & Sroufe, 1975; Figure 4.15). This phenomenon, separation anxiety, occurs in all human cultures. You’ve probably seen babies displaying separation anxiety. You can read about two typical situations in Has It Happened to You?

FIGURE 4.14 Infant Attachment Behaviors When newborns smile, it makes their

caretakers want to care for them.

Have you ever been in a room

with a baby when the parent left

for a minute? Or have you seen

an infant left with a babysitter

he didn’t know? How did the

infant react in these situations?

If he was 8–12 months old, he

probably started to cry. The infant

may have been experiencing

separation anxiety, a condition of

great distress when the caregiver

is out of sight. It is a completely

normal reaction for infants at

this age. The infant was most

likely fine as soon as a loved one

comforted him. In fact, you were

probably left more shaken by the

experience than the infant was!

HAs IT HAppENED

TO YOU?

Separation Anxiety

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 127

sCIENTIFIC THINKING: Attachment Is Due to Providing Contact

FIGURE 4.15 separation Anxiety (a) Beginning at about 8 months of age, infants show distress when separated from caregivers. (b) This separation anxiety increases dramatically as the infants approach their first year of life.

(a) (b)

5 6 7 8 9 10 0

20

40

60

Infants showing a certain reaction (percentage)

Age (months)

Any negative reaction

Wariness

Extreme distress

128 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

secure attachment The attachment style for most infants,

who are confident enough to play in

an unfamiliar environment as long as the

caregiver is present and are readily

comforted by the caregiver during times

of distress.

avoidant attachment The attachment style for infants who are

somewhat willing to explore an unfamiliar

environment, but do not look at the

caregiver when the caregiver leaves or

returns, as though they have little interest

in the caregiver.

ambivalent attachment The attachment style for infants who

are unwilling to explore an unfamiliar

environment but seem to have mixed

feelings about the caregiver—they cry

when the caregiver leaves the room,

but they cannot be consoled by the

caregiver upon the caregiver’s return.

To study variations in infant attachment, the developmental psychologist Mary D. Salter Ainsworth created the strange-situation test. In a playroom, a child, a caregiver, and a friendly but unfamiliar adult participate in a series of separations and reunions between the child and each adult. The researchers observe the test through a one-way mirror in the laboratory and record the child’s responses to the caregiver and the stranger. The strange-situation test has revealed the three attachment styles children might have (Ainsworth, Blehar, Waters, & Wall, 1978).

In secure attachment, the child is happy to play alone and is friendly to the stranger as long as the caregiver is present. When the caregiver leaves the play- room, leaving the child with the stranger, the child is distressed, whines or cries, and looks for the caregiver. When the caregiver returns, the child usually reaches out her arms to be picked up and is quickly comforted by the caregiver. The child then feels secure enough to return to playing (Figure 4.16a). Just as in Harlow ’s findings, the caregiver is a source of security in times of distress. When parents have a secure attachment style, approximately 60 percent to 65 percent of their children also show secure attachment ( Van IJzendoorn, 1995; Figure 4.17).

The remaining 35 percent to 40 percent of children display one of the types of insecure attachment (see Figure 4.17). Those with avoidant attach- ment do not get upset or cry at all when the caregiver leaves. They may even prefer to play with the stranger rather than the caregiver during their time in the playroom. They may also avoid the caregiver upon the caregiver’s return (Figure 4.16b). Those with ambivalent attachment may cry a great deal when the caregiver leaves the room, yet both seek and reject caring contact when the caregiver returns and tries to calm them down (Figure 4.16c). Insecurely attached infants have learned that their caregiver is not available, or only inconsistently available, to soothe them when they are distressed. These chil- dren may be emotionally neglected or actively rejected by the people who take care of them.

Decades of research show that secure attachment is related to better socio- emotional functioning in childhood, better peer relations, and successful adjust- ment at school (e.g., Bohlin, Hagekull, & Rydell, 2000; Granot & Mayseless, 2001).

FIGURE 4.16 The strange-situation Test This test is a method of exploring the attachment style of an infant or child. Attachment style

is based on (1) how the child responds when the caregiver leaves her with a stranger, and

(2) how the child responds when the caregiver returns. Shown here are (a) secure, (b) avoidant, and (c) ambivalent attachment styles.

(a) A secure child is distressed when the caregiver leaves. The child is also quickly comforted when the caregiver returns.

(b) An avoidant child is not distressed when the caregiver leaves.The child also avoids the caregiver when she returns.

(c) An ambivalent child is inconsolably upset when the caregiver leaves. The child will also both seek and reject caring contact when the caregiver returns.

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 129

In contrast, insecure attachments have been linked to poor outcomes later in life, such as depression and behavioral problems (e.g., Munson, McMahon, & Spieker, 2001). In cases of insecure attachment, interventions may help the caregivers learn the skills that increase the likelihood of forming secure attachments.

Infants and Children Change Cognitively Two-year-old Rowen is in her car seat looking at a book. She asks her father, who is driving the car, “What’s this?” Her father replies, “Sorry, I am looking at the road. I can’t see what you see there in the backseat.” But Rowen doesn’t understand, so she keeps asking the same question. Young children cannot put themselves in another person’s shoes to understand what that person senses, thinks, or feels. However, through exchanges such as this one, children begin to learn about the world around them. Rowen, like most children, will eventually realize that other people’s perspec- tives are different from her own. In other words, she will develop cognitively.

DEvELOpING THEORY OF MIND Infants take a big step in cognitive development when they begin to understand who they are. We know a child has this ability if she recognizes herself in a mirror. If there is an infant in your life, you can follow the steps in Try It Yourself to see if he has developed this cognitive ability.

Once an infant becomes self-aware enough to recognize herself in a mirror, she can learn that her thoughts are different from those of other people (Gergely  & Csibra, 2003; Sommerville & Woodward, 2005). The ability to understand that other people have minds and intentions is called theory of mind (Baldwin & Baird, 2001). In one study demonstrat- ing theory of mind in infants, an adult begins hand- ing a toy to an infant, but then stops. On some trials, the adult acts unwilling to hand over the toy, teas- ing the infant with the toy or playing with it herself. On other trials, the adult becomes unable to hand it over, “accidentally” dropping it or being distracted by a ringing telephone. Infants older than 9 months showed greater signs of impatience—for example, reaching for the toy—when the adult was unwilling than when the adult was unable (Behne, Carpenter, Call, & Tomasello, 2005).

This and other studies (e.g., Onishi & Baillargeon, 2005) provide strong evidence that children begin to read the intentions of other people in the first year of life. By the end of the second year, perhaps even by 13 to 15 months of age, children become very good at reading intentions (Baillargeon, Li, Ng, & Yuan, 2009). In other words, even though preschool-age children tend to view the world based only on their own perspectives, they have the cognitive ability to understand others’ perspectives. And as infants and children acquire theory of mind, they develop the ability to think in increasingly sophisticated ways.

FIGURE 4.17 variations in Attachment style This chart breaks down what percentage

of children (of parents who have a secure

attachment style) show a secure, an

avoidant, or an ambivalent attachment style.

Attachment styles of infants whose parents are securely attached (percentage)

Avoidant infants

Ambivalent infants

Secure infants

0 605040302010 70

TRY IT YOURsELF: Development of Self-Recognition

To determine whether an infant you know has developed

the cognitive ability to recognize himself, gently place a

red dot about the size of a dime on his nose, using red

lipstick or face paint. Then, carefully, hold the infant in

front of a mirror. If the infant can recognize himself, he

will stare at the dot, touch it, or try to remove it. If the

infant cannot recognize himself, he will not notice the red

dot as unusual, so he won’t focus on it at all. If the infant

does not show self-recognition, do this task again every

few weeks. At a certain point, the infant will suddenly

show this cognitive ability.

130 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

pIAGET’s THEORY OF COGNITIvE DEvELOpMENT As the movie Boyhood opens, the mother of 6-year-old Mason is scolding him. He ruined his teacher’s pencil sharpener by putting rocks in it. Mason’s mother can’t understand what he was thinking. “What were you going to do with sharpened rocks?” she asks. “I was trying to make arrowheads for my rock collection,” he explains. If you have ever spent time with a child, you may recognize this explanation as an example of “child logic.” This kind of logic makes no sense to an adult, but to a child it makes perfect sense.

The developmental psychologist Jean Piaget investigated how children’s think- ing changes as they develop (Figure 4.18). By exploring the mental abilities of his own three children and many others, Piaget discovered that children’s minds truly do work in a different way than those of adults.

Specifically, Piaget proposed that we change how we think as we form new schemas, or ways of thinking about how the world works. Piaget described two ways that we develop a schema, which are shown in the Learning Tip. During assimilation, we place a new experience into an existing schema, which is a mental representation about that information. During accommodation, we create a new schema, or dramatically alter an existing one to include new infor- mation that otherwise would not fit into the schema. For example, a 2-year-old might see a butterfly for the first time and shout, “Bird!” After all, a butterfly has wings and flies just like birds. But the toddler’s parent says, “No, honey, that’s a butterfly! See, it doesn’t have a beak!” Now the child must accommodate this new information about beaks into the existing schema about birds. And he must also accommodate by creating a new schema about flying animals. The constant repe- tition of assimilation and accommodation allows a child to develop increasingly complex schemas over time. These schemas allow the child to think in more- sophisticated ways. Piaget’s research became the basis for his influential theory that children go through four progressively complex stages of cognitive develop- ment, which are summarized in Figure 4.19.

assimilation The process we use to incorporate new

information into existing schemas (mental

representations).

accommodation The process we use to create new schemas

(mental representations) or drastically

alter existing ones to incorporate new

information that otherwise would not fit.

LEARNING TIp: Assimilation and Accommodation

Use this graphic to help you understand the difference between the two ways that thinking develops as

described by Jean piaget.

(a) (c)

Correctly add information to schema of “BIRDS”:

Assimilation Accommodation

• They have wings. • They fly.

“Is it a bird?” “No, it’s not a bird.”

(b)

Accommodation Update schema of “BIRDS” to include new information: • They have wings.

• They have beaks. • They fly.

Create new schema of “FLYING ANIMALS”: • They have wings. • They fly. • But they don’t have beaks.

“It’s another type of flying animal.”

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 131

sENsORIMOTOR sTAGE: BIRTH TO 2 YEARs Accord- ing to Piaget, children from birth until about age 2 are in the sensorimotor stage of cognitive development. During  this period, they acquire information primarily through their senses and motor exploration. For example, they first learn reflexively, by sucking on a nipple, grasping a finger, or seeing a face.

As infants begin to control their motor movements, they develop their first schemas. These mental representations contain information about actions that can be performed on certain kinds of objects. For instance, the sucking reflex lets the infant realize she can suck other things, such as a bottle, a finger, a toy, or a blanket. Piaget described sucking other objects as an example of assimilation to the schema of suck- ing. But sucking a toy or a blanket does not result in the same experience as the reflexive sucking of a nipple. The difference between these experiences leads the child to alter the sucking

sensorimotor stage The first stage in piaget’s theory of

cognitive development; during this stage,

infants acquire information about the

world through their senses and motor

skills.

FIGURE 4.19 piaget’s Four stages of Cognitive Development piaget described how children’s thinking

abilities are characterized across four

stages of cognitive development.

Stage Characteristics

Sensorimotor (birth–2 years)

• Starts to mentally represent information acquired through the senses and motor

exploration.

• Begins to act intentionally—for example, pulls a string to set a mobile in motion or shakes a rattle to make a noise.

• Achieves object permanence by realizing that things continue to exist even when no longer present to the senses.

1

Preoperational (2–7 years)

• Learns to use language and to represent objects by images and words.

• Thinking is egocentric, where the child has difficulty taking the viewpoint of others.

• Can think intuitively, not logically.

• Classifies objects by a single feature—for example, groups blocks by color regardless of their shape.

2

Concrete operational (7–12 years)

• Can think logically about concrete objects and events.

• Achieves conservation of number, volume, mass, and weight.

• Flexibly classifies objects by several features and can order them in a series along a single

dimension, such as size.

3

Formal operational (12 years and up)

• Can think logically about abstract propositions and test hypotheses systematically.

• Becomes concerned with hypothetical issues, the future, and ideological

problems.

4

FIGURE 4.18 Jean piaget piaget’s work with young children revealed that thinking

becomes more sophisticated as we progress through

several stages of cognitive development.

132 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

schema to include new experiences and information. For example, while sucking a blanket, she may create a new schema that includes using less force than sucking on a bottle. She uses the process of accommodation to create this new schema.

According to Piaget, one important cognitive concept developed in this stage is object permanence—the understanding that an object continues to exist even when it is hidden from view. Piaget noted that until 9 months of age, most infants will not search for objects they have seen being hidden under a blanket. At around 9 months, they will look for the hidden object by picking up the blanket. A child’s full comprehension of object permanence was, for Piaget, one key accomplish- ment of the sensorimotor period.

pREOpERATIONAL sTAGE: 2 TO 7 YEARs According to Piaget, children from about 2 to 7 years of age can begin to think about objects not in their imme- diate view. They have developed mental representations of objects that are not in view. During this preoperational stage, children begin to think symboli- cally. For example, they can pretend that a stick is a sword or a wand. However, Piaget believed that children at this stage cannot think operationally—in other words, they cannot imagine the logical outcomes of performing certain actions on certain objects. Instead, they use intuitive reasoning based on superficial appearances.

For instance, children at this stage have no understanding of the law of conser- vation. This law states that even if the appearance of a substance changes in one dimension, the properties of that substance remain unchanged. For example, if you pour a short, wide glass of water into a tall, narrow glass, the amount of water does not change. But if you ask children in the preoperational stage which glass contains more, they will pick the tall, narrow glass because the water is at a higher level. The children will make this error even when they have seen someone pour the same amount of water into each glass or when they pour the liquid themselves. They cannot understand that it is the narrower diameter of the taller glass that makes the water level higher (Figure 4.20).

The lack of conservation skills is thought to be due to a key cognitive limitation of the preoperational stage: centration. This limitation occurs when a child cannot think about more than one aspect of a problem at a time. The child “centers” on only one detail of the problem, so his ability to think logically is limited.

Another cognitive characteristic of the preoperational period is egocentrism. Preoperational thinkers generally view the world through their own experi- ences. They can understand how others feel, and they are able to care about others, but their thought processes tend to revolve around their own perspec- tives. For example, a 2-year-old may play hide-and-seek by placing a box over her head, believing that if she cannot see other people, other people cannot see her (Figure 4.21). Instead of viewing this egocentric thinking as a limitation, modern scholars agree with Piaget that such “immature” skills prepare children to take special note of their immediate surroundings and learn as much as they can about how their own minds and bodies interact with the world. A clear egocen- tric focus prevents them from trying to expand their schemas too much before they understand how they think about and understand their own experiences (Bjorklund, 2007).

CONCRETE OpERATIONAL sTAGE: 7 TO 12 YEARs At about 7 years of age, according to Piaget, children enter the concrete operational stage. They remain in this stage until adolescence. Piaget believed that humans do not develop logic until they begin to think about and understand operations. A classic operation is

FIGURE 4.20 Conservation Task Based on volume In the preoperational stage, according to

piaget, children reason intuitively, not

logically. As a result, these children cannot

yet understand the concept of conservation,

which is shown here in a task focusing on

the volume of a liquid.

A young child understands that two identical short glasses contain the same amount of water.

1

Here, the child observes the water from one of the short glasses poured into the tall glass.

2

When asked which one contains more water, the child will point to the taller glass, even though the amount of water is the same as in the short glass.

3

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 133

an action that can be undone: A light can be turned on and off, a stick can be moved across the table and then moved back, and so on. According to Piaget, when chil- dren are able to understand that an action is reversible, they can begin to under- stand concepts such as conservation. Children in this stage are not fooled by superficial transformations, such as how the volume of liquid can look different in glasses of varying size. Instead, they can reason logically about problems.

Although using operations is the beginning of logical thinking, Piaget believed that children at this stage reason only about concrete things. That is, they reason about objects they can act on in the world. They are not yet able to reason abstractly, or hypothetically, about what might be possible. Because they cannot do opera- tions “in their heads,” children in first, second, and third grades often use objects to do math. They use their fingers to add and subtract, and they group objects, such as tokens, to multiply and divide. By using concrete information, children in this stage can think in much more logical ways than children in the preoperational stage. However, according to Piaget, they cannot truly engage in sophisticated abstract thinking until they reach adolescence.

FORMAL OpERATIONAL sTAGE: 12 YEARs TO ADULTHOOD  Piaget’s final stage of cognitive development is the formal operational stage. Here, people can reason in sophisticated, abstract ways. Formal operations involve critical thinking, characterized by the ability to form a hypothesis about something and test the hypothesis through logic. Critical thinking also involves using infor- mation to systematically find answers to problems. To study this ability, Piaget gave teenagers and younger children four flasks of colorless liquid and one flask of colored liquid. He then explained that the colored liquid could be obtained by combining two of the colorless liquids. Adolescents, he found, systematically try different combinations to obtain the correct result, whereas younger children just randomly combine liquids. Adolescents are also able to consider abstract notions and think about many viewpoints at once. Lastly, this kind of thinking is characterized by an ability to envision the future and predict the consequences of certain actions.

NEW WAYs OF THINKING ABOUT pIAGET’s THEORY Piaget’s theory revo- lutionized the understanding of cognitive development. And he was right about many things. For example, infants do learn about the world through sensorimotor exploration. Also, people do move from intuitive, illogical thinking to a more logical understanding of the world. However, modern research has revealed that we have to consider Piaget’s theory more flexibly.

For example, we now know that Piaget underestimated the ages at which certain skills develop. When contem- porary researchers use age-appropriate methods they find that object permanence develops in the first few months of life, rather than at  8 or 9 months of age, as Piaget thought (Baillargeon, 1987). In his various studies, Piaget may have confused

preoperational stage The second stage in piaget’s theory of

cognitive development; during this stage,

children think symbolically about objects,

but they reason based on intuition and

superficial appearances rather than logic.

concrete operational stage The third stage in piaget’s theory of

cognitive development; during this

stage, children begin to think about and

understand logical operations, and they

are no longer fooled by appearances.

formal operational stage The final stage in piaget’s theory of

cognitive development; during this stage,

people can think abstractly, and they can

formulate and test hypotheses through

logic.

FIGURE 4.21 Egocentrism This toddler is playing hide and seek with her

mother. Because the toddler’s head is in the box

and she cannot see the mother, she believes that

the mother also cannot see her. She is definitely

in the preoperational stage.

134 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

infants’ cognitive abilities with their physical capabilities. Because of this, he may have underestimated the age at which some thinking skills develop. For example, infants may not be able to grasp a hidden object, but they may still understand that it exists.

In addition, psychologists now think of cognitive development in terms of trends rather than strict stages. People gradually shift from one or more ways of thinking to other ways of thinking, so they may exhibit skills from different stages simultaneously (Figure 4.22). For example, while a certain child might not under- stand the conservation of volume (see Figure 4.20), she may be able to perform a conservation task based on number (Figure 4.23). This view of cognitive develop- ment is consistent with our understanding of brain development. Cognitive devel-

opment may not necessarily follow strict and uniform stages, because different areas of the brain are responsible for different skills (Bidell & Fischer, 1995; Case, 1992; Fischer, 1980).

Language Develops in an Orderly Way Recall that 19-year-old Brooke Greenberg, whose physical and mental development stopped when she was a toddler, could communicate only by making infant-like sounds. The ability to speak in sentences develops as the brain changes and as cognitive abilities become more sophisticated. It is important to recognize that as children develop social skills, they also improve their language abilities. Thanks to language, we can live in complex societies where our ability to communicate helps us learn the history, rules, and values of our culture. Language also helps us communi- cate across cultures and learn much more than other animals can. How do we develop our remarkable ability to use language?

FROM ZERO TO 60,000 Language is a system of using sounds and symbols according to grammatical rules. It can be viewed as a hierarchical structure. Sentences can be broken down into smaller units, called phrases, and phrases can be broken down into words (Figure 4.24a). Each word consists of one or  more morphemes (the smallest units that have meaning, including suffixes and prefixes). Each morpheme consists of one or more phonemes ( basic sounds; Figure 4.24b). For example, the word asked has two morphemes (“ask” and “ed”) and four phonemes (the sounds you make when you say the word: /a /s/k /t /). Syntax is the system of rules about how words are combined into phrases and how phrases are combined to make sentences. For example, English syntax dictates that we say Stephanie asked for some milk, not Stephanie some milk for asked.

FIGURE 4.22 Trends in Cognitive Development modern interpretations view piaget’s theory

in terms of trends, not rigid stages. Children

shift gradually in their thinking over a wider

range of ages than previously thought, and

they can demonstrate thinking skills of more

than one stage at a time.

2Newborn 61/2 111/2

FIGURE 4.23 Conservation Task Based on Number When a task is performed in an

age-appropriate manner, children are able

to show conservation of number much

earlier than they can show conservation of

volume (see figure 4.20).

A 4-year-old is shown two rows of marbles. Each row has the same number of marbles, but one row is spread out. When asked which row has more marbles, the 4-year-old says the longer row. In this case, he fails to show conservation of number.

1

However, when asked to count the marbles in each row, the 4-year-old counts correctly and states that the two rows have the same number of marbles. Now he does show conservation of number.

2

HOW DO INfANTS AND CHILDREN DEvELOp OvER TImE? ■ 135

Infants are born ready to learn language. In fact, the language or languages that mothers speak during pregnancy influence the listening preferences of newborns. For instance, Canadian newborns whose moth- ers spoke only English during pregnancy showed a strong preference for sentences in English as compared with sentences in Tagalog, a major language of the Philippines. Newborns of mothers who spoke both Taga- log and English during pregnancy paid attention to both languages (Byers- Heinlein, Burns, & Werker, 2010). Further, up to 6 months of age, a baby can discriminate all the speech sounds that occur in all languages, even if the sounds do not occur in the language spoken in the baby’s home (Kuhl, 2006; Kuhl et al., 2006; Kuhl, Tsao, & Liu, 2003).

From hearing sounds immediately after birth and then learning the sounds of their own languages, babies develop the ability to speak. With- out working very hard at it, humans appear to go from babbling as babies to employing a full vocabulary of about 60,000 words as adults. Learning to speak follows a distinct path. During the first months of life, newborns’ actions—crying, fussing, eating, and breathing—generate all their sounds. In other words, babies’ first verbal sounds are cries, gurgles, grunts, and breaths. From 3 to 5 months, they begin to coo and laugh. From 5 to 7 months, they begin babbling, using consonants and vowels. From 7 to 8 months, they babble in syllables (ba-ba-ba, dee-dee-dee).

By the end of their first year, infants around the world are usually saying their first words. These first words typically combine phonemes into morphemes to label items in their environment (kitty, milk), simple action words (go, up, sit), quantifiers (all gone! more!), qualities or adjectives (hot), socially interactive words (bye, hello, yes, no), and even internal states (boo-boo after being hurt; Pinker, 1984). Thus even very young children use words to perform a wide range of communicative functions. They name, comment, and request.

By about 18 to 24 months, children’s vocabularies start to grow rapidly. They put words together and form basic sentences of roughly two words. Though these mini-sentences are missing some words, they have what is known as syntax. Typi- cally, the word order indicates what has happened or should happen: For example, “Throw ball. All gone” translates as I threw the ball, and now it’s gone. The psychol- ogist Roger Brown called these utterances telegraphic speech because the chil- dren speak as if they are sending a telegram. They put together bare-bones words according to correct syntax (Brown, 1973).

As children use language in increasingly sophisticated ways, they sometimes overapply regular grammar rules. This tendency is called overregularization. For example, when children learn that adding -ed makes a verb past tense, they add –ed to every verb, even verbs that do not follow that rule. Thus they may say “runned” or “holded” even though they may have said “ran” or “held” at a younger age. This trend usually lasts through the early elementary school years, when chil- dren begin to master irregular forms of words. Such overregularizations reflect an important aspect of language acquisition: Children are not simply repeating what they have heard others say. After all, they most likely have not heard anyone say “runned.” Instead, these errors occur because children recognize patterns in spoken grammar and then apply the patterns to new sentences they never heard before (Marcus, 1996; Marcus et al., 1992). Of course, as children gain experience using language with other people, they usually learn to correct these mistakes. By about age 6, children use language nearly as well as most adults. Their vocabulary will continue to grow throughout their lives.

FIGURE 4.24 Organization of Language (a) Language is organized hierarchically. Sentences and phrases are created from

words, words are created from

morphemes, and morphemes are created

from phonemes. (b) In learning to read, these children are combining phonemes

into morphemes.

babbling Intentional vocalization, often by an infant,

that does not have a specific meaning.

telegraphic speech The tendency for toddlers to speak by

combining basic words in a logical syntax,

but not a complete sentence, to convey a

wealth of meaning.

overregularization The tendency for young children to

incorrectly use a regular grammar rule

where they should use an exception to

the rule.

136 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

■ Infants are born with innate reflexes, but through experiences we learn to

move and process sensory information.

■ forming strong attachments with caregivers helps infants develop appropriate

social interactions and emotion regulation.

■ Infants’ and children’s cognitive abilities become more advanced with time

and experience as they move through four stages of cognitive development.

■ Children develop language skills starting with the production of phonemes

and eventually moving to speaking full sentences.

4.2 CHECKpOINT: How Do Infants and Children Develop Over Time?

Daniel came home from work and was looking forward to

spending some time with his 12-month-old daughter, Amy.

He was enjoying watching her change every day. And it was

particularly interesting to connect all the information about

developmental psychology to what Amy was doing. A few

months ago, Daniel had tested her motor reflexes. And a few

weeks ago he had investigated whether she was showing any

stranger anxiety. I won’t try that one again, Daniel thought. Boy, did she scream when I introduced her to the new sitter! Just last week, Daniel realized that Amy had acquired the skill

of object permanence when she crawled to get a ball that

had rolled out of sight under the couch. But although Amy

was babbling a lot, she wasn’t speaking many words yet.

Daniel wondered whether he could do anything to help Amy

learn to speak. He remembered having seen lots of advertise-

ments for media that claimed to teach babies how to talk.

Daniel thought to himself, I have a little time before Mom brings Amy home. I’ll hop on the Web and see what I can find.

Daniel entered some search terms and immediately found

information that seemed helpful. One product was a DvD from

a well-respected company, which said it “introduces little ones

to words and sign language.” Next to the picture of the DvD,

Daniel saw testimonials from parents describing the positive

effects of the product on their kids. Daniel thought about this

information. Even the name of the product, “Baby Einstein,” suggests there is something genius-inducing about it!

As Daniel continued his search, he found one study stating

that 76 out of the top 100 best-selling baby DvDs on Amazon

made similar types of educational claims. Another article

stated that educational DvDs geared toward infants earn

about $500 million in sales every year. OK, so the companies advertise these products as educational. And they sell a lot of them. But do these products really work? Or are parents wasting their money? Or worse still, might these products adversely affect children? I need some scientific evidence!

Daniel decided to dig deeper. This time, he used Google

Scholar to explore whether products like these would help

kids learn to talk. Soon enough, he found believable informa-

tion from scientific journals, not product advertisements. One

study of 1,000 infants aged 7–16 months revealed that kids who

watched the educational DvDs had poorer ability to under- stand spoken language than those kids who did not watch the

DvDs. In fact, these infants knew about 6–8 fewer words for

every hour that they watched the DvDs. Another study found

that children between 12 and 15 months of age who watched

the Baby Wordsworth DvD five times over two weeks showed

no effect on either ability to understand or speak language.

It seems pretty clear that the educational claims these DVDs make are just for marketing purposes. It looks like they won’t help Amy learn to talk. I wonder what will help? In his searches for journal articles, Daniel repeatedly saw that the

amount of time an infant was read to did predict language

abilities. In addition, when caregivers actively read with chil-

dren, pointing out pictures and words and discussing the

story, these social interactions seemed to better support

development of language skills than watching “educational”

DvDs. That decides it for me! We are going to read books together every day for at least 20 minutes. And I will talk with Amy about the pictures on the pages and point out the various words to her. That way, I can do my part to help her learn to talk. And it will be fun to spend that time with her!

QUEsTION What was the DVD advertisement trying to get Daniel and

other parents to believe? What evidence did Daniel find to

refute these claims? What do you think is the most reason-

able conclusion about the educational DVDs?

BEING A CRITICAL CONsUMER: Can My Baby Learn to Talk by Watching Educational Media?

HOW DO ADOLESCENTS DEvELOp? ■ 137

4.3 How Do Adolescents Develop?

puberty The physical changes in the body that are

a part of sexual development.

secondary sex characteristics physical changes during puberty that

are not directly related to reproduction

but that indicate the differences between

the sexes

Do you remember when you began to go through adolescence? We all go through this stage, unless there is some problem with our physical development (as was the case with Brooke Greenberg, discussed in the chapter opener). This period starts at the end of childhood, about age 11 through 14, and lasts until about age 18 or 21. Your adolescent body was changing in major ways, growing larger and sometimes doing things beyond your control. Your emotions may have seemed uncontrolla- ble as well. And you suddenly may have felt wildly attracted to people you never thought about before.

As children approach adolescence, all aspects of the self are changing. Physical changes occur, socio-emotional changes emerge as part of evolving relationships with parents and peers, and cognitive changes arise as part of the potential emer- gence of critical and analytical thinking. Taken together, changes in these three domains lay the foundation for the development of a sense of personal identity.

Adolescents Develop Physically Physically, adolescence is characterized by the onset of sexual maturity and the abil- ity to reproduce. puberty, a roughly two-year developmental period, marks the begin- ning of adolescence. The first signs of puberty typically begin at about age 8 for girls and at about age 9 or 10 for boys. Most girls complete pubertal development by age 16 (Ge, Natsuaki, Neiderhiser, & Reiss, 2007; Herman-Giddens, Wang, & Koch, 2001; Sun et al., 2005) and boys finish by the age of 18 (Lee, 1980).

pUBERTY When you were around 10 or 12 years old, did you seem to grow overnight? This adolescent growth spurt—a rapid, hormonally driven increase in height and weight—is an obvious dividing line between childhood and puberty. During puberty, hormone levels increase throughout the body, stimulating many physical changes that allow us to develop into sexually mature adults.

The first changes that occur are the secondary sex characteristics (Figure 4.25). Boys and girls start to experience greater growth of body hair, first as darker and thicker hair on the legs, then under the arms, then as pubic hair (Marshall & Tanner), then in other places. Boys’ muscle mass increases, their voices deepen, and their jaws become more angular. Girls lose baby fat on their

LEARNING GOALs READING ACTIvITIEs

a. Remember the key terms related to adolescent

development.

List all of the boldface words and write down their

definitions.

b. Understand the physical changes in puberty.

Summarize the changes in secondary and primary sex

characteristics and when they occur in boys and girls, using

your own words.

c. Apply socio-emotional aspects of development to your

own adolescence.

provide a description of the development of your sense of

identity, including your ethnic identity and how you relate

to family and friends.

d. Analyze one aspect of cognitive development, a moral

dilemma, in your own life.

Describe three ways you could reason morally about a

dilemma in your life based on Kohlberg’s theory.

138 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

bellies as their waists become more defined, and they also develop fat deposits on the hips and breasts (Lee, 1980). You will learn more about puberty, and how these changes affect the sexual desires of adolescents, in Chapter 10.

Puberty also brings the development of the primary sex characteristics. That is, the male and female external genitals and internal sex organs mature, menstru- ation begins in girls, and sperm develops in boys. These physical changes result in adolescents’ becoming sexually mature and able to reproduce.

Puberty may seem to be purely physical, but it is affected by environment. For example, a girl who lives in a stressful environment or has insecure attachments to caregivers is likely to begin menstruating earlier than a girl in a peaceful, secure environment (Wierson, Long, & Forehand, 1993). This finding suggests that a girl’s body responds to stress as a threat. Because the body feels threatened, it speeds up the ability to reproduce in order to continue the girl’s gene pool. Thus environmental forces trigger hormonal changes, which send the girl into puberty (Belsky, Houts, & Fearon, 2010). Because boys do not have an easily identifiable pubertal event like menstruation in girls, we know less about the effects of envi- ronment on puberty in boys. Boys and girls experience similar changes in brain development during adolescence, however, so researchers are able to identify a few key characteristics of the teenage brain.

BRAIN CHANGEs DURING ADOLEsCENCE While teenagers are experienc- ing pubertal changes, their brains also are in an important phase of reorgani- zation. Synaptic connections are being refined, and gray matter is increasing. However, the frontal cortex of the brain is not fully developed until the early 20s. An adolescent’s limbic system—the motivational and emotional center of the brain—tends to be more active than the frontal cortex. As a result, although teenagers are able to think critically, they often have a difficult time doing so. Instead, they are more likely to act irrationally and engage in risky behaviors than adults are (Blakemore  & Choudhury, 2006; Casey, Jones, & Somerville, 2011). Because teen agers have the ability to understand the consequences of their actions, it is important to help them learn about behavioral consequences. If parents, teachers, community members, and other adults are supportive and provide the proper guidance and discipline, adolescents will know that people who care about them will help them develop good decision-making skills (Stein- berg & Sheffield, 2001).

Adolescents Develop Socially and Emotionally

Adolescents may be physically able to reproduce, but they are still developing socially and emotionally. Typically, they are focused less on family at this age and more on themselves as they develop friendships and try to answer the question “Who am I?” The search for who each of us is as a person is at the core of socio- emotional development for every adolescent (Figure 4.26).

How we define ourselves is influenced by many factors, including the culture in which we are raised, our gender, and our beliefs about personal characteristics such as race, sex, and age. The quest for identity is an important challenge during development, especially in Western cultures, where individuality is valued. As adolescents seek to understand how they fit into the world and to imagine what

(a)

Childhood Early adolescence (During puberty)

Childhood Early adolescence (During puberty)

(b)

FIGURE 4.25 physical Development During Adolescence These graphics show how adolescents

develop secondary sex characteristics

during puberty that change them from

looking like children to looking like

adults. (a) Boys develop darker and thicker body hair on the legs, in the

armpits, in the pubic area, and on the

face and chest. They grow taller and

gain muscle mass. Their jaw becomes

more angular. (b) Girls develop darker and thicker body hair on the legs, in

the armpits, and in the pubic area. They

become taller, they grow breasts, their

waists become more defined, and they

gain more fat on their hips.

primary sex characteristics physical development during puberty that

results in sexually mature reproductive

organs and genitals.

HOW DO ADOLESCENTS DEvELOp? ■ 139

kind of person they will become later in life, they build on the preceding developmental stages.

DEvELOpING A UNIQUE IDENTITY The psychologist Erik Erikson proposed a theory of human development based on the psychological challenges we face at different ages in our lives and how these chal- lenges affect our social relationships. Erikson thought of psychosocial development as having eight stages, starting from an infant’s first year of life to old age (Table 4.1). Because it recognizes the importance of the entire life span, Erikson’s theory has been extremely influential in developmental psychology. However, a theory is only as good as the evidence that supports it, and few researchers have tested Erikson’s theory directly.

Erikson thought of each life stage as having a major developmental “crisis”—a challenge to be confronted. All of these crises are present throughout life, but each takes on special importance at a particular stage. Although each crisis provides an opportunity for psychologi- cal development, a lack of progress may impair further psychosocial development (Erikson, 1980). However, if the crisis is successfully resolved, the challenge provides skills and attitudes that the individual will need to face the next challenge. Successful resolution of the early challenges depends on the supportive nature of the child’s environ- ment as well as the child’s active search for information about what he is skilled at. According to Erikson’s theory, adolescents face perhaps the most fundamental challenge: how to develop an adult identity. This crisis of identity versus role confusion includes addressing questions about who we are. These questions concern our ethnic and cultural identity, how we relate to family and friends, and other individual characteristics.

ETHNIC IDENTITY Culture shapes much of who we are as we develop a full sense of identity during adolescence. Culture also determines whether each person’s identity will be accepted or rejected. In a multiracial country such as the United States, questions of racial or ethnic identity can be complicated. Forming an ethnic identity can be a particular challenge for adolescents of color.

Children entering middle childhood have some awareness of their ethnic iden- tities. That is, they know the labels and attributes that the dominant culture applies to their ethnic group. During middle childhood and adolescence, children in ethnic minority groups often engage in additional processes aimed at ethnic identity formation (Phinney, 1990). The factors that influence these processes vary widely among individuals and groups.

For instance, a child of Mexican immigrants may struggle to live successfully in both a traditional Mexican household and a Westernized American neighbor- hood and school. The child may have to serve as a “cultural broker” for his family, perhaps translating materials sent home from school, calling government agencies or insurance companies, and handling more adultlike responsibilities than other children the same age. In helping the family adjust to the stress of life as immi- grants in a foreign country, the child may feel additional pressures, but he may also develop important skills in communication, negotiation, and caregiving (Cooper, Denner, & Lopez, 1999). And by successfully negotiating these tasks, a child can develop a bicultural identity. That is, the child strongly identifies with two cultures

FIGURE 4.26 Development of Identity in a Teen Who are you? What do you love? How do you see

yourself? All adolescents face such questions as

part of their socio-emotional development.

identity versus role confusion fifth stage of Erikson’s theory of

psychosocial development, where

adolescents face the challenge of

figuring out who they are.

140 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

and seamlessly combines a sense of identity with both groups (Vargas-Reighley, 2005). A child in this situation who develops a bicultural identity is likely to be happier, better adjusted, and have fewer problems in adult social and economic roles.

pARENTs AND pEERs If you were asked for one adjective that best describes “teenager,” what would you say? The odds are high that it would be rebellious. Recall from the opening story that even 19-year-old Brooke Greenberg, who was frozen in the body of a 19-month-old toddler, displayed this rebellious nature by refusing to do things she did not like. Throughout the world, it seems that as adolescents develop their own identities, they come into more conflict with their parents.

For most families, this conflict leads only to minor annoyances. It can actually help adolescents develop important skills, including negotiation, critical think- ing, communication, and empathy (Holmbeck, 1996). According to Erikson’s theory, negotiating a pathway to a stable identity requires breaking away from childhood beliefs by questioning and challenging parental and societal ideas

sTAGE AGE MAJOR psYCHOsOCIAL CRIsIs sUCCEssFUL REsOLUTION OF CRIsIs

1. Infancy 0–2 Trust versus mistrust Children learn that the world is safe and that people are loving and reliable.

2. Toddler 2–3 Autonomy versus shame and doubt

Encouraged to explore the environment, children gain feelings of independence and positive self-esteem.

3. preschool 4–6 Initiative versus guilt

Children develop a sense of purpose by taking on responsibilities, but they also develop the capacity to feel guilty for misdeeds.

4. Childhood 7–12 Industry versus inferiority By working successfully with others and assessing how others view them, children learn to feel competent.

5. Adolescence 13–19 Identity versus role confusion By exploring different social roles, adolescents develop a sense of identity.

6. Young adulthood 20s Intimacy versus isolation Young adults gain the ability to commit to long-term relationships.

7. Middle adulthood 30s to 50s Generativity versus stagnation Adults gain a sense that they are leaving behind a positive legacy and caring for future generations.

8. Old age 60s and beyond Integrity versus despair Older adults feel a sense of satisfaction that they have lived a good life and developed wisdom.

TABLE 4.1

Erikson’s Eight stages of psychosocial Development

SOURCE: Erikson (1959).

HOW DO ADOLESCENTS DEvELOp? ■ 141

(Erikson, 1968). But even though adolescents and their parents may disagree and sometimes argue, across cultures parents have a great deal of direct influence on their children’s individual behaviors, values, and sense of autonomy (Feldman & Rosenthal, 1991). Parents also indirectly affect social development by influ- encing children’s choices about friends (Brown, Mounts, Lamborn, & Steinberg, 1993; Cairns & Cairns, 1994).

Peers play a crucial role in identity development. Peer groups are created when teenagers form friendships with others who have similar values and world- views (Figure 4.27a). Observers outside the peer groups tend to place teenagers who dress or act a certain way into groupings, called cliques (Figure 4.27b). The observers often see members of cliques as virtually interchangeable, and commu- nity members may respond to all youths from that group in similar ways (Urberg, Degirmencioglue, Tolson, & Halliday- Scher, 1995). The teenagers, however, often see themselves as unique and individual, or as connected to a small subset of close friends, not just as members of a certain clique. The friendships created in these peer groups provide an important sense of belonging, social support, and acceptance.

Adolescents Develop Cognitively Teenagers may be rebellious, but they still need to make good decisions based on the rules of the culture they live in. Moral choices, large ones and small ones alike, affect other people. Ideally, the ability to consider questions about morality devel- ops during childhood and continues into adulthood.

MORAL REAsONING AND MORAL EMOTIONs Moral development is the way people learn to decide between behaviors with competing social outcomes. In other words, when is it acceptable to take an action that may harm others or that may break implicit or explicit social contracts? Theorists typically divide morality into moral reasoning, which depends on cognitive processes, and moral

(a) (b)

FIGURE 4.27 peers and Cliques (a) Adolescents develop strong friendships with peers who share similar interests and values. (b) Outside observers might tend to place the young men in this peer group into a single clique, “punks,” and would tend to react to all of them in similar ways. Each adolescent, however, might

view himself as an individual.

142 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

emotions. Moral emotions, such as embarrassment and shame, are considered self-conscious emotions. They are called self-conscious because they involve how people think about themselves. For example, the emotional experience of sadness might become the self-conscious emotional experience of shame when it is your- self you feel sad about. It is important to note, however, that moral reasoning is affected by moral emotions (Moll & de Oliveira-Souza, 2007). The development of moral emotions is vital to acting morally.

Psychologists who study the cognitive processes of moral behavior have focused largely on Lawrence Kohlberg ’s stage theory. Kohlberg (1984) tested moral-reasoning skills by asking people to respond to hypothetical situations in which someone was faced with a moral dilemma. For example, should a person steal a drug to save his dying wife because he could not afford the drug? Kohlberg was most concerned with the reasons people provided for their answers, not just the answers themselves. He devised a theory of moral judgment that involved three main levels of moral reasoning.

At the preconventional level, people solve the moral dilemma in terms of self-interest. For example, a person at this level might say, “He should steal the drug because he could get away with it.” Or “He should not steal the drug because he will be punished.” At the conventional level, people’s responses conform to rules of law and order or focus on others’ approval or disapproval. For example, a person at this level might say, “He should take the drug because everyone will think he is a bad person if he lets his wife die.” Or “He should not take the drug because that’s against the law.” At the postconventional level, the highest level of moral reasoning, people’s responses center on complex reasoning. This reason- ing concerns abstract principles that transcend laws and social expectations. For example, a person at this level might say, “He should steal the drug. Sometimes people have to break the law if the law is unjust.” Or “He should not steal the drug. If people always did what they wanted, it would be anarchy. Society would break down.” Thus Kohlberg believed advanced moral reasoning to include considering the greater good for all people and giving less thought to personal wishes or fear of punishment. You can learn more about Kohlberg ’s stages of moral reasoning in the Learning Tip on p. 144.

Not all psychologists agree with moral-reasoning theories such as Kohlberg ’s. Critics fault these theories for emphasizing only the cognitive aspects of morality and neglecting emotional issues that influence moral judgments, such as shame, pride, or embarrassment. They believe that moral actions, such as helping others in need, are influenced more by emotions than by cognitive processes.

Finally, not everyone progresses through the stages of moral development at the same rate or in the same order. How can a parent, guardian, or other author- ity figure help guide a younger person’s moral development? According to the research, there is great value in showing the general consequence of a specific behavior. Saying “You made Chris cry. It’s not nice to hit, because it hurts people” is more effective than saying simply “Don’t hit people.” Such explanation promotes children’s sympathetic attitudes, appropriate feelings of guilt, and awareness of other people’s feelings. The resulting attitudes, feelings, and awareness then influence the children’s moral reasoning and behavioral choices, which also help instill moral values that guide behavior throughout life. This cycle of moral devel- opment can be readily seen in cases of bullying, as described in Using Psychology in Your Life.

preconventional level Earliest level of moral development; at this

level, self-interest and event outcomes

determine what is moral.

conventional level middle level of moral development; at this

level, strict adherence to societal laws and

the approval of others determine what is

moral.

postconventional level Highest level of moral development; at this

level, decisions about morality depend on

abstract principles and the value of all life.

Have you ever been the victim of bullying? Have you seen children or

adolescents being bullied? Have you ever bullied someone? Bullying is

when someone repeatedly uses physical power or control over another

person, behaving aggressively in a way that is unwanted (Espelage and

Holt, 2012). There are many types of bullying:

• physical: physical contact that hurts a person—for example, hitting,

kicking, punching, taking away an item and destroying it—and physi-

cal intimidation, such as threatening someone and frightening him

enough to make him do what the bully wants.

• verbal: name-calling, making offensive remarks, or joking about a

person’s appearance, religion, gender, ethnicity, sexual orientation;

and verbal intimidation.

• Social: spreading rumors or stories about someone, excluding some-

one from a group on purpose, or making fun of someone by pointing

out her differences.

• Cyber: sending aggressive, threatening, and/or intimidating messages,

pictures, or information using social media, computers (e-mail and

instant messages), or cell phones (text messaging and voicemail).

Bullying is a complex behavior with many contributing factors.

However, experts tend to agree that bullies might not strongly feel the

moral emotions of guilt and shame (Hymel, Rocke-Henderson, & Bonanno,

2005). Bullies also often show increased moral disengagement, such as

indifference or pride, when explaining their behavior and more-positive

attitudes about using bullying to respond to difficult social situations.

Because bullying tends to get people what they want and society tradi-

tionally turns a blind eye to it, bullying goes on. However, both kids who

are bullied and those who bully others can have serious, lasting problems.

So what can you do? Here are three steps adults should take when they

see an act of bullying occurring among children and adolescents:

1. stop the bullying on the spot: Intervene in a calm and respectful manner, separate the children, make sure they are safe, and get any

needed medical help.

