The Neuroscience of Intelligence
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The Neuroscience of Intelligence
This book introduces new and provocative neuroscience research that advances our understanding of intelligence and the brain. Compelling evidence shows that genetics play a more important role than environment as intelligence develops from childhood, and that intelligence test scores correspond strongly to specific features of the brain assessed with neuroimaging. In understandable language, Richard J. Haier explains cutting-edge techniques based on genetics, DNA, and imaging of brain connectivity and function. He dispels common misconceptions – such as the belief that IQ tests are biased or meaningless – and debunks simple interventions alleged to increase intelligence. Readers will learn about the real possibility of dramatically enhancing intelligence based on neuroscience findings and the positive implications this could have for education and social policy. The text also explores potential controversies surrounding neuro-poverty, neuro-social–economic status, and the morality of enhancing intelligence for everyone. Online resources, including additional visuals, animations, questions and links, reinforce the material.
Richard J. Haier earned his PhD from the Johns Hopkins University and is Professor Emeritus at the University of California, Irvine. He pioneered the use of neuroimaging to study intelligence in 1988 and has given invited lectures at meetings sponsored by the National Science Foundation, the National Academy of Sciences, the Defense Advanced Research Projects Agency, the European Molecular Biology Organization, and Cold Spring Harbor Laboratory. In 2013, he created video lectures, The Intelligent Brain, for The Great Courses. In 2016, he served as President of the International Society for Intelligence Research and became Editor-in-Chief of Intelligence.
Cambridge Fundamentals of Neuroscience in Psychology
Developed in response to a growing need to make neuroscience accessible to students and other non-specialist readers, the Cambridge Fundamentals of Neuroscience in Psychology series provides brief introductions to key areas of neuroscience research across major domains of psychology. Written by experts in cognitive, social, affective, developmental, clinical, and applied neuroscience, these books will serve as ideal primers for students and other readers seeking an entry point to the challenging world of neuroscience.
Forthcoming Titles in the Series:
The Neuroscience of Expertise, by Merim Bilalić
The Neuroscience of Adolescence, by Adriana Galván
Cognitive Neuroscience of Memory, by Scott D. Slotnick
The Neuroscience of Aging, by Angela Gutchess
The Neuroscience of Addiction, by Francesca Filbey
The Neuroscience of Intelligence
Richard J. Haier
University of California, Irvine
32 Avenue of the Americas, New York, NY 10013
Cambridge University Press is part of the University of Cambridge.
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www.cambridge.org
Information on this title: www.cambridge.org/9781107089778
© Richard J. Haier 2017
This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.
First published 2017
Printed in the United States of America by Sheridan Books, Inc.
A catalogue record for this publication is available from the British Library.
Library of Congress Cataloguing in Publication Data
Names: Haier, Richard J.
Title: The neuroscience of intelligence / Richard J. Haier,
University of California, Irvine.
Description: New York, NY : Cambridge University Press, 2017. |
Series: Cambridge fundamentals of neuroscience in psychology |
Includes bibliographical references and index.
Identifiers: LCCN 2016026754 | ISBN 9781107089778 (hardback) |
ISBN 9781107461437 (paperback)
Subjects: LCSH: Consciousness. | Neurosciences.
Classification: LCC QP411 .H35 2017 | DDC 612.8/2339–dc23
LC record available at https://lccn.loc.gov/2016026754
ISBN 978-1-107-08977-8 Hardback
ISBN 978-1-107-46143-7 Paperback
Additional resources for this publication are at www.cambridge.org/us/academic/subjects/psychology/cognition/neuroscience-intelligence
Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party Internet websites referred to in this publication and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.
To my family, who changed the orbit of my life, and
To the memory of my father, who died too young, and
To the memory of my mother, who carried on, and
To the memory of my grandparents, who sacrificed for a future they could scarcely imagine.
Advanced Praise
“Forty years of Haier’s research and thinking about the neuroscience of intelligence have been condensed into this captivating book. He consistently gets it right, even with tricky issues like genetics. It is an intelligent and honest book.”