2. Find out what happened: Once you have separated the kids, get all of their views on what happened. Seek evidence from other people who

witnessed the act. Do not jump to conclusions or place blame.

3. support the kids involved: Listen to the person being bullied, assure him that it’s not his fault, and work to resolve the bullying situation. Also

work with the person doing the bullying to help him realize his behav-

ior is wrong, understand why he bullies, and take steps to reduce the

behavior.

By modeling good moral reasoning and good moral behavior, and

reducing the rewards associated with bullying, you can help children

and adolescents develop appropriate moral values. Even other kids

can learn to be more than bystanders and help reduce bullying. for

more information on how to respond to bullying and prevent it, visit

www.stopbullying.gov.

Bullying

UsING psYCHOLOGY

IN YOUR LIFE:

■ During puberty, both males and females undergo physical changes, including

development of secondary and primary sex characteristics and changes in

the brain.

■ Adolescence is the time when teens develop socio-emotionally by trying to

resolve the psychosocial conflict of identity versus role confusion.

■ The establishment of gender identity reflects the interaction of nature

(biological factors of sex and hormones) and nurture (gender socialization).

■ During adolescence, cognitive development leads to more-sophisticated

moral reasoning.

4.3 CHECKpOINT: How Do Adolescents Develop?

This Learning Tip will help you understand Kohlberg’s three levels of moral reasoning by applying them to a situation you

may be familiar with: adhering to the speed limit (or not!). Remember: Kohlberg’s levels are not based on whether a person

chooses to do or not do something. They are based on the reasoning behind the person’s decision.

sTAGE AND AGE OF MORAL DEvELOpMENT

MORAL REAsONING ExAMpLE OF A pERsON UsING THIs REAsONING

preconventional level: often seen in young children, but can be seen in other people too.

Reasoning about a moral dilemma is based on self-interest, such as getting personal gains, making a good deal, and/or avoiding personal losses.

“I’m driving the speed limit because my parents said that if I don’t get any speeding tickets for a year they will buy me a car for college.”

“I have to drive faster than the speed limit. my boss will dock my pay if I’m late for work!”

Conventional level: often seen in older children, most adolescents, and some adults.

Reasoning about a moral dilemma is based on expectations, such as conforming to social norms to get approval from others and/or obeying legal rules.

“Everyone is going faster than the speed limit on this highway! I am just keeping up with the speed of the other drivers.”

“I’m driving only 20 mph because we are in a school zone. That’s the legal speed limit for driving near schools!”

postconventional level: seen in only a small proportion of adolescents and adults.

Reasoning about a moral dilemma is based on “higher” principles, including people’s individual rights in a society and/or abstract ideas about justice and equality.

“my wife was about to give birth. She was screaming, and I was afraid for her life and the life of our baby. I was driving too fast because surely people’s lives are more important than laws about the speed limit!”

“It’s unjust that some groups of people are targeted for getting speeding fines more than other groups, so I am not going to obey the speed limit.”

LEARNING TIp: Applying Kohlberg ’s Three Levels of Moral Development

SOURCE: Kohlberg, 1984.

144 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

HOW DO WE DEvELOp IN ADULTHOOD? ■ 145

4.4 How Do We Develop in Adulthood?

We’ve all seen adults who still act like adolescents. Watching them can be funny or embarrassing. But what does it really mean to be an adult? For many years, devel- opmental psychologists focused on childhood and adolescence, as if most impor- tant aspects of development occurred by age 20 and then people did not change anymore. In recent decades, researchers working in a wide range of fields have demonstrated that throughout adulthood, important changes occur physically, socio-emotionally, and cognitively. Therefore, many contemporary psychologists consider development from the perspective of the entire life span. Their goal is to understand how mental activity and social relations change over the entire course of life. Adulthood, then, becomes an important topic for study. Beginning at the end of adolescence, lasting through old age and concluding with death, adulthood makes up most of our life span. The developmental changes during adulthood vary from stage to stage.

Our Bodies Change in Adulthood Our bodies are ready to reproduce when we reach our teens. We peak in fitness during our 20s. So, evolutionarily speaking, a 40-year-old is quite old. In fact, for most of our history, humans lived only a few decades. As recently as the beginning of the twentieth century, the average life expectancy in the United States was only 47 years. However, since 1900, through modern medicine and improvements in hygiene and in food availability, the average life expectancy in the United States has increased by more than 30 years (Organization for Economic Cooperation and Development, 2013).

EARLY TO MIDDLE ADULTHOOD It’s the prime of life! Really? Between the ages of 20 and 40, we actually experience a steady decline in muscle mass, bone density, eyesight, and hearing (Shephard, 1997). As we approach middle age, we start to notice that we can no longer drink as much alcohol, eat as much junk food, or get by on as little sleep as we could in our 20s. That “middle-age spread,” the accumulation of fat around the belly, becomes harder and harder to work off. As a result, nutrition, exercise, and a healthy lifestyle are important in early adulthood. In addition, exercise during early adulthood is associated

LEARNING GOALs READING ACTIvITIEs

a. Remember the key terms about adult development. List all of the boldface words and write down their

definitions.

b. Understand physical development as we age. Describe in your own words how people change physically

across the two main stages of adulthood.

c. Evaluate socio-emotional changes in adulthood.

Critique why socio-emotional changes in adulthood can

make this one of the happiest and most satisfying times of

life.

d. Apply the cognitive aspects of development in

adulthood.

provide a description of how the mental abilities of

someone you know have changed as the person has aged.

146 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

with improved health and a longer life (Figure 4.28). Study participants who walked briskly 15 minutes per day ( Wen et al., 2011) or ran 5–10 minutes per day (Lee et  al., 2014) lived an average of 3 years longer than participants who did not exercise.

TRANsITION TO OLD AGE In Western societies, people are living much longer, and the number of people over age 85 is growing dramatically. Indeed, it is becoming common- place for people to live beyond 100. By 2030, more than 1 in 5 Americans will be over age 65, and these older people will be ethnically diverse, well educated, and physically fit (National Research Council, 2006). With this “graying ” of the population in Western societies, much greater research attention has been paid to the lives of people over age 60.

Our view of the elderly is changing a lot as the baby boom generation ages. Many older adults work productively well past their 70s. For instance, nearly 40 percent of U.S. federal judges are over 65 (Markon, 2001). Popular-music stars such as Madonna, Bruce Springsteen, and the Rolling Stones are still performing well into

their 50s, 60s, and beyond, certainly defying common stereotypes of older people (Figure 4.29).

Nevertheless, the body and mind start deteriorating more rapidly at about age 50. The cosmetics and plastic surgery industries are booming as we try to cover up superficial physical changes such as the graying of hair and the wrinkling of skin. But some of the most serious changes affect the brain, whose fron- tal lobes shrink proportionally more than other brain regions (Cowell et al., 1994). Scientists once believed that cognitive problems such as confusion and memory loss were a normal, inevitable part of aging. They now recognize that most older adults remain alert; they just do everything a bit more slowly.

Adults Develop Lifelong Social and Emotional Bonds Despite its sometimes rocky road, adolescence can be an exciting and gratify- ing time. Ideally, during this period we meet new friends, learn new ideas, and consolidate our emerging sense of identity. Successfully meeting the challenges of adolescence prepares us to face the challenges of adulthood. This new set of challenges is based on the need to find meaning in our lives.

psYCHOsOCIAL CHALLENGEs Think back to Erikson’s theory that we develop psychosocially through eight life stages (see Table 4.1). According to Erikson, successful adult development includes having intimate relationships with friends and partners, giving back to society, and viewing life in a generally positive light, even through the many ups and downs or tragedies.

Young adulthood is the time of Erikson’s sixth stage. The psychosocial chal- lenge during this stage, intimacy versus isolation, is about forming and main- taining committed friendships and romantic relationships. The key idea is that as young adults we are finding people to share life with in intimate ways. We are moving outward from ourselves rather than being socially isolated.

FIGURE 4.29 Changing views of the Elderly The Rolling Stones, now in their 60s and

early 70s, are still making music after

50 years.

FIGURE 4.28 staying Healthy in Adulthood Exercising in early adulthood—for example,

by walking quickly or running—helps

keep us physically fit and psychologically

healthy. It also helps us live longer.

intimacy versus isolation Sixth stage of Erikson’s theory of

psychosocial development, where young

adults face the challenge of forming

committed long-term friendships and

romances.

generativity versus stagnation Seventh stage of Erikson’s theory of

psychosocial development, where

middle-aged adults face the challenge of

leaving behind a positive legacy and caring

for future generations.

integrity versus despair Eighth stage of Erikson’s theory of

psychosocial development, where

older adults face the challenge of feeling

satisfied that they have lived a good life

and developed wisdom.

HOW DO WE DEvELOp IN ADULTHOOD? ■ 147

Erikson emphasized the Western value of merging with others while not losing our own sense of identity. For Erikson, building a strong sense of identity in adolescence is crucial for being able to form truly intimate relationships with others in adulthood. He argued that if a person has no sense of self, it is more difficult to engage in honest, open, emotionally close relationships with others (Erikson, 1980).

Erikson’s seventh-stage challenge, generativity versus stagnation, takes place during middle age. This stage focuses on making improvements for future generations. Caring for children, being productive in a career, having regard for others, and being concerned about the future are positive psychosocial actions of this stage. If our children turned out well, our career was satisfying, and we contributed to our community, we are more likely to leave middle age with a sense of generativity, or leaving a positive legacy. The opposite of generativ- ity, stagnation, includes a feeling that life is going nowhere or that we are very materialistic and self-centered. Contemporary research indicates that people who are high in generativity have a more positive outlook on life (McAdams & Olson, 2010).

In old age, we reach Erikson’s last challenge, integrity versus despair. Integ- rity refers to a sense of honesty about ourselves and a feeling that our lives have been well lived, so that facing death is neither scary nor depressing. For Erikson, the psychosocial challenge of late adulthood involves how we view our life, not whether that life was easy or trauma free. The crisis at this stage can be triggered by events that highlight the mortal nature of human life, such as the death of a spouse or close friend. The crisis also can be triggered by changing social and occupational roles, such as retirement. Resolving the final challenge allows us to come to terms with the reality of death. If we have many regrets, lack close relationships, or are angry about getting older, we may resolve the psychosocial conflict with a sense of despair instead of integrity. Although Erikson’s theory paints a rather mixed view of old age, a great deal of evidence suggests that older adults are much more satisfied with their lives than was traditionally believed. One recent study of older adults between ages 65 and 92 found that life satisfac- tion generally increased over an 8-year period (Gana, Bailly, Saada, Joulain, & Alaphilippe, 2013).

MARRIAGE In adulthood, people devote a great deal of effort to having satis- fying relationships. One way to do this is through marriage. Around the world, the vast majority of people marry at some point in their lives or form some type of permanent bond with a relationship partner (Figure 4.30). As marriage equality increases across the United States, more same-sex couples are also marrying. However, the percentage of people who marry is declining slowly in most industrialized countries, and people today marry later in life than did those in the past (Grossman, 2005).

Research shows that marriage has psychological benefits for the couple. For example, married people generally live longer than people who were never married, were divorced, or were widowed (Waite, 1995). When people’s income rises (as by combining two salaries through marriage), they are able to live in safer neighbor- hoods, have better health care, eat better, and so on. Compared with those who are unmarried, married people typically experience greater happiness and joy and are at less risk for psychological disorders such as depression (Robles & Kiecolt-Glaser, 2003). These benefits also exist for same-sex married people (Herek, 2006).

The benefits of marriage are more significant for men than for women, however. Studies suggest that men may benefit from marriage because their wives make

Grison, Heatherton & Gazzaniga: Psychology in Your Life Figure# 04.30 Date: 05/20/13 Dragonfly Media Group

(a)

(b)

(c)

FIGURE 4.30 Marriage Across cultures, marriage remains a

building block of society. If the statistics

hold true, (a) this Sami couple in Norway, (b) this Amhara couple in Ethiopia, and (c) this Hani couple in China will report being happy in their marriages.

148 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

sure they smoke less, eat more healthily, and go to the doctor. Women serve as the primary social support for their husbands. Married men report higher sexual and relationship satisfaction than do cohabitating and single men; but across these same groups, women report no difference. Married women report more emotional satisfaction, however, than cohabitating or single women do. You will read more about the sexual lives of older adults in Chapter 10.

Still, marriage is not a cure-all. Unhappily married people are at greater risk for poor health and even mortality than happily married people. In general, people who are in unhappy marriages, are separated, or are divorced have many physical and psychological struggles, ranging from depression to physical illness to violent behavior (Carrère, Buehlman, Gottman, Coan, & Ruckstuhl, 2000). Note, though, that these studies are largely correlational. It could be that happy, well-adjusted people are more likely to get married and not that marriage causes good outcomes for people. Or perhaps unhappy, negative people have both health problems and strained marriages.

The good news is that according to national surveys, at any given time the vast majority of married people report satisfaction with their marriages. Those report- ing the most satisfaction tend to have sufficient economic resources, share decision making, and together hold the view that marriage should be a lifelong commitment (Amato, Johnson, Booth, & Rogers, 2003). Having a successful marriage contrib- utes to a sense of generativity in middle adulthood, as does having children.

HAvING CHILDREN The birth of a first child is a profound event for most couples. In fact, this arrival changes their lives in almost every respect. Seeing a baby’s first social smile, watching the first few tentative steps, and hearing a child say her first words are powerful rewards for parents. Being a parent is central to the identity of many adults. They often become immersed in their children’s lives, making sure their children have playmates, exposing them to new experiences, and seeking ways to make them happy and healthy.

Research shows that children can strain a couple’s relationship, however, espe- cially when time and money are tight. Consistently, couples with children, espe- cially those with adolescent children, report less marital satisfaction than those who are childless (Belsky, 1990; Cowan & Cowan, 1988). Most couples feel their love will be enough to make the birth of a baby a blissful time. These couples often receive a rude awakening when they are sleep deprived, agitated, and less than skilled at caring for their new bundle of joy, especially during the first months (Cowan & Cowan, 1988).

Contemporary researchers are trying to find ways to prepare parents for parent- hood so the transition does not put such a strain on the relationship. For example, Philip and Carolyn Cowan, a married couple who are also marriage researchers, have found that many couples do not discuss roles and responsibilities before they have a child. This failure to communicate leads to misunderstandings and feelings of resentment after the child’s birth. The Cowans recommend that couples have serious and detailed conversations about all aspects of their lives and how they will approach each task after the baby is born.

Partners who report their early married life as chaotic or negative are more likely to find that having a baby does not bring them closer together or solve their problems. Instead, raising the child increases the existing strain. Teaching newly- weds or young partners how to communicate and understand each other’s needs may prevent divorce, and it may also allow the couple to enjoy parenting when their children are young as well as when they grow older and the children leave home (Shapiro, Gottman, & Carrère, 2000; Figure 4.31).

HOW DO WE DEvELOp IN ADULTHOOD? ■ 149

FINDING MEANING IN LATER LIFE People of all ages want to find meaning in life. But meaning often becomes a preoccupation for the elderly. As people grow older, they perceive time to be limited, so they adjust their priorities to emphasize emotionally meaningful events, experiences, and goals (Carstensen, 1995; Fung & Carstensen, 2004). For instance, they may choose to spend more time with a smaller group of close friends and avoid new people. They may spend an increasing amount of time reflecting on their lives and sharing memories with family members and friends. As they look back on their lives, older adults report more positive emotions than negative ones (Pasupathi & Carstensen, 2003).

The message here is that older adults want to savor their final years by putting their time and effort into meaningful and rewarding experiences. To the extent that they consider their time well spent, older adults are satisfied and can live their final years gracefully. This result is especially likely if throughout their lives they have worked hard to maintain their physical health, their social ties, and their cognitive capacities.

The Mental Abilities of Adults Begin to Decline Yes, the baby boom generation is filling a large percentage of judgeships and providing us with some still-favorite entertainers. That generation has also given rise to the common phrase a senior moment—the inability to remember something we knew a moment before. In that moment, we know we’re just not as sharp as we once were.

Although we may not notice until later adulthood, our cognitive abilities actu- ally begin declining much earlier in our lives. It’s difficult to pinpoint exactly what causes the decline. The frontal lobes, which play an important role in certain types of memory and many other cognitive skills, typically shrink as people grow older. One of the most consistent and identifiable cognitive changes is a slowing of mental processing speed. As early as the mid-20s, it takes us longer to process a sensory input and react with a motor response, and the response time becomes greater as we age (Era, Jokela, & Heikkinen, 1986).

Some of the observed decline may result from sensory-perceptual changes that occur with age. For instance, our sensitivity to visual contrast decreases, so

FIGURE 4.31 Having Children Is Both a Joy and a strain on a Couple’s Relationship Having children is a key part of socio-emotional development for most adults because it

provides an amazing opportunity to experience the joy of a parent-child emotional bond.

(a) But having children can also create conflict within a couple’s relationship. (b) Such conflict has to be managed in a positive way to ensure success for the family.

(a) (b)

150 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

activities such as climbing stairs or driving at night may become more difficult and more dangerous. Sensitivity to sound also decreases with age, especially the ability to tune out background noise. This change may make older people seem confused or forgetful when they simply are not able to hear well enough. And unfortunately, aging also affects memory and intelligence.

INTELLIGENCE, LEARNING, AND MEMORY For 7 years, the Seattle Longitudinal Study tracked participants between the ages of 25 and 81 to address questions of intelligence during aging (Schaie, 1990). By testing cognitive abilities such as verbal and mathematical skills, the researchers found that intellectual decline does not occur until people are in their 60s or 70s. Further, they found that people who were healthy and stayed mentally active demonstrated less decline.

Older adults do take longer to learn new information. Still, once they learn it, they use that information as efficiently as young adults do. Moreover, older adults have accumulated a great deal of knowledge over their lives and therefore tend to know more than younger adults. Perhaps for this reason, we often view older adults as wise.

It is well-known that older people tend to have difficulty with memory tasks that require juggling multiple pieces of information at the same time. Tasks that call for them to do several things at once, such as driving while listening to the radio, also prove difficult. Although memory and the speed of processing may decline, the continued ability to learn new information may offset those losses in terms of daily functioning. In addition, research shows that older adults can improve their memories if they do aerobic exercise (Erickson et al., 2011; Prakash, Voss, Erickson, & Kramer, 2015). This benefit seems to come because vigorous exercise that increases the heart rate increases the size of the hippo- campus (Figure 4.32). And as you may recall from Chapter 2, the hippocampus is important for creating memories, so these findings make sense.

DEMENTIA Older adults who experience a dramatic loss in mental ability may be experiencing dementia. This brain condition causes gradual decline in think- ing, memory, and behavior. Dementia has many causes, including excessive alcohol intake and HIV. But for older adults, the major causes are Alzheimer’s disease and small strokes that affect the brain’s blood supply. After age 70, the risk of demen- tia increases with each year of life. Approximately 3 percent to 5 percent of people will develop Alzheimer’s disease by age 70 to 75, and 6.5 percent will develop the disease after age 85 (Kawas, Gray, Brookmeyer, Fozard, & Zonderman, 2000).

dementia Severe impairment in intellectual capacity

and personality, often due to damage to

the brain.

FIGURE 4.32 Aerobic Exercise May Improve Memory Abilities Even as We Age participants in this study engaged in

either vigorous aerobic exercise or gentle

stretching activities. A year later, the

results showed an increase in the size

of the left and right hippocampi and

improvements in memory, but only in

the group who did aerobic exercise.

5.2

H ip

p o c a m

p u s s

iz e

(v o lu

m e i n m

m 3 )

LEFT HIPPOCAMPUS

Baseline 6 months 1 year

Aerobic exercise

Stretching

5.1

5.0

4.9

4.8

4.7

4.6

Aerobic exercise

Stretching

5.2

H ip

p o c a m

p u s s

iz e

(v o lu

m e i n m

m 3 )

RIGHT HIPPOCAMPUS

Baseline 6 months 1 year

5.1

5.0

4.9

4.8

4.7

4.6

HOW DO WE DEvELOp IN ADULTHOOD? ■ 151

The initial symptoms of Alzheimer’s are typically minor memory impairments, but the disease eventually progresses to more serious diffi- culties, such as forgetting daily routines (Figure 4.33). It takes about 4 years for people to progress from mild cognitive impairment to a diagnosis of Alzheimer’s (Kawas et al., 2000). Eventually, the person loses all mental capacities, including memory and language. Many people with Alzheim- er’s also experience profound personality changes. While we do not know the exact cause of Alzheimer’s, some people seem to have a genetic predis- position to its development.

Besides a genetic predisposition to Alzheimer’s (Corder et al., 1993), there may be genetic predispositions to other kinds of dementia. That picture may seem grim, but a predisposition is not a hopeless case, because environment also has an impact. Decades of research show that challeng- ing one’s brain by learning new tasks, working puzzles, reading, remaining socially active, and maintaining physical exercise at least 3 days per week is associated with a significantly lower risk of dementia (Fratiglioni, Paillard-Borg, & Winblad, 2004; Larson et al., 2006). As you age, playing an active role in your own develop- ment may help make adulthood transitions nonthreatening, even deeply reward- ing experiences (Figure 4.34).

WELL-BEING IN OLDER ADULTs Despite the physical, social, and emotional challenges of aging, most older adults are healthy and happy. Except for dementia, older adults have fewer mental health problems, including depression, than younger adults (Jorm, 2000). Indeed, some individuals thrive in old age, especially those with adequate financial resources and good health (Crosnoe & Elder, 2002). Most older adults report being just as satisfied with life, if not more so, as younger adults are (Mroczek & Kolarz, 1998). As noted earlier, one study found that life satisfaction increased for older adults over an 8-year period.

Thus this chapter ends where it began, with a reminder that all aspects of human development result from a complex interplay of influences. These influences include genes, hormones, family, social ties, culture, and each individual’s motivations and actions. We all play active roles in our own development. We are not passively absorbing our envi- ronments, nor are we solely ruled by our genes. How we experience each phase of the life span depends on our own perceptions, the social support we receive, and the choreographed dance between nature and nurture.

FIGURE 4.33 Impairments from Alzheimer’s Disease A woman helps her husband, who has

Alzheimer’s disease. This brain condition,

which is the major cause of dementia,

occurs in the elderly.

■ physical changes are inevitable, especially after the age of 50. Keeping in

shape during early adulthood has positive physical and psychological effects.

■ In adulthood, we experience several psychosocial conflicts, which we resolve

by developing long-term relationships, having children and satisfying careers,

and feeling satisfied.

■ Cognitive abilities decline as we grow old. physical exercise can improve

memory. Only some older adults experience dementia.

■ Despite the declines of older adulthood, many elderly people thrive, reporting

this period as the happiest time of life.

4.4 CHECKpOINT: How Do We Develop in Adulthood?

FIGURE 4.34 Maintaining Health and Happiness most older adults report being very happy.

Engaging in activities that stimulate the

brain (doing crossword puzzles) and

the body (swimming and walking) is

associated with staying healthy and happy

for as long as possible.

152 ■ CHApTER 4 DEvELOpmENT ACROSS THE LIfE SpAN

a. Remember the key terms related to prenatal development.

b. Understand the three prenatal periods.

c. Apply information about teratogens and their effects during prenatal development.

d. Analyze how biology and environment affect prenatal development.

B IG

P IC

T U

R È 4.1 How Do We

Develop in

the Womb?

a. Remember the key terms about how infants and children develop.

b. Understand motor and sensory development in an infant.

c. Apply socio-emotional aspects of child development to real life.

d. Understand the four stages of cognitive development in children.

e. Analyze the three stages of language development in childhood.

4.2 How Do Infants

and Children

Develop Over

Time?

a. Remember the key terms about adult development.

b. Understand physical development as we age.

c. Evaluate socio-emotional changes in adulthood.

d. Apply the cognitive aspects of development in adulthood.

4.4 How Do We

Develop in

Adulthood?

a. Remember the key terms related to adolescent development.

b. Understand the physical changes in puberty.

c. Apply socio-emotional aspects of development to your own adolescence.

d. Analyze one aspect of cognitive development, a moral dilemma, in your own life.

4.3 How Do Adolescents

Develop?

BIG QUESTION LEARNING GOALS

BIG pICTURE ■ 153

KEY TERMS CHECKPOINT

■ Developmental psychology explores growth in terms of how both nature (inborn genetics and biological traits) and nurture (environment) affect human development.

■ Human development occurs in three interacting domains: physical, socio-emotional, and cognitive.

■ prenatal physical development occurs in three periods: germinal, embryonic, and fetal.

■ Teratogens are environmental substances that negatively affect prenatal development. They may have long-term effects on physical, cognitive, and socio-emotional development.

developmental psychology germinal period embryonic period fetal period teratogens

■ Infants are born with innate reflexes, but through experiences we learn to move and process sensory information.

■ forming strong attachments with caregivers helps infants develop appropriate social interactions and emotion regulation.

■ Infants’ and children’s cognitive abilities become more advanced with time and experience as they move through four stages of cognitive development.

■ Children develop language skills starting with the production of phonemes and eventually moving to speaking full sentences.

maturation secure attachment avoidant attachment ambivalent attachment assimilation accommodation sensorimotor stage preoperational stage concrete operational stage formal operational stage babbling telegraphic speech overregularization

■ During puberty, both males and females undergo physical changes, including development of secondary and primary sex characteristics and changes in the brain.

■ Adolescence is the time when teens develop socio-emotionally by trying to resolve the psychosocial conflict of identity versus role confusion.

■ The establishment of gender identity reflects the interaction of nature (biological factors of sex

and hormones) and nurture (gender socialization).

■ During adolescence, cognitive development leads to more-sophisticated moral reasoning.

puberty secondary sex characteristics primary sex characteristics identity versus role confusion preconventional level conventional level postconventional level

■ physical changes are inevitable, especially after the age of 50. Keeping in shape during early adulthood has positive physical and psychological effects.

■ In adulthood, we experience several psychosocial conflicts, which we resolve by developing long-term relationships, having children and satisfying careers, and feeling satisfied.

■ Cognitive abilities decline as we grow old. physical exercise can improve memory. Only some older adults experience dementia.

■ Despite the declines of older adulthood, many elderly people thrive, reporting this period as the happiest time of life.

intimacy versus isolation generativity versus stagnation integrity versus despair dementia

For a self-quiz on this chapter, go to the back of the book and find Appendix B: Quizzes.

BIG QUESTIONS 5.1 How Do Sensation and Perception Affect Us?

5.2  How Do We See?

5.3  How Do We Hear?

5.4 How Can We Taste and Smell?

5.5  How Do We Feel Touch and Pain?

WHAT DO YOU EXPERIENCE when you see the color red or eat chocolate? If you are like most

people, you experience red as a visual phenomenon. You may associate this color with stoplights or

stop signs. You experience eating chocolate as a sweet taste. You may associate this taste with plea-

sure. But not everyone would agree with these descriptions.

William hates driving because, to him, the sight of road signs tastes like a gross mixture of pista-

chio ice cream and earwax (McNeil, 2006). For Michael, any personal name has a specific taste—for

example, the name “John” tastes like corn bread (Simner et al., 2006). Another person experiences

each day of the week, or month of the year, as a particular color—Monday is red, Tuesday is indigo,

December is yellow, and so on (Ramachandran & Hubbard, 2003). Other people experience colors as

smells, sights as sounds, or sounds as colors and shapes.

5 Sensation and Perception

155155

156 ■ CHAPTER 5 SENSATION AND PERcEPTION

1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 Figure 5.1 Synesthesia Shows Unusual Relationships Between Sensation and Perception In synesthesia, sensory input in one form is experienced in another form. In color-number

synesthesia, each number is seen as a particular color.

This condition, where people receive sensory input in one form and expe-

rience it in another form, is called synesthesia. If you have never experienced

synesthesia, it is almost impossible to imagine. However, the condition is not

that rare. Estimates of the percentage of the population that report these

cross-sensory experiences range from 1 in 2,000 to 1 in 200. And reports of

people with synesthesia date as far back as ancient Greece (Ferry, 2002).

But modern psychological research is revealing how people have these

unique perceptual experiences.

The explanation is in the brain. For example, during brain scans taken

of people with color-number synesthesia who looked at black numbers

on a white background, researchers found neural activity in the brain area

responsible for color vision. control participants without synesthesia did

not show activity in this brain area when they looked at the same numbers

(Ramachandran, 2003). Each person who has synesthesia experiences it in a

very consistent way. For example, a certain number always appears to be one

particular color (Figure 5.1). color-number synesthesia may occur because

the brain area involved in seeing colors is near the brain area involved in

understanding numbers. Specifically, these two brain areas may some-

how be connected, or one area of the brain might have adopted another

area’s role.

Research into synesthesia can give us insight into how people process

sensory input as well as how our brains help us perceive sensory information

in our own unique ways. The perceptual system is stunningly intelligent in its

ability to guide us around. For example, right this minute your brain is making

millions of calculations to produce a coherent experience of your environment.

Neurons inside your brain do not directly experience the outside world. Instead,

they communicate with other neurons inside your brain. Your conscious experi-

ence of the world emerges from this communication. And this all happens in

milliseconds.

HOW DO SENSATION AND PERcEPTION AFFEcT US? ■ 157

5.1 How Do Sensation and Perception Affect Us?

Imagine you take half a grapefruit out of the refrigerator and dig into it with a spoon. Some juice splashes out of the fruit and hits your nose and mouth. What do your senses tell you? You smell some strong fragrance. You feel something cold on your skin. You taste something sharp on your tongue. So far, your experi- ence consists of raw sensation. Your sensory systems have detected features of the juice.

Sensation is the detection of physical stimuli from the world around us and the sending of that information to the brain. Physical stimuli can be light waves, sound waves, food molecules, odor molecules, temperature changes, or pressure changes on the skin. In sensing the splash of the grapefruit juice, you are sensing food molecules, odor molecules, slight temperature changes, and slight pressure changes.

Perception is the brain’s further processing of sensory information. This processing results in our conscious experience of the world. The essence of perception is interpreting sensation. That is, our perceptual systems (as opposed to our sensory systems) translate sensation into information that is meaningful and useful. In the above example, perception is interpretation of the sensory stimuli of cold droplets, a strong smell, and a sharp taste as qualities of grapefruit.

But even when people experience the exact same sensory input (sensation), they experience that input differently (perception). If you like grapefruit, you might experience this splash as at least partly pleasant. If you dislike grape- fruit—suppose your father has insisted that you eat it—you might experience the splash as totally unpleasant. The Try It Yourself exercise on p. 158 will help you begin to understand the differences between sensation and perception.

Our Senses Detect Physical Stimuli, and Our Brains Process Perception Suppose you are driving, and the traffic signal changes from red to green. Believe it or not, there is actually no red or green color in the signal or in the light you see. Instead, your eyes and brain enable you to see the redness or greenness of the light. Objects in the physical world don’t actually have color. Each object reflects light waves of particular lengths. Our visual systems interpret those waves as different colors.

sensation The sense organs’ detection of external

physical stimulus and the transmission of

information about this stimulus to the brain.

perception The processing, organization, and

interpretation of sensory signals in the

brain; these processes result in an internal

neural representation of the physical

stimulus.

LEARNINg gOALS READINg ACTIvITIES

a. Remember the key terms about sensation and

perception.

List all of the boldface words and write down their

definitions.

b. Apply the four steps from sensation to perception to

your life.

Using a sensory input you have experienced, describe the

four steps from sensation to perception.

c. Understand absolute threshold and difference threshold. Use your own words to compare absolute threshold and

difference threshold.

d. Apply signal detection theory to real life. Use signal detection theory to explain the four ways new

parents could respond to their baby’s crying.

158 ■ CHAPTER 5 SENSATION AND PERcEPTION

So how do light waves get changed into information that the brain can process? Special cells in our eyes respond to these different wavelengths and change that physical signal into information that the brain can interpret. If you are driving and your brain receives information about a green traffic light, your brain most likely will interpret that light as meaning “Go.”

FROM SENSATION TO PERCEPTION To understand more clearly both sensation and perception, imagine that you drive up to a traffic signal as it turns green. The green light is actually the physical stimulus in the form of light waves (Figure 5.2, Step 1). That stimulus is detected by specialized cells called sensory receptors. The receptors’ detection of the stimulus is sensation (see Figure 5.2, Step 2).

In a process called transduction, the sensory receptors change the stimu- lus input to signals that the brain can understand (see Figure 5.2, Step 3). In some cases, such as taste, transduction directly results in neurons’ firing action

Figure 5.2 From Sensation to Perception Here is a summary of the four steps in the process of changing sensory input into a personal

experience. The example is for sensation and perception of vision, but the steps in general also

apply to hearing, taste, smell, and touch. However, information about smell is not processed

through the thalamus.

sensory receptors Sensory organs that detect physical

stimulation from the external world and

change that stimulation into information

that can be processed by the brain.

transduction A process by which sensory receptors

change physical stimuli into signals that

are eventually sent to the brain.

TRY IT YOURSELF: Sensation and Perception If you and your friends look at the same car, will you all agree on the color? check

it out with this example:

1. Look only at the picture of the car. Decide what color the car is. Then look at the

color bar and decide which color sample is most similar to how you see the color

of the car. Write down both of your answers.

2. Now ask a few other people to do the things in step 1.

3. Most likely, some people have labeled the car color the same way you did. Some

people have chosen different labels. However, the label a person chooses for the

color doesn’t tell us what that person has actually perceived.

4. But even people who labeled the car the same way you did might have chosen

a different color sample from the one that you chose. This result suggests you

had different perceptions of the same color.

What does this demonstration show? The sensory input, the sensation, is the same

for people. Yet each person has a unique perception of that input. Taken together,

sensation and perception make up all of our individual experiences with the world.

21 3 4 5 6 7 8

Physical stimulus: A traf�c light turns green. Light waves are the physical stimulus.

1 Sensation: The light waves are detected by sensory receptors in the driver’s eyes.

2 Transduction: The sensory receptors translate the physical stimulus into signals. Those signals will become neural signals.

3 Perception: The neural signals travel along nerve �bers to the thalamus. Then cortical areas in the brain process the signals and construct a representation of a green light. The brain interprets the light as indicating “Start driving!”

4

Start driving!

Sensory receptors

Neural signals

Thalamus

Cortical areas for vision

HOW DO SENSATION AND PERcEPTION AFFEcT US? ■ 159

potentials (to review the firing of action potentials, see Chapter 2). For vision, more processing must happen before the information is coded as action poten- tials. When the brain does process the action potentials, you will interpret them as green light. You will also register the meaning of that traffic signal as “Go.” This further processing of the information following transduction is perception (see Figure 5.2, Step 4).

This example demonstrates the general processes of sensation and percep- tion. However, the details are slightly different for each sense. In this chapter, you will learn about the four steps of sensation and perception for each major sensory system. In each case, a physical stimulus is detected, specialized sensory recep- tors transduce the stimulus information, and neurons fire action potentials. These action potentials are the sensory information that is sent to specific regions of the brain for interpretation (Figure 5.3).

The sum of this activity, across all of your senses, is your huge range of percep- tions. And your perceptions add up to your experience of the world. If you get splashed with grapefruit juice or see the color of a traffic light, your sensations and perceptions enable you to interpret the information and respond appropriately. For example, you decide the juice is delicious or you accelerate the car.

There Must Be a Certain Amount of a Stimulus for Us to Detect It Stop reading for a moment and listen. What do you hear? Perhaps voices in the next room or music down the hall. But can you hear the buzzing of the fly that you see on the window across the room? How much physical stimulus is required for our sense organs to detect sensory information? How much change in the physical stimulus is required before we notice that change in the sensory information?

THRESHOLD TO DETECT SENSORY INFORMATION An enormous amount of physical stimulation from the world around you reaches your sensory recep- tors. Even so, you do not notice much of it. Physical stimulation has to go beyond some level before you experience a sensation. The absolute threshold is the

Somatosensory cortex (touch)

Parietal lobe

Frontal lobe

Olfactory cortex (smell)

Temporal lobe Primary auditory cortex (hearing)

Occipital lobe

Primary visual cortex (vision)

Gustatory cortex (taste)

Figure 5.3 The Brain’s Primary Sensory Areas Except for smell, all sensory input is first

processed through the thalamus. Then

inputs are sent to cortical regions that

process information about vision, hearing,

taste, smell, and touch.

absolute threshold The smallest amount of physical

stimulation required to detect a sensory

input half of the time it is present.

160 ■ CHAPTER 5 SENSATION AND PERcEPTION

minimum amount of physical stimuli required before you detect the sensory input (Figure 5.4). You can also think of the absolute threshold as the smallest amount of a stimulus a person can detect half of the time the stimulus is present. For instance, how loudly must someone in the next room whisper for you to hear it? In this case, the absolute threshold is the quietest whisper you could hear half the time. Table 5.1 lists some approximate minimum levels of physical stimuli that are required to detect sensory input for each sense.

A difference threshold is the smallest difference that you can notice between two pieces of sensory input. In other words, it is the minimum amount of change in the physical stimulus required to detect a difference between one sensory expe- rience and another. Suppose your friend is watching a television show. You are reading and not paying attention to what’s on the screen. If a commercial comes on that is louder than the show, you might look up, noticing that something has changed. In this case, the difference threshold is the minimum change in volume required for you to detect a difference.

difference threshold The minimum difference in physical

stimulation required to detect a difference

between sensory inputs.

Table 5.1

Absolute Threshold to Detect Input for Each Sense

SENSE MINIMUM SENSORY INPUT REqUIRED FOR DETECTION

Taste 1 teaspoon of sugar in 2 gallons of water

Smell 1 drop of perfume diffused into the entire volume of six rooms

Touch A fly’s wing falling on your cheek from a distance of 0.04 inch

Hearing The tick of a clock at 20 feet under quiet conditions

vision A candle flame 30 miles away on a dark, clear night

SOURcE: Galanter (1962).

Figure 5.4 Absolute Threshold (a) can this man detect a soft sound, such as a whisper? (b) This graph shows the relationship between the intensity of stimulus input and a person’s ability to correctly detect the input. The

absolute threshold is the point of stimulus intensity that a person can correctly detect half the time.

(a) (b)

Correct detection (percentage)

50

100

Stimulus intensity

Low High 0

Absolute threshold is the level of stimulus intensity at which a person correctly detects a stimulus 50 percent of the time.

HOW DO SENSATION AND PERcEPTION AFFEcT US? ■ 161

Have you ever been in a car and

had to keep turning up the music

so that you could hear it above

the wind or road noise? You may

have turned it up a bit but heard

no difference in loudness. So

you turned it up a bit more. And

maybe even louder still, until you

could finally hear the music. This

example illustrates the difference

threshold. You could not detect

small changes in loudness because

the music was already so loud. But

later on, when you entered the car

under quieter conditions, you were

probably shocked at how loud the

music really was.

HAS IT HAPPENED

TO YOU?

Difference Threshold

The difference threshold increases as the stimulus becomes more intense. Say you pick up a 1-ounce jar of spice and a 2-ounce jar of spice. You will easily detect the difference of 1 ounce. Now pick up a 5-pound package of flour and a package that weighs 5 pounds and 1 ounce. The same difference of 1 ounce between these two will be harder to detect, maybe even impossible to detect.

The principle at work here is called Weber’s law. This law is based on the work of the nineteenth-century psychologist Ernst Weber. The law states that the just- noticeable difference between two sensory inputs is based on a proportion of the original sensory input rather than on a fixed amount of difference. What does that mean? Assume the overall stimulus input is less intense (as in the case of the 1-ounce container). A specific change in input (say 1 ounce) can easily be detected by a person. But now assume the original stimulus is more intense (as in the case of the 5-pound package). That same change in input (1 ounce) is much harder to detect. Weber’s law may sound complex. But as shown in Has It Happened to You?, we experience difference thresholds all the time.

SIgNAL DETECTION THEORY The concept of an absolute threshold means that either you saw something or you did not. Your detection depended on whether the intensity of the sensory input was above or below the threshold. But can your judgment also affect your ability to detect sensory input? Signal detection theory accounts for human judgment in sensation. This theory states that detecting a sensory input, called the signal, requires making a judgment, called the response, about the presence or absence of the signal, based on uncertain information (Green & Swets, 1966).

To understand this theory, think about the many jobs where people have to decide if items are imperfect. In restaurants, servers check the food before it goes out to the customers. In retail stores, employees check products before they go on display. Signal detection theory explains how situations like these can have one of four outcomes (Figure 5.5). If a signal is present—such as a flaw in a food order— and the person responds to it, the outcome is called a hit. If the person does not respond to the signal, the outcome is a miss. By contrast, if there is no signal but the person responds anyway, the outcome is a false alarm. If there is no signal and the person does not respond, the outcome is a correct rejection.

The person’s sensitivity to the signal is usually computed by comparing the hit rate with the false alarm rate. This comparison corrects for any bias the partici- pant might bring to the situation. Signal detection theory also explains how a

signal detection theory Detection of a faint stimulus requires a

judgment—it is not an all-or-none process.

Figure 5.5 Signal Detection Theory (a) Have you ever had a job where you had to look for flaws in food orders or products?

(b) According to signal detection theory, there are four possible outcomes when

a person is asked to detect the presence

of a sensory input, such as a flaw. These

outcomes depend on whether an input is

present. They also depend on the person’s

ability to judge the presence of an input.

This theory accounts for people’s biases

in making judgments about whether a

stimulus is present.

(a) (b)

Yes No

Response given? (For example:

Detect the flaw?)

Signal present? (For example: Is there a flaw?)

No

Yes Hit

(correct) Miss

(mistake)

False alarm

(mistake)

Correct rejection (correct)

162 ■ CHAPTER 5 SENSATION AND PERcEPTION

worker can be biased in situations like these. Imagine that a server gets paid extra money every time he notices that an order has a flaw, such as the wrong vegetable, and asks the cook to correct that flaw before the order goes to the table. Or imagine that a retail worker receives a bonus every time she detects damaged goods and removes them from the shelves. This financial incentive will result in workers being biased toward responding when they see flaws. This bias will result in more hits but also more false alarms. By contrast, imagine the worker has to pay a finan- cial penalty every time he wrongly delays a food order or she wrongly removes a retail product. The worker will have the opposite bias: toward not responding to a flaw. This bias will result in more misses but also more correct rejections.

Signal detection theory helps us understand how a person can be biased toward responding, or not responding, even given the same amount of sensory input. As you can imagine, all sorts of factors influence the decision to respond to a partic- ular sensory input. Consider, for example, the person’s experience, motivation, attention, training, and knowledge of the consequences of whatever response is made.

SENSORY ADAPTATION Our sensory systems are tuned to notice changes in our surroundings. It is important for us to be able to notice such changes because they might require responses. It is less important to keep responding to unchang- ing stimuli. Sensory adaptation is a decrease in sensitivity to a constant level of stimulation.

For example, imagine that you are studying and work begins at a nearby construction site. When the equipment starts up, the sound seems particularly loud and annoying. After a few minutes, the noise seems to have faded into the background. If a stimulus is presented continuously, the responses of the sensory systems that detect it tend to diminish over time. Similarly, when a continu- ous stimulus stops, the sensory systems usually respond strongly as well. If the construction noise suddenly halted, you would likely notice the silence.

sensory adaptation A decrease in sensitivity to a constant level

of stimulation.

■ Sensation is the detection of light, sound, touch, taste, and smell. Perception

is how the brain interprets this information.

■ Sensory receptors transduce sensory input into signals. Except for smell, this

information is sent to the thalamus and relevant parts of the cortex for further

processing.

■ Absolute threshold and difference threshold describe how much physical

stimulus must be present for detection to happen.

■ Signal detection theory explains how our judgments affect our ability to

detect input.

■ Our senses adapt to constant stimulation and detect changes in our

environment.

5.1 CHECKPOINT: How Do Sensation and Perception Affect Us?

HOW DO WE SEE? ■ 163

5.2 How Do We See?

LEARNINg gOALS READINg ACTIvITIES

a. Remember the key terms about visual sensation and

perception.

List all of the boldface words and write down their

definitions.

b. Understand the four steps in visual sensation and

perception.

Summarize in your own words the pathway from visual

sensory input to processing in cortical areas.

c. Analyze the two theories of color perception. Differentiate between trichromatic theory and opponent

process theory.

d. Understand the three categories of object perception.

Organize a table that names the three categories of object

perception mechanisms and summarizes each category in

your own words.

e. Apply depth perception and motion perception to your

own life.

Explain cues that have helped you perceive depth and

motion, providing one example of each type of perception

from your life.

Does a place look safe or dangerous? Does a person look friendly or hostile? Given that we acquire information through our senses, vision is an extremely impor- tant source of knowledge. Yet sight seems so effortless, so automatic, that most of us take it for granted. But every time you open your eyes, nearly half your brain springs into action. Your brain is racing to make sense of the light waves arriving in your eyes. Of course, the brain can do this only based on sensory signals from the eyes.

Sensory Receptors in Our Eyes Detect Light People sometimes describe the human eye as working like a crude camera. This analogy means that the eye focuses light to form an image. But the comparison does not do justice to the processes that enable you to see information. Intricate processes in your eyes are required for you to see as familiar an image as the face of a friend.

FOCUSINg LIgHT IN THE EYE What is the first step in seeing something, such as a chair or the face of a friend? Believe it or not, light bounces off that object. That light enters your eyes in the form of light waves (Figure 5.6). The waves pass through the cornea of your eye. The cornea is the eye’s thick, transparent outer layer (see Figure 5.6, Step 1).

The light then passes through the pupil. This feature is the small opening that looks like a dark circle at the center of the eye. The iris, a circular muscle, gives eyes their color and controls the pupil’s size to determine how much light enters the eye. In dim lighting, the iris allows the opening of the pupil to become larger to let more light into the eye. The iris also increases the size of the pupil when you see something you like, such as a beautiful painting or a cute baby (Tombs & Silverman, 2004).

164 ■ CHAPTER 5 SENSATION AND PERcEPTION

Transduction: Rods and cones convert light waves into signals. Those signals are processed by ganglion cells, which generate action potentials that are sent to the brain by the optic nerve.

3 Perception: Signals from each visual �eld are processed on one side of each retina. They travel along the optic nerve and through the thalamus, and they are processed in the visual cortex that is opposite the visual �eld.

4Sensation: Sensory receptors in the retina, called rods and cones, detect the light waves.

2Physical stimulus: Light waves re�ected from the image pass through the cornea and enter the eye through the pupil. The lens focuses the light on the retina.

1

Optic nerve

Thalamus

Left visual �eld

Right visual �eld

Optic chiasm

Left primary visual cortex

Right primary visual cortex

Ganglion cells

Cone

Cornea

Pupil

Light waves

Retina Fovea

Blind spot

Lens

Iris

Rod

Optic nerve

Optic nerve (to the brain)

Figure 5.6 How We See Shown here are the four steps in the

sensation and perception of visual

information.

Behind the iris, muscles change the shape of the lens. If you look at some- thing far from you, your lenses will flatten. This flattening enables you to focus on something in the distance. If you look at something close to you, your lenses will thicken so you can focus. If you look at something too close to you, your eyes will feel uncomfortable. They are straining because the muscles cannot make the lenses any fatter. At that point, you have to back away a bit to see the object.

Together, the cornea and lens focus light so you see objects accurately. Light is actually focused more by the cornea than by the lens. Because the lens is adjust- able, it fine-tunes how the light is bent. Glasses and contact lenses provide clear, focused vision by helping the lens bend the light. As we get older, the muscles of the lens lose their ability to change the shape of the lens. As a result, it becomes hard to focus on near objects. After about age 50, most of us have to hold our menus far away from us to be able to read them, or we need to get reading glasses to bend the light more than our lenses can.

RODS AND CONES The cornea and the lens work to focus light on the retina, the thin inner surface of the back of the eye (see Figure 5.6, Step 2). The retina contains the rods and cones, which allow sensation of the light waves. The rods and cones are the sensory receptors in the eye that transduce light waves into signals (see Figure 5.6, Step 3). The name of each type of visual sensory receptor cell comes from its distinctive shape.

Each retina holds approximately 120 million rods and 6 million cones. Near the center of the retina is a small region called the fovea. Here, cones are densely packed. Cones are spread throughout the rest of the retina (except in the blind spot, as you will see shortly). However, they become increasingly scarce near the outside edge. Cones are responsible primarily for vision under bright conditions and for

lens The adjustable, transparent structure

behind the pupil; this structure focuses

light on the retina, resulting in a crisp

visual image.

retina The thin inner surface of the back of the

eyeball; this surface contains the sensory

receptors.

rods Sensory receptors in the retina that detect

light waves and transduce them into

signals that are processed in the brain as

vision. Rods respond best to low levels

of illumination, and therefore they do not

support color vision or seeing fine detail.

cones Sensory receptors in the retina that detect

light waves and transduce them into

signals that are processed in the brain as

vision. cones respond best to higher levels

of illumination, and therefore they are

responsible for seeing color and fine

detail.

HOW DO WE SEE? ■ 165

Transduction: Rods and cones convert light waves into signals. Those signals are processed by ganglion cells, which generate action potentials that are sent to the brain by the optic nerve.

3 Perception: Signals from each visual �eld are processed on one side of each retina. They travel along the optic nerve and through the thalamus, and they are processed in the visual cortex that is opposite the visual �eld.

4Sensation: Sensory receptors in the retina, called rods and cones, detect the light waves.

2Physical stimulus: Light waves re�ected from the image pass through the cornea and enter the eye through the pupil. The lens focuses the light on the retina.

1

Optic nerve

Thalamus

Left visual �eld

Right visual �eld

Optic chiasm

Left primary visual cortex

Right primary visual cortex

Ganglion cells

Cone

Cornea

Pupil

Light waves

Retina Fovea

Blind spot

Lens

Iris

Rod

Optic nerve

Optic nerve (to the brain)

seeing both color and detail. When you look at the faces in Figure 5.6, do you see them clearly? If so, it is your cones that are processing the small features of each face and the colors of the clothes.

Unlike cones, the rods are concentrated at the retina’s edges. None are in the fovea. Also unlike cones, rods respond well at extremely low levels of light. Rods are responsible primarily for night vision. They do not support color vision, and they are poor at providing information about fine details. For these reasons, on a moonless night, objects appear in shades of gray. If you look directly at a very dim star on a moonless night, the star will appear to vanish because its light will fall on the fovea, where there are no rods. If you look just to the side of the star, the star will be visible, because its light will fall just outside the fovea, where there are rods.

FROM THE EYE TO THE BRAIN Our ability to perceive objects means that this initial visual stimulation must be processed in our brains. Rods and cones are the visual sensory receptors that transduce the information from light waves into messages that are modified by other support cells in the retina. But finally, the information about what the eye has sensed is delivered to the ganglion cells (see Figure 5.6, Step 3). Ganglion cells are the first true neurons in the visual system in that they fire action potentials.

The axons of each ganglion cell are gathered into a bundle. This bundle is called the optic nerve. The optic nerve exits the eye at the back of the retina (see Figure 5.6, Step 4). At the point where the optic nerve exits the retina, there are no rods or cones. As a result, you have blind spots in your left and right visual fields. Your brain automatically fills in this gap. Because you don’t seem to be missing visual information, you are not aware that blind spots exist in your field of vision. To find these blind spots, do the Try It Yourself activity on p. 166.

166 ■ CHAPTER 5 SENSATION AND PERcEPTION

Half of the axons in the optic nerves cross to the other side of the brain. The rest of the axons stay on the same side of the brain. The point where the axons cross is known as the optic chiasm (see Figure 5.6, Step 4). Say you are looking at a point in the distance. The arrangement of the axons causes all the visual informa- tion to the left of the point you are staring at (the left side of the visual field) to be sent to the right hemisphere of the brain. Everything to the right side of that point is sent to the left hemisphere of the brain. In each case, the information passes through the thalamus and travels to the primary visual cortex in the occipital lobes (see Figure 5.6, Step 4). This region of the brain provides basic information about what is seen. Basic information includes the orientation, size, and movement of objects in the visual field. However, more-complex information is processed later on in other specialized brain regions.

We Perceive Color Based on Physical Aspects of Light When you look at Figure 5.6, how do you know what colors the clothes are? An object appears to be a particular color because of two factors: the wavelengths of light that the object reflects and how the receptors in the eye process the light. Because of these two factors, we can identify millions of different shades of color.

PHYSICAL EXPERIENCE OF COLOR For humans, visible light consists of electromagnetic waves ranging in length from about 400 to 700 nanometers (abbreviated nm; this length is about one billionth of a meter; Figure 5.7). The physical qualities of this light correspond to the perception of color in different ways (Figure 5.8). One physical quality of light is the amplitude. The amplitude is the height of the light wave from base to peak. Psychologically, people experi- ence this quality as brightness. For example, brightness is the difference between a bright blue and a dark blue of the same shade.

The wavelength of the light wave is the distance from peak to peak. This distance determines your perception of both hue and saturation. The word hue refers to the distinctive characteristics that place a particular color in the spectrum. For example, a green hue might look more blue-green or more yellow-green, depending primarily on the light’s dominant wavelength when it reaches the eye. Saturation is

TRY IT YOURSELF: Find Your Blind Spot

To find the blind spot in your right eye, hold this book in

front of you. close your left eye and look at the X with

your right eye. Move the book toward and away from

your face until you can’t see the red dot. The red dot

“disappears” because it is in your blind spot, the point

on the retina where there are no receptors and the optic

nerve leaves the eye.

Instead of the red dot, did you see continuous blue

lines across the page? In this perceptual phenomenon,

the brain fills in the missing information with what you

would most likely see, based on the context.

X

HOW DO WE SEE? ■ 167

the intensity of the color. Saturation varies according to how many different wave- lengths of light are present in the sensory input. When only one wavelength of light is present, this wavelength primarily stimulates one type of cone receptor. That simple stimulation will yield a perception of a “pure” basic color, such as a vibrant blue, yellow, or red. In other words, we see the color as highly saturated. By contrast, when there are many wavelengths of light present, these wavelengths will stimulate many types of cone receptors. This complex stimulation will yield a perception of a less saturated color, such as a pale pastel pink.

TRICHROMATIC THEORY Most of us would have no problem saying that a certain flower is yellow rather than blue. But how do we know that? How do the physical aspects of light become the colors we perceive? Here our cone receptors come into play.

The trichromatic theory relates color perception to cone receptors. Trichro- matic means “three-color.” According to this theory, color perception results from activity across three different types of cone receptors. Each type of receptor is

400 500 600

Visible spectrum (wavelength in nanometers)

700

White light

Microwaves Radio wavesUVX-raysGamma rays Infrared

A prism can break apart visible light to show the spectrum of colors.

Figure 5.7 visible Light When white light shines through a prism,

the spectrum of color that is visible to

humans is revealed. As shown here, the

visible color spectrum is only a small

part of the electromagnetic spectrum: It

consists of electromagnetic wavelengths

from just under 400 nm (perceived as

the color violet) to just over 700 nm

(perceived as the color red).

Figure 5.8 Physical Aspects of Light Relate to Color Perception The amplitude and wavelength, physical aspects of visible light, are processed into the

perceptual experiences of brightness, hue, and saturation.

Short wavelength: The distance between peaks is short, so we perceive blue. Because only one wavelength is present, this blue is highly saturated, or “pure.”

Long wavelength: The distance between peaks is long, so we perceive red. Because only one wavelength is present, this red is highly saturated, or “pure.”

High amplitude: The height between baseline and peak is high, so we perceive the color as being bright.

Low amplitude: The height between baseline and peak is low, so we perceive the color as being dark.

Baseline

High amplitude Low amplitude

Long wavelength Short wavelength

trichromatic theory There are three types of cone receptor

cells in the retina that are responsible for

color perception. Each type responds

optimally to different, but overlapping,

ranges of wavelengths.

168 ■ CHAPTER 5 SENSATION AND PERcEPTION

sensitive to different wavelengths of light (Figure 5.9). Specifically, S cones are most sensitive to short wavelengths. This sensitivity leads to our ability to see blue. M cones are most sensitive to medium wavelengths. This sensitivity enables us to see green. L cones are most sensitive to long wavelengths. Thanks to this sensitiv- ity, we can see red. So, because wavelengths of light at about 570 nm stimulate the M and L cones equally, we perceive yellow.

Trichromatic theory also explains how we see a color based on the mixing of different wavelengths. What you see is determined by many wavelengths. When they are added together, the wavelengths have a combined influence on the eye’s receptors. For this reason, the combining of wavelengths is called additive color mixing. Such mixing is used by lighting designers in the theater (Figure 5.10a). For example, lighting designers can create yellow light by presenting a light of 570 nm. Alternatively, they can combine medium wavelengths that stimulate M cones (seen as green) and long wavelengths that stimulate L cones (seen as red). As far as the brain can tell, yellow light is the same as a combination of green light and red light. Either way, everyone in the theater sees the light as yellow. When red, green, and blue light are mixed, the combination looks white. This white light results because all of the visible wavelengths are present.

How we see colors in paint works somewhat differently. Paint colors are deter- mined by pigments. Pigments are chemicals on the surfaces of objects. These chemicals absorb different wavelengths of light and prevent them from being reflected. Whichever wavelengths are not absorbed are therefore reflected by the pigment and enter the eye. In other words, the color of a pigment is determined by the wavelengths that the pigment does not absorb. For this reason, the combining of pigments is called subtractive color mixing (Figure 5.10b).

Blue paint looks blue because the pigment does not absorb short wavelengths (about 440 nm). Yellow paint looks yellow because the pigment does not absorb medium and long wavelengths (about 570 nm). When these pigments are mixed, the combination absorbs a greater range of wavelengths. The color we see is due to the reflected wavelengths that are “left over.” When blue and yellow pigments are mixed, the leftover wavelengths—the ones not absorbed by the combination—are about 530 nm. As a result, the combination looks green. Similarly, when red, yellow, and blue pigments are mixed, the combination looks black. The black pigment results because nearly all the wavelengths of light of the visible spectrum are absorbed.

Figure 5.9 Trichromatic Theory Explains Color Perception Our perception of hue is determined by

the wavelength of the visible light that

reaches the eye. This graph shows how

each type of cone best absorbs light of

different wavelengths.

S cones are most sensitive to short wavelengths. This sensitivity results in perception of blue.

M cones are most sensitive to medium wavelengths. This sensitivity results in perception of green.

Yellow

L cones are most sensitive to long wavelengths. This sensitivity results in perception of red.

Wavelength (nanometers)

Cones’ sensitivity to light (percentage)

400

50

75

25

0

100

500 600 700

Figure 5.10 Additive and Subtractive Color Mixing (a) Additive color mixing is the combining of wavelengths of light. The varying

proportions of wavelength mixtures

determine the particular colors of light we

perceive. (b) By contrast, subtractive color mixing is the combining of pigments. The

varying proportions of pigment mixtures

determine the particular colors of paint we

perceive.

(b) Subtractive color mixing

(a) Additive color mixing

HOW DO WE SEE? ■ 169

OPPONENT PROCESS THEORY Some aspects of color vision cannot be explained by the responses of our cone receptors. For example, we have trouble visualizing certain color mixtures. It is easier to imagine reddish yellow or bluish green, say, than reddish green or bluish yellow. Moreover, the trichromatic theory does not explain certain perceptual experiences. For instance, some colors appear to be opposites (Figure 5.11). When we stare at a red image for some time, we see a green afterimage when we look away. When we stare at a green image, we see a red afterimage when we look away. Likewise, when we stare at a blue image for some time, we see a yellow afterimage when we look away. When we stare at a yellow image, we see a blue afterimage. These perceptual afterimage effects are better explained by opponent-process theory.

To understand color opposites, we move to the next stage in visual processing. Remember that cones are receptors that detect wavelengths of light. The cones process that sensory input, and that processing ultimately leads to our percep- tion of colors. Cones send the information to ganglion cells. The ganglion cells fire action potentials to send visual information to the brain. Some types of ganglion cells make it seem that red and green are opposites, whereas other types make it seem that yellow and blue are opposites. The ways that these different ganglion cells respond to cone input explains why we see colors as opposites.

Ultimately, how the brain converts light waves to the experience of color is quite complex. On the one hand, it can be understood by considering the response of cones to different wavelengths. On the other hand, processing by the ganglion cells leads to seeing colors as opposites. But what about people with color-number synesthesia (described at the start of this chapter)? These people perceive colors in written numbers even when the wavelengths the numbers are presented in will cause most people to perceive only black and white. This phenomenon reveals how each person’s perception of color, and other aspects of visual perception, are based on how that person’s own, unique brain processes information. Most synesthetes never know—until they test their perceptions—that their perceptions are different from other people’s.

We Perceive Objects by Organizing Visual Information Look at Figure 5.12. What do you see? In this reversible figure, some people see a younger woman. Some people see an older woman. As the psychologist James Enns (2005) notes, very little of what we call “seeing ” takes place in the eyes. What we see results from processing in the brain. In this case, then, how does information about the object’s features get organized into our individual visual experiences?

One explanation is based on the theory of Gestalt psychologists that perception is more than simply gathering sensory input (see Chapter 1). The German word Gestalt means “shape” or “form.” In psychology, Gestalt means “organized whole.”

Figure 5.11 Afterimages Reveal Color Opposites Focus on the dot in the middle of the

flag and stare at the flag for at least 30

seconds. Then look at the dot to the

right, on the white background. What do

you see? You should see a red, white, and

blue American flag. This result occurs due

to processing in the ganglion cells.

opponent-process theory The proposal that ganglion cells in the

retina receive excitatory input from one

type of cone and inhibitory input from

another type of cone, creating the

perception that some colors are opposites.

Figure 5.12 Reversible Figure What do you see when you look at this

figure? Some see the face of a younger

woman (her ear, her jawline, and a black

necklace). Other people see the face of an

older woman (an eye, a nose, and a black,

open mouth).

170 ■ CHAPTER 5 SENSATION AND PERcEPTION

The founders of Gestalt psychology postulated a series of laws to explain how our brains group the perceived features of a visual scene into organized wholes. Gestalt psychology holds that our brains use a number of built-in principles to organize sensory information. These principles explain why we perceive, say, “a car” as opposed to metal, tires, glass, hubcaps, fenders, and so on. For us, an object exists as a unit, not as a collection of separate features. Let’s consider these prin- ciples of object perception.

FIgURE AND gROUND One of the visual perception system’s most basic prin- ciples is organizing visual features into an object. In discussions of Gestalt prin- ciples, an object is a figure that is distinct from the background. The background is referred to as the ground. In identifying any figure, the brain assigns the rest of the scene to the ground. A classic illustration of this principle is the reversible figure (again, see Figure 5.12). Here, you can go back and forth in perceiving two possible figures—the younger woman or the older woman—but you cannot perceive them both at the same time. The “correct” assignment of figure and ground is ambiguous. Sometimes you perceive the relationship one way, and sometimes you perceive it the other way. This illusion demonstrates how visual perception of figure and ground is dynamic and ongoing.

gROUPINg Whether the object is a reversible figure or an “ordinary” object in the world, your visual system seeks to form a coherent image of what you are seeing. To form that image, the system must determine what parts “go together.” This process is called grouping. The Gestalt psychologists identified several prin- ciples that explain how visual grouping works (Figure 5.13).

Have you ever seen many geese together in one area? We tend to visually put the individual geese into one large group, a flock, because they look alike and they stay close together. This example shows how we group visual information based on the proximity of parts and by the similarity of parts. By clustering visual elements based on proximity and similarity, we are able to consider the scene as a whole rather than as the individual parts.

Now think about a common experience: You see a person, but the person is partially obscured by a table. Why didn’t you perceive the person and the table as

eProximity: Close �gures are grouped as an object. So we see these 16 dots as three groups of objects.

Similarity: Similar �gures are grouped in an object. So we see this rectangle as having two locked pieces.

ba Continuity: Intersecting lines are interpreted as continuous. So we see the green bar as one piece that continues behind the purple cylinder.

c Closure: Figures with gaps are interpreted as complete. So we see the �gure as one whole triangle.

d Illusory contours: Contours are perceived even when they do not exist. So we see the contours of a square here.

e

Figure 5.13 gestalt Principles of grouping Gestalt psychology describes several principles of grouping that explain how we perceive

features of the visual field as a unified, whole object.

grouping The visual system’s organization of

features and regions to create the

perception of a whole, unified object.

HOW DO WE SEE? ■ 171

parts of the same object? Clearly, we can determine what parts of visual input go together to make coherent forms. We can make out the person and the table, not the person-table. Three additional Gestalt principles are at work here: the continuity of a line, closure of gaps, and the creation of illusory contours.

BOTTOM-UP AND TOP-DOWN PROCESSINg How do we assemble infor- mation about parts into a perception of a whole object? According to most models, perceptual organization is hierarchical. Specifically, perception of objects and patterns occurs through bottom-up processing. This term means that processing begins with the external world and the sensory input, which is detected by sensory receptors. Then the information is processed from these basic, lower levels to higher, more conceptual levels within the brain.

Perception also includes top-down processing. This term means that informa- tion at higher levels of conceptual processing can influence object perception at lower, more basic levels in the processing hierarchy. Information at higher levels includes our prior experiences and our expectations. Unfortunately, faulty expec- tations can lead to faulty perceptions. On November 28, 1979, Air New Zealand Flight 901 crashed into the slopes of Mount Erebus, on Ross Island in Antarctica. The crash killed 237 passengers and 20 crew members. The pilots believed they were flying over the Ross Ice Shelf, where there are no mountains, so they reduced altitude to give the passengers a better view of the spectacular Antarctic land- scape (Figure 5.14a). However, the plane was actually far off course. Given the whiteout conditions and the pilots’ expectations, the flight crew failed to notice the 12,000-foot volcano looming in front of them (Figure 5.14b). In this case, top- down expectations influenced bottom-up processing of the visual information the pilots were seeing, and the consequences were tragic.

Figure 5.14 Ross Ice Shelf and Mount Erebus (a) The pilots on Air New Zealand Flight 901 expected

to see the flat terrain of the

Ross Ice Shelf in Antarctica. (b) This expectation led to tragic consequences when

the pilots failed to see Mount

Erebus, a 12,000-foot-high

volcano, directly in their flight

path. (b)(a)

bottom-up processing The perception of objects is due to

analysis of environmental stimulus input

by sensory receptors; this analysis then

influences the more complex, conceptual

processing of that information in the brain.

top-down processing The perception of objects is due to the

complex analysis of prior experiences and

expectations within the brain; this analysis

influences how sensory receptors process

stimulus input from the environment.

To remember what it means to process information from the bottom up or the top down, just remember this tip.

LEARNINg TIP: Bottom-Up and Top-Down Processing

WHEN YOU SEE PLEASE THINK MEANINg

Bottom-up Processing based on information about the basic stimulus properties

The processing of information that is based on the properties of the stimulus in the world

Top-down Processing based on information in your brain, at the top of your body

The processing of information that is based on your knowledge, personal experiences, and expectations

When We Perceive Depth, We Can Locate Objects in Space Look up from this book and reach for something in front of you, perhaps a pen or a coffee cup. To accomplish this simple task, you need to perceive the object coher- ently. You also have to know where the object is in space. Without this spatial ability, it would be very difficult to navigate in the world and interact with things and people. In fact, our brains use two types of cues to help us perceive depth. Binocular depth cues are based on input from both eyes together. Monocular depth cues are based on input from one eye alone.

BINOCULAR DEPTH PERCEPTION Look at the objects around you. You see them as three-dimensional. Indeed, they are three-dimensional. Yet inside your eyes, once the light reflected from the images hits your retinas, all of the depth information is lost. The information is represented on the retinas in two dimen-

sions only, just as it would be in a photograph. How can we perceive depth in the world if it is processed on the flat retinas in two dimensions?

To understand the process, look at something very close up. Hold your hand or your book up to your face. Repeatedly blink your left eye and

then your right eye. When you do this, does whatever you are look- ing at quickly change positions from the left to the right and back again? This perception of “jumping ” occurs because the retina of each eye has a slightly different view. Together, the different views on the retina are called binocular disparity. This phenomenon is one of the ways we perceive depth.

Because each eye has a slightly different view, the brain has access to two different, though overlapping, retinal images. The brain uses the disparity between these two retinal images to compute distances to nearby objects. By computing distances,

the brain enables us to perceive depth (Figure 5.15). But binocular disparity is an important cue for depth perception only when the objects are relatively close to us. And it requires using both eyes. So another set of cues also helps us perceive depth.

MONOCULAR DEPTH PERCEPTION Photographs, movies, videos, and tele- vision images are flat. Flat images have no depth, yet we perceive depth in them. What’s more, we perceive this three-dimensionality in two-dimensional images just by using one eye. For this reason, another set of visual cues are called monoc- ular depth cues. Artists routinely use these cues to create a sense of depth, so monocular depth cues are also called pictorial depth cues. For example, when you look at Figure 5.16, you can see depth in the picture in several ways. The Renais- sance painter, sculptor, architect, and engineer Leonardo da Vinci first identified many of these cues, which include occlusion, height in field, relative size, familiar size, linear perspective, and texture gradient.

Cues in Our Brains and in the World Allow Us to Perceive Motion You see something move. A person walks by, or a car whizzes past. You are aware of all this motion because you are sensing changes in illumination on your reti- nas. Changes in illumination, together with object recognition processes, enable

172 ■ CHAPTER 5 SENSATION AND PERcEPTION

Figure 5.15 Binocular Disparity We use both eyes to perceive depth

through binocular disparity, where each

retina has a slightly different view of the

world.

binocular depth cues cues of depth perception that arise

because people have two eyes.

monocular depth cues cues of depth perception that are available

to each eye alone.

The visual system sees every object from two distinct vantage points:

B BA

A

A

B

The distance between retinal images of objects A and B is different in the left eye …

from the distance between A and B in the right eye. This is an important cue for depth.

65 millimeters

HOW DO WE SEE? ■ 173

you to perceive that an object is in motion, changing locations. Two phenomena offer insights into how the visual system perceives motion: motion aftereffects and stroboscopic motion.

MOTION AFTEREFFECTS Motion aftereffects may occur when you gaze at a moving image for a long time and then look at a stationary scene. You experience a momentary impression that the new scene is moving in the opposite direction from the moving image. This illusion is also called the waterfall effect, because if you stare at a waterfall and then turn away, the scenery you are now looking at will seem to move upward for a moment.

Motion aftereffects are strong evidence that motion- sensitive neurons exist in the brain. According to the theory that explains this illusion, the visual cortex has neurons that respond to movement in a given direction. When you stare at a moving sensory input long enough, these direction-specific neurons start adapting to the motion. That is, they become fatigued and so are less sensitive. If the sensory input is suddenly removed, the motion detectors that respond to all the other directions are more active than the fatigued motion detectors. Thus you see the new scene moving in the other direction.

STROBOSCOPIC MOTION Motion pictures are called movies because they seem to be moving. Actually, though, movies are made up of still images. Each image is slightly different from the one before it. When the series is presented fast enough, we perceive the illusion of motion pictures. This perceptual illusion is called strobo- scopic motion (Figure 5.17).

Figure 5.16 Pictorial Depth Cues We can perceive depth with just one eye. In this image, six monocular depth cues create the

illusion of distance. Monocular depth cues are also called pictorial depth cues.

a c

be

f

d

Occlusion: A near object (woman’s head) blocks an object that is farther away (the building).

a

Height in field: Objects that are lower in the visual �eld (woman) are seen as nearer than objects that are higher in the visual �eld (man on the sidewalk at [c]).

b

Relative size: Objects that are farther away (man on the sidewalk) project a smaller retinal image than close objects of a similar size (man on the street next to [b]).

c

Familiar size: We know how large familiar objects are (car), so we can estimate how far away they are by the size of their retinal images.

d

Linear perspective: Seemingly parallel lines (sidewalk) appear to converge in the distance.

e

Texture gradient: As a uniformly textured surface recedes, its texture continuously becomes denser (pattern on the pavement).

f

Figure 5.17 How Moving Pictures Work This static series would appear transformed

if you spun the wheel. With the slightly

different images presented in rapid

succession, the stroboscopic movement

would tell your brain that you are watching

a moving horse.

174 ■ CHAPTER 5 SENSATION AND PERcEPTION

In 1912, the Gestalt psychologist Max Wertheimer conducted experiments on stroboscopic motion. Wertheimer flashed, at different intervals, two vertical lines placed close together. When the interval was less than 30 milliseconds, observers thought the two lines were flashing simultaneously. When the interval was greater than 200 milliseconds, they saw two lines being flashed at different times. Between those times, movement illusions occurred: When the interval was about 60 milli- seconds, the line appeared to jump from one place to another. At slightly longer intervals, the line appeared to move continuously. This phenomenon has brought us to productions such as Inception and The Amazing Spider-Man. In other words, all the special effects, fancy camera work, and fast editing you see in today’s movies are ways of manipulating a very simple perceptual trick.

■ In visual sensation, rods and cones transduce light waves into visual

information. This information is sent to the thalamus and primary visual

cortex for perceptual processing.

■ Trichromatic theory and opponent-process theory explain two ways that we

perceive color.

■ We perceive objects by determining figure and ground, by using grouping

principles, and through bottom-up and top-down processing.

■ We perceive depth based on how the brain processes binocular cues and

monocular cues.

■ We perceive motion by processing motion aftereffects and stroboscopic

motion.

5.2 CHECKPOINT: How Do We See?

5.3 How Do We Hear?

LEARNINg gOALS READINg ACTIvITIES

a. Remember the key terms about auditory sensation and

perception.

List all of the boldface words and write down their

definitions.

b. Understand the four steps in auditory sensation and

perception.

Summarize in your own words the pathway from auditory

sensory input to processing in cortical areas.

c. Apply pitch perception to your own life.

Describe how temporal coding and place coding allow

you to perceive a low-pitched sound and a high-pitched

sound.

d. Understand how sound intensity allows perception of a

sound’s location.

Summarize in your own words how you localize sound

based on the intensity of what you hear.

Like seeing, hearing is an important source of information about the world. Suppose you are driving along a crowded, curving street. You can’t see all the vehi- cles behind you. Suddenly you hear a siren coming toward you from back there. The siren lets you know that you should pull over to let an emergency vehicle pass.

HOW DO WE HEAR? ■ 175

Hearing is also called audition. This sensory mechanism enables us to determine what is happening in our environments. It provides a medium for spoken language. It brings pleasure to our lives, such as through music. In this section, let’s begin by discussing how sound waves are transduced in the auditory system. Then we’ll look at how we perceive the richness of sound information.

Auditory Receptors in Our Ears Detect Sound Waves The world is full of sound. A song plays, a person speaks, the TV drones, an over- head light hums. But everything you hear is merely changes in air pressure produced within your hearing distance. Just as objects in the world have no essential color, these changes in air pressure have no sound. Instead, your ability to hear is based on the intricate interactions of various regions of the ear and on processing in the brain.

An age-old question asks, “If a tree falls in the woods and no one is there to hear it, does it make a sound?” The answer is no. The falling of the tree makes vibrations in the air. It is only the way our ears and brains process the vibrations in the air that creates the perception of sound.

FROM THE EAR TO THE BRAIN Suppose you hear music, such as the sound of a saxophone. The sound waves from the music are the sensory input (Figure 5.18). The process of hearing begins when sound waves arrive at the shell-shaped struc- ture of your outer ear (see Figure 5.18, Step 1). The odd shape of the outer ear actually is functional: The shell shape increases the ear’s ability to capture sound waves and then funnel the waves down the auditory canal. When you have trouble hearing something, it helps to cup or bend your outer ear because you funnel even more sound waves into the auditory canal.

Next, the sound waves from the music travel down the auditory canal to the eardrum. The eardrum is a membrane stretched tightly across the canal. This membrane marks the beginning of the middle ear. When the sound waves hit the eardrum, they make it vibrate. The vibrations of the eardrum are transferred to three tiny bones, which together are called the ossicles. The ossicles amplify the vibrations even more. If you have ever experienced an ear infection, you know how important the eardrum is to hearing. When fluid builds up behind the eardrum, the membrane cannot vibrate properly, so it seems as if you have cotton in your ears. You can’t really hear much of anything.

At the start of the inner ear, the amplified vibrations reach the oval window. Though its name makes it seem like an opening, the oval window is actually another membrane. That membrane vibrates in turn. The oval window is located within the cochlea, a fluid-filled tube that curls into a snail-like shape. Running through the center of the cochlea is the thin basilar membrane. The oval window’s vibrations create pressure waves in the cochlear fluid that make the basilar membrane move in a wave. Movement of the basilar membrane stimulates the bending of hair cells. These cells are the sensory receptors for detecting auditory input (see Figure 5.18, Step 2).

The bending of the hair cells then causes them to transduce the auditory infor- mation into signals (see Figure 5.18, Step 3). This transduction initiates the creation of action potentials in the auditory nerve. The auditory nerve sends the information to the sensory processing center of the thalamus and finally to the primary auditory cortex in the brain (see Figure 5.18, Step 4). This region of the cortex processes the information. As a result, you perceive the music as coming from a saxophone.

eardrum A thin membrane that marks the beginning

of the middle ear; sound waves cause the

eardrum to vibrate.

cochlea A coiled, bony, fluid-filled tube in the inner

ear that houses the sensory receptors.

hair cells Sensory receptors located in the cochlea

that detect sound waves and transduce

them into signals that ultimately are

processed in the brain as sound.

Left primary auditory cortex

Right primary auditory cortex

Thalamus

Transduction: When the hair cells bend, they convert the pressure waves into signals that are sent to the brain by the auditory nerve.

3

Perception: The auditory nerve carries the neural signal �rst to the thalamus and then to the primary auditory cortex, which processes your perception of the sound.

4

Vibrations from the oval window enter the cochlea.

Sensation: Pressure waves in the cochlea move the basilar membrane, stimulating the sensory receptors, called hair cells, in your inner ear.

2

Signals exit the cochlea and enter the auditory nerve (to the brain).

Physical stimulus: Sound waves from the music enter your outer ear, making the eardrum vibrate. Then they pass to the middle ear, making the ossicles and the oval window vibrate. Finally, they pass to the cochlea, in your inner ear.

1

Outer ear

Eardrum

Cochlea Auditory nerve

Middle ear

Oval window

Hammer Anvil Stirrup

Inner ear

Semicircular canals

Sound Sound

Hair cells

Basilar membrane

Cochlea, partially uncoiled

Ossicles

Cochlea Auditory nerve

Auditory canal

You see it all the time: young adults, teenagers, and increasingly even

young children using ear buds to listen to music on portable devices.

The music is often so loud that people around them can hear it too. It

may surprise you to learn that this common activity has been linked

with noise-induced hearing loss (NIHL) in nearly 13 percent of American

children between the ages of 6 and 19—affecting more than 5 million

young people (centers for Disease control, 2013). Furthermore, research

suggests that some people in their 20s have hearing loss to a degree

that has traditionally been seen in 50-year-olds. But the good news is

that you don’t have to give up your iPod. If you know a little bit about

how your body processes sound waves to hear music, then you can

prevent hearing loss in these situations.

Any loud noise can damage hearing. People who work in noisy environ-

ments, such as factories, often experience hearing loss, especially if they

don’t wear ear protection. This hearing loss occurs because loud sounds

produce sound waves with greater amplitudes. These waves stimulate hair

receptors in the basilar membrane much more than do soft sounds, which

produce sound waves with smaller amplitudes. When hair cells in the basi-

lar membrane of the cochlea are repeatedly overstimulated, they lose the

ability to transduce sound waves.

One cause of damage to the hair cells is the volume, or loudness, of the

sound, which is measured in decibels (dB). The measured volume of some

sounds may surprise you—in the following table, for example, you can see

that a portable music player at maximum volume can be louder than a rock

concert! But volume is not the only source of damage. The length of expo-

sure to the noise is also important. For example, hearing an 85-dB noise for

8 hours causes the same amount of damage as 90 dB for 2 hours or 100 dB

for 15 minutes. Listening to the music player at top volume for 2 minutes can

USINg PSYCHOLOgY IN

YOUR LIFE:

Hearing Deficiencies From Listening to Loud Music With Ear Buds

Left primary auditory cortex

Right primary auditory cortex

Thalamus

Transduction: When the hair cells bend, they convert the pressure waves into signals that are sent to the brain by the auditory nerve.

3

Perception: The auditory nerve carries the neural signal �rst to the thalamus and then to the primary auditory cortex, which processes your perception of the sound.

4

Vibrations from the oval window enter the cochlea.

Sensation: Pressure waves in the cochlea move the basilar membrane, stimulating the sensory receptors, called hair cells, in your inner ear.

2

Signals exit the cochlea and enter the auditory nerve (to the brain).

Physical stimulus: Sound waves from the music enter your outer ear, making the eardrum vibrate. Then they pass to the middle ear, making the ossicles and the oval window vibrate. Finally, they pass to the cochlea, in your inner ear.

1

Outer ear

Eardrum

Cochlea Auditory nerve

Middle ear

Oval window

Hammer Anvil Stirrup

Inner ear

Semicircular canals

Sound Sound

Hair cells

Basilar membrane

Cochlea, partially uncoiled

Ossicles

Cochlea Auditory nerve

Auditory canal

Figure 5.18 How We Hear Shown here are the four steps in the sensation and perception of auditory information.

produce hearing loss. But listening with ear buds adds 6–9

dB of volume because the sound waves are produced inside

the auditory canal, close to the eardrum. In this situation, just

15 seconds of exposure can cause hearing loss. The result is

similar to the effect of listening to the noise from jet engines.

So how can you enjoy your music and avoid hearing

loss? Just follow these simple rules.

1. Use the 60/60 rule. Listen to your portable music device for 60 minutes at 60 percent of the maximum

volume. If you can’t tell what 60 percent of maximum

volume is, just use a volume where you can still under-

stand someone speaking to you in a normal voice from

an arm’s length away. After 60 minutes, give your ears a

break for a while. This recovery time significantly reduces

the chance of damaging your hearing.

2. Don’t use ear buds. Instead, use headphones that go over your ears. Noise dampening or canceling head-

phones are even better. These headphones reduce the

noise that you hear around you, so you don’t feel the

need to increase the volume on your music player.

3. Ringing ears are sending a warning. If your ears are ringing, buzzing, or roaring, or sounds seem muffled or

distorted 24 hours after you’ve been exposed to loud

noise, have your hearing checked by a doctor. Hear-

ing loss can be temporary and decrease over time, and

your doctor can help you avoid further, more perma-

nent damage.

NOISE IN THE ENvIRONMENT

LOUDNESS IN DECIBELS (APPROXIMATE)

LISTENINg TIME UNTIL DAMAgE TO HAIR CELLS (APPROXIMATE)

Whisper Normal conversation vacuum cleaner

20 40–60

70

Safe for any length of time

vehicle traffic 85 8 hours

gas lawnmower 90 2 hours

Average rock concert 100 15 minutes

Portable music player at maximum volume When using ear buds

110

116–119

2 minutes 15 seconds

Jet engine gunshot Rocket launch

140 165 180

Immediate damage occurs

177

We Perceive Sound Based on Physical Aspects of Sound Waves The psychologist Daniel Levitin is a former professional musician. In his best- selling book, This Is Your Brain on Music (2006), Levitin notes that music illus- trates the wonders of the auditory system. Each person’s unique perception of music depends on how that information is processed in the person’s brain. Through activity in different regions of the brain, the features of all the instruments come together to create the experience of music.

LOUDNESS AND PITCH OF SOUNDS Recall that what you eventually hear begins with changes in air pressure. The pattern of changes in air pressure over a period of time is a sound wave (Figure 5.19). The height of the sound waves is called the amplitude. The amplitude determines our perception of loudness: We hear sound waves with higher amplitudes as louder sounds.

The distance between peaks of sound waves is the wavelength. The frequency of the waves determines the pitch of the sound, which is how high or low the sound is. You hear a higher frequency as a higher-pitched sound and a lower frequency as a lower-pitched sound. The frequency of a sound is measured in vibrations per second, called hertz (abbreviated Hz). Most humans can detect sound waves with frequencies from about 20 Hz to about 20,000 Hz.

TEMPORAL AND PLACE CODINg Most of the sounds we hear, from conver- sations to concerts, are made up of many frequencies. Those frequencies activate a broad range of hair cells. How does the firing of hair cells signal different frequen- cies of sound, such as high notes and low notes in a song? In other words, how is pitch coded by the auditory system? There are two mechanisms for encoding the frequency of a sound wave. Both of these mechanisms operate at the same time in the basilar membrane.

Figure 5.19 Physical Aspects of Sound Waves Relate to Perception of Loudness and Pitch The amplitude and frequency of sound

waves are processed into the perceptual

experiences of loudness and pitch.

Low amplitude wave creates perception of a soft sound.

High amplitude wave creates perception of a loud sound.

Low-frequency wave results in perception of a low-pitched sound.

High-frequency wave results in perception of a high-pitched sound.

(a)

(b)

Amplitude

Frequency

Baseline

Baseline

1/10 second 1/10 second

178 ■ CHAPTER 5 SENSATION AND PERcEPTION

Temporal coding is the process of encoding relatively low frequencies. For example, when you hear a tuba, temporal coding is involved. For this type of coding, cochlear hair cells fire at a rate that matches the frequency of the sound wave. For instance, a 1,000-Hz tone causes hair cells to fire 1,000 times per second. This strict matching between the frequency of auditory stimulation and the firing rate of the hair cells occurs up to about 4,000 Hz. At higher frequencies, temporal coding can be maintained only if hair cells fire in volleys. That is, different groups of cells take turns firing, so that the overall temporal pattern matches the sound frequency.

The second mechanism for encoding frequency is place coding. Different frequencies are encoded by receptors at different locations on the basilar membrane. This membrane responds to sound waves like a clarinet reed, vibrating in resonance with the sound. Higher frequencies, such as the frequency of a train whistle, vibrate better at the membrane’s base by the oval window. Lower frequen- cies, such as the frequency of a foghorn, vibrate more toward the membrane’s tip. The frequency of a sound wave, therefore, is encoded by the hair cell receptors on the area of the basilar membrane that vibrates the most.

After the hair cells have fired based on the frequency of a sound wave, processing in the brain enables us to perceive that pitch. The processing of pitch takes place in the primary auditory cortex. Auditory neurons in the thalamus extend their axons to the primary auditory cortex. There, other neurons code the frequency of the auditory stimuli. The neurons toward the rear of the auditory cortex respond best to sounds at higher frequencies. The neurons toward the front of the auditory cortex respond best to sounds at lower frequencies.

LOCALIZATION Suppose you hear a siren while driving, but you can’t tell which direction the sound is coming from. Locating the origin of a sound is called local- ization. This ability is an important part of auditory perception. However, the hair cells cannot code where events occur. Instead, the brain integrates the different sensory information coming from each of our two ears.

Much of our understanding of auditory localization has come from research with barn owls. These nocturnal birds have finely tuned hearing, which helps them locate their prey. In fact, in a dark laboratory, a barn owl can locate a mouse through hearing alone.

The owl uses two cues to locate a sound (Figure 5.20). The first cue is the time when the sound arrives in each ear. The second cue is the amplitude, or intensity, of the sound wave in each ear. Unless the sound comes from exactly in front or in back of the owl, the sound will reach one ear first. Whichever side it comes from, it

temporal coding The perception of lower-pitched sounds

is a result of the rate at which hair cells

are stimulated by sound waves of lower

frequencies.

place coding The perception of higher-pitched sounds

is a result of the location on the basilar

membrane where hair cells are stimulated

by sound waves of varying higher

frequencies.

Figure 5.20 Perceiving Location and Loudness of Sound (a) Both barn owls and (b) humans draw on the intensity and

timing of sounds to

locate where sounds

are coming from.

Source of sound (here a cell phone)

1

The sound reaches the left ear �rst and is perceived as more intense. This cue indicates that the sound is closer to the left ear.

2

The sound reaches the right ear second and is perceived as less intense. This cue also indicates that the sound is closer to the left ear.

3

(a) (b)

HOW DO WE HEAR? ■ 179

180 ■ CHAPTER 5 SENSATION AND PERcEPTION

will sound softer on the other side because the owl’s head acts as a barrier. These differences in timing and intensity are minute, but they are not too small for the owl’s brain to detect and act on. Although a human’s ears are not as finely tuned to the locations of sounds as an owl’s ears are, the human brain uses information from the two ears in a similar way to localize sounds.

■ In auditory sensation, hair cells transduce sound waves into auditory

information. The auditory nerve sends this information to the thalamus and

the primary auditory cortex for perceptual processing.

■ We perceive pitch based on temporal coding and place coding.

■ Our pitch perception results from processing in neurons in the auditory cortex

that respond best to certain frequencies.

■ We perceive the location of a sound when the brain compares the time and

the intensity of a sound as it arrives at each ear.

5.3 CHECKPOINT: How Do We Hear?

5.4 How Can We Taste and Smell?

LEARNINg gOALS READINg ACTIvITIES

a. Remember the key terms about sensation and

perception of taste and smell.

List all of the boldface words and write down their

definitions.

b. Apply the four steps in sensing and perceiving taste and

smell to your own life.

Using the four steps in the pathway from sensory input to

processing in cortical areas, describe your perception of the

flavor of your favorite food.

c. Understand the reasons humans have evolved the senses

of taste and smell.

Describe in your own words how the senses of taste and

smell are important to the survival of humans.

When you think about your favorite foods, you can almost taste them. But regard- less of whether you swoon over a grilled steak, chow mein with mustard greens, or a spicy salsa, your appreciation of a certain food depends on more than taste alone. As you likely know from having had a cold, food seems tasteless when your nose is really stuffed up. This lack of perception happens because our sense of taste relies heavily on our sense of smell. Together, taste and smell produce the experience of flavor. In fact, flavor is based more on smell than on taste. This perceptual experi- ence does not take place in your mouth and nose, however. Like seeing and hearing, experiencing flavor occurs in your brain.

Receptors in Our Taste Buds Detect Chemical Molecules The sense of taste is also called gustation. Gustation has an adaptive function. In other words, taste is related to survival. If something you eat tastes really bad, you are likely to spit it out. This response is adaptive, because the job of taste is to keep poisons out of the digestive system while allowing good food in.

HOW cAN WE TASTE AND SMELL? ■ 181

FROM THE MOUTH TO THE BRAIN Suppose you taste a lemon (Figure 5.21). The physical stimulus that causes you to taste this food consists of chemical molecules that dissolve in saliva (see Figure 5.21, Step 1). The taste receptors are the sensory receptors that detect the chemical molecules. They are located in the taste buds (see Figure 5.21, Step 2). On the tongue, the taste buds reside in tiny, mushroom-shaped structures called papillae. But the taste buds are also spread throughout the mouth and throat. Most individuals have approximately 8,000 to 10,000 taste buds.

Food, fluid, or any other substance (e.g., dirt) will stimulate the taste buds. At that point, the taste receptors transduce the sensory input into action potentials (see Figure 5.21, Step 3). The taste information is sent to other brain regions through a set of nerves, primarily the facial nerve (see Figure 5.21, Step 4). After processing by the thalamus, the information is further processed in the gustatory cortex.

FIvE MAIN TASTES Like the other senses, taste involves a nearly infinite vari- ety of perceptions. These perceptions arise from the activation of unique combina- tions of receptors. Scientists once believed that different regions of the tongue are more sensitive to certain tastes, but we now know that the different taste buds are spread relatively uniformly throughout the tongue and mouth (Lindemann, 2001). Every taste experience is composed of a mixture of five basic qualities: sweet, sour, salty, bitter, and umami (Japanese for “savory” or “yummy”; pronounced “oo-MOM-ee”). Umami is the most recently recognized taste sensation (Krulwich, 2007). If you have eaten foods such as meat, cheese, or mushrooms, you may have noticed how they seem to be bursting with flavor. If so, you have experienced umami. Researchers are still investigating how the cells in the taste buds lead to perception of all five of these taste qualities.

Some people experience taste sensations intensely. This trait is determined largely by genetics. These individuals, known as supertasters, are highly aware of flavors and textures and are more likely than others to feel pain when eating very spicy foods (Bartoshuk, 2000). Supertasters have nearly six times as many taste buds as normal tasters. The more taste buds you have, the more intense your taste experiences will be.

Although it might sound enjoyable to experience intense tastes, many super- tasters are especially picky eaters because particular tastes can overwhelm them. When it comes to sensation, more is not necessarily better. Being a supertaster may also affect health. Supertasters tend to avoid bitter-tasting foods, which they find extremely distasteful. This avoidance may put the supertasters at risk for some cancers that bitter foods may protect against (Basson et al., 2005). The upside is that supertasters also dislike the taste of fatty, sugary foods, so they tend to be thin and may have a lower risk of cardiovascular disease. You can take the test in Try It Yourself, on p. 182, to see if you are a supertaster.

TASTE PREFERENCE Do you love or hate anchovies? Each of us has individ- ual taste preferences. These preferences come partly from our different numbers of taste receptors. The same food can actually taste different to different people, because the sensation associated with that food differs in their mouths. The texture of food also affects taste preferences: Whether a food is soft or crunchy, creamy or granular, tender or tough affects perception of the sensory experience. Another factor is whether the food causes discomfort, as can happen with spicy chilies. But cultural factors influence taste preferences as well.

taste buds Structures, located in papillae on the

tongue, that contain the sensory receptors

called taste receptors.

papillae Structures on the tongue that contain

groupings of taste buds.

182 ■ CHAPTER 5 SENSATION AND PERcEPTION

Sensation: The molecules stimulate sensory receptors called taste receptors. The taste receptors are located in taste buds that are grouped within papillae.

2 Transduction: The taste receptors convert the chemical molecules into signals that are transmitted to the brain primarily by the facial nerve.

3 4Physical stimulus: When you taste a lemon, the chemical molecules combine with saliva on your tongue.

1

Thalamus

To the brain

Perception: Primarily the facial nerve carries the neural signals �rst to the thalamus and then to the gustatory cortex. The gustatory cortex processes your perception of the sour taste.

4

Gustatory cortexTaste buds Taste receptor

Facial nerve (and other nerves)

Papillae

Figure 5.21 How We Are Able to Taste Shown here are the four steps in the sensation and perception of taste.

TRY IT YOURSELF: Are You a Supertaster?

Do you dislike the taste of broccoli, coffee, grapefruit,

and dark chocolate? If you answered yes, you may be

part of the approximately 25 percent of the population

that is several times more sensitive to strong and bitter

tastes than other people. To find out if you are a super-

taster, follow these simple steps.

1. Punch a small hole (about 7 millimeters or 0.25

inches) into a square of waxed paper.

2. Place a drop of blue food coloring on your tongue,

then put the waxed paper with the hole in it on top

of your tongue.

3. Use a magnifying glass to view the part of your

tongue that shows through the hole.

4. The pink dots are the papillae, which do not take

up the dye. count the number of papillae visible in

the hole.

If you have more than 30 papillae, you also have more

taste buds. If you have more taste buds, you may be a

supertaster.

Cultural influences on food preferences begin in the womb. One study of infant food preferences found that, through their own eating behaviors before and immediately following birth, mothers apparently pass their eating preferences on to their offspring (Mennella, Jagnow, & Beauchamp, 2001). The details of this study are summarized in the Scientific Thinking feature on p. 183. Once again, as noted throughout this book, the effects of nature and nurture are impossible to separate.

HOW cAN WE TASTE AND SMELL? ■ 183

Sensation: The molecules stimulate sensory receptors called taste receptors. The taste receptors are located in taste buds that are grouped within papillae.

2 Transduction: The taste receptors convert the chemical molecules into signals that are transmitted to the brain primarily by the facial nerve.

3 4Physical stimulus: When you taste a lemon, the chemical molecules combine with saliva on your tongue.

1

Thalamus

To the brain

Perception: Primarily the facial nerve carries the neural signals �rst to the thalamus and then to the gustatory cortex. The gustatory cortex processes your perception of the sour taste.

4

Gustatory cortexTaste buds Taste receptor

Facial nerve (and other nerves)

Papillae

SCIENTIFIC THINKINg: Infant Taste Preferences Affected by Mother’s Diet

Hypothesis: Taste preferences in newborns are in�uenced by their mothers’ food preferences during the months immediately before and after birth.

Research Method: Pregnant women were assigned at random to one of four groups. They were instructed to drink a certain beverage every day for two months before the baby’s birth and two months after the baby’s birth:

Results: Babies whose mothers were in Groups 1, 2, or 3 preferred the taste of carrot juice more than did babies whose mothers were in Group 4 and did not drink carrot juice.

Conclusion: Babies become familiar with the taste of foods their mothers consume around the time of their birth, and they prefer familiar tastes.

Question: Why might children prefer the tastes of foods regularly eaten by their mothers? Children are known for sometimes being picky eaters who are unwilling to try new foods. What kinds of foods do you think children are most reluctant to try?

Group 1: Group 2:

Group 3: Group 4:

carrot juice Before birth

carrot juice

water

water

water After birth

carrot juice

carrot juice

water

184 ■ CHAPTER 5 SENSATION AND PERcEPTION

Our Olfactory Receptors Detect Odorants When a dog is out for a walk, why does it sniff virtually every object and creature it encounters? The sense of smell, which is also called olfaction, is the dog ’s main way of perceiving the world. Our sense of smell is much weaker than that of dogs, and in fact of many animals. For example, dogs have 40 times more olfactory recep- tors than humans do and are 100,000 to 1 million times more sensitive to odors. Our less developed sense of smell comes from our ancestors’ reliance on vision. Yet the importance of smell to us in our daily lives is made clear, at least in West- ern cultures, by the vast sums of money we spend on fragrances, deodorants, and mouthwash.

FROM THE NOSE TO THE BRAIN Of all the senses, olfaction has the most direct route to the brain. But it may be the sense we understand the least. Like taste, smell begins when you sense chemical molecules that come from outside your body. The chemical molecules are called odorants. Say you smell a fresh loaf of bread (Figure 5.22). The odorants pass into your nose and through the upper and back portions of the nasal cavity (see Figure 5.22, Step 1). In the nose and the nasal cavity, a warm, moist environment helps the sensory receptors, called olfactory receptors, detect the odorant molecules. The olfactory receptors are embedded within the olfactory epithelium. This layer of tissue, as thin as a dime, is located deep in the nasal cavity (see Figure 5.22, Step 2).

olfactory epithelium A thin layer of tissue, deep within the

nasal cavity, containing the olfactory

receptors; these sensory receptors

produce information that is processed

in the brain as smell.

Perception: The olfactory nerve carries the neural signal from the olfactory bulb to the olfactory cortex. The olfactory cortex processes perception of the fresh bread. Smell is the only sense that is not processed through the thalamus.

4Physical stimulus: When you smell a loaf of bread, odorants pass into your nose and nasal cavity.

1 Sensation: The odorants stimulate sensory receptors called olfactory receptors. These receptors are located in the olfactory epithelium.

2 Transduction: The olfactory receptors convert the odorants into signals that are transmitted directly to the brain by the olfactory nerve.

3

Nasal passageOdorants

To the brain

Olfactory bulb

Olfactory epithelium

Olfactory nerve

Olfactory cortex

Olfactory receptors Olfactory

nerve

Figure 5.22 How We Are Able to Smell Shown here are the four steps in the sensation and perception of smell.

HOW cAN WE TASTE AND SMELL? ■ 185

Perception: The olfactory nerve carries the neural signal from the olfactory bulb to the olfactory cortex. The olfactory cortex processes perception of the fresh bread. Smell is the only sense that is not processed through the thalamus.

4Physical stimulus: When you smell a loaf of bread, odorants pass into your nose and nasal cavity.

1 Sensation: The odorants stimulate sensory receptors called olfactory receptors. These receptors are located in the olfactory epithelium.

2 Transduction: The olfactory receptors convert the odorants into signals that are transmitted directly to the brain by the olfactory nerve.

3

Nasal passageOdorants

To the brain

Olfactory bulb

Olfactory epithelium

Olfactory nerve

Olfactory cortex

Olfactory receptors Olfactory

nerve

The olfactory receptors transduce the odorants into signals that the brain will ultimately process (see Figure 5.22, Step 3). These signals are processed in the olfactory bulb, the brain center for smell. From the olfactory bulb, which is just below the frontal lobes, the olfactory nerve transmits smell information to various brain regions, including the olfactory cortex (see Figure 5.22, Step 4). Unlike all other forms of other sensory information, smell signals bypass the thalamus, the early relay station in the brain.

vARIETY OF SMELLS There are thousands of olfactory receptors in the olfac- tory epithelium. Each receptor responds to different odorants. It remains unclear exactly how these receptors encode distinct smells. One possibility is that each type of receptor is uniquely associated with a specific odor. For example, one type would encode only the scent of roses, and another would encode the smell of baked bread. This explanation is unlikely, however, given the huge number of scents we can detect. According to a recent estimate, humans can distinguish more than a trillion odorants (Bushdid, Magnasco, Vosshall, & Keller, 2014). Thus, a more likely possibility is that each odorant stimulates several types of receptors and the activation pattern across these receptors determines the final olfactory perception (Lledo, Gheusi, & Vincent, 2005). Remember that in all sensory systems, sensation and perception result from both the specificity of receptors and the larger pattern of receptor responses.

SMELL PERCEPTION Information about whether a smell is pleasant or unpleas- ant is processed in the brain’s prefrontal cortex. The smell’s intensity is processed

olfactory bulb A brain structure above the olfactory

epithelium in the nasal cavity; from this

structure, the olfactory nerve carries

information about smell to the brain.

186 ■ CHAPTER 5 SENSATION AND PERcEPTION

Kim was pretty pleased with herself. She had finished the

reading for her Marketing 101 class and was about to start on

psychology. She was looking forward to it, actually, because

reading about psychology did not feel like work. Even her

friends were interested in what she was learning in class.

However, sometimes they asked her things that seemed like

“pop psychology” rather than the real psychology she was

learning. For example, when Kim was reading the conscious-

ness chapter, one of her friends asked about “homicidal

somnambulism.” This term refers to when people kill other

people, and the killers claim to have been sleepwalking. These

cases are incredibly rare. Kim smiled and wondered, What will my friends latch on to in this chapter?

To relax before settling down with her textbook, Kim

logged on to her Facebook account and started chatting with

her friend Anton. The conversation turned to her reading, and

Kim mentioned some of chapter 5’s subject headings, such

as “How can We Taste and Smell?” Anton asked if she knew

why people remember things better based on smell. When

he gave the example of how smelling a particular perfume

always reminded him of his grandmother, Kim became curi-

ous about the phenomenon. Is there any scientific evidence for this? Maybe Anton just misses his grandmother so much he thinks he smells her perfume everywhere. Anton even mentioned that, according to a doctor on TV, loss of smell is

an early diagnostic sign of Alzheimer’s disease (a condition

associated with memory loss).

On the Web, Kim found references to a lot of research

on memory and the sense of smell. For example, accord-

ing to one study, people exposed to the smell of rosemary

had a greater ability to remember to do things (prospec-

tive memory) than people who were not exposed to that

smell. And a bunch of studies, discussed at the Depart-

ment of Veterans Affairs Web site, had found an association

between loss of smell and Alzheimer’s disease. However, the

studies didn’t show conclusively whether the brain degen-

eration of Alzheimer’s causes the loss of smell, or if the loss

of smell makes Alzheimer’s more likely. Maybe the truth,

Kim thought, is that aging is related to both Alzheimer’s and changes in smell. Still, I guess some of those Internet claims actually have been the subject of real psychological research.

The articles were interesting, but they did not help Kim

understand why smell and memory would be linked. When

she read chapter 5, the picture became much clearer.

qUESTION As the textbook explained, the intensity of smell is processed

in the amygdala. This brain region is associated with the

processing of both emotions and memory. Kim has realized

that the involvement of the amygdala in smell, emotions,

and memory makes sense. Can you think of how there might

be an evolutionary advantage to the relation between smell

and memory? What kind of smells might you expect to be

especially likely to trigger memories?

BEINg A CRITICAL CONSUMER: Sniffing Out the Truth About Smell and Memory Research

in the amygdala, a brain area involved in emotion and memory (Anderson, Christ- off, et al., 2003). Because of the amygdala’s role in processing smell, it is not surpris- ing that olfactory stimuli can evoke feelings and memories. For example, many people find that the aromas of certain holiday foods, the smell of bread baking, or the fragrances of particular perfumes generate fond childhood memories.

We can readily say whether an odor is pleasant or offensive to us. We can discriminate among thousands of different odors. However, according to the researchers Yaara Yeshurun and Noam Sobel (2010), most people are pretty bad at identifying odors by name. Try asking people to name the smells of odorous items from your refrigerator. You will probably find that people are unable to name the smell at least half the time (de Wijk, Schab, & Cain, 1995). You may also find that women are generally better than men at identifying odors (Bromley & Doty, 1995; Lehrner, 1993; Schab, 1991).

■ In taste sensation, taste receptors transduce chemical molecules into taste

information. The facial nerve sends this information to the thalamus and

gustatory cortex for perceptual processing.

■ We detect five basic taste sensations: sweet, sour, salty, bitter, and umami

(savory).

■ In the sensation of smell, olfactory receptors transduce odorants and send

smell information to the olfactory bulb. The olfactory nerve then transmits the

signals to the olfactory cortex for perceptual processing.

■ We can perceive and discriminate about 10,000 smells. But we are generally

poor at naming odors.

5.4 CHECKPOINT: How Can We Taste and Smell?

5.5 How Do We Feel Touch and Pain?

LEARNINg gOALS READINg ACTIvITIES

a. Remember the key terms about touch and pain sensation

and perception.

List all of the boldface words and write down their

definitions.

b. Understand the four steps in touch sensation and

perception.

Summarize in your own words the pathway from tactile

sensory input to processing in cortical areas.

c. Apply pain sensation and perception to your life. Describe how you would sense and perceive banging your

knee on the corner of a table.

d. Understand ways to control perception of pain. Describe in your own words how you can reduce your

perception of pain.

When you see, hear, taste, or smell something, receptors in just one small part of your body have been stimulated. But for the sense of touch, receptors exist all over your body. In fact, the skin is the largest organ for sensory reception.

Receptors in Our Skin Detect Temperature and Pressure Suppose you are splashed with cold water. Water or anything else that makes contact with your skin provides tactile stimulation (Figure 5.23, Step 1). Tactile stimulation produces the experience of touch. Touch conveys sensations of temperature, of pressure, and of pain. It also delivers a sense of where our limbs are in space.

FROM THE SKIN TO THE BRAIN Specialized receptors detect tempera- ture and pressure (see Figure 5.23, Step 2). These sensory receptors are embed- ded within the skin. For sensing temperature, there are warm receptors and cold receptors. Intense hot or cold stimuli can trigger both warm and cold receptors, however. Such simultaneous activation can produce strange sensory experiences,

warm receptors Sensory receptors in the skin that detect

the temperature of stimuli and transduce

it into information processed in the brain

as warmth.

cold receptors Sensory receptors in the skin that detect

the temperature of stimuli and transduce

it into information processed in the brain

as cold.

HOW DO WE FEEL TOUcH AND PAIN? ■ 187

188 ■ CHAPTER 5 SENSATION AND PERcEPTION

such as a false feeling of wetness. In addition, there are five types of pressure receptors. Some of these receptors are nerve fibers at the base of hair follicles. These receptors respond to movement of the hair. Four other types of pressure receptors are capsules in the skin. These receptors respond to continued vibration; to light, fast pressure; to light, slow pressure; or to stretching and steady pressure.

With tactile stimulation, such as being splashed with cold water, these recep- tors transduce the information into signals that will be sent to the brain (see Figure 5.23, Step 3). When skin is touched above the neck, the information is sent directly into the brain through cranial nerves (those that connect directly to the brain; see Figure 5.23, Step 4). When the touch is below the neck, the informa- tion is sent to the spinal cord and then spinal nerves transmit that information to the brain. In both cases, touch information travels first through the thalamus and then to the somatosensory cortex. In the somatosensory cortex, the information is processed.

PERCEPTION OF TOUCH How do you know where on your body you’re being touched? In the 1940s, the neurosurgeon Wilder Penfield studied patients under- going brain surgery. Penfield discovered that electrical stimulation of the primary somatosensory cortex could evoke the perception of touch in different regions of the body (Penfield & Jasper, 1954). Parts of the body that are located near each other, such as the hand and arm, are processed in adjacent brain areas in the somatosen- sory cortex. In this way, the body is effectively mapped out according to physical proximity. We saw this mapping in the homunculus of Figure 2.17 (right side).

For the most sensitive regions of the body, such as lips and fingers, a great deal of cortex is dedicated to processing touch. For less sensitive areas, such as the

Perception: For touches above the neck, cranial nerves send neural signals to the brain. But for touches below the neck, neural signals are sent to the spinal cord, and spinal nerves transmit them to the brain. Signals travel to the thalamus and then to the area of the somatosensory cortex that processes the body part that was touched. This processing makes you perceive the cold water on your neck.

4Physical stimulus: When you feel something on your skin, such as cold water, your skin registers the tactile stimulation.

1 Sensation: The water stimulates sensory receptors in the skin, called warm, cold, and pressure receptors.

2 Transduction: The warm, cold, and pressure receptors convert the stimulation into signals that are transmitted to the brain by various nerves.

3

To the brain

Skin surface

Pressure receptor

Pain receptor

Cold Heat

Temperature receptors:

Pressure receptor

Hair follicle

Various nerves

Somatosensory cortex

Thalamus

Cranial nerves and spinal nerves

Figure 5.23 How We Experience Touch Shown here are the four steps in the

sensation and perception of touch.

pressure receptors Sensory receptors in the skin that detect

tactile stimulation and transduce it into

information processed in the brain as

different types of pressure on the skin.

fast fibers Sensory receptors in skin, muscles, organs,

and membranes around both bones and

joints; these myelinated fibers quickly

convey intense sensory input to the brain,

where it is perceived as sharp, immediate

pain.

slow fibers Sensory receptors in skin, muscles, organs,

and membranes around both bones and

joints; these unmyelinated fibers slowly

convey intense sensory input to the brain,

where it is perceived as chronic, dull,

steady pain.

back and the calves, very little cortex is dedicated to processing touch. Caressing certain parts of the body feels so good because more of your brain processes that information.

We Detect Pain in Our Skin and Throughout the Body Ouch! You reach for a pan on the stove, not knowing that the handle is really hot. You pull your hand away quickly before you get badly burned. Just as taste can prevent you from eating something harmful, pain is part of a warning system that stops you from continuing activities that may harm you. Children born with a rare genetic disorder that leaves them insensitive to pain usually die young, no matter how carefully they are supervised. They simply do not know how to avoid activities that harm them or to report when they are ill (Melzack & Wall, 1982).

TWO TYPES OF PAIN RECEPTORS Most experiences of pain result when damage to the skin triggers pain receptors. The nerves that carry pain information are thinner than those for temperature and for pressure. These thinner nerves are found in all body tissues that sense pain: skin, muscles, membranes around both bones and joints, organs, and so on.

Two kinds of nerve fibers carry pain information to the brain. Fast fibers have myelinated axons. As described in Chapter 2, these axons are like heavily insulated electrical wires. They carry information very quickly. Fast fibers carry informa- tion that is perceived as sharp, immediate pains. By contrast, slow fibers have

HOW DO WE FEEL TOUcH AND PAIN? ■ 189

Perception: For touches above the neck, cranial nerves send neural signals to the brain. But for touches below the neck, neural signals are sent to the spinal cord, and spinal nerves transmit them to the brain. Signals travel to the thalamus and then to the area of the somatosensory cortex that processes the body part that was touched. This processing makes you perceive the cold water on your neck.

4Physical stimulus: When you feel something on your skin, such as cold water, your skin registers the tactile stimulation.

1 Sensation: The water stimulates sensory receptors in the skin, called warm, cold, and pressure receptors.

2 Transduction: The warm, cold, and pressure receptors convert the stimulation into signals that are transmitted to the brain by various nerves.

3

To the brain

Skin surface

Pressure receptor

Pain receptor

Cold Heat

Temperature receptors:

Pressure receptor

Hair follicle

Various nerves

Somatosensory cortex

Thalamus

Cranial nerves and spinal nerves

HAS IT HAPPENED

TO YOU?

Perceiving Very Cold or Very Hot Water

Have you ever dipped your hand in

a pool or held it under the shower

and decided that the water was the

right temperature? However, when

you jumped in, you immediately

realized the water was way too

cold or way too hot and you had to

get out right away. In this situation,

the perception of the water

temperature is much more extreme

because so many more receptors

are being stimulated. Next time, try

the water with your whole arm or

whole leg before you jump in!

190 ■ CHAPTER 5 SENSATION AND PERcEPTION

nonmyelinated axons. Without the insulation around these “wires,” some of the signal “leaks” out. Slow fibers carry information about chronic, dull, steady pains.

Suppose you had burned yourself on a hot pan handle (Figure 5.24). The moment your skin touched the pan, you would have felt a sharp, fast, local- ized pain. Then you would have felt a slow, dull, more diffuse pain. In this case, the fast fibers were activated by strong physical pressure and temper- ature extremes. The slow fibers were activated by changes in the damaged skin tissue. Both fast pain and slow pain are adaptive. Fast pain leads us to recoil from harmful objects and there- fore is protective. Slow pain keeps us from using the affected body parts and therefore helps them recover from injury. Like all other sensory experi- ences, the actual perception of pain is created by the brain.

gATE CONTROL THEORY Pain is a complex experience that depends on biological, psychological, and cultural factors. The psychologist Ronald Melzack conducted pioneer-

ing research in this area. For example, he demonstrated that psychological factors, such as past experiences, are extremely important in determining how much pain a person feels.

With his collaborator Patrick Wall, Melzack formulated the gate control theory of pain. According to this theory, we experience pain when pain receptors are activated and a neural “gate” in the spinal cord allows the signals through to the brain (Melzack & Wall, 1982). These ideas were radical in that they viewed pain

as a perceptual experience within the brain rather than simply a response to nerve stimulation. The theory states that pain signals are transmitted by thin nerve fibers. These fibers can be blocked at the spinal cord (prevented from reaching the brain) by the firing of larger sensory nerve fibers involved in the perception of touch. Thus, sensory nerve fibers can “close a gate” and reduce the perception of pain. This is why scratching an itch is so satisfying, why rubbing an aching muscle helps reduce the ache, and why vigorously rubbing the skin where an injection is about to be given reduces the needle’s sting.

It’s easy to remember what type of pain we perceive based on information

carried by fast fibers and by slow fibers.

LEARNINg TIP: Fast and Slow Fibers

About being hit with the pointy edge of the letter F (for Fast).

Fast fibers carry information that we perceive as sharp, immediate pain.

About being hit with the curved edge of the letter S (for Slow).

Slow fibers carry information that we perceive as dull, steady pain.

Figure 5.24 Types of Pain A painful touch, such as a burn, creates two types of pain. Activation of fast

fibers leads to perception of intense pain. Activation of slow fibers leads to

the perception of duller, throbbing pain.

HOW DO WE FEEL TOUcH AND PAIN? ■ 191

CONTROLLINg PAIN When you are in pain, does the pain feel worse when you’re wide awake and active or when you’re trying to sleep? Distraction can reduce your perception of pain. When ready for sleep, you generally try to remove distractions. As a result, the pain probably feels more intense. Without distractions, you might focus on or worry about the pain, thus increasing your pain perception. So, as you prepare for a painful procedure or suffer after one, try to distract yourself. Don’t focus on or worry about the pain. Watching an entertaining movie can help reduce pain perception, especially if it is funny enough to elevate your mood. And Swedish researchers found that listening to music was an extremely effective means of reducing postoperative pain, perhaps because it helps patients relax (Engwall & Duppils, 2009).

Keep in mind, however, that severe pain is a warning that something in the body is seriously wrong. If you experience severe pain, you should be treated by a medical professional.

Internal Sensory Systems Help Us Function in Space Humans, like other animals, have several internal sensory systems in addition to the five primary senses. These systems help us find and maintain our position in space. One such system is the kinesthetic sense. Some researchers group the kines- thetic sense with the touch senses. Kinesthetic sensations come from receptors in muscles, in tendons, and in joints. This information enables us to coordinate voluntary movement and is invaluable in avoiding injury.

You experience your kinesthetic sense every day. For example, you can pinpoint your position in space. You register the movements of your body and your limbs. Without these abilities, you would be unable to perform activities such as yoga (Figure 5.25a).

The vestibular sense uses information from receptors in structures of the inner ear called the semicircular canals (see Figure 5.18). These canals contain a liquid that moves when the head moves, bending hair cells in the canals. The bending generates signals that inform us of the head’s rotation. In this way, it is responsible for a sense of balance. Balance enables us to perform activities such as riding a bike or walking on a balance beam (Figure 5.25b).

If an inner-ear infection or standing up quickly has made you dizzy, you have experienced a disturbance in your vestibular sense. And the experience of being seasick or carsick results in part from conflicting signals arriving from the visual system and the vestibular system.

(a)

Figure 5.25 Kinesthetic and vestibular Senses (a) Our kinesthetic sense tells us how our body and limbs are positioned in space.

(b) Our vestibular sense allows us to maintain balance.

(b)

■ In touch, sensory receptors transduce information about pressure and

temperature. Nerves then send this information to the thalamus and

somatosensory cortex for perception.

■ For pain, fast fibers transduce information about immediate, sharp pain. Slow

fibers transduce information about chronic, dull pain.

■ Our kinesthetic sense lets us judge where our body and limbs are in space.

The vestibular sense aids balance by judging direction and intensity of head

movements.

5.5 CHECKPOINT: How Do We Feel Touch and Pain?

BIG QUESTION LEARNING GOALS

B IG

P IC

T U

R E

a. Remember the key terms about visual sensation and perception.

b. Understand the four steps in visual sensation and perception.

c. Analyze the two theories of color perception.

d. Understand the three categories of object perception.

e. Apply depth perception and motion perception to your own life.

5.2 How Do We See?

a. Remember the key terms about sensation and perception.

b. Apply the four steps from sensation to perception to your life.

c. Understand absolute threshold and difference threshold.

d. Apply signal detection theory to real life.

5.1 How Do Sensation

and Perception

Affect Us?

a. Remember the key terms about auditory sensation and perception.

b. Understand the four steps in auditory sensation and perception.

c. Apply pitch perception to your own life.

d. Understand how sound intensity allows perception of a sound’s location.

5.3 How Do We Hear?

a. Remember the key terms about sensation and perception of taste and smell.

b. Apply the four steps in sensing and perceiving taste and smell to your own life.

c. Understand the reasons humans have evolved the senses of taste and smell.

5.4 How Can We Taste

and Smell?

a. Remember the key terms about touch and pain sensation and perception.

b. Understand the four steps in touch sensation and perception.

c. Apply pain sensation and perception to your life.

d. Understand ways to control perception of pain.

5.5 How Do We Feel

Touch and Pain?

192 ■ CHAPTER 5 SENSATION AND PERcEPTION

BIG PIcTURE ■ 193

KEY TERMS CHECKPOINT

■ In visual sensation, rods and cones transduce light waves into visual information. This information is sent to the thalamus and primary visual cortex for perceptual processing.

■ Trichromatic theory and opponent- process theory explain two ways that we perceive color.

■ We perceive objects by determining figure and ground, by using grouping

lens retina rods cones trichromatic theory opponent-process theory grouping bottom-up processing top-down processing binocular depth cues monocular depth cues

principles, and through bottom-up and top-down processing.

■ We perceive depth based on how the brain processes binocular cues and monocular cues.

■ We perceive motion by processing motion aftereffects and stroboscopic motion.

■ Sensation is the detection of light, sound, touch, taste, and smell. Perception is how the brain interprets this information.

■ Sensory receptors transduce sensory input into signals. Except for smell, this information is sent to the thalamus and relevant parts of the cortex for further processing.

■ Absolute threshold and difference threshold describe how much physical

sensation perception sensory receptors transduction absolute threshold difference threshold signal detection theory sensory adaptation

■ In auditory sensation, hair cells transduce sound waves into auditory information. The auditory nerve sends this information to the thalamus and the primary auditory cortex for perceptual processing.

■ We perceive pitch based on temporal coding and place coding.

■ Our pitch perception results from processing in neurons in the auditory cortex that respond best to certain frequencies.

■ We perceive the location of a sound when the brain compares the time and the intensity of a sound as it arrives at each ear.

eardrum cochlea hair cells temporal coding place coding

■ In taste sensation, taste receptors transduce chemical molecules into taste information. The facial nerve sends this information to the thalamus and gustatory cortex for perceptual processing.

■ We detect five basic taste sensations: sweet, sour, salty, bitter, and umami (savory).

■ In the sensation of smell, olfactory receptors transduce odorants

taste buds papillae olfactory epithelium olfactory bulb

and send smell information to the olfactory bulb. The olfactory nerve then transmits the signals to the olfactory cortex for perceptual processing.

■ We can perceive and discriminate a huge variety of smells. But we are generally poor at naming odors.

■ In touch, sensory receptors transduce information about pressure and temperature. Nerves then send this information to the thalamus and somatosensory cortex for perception.

■ For pain, fast fibers transduce information about immediate,

warm receptors cold receptors pressure receptors fast fibers slow fibers

sharp pain. Slow fibers transduce information about chronic, dull pain.

■ Our kinesthetic sense lets us judge where our body and limbs are in space. The vestibular sense aids balance by judging direction and intensity of head movements.

stimulus must be present for detection to happen.

■ Signal detection theory explains how our judgments affect our ability to detect input.

■ Our senses adapt to constant stimu lation and detect changes in our environment.

For a self-quiz on this chapter, go to the back of the book and find Appendix B: Quizzes.

BIG QUESTIONS 6.1 What Are the Three Ways We Learn? 6.2 How Do We Learn by Classical Conditioning? 6.3 How Do We Learn by Operant Conditioning? 6.4 How Do We Learn by Watching Others?

6 Learning The parTy was greaT, the DJ was cool, and the food was terrific. Especially the shrimp—and

you ate a lot of them. But almost immediately something didn’t feel right, and you ended up

having a night that you would like to forget. Even now, a year later, the sight, the smell, and the

thought of shrimp makes you feel ill. You never eat them anymore.

Sound familiar? Maybe it wasn’t shrimp, but if you’ve ever had a similar response to a misadventure

with food, you have experienced conditioned taste aversion, a particular form of learning. Conditioned

taste aversion is not limited to humans. You can see a striking example of it in the way wolves have

learned not to prey on domestic livestock.

195

196 ■ ChapTer 6 lEarNING

Gray wolves of the Northern rocky Mountain region were native

to Yellowstone National Park when the park was created in 1872.

By the 1970s, however, all the wolves in the park had been killed as

part of a predator control plan. Some gray wolves remained in the

lower 48 states, but in 1974 the species was listed as endangered.

In 1987, the U.S. Fish and Wildlife Service announced a recovery

plan to reintroduce wolves to Yellowstone Park. at the same time,

some conservation groups were proposing to reintroduce other

sub species of wolves, such as the Mexican wolf, to other parts of

the United States. In all of these regions, the local farmers and ranchers were

afraid the wolves would prey on their sheep and cattle. an important part of all

the reintroduction plans, therefore, was gaining the support of the farmers and

ranchers by finding creative ways to limit predation by wolves. Here is where

the psychology behind conditioned taste aversion came into play.

Sheep carcasses treated with nonlethal doses of poison were placed where

wolves would find them (Figure 6.1). after eating the meat, the wolves imme-

diately vomited. Just as you now avoid food that made you sick in the past,

the wolves soon learned to associate eating sheep with becoming ill. So

they avoided preying on sheep. as a result, many ranchers stopped oppos-

ing re introduction of wolves. Thus conditioned taste aversion for the flavor of

sheep’s meat has allowed the wolves to flourish in regions where agricultur-

ists would normally exterminate them. Today, in several regions of the United

States, wolves have been taken off the endangered species list.

Using conditioned taste aversion to help wolves learn not to eat sheep is

an example of how psychology can be put to work in “the real world.” The

principles behind the wolves’ learning are also the basis for some of the ways

that humans learn. In this chapter, we examine how learning takes place. This

material represents some of psychology’s major contributions to our under-

standing of behavior. learning theories have been used to improve quality of

life and to train humans as well as nonhuman animals to learn new tasks. To

understand all behavior, we need to know what learning is.

6.1  What Are the Three Ways We Learn?

FIgUre 6.1 wolves experiencing Conditioned Taste aversion Conditioned taste aversion helps train wolves not to eat domestic livestock when wolves are reintroduced to areas in the United States.

LearnIng goaLs readIng aCTIvITIes

a. remember the key terms about learning. list all of the boldface words and write down their definitions.

b. Understand the three main types of learning. Describe these types of learning using your own words.

c. apply learning to your life. Provide examples from your own experience of the two types of non-associative learning.

d. Understand how the brain changes during learning. Summarize in your own words how long-term potentiation explains learning in the brain.

WHaT arE THE THrEE WaYS WE lEarN? ■ 197

Learning is a change in behavior, resulting from experience. Learning is central to almost all areas of human existence. It makes possible our basic abilities (such as walking and speaking) and our complex ones (such as flying airplanes, perform- ing surgery, or maintaining intimate relationships). What music you like, how you choose to dress, social rules about how close you stand to someone else, cultural values about whether you exploit or preserve the environment—learning helps shape all these and many other aspects of daily life. One of the basic questions we must ask, then, is: How do we learn?

We Learn From Experience The processes that allow us to learn have been debated for centuries, though more formal learning theory arose in the early twentieth century. Formal learning theory was developed partly because some psychologists were not satisfied with the Freudian ideas then at the heart of psychological theorizing. Recall from Chapter 1 that Freud and his followers used verbal report techniques, such as dream analysis and free association. They aimed to assess the unconscious mental processes that they believed were the primary determinants of behavior. But other psychologists argued that Freudian theory was unscientific and ultimately meaningless, and they developed theories of behavior and learning that were based on events others could observe.

John Watson, in particular, rejected any psychological approach that did not focus on what could be observed directly (Watson, 1924). According to Watson, observable behavior was the only valid indicator of psychological activity. Recall that this idea was the basis for the approach that came to be known as behav- iorism. In formulating his ideas on behaviorism, Watson was influenced by the seventeenth-century philosopher John Locke. An infant, Locke argued, is a tabula rasa (Latin for “blank slate”). Born knowing nothing, the infant develops over time by acquiring all of its knowledge through sensory experiences. Building on this foundation, Watson stated that environment and its associated effects on animals were the only determinants of learning.

Behaviorism was also the basis for B. F. Skinner’s groundbreaking studies of animals, often using pigeons or rats. Skinner designed these experiments to discover the basic rules of learning. He found that by giving an animal food for doing particular actions, he could radically change that animal’s behavior.

Modern psychologists agree that learning results from an individual’s experi- ence. Learning occurs when an animal or human benefits from experience so that its behavior is better adapted to the environment. Indeed, the ability to learn is crucial for all creatures. To survive, animals and humans need to learn things such as which sounds indicate potential dangers, what foods are dangerous, and when it is safe to sleep. Psychologists have divided learning into three main types: non- associative learning, associative learning, and learning by watching others. All of these types of learning are described in this chapter.

We Learn in Three Ways In non-associative learning, a person learns about one stimulus, which is infor- mation in the external world. A stimulus could be a sight, smell, or sound, for example. One important form of non-associative learning is habituation, where an individual is exposed to a stimulus for a long time, or repeatedly. Eventually, the individ ual’s behavioral response to that stimulus decreases (Figure 6.2a).

learning a change in behavior, resulting from experience.

habituation a decrease in behavioral response after lengthy or repeated exposure to a stimulus.

FIgUre 6.2 Two Forms of non-associative Learning (a) Habituation: Suppose you live or work in a noisy environment. You learn to ignore the constant noise, because you do not need to respond to it. (b) Sensitization: Suppose you’re sitting with your brother. He keeps annoying you, until finally you react.

(b)

(a)

198 ■ ChapTer 6 lEarNING

Habituation happens particularly if the stimulus is neither harmful nor rewarding. For example, if an animal experi- ences a new stimulus, such as hearing a sound, it will pay attention for a while, because the sound might indicate a potential danger. If the sound does not result in a threat, the animal soon learns to ignore it. In our everyday lives, we also constantly habituate to meaningless events around us (see Try It Yourself ).

sensitization is a second form of non-associative learning. It takes place when an individual is exposed to a stimulus for a long time, or many times, and then has an increased behavioral response. In general, sensitization

leads to heightened preparation to respond in an important situation where there is some potential harm or reward (Figure 6.2b). For instance, suppose that while you are studying, you smell something burning. You probably will not habituate to this smell, because it is an important stimulus. You might focus even greater attention on the smell to determine whether it is just a candle, another student burning her dinner, or something potentially dangerous.

Unlike non-associative learning, associative learning requires understand- ing how two or more pieces of information are related to each other. Associations develop through two types of conditioning. The first type, classical conditioning, occurs when you learn that two stimuli go together. For example, if you always hear a certain kind of music during scary scenes in a movie, you learn to feel anxious whenever you hear that music. The second type, operant conditioning, occurs when you learn that a behavior leads to a particular outcome. For example, you

sensitization an increase in behavioral response after lengthy or repeated exposure to a stimulus.

This graphic will help you understand the relationship between the three main types of learning and all of the subtypes.

LearnIng TIp: Types of Learning

Types of learning

When we learn that a stimulus predicts another stimulus.

When we learn that a behavior leads to a certain outcome.

When our behavioral response to a stimulus decreases.

When our behavioral response to a stimulus increases.

When we learn or change a behavior after watching a person engage in that behavior.

Learning to engage in a behavior or not, after seeing others being rewarded or punished for performing that action.

Imitating a behavior seen in others.

Classical conditioning

Observational learning

Modeling Vicarious conditioning

Operant conditioning

Watching others

Learning about a stimulus, such as a sight or a sound, in the external world.

Learning the relationship between two pieces of information.

Learning by watching how others behave.

Non-associative Associative

Habituation Sensitization

Try IT yoUrseLF: Habituation

right now, you can experience learning about a stimu- lus through habituation. Sit back and listen to the back- ground sounds wherever you are. Perhaps you can hear the hum of a light, a computer fan whirring, or music playing nearby. But did you notice this noise before it was pointed out to you? No, because you habituated to it. and in a few minutes, because of habituation, you will probably stop noticing the noise again.

WHaT arE THE THrEE WaYS WE lEarN? ■ 199

learn that studying leads to better grades. The third type of learning—learning by watching others—is just what it sounds like. Both humans and animals can learn by watching others, such as through observational learning, modeling, and vicari- ous conditioning. For example, you might have learned the latest popular dance by watching a YouTube video.

These main ways that we learn are summarized in the Learning Tip on p. 198. In later sections of the chapter, we consider each type of learning in more detail. First, let’s look briefly at what happens in the brain when we learn.

The Brain Changes During Learning All the types of learning we’ve just described result from experience. But what happens in the brain during learning? Exposure to environmental events actually causes changes in the brain that allow learning to occur. As discussed in Chapter  2, the psychologist Donald Hebb proposed that learning results from alterations in the connections between synapses. Recall that, according to Hebb, when one neuron excites another, some change takes place that strengthens the connection between the two neurons (“cells that fire together, wire together”). After that origi- nal event, the firing of one neuron becomes increasingly likely to cause the firing of the other neuron.

To understand how learning occurs in the brain, researchers have investigated the enhanced activity that results from the strengthening of synaptic connec- tions between neurons. This phenomenon is known as long-term potentiation (LTP). This term is easy to remember if you know that the word potent suggests something is “strong.” So potentiation indicates strengthening of synaptic connections that allow us to learn. A lot of evidence supports the idea that long- term potentiation is involved in learning and memory (Cooke & Bliss, 2006; Nabavi et al., 2014). For instance, LTP effects are most easily observed in brain sites known to be active in learning and memory, such as the hippocampus. What’s more, the same drugs that improve learning also lead to increased LTP, and those that block learning also block LTP.

■ learning is a change in behavior, resulting from experience. There are three main types of learning.

■ Non-associative learning about a stimulus happens through habituation and sensitization.

■ associative learning about relationships between events occurs through classical conditioning and operant conditioning.

■ learning also occurs when we watch what others do.

■ learning occurs when synaptic connections in the brain become stronger over time through long-term potentiation (lTP).

6.1 CheCKpoInT: What Are the Three Ways We Learn?

200 ■ ChapTer 6 lEarNING

6.2  How Do We Learn by Classical Conditioning ?

has IT happened

To yoU?

Experiencing Classical Conditioning

Does the smell of french fries make your mouth water? If so, then simply seeing the sign for a restaurant with fries you like may have made your mouth water. If this happened, you were classically conditioned!

classical conditioning a type of learned response in which a neutral object comes to elicit a response when it is associated with a stimulus that already produces a response.

It’s only a movie, but when the music starts to play, we feel tense as we watch the woman descend into the dark basement. The music helps make the situation scary. We just know that something bad is about to happen to her. But how do we know this? We know it because we have learned the association between the presence of certain music and bad things happening to the characters in the movie. This kind of learning is so familiar because it has happened to all of us (see Has It Happened to You?). We even describe it with a familiar phrase: acting like Pavlov’s dog. But what was Pavlov’s dog, and what does it have to do with learning?

Through Classical Conditioning, We Learn  That Stimuli Are Related Ivan Pavlov was a Russian physiologist who won a Nobel Prize in 1904 for his research on the digestive system (Figure 6.3a). Pavlov was interested in the salivary reflex, which is an automatic and unlearned response that occurs when food is presented to a hungry animal, including a human. To investigate the digestive system, Pavlov created an apparatus that measured how various types of food placed into a dog ’s mouth resulted in different amounts of saliva (Figure 6.3b).

Like so many major scientific advances, Pavlov’s contribution to psychology started with a simple observation. One day, he realized that the dogs he was study- ing were salivating before they actually tasted their food. In fact, the dogs began to salivate the moment they saw the bowls that contained the food or whenever the lab technician who usually delivered the food walked into the room. Pavlov’s genius was in recognizing that this behavioral response was a window into the working mind. Unlike innate reflexes, such as salivating when actually tasting the food, salivating at the sight of a bowl or of a person is not automatic. There- fore, that response must have been acquired through experience by associating two stimuli with each other. In other words, the dogs showed learning by classical conditioning. This insight led Pavlov to devote the rest of his life to studying the basic principles of learning.

LearnIng goaLs readIng aCTIvITIes

a. remember the key terms about classical conditioning. list all of the boldface words and write down their definitions.

b. apply the four steps of classical conditioning. Use the four steps of classical conditioning to describe how to train a horse to run at the sound of a bell. Hint: Horses naturally run when hit on the rump.

c. apply the concepts of acquisition, extinction, spontaneous recovery, generalization, and discrimination.

Extend these five concepts to the classical conditioning situation you described in part b.

d. analyze the acquisition of a phobia and counterconditioning to reduce a phobia.

Identify how a phobia of snakes can be acquired through classical conditioning and reduced through counterconditioning.

HOW DO WE lEarN BY ClaSSICal CONDITIONING? ■ 201

pavLov’s eXperIMenTs reveaL The FoUr sTeps In CLassICaL

CondITIonIng The Scientific Thinking feature on p. 202 describes classi- cal conditioning as revealed by Pavlov’s research. In addition, the Learning Tip on p.  203 will help you learn the four main terms associated with classical conditioning.

Classical conditioning always begins with a stimulus that naturally elicits a response. In other words, the stimulus produces the response, much like a reflex. In the case of Pavlov’s research, the presentation of food causes the salivary reflex and no learning is required to produce the salivation. As shown in Step 1 of the Scientific Thinking feature, Pavlov called the food the unconditioned stimulus (Us), because nothing is learned about the stimulus. Pavlov called the salivation elicited by food the unconditioned response (Ur). The response is “uncondi- tioned” because it is an unlearned behavior, like any simple reflex.

In Step 2, a neutral stimulus is presented. The neutral stimulus can be anything that the dog can see or hear, but it must not be associated with the UR. Pavlov used a metronome as the neutral stimulus. The metronome is a device that helps musi- cians keep time to music by making rhythmic clicking sounds, but it does not cause salivation.

Step 3 of the process is the conditioning trials. Now the neutral stimulus is presented along with the unconditioned stimulus that reliably produces the unconditioned response. Recall that the unconditioned stimulus here was the food, and the neutral stimulus was the clicking of a metronome. This is when the dog begins to associate the two stimuli, food and the clicking metronome, and we say the animal is learning.

In Step 4, the critical trials, we see evidence that the dog has learned the association between the food and the metronome. This is because presenting the clicking metronome alone, without the presence of the food, makes the dog salivate. We now say that the animal has been classically conditioned. At this point, the metronome is called the conditioned stimulus (Cs), because its clicking sound causes the dog to salivate only after the dog has gone through the process of conditioning. In our example, the dog has learned the relationship between the metronome and the food. Similarly, the salivation elicited by the metronome is now called the conditioned response (Cr), because it is a behavior that occurs only after conditioning. In this case, both the unconditioned and the conditioned

FIgUre 6.3 pavlov’s apparatus and Classical Conditioning (a) Ivan Pavlov, the white-haired man pictured here with his colleagues and one of his canine subjects, conducted groundbreaking work on classical conditioning. (b)  Pavlov’s apparatus collected and measured a dog’s saliva.

unconditioned stimulus (Us) a stimulus that elicits a response that is innate and does not require any prior learning.

unconditioned response (Ur) a response that does not have to be learned, such as a reflex.

conditioned stimulus (Cs) a stimulus that elicits a response only after learning has taken place.

conditioned response (Cr) a response to a conditioned stimulus; a response that has been learned.

(a)

3The dog was presented with a bowl that contained meat.

A tube carried the dog’s saliva to a container.

The container was connected to a device that measured the amount of saliva.

1 2

(b)

One-way window

Collecting tube from salivary glands

Measuring cup for saliva

Measuring device to record salivary �ow

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sCIenTIFIC ThInKIng: Pavlov’s Experiments Reveal Learning by Classical Conditioning

responses are salivation, but they are not identical. The conditioned response usually is weaker than the unconditioned response. Thus the metronome sound alone produces less saliva than the food does.

Now let’s go back to the scenario at the beginning of this section. As you watch the movie and see the woman descending into the basement in the middle of the night, you have a natural feeling of fear about this scary situation. In this case, the stimulus and your response to it are unconditioned. Now imagine a

Hypothesis: A dog can learn that a metronome predicts food.

Result: The conditioned response shows that the dog learned that the metronome predicted the arrival of food.

Conclusion: The dog was classically conditioned to associate the metronome with food. In other words, the dog salivated when hearing the sound of the metronome because it learned that the metronome predicted the arrival of food.

Question: Can you describe how it is beneficial for animals to learn that one thing predicts another? First consider an individual animal’s experience. Then consider how this learning might have been adaptive for the species.

1

Research Method:

Food (unconditioned stimulus) causes a re�exive response, salivation (unconditioned response).

The clicking metronome (neutral stimulus) does not cause the dog to salivate.

3

2

During conditioning trials, the clicking metronome is presented to the dog along with food so that the dog begins to learn the two stimuli are associated.

4 During critical trials, the clicking metronome (conditioned stimulus) is presented without the food, and the dog salivates (conditioned response).

US

US

CS

UR

No responseNeutral stimulus

CR

Neutral stimulus

After conditioning

Before conditioning

Conditioning

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In classical conditioning, the word conditioned simply means “learned,” as shown below.

LearnIng TIp: Understanding Classical Conditioning

when yoU see pLease ThInK MeanIng

Unconditioned stimulus Stimulus that is not learned Something that instinctively (innately) prompts a reaction

Unconditioned response response that is not learned reaction that is elicited instinctively (innately)

Conditioned stimulus Stimulus that is learned Something that prompts a reaction only after learning has occurred

Conditioned response response that is learned reaction that is elicited only after learning has occurred

kind of music begins to play in the movie. You first heard that music earlier in the movie, but you did not notice it very much. But now you realize that it seems to come on just before something bad happens to a character in the movie. You will probably start to feel tense as soon as you hear the music. You have learned that the music, the conditioned stimulus, predicts scenes where terri- ble things happen to the characters. This learning makes you feel tense as you watch the movie, because that feeling is the condi- tioned response (Figure 6.4).

Just as Pavlov’s studies revealed, the conditioned stimulus (music) produces a somewhat weaker, or slightly different, response than does the unconditioned stimulus (the scary scene). Because this association is learned, the conditioned response may be more a feeling of tension or anxiety than one of fear. But suppose you later hear this music in a different setting, such as on the radio. Again you will feel tense, even though you are not watching the movie. You have been classi- cally conditioned to feel anxious when you hear the music.

Learning Varies in Classical Conditioning  Like many other scientists of his time and in the decades since, Pavlov believed that conditioning is how animals adapt to their environments. By learning to predict what objects bring pleasure or pain—for instance, learning that the click- ing of a metronome predicts the appearance of food—animals acquire new adap- tive behaviors.

aCQUIsITIon The gradual formation of a learned association between a condi- tioned stimulus (here, a metronome) and an unconditioned stimulus (here, food) to produce the conditioned response (here, salivation) is known as acquisition (Figure 6.5a).

From his research, Pavlov concluded that for an animal to acquire a learned association, the two stimuli must occur at the same time. But later research has shown that the strongest conditioning occurs when the conditioned stimulus is presented slightly before the unconditioned stimulus. Thus, in the case of Pavlov’s dogs, if the metronome (CS) comes just before the food (US), this will produce a

FIgUre 6.4 Classical Conditioning in Thrillers In many suspenseful or scary movies, the soundtrack music becomes intense just before something exciting or terrible happens. The classic 1975 movie Jaws uses this classical conditioning technique to make us feel afraid, as the “duh-duh, duh- duh” theme music always plays just before the shark attacks. 

acquisition The gradual formation of an association between conditioned and unconditioned stimuli.

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stronger acquisition of a salivation response (CR) than if the metronome comes at the same time as, or after, the food. The metronome’s role in predicting the food is an important part of classical conditioning because it alerts the dog that food is coming. This process is even easier to understand in our movie example, where the music is setting you up to feel anxious just before you watch the woman go into the basement. The next time you watch a thriller, pay attention to the way the music gets louder just before a scary part begins, and notice how it makes you feel.

eXTInCTIon But what happens in this example if the food is never again presented with the metronome? In other words, once the salivation behavior (CR) is acquired, how long does it continue even without presentation of the food (US)? Animals sometimes have to learn when associations are no longer adaptive. Normally, after standard classical conditioning, the metronome (CS) leads to salivation (CR) because the animal learns to associate the metronome with the food (US). If the metronome is presented many times and food does not arrive, the animal learns that the metronome is no longer a good predictor of food. Because of this new learning, the animal’s conditioned salivary response to the metronome gradually disappears. This process is known as extinction. The conditioned response is extinguished when the conditioned stimulus is no longer paired with the arrival of the unconditioned stimulus (Figure 6.5b). Extinction is actually a form of learning that takes the place of the previous asso- ciation. Through extinction, the animal learns that the original association no longer holds true (Bouton, 1994; Bouton, Westbrook, Corcoran, & Maren, 2006).

2

(a) (b) (c) (d)

Drops of saliva elicited by CS

24-hour rest

24-hour rest

During acquisition, the CS-US pairings lead to increased learning. As a result, the CS can produce the CR.

If the CS is presented repeatedly without the US, eventually the CR is eliminated. This process is called extinction.

Later, if the CS is presented alone, it will produce a weak CR, known as spontaneous recovery.

This CR gets weaker with every spontaneous recovery and will eventually be extinguished if the CS is continually presented without the US.

First spontaneous recovery

Second spontaneous recovery

Number of trials

US CRCS CS No response No responseCS CR CS

2 4 6 8 10 12 14 16 18 20 22 2 4 6 8 2 4 6 8 0

5

10

15

Acquisition Extinction

FIgUre 6.5 acquisition, extinction, and spontaneous recovery Classical conditioning varies in strength and persistence, as shown by these three conditioning processes.

extinction a process in which the conditioned response is weakened when the conditioned stimulus is repeated without the unconditioned stimulus.

HOW DO WE lEarN BY ClaSSICal CONDITIONING? ■ 205

Although extinction reduces the strength of the associative bond, it does not completely eliminate that bond.

sponTaneoUs reCovery Imagine that a long time after extinction, the sound of the metronome is again presented. In this case, the most adaptive response by the dog is to see if the metronome will once again predict the arrival of food. When this occurs, the extinguished conditioned response of salivation is reactivated in a process called spontaneous recovery (Figure 6.5c). This recovery will fade quickly and lead to extinction once again, however, unless the CS is paired with the US again. Even a single presentation of the CS with the US will reestablish the CR, but the response will get weaker again if CS-US pairings do not continue (Figure 6.5d).

generaLIZaTIon, dIsCrIMInaTIon, and seCond-order CondI-

TIonIng In any learning situation, hundreds of possible stimuli can be associ- ated with the unconditioned stimulus to produce the conditioned response. How does the brain determine which stimulus is worth responding to? For instance, suppose we classically condition a dog so that it salivates (CR) when it hears a 1,000-hertz (Hz) tone (CS) that is paired with food (US). After the CR is established, the dog will also salivate when it hears tones close to 1,000 Hz. The farther the tones are from 1,000 Hz, the less the dog will salivate. stimulus generalization occurs when stimuli that are similar, but not identical, to the CS produce the CR. Generalization is adaptive, because in nature animals seldom repeatedly experience the CS in an identical way. Slight differences in background noise, temperature, lighting, and so on lead to slightly different perceptions of the CS. Thanks to these different perceptions, animals learn to respond to variations in the CS (Figure 6.6a–b).

Of course, generalization has limits. Sometimes it is important for animals to distinguish among similar stimuli. For instance, two plant species might look similar, but one of them might be poisonous. In stimulus discrimination, an animal learns to differentiate between two similar stimuli if one is consistently associated with the US and the other is not (Figure 6.6c). Pavlov and his students demonstrated that dogs could learn to make very fine distinctions between similar stimuli. You may have used stimulus discrimination to learn which ringtone or phone music belongs to which of your friends.

spontaneous recovery a process in which a previously extinguished response reemerges after the conditioned stimulus is presented again.

stimulus generalization learning that occurs when stimuli that are similar but not identical to the conditioned stimulus produce the conditioned response.

stimulus discrimination a differentiation between two similar stimuli when only one of them is consistently associated with the unconditioned stimulus.

FIgUre 6.6 stimulus generalization and stimulus discrimination Stimulus generalization and stimulus discrimination are important components of learning. These processes may take place even when a learned response has not been classically conditioned. (a) When people touch poison ivy and get an itchy rash, they learn to fear this three-leafed plant, and so they avoid it. (b) People may then experience stimulus generalization if they fear and avoid similar three-leafed plants—even nonpoisonous ones, such as fragrant sumac. By teaching people to avoid three-leafed plants, stimulus generalization therefore helps keep people safe. (c) People may also experience stimulus discrimination related to poison ivy. They do not fear and avoid dissimilar plants—such as Virginia creeper, which has five leaves and is nonpoisonous. If stimulus discrimination did not occur, fear of poison ivy would cause us to avoid activities near wooded areas, such as hiking and gardening.

(a)

(b)

(c)

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Now consider what might happen if another stimulus is added to the situa- tion. You know that in one of Pavlov’s early studies, a dog learned to associate a tone (CS) and food (US) so that the tone (CS) led to salivation (CR). In a second training session, a black square was repeatedly presented at the same time as the tone (CS). The dog salivated (CR) even though no food (US) was presented. After  a few trials, the black square was presented alone, and again the dog sali- vated (CR). In such cases, the first conditioned stimulus (the tone) became associated with another stimulus (the black square), which was then indirectly associated with the US (food). Effectively, the black square became the second conditioned stimulus (CS -2), which elicited the conditioned response of saliva- tion even when presented alone, without the US or the original CS. This phenom- enon is known as second-order conditioning.

Second-order conditioning helps account for the complexity of learned associa- tions, especially in people. For instance, suppose a child has been conditioned to associate money with desirable objects, such as candy and toys. Now suppose that whenever the child’s uncle visits, the uncle gives the child some money. Through second-order conditioning, the child will learn to associate the uncle with money. If the child feels affection for the uncle, some of that affection will come from the association with money (Domjan, 2003).

We Learn Fear Responses Through  Classical Conditioning Many people are afraid of certain things, but some people’s fears can get in the way of their daily functioning. For example, do you know anyone who is so afraid of spiders that he feels panicky when he even looks at a picture of one? Such extreme fear reactions, or phobias, may be the result of classical conditioning. A phobia is an acquired fear that is very strong in comparison to the real threat of an object or of a situation. Common phobias include the fear of heights, enclosed places, insects, snakes, or the dark. According to classical-conditioning theory, phobias develop through generalization of a fear experience, as when a person stung by a wasp develops a fear of all flying insects. (Phobias are discussed further in Chapter 14.)

The Case oF LITTLe aLBerT John Watson is known as the father of behavior- ism. He was one of the first researchers to demonstrate the role of classical condition- ing in the learning of phobias. In 1919, Watson asked a wet nurse at the Johns Hopkins clinic to let him use her son in what became a classic study. The study began when the boy, who became known as “Little Albert,” was 9 months old. Watson and his lab assistant presented Little Albert with various neutral objects, including a white rat, a rabbit, a dog, a monkey, costume masks, and a ball of white wool. Albert showed a natu- ral curiosity about these items, but he displayed no apparent emotional responses.

When Albert was 11 months old, the conditioning trials began. This time, as they presented the white rat and Albert reached for it, Watson smashed a hammer into an iron bar, producing a loud clanging sound (Figure 6.7). The sound scared the child, who immediately withdrew and hid his face. Watson did this a few more times, at intervals of five days, until Albert would whimper and cringe when the rat was presented alone. Thus the US (loud sound) led to a UR (fear). Eventually, the pairing of the CS (rat) with the US (loud sound) led to the rat alone produc- ing a CR (fear). The fear response generalized to other stimuli that Watson had

FIgUre 6.7 Case study of “Little albert” reveals phobias are Learned Through Classical Conditioning little albert learned to associate a white rat with a loud sound that made albert feel afraid. Eventually albert showed the conditioned fear response when he saw the white rat. This case study revealed that phobias could be learned through classical conditioning.

HOW DO WE lEarN BY ClaSSICal CONDITIONING? ■ 207

presented along with the rat at the initial meeting. Over time, Albert became frightened of them all, including the rabbit and the ball of wool. Even a Santa Claus with a white beard produced a fear response. Thus Watson demonstrated that phobias could be brought about by classical conditioning.

Though Albert was emotionally stable when the study began, and Watson believed the study would cause him little harm, Watson’s condi- tioning of Albert has long been criticized as unethical. Today an ethics committee probably would not approve such a study. Watson had planned a series of trials where he would continually present the feared items to Albert paired with more pleasant things, but Albert’s mother removed the child from the study before Watson could conduct the trials. Watson did not keep track of Albert, but various researchers have sought to identify him over the years (Griggs, 2015). According to the best available evidence, he was William Albert Barger, who died in 2007 at age 87 (Powell, Digdon, Harris, & Smithson, 2014; Figure 6.8). His relatives described him as easygoing, so he does not seem to have suffered long-term problems from being in the study. Barger was described as disliking animals, especially dogs, throughout his life and would cover his ears when he heard barking.

CoUnTerCondITIonIng A colleague of Watson’s—the behavioral pioneer Mary Cover Jones—did use this method successfully to reduce phobias. Jones eliminated the fear of rabbits in a 3-year-old by bringing a rabbit closer as she provided the child with a favorite food (Jones, 1924). Such classical-conditioning techniques have since proved valuable in developing very effective behavioral ther- apies to treat phobias. In the example above, where a person might have a phobia of spiders, a clinician might expose the client to spiders while having him engage in an enjoyable task. This technique, called counterconditioning, may help the client overcome the phobia.

The behavioral therapist Joseph Wolpe has developed a formal treatment based on counterconditioning (Wolpe, 1997). If you were undergoing Wolpe’s treatment, called systematic desensitization, first you would be taught how to relax your muscles. Then you would be asked to imagine the feared object or situation while you continued to use the relaxation exercises. Eventually, you would be exposed to the feared stimulus while relaxing. The general idea is that the CS S CR1 (fear) connection can be broken by developing a CS S CR2 (relaxation) connection. Psychologists now believe that in breaking such a fear connection, repeated expo- sure to the feared stimulus is more important than relaxation (as you will read about in Chapter 15).

Adaptation and Cognition Influence  Classical Conditioning Pavlov’s original explanation for classical conditioning was that any two events presented together would produce a learned association. In other words, any object or phenomenon could be converted to a conditioned stimulus when asso- ciated with any unconditioned stimulus. Pavlov and his followers believed that the strength of the association was determined by factors such as the intensity of

FIgUre 6.8 Little albert as an adult The best evidence indicates that Watson’s study participant little albert was William albert Barger, who lived to be 87.

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the conditioned and unconditioned stimuli. For example, a louder metronome or a larger piece of meat would produce stronger associations than a quieter metronome or a smaller piece of meat. In the mid-1960s, a number of challenges to Pavlov’s theory suggested that some conditioned stimuli were more likely to produce learning than others.

e vo LU T I o n a ry I n F LU e n C e s  Let’s return for a mom ent to the situation we used to open this chapter: your response to shrimp after your bad experience with it at the party. Such conditioned taste aversion is the result of clas- sical conditioning. We also saw conditioned taste aversion in the gray wolves of the Northern Rocky Mountain region that stopped preying on sheep after becoming ill from eating

poisoned sheep meat. In the case of the wolves, when the sheep carcass (CS) was paired with the poison (US), the wolves that ate the meat vomited. They associ- ated feeling sick with the sheep (CR), so it was adaptive for them to stop preying on the sheep (CR). However, research conducted by the psychologist John Garcia and colleagues showed that certain pairings of stimuli are more likely to become associated than others (Garcia & Koelling, 1966).

Conditioned taste aversions like these are easy to produce with smell or taste, but they are very difficult to produce with light or sound. This difference makes sense, because smell and taste are the main cues that guide an animal’s eating behavior. From an evolutionary viewpoint, animals that quickly associate a certain flavor with illness, and therefore avoid that flavor, will be better adapted. That is, they will be more likely to survive and pass along their genes.

However, auditory and visual stimuli may have survival value for particular animals in particular environments. Thus animals may learn adaptive responses that are related to the potential dangers associated with the stimuli. For example, monkeys can more easily be conditioned to fear snakes than to fear objects such as flowers or rabbits (Cook & Mineka, 1989). The psychologist Martin Seligman (1970) has argued that animals are genetically programmed, or biologically prepared, to fear specific objects. Preparedness helps explain why animals tend to fear potentially dangerous things (e.g., snakes, fire, heights) rather than objects that pose little threat (e.g., flowers, shoes, babies; Figure 6.9).

CognITIve InFLUenCes Until the 1970s, most learning theorists were behaviorists. They were concerned only with observable stimuli and observable responses. Since then, there has been more emphasis on trying to understand the mental processes that are the basis of conditioning. An important principle has emerged from this work: Classical conditioning is a way that animals come to predict the occurrence of events.

The psychologist Robert Rescorla (1966) conducted one of the first studies that highlighted the role of cognition in learning. He argued that for learning to take place, the conditioned stimulus must accurately predict the unconditioned stimulus. For instance, a stimulus that occurs before the US is more easily condi- tioned than one that comes after it. Even though both are close to the US in time, the stimulus that comes before the US is more easily learned because it predicts the US. We saw this effect in the example of creepy music before scary scenes in movies.

The cognitive model of classical learning states that an animal learns to expect that some predictors (potential CSs) are better than others. According to this

FIgUre 6.9 Fearing dangerous Things Is a helpful adaptive response This cat is showing a fear response to the dog. The tendency for animals and humans to fear dangerous things, such as predators and poisonous plants, makes sense. after all, being biologically prepared to fear potentially dangerous situations makes survival more likely.

HOW DO WE lEarN BY ClaSSICal CONDITIONING? ■ 209

CS US CR

CR

Neutral stimulus US

? ?

?

No response

CS US

A dog learns to associate an electric can opener (conditioned stimulus) with the arrival of food (unconditioned stimulus). This association causes the dog’s tail to wag (conditioned response).

1

The dog is surprised when a manual can opener (neutral stimulus) replaces the electric one. Because it is surprised, the dog does not show the conditioned response.

2

The dog now pays attention to the environment and so comes to associate the new can opener (conditioned stimulus) with the arrival of food (unconditioned stimulus). Now the manual can opener (new conditioned stimulus) becomes the better predictor of the expected event: food. As a result, the manual can opener elicits the conditioned response.

3 FIgUre 6.10 The role of Cognition in Learning The cognitive model of learning emphasizes the role of prediction and expectation in learning.

model, the strength of the CS-US association is determined by how unexpected or surprising the US is. When an animal encounters a new stimulus, it pays attention to it. The more surprising the US, the harder an animal tries to understand how it happened. Figuring out the US helps the animal predict when it will happen again. The result of this effort is greater classical conditioning of the new event (CS) that predicted the US.

Suppose you always use an electric can opener to open a can of dog food. Your dog associates the sound of the can opener (CS) with the appearance of food (US). The dog has the conditioned response (CR) of wagging its tail when it hears that sound. Now say the electric can opener breaks, and you replace it with a manual one. According to the cognitive model of learning, the unexpected appearance of the food (US) without the electric can opener sound (CS) will cause your dog to pay attention to events in the environment that might have produced the food. Soon the dog will learn to associate being fed with use of the new can opener (new CS; Figure 6.10).

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6.3  How Do We Learn by Operant Conditioning ?

operant conditioning a learning process in which the consequences of an action determine the likelihood that the action will be performed in the future.

LearnIng goaLs readIng aCTIvITIes

a. remember the key terms about operant conditioning. list all of the boldface words and write down their definitions.

b. Understand the four types of reinforcement and punishment in operant conditioning.

Summarize in your own words the four ways that reinforcement and punishment affect behavior.

c. apply the four schedules of reinforcement. Provide an example of each of the four schedules of reinforcement in your life.

d. apply the three cognitive aspects of conditioning. Describe an example from your own life of learning via a cognitive map, latent learning, and insight.

■ In Pavlov’s classical conditioning, a conditioned stimulus that is predictably associated with an unconditioned stimulus produces a learned, conditioned response.

■ Six factors affect the strength and persistence of learning from classical conditioning.

■ Phobias may develop when classical conditioning leads to generalization of a fear experience. Techniques based on classical conditioning, such as counterconditioning, can be used to treat phobias.

■ Classical conditioning helps animals learn responses that aid survival. The cognitive model states that the amount of conditioning that occurs is determined by how unexpected or surprising the unconditioned stimulus is.

6.2 CheCKpoInT: How Do We Learn by Classical Conditioning ?

You know that if you study, you’re likely to get a better grade on an exam. That seems like an obvious connection, but how did you learn this association? Not through classical conditioning. That form of conditioning is a relatively passive process. For example, an animal learns predictive connections between stimuli, no matter what the animal does. So when we look at an example of classical conditioning, we cannot conclude that learning to behave in a certain way has occurred because of the consequences of the animal’s action.

However, our behaviors often represent the way to reach a desired outcome. These behaviors are instrumental—they are done for a purpose. We study to get good grades, we eat our favorite dessert because it tastes delicious, and so on. We learn that behaving in certain ways leads to positive outcomes and behaving in other ways results in negative outcomes, and this knowledge affects how we act in the future. This type of associative learning, where we learn the relationship between a behavior and its consequences, and the relationship affects our future actions, is called operant conditioning.

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Animals Learn Through the Outcomes   of Their Actions Research on how animals learn the effects of an action began in the late nineteenth century, in Cambridge, Massachusetts, at the home of the psychologist William James. A young graduate student named Edward Thorndike was working with James. Thorndike performed the first reported carefully controlled experiments in comparative animal psychology. Specifically, he studied whether nonhuman animals showed signs of intelligence.

ThorndIKe’s eXperIMenTs reveaL The eFFeCTs oF aCTIon To conduct his research, Thorndike built a puzzle box—a small cage with a trapdoor (Figure 6.11a). The trapdoor would open if the animal inside performed a specific action, such as pulling a string. Thorndike placed food-deprived animals, at first chickens but later cats, inside the puzzle box to see if they could figure out how to escape.

To motivate the cats, Thorndike placed food just outside the box (Figure 6.11b, Step 1). When first placed in the box, the cat usually made several unsuccessful attempts to escape. After 5 to 10 minutes of struggling, the cat would accidentally step on the lever that pulled the string, and the door would open (see Figure 6.11b, Step 2). Thorndike would then return the cat to the box and repeat the trial. During each of the following trials, the cat more and more quickly pushed the lever. Soon it learned to escape from the puzzle box within seconds (see Figure 6.11b, Step 3). Thorndike’s research led him to develop a general theory of learning. According to this law of effect, any behavior that leads to a “satisfying state of affairs” is likely to occur again. Any behavior that leads to an “annoying state of affairs” is less likely to occur again.

The cat is placed in the box. Food is placed outside where the cat can see it.

The cat is put back in the box. It more quickly presses the lever to get out.

3After several attempts to get out, the cat accidentally presses the lever. The door opens, and the cat eats.

21

(b)

Trapdoor

String

Lever

(a)

FIgUre 6.11 Thorndike’s puzzle Box (a) Thorndike’s experiments used puzzle boxes, like the one shown here. (b) The box was designed to assess learning in animals, and Thorndike used it in developing the law of effect. Because stepping on the lever to pull the string led to the satisfying state where the cat could escape from the box, the cat stepped on the lever more quickly the next time it was in the box.

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Learning Varies in Operant Conditioning B. F. Skinner developed a more formal learning theory based on the law of effect. Skinner, the psychologist most closely associated with operant conditioning, chose the term operant to express the idea that animals operate on their environments to

produce effects. Operant conditioning is the learning process in which an action’s consequences determine how likely that action is to be performed in the future. Skinner also coined the term reinforcer to describe a stimulus that occurs after a response and increases the likelihood that the response will be repeated. Skinner believed that behavior—studying, eating, driving on the proper side of the road, and so on—occurs because it has been reinforced.

To test his theory, Skinner developed a simple device that is now known as a Skinner box. Inside the box, a lever that can be pressed (operant) is connected to a food supply (reinforcer). An animal, usually a rat or pigeon, is placed in the Skinner box. Through operant conditioning, the animal learns that pressing

the lever results in food (Figure 6.12).

shapIng In operant conditioning, providing the reinforcer before the animal displays the appropriate behavior usually does not lead to learning. Inside a Skin- ner box, an animal has so little to do that it usually makes the right correct response: It presses the lever or key fairly quickly. Outside a Skinner box, however, the same animal might be distracted and take longer to perform the action you are looking for. Rather than wait for the animal to spontaneously perform the action, you can use an operant- conditioning technique to teach the animal to do so. This power- ful process, called shaping, consists of reinforcing behaviors that are increasingly similar to the desired behavior.

For example, suppose you are trying to teach your dog to roll over. At first, you reward the dog for any behavior that even slightly resembles rolling over, such as lying down. Once this behavior is established, you selectively reinforce it. That is, you reward the dog each time it gets closer to performing the behavior you want. For instance, you might reward the dog for rolling onto one side. Next you might reward it for lying on its back. This system eventually produces the desired behavior as the animal learns what behavior is being reinforced. Indeed, shaping has been used to condition animals to perform amazing feats: pigeons playing table tennis, dogs playing the piano, pigs doing housework such as pick- ing up clothes and vacuuming, and so on (Figure 6.13).

FIgUre 6.13 shaping The operant conditioning technique of shaping consists of reinforcing behaviors that are increasingly similar to the desired behavior. Shaping can be used to train animals to perform unusual behaviors.

If you are trying to teach your dog to surf, you first reward the dog for approaching the surfboard.

1 Then you reward the dog for getting on the surfboard and standing there.

2 Then you reward the dog for continuing to stand on the board as the waves move it.

3 As the dog learns what behavior is being reinforced, it eventually learns to produce the desired behavior: surfing!

4

Lever

Food tray

FIgUre 6.12 skinner Box In B. F. Skinner’s research, an animal received a reinforcer, such as food, after pressing a lever (operant). Getting the food made the animal more likely to repeat that action. learning a response in this way is called operant conditioning.

HOW DO WE lEarN BY OPEraNT CONDITIONING? ■ 213

Shaping has also been used to teach people. People with psychological dis orders can learn appropriate social skills, children with autism spectrum disorder can learn language, and individuals with differences in developmental abilities can learn life skills. More generally, parents and educators often use shaping to encourage appropriate behavior in children. For example, they praise children for their first, often unreadable, attempts at handwriting.

reInForCers Can Be CondITIoned The most obvious reinforcers are those necessary for survival, such as food or water. Because they satisfy biological needs, they are called primary reinforcers. From an evolutionary standpoint, the learning value of primary rein forcers makes a great deal of sense: Animals that repeatedly perform behaviors that are reinforced by food or water are more likely to survive and pass along their genes.

Many apparent reinforcers do not directly satisfy biological needs, however. Receiving a grade of A on your term paper, a compliment on your art project, or a raise at work can all be reinforcing. Events or objects that serve as reinforcers but do not satisfy biological needs are called secondary reinforcers. These reinforc- ers are established through classical conditioning. We learn to associate a neutral stimulus, such as money, with a primary reinforcer such as food (US). Money is really only pieces of metal or slips of paper, but these and other neutral objects become meaningful conditioned stimuli (CS) thanks to their associations with unconditioned stimuli.

reInForCer poTenCy Some reinforcers are more powerful than others. The psychologist David Premack (1959; Holstein & Premack, 1965) theorized about how a reinforcer’s value could be determined. The key is the amount of time an animal, when free to do anything, engages in a specific behavior associ- ated with the reinforcer. For instance, given freedom of choice, children more often eat ice cream than spinach. Ice cream is therefore more rein- forcing for children than spinach is. One great advantage of Premack’s theory is that it can account for differences in individual peoples’ values. For people who eat ice cream more often than spinach, ice cream serves as a stronger reinforcer.

A logical application of Premack’s theory, called the Premack principle, is that a more valued activity can be used to reinforce the performance of a less valued activity. When parents tell their children, “Eat your spinach and then you’ll get dessert,” they’re using the Premack principle. You’ve probably used it on yourself a few times: “After I finish reading this chapter, I’ll watch that video” (Figure 6.14).

FIgUre 6.14 The premack principle in our daily Lives When you were younger, did you have to eat your dinner before you got your dessert? If so, then you experienced the Premack principle firsthand. In this case, you had to accept the less desired food in order to receive the food you really wanted.

Try IT yoUrseLF: Use Operant Conditioning to Change a Behavior

If you have a pet, you might want to train it to perform a behavior. let’s say you want your pet to turn around in circles. You can use operant conditioning to encour- age or increase that behavior. First, decide what type of reinforcement to use. (Don’t use punishment, because that decreases a behavior.) a favorite treat usually works best. Then choose an appropriate schedule of reinforce- ment (see Figure 6.16). Try it and see if it works!

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Reinforcement and Punishment Influence  Operant Conditioning  Reinforcement and punishment have opposite effects on behavior. Reinforcement makes a behavior more likely to be repeated, and punishment makes that behavior less likely to occur again. Furthermore, in both positive reinforcement and posi- tive punishment, a stimulus is added. But in negative reinforcement or negative punishment, a stimulus is removed. The operant conditioning terminology can be confusing, so let’s look at each of these concepts next. Figure 6.15 also gives an overview of all these situations, and the Learning Tip will help you remember the terms correctly.

posITIve and negaTIve reInForCeMenT Both positive and negative reinforcement increase the likelihood of a certain behavior. positive reinforce- ment is the addition of a stimulus that increases the probability that a behavior will be repeated. Positive reinforcement is often called reward, and when behav- iors are rewarded, the actions increase in frequency. For example, feeding a rat after it presses a lever will increase the probability that the rat will press the lever again (see Figure 6.15a). Similarly, when you receive praise from your boss or an increase in pay, your response is to work harder. In contrast, negative reinforce- ment increases behavior by removing a stimulus. Negative reinforcement occurs when a rat presses a lever to turn off a painful electric shock. The rat will be more likely to press the lever again in the future (see Figure 6.15b). However, be aware that negative reinforcement is not the same as punishment.

Negative reinforcement is common in everyday life. You take a pill to get rid of a headache. You close your door to shut out noise. You change the channel to avoid watching an awful show. You pick up a crying baby. In each case, you are trying to stop a stimulus. If the action you take successfully reduces the stimulus, then the next time you have a headache, hear noise in your room, see an awful program, or are with a crying baby, the more likely you are to repeat the behavior that reduced the stimulus. Your behavior has been negatively reinforced.

Note, however, that while picking up the crying infant is negatively reinforcing for you, it positively reinforces the infant for crying! The infant learns that crying

positive reinforcement The addition of a stimulus to increase the probability that a behavior will be repeated.

negative reinforcement The removal of a stimulus to increase the probability that a behavior will be repeated.

positive punishment The addition of a stimulus to decrease the probability that a behavior will recur.

negative punishment The removal of a stimulus to decrease the probability that a behavior will recur.

POSITIVE (Add stimulus)

NEGATIVE (Remove stimulus)

Negative reinforcement: When the lever is pressed,

a shock is removed.

Positive reinforcement: When the lever is pressed,

food is given.

Positive punishment: When the lever is pressed,

a shock is given.

low high

Negative punishment: When the lever is pressed,

food is removed.

REINFORCEMENT (Increases behavior)

PUNISHMENT (Decreases behavior)

(a) (b)

(c) (d)

low high

FIgUre 6.15 reinforcement and punishment This graphic will help you understand the four types of reinforcement and punishment.

HOW DO WE lEarN BY OPEraNT CONDITIONING? ■ 215

increases the likelihood of being picked up and comforted. Likewise, a parent who gives a child candy to stop a tantrum is negatively reinforced (the tantrum stops), but the child is positively reinforced to have more tantrums in the future.

posITIve and negaTIve pUnIshMenT By con- trast, both positive and negative punishment reduce the like- lihood that a behavior will be repeated. positive punishment is when the addition of a stimulus decreases the probabil- ity of a behavior being repeated. This happens when a rat receives an electric shock for pressing a lever, which makes it less likely to press the lever again (see Figure 6.15c). If a teenager gets a speeding ticket, then she has experienced positive punishment, which should make her less likely to speed in the future. However, by removing a stimulus, nega- tive punishment decreases the likelihood a behavior will be repeated. For example, when a rat presses a lever and food is removed, the rat is not likely to press the lever again (see Fig- ure 6.15d). And when a teenager loses driving privileges for speeding, he has received negative punishment that should prevent speeding in the future. As these examples show, negative and positive forms of punishment should produce the same result: The teen will be less likely to speed the next time he or she gets behind the wheel.

sChedULes oF parTIaL reInForCeMenT How often should a rein- forcer be given? To produce fast learning, behavior might be reinforced each time it occurs. This process is known as continuous reinforcement. In the real world, behavior is seldom reinforced continuously. Animals do not find food each time they look for it, and people do not receive praise each time they behave acceptably. Instead, occasional re inforcement of behavior is more common. This is called partial reinforcement.

The effect of partial reinforcement on conditioning depends on the rein- forcement schedule. Partial reinforcement can be given on a predictable basis, which is called a fixed schedule, or on an unpredictable basis, called a variable schedule. Partial reinforcement can also be given based on either the passage of time, called an interval schedule, or the number of behavioral responses, called a ratio schedule. Crossing how reinforcement is given with how consistently it is given provides the four most common schedules of reinforcement, as shown in Figure 6.16 and in the Learning Tip on p. 217.

Many jobs pay employees on a fixed interval schedule (FI), where reinforce- ment is given after a fixed amount of time has passed. For example, say people earn $10 for each hour they work. One feature of fixed interval schedules is a scalloping pattern. “Scalloping ” refers to a series of circle segments that look like the edge of a scallop shell. The rises in this pattern mean that behavior continually increases just before the opportunity for reinforcement, and then behavior drops off after reinforcement (see Figure 6.16a). You’re probably familiar with this pattern in your courses that have regularly scheduled examinations. Students often slack off a bit after an exam and then “cram” their studying into the time just before the next exam.

variable interval schedules (vI) provide reinforcement after an unpredict- able amount of time has passed. A good example of a VR schedule is the pop quiz schedule, in which students know that they could face a quiz at any time

It’s easy to remember the difference between the four types of reinforcement and punishment: positive reinforcement, negative reinforcement, positive punishment, and negative punishment. ask these two questions to get it right:

1. Is a stimulus added or taken away? ■ If a stimulus is added, then this is “positive.” ■ If a stimulus is taken away, then this is “negative.”

2.  after adding or taking away a stimulus, does the behavior increase or decrease?

■ If the behavior increases, then this is “reinforcement.” ■ If the behavior decreases, then this is “punishment.”

If you put together the two words from your answers to questions 1 and 2, you will know which of the four types of reinforcement and punishment is being used.

LearnIng TIp: Four Types of Reinforcement and Punishment

fixed interval schedule (FI) reinforcing the occurrence of a particular behavior after a predetermined amount of time since the last reward.

variable interval schedule (vI) reinforcing the occurrence of a particular behavior after an unpredictable and varying amount of time since the last reward.

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(see  Figure  6.16b). As you might guess, VR schedules lead to more consistent response rates than FI schedules. In a class with pop quizzes, you cannot slack off in studying, because you need to be ready for a quiz at any time.

By contrast, in a fixed ratio schedule (Fr), reinforcement is given after a fixed number of responses—for instance, a system that pays a factory worker by the piece or a coffee card rewards program that gets you a free cup of coffee after you buy 10 cups (see Figure 6.16c). Fixed ratio schedules often elicit more robust responding than FI schedules. For example, factory workers paid by the piece are usually more productive than those paid by the hour, especially if the workers receive incentives for higher productivity.

variable ratio schedules (vr) provide reinforcement after an unpredictable number of responses. An example is slot machines: They may pay out a consistent amount over the long term, but you never know which pull of the handle will result in winning money (see Figure 6.16d).

Besides affecting the number of responses, the schedule of reinforcement also affects how long a behavior persists. Continuous reinforcement is highly effective for teaching a behavior. If the reinforcement is stopped, however, the behavior is quickly extinguished. For instance, normally when you put money in a vending machine, it gives you a product in return. If it fails to do so, you quickly stop putting your money into it. By contrast, at a casino you might drop a lot of money into a slot machine that rarely rewards you with a jackpot. Psychologists explain this persis- tent behavior as the effect of a variable ratio schedule of reinforcement: People put money in slot machines because the machines sometimes provide monetary rewards.

The partial-reinforcement extinction effect says that behavior goes on longer under partial reinforcement than it does under continuous reinforcement. During continuous reinforcement, the learner easily can detect when reinforcement has stopped. But when the behavior is reinforced only some of the time, the learner needs to keep repeating the behavior over time to notice the absence of reinforce- ment. Thus, when reinforcement is less frequent during training, the behavior

fixed ratio schedule (Fr) reinforcing a particular behavior after that behavior has occurred a predetermined number of times.

variable ratio schedule (vr) reinforcing a particular behavior after the behavior has occurred an unpredictable and varying number of times.

partial-reinforcement extinction effect The greater persistence of behavior under partial reinforcement than under continuous reinforcement.

Variable ratio: “Slot machine schedule,” which produces robust responding because gamblers never know how many times they must pull the lever before winning. The reinforcer (slash mark) is winning.

Fixed ratio: “Coffee card schedule,” which produces consistent responding and then a small burst of responding as a person gets close to earning a free cup of coffee. The reinforcer (slash mark) is the free cup of coffee.

Variable interval: “Pop quiz schedule,” where students must study more regularly for an unscheduled quiz. The reinforcer (slash mark) is the quiz grade.

Fixed interval: “Cramming schedule,” where students procrastinate studying for a scheduled exam as long as possible and then study a lot just before the exam. The reinforcer (slash mark) is the exam grade.

(a) (b) (c) (d)

FI VIMany

Few

Cumulative responses

FR

TimeTimeTime

VR

Time

FIgUre 6.16 effect of reinforcement schedules on Behavior The curves show cumulative responses under different schedules of reinforcement over time. The steeper the line, the greater the response rate.

HOW DO WE lEarN BY OPEraNT CONDITIONING? ■ 217

is more resistant to extinction. To condition a behavior so that it persists, you need to reinforce it continuously when it is first being learned and then slowly change to using partial reinforcement. Parents naturally follow this strategy in teaching their children behaviors such as toilet training.

The persistence of partially reinforced behaviors also provides an important lesson for trying to extinguish unwanted behaviors. For instance, suppose your cat meows when demanding to be fed. You try to ignore it, because you don’t want to reinforce the behavior. But once in a while, you break down and feed the cat. You’ve just made it even harder to extinguish the behavior. The longer you take to break down, the more persistent the cat will be. To extinguish the behavior, you have to consistently withhold reinforcement. The same is true for a child who demands a candy bar at the grocery store. To stop the child from making demands, you refuse to buy the candy bar. Then, any other time the child demands that you buy an item, you refuse again and again.

Operant Conditioning Affects Our Lives Now imagine that a child demands a candy bar at a grocery store, the parent says no, and the child throws a temper tantrum. The exasperated parent yells, “If you don’t stop screaming, you’re going to get a smacked bottom!” Will this approach produce the desired behavior?

parenTaL pUnIshMenT Is IneFFeCTIve To make their children behave, parents sometimes use punishment as a means of discipline. Many contemporary psychologists believe that punishment is often applied ineffectively, and that it may have unintended and unwanted consequences. Research has shown that for punishment to be effective, it must be reasonable, unpleasant, and applied immedi- ately so that the relationship between the unwanted behavior and the punishment is clear (Goodall, 1984; O’Leary, 1995). Obviously, this means there is considerable potential for confusion.

Sometimes punishment is wrongly applied after a behavior that is actually desirable. For example, if a student is punished after admitting to cheating on an exam, he may then associate the punishment with being honest rather than with the original offense. As a result, the student learns not to tell the truth. As Skin- ner once pointed out, one thing people learn from punishment is how to avoid it. Rather than learning how to behave appropriately, they may learn not to get caught.

Punishment can also lead to negative emotions, such as fear and anxiety. Through classical conditioning, these emotions may become associated with the person who administers the punishment. If a child learns to fear a parent or teacher, the long-term relationship between child and adult may be damaged (Gershoff, 2002).

In addition, punishment often fails to offset the reinforcing aspects of the undesired behavior. In real life, any behavior can be reinforced in multiple ways. For instance, thumb sucking may be reinforced because it makes a child feel good,

It’s easy to remember the difference between the four schedules of reinforcement: fixed interval, variable interval, fixed ratio, and variable ratio. ask these two questions to get it right:

1. Is the schedule predictable, or does it change? ■ If the schedule is predictable, then it is “fixed.” ■ If the schedule changes, it is “variable.”

2. Does the schedule refer to the amount of time that has passed or the number of responses that have occurred? ■  If the schedule refers to the passage of time, then it

is “interval.” ■  If the schedule refers to the number of responses,

then it is “ratio.”

Put together the two words from your answers to questions 1 and 2, and you will know which of the four types of reinforcement schedules is being used.

LearnIng TIp: Four Schedules of Reinforcement

218 ■ ChapTer 6 lEarNING

because it provides relief from negative emotions, and because it eases hunger. Punishment may not be enough to offset such rewards, and it may reinforce the child’s secrecy about thumb sucking.

For these and other reasons, most psychologists agree with Skinner’s recom- mendation that reinforcement is a better way than punishment to teach desir- able behavior (Figure 6.17). A child complimented for being a good student is likely to perform better academically than one punished for doing poorly. After all, reinforcing good behavior tells the child what to do. Punishing the child for bad behavior does not tell the child how to improve.

One form of punishment that most psychologists believe is especially inef- fective is physical punishment, such as spanking (see the Being a Critical Consumer feature in Chapter 1). Even so, spanking is very common. Nearly three-quarters of American parents spank their children and apparently believe it is effective (Gallup, 1995; Lansford et al., 2010). As noted by Alan Kazdin and Corina Benjet (2003), beliefs about the appropriateness of spank- ing are related to religious beliefs, cultural views, and legal issues. Many coun- tries (e.g., Austria, Denmark, Israel, Sweden, and Italy) have banned physical punishment in homes or schools. Even the United Nations has passed resolu- tions discouraging it.

Researchers have provided evidence of many negative outcomes associated with spanking, especially severe spanking (Bender et al., 2007). These problems include poor parent/child relations, weaker moral values, mental health prob- lems, increased delinquency, and future child abuse. One concern is that physical punishment teaches the child that violence is an appropriate behavior for adults. We discuss such imitative behavior later in this chapter.

How often do mild forms of spanking cause problems? That question is open to debate (Baumrind, Larzelere, & Cowan, 2002), but the evidence indicates that other forms of punishment, such as taking away cell phone or Internet access, are more effective for decreasing unwanted behaviors (Kazdin & Benjet, 2003). Many psychologists believe that any form of punishment is less effective than using posi- tive reinforcement to increase the likelihood of engaging in “better” behaviors. By rewarding the behaviors they wish to see, parents are able to increase those behav- iors while building more positive bonds with their children.

BehavIor ModIFICaTIon Behavior modification is the use of operant- conditioning techniques to eliminate unwanted behaviors and replace them with desirable ones. The general reasoning behind behavior modification is that most unwanted behaviors can be unlearned. Conditioning strategies are widely used, for example, to teach people to be more productive at work, to save energy, and to drive more safely. Children with severe learning disabilities can be trained to communi- cate and to interact. As we discuss in Chapter 15, operant conditioning techniques are also effective for treating many psychological conditions.

One widespread behavior modification method draws on the principle of secondary reinforcement. Chimpanzees can be trained to perform tasks in exchange for tokens, which they can later trade for food. The tokens thus reinforce behavior, and the chimps work as hard to obtain the tokens as they work to obtain food. Prisons, mental hospitals, schools, and classrooms often use token economies, in which people earn tokens for completing tasks and lose tokens for behaving badly. The people can later trade their tokens for objects or privileges (Figure 6.18). Here, the rewards not only reinforce good behavior but also give participants a sense of control over their environment.

FIgUre 6.18 Token economies Change Behavior Many teachers give tokens (or stickers or pencils) for obeying class rules, turning in homework on time, and helping others. at some future point, the tokens can be exchanged for rewards, such as fun activities or extra recess time.

FIgUre 6.17 parents should avoid the Use of punishment In general, using reinforcement to improve children’s behavior is more effective than using punishment. In reinforcing children’s behavior, it is especially important to say what they should be doing instead of what they should not be doing.

The Centers for Disease Control and Prevention report that less than half of adults meet the goal of exercising 30 minutes a day, 5 days per week (U.S. DHHS, 2008). Maybe you intend to exercise daily, but then struggle to find the time to get to the gym. Or maybe you make working out a priority for a few weeks and then stop. How can psychology help you stick with your exercise program?

Just as psychologists use operant conditioning to change the behav- iors of animals, including humans, you can condition yourself to perform healthful behaviors. Consider these steps:

1. Identify a behavior you wish to change. First, you need to decide what behavior you wish to modify. In this case, you want to increase your level of physical activity.

2. set goals. Set goals that are realistic, specific, and measurable. If your current exercise program consists of a daily race to beat the closing eleva- tor door, setting a goal to run 10 miles per day every day this month is not realistic. a goal of “exercise more” is too vague. Instead, set a goal that you can accomplish in a relatively short time, and one you can measure objectively. For example: Walk up the three flights of stairs at work at least four days this week; or attend three yoga sessions this week; or walk at least 10,000 steps each day this week. Setting goals you can meet quickly allows for more opportunities for reinforcement. If your ultimate goal is to have 30 minutes of moderate exercise 5 days per week, you need to set small, incremental subgoals that you can reinforce along the way.

3. Monitor your behavior. Monitor your behavior for a week before you begin your new physical activity regimen. This will likely move you toward your goal, since you will be more conscious of your behavior. It will also give you a baseline against which you can measure your prog- ress. record your observations. If you have a smartphone, you might download an app for recording physical activity. Or you can register at an exercise-tracking Web site. Or just use a paper notebook.

4. select a reinforcer and decide on a reinforcement schedule. When you choose a reinforcer, pick something attainable that you genuinely find enjoyable. For example, perhaps for every yoga class you attend, you will earn one song from iTunes. Or you could give yourself a penny for every hundred steps you take each day. later, when the money adds up, you can use it to buy something you do not normally spend money on.

5. reinforce the desired behavior. To bring about the behavior change you want to see, you need to reinforce the desired behavior whenever it occurs. Be consistent. Suppose that if you work out at the gym three times this week, you treat yourself to a movie. This is important: If you do not work out at the gym three times this week, do not go to the movie. You may be tempted to go anyway, but if you want the behavior modification to work, you have to resist. If you do not behave appropri- ately, you do not receive the reinforcer. allow yourself no exceptions.

6. Modify your goals, reinforcements, or reinforcement schedules, as needed. Once you begin consistently hitting your stated goals, make the goals more challenging. add more days of exercise per week, more minutes, or more reps per workout. If you find yourself getting bored with a reinforcer, mix it up a bit. Just be sure to select reinforcers that are genuinely appealing. and change the reinforcement schedule so you have to work harder to get the reward—for example, delay the reinforcement until you’ve completed two workouts rather than one.

Of course, you can use these principles to address other behaviors, such as procrastinating on your studies, neglecting to call your family, spending too much time on Facebook, and so on. For now, just pick one behavior you want to modify and try following the steps described. Once you get the hang of it, see if you can translate these steps to other areas of your life. You might amaze yourself with the power of behavior modification.

UsIng psyChoLogy

In yoUr LIFe:

Can Behavior Modification Help You Exercise Regularly?

220 ■ ChapTer 6 lEarNING

Biology and Cognition Influence   Operant Conditioning  Behaviorists such as B. F. Skinner believed that all behavior could be explained by straightforward conditioning principles. In reality, as described in this section, reinforcement explains only certain human behaviors. On the one hand, biologi- cal factors can either increase the effects of reinforcers or limit their effects on learning. On the other hand, reinforcement does not always have to be present for learning to take place.

dopaMIne aCTIvITy aFFeCTs reInForCeMenT Recall that Skinner and other traditional behaviorists defined reinforcement strictly in terms of whether it increased behavior. They were uninterested in why it increased behav- ior—whether any personal feelings might be involved, for instance. After all, they believed that mental states were impossible to study empirically.

Studies of learning have made it clear, however, that positive reinforce- ment works in two ways: It provides the subjective experience of pleasure, and it increases the desire for the object or event that produced the pleasure. If you behave in a way that produces a favorable outcome—for instance, studying for an exam and then getting an A—the experience creates responses in the brain that support studying for exams again.

Both the liking and wanting involved in positive reinforcement are a result of biological factors, particularly the neurotransmitter dopamine (Schultz, 2010; Wise & Rompre, 1989; Volkow, Wang, & Baler, 2011). When hungry rats are given food, they experience increased dopamine release in the regions of the brain that process reward information: the greater the hunger, the greater the dopamine release (Rolls, Burton, & Mora, 1980). Food tastes better when you are hungry, and water is more rewarding when you are thirsty, because more dopamine is released when you have been deprived.

In operant conditioning, dopamine has a biological influence on how reinforc- ing something is. Drugs that block dopamine’s effects disrupt operant condi-

tioning. On the other hand, drugs that enhance dopamine activation, such as cocaine and amphetamines, increase the reinforcing value of stimuli. As you learned in Chapter 3, this effect helps explain why dopamine is involved in addictive behavior, especially in terms of increased desire for the addictive substance.

BIoLogy ConsTraIns reInForCeMenT Though behavior can be shaped through reinforcement, we now know that animals have a hard time learning behaviors that run counter to their evolutionary adaptation. A good example of such biological constraints comes from the experience of Marian and Keller Breland. These psychologists used operant-conditioning tech- niques to train animals for commercials (Breland & Breland, 1961). Many of

their animals refused to perform certain tasks they had been taught. For instance, a raccoon learned to place coins in a piggy bank, but eventu- ally it refused to perform this task. Instead, the raccoon stood over the

piggy bank and briskly rubbed the coins in its paws. This rubbing behav- ior was not reinforced; in fact, it delayed reinforcement. One explanation for the raccoon’s behavior is that the task it was supposed to perform was incompatible with its innate, biologically determined, adaptive behaviors. The raccoon associ- ated the coin with food and treated it the same way: Rubbing food between the paws is hardwired for raccoons (Figure 6.19).

FIgUre 6.19 Biology Constrains Learning Through operant Conditioning animals have a hard time learning behaviors that go against their biological predispositions. For example, raccoons are hardwired to rub food between their paws, as this raccoon is doing. They have trouble learning not to rub objects.

Conditioning is most effective when the association between the response and the reinforcement is consistent with the animal’s built-in biological predisposi- tions. For instance, the psychologist Robert Bolles has argued that animals have built-in defense reactions to threatening stimuli (Bolles, 1970). Pigeons can be trained to peck at keys to obtain food or secondary reinforcers, but it is difficult to train them to peck at keys to avoid electric shock. They can learn to avoid shock by flapping their wings, however, because wing flapping is their natural means of escape.

LearnIng wIThoUT reInForCeMenT Another challenge to the idea that reinforcement is responsible for all behavior is the fact that learning can take place without reinforcement. Edward Tolman, an early cognitive theorist, argued that reinforcement has more impact on performance than on acquisition of knowledge through learning.

Tolman’s research investigated the answer to this question. In his experiments, rats had to learn to run through complex mazes to obtain food. Tolman believed that each rat developed a cognitive map. That is, during an experiment, each rat held in its brain a representation of the particular maze. That representation was based on the things and spaces the rat had seen inside the maze. The rat used this knowledge of the environment to help it find the food quickly.

To test his theory, Tolman and his students studied three groups of rats (Figure 6.20). The rats in Group 1 traveled through the maze, but received no reinforcement: They reached the “goal box,” but found no food in the box. On later trials, rats continued to wander through the maze slowly, making many “wrong turns” on the way to the goal box. The rats in Group 2 received reinforcement on every trial because there was food in the goal box. On each of the following trials, these rats found the box faster and with fewer errors. The rats in Group 3 started receiving reinforcement only after the first 10 trials. For the first 10 days, they performed as slowly and incorrectly as the unrewarded rats in Group 1. But the rats in Group 3 showed something amazing when they received their first reward on day 11. Suddenly, these rats very quickly and accurately navigated the maze to get to the goal box. In fact, they performed even better than rats in Group 2 that had been rewarded regularly (Tolman & Honzik, 1930).

Tolman’s results suggest that the third group of rats had learned a cognitive map of the maze all along. However, based on their performance once the re inforcement began, the Group 3 rats did not use that map to reveal their learning until they started being rewarded. In other words, they were learning even without reinforcement, a situation Tolman termed latent learning. The

HOW DO WE lEarN BY OPEraNT CONDITIONING? ■ 221

cognitive map a visuospatial mental representation of an environment.

latent learning learning that takes place in the absence of reinforcement.

Group 2: regularly rewarded

Group 1: no food reward

Group 3: no food until day 11

0

Average errors

2

4

6

8

10

Days 21 4 5 6 7 8 9 10 11 12 13 14 15 16 170 3

FIgUre 6.20 Tolman’s study of Latent Learning rats that were regularly reinforced for correctly running through a maze (Group 2) showed improved performance over time compared with rats that did not receive reinforcement (Group 1). rats that were not reinforced for the first 10 trials but were reinforced thereafter showed an immediate change in performance (Group 3). Note that between days 11 and 12 Group 3’s average number of errors decreased dramatically.

222 ■ ChapTer 6 lEarNING

6.4  How Do We Learn by Watching Others?

reinforcement led to demonstration of this learning over time through improved performance.

Another form of learning that takes place without reinforcement is insight learning. In this form of problem solving, a solution suddenly emerges after a delay—a period of either inaction or thinking through the problem. You prob- ably have had this sort of experience. After mulling over a problem for a while and seeming to get nowhere, suddenly you know the answer. The presence of reinforcement does not fully explain insight learning, but it helps determine whether the behavior will be repeated.

insight learning a sudden understanding of how to solve a problem after a period of either inaction or thinking about the problem.

■ Operant conditioning involves learning the association between a behavior and its consequences. This learning changes future behavior.

■ reinforcement increases the likelihood that a behavior will be repeated. By contrast, punishment reduces the likelihood that a behavior will be repeated.

■ Positive reinforcement and positive punishment change behavior by adding a stimulus. Negative reinforcement and negative punishment change behavior by removing a stimulus.

■ There are four schedules of reinforcement, and each schedule has a different effect on behavior.

■ Biological conditions—such as the release of dopamine or innate constraints— influence learning. Cognitive processes—such as cognitive maps, latent learning, and insight—also influence learning.

6.3 CheCKpoInT: How Do We Learn by Operant Conditioning ?

LearnIng goaLs readIng aCTIvITIes

a. remember the key terms related to learning by watching others.

list all of the boldface words and write down their definitions.

b. Understand the three types of learning by watching others.

Describe in your own words the three ways that we learn by watching others.

c. apply the three types of learning by watching others. Provide an example from your own life of each of the three types of learning by watching others.

d. Understand what happens in the brain during observational learning.

Summarize how mirror neurons may be the brain mechanism responsible for observational learning.

Suppose you were teaching someone to fly an airplane. How might you apply the learning principles discussed in this chapter to accomplish your goal? Obvi- ously, if you were training a beginning pilot, just waiting until your student did something right and then reinforcing that behavior would be disastrous. Simi- larly, though with less serious consequences, teaching someone to play football, eat with chopsticks, or perform complex dance steps requires more than simple

HOW DO WE lEarN BY WaTCHING OTHErS? ■ 223

reinforcement. We learn many behaviors not by doing them, but by watching others do them. This is true not only for mechanical skills, because we learn social etiquette by watching others. We sometimes learn to be anxious in particular situ- ations by seeing that other people are anxious. We often get our attitudes about politics and religion from parents, peers, teachers, and the media. In general, we learn by watching others in these three ways: observational learning, modeling, and vicarious conditioning.

Three Ways We Learn Through Watching  observational learning occurs when an individual either acquires or changes a behavior after viewing at least one performance of that behavior. This kind of learning is a powerful adaptive tool for both humans and other animals. Offspring can learn basic skills by watching adults perform those skills. They can learn which things are safe to eat by watching what adults eat, and they can learn to fear dangerous objects and situations by watching adults avoid them. Young children are sponges, absorbing everything that goes on around them (Figure 6.21). This behavior can be a bad thing too. When a young child starts to curse, you know the child learned that behavior from an adult, a sibling, or a peer.

BandUra’s researCh reveaLs LearnIng ThroUgh oBservaTIon The psychologist Albert Bandura conducted the most thorough work on obser- vational learning in the 1960s. In a now-classic series of studies, Bandura divided preschool children into two groups. One group watched a film of an adult playing quietly with a large inflatable doll called Bobo. The other group watched a film of the adult attacking Bobo furiously: whacking the doll with a mallet, punching it in the nose, and kicking it around the room. As shown in the Scientific Thinking box on p. 224, when the children were later allowed to play with a number of toys, including the Bobo doll, those who had seen the more aggressive display were more than twice as likely to act aggressively toward the doll (Bandura, Ross, & Ross, 1961).

Bandura’s results suggest not only that people learn through observation, but that exposing children to violence is associated with acting aggressively. But is that correct? This question comes up frequently in relation to the violent TV shows, movies, and video games that are common in our culture. If you had children, would you let them watch violent TV shows or play violent video games? The discussion in Being a Critical Consumer (p. 226) might help you answer that question.

LearnIng ThroUgh ModeLIng Can you remember learning to tie your shoes? It probably happened as you watched your parents using slow and exagger- ated motions, repeated many times. After your parents demonstrated how to tie shoes, you would have tried it yourself, making an effort to imitate them. Because humans can learn through observation, they readily imitate the actions of others and learn new things. The imitation of observed behavior is commonly called modeling.

Within a few days (or even hours) of birth, human newborns will model actions seen in others, such as sticking out the tongue and making facial expres- sions. And infants will continue to model gestures and other actions as they develop (Figure 6.22). Nonhuman animals may also be imitators. Indeed, one study found that infant macaque monkeys imitate facial expressions when they are 3 days old (Ferrari et al., 2006). However, research is unclear on whether nonhuman animals engage in imitation in the same way that humans do.

Modeling in humans is influenced by many factors. Generally, we are more likely to imitate the actions of models who are attractive, have high status, and

observational learning The acquisition or modification of a behavior after exposure to at least one performance of that behavior.

modeling The imitation of behavior through observational learning.

FIgUre 6.21 observational Learning This boy is not just watching his grandfather woodworking. Through observational learning, he is acquiring the skills to do woodworking himself.

FIgUre 6.22 early Modeling Babies frequently show learning by watching and then imitating behaviors and expressions.

224 ■ ChapTer 6 lEarNING

are somewhat similar to ourselves. In addition, modeling is effective only if the observer is physically capable of imitating the behavior. Simply watching Michael Phelps blast through the water in the 100-meter butterfly does not mean we could do that if we jumped in the pool. And the influence that models have on behavior often occurs implicitly—we are not aware that our behaviors are being altered. People might not even be aware that they have changed their ways of speaking or dressing to resemble those of celebrities. Overwhelming evidence says, however, that we imitate what we see in others. And we especially model the behaviors of people we admire.

Adolescent smoking is a particularly striking example of modeling behav- ior. For example, adolescents whose favorite actors smoke in movies are much more likely to smoke (Tickle, Sargent, Dalton, Beach, & Heatherton, 2001). In addition, the more smoking that adolescents observe in movies, the more positive their attitudes about smoking become, and the more likely they are to begin smoking (Sargent et al., 2005; Figure 6.23). Surprisingly, these effects are strongest among children whose parents do not smoke. Why would this be so? Movies tend to glamorize the habit, often presenting images of smokers as mature, cool, sexy—things adolescents want to be, and different from how they see their parents. Adolescents do not generally decide to smoke after watching one movie that makes smoking seem glamorous. But repeated demonstrations

FIgUre 6.23 Modeling and smoking Eye-catching movie images such as this one, from the 2012 James Bond movie Skyfall, contribute to viewers’ sense that smoking is a mature, cool, sexy behavior. Because people learn to model what they see, they readily imitate the actions of people they admire, including movie stars who smoke.

1

Hypothesis: Children can acquire behaviors through observation.

Research Method:

Result: When children were allowed to play with the doll later, those who had seen the aggressive display were more than twice as likely to act aggressively toward the doll.

Conclusion: Exposing children to violence may encourage them to act aggressively.

Question: Do you think that children hitting a blow-up doll were showing real aggressive behavior? How else might you interpret the children’s behavior?

Two groups of preschool children were shown a �lm of an adult playing with a large in�atable doll called Bobo.

2 One group saw the adult play quietly with the doll (activity not shown below).

3 The other group saw the adult attack the doll (activity shown in top row below).

sCIenTIFIC ThInKIng: Bandura’s Bobo Doll Studies Reveal Observational Learning

vicarious conditioning learning the consequences of an action by watching others being rewarded or punished for performing the action.

HOW DO WE lEarN BY WaTCHING OTHErS? ■ 225

shape their attitudes about smoking and subsequently lead to imitation. As adolescent viewers learn to associate smoking with people they admire, even fictional movie characters, they incorporate the general message that smoking is desirable.

LearnIng ThroUgh vICarIoUs CondITIonIng Another factor that determines whether a person imitates a model is whether he or she observes the model being rewarded for performing the behavior. In the study mentioned earlier, Bandura and colleagues showed children a film of an adult aggressively playing with a Bobo doll, but this time the film ended in one of three different ways (Bandura et al., 1963). In the first version, the control condition, the adult experienced no consequences for the aggressive behavior. In the second version, the adult was rewarded for the aggressive behavior with candy and praise. In the third version, the adult was punished for the behavior by being both spanked and verbally reprimanded.

When the children were subsequently allowed to play with the Bobo doll, those who observed the model being rewarded for aggressive behavior were much more likely to be aggressive toward the doll than were the children who watched the control condition of the film. In contrast, those who saw the model being punished were less likely to be aggressive than were those in the control group. Through vicarious conditioning, people learn about the consequences of an action by watching others being rewarded or punished for performing the action. This in turn affects people’s own likelihood to engage in that behavior at a later time (Figure 6.24).

These findings do not mean that the children who did not show aggression did not learn the behavior. Later, the children were offered small gifts to perform the model’s actions, and all—even those who had watched the model being punished—performed the aggressive actions reliably. As we noted earlier, a key distinction in learning is between the acquisition of a behavior and its performance. In this case, all the children acquired the behav- ior. In other words, they learned it. But only those who saw the model being rewarded performed the behavior. That is, not until the children themselves were actually rewarded for acting in that way did they all perform the behavior. Direct rewards prompted the children in the control group to reveal the behavior they had acquired.

Watching Others Results in   Cultural Transmission All humans belong to the same species and share the vast major- ity of genes. Around the world, however, there is enormous cultural diversity in what people think and how they behave. Would you be the same person if you had been raised in a small village in China, or in the jungles of South America, or in the mountains of Afghanistan? Probably not, since your religious beliefs, your values, even your musical tastes are shaped by the culture in your part of the world. Each piece of knowledge about a culture that can be shared, such as knowing it is a bad idea to text while driving, is a meme. Memes can be learned in many ways, such as conditioning through association or reinforcement. However, many memes are learned by watching the behavior of other people.

Evolutionary psychologists view memes as similar to genes. Like genes, memes are selectively passed on from one generation to the next. But unlike the

FIgUre 6.24 Learning Through vicarious Conditioning When a person observes someone else being rewarded or punished for a particular behavior, the observer may learn to do, or not do, the same thing. This type of learning happens all the time with siblings. Because this boy is watching his sister get a “talking to” after behaving badly, he will probably learn to not make the same mistake that she made.

226 ■ ChapTer 6 lEarNING

Carlos’s twin sons had finally gone to bed. They were particu- larly wound up tonight since they had just celebrated their 12th birthday and wouldn’t stop playing the new video game they had received. Carlos was looking forward to some peace and quiet so he could read Chapter 6.

as he read, Carlos became intrigued about the research on observational learning. I wonder if my sons are learning to be like the characters they see in the video games they play? This question had crossed his mind after the Newtown, Connecticut, school massacre in 2012. Many of the news reports suggested that violent video games could have been a cause of the shooter’s behavior. Carlos wondered: Do people learn to be violent by playing video games? Through- out the semester, Dr. Parretti had encouraged the students to be on the lookout for psychological research that could have real-life implications. Was there psychological research on this topic? What kind of study would convince me that children learn aggression from video games?

Carlos thought about correlational studies and what those would look like in this case. I guess a study could ask a group of kids how much they play video games and then measure how aggressive they are. Those sorts of stud- ies seemed pretty easy to conduct, but they left too many questions unanswered. If researchers found a correlation between frequency of video game playing and aggression, then maybe one did lead to the other, but in which direction? Maybe aggressive kids just like video games more, so they play them more often. Or maybe some other factor could be driving them both. Maybe it could have something to do with the children’s feelings of social isolation at school—kids who have fewer friends may be both more aggressive and more likely to entertain themselves with video games.

What would it take for Carlos to be completely convinced that children learn to be violent from video games? He would want to see an experimental study. In this study, research- ers would have one group of people play a violent video game while another group played a nonviolent video game. That arrangement would tell us whether children learn to be violent by playing any video game or violent games in particular.

The next day, with his professor’s help, Carlos found an interesting study done by Barlett and rodeheffer (2009).

This study looked at different types of video games and different outcomes. Study participants were randomly assigned to play either a realistic, violent video game (people shooting, as in “Conflict Desert Storm”) or a non violent video game (“Hard Hitter Tennis”). While partici- pants played the game, their physical arousal—for instance, their heart rate—was measured. Every 15 minutes, the researchers used a word completion task to measure the participants’ aggressive thoughts. They also used a ques- tionnaire, the State Hostility Scale, to measure participants’ aggressive feelings. after playing for 45 minutes, people who played realistic, violent video games had more aggres- sive feelings, more aggressive thoughts, and a higher heart rate than those who played nonviolent video games.

Carlos was impressed with how convincing the results were. Playing the violent video games clearly caused people to think aggressive thoughts and feel more aggressive, Carlos thought.

QUesTIon Although Carlos found the study convincing, do the find-

ings  show  that  violent  video  games  cause  school  shoot- ings? Do you think that people who choose to play these 

games in the real world differ from those who do not? What 

third  variables  might  explain  the  relationship  between 

video game use and school shootings?

BeIng a CrITICaL ConsUMer:

Does Watching Violent Media Cause Aggressive Behavior?

transmission of genes through natural selection, which typically occurs slowly over thousands of years, memes can spread quickly. For example, people’s adop- tion of the Internet is a meme that occurred worldwide. But some memes, such as fads, die out quickly.

Even nonhuman animals show this kind of passing along of knowledge. One good example of the cultural transmission of knowledge is the case of Imo, a macaque monkey. In the 1950s, researchers who were studying monkeys in Japan threw some sweet potatoes onto a sandy beach for the macaques there to eat. Imo

developed the habit of washing her sweet potatoes in the ocean to remove the sand. Within a short time, other monkeys copied Imo, and soon many monkeys were washing their potatoes before eating them. Through this type of learning, this meme has continued to be passed along from one generation to the next, and monkeys at this beach still wash their potatoes (Dugatkin, 2004; Figure 6.25).

Biology Influences Observational  Learning  Suppose you’re watching somebody handle a piece of paper and that person gets a paper cut. You might find yourself flinching as if you received the cut.

What happens in the brain during observational learning? When you watch someone performing an action, mirror neurons in your brain become activated (Iacoboni, 2009). Mirror neurons are especially likely to become activated when you observe someone making a movement that has some goal, such as reaching for a glass of water. Your mirror neurons are not activated when you see just the water glass or when you see a person just sitting. But these same mirror neurons become activated when you reach for a glass of water. Every time you watch another person engaging in an action, similar neural circuits are firing in your brain and in the other person’s brain.

Scientists are debating the function of mirror neurons. This system may support observational learning. However, the firing of mirror neurons in the observer’s brain does not always lead that person to actually imitate the behav- ior being observed. Therefore, some theorists think that mirror neurons may help us explain and predict others’ behavior. In other words, mirror neurons may allow us to step into the shoes of people we observe so we can better under- stand those people’s actions. One theory is that mirror neurons are the neural basis for empathy. Empathy is the emotional response of feeling what other people are experiencing, such as our flinching when someone else receives a paper cut.

HOW DO WE lEarN BY WaTCHING OTHErS? ■ 227

FIgUre 6.25 Memes In the 1950s, a Japanese macaque named Imo developed the meme of washing sweet potatoes in the ocean. Imo’s fellow monkeys observed this behavior and copied it. as shown here, the descendants of these macaques continue the behavior of washing sweet potatoes in the ocean.

■ Humans learn basic and complex skills, beliefs, attitudes, habits, and emotional responses by watching others. Three types of learning by watching are observational learning, modeling, and vicarious learning.

■ Watching others also allows transmission of cultural information.

■ Mirror neurons become active when we observe a goal-directed behavior. This response may be a neural basis of observational learning.

6.4 CheCKpoInT: How Do We Learn by Watching Others?

228 ■ ChapTer 6 lEarNING

BIG QUESTION LEARNING GOALS

a. remember the key terms about learning.

b. Understand the three main types of learning.

c. apply learning to your life.

d. Understand how the brain changes during learning.

a. remember the key terms about operant conditioning.

b. Understand the four types of reinforcement and punishment in operant conditioning.

c. apply the four schedules of reinforcement.

d. apply the three cognitive aspects of conditioning.

B IG

P IC

T U

R E

`

a. remember the key terms about classical conditioning.

b. apply the four steps of classical conditioning.

c. apply the concepts of acquisition, extinction, spontaneous recovery, generalization, and discrimination.

d. analyze the acquisition of a phobia and counterconditioning to reduce a phobia.

a. remember the key terms related to learning by watching others.

b. Understand the three types of learning by watching others.

c. apply the three types of learning by watching others.

d. Understand what happens in the brain during observational learning.

6.1 What Are the Three 

Ways We Learn?

6.2 How Do We 

Learn by Classical 

Conditioning?

6.3 How Do We Learn  

by Operant 

Conditioning?

6.4 How Do We Learn by 

Watching Others?

BIG PICTUrE ■ 229

KEY TERMS CHECKPOINT

■ learning is a change in behavior, resulting from experience. There are three main types of learning.

■ Non-associative learning about a stimulus happens through habituation and sensitization.

■ associative learning about relationships between events occurs

learning habituation sensitization

■ Operant conditioning involves learning the association between a behavior and its consequences. This learning changes future behavior.

■ reinforcement increases the likelihood that a behavior will be repeated. By contrast, punishment reduces the likelihood that a behavior will be repeated.

■ Positive reinforcement and positive punishment change behavior by adding a stimulus. Negative reinforcement and negative

punishment change behavior by removing a stimulus.

■ There are four schedules of reinforcement, and each schedule has a different effect on behavior.

■ Biological conditions—such as the release of dopamine or innate constraints—influence learning. Cognitive processes—such as cognitive maps, latent learning, and insight—also influence learning.

operant conditioning positive reinforcement negative reinforcement positive punishment negative punishment fixed interval schedule (FI) variable interval schedule (VI) fixed ratio schedule (Fr) variable ratio schedule (Vr) partial-reinforcement

extinction effect cognitive map latent learning insight learning

a fear experience. Techniques based on classical conditioning, such as counterconditioning, can be used to treat phobias.

■ Classical conditioning helps animals learn responses that aid survival. The cognitive model states that the amount of conditioning that occurs is determined by how unexpected or surprising the unconditioned stimulus is.

through classical conditioning and operant conditioning.

■ learning also occurs when we watch what others do.

■ learning occurs when synaptic connections in the brain become stronger over time through long-term potentiation (lTP).

■ In Pavlov’s classical conditioning, a conditioned stimulus that is predictably associated with an unconditioned stimulus produces a learned, conditioned response.

■ Six factors affect the strength and persistence of learning from classical conditioning.

■ Phobias may develop when classical conditioning leads to generalization of

classical conditioning unconditioned stimulus (US) unconditioned response (Ur) conditioned stimulus (CS) conditioned response (Cr) acquisition extinction spontaneous recovery stimulus generalization stimulus discrimination

■ Humans learn basic and complex skills, beliefs, attitudes, habits, and emotional responses by watching others. Three types of learning by watching are observational learning, modeling, and vicarious learning.

■ Watching others also allows transmission of cultural information.

■ Mirror neurons become active when we observe a goal-directed behavior. This response may be a neural basis of observational learning.

observational learning modeling vicarious conditioning

For a self-quiz on this chapter, go to the back of the book and find Appendix B:  Quizzes.

230    ■    Chapter 7  MeMory

7

BIG QUeSTIoNS 7.1 How Do We Acquire Memories?

7.2  How Do We Maintain Memories Over Time?

7.3   What Are Our Different Long-Term Storage Systems?

7.4 How Do We Access Our Memories?

Memory SCOtt haGWOOD IS aN OrDINarY MaN. He was a mediocre student in high school and

college, then became a businessman and consultant. He is somewhat reserved and is uncomfort-

able being in the spotlight. But he is in the spotlight a lot: He is a four-time winner of the USA

Memory Championship and one of only 122 Grand Masters of memory. Scott Hagwood’s memory

abilities may be among the best developed in the world. To become a Grand Master of memory, he

had to compete at official competitions. He also had to show that he could memorize 1,000 digits

in less than an hour, the order of 10 shuffled decks of playing cards in under an hour, and the order

of one shuffled deck of cards in less than two minutes (Figure 7.1).

    ■    231231

232    ■    Chapter 7  MeMory

What makes Hagwood amazing is that he was not born with extraordinary

memory skills. As an adult, he learned that he had thyroid cancer. A common

complication of the disease is deficits in memory. Hagwood became concerned

because “I didn’t have a great memory to begin with. I thought there might be

something I could do to help facilitate my memory.” So he set out to improve

his memory before it was impaired by his medical condition.

Hagwood taught himself how to use memory tools to be successful at the

USA Memory Championship. These memory tools are based on the idea that

the more meaningful something is, the easier it is to remember. For example,

to memorize playing cards, competitors mentally link each playing card with

a person, an action, or an object. every group of three or more cards makes

a sentence. edward Cooke, a 23-year-old competitor and Grand Master from

england, explains that when he sees a three of clubs, a nine of hearts, and a

nine of spades, this group of three cards triggers a visual image of “Brazilian

lingerie model Adriana Lima in a Biggles biplane shooting at his old public-

school headmaster in a suit of armor.” While the technique may sound silly, it

creates a meaningful and vivid image that is easy to remember.

But this example covers only three cards. Contestants must memorize the

order of 10 decks of cards—that’s 520 cards—in less than an hour. To keep all

the images in order, contestants take a “mental walk” through a familiar loca-

tion. There, the visual images are “placed” in predetermined locations along the

walk. Cooke’s mental walk begins at his favorite pub in oxford, england. It ends

at a nearby hotel. When he must recall the cards, he takes this mental walk and

sees all the images in the places where he put them. Then he can recall them in

the correct order.

Feats such as these seem superhuman. But Scott Hagwood’s case provides

a simple message: We all can improve our memory just by learning and using

simple techniques. Thinking back to his school days, Scott now realizes that he

was able to understand the material. He simply didn’t know how to study prop-

erly. Now Scott tours the country, teaching “regular people” how to improve

their memory. In this chapter, you will learn the same tips that Scott teaches, as

we discuss what memory is and how it works.

7.1 How Do We Acquire Memories?

Figure 7.1 Memory Competition At the USA Memory Championship, a

member of the competitive memory team

from the University of Pennsylvania is

using a strategy to make information more

meaningful and easy to remember. In this

chapter, you will learn such tools, and they

can help you improve your memory skills.

LearNING GOaLS    reaDING aCtIvItIeS

a. remember the key terms about memory and encoding. List all of the boldface words and write down their

definitions.

b. Analyze the three phases of information processing in

acquisition of a memory.

Identify how you encoded, stored, and can retrieve a

specific memory that you have.

c. Understand how attention affects memory. Summarize in your own words how the presence or

absence of attention influences the encoding of a memory.

d. Apply filter theory to your ability to selectively attend to

important information.

Use filter theory to explain how you can attend to

relevant information during a lecture and ignore irrelevant

information.

HoW Do We ACQUIre MeMorIeS?    ■    233

Memory is the nervous system’s capacity to acquire and retain information and skills. This capacity allows us to take information from experiences and store it for retrieval later. The skills shown by the contestants at the USA Memory Champion- ship make it seem that we remember information in the same way a video camera captures and faithfully retrieves events. But that’s not the case at all. Unlike in video recording, not all experiences are equally likely to be remembered. Some life events leave no lasting memory. Other life events are remembered but later forgotten. Still others remain for a lifetime. We have multiple memory systems, and each memory system has its own “rules.” For example, the processes that underlie memory for information we will need to retrieve in 10 seconds are different from the processes that underlie memory for information we will need to retrieve in 10 years.

In addition, unlike video recordings, our memories are often incomplete, biased, and distorted. Two people’s memories of the same event can differ greatly, because each person stores and retrieves memories of the event differently. We tend to remember personally relevant information and filter our memories through our own perceptions and knowledge of related events. In other words, memories are not “truth,” but our perception of what occurred. And this percep- tion is altered during the processes of acquiring, maintaining, and re-accessing the memories.

We Acquire Memories by Processing Information To understand the three processing phases of memory, consider that right now you are reading the information in this textbook. Presumably, you are trying to remem- ber the information. In the encoding phase, your brain changes information—for example, what you see on the page when you are reading this text—into a mean- ingful neural code that it can use (Figure  7.2, Step 1). The storage phase is how you maintain the coded representation in a network of neurons in the brain. Stor- age can last a fraction of a second or as long as a lifetime. Think of this phase as maintaining the text material from when you read it until you take the test, or even longer (see Figure 7.2, Step 2). As we will see later in the chapter, there are

Figure 7.2 three phases of Information   processing in Memory

Encoding: changing information into a neural code the brain can use. Here the reader is encoding the visual input—the words and pictures on the page.

1 Storage: maintaining information for some time. Here the reader is storing the information he has encoded. He is strengthening his mental storage by taking notes.

2 Retrieval: re-accessing the information for use. If the reader encodes and stores well, he will later be able to retrieve the information and use it, such as on an exam.

3

memory The nervous system’s capacity to acquire

and retain skills and knowledge for later

retrieval.

encoding The processing of information so that it

can be stored.

storage The retention of encoded representations

over time.

234    ■    Chapter 7  MeMory

at least three storage systems, which differ in how long they store information. In retrieval, the third phase of memory, you re-access the information. Think of this phase as bringing to your mind a previously encoded and stored memory when it is needed, such as when you need to answer a question on your psychology exam (see Figure 7.2, Step 3). Unfortunately, we all know that sometimes we experience memory failure. If memory were like a video recorder, we would never get an exam question wrong. But we do get things wrong, and this is in part due to how we pay attention to the information.

Attention Allows Us to Encode a Memory Many students say they have memory problems. Specifically, they have trouble remembering the material covered in class and in their textbooks. But their problems often have nothing to do with the way their brains work. Rather, they do not pay attention when they are supposed to be learning.

Starting when you were very young, you’ve probably heard your parents and teachers telling you to “pay attention.” To get information into memory, we need to pay attention to it. That is, we need to be alert and focus on the information. Think about the difference between the words look and see, and between listen and hear. Look and listen refer to directing certain mental processes, called attention, to some information. We do so at the cost of paying less attention to other information, however. In fact, the word pay implies that costs are associ- ated with attending to some information but not to others. That is, attention is limited. When it is divided among too many tasks or the tasks are difficult, our performance on each task suffers. In short, if we do not pay attention to look or listen, then we cannot even process sensory input to see or hear. In this case, we will not have a memory of that information.

Having limited attention helps us to function in the world. Imagine what your life would be like if you could not block out the irrelevant information that comes at you all the time. A task as simple as listening to your instructor during class requires focused attention. If a classmate recently colored her hair purple, that might capture your attention and make it difficult to follow what the instructor is saying. Or if the lecture is somewhat boring, you might start daydreaming. In short, your attention can be distracted by external cues or by internal thoughts and memories (Chun, Golomb, & Turk-Browne, 2011). Let’s consider the basic prin- ciples of how human attention works.

vISUaL  atteNtION Imagine that you are trying to find a person in a large crowd of people. How can you do this? According to one theory, we automatically pay attention to and recognize basic visual features in an environment, including color, shape, size, orientation, and movement. This behavior enables us to selec- tively attend to a visual object with one important feature by blocking further processing of other, dissimilar features (Treisman & Gelade, 1980).

For example, if the person you are looking for is the only one wearing a red coat, then she will just “pop out” (Figure 7.3a). You need very little attention to find her in the crowd, and finding her will take less time. By contrast, searching for a visual object with two features is slower and more difficult and requires more attention. If you are searching for a woman wearing a red coat when some men in the crowd are wearing red coats, finding the woman will be harder and take longer (Figure 7.3b). This task— searching for an object with two features—reveals how attention is a limited process. It is hard to perform two attentionally demanding tasks at the same time. You can feel the effort required in a similar task if you do the Try It Yourself activity.

retrieval The act of recalling or remembering stored

information when it is needed.

attention Focusing mental resources on information;

allows further processing for perception,

memory, and response.

Figure 7.3 visual attention to the Feature   of Color (a) It requires less attention to process a single feature of an object, such as when

you need to find a person in a red coat.

(b) It requires greater attention to process two features, such as a woman in a red

coat. This example shows that attention

is limited and that we need to direct

attentional resources to what is important.

HoW Do We ACQUIre MeMorIeS?    ■    235

trY It YOUrSeLF:  Visual Attention

1. As quickly as you can, count

the number of black objects.

2. As quickly as you can, count

the number of green squares.

you probably noticed that the

first task was very easy and

took no time at all. you breezed through this one because

you were paying attention to only one feature: black. By

comparison, the second task was probably more difficult

and took longer. Why? you had to pay attention to two

features of one object. you were looking for objects that

are both green and square. The second task was harder even though in both cases the number of items that you

counted was the same: 5.

Figure 7.4 auditory attention to “Shadow”   Message in One ear In this task, the participant receives a

different auditory message in each ear

and must repeat, or “shadow,” just one of

the messages. Typically, the person has no

memory of the other message. This result

shows that attention is limited and that we

remember only what we pay attention to.

Ignored input: The horse galloped across the �eld…

Attended input: President Lincoln often read by the light of the �re…

Speech output: President Lincoln often read by the light of the �re…

aUDItOrY  atteNtION Auditory attention is also lim- ited. Imagine that you are at a party, talking with a friend. Suddenly you hear someone behind you mention your name, or a particularly juicy piece of gossip captures your attention. Your attention now focuses on that conversation, so you will lose the thread of your original conversation. This example again shows that it is hard to perform two attention-demanding tasks at the same time.

Selective-listening studies examine what we do with auditory information that is not attended to. In studies by Cherry (1953), participants wore headphones that delivered one message to one ear and a different message to the other ear. Each person was asked to attend to one message and “shadow” it by repeating the message aloud (Figure  7.4). Later on, the participants often had no knowledge about the content of the unattended message. However, when a partic- ipant’s own name was presented as part of the unattended message, participants reported hearing their name, though they knew nothing about the rest of the message. This finding shows that some important information is attended to. To be important, information has to be personally relevant, such as your name or the name of someone close to you, or it has to be particularly loud or different in some obvious physical way.

Selective Attention Allows Us to Filter Unwanted Information According to this research, attention selectively allows us to focus on what is important in a situation. It generally also allows us to ignore what is irrelevant. Let’s apply this principle to your experience in class: If you focus attention on listening to the instructor, you are likely to encode the information so it can be stored in memory. By contrast, if you pay attention to your classmate’s purple hair or your Facebook page, you may never encode the lecture information. Later on, you probably won’t consciously remember the material from class. This example shows how some stimuli demand all of our attention and nearly prevent the ability to attend to anything else.

FILter theOrY  In 1958, the psychologist Donald Broad- bent developed filter theory to explain how we selectively attend to the most important information. In this model, attention is like a filter. Important information is allowed through the filter, but irrelevant information is prevented from getting through the filter. However, what is important enough to get through the filter? And what happens to infor- mation that is filtered out, or ignored? Is it not processed at all?

Some stimuli, such as those that evoke emotions, can readily capture our atten- tion because they provide important information about potential threats in our environment (Phelps, Ling, & Carrasco, 2006). Faces are a good example of stim- uli that are allowed through the attentional filter because they provide important social information. For example, a face indicates whether someone is a potential mate (i.e., has an attractive face) or may intend to cause physical harm (i.e., has an angry face). Indeed, a series of studies found that the attentional system prioritizes

236    ■    Chapter 7  MeMory

change blindness An individual’s failure to notice large

visual changes in the environment.

faces, especially when they appear threatening, over less meaningful stimuli (West, Anderson, & Pratt, 2009).

Studies such as these indicate that decisions about what to attend to are made early in the perceptual process. In certain situations, however, unattended informa- tion can “leak” through the filter to be processed at least to some extent. We saw such a situation with the selective listening participants who heard their name mentioned in the unattended message. On the other hand, because we cannot attend to every- thing in the vast array of visual information available, often we are “blind” to even large changes in our environment. This phenomenon is known as change blindness.

ChaNGe  BLINDNeSS If the person you were talking to suddenly changed into another person, would you notice? The answer seems obvious: Of course you would. However, when this question was explored experimentally, the results were surprising (Simons & Levin, 1998). In this research, shown in the Scientific Think- ing feature, participants were approached by a stranger who asked for directions. Then the stranger was momentarily blocked from the participants’ view by a large object and replaced with another person of the same sex and race. Surprisingly, half of the people giving directions never noticed that they were talking to a differ- ent person.

When giving directions to a stranger, we normally do not attend to the distinctive features of the stranger’s face or clothing. If we are unable to recall those features later, it is not because we forgot them. More likely, it is because we processed those features very little in the first place. Because we didn’t process the features, they were never encoded into memory. After all, how often do we need to recall such information?

SCIeNtIFIC thINKING: Change Blindness

21

Hypothesis: People can be “blind” to large visual changes around them.

Research Method:

Results: Half the participants giving directions never noticed they were talking to a different person (as long as the replacement was of the same race and sex as the original stranger).

A participant (right) is approached by a stranger asking for directions.

The stranger is momentarily blocked by a larger object.

3 While being blocked, the original stranger is replaced by another person.

Conclusion: Change blindness results from inattention to certain visual information.

Question: Do you think we would be more likely to notice some people being switched than others? If so, what aspects of people would we be most likely and least likely to notice being switched?

HoW Do We ACQUIre MeMorIeS?    ■    237

As change blindness illustrates, we can attend to only a limited amount of information. Large discrepancies exist between what most of us believe we can pay attention to and what we do actually attend to. As a result, our perceptions of the world are often inaccurate. However, we have little awareness of our percep- tual failures. We simply do not know how much information we miss in the world around us. Every time we miss a piece of information, we don’t encode the infor- mation for storage in memory. In other words, every time we fail to pay attention, we most likely will not create a memory of the information.

LaptOpS IN the CLaSSrOOM  It can be hard to pay complete attention for an entire class period even with the most exciting teachers. For this reason, many of your teachers try to include active participation during class. The rise of laptop computers and smartphones in the classroom over the last decade has increased the difficulty for teachers to hold students’ attention (Figure  7.5). Ideally, such technology allows students to take notes, access online materials, or participate in classroom exercises. Unfortunately, students can also tune out during class by checking Facebook or email, texting, or watching YouTube videos.

After reading the earlier sections of this chapter, you might not be surprised that paying attention to your computer or smartphone might lead you to miss important details going on around you, such as important information in the class. Overwhelming evidence shows that students who use Facebook, text, surf the Internet, and so on during class do more poorly in college courses (Gingerich & Lineweaver, 2014; Junco & Cotten, 2012). Poor performance can happen even if students do not multitask. According to one study, taking notes in class on a laptop rather than by hand leads to worse performance on tests of that material (Mueller & Oppenheimer, 2014). Even those who are simply sitting near someone playing around on the Internet during class score lower grades (Sana, Weston, & Cepeda, 2013). If you use your laptop or smartphone to look at irrelevant materials, you are harming your learning and the learning of others.

Students often do not think they are missing anything when they multitask. The irony is that it takes attention to know what you are missing. If your attention is elsewhere and you miss something important mentioned by your teacher, not only did you miss what the teacher said, but you will not even know that you missed anything! To do best in your courses, give your complete and undivided attention to your teachers. That strategy will increase how much you remember from your classes.

■ Memories are created by encoding information from sensory input. encoded

information is maintained in storage. retrieval allows accessing of previously

encoded and stored information.

■ Visual attention can be focused on encoding one feature of an object more

quickly and effortlessly than two or more features.

■ It is difficult to focus auditory attention on encoding more than one message

at a time, and most unattended auditory information is not processed.

■ Selective attention filters out irrelevant information and causes people not to notice large changes in the environment.

7.1  CheCKpOINt:  How Do We Acquire Memories?

Figure 7.5 technology in the Classroom Today’s students use electronic devices in

the classroom productively (as in taking

notes) and nonproductively (as in texting).

However, both of these uses are associated

with lower grades.

238    ■    Chapter 7  MeMory

Have you been paying attention to what you are reading in this chapter? If you have, then you should be able to answer this question: What is the first phase of process- ing involved in creating a memory? Did you remember that the first step is when information is processed for memory by encoding it in the brain (see Figure 7.2)? Now we will explore the second key phase, in which memories are stored so that the information can be used at a later time.

So how is information maintained over time through storage? In 1968, the psychologists Richard Atkinson and Richard Shiffrin proposed that we have three different types of memory stores: sensory storage, short-term storage, and long- term storage (Figure 7.6). Each of these memory stores retains different encoded input, and each has the capacity to maintain a certain amount of information for a certain length of time. For a summary of these memory stores, see table 7.1. Now let’s look at the three memory stores in more detail.

Sensory Storage Allows Us to Maintain Information Very Briefly “You’re not paying attention to me.” Most of us have likely heard this complaint at some point. In that situation, even if you were thinking about something else, you

Figure 7.6 three-part Memory Storage  System This model proposes three

different memory stores:

(1) sensory storage, (2) short-

term storage, and (3) long-term

storage. each memory store

retains different encoded input,

and each store has its own

duration and capacity.

Encoding Attention and

encoding

Attention and

encoding

Retrieval

Sensory input from external world

Sensory input

Unattended information is lost.

Information that is not manipulated is lost.

Some information may be forgotten.

Information is manipulated in working memory (repeating, chunking).

Sensory storage Short-term storage

Long-term storage

7.2 How Do We Maintain Memories Over Time?

LearNING GOaLS    reaDING aCtIvItIeS

a. remember the key terms about storage of memories. List all of the boldface words and write down their definitions.

b. Understand sensory storage. explain in your own words how visual sensory storage and

auditory sensory storage provide perceptual continuity.

c. Understand the relationship between short-term storage

and working memory.

Summarize how using working memory to chunk

information increases the capacity and duration of

short-term storage.

d. Apply encoding processes in long-term storage to your

life.

Provide a description of how you have used maintenance

rehearsal and elaborative rehearsal to encode and maintain

two memories in long-term storage.

e. Understand how information is organized in long-term

storage based on semantic meaning.

Describe how association networks explain why hearing

“fire engine” is more likely to make a person remember

“ambulance” than “red.”

HoW Do We MAINTAIN MeMorIeS oVer TIMe?    ■    239

may have been relieved to find that you could repeat the last few words the other person spoke. Sensory storage is the reason you can do this.

FIve tYpeS OF SeNSOrY StOreS Recall from Chapter 5 that we obtain all our information about the world through our senses: vision, hearing, taste, smell, and touch. This sensory information is the basis for all of our memories. When you see someone twirling a sparkler, for instance, the visual input to your eyes is trans- duced into a neural signal that is processed in your brain. One way this sensory input is processed is through encoding into sensory storage. Here, the sensory input—the sparkler—leaves a visual trace in the nervous system for just a fraction of a second. In this way, sensory storage is a very brief maintenance system for sensory information. In this case, the system lets you see the trail of light left by the sparkler just long enough to see the message written in the sparkler’s light (Figure 7.7).

In the same way that one type of sensory storage very briefly maintains visual input, four other types of sensory stores main- tain all the other sensory input: auditory, smell, taste, and touch. These kinds of input are not what we usually think of as memory, because each sensory store is so brief that we are unaware it is operating. However, sensory storage of all this vast amount of input is important because it allows us to have a coherent experience of the world around us.

DUratION aND CapaCItY OF SeNSOrY StOraGe How long can infor- mation be maintained in sensory storage? And how much information can be maintained? In a classic 1960 study, the cognitive psychologist George Sperling provided the initial answers to these questions for visual sensory storage.

Three rows of four letters were flashed on a screen for one-twentieth of a second (Figure 7.8a). Then participants were asked to recall all 12 of the letters (i.e., provide a whole report). Most people could name only three or four letters (Figure 7.8b, blue line). But they stated that they believed they had seen all the

sensory storage A memory storage system that very briefly

holds a vast amount of information from

the five senses in close to their original

sensory formats.

Figure 7.7 Sensory Storage If you stood in front of this sparkler, you

could see the word LOVE spelled by the sparkler because the visual input would be

maintained briefly in sensory storage.

Figure 7.8 Duration and Capacity of Sensory  Storage A clever experiment investigated visual

sensory storage. (a) Twelve letters were flashed. In the whole report condition,

participants had to name all 12 letters. In

the partial report condition, they heard a

tone that signaled which row of 4 letters

to report. (b) According to the results of the partial report condition, many of

the 12 letters are maintained in sensory

storage for about one-third of a second.

(b)

(a)

Rows of letters

Tone signaling which row to report

GTFB

QZCR

KPSN

High tone

Medium tone

Low tone

Percentage of letters remembered

Delay of signal (seconds)

.150 .3 1.0 0

25

100

75

50

Whole report

Partial report

SeNSOrY   StOraGe

ShOrt-terM   StOraGe

LONG-terM   StOraGe

Function   of storage 

• Creates perceptual continuity for the world around us

• Maintains information for immediate use

• Stores information for re-access and use at a later time

encoding   for storage       

• In the sense it is experienced: visual, auditory, taste, smell, and touch

• Primarily auditory

• Also visual and semantic

• Primarily semantic

• Also visual and auditory

• Dual coding provides richest encoding

Duration   of storage      

• Up to a few seconds, depending on the sense

• About 20 seconds

• Indefinite with working memory manipulation of items

• Probably unlimited

Capacity   of storage     

• Vast due to huge amount of sensory input

• About 7 items, plus or minus 2

• Using working memory aids capacity

• Probably unlimited

TABLe 7.1

the three Memory Stores

letters. Perhaps participants actually had a very brief memory for all 12 of the items. But in the time it took them to name the first 3 or 4 letters, they forgot the other 8 or 9 letters.

To test this interpretation, Sperling repeated the study, but he asked partici- pants to report just one of the three rows of letters (i.e., partial report). They knew which row they had to report based only on hearing a high-, medium-, or low- pitched sound (see Figure 7.8a). When the sound occurred immediately after the letters disappeared, the participants correctly remembered almost all the letters in the signaled row. But when there was a longer delay between the disappearance of the letters and the sound, participants recalled fewer letters in the signaled row. Based on this result, Sperling concluded that participants maintained many of the 12 items in sensory storage for about one-third of a second (see Figure 7.8b, green line). After that very brief period, the trace of the memory in sensory storage faded progressively until it was no longer accessible.

By maintaining a large amount of information for a fraction of a second, sensory storage enables us to experience the world as a continuous stream of information rather than as discrete sensations (see Table 7.1). You can see this for yourself in the Has It Happened to You? feature. Also thanks to visual sensory storage, you can enjoy a movie. A movie is actually a series of still pictures that follow each other very closely in time. But your sensory storage retains information just long enough for you to connect one image with the next in a smooth way so that the images look like continuous action. Indeed, sensory memory is what explains the phenomenon of stroboscopic motion discussed in Chapter 5. Although sensory storage provides continuity, we can’t remember all the vast amount of information that comes in through our senses because we do not pay attention to most of it. It is only when we focus our attention that information is processed into short-term storage.

Working Memory Allows Us to Actively Maintain Information in Short-Term Storage What do you do when you need to remember a phone number, such as 463-5456, for a few seconds? If you are like most people, you probably repeat the numbers silently in your head until you can write them down or call them. Some people may remember the number temporarily by visualizing the numbers. Your ability to maintain the numbers by repeating or visualizing them for a time shows the important role of short-term storage in maintaining information.

Researchers initially saw short-term  storage as simply a buffer, or holding place. A small amount of information could be encoded, primarily based on audi- tory information but also based on visual information, and maintained for only a short time. According to this view, we could remember a phone number for a few seconds, but there was no mechanism to actively manipulate information in short- term storage. Newer research has revealed that short-term storage includes the important process of working  memory. As the name implies, working memory enables us to work on the information we have in short-term storage (Baddeley, 2002; Baddeley & Hitch, 1974). So working memory allows us to actively process sounds, images, and ideas. This mechanism lets us repeat a phone number so that we can maintain it longer in short-term storage.

To understand the relationship between short-term storage and working memory, let’s examine the duration and capacity of short-term storage (see Table 7.1). We’ll see how working memory can increase these qualities.

short-term storage A memory storage system that briefly holds

a limited amount of information in awareness.

working memory An active processing system that allows

manipulation of different types of

information to keep it available for

current use.

haS It happeNeD  

tO YOU? 

Eyeblinks Reveal Sensory Storage

Blink a few times. Did you notice

that you still “see” the world even

when you blink, although your

eyes are closed? you continue to

see even when you blink because

visual sensory storage “fills in” the

visual information so you keep

seeing it for about a quarter of a

second, even when your eyes are

closed.

Now blink more slowly, so

your eyes stay closed a bit longer.

you will start to see just a “blank

screen,” which is the back of your

eyelids. This happens because

your blinks are now taking

longer than the duration of visual

sensory storage. your memory

can’t keep that amount of visual

information in mind for very long,

so now you see just darkness.

240    ■    Chapter 7  MeMory

DUratION  OF  ShOrt-terM  StOraGe To investigate how long information is maintained in short-term storage, researchers gave participants a string of three meaningless letters to remember, such as X C J (Peterson & Peterson, 1959). Then participants had to count backward by threes from 100 for a period of time before being asked to recall the letters. As shown in Figure 7.9, if the participants did no backward counting, then they recalled about eight letter strings. However, after only six seconds of backward counting, participants recalled fewer than four letter strings. By 18 seconds of counting, most people could not recall any of the letter strings. So, in the best case, people can remember about eight items in short-term storage. In addi- tion, short-term storage lasts up to 20 seconds when people don’t use working memory processes to actively maintain the information they want to remember.

By contrast, if people are allowed to use working memory to manipulate the letters by repeating them over and over, then the information can be maintained for at least as long as the person continues to pay attention to repeating the letters. This research indicates that although short-term storage may be a “location” for maintaining memories, working memory allows manipulation of sounds, images, and ideas for longer maintenance in short-term storage (Baddeley, 2002; Baddeley & Hitch, 1974).

CapaCItY OF ShOrt-terM StOraGe Completing the backward-counting task in the example just described makes it impossible to repeat the letters using working memory. This effect shows that without working memory, we can hold only a limited amount of information in short-term storage at a time. The cogni- tive psychologist George Miller noted that the capacity limit of short-term storage is generally seven items (plus or minus two), which is referred to as the memory span (Miller, 1956). Notice that this memory span is consistent with the research findings in Figure 7.9, where participants remembered eight letter strings. Even so, Miller’s estimate may be too high, as some research suggests that short-term storage may be limited to as few as four items (Conway et al., 2005). Some individuals have a smaller or larger memory span. Capacity of short-term storage increases as children develop (Garon, Bryson, & Smith, 2008) and decreases with advanced aging (McCabe et al., 2010). Do the activity in Try It Yourself to check your own memory span.

Because short-term storage is limited in capacity, you might expect people to have great difficulty remembering a string of letters such as NHTSACAFBIMSCIAILDEA. These 20 letters would tax even the largest memory span. But what if we organized the information into smaller, meaningful units? For instance, NH TSA CA FBI MS CIA IL DEA. Here the letters are shown grouped together to produce abbrevia- tions for states and acronyms for U.S. federal government agencies. This process of using working memory to organize information into meaningful groups or units is known as chunking. The more efficiently you chunk information, the more you can remember.

Chunking makes information much easier to recall for two reasons. First, by using working memory, we can reduce

Number of letter strings correctly recalled

Time spent counting backward (seconds)

930 6 12 15 18 0

2

4

6

8

10

Figure 7.9 Duration and Capacity of Short-term  Storage In an experiment that explored short-term

storage, it was found that about 8 items

can be maintained for about 20 seconds

when a person is prevented from using

working memory processes.

chunking Using working memory to organize

information into meaningful units to

make it easier to remember.

trY It YOUrSeLF:  Digit Span Task

1. Have a friend read the first row of numbers to you at

the rate of one per second.

2. When the person is done reading, write down the

numbers in the order you heard them.

3. repeat the process with each row until you reach a

row where you fail to recall the numbers in the correct

order.

4. Whichever row your memory failed on, go to the row

above it and count the number of digits that you

were correctly able to recall in that row. This number

is your short-term storage digit span. For example,

if you made a mistake on the row 19223530, but

recalled all the numbers in row 0401473, then your

memory span is 7 items.

  925   8642   37654   627418   0401473   19223530   486854332   2531971768   85129619450   918546942937

HoW Do We MAINTAIN MeMorIeS oVer TIMe?    ■    241

242    ■    Chapter 7  MeMory

the 20 items to be recalled into 7 chunks, and 7 items are within the capacity of our memory span. Second, as you saw when we described the use of memory tools in the USA Memory Championship, meaningful units are easier to remember than nonsense units. Meaningful units are easier to remember because they draw on information that we already know. In short, chunking shows how working memory can increase the capacity of short-term storage, just as repetition can extend the duration of short-term storage.

Master chess players use this memory tool when they glance at a scenario on a chessboard, even for a few seconds, and later reproduce the exact arrangement of pieces (Chase & Simon, 1973). They instantly chunk the board into a number of meaningful units based on their prior experience with the game. If the pieces are arranged on the board in ways that make no sense in terms of chess, however, experts are no better than novices at reproducing the board. In general, the greater your expertise with the material, the more efficiently you can chunk information. As a result, you will be able to transfer more information into long-term storage, and you will be able to access and use that information later when you need it.

Long-Term Storage Allows Us to Maintain Memories Relatively Permanently Do you remember the phone number that was given at the beginning of the section on short-term storage? Unless you really paid attention and repeated the number, it’s unlikely that you remember it. You might have maintained the information in short-term storage for a few seconds, but it was probably not processed into long- term storage.

When people talk about memory, they usually are referring to this relatively permanent type of memory. To envision long-term storage, try to imagine every- thing you know and everything you are likely to know in your lifetime. It is hard to imagine how much information that might be, because you can always learn more. Unlike the other two memory stores, long-term storage has nearly limitless capac- ity and duration (see Table 7.1). This type of storage enables you to remember nurs- ery rhymes from childhood, the meanings and spellings of words you rarely use (such as aardvark), what you had for lunch yesterday, and so on. Given the billions of sensory experiences and thoughts we have each day, some type of filtering system must limit what goes into long-term storage. So what gets prioritized for encoding into long-term storage?

Generally, information that helps us adapt to our environment is likely to be transformed into a memory held in long-term storage. Evolutionary theory helps explain how we decide in advance what information will be useful. Memory allows both human and nonhuman animals to use information in ways that assist in reproduction and survival. For instance, recognizing a predator and remembering an escape route will help an animal avoid being eaten and thus give it an advantage over animals that fail to learn from their experiences. For humans, remembering which objects are edible, which people are friends and which ones are enemies, and how to get home are all critical for survival. The key is that this information must be deeply encoded into long-term storage for us to remember it.

eNCODING FOr LONG-terM StOraGe  We have seen that paying atten- tion to information allows it to be encoded into short-term storage. To store information more permanently, we also need to use attentional processing to encode that information into long-term storage.

long-term storage A memory storage system that allows

relatively permanent storage, probably of

an unlimited amount of information.

HoW Do We MAINTAIN MeMorIeS oVer TIMe?    ■    243

According to the levels of processing model, the more deeply an item is processed during encoding, the more meaning it has and the better it is remembered (Craik & Lockhart, 1972). Encoding can be achieved through two types of rehearsal. Maintenance  rehearsal, simply repeating the item over and over, provides shal- low encoding of information. This rehearsal is based on how the item sounds (auditory information). elaborative  rehearsal encodes the information more deeply. This rehearsal is based on meaning (semantic information). For example, we think about the item conceptually or decide whether it refers to ourselves. In other words, in this type of rehearsal, we encode information more deeply when it is meaningful to us and we can link it to knowledge already in our long-term stor- age. Contestants in the USA Memory Championship use elaborative encoding to remember playing cards by linking each card with a person, action, or object that the competitor knows.

How does encoding work, according to the levels of processing model? Suppose you show research participants a list of words and then ask them to do one of three things. You might ask them to make simple perceptual judgments, such as whether each word is printed in capital or lowercase letters. This task requires the processing of visual information. Or you might ask the participants to judge the sound of each word, such as whether the word rhymes with boat. This task calls for the processing of auditory information. Or you might ask them about each word’s meaning, as in “Does this word fit in the sentence They had to cross the _____ to reach the castle?” This task requires semantic processing. Once participants have completed the task, you might ask them to remember as many words as possible. You would find that words processed based on semantics, or meaning, are remembered the best (Figure  7.10). Brain imaging studies have shown that deep encoding based on semantics activates more brain regions than shallow encoding and that this greater brain activity is associated with better memory (Kapur et al., 1994). Together, these findings suggest that deeper encod- ing improves the likelihood of long-term storage, which then improves the likeli- hood of remembering.

You can see for yourself how encoding works according to levels of process- ing. Think back to that phone number mentioned earlier. Even if you used main- tenance rehearsal to repeat the phone number to yourself, you probably did not remember it. This failure to store the phone number in long-term storage shows how attention and memory function hand in hand: We attend just enough to complete the current task and lose information that seems irrelevant to us or insignificant.

Figure 7.10 Deeper encoding aids  Long-term  Storage If participants are asked to remember a

list of words based on how the words look,

how they sound, or what they mean, they

usually have better recall after processing

the meaning of the information. This result

suggests that deeper encoding aids

long-term storage.

Depth of encoding Shallow Medium Deep

Visual: what the word looks like

Auditory: how the word sounds

Semantic: what the word means

0

30

40

50

60

70

80

90

100

Percentage of words recalled

10

20

The more deeply the material is encoded, the better it is remembered.

maintenance rehearsal Using working memory processes to

repeat information based on how it sounds

(auditory information); provides only

shallow encoding of information and less

successful long-term storage.

elaborative rehearsal Using working memory processes to

think about how new information relates

to ourselves or our prior knowledge

(semantic information); provides deeper

encoding of information for more

successful long-term storage.

244    ■    Chapter 7  MeMory

Now suppose you are reminded of the number, 463-5456. You also learn that this is the phone number of a potter, who chose the last four digits, 5456, because they correspond to the letters KILN, which is an oven used in pottery making. Are you more likely to remember the number? If so, your ability to remember is increased because you are using elaborative rehearsal to encode the informa- tion more richly. You are encoding not just on visual or auditory information about the number but on semantic information about the word KILN. In fact, you might have used a combination of both visual and semantic encoding, called dual coding, which is a very successful method of transferring the information into long-term storage.

LONG-terM StOraGe verSUS ShOrt-terM StOraGe By now it should be clear that long-term storage differs from short-term storage in several ways. Long- term storage lasts longer and has a far greater capacity, and it depends on deep encod- ing of information. But is long-term storage truly a different type of memory than short-term storage?

Some evidence that short-term storage and long-term storage are separate systems comes from research that required people to recall a long list of words. The ability to recall items from the list depended on the order of presentation. That is, people remembered items presented early or late in the list better than items in the middle of the list. The primacy effect refers to the better memory people have for items presented at the beginning of the list. The recency effect refers to the better memory people have for the most recent items, the ones at the end of the list (Figure 7.11).

One explanation for the primacy and recency effects relies on a distinction between short-term storage and long-term storage. When research participants study a long list of words, they rehearse the earliest items the most. As a result, that information is transferred into long-term storage. By contrast, the last few items are still in short-term storage when the participants have to recall the words immediately after reading them. This research suggests that primacy effects are due to retrieving information from long-term storage, whereas recency effects are due to retrieving information from short-term storage.

Figure 7.11 primacy and recency effects This graph illustrates the primacy

effect: People have better memory

for items at the beginning of a

list because those items are in

long-term storage. The graph

also illustrates the recency effect:

People have better recall for items

at the end of a list because those

items are still in short-term storage.

These effects indicate that there is

a difference between short-term

storage and long-term storage.

Probability of recall

0%

100%

50%

First word Last wordSerial position of each word in list 1 5 10 15 20 25

Primacy effect: People have a good memory for items at the beginning of a list.

Recency effect: People also have a good memory for items at the end of a list.

Re�ects long-term storage

Re�ects short-term storage

HoW Do We MAINTAIN MeMorIeS oVer TIMe?    ■    245

Our Long-Term Storage Is Organized Based on Meaning Imagine if a library put each of its books wherever there was empty space on a shelf. To find a particular book, a librarian would have to look through the entire inventory book by book. This type of random storage would not work well for books, and it would not work well for memories. When an event or some information is important enough, you want to be able to retrieve it later. How is information organized for long-term storage so it is easy to retrieve later on?

As we discussed in Chapter 5, our sensory experiences are transformed by our brains into our perceptions of those experiences. For instance, when your visual system senses a shaggy, four-legged animal and your auditory system senses bark- ing, you perceive a dog. But you do not have a tiny picture of a dog stored in your head. Instead, the concept of “dog ” is a mental representation for a category of animals that share certain features, such as having fur and barking. The mental representation for “dog ” differs from that for “cat,” even though the two are simi- lar in many ways. You also have mental representations for complex and abstract ideas, including beliefs and feelings. What all of the representations have in common is that they include semantic information about the concepts and what those concepts mean to you. Long-term storage is based on the meaning of these semantic mental representations.

SCheMaS If we maintain memories in long-term storage according to their meaning, how do we determine the meanings of particular memories? Chunking is a good way to encode groups of items for long-term storage. The more meaning- ful the chunks, the better we will store them and remember them. Decisions about how to chunk information depend on schemas, ways of structuring memories in long-term storage that help us perceive, organize, process, and use information. As we sort out incoming information, schemas guide our attention to the relevant features. Thanks to schemas, we can construct new memories by filling in holes within existing memories, overlooking inconsistent information and interpreting meaning based on our experiences.

Although schemas help us make sense of the world, they can lead to biased encoding. In a classic demonstration conducted in the early 1930s, the psycholo- gist Frederic Bartlett (1932) asked British participants to listen to a Canadian First Nations folktale. The story involved supernatural experiences, and it was difficult to understand for those unfamiliar with such tales. Fifteen minutes later, Bartlett asked the participants to repeat the story exactly as they had heard it. The partic- ipants altered the story greatly. They also altered it consistently, so that it made sense from their own cultural standpoint, or schema. Sometimes they simply forgot the supernatural parts they could not understand. In other words, pieces of information that do not fit into our preexisting schemas can be hard to encode into long-term storage.

In addition, schemas also affect your ability to retrieve information from long- term storage. Read the following paragraph carefully:

The procedure is actually quite simple. First arrange things into different bundles depending on makeup. Don’t do too much at once. In the short run this may not seem important, however, complications easily arise. A mistake can be costly. Next, find facili- ties. Some people must go elsewhere for them. Manipulation of appropriate mechanisms should be self-explanatory. Remember to include all other necessary supplies. Initially the routine will overwhelm you, but soon it will become just another facet of life. Finally,

246    ■    Chapter 7  MeMory

rearrange everything into their initial groups. Return these to their usual places. Eventu- ally they will be used again. Then the whole cycle will have to be repeated. (Bransford & Johnson, 1972, p. 722)

Now, can you say what this paragraph was specifically about? You probably cannot say exactly. If you can’t say what it was about, do you think you will remem- ber it well or be able to answer questions about it? What if we tell you that the para- graph is describing washing clothes. Go back and reread the paragraph. Notice how your schema for doing laundry can help you understand and remember how the words and sentences are connected to one another. In a research setting, college students who read this paragraph knowing that it was about washing clothes found it easy to understand and relatively straightforward to recall. In short, having a schema about information can help you remember it later on.

aSSOCIatION  NetWOrKS Another way that the meaning of information is organized in long-term storage is based on networks of associations. In a network model proposed by the psychologists Allan Collins and Elizabeth Loftus (1975), an item’s distinctive features are linked in a way that identifies the item. Each unit of information in the network is a node. Each node is connected to many other nodes. The resulting network is like the linked neurons in your brain, but the nodes are simply bits of information, not physical objects (Figure 7.12). For example, when you look at a fire engine, all the nodes that represent a fire engine’s features, such as “red,” are activated. The resulting activation pattern across nodes gives rise to the knowl- edge that the object is a fire engine rather than, say, a car, a vacuum cleaner or a cat.

An important feature of network models is that activating one node increases the likelihood that closely associated nodes in the same category will also be activated. As shown in Figure 7.12, the closer the nodes, the stronger the association between them and therefore the more likely it is that activating one node will activate the other. Seeing a fire engine activates linked nodes, so you will quickly recognize other vehicles, such as “ambulance.” In fact, you will recognize vehicles more quickly than you will recognize items in other categories, such as an apple, which is a fruit.

The main idea here is that activating one node increases the likelihood that closely linked nodes will become active. This idea is central to spreading

Figure 7.12 a Network of associations Memories are organized in

long-term storage based on

the meaning of information.

Concepts are connected through

their associations. The closer the

concepts are to each other, the

stronger the association between

them. Activation of a concept

(fire engine) spreads to close

associates and activates them

(dark lines). But far associates

become only weakly activated

(lighter lines).

Red

Rose

Apple

Cherry

Sunset

Sunrise Cloud

Pear

Orange

Yellow

Green

An item’s characteristics and associates are strongly linked to it.

The farther the nodes, the weaker the association will be.

Activating one node increases the likeli- hood that closely associated nodes will also be activated.

Truck

Ambulance

Fire engine

Bus

Vehicle Street

Car

7.3 What Are Our Different Long-Term Storage Systems?

WHAT Are oUr DIFFereNT LoNG-TerM STorAGe SySTeMS?    ■    247

■ A huge amount of visual, auditory, taste, smell, and touch information is

maintained in sensory storage for up to a few seconds to ensure continuous

sensory experiences.

■ Short-term storage keeps about 8 items available for current use for up to 20

seconds. Active processing in working memory increases both this capacity

and this duration.

■ Long-term storage of memories is relatively permanent and virtually limitless

for deeply encoded information.

■ Information in long-term storage is organized based on meaning through

schemas and association networks.

7.2  CheCKpOINt:  How Do We Maintain Memories Over Time?

LearNING GOaLS    reaDING aCtIvItIeS

a. remember the key terms about long-term storage

systems and brain processes.

List all of the boldface words and write down their

definitions.

b. Apply the two forms of explicit memory to your life

and explain whether they are affected by retrograde

amnesia.

Provide an example of an episodic memory and a semantic

memory you have, and explain whether you would recall

them if you developed retrograde amnesia today.

c. Understand implicit memory and whether anterograde

amnesia affects it.

explain whether a person with anterograde amnesia

could or could not learn a new motor task, such as riding

a bicycle.

d. Understand how the brain processes memories. Summarize in your own words the brain areas that

contribute to explicit memory and implicit memory.

activation models of memory. According to these models, information that is heard or seen activates specific nodes for memories in long-term storage. This activation increases the ease of access of stored information to linked material. Easier access of stored information means easier retrieval.

Think about the huge amount of material in your memory. It is amazing how quickly you can search through that long-term storage and obtain the memo- ries you need. Each time you hear a sentence, you have to remember what all the words mean. You also have to recall all the relevant information that helps you understand the sentence’s overall meaning. For this process to occur, the informa- tion needs to be organized logically. Imagine trying to find a specific file on a full 600-gigabyte hard disk by opening one file at a time. Searching that way would be hopelessly slow. Instead, most computer disks are organized into folders, within each folder are more-specialized folders, and so on. Associative networks in the brain work similarly. The network is organized by category. Because the categories are structured in a hierarchy, they provide a clear and explicit blueprint for where to find needed information quickly.

248    ■    Chapter 7  MeMory

retrograde amnesia A condition in which people lose the

ability to access memories they had

before a brain injury.

anterograde amnesia A condition in which people lose the ability

to form new memories after experiencing

a brain injury.

Retrograde amnesia: poor memory for events that occurred before brain injury

Anterograde amnesia: poor memory for events occurring after brain injury

Older memories Newer memories

Time

Point in time when brain damage occurs

Older memories Newer memories

Time

Point in time when brain damage occurs

(a)

(b)

Figure 7.15 retrograde and anterograde amnesia Amnesia involves two forms of memory loss. (a) retrograde amnesia is an inability to access memories that were created before the brain damage (see red X). (b) Anterograde amnesia is an inability to create new memories after the brain damage (see red X).

Figure 7.14 Surgery on h.M.’s Brain The portions of the medial temporal lobe

that were removed from H.M.’s brain are

indicated by the blue regions.

Frontal lobe

Underside of brain

Temporal lobe

Spinal cord

Henry Molaison, one of the most famous people in memory research, was born in 1926 and died in 2008 (Figure  7.13). In vital ways, though, his world stopped in 1953, when he was 27 years old. As a young man, Molaison suffered from severe epilepsy, which caused seizures that made it impossible for him to lead a normal life. Molaison’s seizures originated in the temporal lobes of his brain and spread from there to other parts of the brain. Because the anticonvulsive drugs available at that time could not control his seizures, surgery was the only choice for treat- ment. The reasoning behind this surgery was that if the seizure-causing portion of his brain was removed, he would stop having seizures. So in September 1953, Molaison’s doctors removed parts of his medial temporal lobes, the area in the middle of the temporal lobes, including the hippocampus (Figure 7.14).

The surgery quieted Molaison’s seizures, but it had an unexpected and very unfor- tunate side effect: He lost the ability to store most types of new information in long- term storage. This condition, called amnesia, includes two basic types. In retrograde  amnesia, people lose memories for past events, facts, people, and even personal infor- mation (Figure 7.15a). By contrast, in anterograde amnesia, people lose the ability to form new memories (Figure 7.15b). After his surgery, Molaison experienced antero- grade amnesia. Until his death, the larger world did not know Molaison’s real name or what he looked like. His privacy was guarded by the researchers who studied how anterograde amnesia affected his memory abilities. But the knowledge provided by this research with Molaison (known as H.M.) is the basis for what we know about the types of memories in long-term storage.

An older view of memory was that all memories were basically the same type. In the late 1970s and early 1980s, cognitive psychologists began to challenge this view. They argued that memory is not just one thing. Rather, they saw it as a process that involves several interacting systems

Figure 7.13 henry Molaison (h.M.) Known to the world only by his initials,

Molaison became one of the most famous

people in memory research by participating

in countless experiments. He died at a

nursing home on December 2, 2008.

WHAT Are oUr DIFFereNT LoNG-TerM STorAGe SySTeMS?    ■    249

This graphic will help you remember the relationship between the two main types of memory in long-term storage and

the subtypes.

LearNING tIp: Remembering the Types of Memory in Long-Term Storage

Associating two stimuli elicits a response.

Example: Your dentist uses a drill on your teeth, and it hurts, so next time you are afraid of the dentist.

Example: You are able to play the piano.

Motor skills and habitsPersonally experienced events

Example: You got a great present on your last birthday.

Facts and knowledge

Example: A tomato is a fruit, not a vegetable.

Episodic memory Procedural memory

Semantic memory

Requires conscious effort and often can be verbally described…

Does not require conscious effort and often cannot be verbally described…

Explicit memory Implicit memory

Long-term storage

Classical conditioning

(Schacter & Tulving, 1994). The systems have a common function: to retain and use information. However, they encode and store different types of information in different ways. Research on H.M.’s memory abilities in the past few decades has been critical in helping us understand that long-term storage is actually made up of several memory systems. Specifically, H.M. showed us that brain damage can affect memories that we intentionally retrieve and describe: These are called explicit memories. However, brain damage may not affect memories that we display by our behavior, such as how to ride a bike. These are called implicit memories. These two types of memories, along with their subtypes, are shown in the Learning Tip.

Our Explicit Memories Involve Conscious Effort According to the psychologists who tested H.M., his IQ was slightly above aver- age. His thinking abilities remained intact after his surgery. He could hold a normal conversation as long as he was not distracted, though he forgot the conversation in a minute or less. H.M.’s ability to hold a conversation showed that he was still able to remember things for short periods. After all, to grasp the meaning of spoken language, a person needs to remember the words recently spoken, such as the beginning and end of a sentence. So his short-term storage was intact.

In addition, after the surgery, H.M. could still talk about things he knew at the time of the surgery. He could describe members of his family and memories from his childhood, explain the rules of baseball, and so on. So H.M. could clearly access information that was already in long-term storage at the time of the surgery. After the surgery, however, H.M. could not encode new memories in long-term storage. He never remembered what day of the week it was, what year it was, or his own age. People who worked with H.M.—such as the psychologist Brenda Milner, who

250    ■    Chapter 7  MeMory

followed his case for over 40 years—had to introduce themselves to him every time they met. Because of his profound memory loss, he remembered nothing from minute to minute. As H.M. put it, “Every day is alone in itself.”

aMNeSIa aND eXpLICIt MeMOrY The study of H.M.’s anterograde amnesia helped researchers discover that different memory systems are associated with long-term storage. A type of memory we can intentionally retrieve and describe is called explicit  memory. For example, try to answer these questions: What did you eat for dinner last night? What does the word aardvark mean? In trying to answer these questions, you used explicit memory. You can declare these memo- ries in words, so explicit memory is sometimes called declarative memory. Explicit memories can involve words or concepts, visual images, or both. Most of the exam- ples presented in this chapter so far involve the explicit memory system.

Though H.M. could access explicit memories that were stored before his surgery, he could not store any new explicit memories after the surgery. The fact that his anterograde amnesia affected this ability suggests that regions in the medial temporal lobe that were removed during the surgery are critical for long-term stor-

age of new explicit memories. Further research has shown that there are actually two main types of explicit memories: semantic and episodic.

epISODIC aND SeMaNtIC MeMOrY In 1972, Endel Tulving observed that people have two types of explicit memory: episodic memory and seman- tic memory. episodic  memory refers to our personal experiences and includes information about the time and place each experience occurred (Figure  7.16a). Memories of where you were and what you did on your sixteenth birthday, for example, are part of your episodic memory. Semantic  memory  is our knowledge of facts independent of personal experience. We might not remember where or when we learned a fact, but we know it (Figure 7.16b). For instance, most people know what Jell-O is. They know the capitals of places they have never visited. Even people who have never played baseball know that three strikes mean the batter is out.

Scientists have learned a great deal about memory by studying people like H.M. and others who have impaired memory. Evidence that episodic and semantic systems of explicit memory are separate can be found in cases of brain injury in which a person’s semantic memory is intact even though episodic memory is impaired. Researchers found this pattern in three British people who had experienced brain damage as children ( Vargha-Khadem et al., 1997). Each of the three developed poor memory for episodic information. As children, they had trouble reporting what they had for lunch, what they had watched on television 5 minutes earlier, or what they did during summer vacation. Their

parents reported that the children had to be constantly monitored to make sure they remembered things as basic as going to school. Remarkably, these three children attended mainstream schools and did reasonably well. Moreover, when tested as young adults, their IQs fell within the normal range. They learned to speak and read, and they could remember many facts. For instance, one of the three, at age 19, was asked, “Who is Martin Luther King Jr.?” The person answered, “An American; fought for Black rights, Black rights leader in the 1970s; got assas- sinated.” In other words, despite their brain damage, these people were able to encode and retrieve semantic memories from long-term storage. But they could not remember their own personal experiences.

explicit memory The system for long-term storage of

conscious memories that can be verbally

described.

episodic memory A type of explicit memory that includes a

person’s personal experiences.

semantic memory A type of explicit memory that includes a

person’s knowledge about the world.

Figure 7.16 two types of explicit Memory  (a) one type of explicit memory is episodic memory. episodic memory

enables people to recall and describe

their prior experiences, as these veterans

are doing. (b) Another type of explicit memory is semantic memory, a person’s

knowledge of facts. Game shows such

as Jeopardy! test semantic memory. In 2004, Ken Jennings (pictured here)

became the longest defending champion

on Jeopardy! when he won 75 games in a row.

WHAT Are oUr DIFFereNT LoNG-TerM STorAGe SySTeMS?    ■    251

Figure 7.17 h.M.’s performance in Mirror Drawing When H.M. got better at mirror drawing

over time, he showed that he could form

new implicit memories (procedural)

after his surgery. When he could not

remember doing the mirror drawing task,

H.M. showed that he could not form new

explicit memories (episodic) after his

surgery. These findings are evidence for

the existence of multiple memory systems

in long-term storage.

implicit memory  The system for long-term storage of

unconscious memories that cannot be

verbally described.

procedural memory A type of implicit memory that involves

motor skills and behavioral habits.

Our Implicit Memories Function Without Conscious Effort We have seen that after his surgery H.M. could not form new explicit memories. Let’s explore H.M.’s memory abilities a bit more to see how they reveal the existence of a second form of memory: implicit memory.

H.M. was able to learn some new things after his surgery, such as motor tasks. But he could not state that he had learned these things. In one series of tests, he was asked to trace the outline of a star while watching his hand in a mirror (Figure 7.17). Most people do poorly the first few times they try this difficult task. On each of three consecutive days, H.M. was asked to trace the star 10 times. His performance improved over the three days. This finding indicated that he had retained some information about the task. Given his deficits in explicit memory, H.M. could not recall ever having performed the task previously. Nevertheless, his ability to learn new motor skills enabled him to get a job at a factory. There, he mounted cigarette lighters on cardboard cases.

IMpLICIt  MeMOrY  aND  aMNeSIa H.M.’s retained memory abilities after the surgery reveal a second memory system for long-term storage. This system contrasts with H.M.’s deficits in explicit memory. Implicit  memory refers to memories that we are not conscious of. Because you cannot declare implicit memories in words, this system is sometimes called non- declarative memory. Implicit memory influences our lives in subtle ways. For example, adver- tisers rely on implicit memory to influence our purchasing decisions. Constant exposure to brand names makes us more likely to think of them when we buy prod- ucts. If you find yourself wanting a particular brand, you might be unconsciously remembering advertisements for that brand, even if you cannot recall the specifics.

Because H.M. could form new implicit memories after the surgery, his behavior suggests that parts of the medial temporal lobe that were removed are not neces- sary for storing these types of memories. This idea further suggests that implicit memory is a second unique long-term storage system. Furthermore, there are two main types of implicit memories: classical conditioning and procedural memories.

CLaSSICaL  CONDItIONING  aND  prOCeDUraL  MeMOrY Implicit mem o ries do not require conscious attention. They happen automatically, without deliberate effort. There are two main types of implicit memory. Classical condi- tioning, which we discussed in Chapter 6, employs implicit memory (Figure 7.18a). For example, if you always experience fear at the sight of a person in a white lab coat, you might have past associations between a person in a white lab coat and pain. This memory is implicit.

Suppose you are driving. Suddenly, you realize you have been daydreaming and have no episodic memory of the past few minutes. During that time, you employed implicit memories of how to drive and where you were going. Because you drew on that information, you did not crash the car or go in the wrong direction. This type of implicit memory is called procedural memory (Figure 7.18b). It involves motor skills, habits, and other behaviors employed to achieve goals, such as coordinating muscle movements to ride a bicycle or following the rules of the road while driving.

252    ■    Chapter 7  MeMory

Procedural memories are generally so unconscious that most people find that consciously thinking about automatic behaviors interferes with the smooth produc- tion of those behaviors. The next time you are riding a bicycle, try to think about each step involved in the process. How does that conscious effort affect the action?

Procedural memories tend to last a long time. Once you learn to ride a bike, you most likely will always be able to ride one. It would take brain damage for you to lose that skill.

Prospective Memory Lets Us Remember to Do Something “When you see Juan, tell him to call me, okay? And don’t forget to bring the DVD tonight so we can watch the movie.” Unlike the other types of memory we have discussed so far, prospective  memory is future oriented. It means that we will remember to do something at some future time (Graf & Uttl, 2001).

Prospective memory comes with a cost. Recall that the cognitive effort involved in paying attention to certain information makes us unable to attend closely to other information. In the same way, remembering to do something takes up valuable cognitive resources. This type of memory reduces either the number of items we can deal with in short-term storage or the number of things we can attend to and process in working memory (Einstein & McDaniel, 2005).

In a study of prospective memory, participants had to learn a list of words (Cook, Marsh, Clark-Foos, & Meeks, 2007). In one condition, the participants also had to remember to do something. For example, they had to press a key when they saw a certain word. That group—the participants who had to remember to do something—took longer to learn the list than the control group that learned the same list of words but did not have to remember to do something.

Cues can help prospective memory. For example, seeing Juan might automati- cally trigger your memory. You would then effortlessly remember to give Juan the message. But particular environments do not always have obvious cues for certain prospective memories. So you might not encounter a cue for remembering to bring the DVD. Prospective memory for events without cues is the reason sticky notes are so popular (Figure 7.19a). In this case, you might stick a note that says “Bring DVD” on the steering wheel of your car. By jogging your memory, the note saves you the effort of remembering. For an even more urgent reminder, you might set your cell phone alarm or use an electronic calendar (Figure 7.19b).

prospective memory  remembering to do something at some

future time.

Figure 7.18 two types of Implicit Memory (a) one type of implicit memory includes classical conditioning. For example, a

person may learn to associate a stimulus,

such as a spider, with a certain response,

such as fear. (b) A second type of implicit memory is procedural memory, or motor

memory. This type includes knowing how

to ride a bicycle or play the piano.

Figure 7.19 prospective Memory People use several tools to assist

prospective memories. (a) Some of us use sticky notes to remind us to do

things. (b) Some of us use a device, such as a smartphone, to remember

appointments and deadlines. (a) (b)

(a)

(b)

WHAT Are oUr DIFFereNT LoNG-TerM STorAGe SySTeMS?    ■    253

Memory Is Processed by Several Regions of Our Brains Over the past twenty years, memory researchers have made tremendous progress in understanding what happens in the brain when we acquire, store, and retrieve memories. The research on people with memory disorders clearly reveals that there are separate long-term storage systems. Moreover, distinct brain regions are involved in processing information pertaining to different long-term stores.

MeMOrY’S phYSICaL LOCatIONS Not all brain areas are equally involved in memory. A great deal of specialization occurs. In fact, different brain regions are responsible for stor- ing different aspects of information (Figure 7.20).

Recall that H.M.’s anterograde amnesia left him unable to learn new explicit memories. However, he remained able to learn new implicit memories. H.M.’s surgery removed regions within the temporal lobes, such as the hippocampus. Clearly, this area is important for the ability to store new explicit memories. However, the temporal lobes are less important for implicit memories such as procedural memories and classical conditioning.

By contrast, the cerebellum plays a role in implicit memory systems. It is especially involved in procedural memory for learning motor actions. The amyg- dala is especially important for another type of implicit memory. Recall that in classical conditioning, an animal may unconsciously learn to be afraid of some- thing. But an animal without an amygdala cannot learn to fear objects that signal danger.

The take-home message here is that memory does not “live” in one part of the brain. Memory is distributed among different brain regions. So if you lose one particular brain cell, you will not lose a memory.

CONSOLIDatION  OF  MeMOrIeS Your brain is different than it was before you began reading this chapter. Reading the chapter is making some of your neural connections stronger. At the same time, new neural connections should be developing—especially in your hippocampus. Neural connections that support memory have become stronger, and new synapses have been constructed (Miller, 2005). This process is known as consolidation. Through consolidation, your expe- riences become your lasting memories.

The medial temporal lobes are responsible for coordinating and strength- ening the connections among neurons when we learn something. This region, including the hippocampus, is particularly important for the formation of new memories. The actual storage of memories, however, occurs in the particular brain regions engaged during the perception, processing, and analysis of the material being learned. For instance, visual information is stored in the corti- cal areas involved in visual perception. Sound is stored in the areas involved in auditory perception. Now think about memories of those sensory experiences. Remembering something we have seen or heard involves reactivating the same cortical circuits that were involved when we first saw or heard the informa- tion (Figure 7.21). It is almost as if the brain is reexperiencing what we saw or heard. This reexperience occurs even though the original stimulus is no longer in front of us.

consolidation A process by which immediate memories

become lasting through long-term storage.

Figure 7.20 Brain regions associated With   Memory We all have several different memory

systems for long-term storage. Specific

brain regions are responsible for

processing information for each of the

long-term stores.

Hippocampus (spatial memory)

Prefrontal cortex (working memory)

Temporal lobe (explicit memory)

Cerebellum (implicit memory: procedural memory)

Amygdala (implicit memory: fear learning)

254    ■    Chapter 7  MeMory

The medial temporal lobes are important for coordinating the storage of information between the different cortical sites and also are involved in strengthening the connections between these sites (Squire, Stark, & Clark, 2004). Think about what Google does for the Internet. Google doesn’t store all the informa- tion on the Internet, but it provides links to where that information is stored. That’s what the medial temporal lobes do for memories. Once the connections between different brain sites are strengthened sufficiently, the medial temporal lobes become less important for memory. H.M.’s surgery removed parts of his medial temporal lobes. Without those parts, he could not make new memories (at least ones he could talk about). He still was able to retrieve old memories.

To understand the basic consolidation process, consider this example. While reading this chapter, you have come to understand that medial means “in the middle.” Now that you have acquired this information, you need to think about it over time so that it will be consolidated in your memory. A good night’s sleep might also help this process. There is compelling evidence that sleep helps with the consolidation of memories and that disturbing sleep interferes with learning.

reCONSOLIDatION OF MeMOrIeS  All of us have probably wished we could forget some things that are particularly embarrassing or painful. Could we actually do that?

A theory developed by Karim Nader and Joseph LeDoux proposes that once memories are activated, they need to be consolidated again for long-term stor- age (LeDoux, 2002; Nader & Einarsson, 2010). This process is known as recon- solidation. When memories for past events are retrieved, those memories can be affected by new circumstances, so reconsolidated memories may differ from their original versions (Nader, Schafe, & LeDoux, 2000). In other words, our memories begin as versions of what we have experienced, but they might change when we use them.

To understand how reconsolidation works, think of a student working with her textbook. Then the student returns the book to its place on her bookshelf so that she can refer to it later. While working, the student might turn down the edges of the pages she uses most frequently. When she retrieves the book later, it might naturally open to those pages. What if some pages become damaged to the point of falling out? If the student looks for those pages later, she won’t be able to find them. The idea here is that the book placed back on the shelf is now different from the one the student started with. The dog-eared pages make some information easier to access, and the damaged pages make other information impossible to access. Reconsolidation actually changes our memories every time we access them.

According to this theory, reconsolidation occurs each time a memory is acti- vated and placed back in storage. This process may explain why our memories for events can change over time. Think about another intriguing possibility:

Figure 7.21 Brain activation During perception  and remembering These four horizontally sliced brain images

were acquired using magnetic resonance

imaging. In each pair, the top image shows

the brain activity for sensory-specific

perception. The bottom image shows

the regions of the sensory cortex that

are activated when that sensory-specific

information is remembered. Notice that

the perceptions and the memories both

activate similar cortical areas.

Brain regions active during the perception of pictures

Brain regions active during the perception of sounds

Brain regions active when those same sounds are remembered

Brain regions active when those same pictures are remembered

WHAT Are oUr DIFFereNT LoNG-TerM STorAGe SySTeMS?    ■    255

Figure 7.22 altering Memories In the 2004 movie Eternal Sunshine of the Spotless Mind, Joel Barish (played by Jim Carrey) undergoes a procedure that eliminates memories

of his former girlfriend. The movie is fiction, but real-life researchers are

investigating how using behavioral techniques or drugs can alter memories.

Halfway into his first semester at college, James was feeling

confident. He had learned a lot and received good grades on

his midterm exams. When he checked Facebook to see how his

friends were, he was especially happy to find out that his friend

Lorenzo was doing well at his university. James and Lorenzo

had been friends since they were little boys, when they met at

Little League. They had joined the same Boy Scout troop and

moved up the ranks to eagle Scout together. But their senior

year had been difficult: Lorenzo’s mother was killed in a car

crash. She had been driving, and Lorenzo was in the passenger

seat. Lorenzo had been haunted by powerfully negative memo-

ries of that day, and he went through a period where he just

wasn’t himself. With some help from a psychologist, Lorenzo

had improved. Although James had hoped they would go to

the same university, he was simply glad that his friend was

functioning well enough to attend college and even enjoy it.

James took a break from his computer and started read-

ing Chapter 7 of his psychology textbook. Thinking about

memory made him wonder, Will Lorenzo ever forget the details of that crash? Is there a technique for erasing memo- ries? So many conditions can be treated with medication now. Will we ever be able to just pop a pill and forget something we don’t want to remember? Curious but expecting to find nothing, James did an Internet search for “pill for losing a

memory.” At the online version of Wired magazine, he found an article that actually described how such a pill would work.

Can an article on the Internet really be trusted? This one seemed quite informative. The writer had even interviewed

the researchers, rather than just relying on a journalistic point

of view. This piece was reporting, not an editorial.

The article covered a lot of the same material that James

had just read about how memories are formed. As James

knew from his textbook reading, memories are not set in

stone. every time we access them, they are altered ever

so slightly. According to the Wired article, this kind of change helps explain the success of talk therapy. Right! Talking about his memories helped Lorenzo. In talk ther- apy, a patient can discuss painful memories in a controlled,

safe space with the help of a therapist. When the painful

memories are recalled in a less threatening way, the memo-

ries themselves can become less threatening. That is, they

are associated with less negative emotions. Lorenzo hasn’t forgotten the car crash, but it doesn’t seem to bother him the way it used to. But what if he could just get rid of that memory?

The article described a molecule, PKMzeta, that exists

in synapses. When this molecule was not present, some

memories apparently disappeared. researchers had found

drugs that blocked the activity of PKMzeta. Through test-

ing, the researchers were able to inhibit this molecule so

that specific memories were deleted but other attached

memories were not. The research had been done only on

rats, and other research contradicts these findings. But in

the future, with more testing, researchers may develop pills

that let us choose to erase some specific memories that we

want to stop recalling.

QUeStIONS James learned that it might be possible to change people’s

memories. What sort of ethical issues do you believe need

to be considered in altering memory? Are painful memo-

ries a part of being human, such as in helping people learn

from bad experiences? When would changing memories be

justified?

BeING a CrItICaL CONSUMer:  Can That Memory Be Erased?

Could bad memories be erased by activating them and then interfering with reconsolidation of them (Figure  7.22)? Recently, researchers have shown that using the classical conditioning technique of extinction during the period when memories are susceptible to reconsolidation can be an effective method of altering bad memories (Schiller et al., 2010; for a discussion of extinction, see Chapter 6).

256    ■    Chapter 7  MeMory

■ Amnesia is a deficit in long-term storage. retrograde amnesia is the inability

to recall past memories. Anterograde amnesia is the inability to form new

memories.

■ explicit memories that we consciously remember include personal events

(episodic memory) and general, factual knowledge (semantic memory).

■ Implicit memories are processed without conscious effort and include

classical conditioning and procedural memories of motor skills.

■ Prospective memory is remembering to do something in the future, and it has

“costs” in terms of reducing attentional resources and impairing short-term

storage and working memory processing.

■ Multiple brain regions process memory information. Through consolidation,

immediate memories become lasting memories. Memories may be altered

through reconsolidation.

7.3  CheCKpOINt:  What Are Our Different Long-Term Storage Systems?

retrieval cue Anything that helps a person access

information in long-term storage.

7.4 How Do We Access Our Memories?

Scott Hagwood and the other USA Memory Championship contestants are able to store large amounts of information in their brains by using various process- ing techniques. But when it comes time to compete, how do they actually “remember” the information? How do they get the information out of storage?

Up to this point, we have focused on two phases of memory. In the first phase, we acquire memories through encoding. In the second phase, we maintain infor- mation through storage in one of three memory storage systems. The third phase of processing information is to re-access the stored memories at a later date to use that information in some way. Four processes affect our ability to access stored memories, as shown in the Learning Tip.

Retrieval Cues Help Us Access Our Memories Encountering stimuli can automatically trigger memories. So a retrieval cue can be anything that helps us access a memory. Think about the smell of turkey, a favorite

LearNING GOaLS    reaDING aCtIvItIeS

a. remember the key terms about how we access

memories from long-term storage.

List all of the boldface words and write down their

definitions.

b. Understand how retrieval cues improve access to

memories in long-term storage.

explain, in your own words, three ways that retrieval cues

can be used to retrieve memories in long-term storage.

c. Apply forgetting to your own long-term storage of

memories.

Demonstrate the three ways to forget memories in long-

term storage with one example of each from your own life.

d. Understand how memories in long-term storage can

become distorted.

Compare, in your own words, the five ways that memories

in long-term storage can become distorted.

HoW Do We ACCeSS oUr MeMorIeS?    ■    257

song from years past, a familiar building, and so on. The properties of any experience are encoded with a memory and can later aid retrieval of that memory.

CONteXt  aND  State  aID  retrIevaL The context of an event includes details such as the physical location, odors, and background music. That context is encoded along with the memory. As a result, the context produces a sense of famil- iarity that helps us retrieve the memory (Hockley, 2008).

In a dramatic research demonstration of this context-dependent memory effect, two groups of scuba divers learned lists of words. Some divers learned the words on land. Other divers learned the words under water (Godden & Baddeley, 1975; Figure 7.23a). Later on, both groups recalled the words better when they were in the same environment where they had learned them (Figure 7.23b). That is, when divers learned information on land, they recalled that information better on land than under water. When divers learned the words under water, they recalled them better under water than on land. This study confirms that when the person is in the same context where information was learned, the environment where learning took place provides a cue that aids access to the information.

Like physical context, internal cues, such as mood, are also encoded with a memory. When our internal states are the same during both encoding and retrieval, the situation can provide a retrieval cue that enhances access to a memory. This effect is known as state-dependent memory.

This graphic will help you remember the four processes that affect our ability to access stored memories.

LearNING tIp: Remembering the Ways We Access Stored Memories

Distortion

Anything that helps a person access a memory in long-term storage …

• interference• context-dependent memory • blocking

• absentmindedness• state-dependent memory

• mnemonics

Continual recurrence of unwanted memories from long-term storage

Memory is flawed in several ways …

Retrieval cues Persistence

The inability to retrieve a memory from long-term storage …

Forgetting

Processes that affect access of memories in long-term storage

including including including • memory bias • flashbulb memories

• misattribution

• suggestibility

• false memories

Figure 7.23 Context–Dependent Memory A unique study showed that the context

of a memory can help retrieve that

memory. (a) People learned lists of words either on land or under water. (b) Later on, they remembered more words if they

were tested in the same environment

where they had learned the words.

(a) (b) Test on land

Test under water

Mean number of words recalled

0

2

4

6

8

10

12

14

Study on land Study under water

258    ■    Chapter 7  MeMory

forgetting The inability to access a memory

from long-term storage.

Figure 7.24 Forgetting Curve research shows that when a person

repeatedly practices with nonsense

syllables, it takes her less time to relearn

them later on.

8 16 24 32 42 53 64 0

5

10

15

20

Research on this topic was inspired by the observation that people experienc- ing alcoholism often can’t find important objects, such as paychecks. They store the objects in safe places while they are drinking, but cannot remember the places when they are sober. The next time they are drinking, however, they may remember where they put the objects.

MNeMONICS  aID  retrIevaL Mnemonics are learning aids or strategies that use retrieval cues to improve access to memory. People often find mnemon- ics helpful for remembering items in long lists. For example, the USA Memory Championship contestants use mnemonics for their feats. One mnemonic, the method of loci, consists of associating items you want to remember with physical locations. The contestants use the method of loci to remember the order of playing cards by visualizing cards in certain locations on a mental walk through a familiar place.

You can practice techniques of this kind. You may not become a memory contest champion, but you can improve your ability to access memories in long- term storage. Suppose you want to remember a grocery list of items to buy from the store. First, you might visualize parts of the physical layout of some familiar location, such as your bedroom. Then you would associate the list of items to buy with certain places in the room. You might picture your open dresser drawer filled to the top with apples, a loaf of bread snuggled in your bed under a comforter, and a waterfall of milk flowing down your curtains. When you later need to remember the items, you would visualize your room and retrieve the information associated with each location.

We Forget Some of Our Memories Ten minutes after you see a movie, you probably remember plenty of the details. The next week, you might remember mostly the plot and the main characters. Years later, you might remember only the gist of the story. You might not remember having seen the movie at all. We forget far more than we remember. Forgetting is the inabil- ity to access memory from long-term storage. This inability is a normal, everyday experience.

The study of forgetting has a long history in psychology. In the late nineteenth century, the psychologist Hermann Ebbinghaus examined how long it took him to relearn lists of unfamiliar nonsense syllables (e.g., vut, bik, kuh). Ebbinghaus found that when he repeatedly practiced with the syllables, it took him less time to relearn them the next day. In other words, the more time he spent learning material, the less he forgot. His results are shown in a forgetting curve (Figure 7.24). Luck- ily, most of us do not need to memorize nonsense syllables. But Ebbinghaus’s general findings apply to meaningful material as well. You may remember very little of the Spanish or calculus you took in high school, but relearning these subjects would take you less time and effort than it took to learn them the first time. This finding is great news for students: When you

spend more time actively working with material to learn it, you will forget less of the material.

Most people feel bad about forgetting. They wish they could better recall the material they study for exams, the names of childhood friends, the names of all

What part of the college experience do most students particularly dislike?

There’s a good chance you said “exams.” Psychology can’t make exams

go away, but it can help make them easier to deal with. Here are some

tools that can help you study more effectively and remember information

more easily.

1.  Distribute learning. Though pulling an all-nighter is a college classic, cramming does not work. Six sessions of 1 hour each, spread over days or

weeks, are much better for learning than one 6-hour marathon because

you will store information better (Cepeda, Pashler, Vul, Wixted, & rohrer,

2006).

2.  process  deeply. When you are learning something new, do not just read or repeat the material. Shallow processing won’t help your memory.

Instead, think about the meaning of the material and how the concepts

are related to each other and to your life. Using deeper processing, such

as by making material personally relevant, is an especially good way to

remember it easily.

3.  practice  retrieval. To make your memories more durable, you need to practice retrieving the information you are trying to learn. In fact,

repeated testing is a more effective memory-building strategy than

spending the same amount of time rereading or reviewing information

you have already read (roediger & Karpicke, 2006). Answering practice

questions will help you remember the information during exams.

4.  Overlearn. With material in front of us, we are often overly confident that we “know” the information and believe we will remember it later.

But recognition is easier than recall. As a result, information in a book

might not be as accessible when the book is closed and you have to

answer questions about what you read. If you want to be able to recall

information, you need to put in extra effort when encoding the material.

even after you think you have learned it, test yourself by trying to recall the material a few hours and a few days after studying. Keep rehearsing

until you can recall the material easily.

5.  picture images. Creating a mental image is an especially good way to remember something. Visual imagery strategies include making a sketch

to help you link ideas to images, creating a flowchart to show how some

process unfolds over time, or drawing a concept map that shows the

relationships between ideas.

6.  Make  mnemonics. Whatever their goals for remembering, people employ many types of mnemonics. For example, how many days are

there in September? In the Western world, at least, most people can read-

ily answer this question thanks to the old jingle that begins “Thirty days

has September.” Another common type of mnemonic is the acronym, such as HoMeS to remember the great lakes (Huron, ontario, Michigan,

erie, and Superior). To use all of the strategies we’ve described, you

need to remember them. As a first step toward improving your study

skills, try to create an acronym to remember these six strategies, using

the first letter of each strategy: DPPoPM.

USING pSYChOLOGY 

IN YOUr LIFe:

How Can I Remember Information for Exams?

260    ■    Chapter 7  MeMory

seven dwarfs who lived with Snow White, what have you. But imagine what life would be like if you could not forget. Imagine, for example, walking up to your locker. You want to recall its combination. Instead, you recall the 10 or 20 combi- nations for all the locks you have ever used. A Russian newspaper reporter had nearly perfect memory. If someone read him a tremendously long list of items and he visualized the items for a few moments, he could recite the list, even many years later. But his memory was so cluttered with information that he had great diffi- culty functioning in normal society. This condition tortured him to the point that he eventually was institutionalized (Luria, 1968).

Not being able to forget is as maladaptive as not being able to remember. In this way, forgetting is a desirable and useful aspect of human memory. Forgetting may even be necessary for survival. Normal forgetting helps us remember and use important information. There are three main ways that we forget: interference, blocking, and absentmindedness.

INterFereNCe When Ebbinghaus studied nonsense syllables, he observed forgetting over time. Many early theorists argued that such forgetting results from the decay of the particular memory trace in a person’s brain. Some evidence does indicate that unused memories are forgotten. However, research over the last few decades has established that most forgetting occurs because of interfer- ence from other information. There are two types of interference.

In retroactive  interference, access to older memo- ries is impaired by newer memories. Say you’re about to take a psychology test. You study the psychology material, and then you study some history material. Your performance on the psychology test might suffer because the psychology material you studied first is harder to access due to interference from the history material you studied second (Figure 7.25a). By contrast, in proactive  interference, access to newer memories is impaired by older memories. In this case, when you take your psychology test, your performance on that test might suffer because you recall the older informa- tion that you studied first, the history material, not the newer information you studied second, the psychology material (Figure 7.25b).

BLOCKING You can’t recall the name of a favorite song. You forget the name of someone you are introduc- ing. You “blank” on some lines when acting in a play. This type of forgetting is called blocking. Blocking occurs when we are temporarily unable to remember some- thing. It is frustrating but common.

Roger Brown and David McNeill (1966) described another good example of blocking: the tip-of-the-tongue phenomenon. Here, people experience great frustration as they try to recall specific words. For instance, when asked to provide a word that means “patronage bestowed on a relative, in business or politics” or “an astronomical instrument for finding position,” people often struggle (Brown, 1991). Sometimes they know which letter the word begins with, how many syllables it has, and even what it sounds like. Even with these partial retrieval cues, they cannot pull the precise word into working memory. (Did you know the words were nepotism and sextant?)

(a)

(b)

Study psychology (older memories).

Time

Time

Study history (newer memories).

Take psychology test.

Study history (older memories).

Study psychology (newer memories).

Take psychology test.

Retroactive interference: Older memories are hard to access due to interference from newer information.

Proactive interference: Newer memories are hard to access due to interference from older information.

Figure 7.25  retroactive and proactive   Interference (a) retroactive interference occurs when retrieving old memories (here, psychology

material) is hard due to interference from

new memories (here, history material).

(b) Proactive interference occurs when retrieving new memories (psychology

material) is hard due to interference from

old memories (history material).

retroactive interference When access to older memories is

impaired by newer memories.

proactive interference When access to newer memories is

impaired by older memories.

HoW Do We ACCeSS oUr MeMorIeS?    ■    261

Blocking often occurs because of interference from words that are similar in some way, such as in sound or meaning, and that are repeatedly experienced. For example, you might repeatedly call an acquaintance Margaret although her name is Melanie. The tip-of-the-tongue phenomenon increases with age, perhaps because older people have more memories that might interfere.

aBSeNtMINDeDNeSS Absentmindedness is the inattentive or shallow encod- ing of events. The major cause of absentmindedness is failing to pay attention (Figure 7.26). For instance, you absentmindedly forget where you left your keys because, when you put them down, you were also reaching to answer your phone. You forget the name of a person you are talking with because, when you met him 5 minutes earlier, you were wondering where your keys went. You forget whether you took your vitamins this morning because you were deciding whether to study for your psychology test or your history test.

Recall that when prospective memory fails, you fail to remember to do something that you were planning to do. This form of absentmindedness often occurs because you are caught up in another activity. This lack of attention can have serious conse- quences. In the United States over the past decade, more than 300 children have died because they were left unattended in hot cars (49 died in 2010 alone). In many cases, the parent forgot to drop off the child at day care on the way to work. It is easy to imagine forgetting your lunch in the car, but your child? Fortunately, such incidents are rare, but they seem to be especially likely when the parent’s typical routine does not include day care drop-off duty. While the parent is driving, his or her brain shifts to “autopilot” and automatically goes through the process of driving to the workplace instead of stopping at day care first.

Our Unwanted Memories May Persist Sometimes you want to forget something but have difficulty doing so. persistence occurs when unwanted memories recur despite our desire not to have them. Some unwanted memories are so traumatic that they destroy the life of the individual who suffers from them.

One prominent example of persistence occurs in posttraumatic stress disorder (PTSD), in which people experience extremely stressful episodes after having had a traumatic experience. During a PTSD episode, they relive the traumatic experience. PTSD is a serious mental health problem, affecting 7 percent of people in the United States alone (Kessler et al., 2005). The most common causes of PTSD include events that threaten people or those close to them. For example, the unexpected death of a loved one, a physical or sexual assault, military combat, a car accident, a natural disaster, or seeing someone badly injured or killed can all lead to PTSD.

Considerable research is under way to produce drugs that will erase unwanted memories. One drug, propranolol, blocks norepinephrine receptors. If it is given right around the time of a traumatic experience, the memories and fear response for that event are reduced, and the effect lasts for months (Cahill, Prins, Weber, & McGaugh, 1994; Pitman et al., 2002). Drugs such as propranolol might have side effects, however. Alternatively, as we discussed earlier, extinction can be used during reconsolidation to yield similar results, potentially without side effects (Schiller et al., 2010).

Erasing memories leads to many ethical questions. If we can erase traumatic memories, should we remove only the memories of traumas that were beyond the sufferer’s control? Or should a person be treated for suffering a guilty conscience after an intentional malicious act? Will reducing memories to take the emotional sting out of life make us less human?

persistence The continual recurrence of unwanted

memories from long-term storage.

Figure 7.26 absentmindedness The celebrated musician yo-yo Ma

is pictured here with his $2.5 million

eighteenth-century cello. This instrument

was returned to yo-yo Ma after he

absentmindedly left it in a cab.

262    ■    Chapter 7  MeMory

Our Memories Can Be Distorted You may think that you remember everything about your senior prom just as it happened. But research has shown clearly that human memory provides less-than- accurate portrayals of past events. In fact, human memory is really quite flawed. In general, distortion occurs in memory in five ways: memory bias, flashbulb memo- ries, misattribution, suggestibility, and false memories.

MeMOrY  BIaS Memory bias is the changing of memories over time so that they become consistent with our current beliefs or attitudes. As one of psychology’s greatest thinkers, Leon Festinger (1987), put it: “I prefer to rely on my memory. I have lived with that memory a long time, I am used to it, and if I have rearranged or distorted anything, surely that was done for my own benefit.”

We tend to recall our past beliefs and past attitudes as being consistent with our current ones. Often, we revise our memories when they contradict our attitudes and beliefs. We also tend to remember events as casting us in prominent roles or favorable lights. We exaggerate our contributions to group efforts. We take credit for successes and blame failures on others. And we remember our successes more than our failures.

FLaShBULB  MeMOrIeS Do you remember where you were when you first heard about the Boston Marathon bombings (Figure  7.27a)? Some events lead to what Roger Brown and James Kulik (1977) termed flashbulb memories. These vivid memories seem like a flash photo, capturing the circumstances in which we first learned of a surprising and consequential or emotionally arousing event. In 1977, Brown and Kulik interviewed research participants about their memories of the assassination of U.S. president John F. Kennedy. The participants described these 14-year-old memories in highly vivid terms. The details included who they were with, what they were doing or thinking, who told them or how they found out, and what their emotional reactions were to the event. Flashbulb memories are an exam- ple of episodic memory. They are not like the problem of persistence, however. They are not recurring unwanted memories.

An obvious problem affects research into the accuracy of flashbulb memories. Researchers have to conduct a study immediately after an event occurs so they can compare the memories of people at different times. The explosion of the U.S. space shuttle Challenger, on January 28, 1986, provided a unique opportunity for research on this topic. Ulric Neisser and Nicole Harsch (1993) had 44 psychology students fill out a questionnaire the day the shuttle exploded. When they tested the students’ memories three years later, only three students had perfect recall. The rest were incorrect about multiple aspects of the situation. We are all likely to experience inaccurate flashbulb memories, even for traumatic events that we think we remember well, such as the attacks on the World Trade Center in 2001 (Figure 7.27b).

Other researchers have documented better memory for flashbulb experiences. For example, for three years after the airline hijackings and attacks on the World Trade Center and Pentagon on September 11, 2001, a study was conducted of more than 3,000 people across the United States (Hirst et al., 2009). Memories related to 9/11—such as where the person first heard about the attacks and her knowledge about the events—declined somewhat during the first year. Memory remained stable thereafter. As might be expected, people who were living in New York City on 9/11 had, over time, the most accurate memories of the World Trade Center attacks.

haS It happeNeD  

tO YOU? 

Absentmindedness

Have you ever experienced

absentmindedness? Maybe you

left one room to get something

from another, but completely

forgot what you wanted once

you were there. This type of

forgetting happens to all of us at

one time or another.

The easiest way to overcome

absentmindedness in a situation

like this is to go back to the

room where you were thinking

about getting that object. In fact,

if returning to the room jogs

your memory, then you have

experienced the effect of context

dependence as well.

distortion Human memory is not a perfectly accurate

representation of the past, but is flawed.

HoW Do We ACCeSS oUr MeMorIeS?    ■    263

People are more confident about their flashbulb memories than they are about their ordinary memories (Talarico & Rubin, 2003). Although flashbulb memories are not perfectly accurate, they are at least as accurate as memory for ordinary events. Any event that produces a strong emotional response is likely to produce a vivid, although not necessarily accurate, memory (Christianson, 1992). Or a distinctive event might simply be recalled more easily than a trivial event, however inaccurate the result. It is also possible that greater media attention to major events leads to greater exposure to the details of those events, thus encouraging better memory (Hirst et al., 2009).

MISattrIBUtION Misattribution occurs when we misremember the time, place, person, or circumstances involved with a memory. Source amnesia is a form of misattribution that occurs when we have a memory for an event but cannot remember where we encountered the information. Consider your earli- est childhood memory. How vivid is it? Are you actually recalling the event? How do you know you are not remembering either something you saw in a photograph or a story related to you by family members? Most people cannot remember specific memories from before age 3. The absence of early memories may be due to the early lack of language as well as to frontal lobes that are not fully developed.

An intriguing example of source misattribution is cryptomnesia. Here, we think we have come up with a new idea, but really we have retrieved an old idea from memory and failed to attribute the idea to its proper source (Macrae, Bodenhausen, & Calvini, 1999; Figure  7.28). Consider students who take verbatim notes while conducting library research. Sometimes these students experience the illusion that they have composed the sentences themselves. This mistake can later lead to an accusation of plagiarism. (Be especially vigilant about recording the source of verbatim notes while you are taking them.)

George Harrison, the late Beatle, was sued because his 1970 song “My Sweet Lord” is strikingly similar to the song “He’s So Fine,” recorded in 1962 by the Chif- fons. Harrison acknowledged having known “He’s So Fine,” but vigorously denied having plagiarized it. He argued that with a limited number of musical notes avail- able to all musicians, and an even smaller number of chord sequences appropriate

Figure 7.28 Cryptomnesia The 2006 novel How Opal Mehta Got Kissed, Got Wild, and Got a Life turned into a possible case of cryptomnesia. The

author was a student at Harvard University

named Kaavya Viswanathan. Viswanathan

admitted that several passages in the

work were taken from books that she

read in high school. As a result, How Opal Mehta Got Kissed had to be recalled from bookstores. Perhaps Viswanathan, thinking

she had come up with new material, had

retrieved other people’s writing from

memory.

Figure 7.27 Flashbulb Memories Surprising and consequential or emotionally arousing events can produce flashbulb memories.

For example, (a) the Boston Marathon bombings, in 2013; and (b) the attacks on the World Trade Center in 2001.

(a) (b)

264    ■    Chapter 7  MeMory

for rock and roll, some compositional overlap is inevitable. In a controversial verdict, the judge ruled against Harrison.

SUGGeStIBILItY During the early 1970s, a series of important studies con duc- ted by Elizabeth Loftus and colleagues demonstrated that when people are given misleading information, this information affects their memory for an event. In one experiment, a group of participants viewed a videotape of a car—a red Datsun— approaching a stop sign (Loftus, Miller, & Burns, 1978). A second group viewed a videotape of that same scene but with a yield sign instead of a stop sign. Each group was then asked, “Did another car pass the red Datsun while it was stopped at the stop sign?” Some participants in the second group claimed to have seen the red Datsun stop at the stop sign, even though they had seen it approaching a yield sign (Figure 7.29).

In another experiment, Loftus and John Palmer (1974) showed participants a videotape of a car accident. When participants heard the word smashed applied to the tape, they estimated the cars to be traveling faster than when they heard contacted, hit, bumped, or collided. One week later, they were asked if they had seen broken glass on the ground in the video. No glass broke in the video, but nearly one- third of those who heard smashed falsely recalled having seen broken glass. Very few of those who heard hit recalled broken glass. The way that the question was asked apparently influenced their memory for the information. This research reveals the suggestibility of memories in long-term storage.

The suggestibility of memories in long-term storage creates problems for one of the most powerful forms of evidence in our justice system: the eyewitness account. Research has demonstrated that very few jurors are willing to convict an accused individual on the basis of circumstantial evidence alone. But if just one person says, “That’s the one!” then conviction becomes much more likely. This effect occurs even if it is shown that the witness had poor eyesight or some other condi- tion that raises questions about the testimony’s accuracy. The power of eyewitness testimony is troubling because witnesses are so often in error. Gary Wells and his colleagues (1998) studied 40 cases in which DNA evidence indicated that a person had been falsely convicted of a crime. They found that in 36 of these cases, the person had been misidentified by at least one eyewitness (Figure  7.30). Why is eyewitness testimony so prone to error?

First, recall the phenomenon of change blindness. Research on this error showed that a person fails to notice that the person she was talking with has been replaced with a new person (see Scientific Thinking on p. 236). Eyewitness testimony depends critically on paying sufficient attention to an incident when it happens, rather than after it happens. If we are not attending to the information, it won’t be encoded and stored in a way that is accurate. Ultimately, then, the testi- mony is prone to error because often the eyewitness is not paying attention to the right details when the event happens.

FaLSe MeMOrIeS  How easily can people develop false memories? To consider this question, read aloud the following list: sour, candy, sugar, bitter, good, taste, tooth, nice, honey, soda, chocolate, heart, cake, tart, pie. Now put aside your book and write down as many of the words as you remember.

Researchers have devised tests such as this for studying whether people can be misled into recalling or recognizing events that did not happen ( Roediger & McDermott, 1995). For instance, without looking back at the list, answer this question: Which of the following words did you recall—candy, honey, tooth, sweet, pie?

Figure 7.29 Suggestibility In a classic series of studies on

suggestibility, participants viewed a video

showing (a) a stop sign or (b) a yield sign. When later asked whether another car

passed the car at a stop sign, those who

saw the video with a yield sign falsely

reported seeing a stop sign.

HoW Do We ACCeSS oUr MeMorIeS?    ■    265

If you recalled sweet or think you did, you have experienced a false memory, because sweet was not on the original list. All the words on that list are related to sweetness, though. This basic procedure produces false memories reliably. More- over, people are often extremely confident in saying they have seen or heard the words they falsely remember.

Now think back to when you were 5 years old. Do you remember getting lost in a mall and being found by a kind old man who returned you to your family? No? Well, what if your family told you about this incident, including how upset your parents were when they could not find you? According to research by Elizabeth Loftus, you might then remember the incident, even if it did not happen.

In an initial study, a 14-year-old named Chris was told by his older brother Jim, who was part of the study, about the “lost in the mall” incident, in which Chris was lost and then found by an older adult. Jim told Chris the story while they were play- ing a game called “Remember when. . . .” All the other events described by Jim were true. Two days later, when asked if he had ever been lost in a mall, Chris began reporting memories of how he felt during the mall episode. Within two weeks, he reported the following:

I was with you guys for a second and I think I went over to look at the toy store, the Kay- bee toy and uh, we got lost and I was looking around and I thought, “Uh-oh. I’m in trouble now.” You know. And then I . . . I thought I was never going to see my family again. I was really scared you know. And then this old man, I think he was wearing a blue flannel shirt, came up to me. . . . [H]e was kind of old. He was kind of bald on top. . . . [H]e had like a ring of gray hair . . . and he had glasses. (Loftus, 1993, p. 532)

You might wonder if there was something special about Chris that made him susceptible to developing false memories. In a later study, however, Loftus and her colleagues used the same method to see whether they could create false memories in 24 participants. Seven of the participants falsely remembered events that had been told to them by family members who were part of the study. How could this be?

When a person imagines an event happening, he or she forms a mental image of the event. The person might later confuse that mental image with a real memory. Essentially, the person has a problem figuring out the source of the image. To Chris, the memory of being lost in the mall became as real as other events in childhood.

Children are especially likely to develop false memories. The take-home message is that although most times our memory system works well, there are occasions when our memories can be distorted or flat-out wrong.

Figure 7.30 eyewitness accounts Can Be  Unreliable William Jackson (top) served five years in prison because he was wrongly convicted

of a crime based on the testimony of two

eyewitnesses. Note the similarities and

differences between Jackson and the real perpetrator (bottom).

■ retrieval cues help us access information in long-term storage by providing

information about the context in which the information was encoded.

■ Forgetting—due to interference, blocking, or absentmindedness—makes us

unable to access information from long-term storage.

■ Persistence is the recurrence of unwanted memories. It is common among

individuals with posttraumatic stress disorder.

■ Memories can become distorted through memory bias, flashbulb memories,

misattribution, suggestibility, and false memories.

7.4  CheCKpOINt:  How Do We Access Our Memories?

266    ■    Chapter 7  MeMory

BIG QUESTION LEARNING GOALS

a. remember the key terms about memory and encoding.

b. Analyze the three phases of information processing in acquisition of a memory.

c. Understand how attention affects memory.

d. Apply filter theory to your ability to selectively attend to important information.

a. remember the key terms about long-term storage systems and brain processes.

b. Apply the two forms of explicit memory to your life and explain whether they are affected by retrograde amnesia.

c. Understand implicit memory and whether anterograde amnesia affects it.

d. Understand how the brain processes memories.

a. remember the key terms about storage of memories.

b. Understand sensory storage.

c. Understand the relationship between short-term storage and working memory.

d. Apply encoding processes in long-term storage to your life.

e. Understand how information is organized in long-term storage based on semantic meaning.

a. remember the key terms about how we access memories from long-term storage.

b. Understand how retrieval cues improve access to memories in long-term storage.

c. Apply forgetting to your own long-term storage of memories.

d. Understand how memories in long-term storage can become distorted.

7.1 How Do We Acquire

Memories?

7.2 How Do We Maintain

Memories Over

Time?

7.3 What Are Our Different

Long-Term Storage

Systems?

7.4 How Do We Access

Our Memories?

B IG

P IC

T U

R E

KEY TERMS CHECKPOINT

■ Memories are created by encoding information from sensory input. encoded information is maintained in storage. retrieval allows accessing of previously encoded and stored information.

■ Visual attention can be focused on encoding one feature of an object more quickly and effortlessly than two or more features.

■ It is difficult to focus auditory attention on encoding more than one message at a time, and most unattended auditory information is not processed.

■ Selective attention filters out irrelevant information and causes people not to notice large changes in the environment.

memory encoding storage retrieval attention change blindness

■ Amnesia is a deficit in long-term storage. retrograde amnesia is the inability to recall past memories. Anterograde amnesia is the inability to form new memories.

■ explicit memories that we consciously remember include personal events (episodic memory) and general, factual knowledge (semantic memory).

■ Implicit memories are processed without conscious effort and include classical conditioning and procedural memories of motor skills.

■ Prospective memory is remembering to do something in the future, and it has “costs” in terms of reducing attentional resources and impairing short-term storage and working memory processing.

■ Multiple brain regions process memory information. Through consolidation, immediate memories become lasting memories. Memories may be altered through reconsolidation.

retrograde amnesia anterograde amnesia explicit memory episodic memory semantic memory implicit memory procedural memory prospective memory consolidation

■ A huge amount of visual, auditory, taste, smell, and touch information is maintained in sensory storage for up to a few seconds to ensure continuous sensory experiences.

■ Short-term storage keeps about 8 items available for current use for up to 20 seconds. Active processing in working memory increases both this capacity and this duration.

■ Long-term storage of memories is relatively permanent and virtually limitless for deeply encoded information.

■ Information in long-term storage is organized based on meaning through schemas and association networks.

sensory storage short-term storage working memory chunking long-term storage maintenance rehearsal elaborative rehearsal

■ retrieval cues help us access information in long-term storage by providing information about the context in which the information was encoded.

■ Forgetting—due to interference, blocking, or absentmindedness— makes us unable to access information from long-term storage.

■ Persistence is the recurrence of unwanted memories. It is common among individuals with posttraumatic stress disorder.

■ Memories can become distorted through memory bias, flashbulb memories, misattribution, suggestibility, and false memories.

retrieval cue forgetting retroactive interference proactive interference persistence distortion

BIG PICTUre    ■    267

For a self-quiz on this chapter, go to the back of the book and find Appendix B: Quizzes.

268    ■    Chapter 8  Thinking and inTelligence

Big QUeSTiOnS 8.1 What Is Thinking?

8.2   How Do We Make Decisions and Solve Problems?

8.3   What Is Intelligence?

8.4 How Do We Measure Intelligence?

8 IN  2014,  3-Year-OLD  aLeXIS  MartIN, from arizona, did something

unusual. She was accepted to Mensa, the international society for people

with extremely high intelligence (Figure 8.1a). her parents reported that at

1 year of age, alexis had often recited the bedtime story from the night

before word for word. When her father would try to pitch in, she would

correct him. if he said, “Oh, yeah, and then the elephant was the one that

was sharing,” she would say, “no, dad, it was the kangaroo that was shar-

ing” (kaBc-TV, 2014). By age 2, alexis could read and had taught herself

Spanish using her parents’ iPad. “anytime she learns a word,” her father

explained, “and just picks it up through anything, she never ever uses it in

the incorrect context” (Schwartz, 2014). how was a child able to become

so smart in only three years?

Thinking and Intelligence

    ■    269269

270    ■    Chapter 8  Thinking and inTelligence

now consider Phiona Mutesi, a young girl

who grew up in very different circumstances

(Figure  8.1b). Phiona was raised in an

extremely poor neighborhood in kampala,

the capital of Uganda. in 2005, unable to

read or write, sleeping on the streets, and

desperate for food, the 9-year-old Phiona

traveled with her brother to meet a mission-

ary who promised a bowl of porridge to any

child who would try chess. Phiona developed a love for the game. She also

discovered that she was very good at it. indeed, at age 15 Phiona became her

country’s chess champion, and the youngest african chess champion ever

(crothers, 2012). chess requires reasoning about possible moves, solving tacti-

cal problems, and making good decisions. how was Phiona, a child with no

education, able to think so skillfully and become a master at this difficult game?

Because alexis is thought to be highly intelligent, and Phiona shows excel-

lent thinking skills, you might get the idea that intelligence and thinking are

two different things. But actually they are connected, because a person’s

ability to show intelligence is linked to having excellent thinking skills. The

important point is that we can all improve our thinking. Thinking helps us act

intelligently. and by acting intelligently, we can improve our personal lives,

our academic work, and our professional careers. in this chapter, we explore

aspects of thinking, such as decision making and problem solving. We also

explore how thinking relates to intelligence.

Figure 8.1 extraordinary Intelligence and   thinking (a) at age 3, alexis Martin was accepted to Mensa, the international society for people

with extremely high intelligence. (b) at age 15, Phiona Mutesi (front left) used her excellent thinking skills in reasoning, solving

problems, and decision making to become

the youngest african chess champion ever.

8.1 What Is Thinking ?

The chapter opener described Phiona Mutesi’s extraordinary thinking skills in playing chess. But thinking does not have to be extraordinary—we are thinking throughout our daily lives. In fact, you are thinking right now. Are you thinking about Phiona’s skills, the game of chess, or how she has risen above the circum- stance she was born in? This chapter considers the nature of thought: how we represent ideas in our minds, and how we use these ideas to solve problems and make decisions.

LearNINg gOaLS    reaDINg aCtIvItIeS

a. Remember the key terms about representations used in

thinking.

list all of the boldface words and write down their

definitions.

b. apply analogical and symbolic representations to your

life.

Provide one example each of analogical and symbolic

representations that you have used.

c. Understand how concepts are organized according to

the two models of thinking.

Summarize in your own words how each of the two models

of thinking would organize the concept “bird.”

d. apply schemas and stereotypes to your life. Use the idea of schemas to explain a positive or negative

stereotype that you have.

(b)(a)

WhaT iS Thinking?    ■    271

Thinking Is the Manipulation of Mental Representations Representations of the external world are all around us. For example, a road map represents streets. A menu represents food options. A photograph represents a particular part of the world.

As we saw in Chapter 5, representations are created when sensory input is changed into signals the brain can process. When we look at a chair, for instance, our eyes transduce the light into signals, and the brain processes the signals into an image that we call “chair.” In other words, patterns of brain activity provide meaningful information about objects we encounter in our environ- ments. thinking is the mental manipulation of these representations.

Cognitive psychologists study thought and the understanding that results from thinking. For these scientists, the challenge is to understand the nature of our inter- nal, mental representations of information around us. For example, when are the internal representations in our minds like maps or pictures? And when are they more abstract, like language?

aNaLOgICaL aND SYMBOLIC repreSeNtatIONS  When we think about information, we use two basic types of internal representations: analogical and symbolic.

analogical  representations usually correspond to images. They have some characteristics of actual objects. Therefore, they are analogous to actual objects. For example, maps correspond to geographical layouts. Family trees depict branch- ing relationships between relatives. A clock corresponds directly to the passage of time. Figure  8.2a is a drawing of a violin from a particular perspective. This drawing is an analogical representation.

In our mind’s eye, we often form images without trying. For example, think about a lemon. Did your “lemon” thought take the form of an image that resembled an actual lemon? Did you see the lemon’s yellow, waxy, dimpled skin? Did your mouth water (a different sort of mental image)?

Of course, no “picture” exists inside your head. And the mental image is not perfectly accurate. Instead, it generally matches the physical object it repre- sents. By using mental images, you can answer questions about objects that are not in your presence. For example, what color is a lemon? Manipulating mental images also allows you to think about your environment in novel and creative ways. Novel and creative thinking can help you solve problems.

By contrast, symbolic  representations are abstract. These representations usually consist of words or ideas. They do not have relationships to physical quali- ties of objects in the world. The word hamburger is a symbolic representation that usually represents a cooked patty of beef served on a bun. The word violin stands for a musical instrument (Figure  8.2b). There are no correspondences between what a violin looks like, what it sounds like, and the letters or sounds that make up the word violin. The individual characters that make up the word stand for what a violin is, but the letters are arbitrary. You cannot “see” any part of a violin in the shape of the letters v-i-o-l-i-n.

Together, both analogical and symbolic representations form the basis of human thought, intelligence, and the ability to solve the complex problems of everyday life or of special challenges. For instance, recall Phiona from the chapter opener. Like most expert chess players, Phiona probably has rich images in her mind of where the pieces will be on the chessboard many moves in the future (analogical representations). What’s more, she likely uses information about specific chess

thinking The mental manipulation of

representations of information we

encounter in our environments.

analogical representations Mental representations that have some of

the physical characteristics of objects.

symbolic representations abstract mental representations that

consist of words or ideas.

Figure 8.2 analogical versus Symbolic   representations (a) analogical representations, such as this picture of a violin, have some

characteristics of the objects they

represent. (b) Symbolic representations, such as the word violin, are abstract and do not have relationships to the physical

qualities of objects.

Violin (a) (b)

272    ■    Chapter 8  Thinking and inTelligence

strategies that she has read about (symbolic representations). Taken together, Phiona’s rich and accurate mental representations and her ability to manipulate them skillfully are a large part of her success in chess.

MeNtaL MapS Most of us can pull up a visual image of Africa’s contours even if we have never seen the actual contours with our own eyes. Such mental maps include a combination of analogical and symbolic representations. But how accu- rate are our mental maps?

Consider this question: Which is farther east, San Diego, California, or Reno, Nevada? If you are like most Americans, you answered that Reno is farther east than San Diego. But, as you can see from the map in Figure 8.3, the reverse is true. Even if you formed an analogical representation of a map of the western United States, your symbolic knowledge probably told you that a city on the Pacific Coast is farther west than a city in a state that does not border the Pacific Ocean. In this case, a symbolic representation yielded a wrong answer.

Mental maps can sometimes lead to errors because we can represent only a limited range of knowledge. Although our general knowledge is correct, it does not take into account the way Nevada extends to the west and the Pacific Coast near Mexico slants to the east. Regularizing irregular shapes is a shortcut we use uncon- sciously for organizing and representing information in memory. Such shortcuts are generally useful, but they can lead to errors.

Thinking Depends on Categorization of Concepts Much of our thinking, such as the idea of where San Diego and Reno are, reflects visual and verbal representations of objects in the world. It also reflects what you

know about the world. Say that you are shown a drawing of a small yellow object and asked to identify it. Your brain forms a mental image (analogical representation) of a lemon and provides you with the word lemon (symbolic representation). So far, so good.

But picturing a lemon and knowing its name do not tell you what you can do with a lemon. You also know that certain parts of a lemon are edible and that lemon juice usually tastes strong and sour. This additional information helps you know that you can make lemonade by diluting the juice with water and adding sugar. In short, what you know about a lemon and how you think about it influence what you do with a lemon. How do we organize representations of objects so that we can think about them—and interact with them—effectively and efficiently?

SCheMaS aND the CategOrIZatION OF CONCeptS Recall from Chapter 7 that our long-term memories are organized based on schemas. Schemas are our prior knowledge and experience with information. Schemas are also related to the organization of analogi- cal and symbolic representations in our minds. To understand the

relationship between schemas and representations, consider two musical situa- tions: a country music dance (Figure 8.4a) and a symphony orchestra performance (Figure 8.4b).

First, schemas are useful because many of the most commonly encountered situations have consistent attributes. For example, you might expect to see guitars

Figure 8.3 Mental Maps Can Be Inaccurate in our mental maps, we cannot represent

all analogical and symbolic information

with perfect accuracy. as a result, our

mental maps sometimes lead us to

incorrect thinking. For example, San diego

is actually farther east than Reno.

OREGON IDAHO

WASHINGTON

CALIFORNIA

San Diego

Reno

NEVADA

UTAH

ARIZONA

MONTANA

120° 115°

W

N

S

E

WhaT iS Thinking?    ■    273

and fiddles at a country music dance, but you probably don’t expect to see them in an orchestral concert. There, you would expect to see violins and trumpets instead. Second, schemas are useful because people have specific roles within the context of a situation. Your country music schema would include people danc- ing, but your orchestral schema would not include dancing. Finally, schemas are useful because they allow us to think efficiently about objects by categorizing them.

When we use a schema to group things based on shared properties, we create a category about the information. For example, based on the schema for Types of Music, we can create these two categories: Country Music Instruments and Orchestral Music Instruments (Figure  8.5a). Some instruments might exist in just one category or the other (the guitar is used in country bands, and the trumpet is used in orchestras). However, other instruments belong in both categories. For example, the violin, which is used in orchestras, is the same thing as a fiddle, which is used in country music.

Besides creating a category with several things together, we also create a concept to store unique knowledge about each specific member of a category (Figure 8.5b). For example, our concept of a guitar includes the knowledge that it “usually has six strings and is played by plucking.” Our concept of a trumpet is based on knowing that “it is made of brass tubing and it is played by blow- ing into it.” A concept can include knowledge about a relation between items (such as “violins are smaller than guitars” or “watermelons are heavier than lemons”). Or it can consist of information about certain dimensions of each item (such as pitch or sweetness).

In sum, then, we use a common theme to group information by categorizing concepts together based on their similarities and differences. The common theme is a schema. This grouping method is a very efficient way to organize information in our minds, because it ensures that we do not have to store every instance of an object, relationship, or dimension individually. Instead, we store concepts based on the properties shared by certain items, or particular ideas. As described in table  8.1, two models explain how concepts are organized into categories to allow us to think about objects.

Figure 8.4 Schemas about types of Music events Our experiences with music create

memories that are organized into schemas.

(a) Because of our schemas about country music concerts, we expect to see guitars

and fiddles and people dancing.

(b) Because of our schemas about orchestral music concerts, we expect to

see violins and trumpets and people sitting

still while listening.

(a)