Robert Plomin, Institute of Psychiatry, Professor of Psychology and Neuroscience, King’s College London
“An original, thought-provoking review of modern research on human intelligence from one of its pioneers.”
Aron K. Barbey, Director, Decision Neuroscience Laboratory, Associate Professor in Psychology, Neuroscience, and Bioengineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign
“Deftly presenting the latest insights from genetics and neuroimaging, Haier provides a brilliant exposition of the recent scientific insights into the biology of intelligence. Highly timely, clearly written, certainly a must-read for anyone interested in the neuroscience of intelligence!”
Danielle Posthuma, Professor of Complex Trait Genetics, VU University Amsterdam, The Netherlands
“The trek through the maze of recent work using the modern tools of neuroscience and molecular genetics will whet the appetite of aspiring young researchers. The author’s enthusiasm for the discoveries that lie ahead is infectious. Kudos!”
Thomas J. Bouchard, Jr., Emeritus Professor of Psychology, University of Minnesota
“Richard Haier invites us to a compelling journey across a century of highs and lows of intelligence research, settling old debates and fueling interesting questions for new generations to solve. From cognitive enhancement to models predicting IQ based on brain scans, the quest to define the neurobiological basis of human intelligence has never been more exciting.”
Emiliano Santarnecchi, Berenson-Allen Center for Noninvasive Brain Stimulation, Harvard Medical School
“Loud voices have dismissed and derided the measurement of human intelligence differences, their partial origins in genetics, and their associations with brain structure and function. If they respect data, Haier’s book will quieten them. It’s interesting to think how slim a book with the title ‘The Neuroscience of Intelligence’ would have been not long ago, and how big it will be soon; Haier’s lively book is a fingerpost showing the directions in which this important area is heading.”
Ian J. Deary, Professor of Differential Psychology, University of Edinburgh
“The biology of few psychological differences is as well understood as that of intelligence. Richard Haier pioneered the field of intelligence neuroscience and he is still at its forefro
nt. This book summarizes the impressive state the field has reached, and foreshadows what it might become.”
Lars Penke, Professor of Biological Personality Psychology, Georg August University Göttingen
“It increasingly appears that we are within years, not decades, of understanding intelligence at a molecular level – a scientific advance that will change the world. Richard Haier’s The Neuroscience of Intelligence gives us an overview of the state of knowledge that covers not only his own field, the brain, but also recent developments in genetics, and he does so engagingly and accessibly for the non-specialist. I highly recommend it.”
Charles Murray, WH Brady Scholar, American Enterprise Institute
“This book was overdue: a highly readable and inspiring account of cutting-edge research in neuroscience of human intelligence. Penned by Richard Haier, the eminent founder of this research field, the book is an excellent introduction for beginners and a valuable source of information for experts.”
Dr. Aljoscha Neubauer, University of Graz, Austria, & past president of the International Society for the Study of Individual Differences
“This book is ‘A Personal Voyage through the Neuroscience of Intelligence’. Reading this wonderful volume ‘forces thinking,’ which can be said only about a very small fraction of books. Here the reader will find reasoned confidence on the exciting advances, waiting next door, regarding the neuroscience of intelligence and based on the author’s three basic laws: 1) no story about the brain is simple, 2) no one study is definitive, and 3) it takes many studies and many years to sort things out.”
Roberto Colom, Professor of Differential Psychology, Universidad Autonoma de Madrid
“Richard Haier’s The Neuroscience of Intelligence is an excellent summary of the major progress made in the fields of psychology, genetics and cognitive neuroscience, expanding upon the groundbreaking work of The Bell Curve. He addresses the many misconceptions and myths that surround this important human capacity with a clear summary of the vast body of research now extending into the human brain and genome.”
Rex E. Jung, Department of Neurosurgery, University of New Mexico
Contents
Preface
Acknowledgments
1What We Know About Intelligence From the Weight of StudiesLearning Objectives
Introduction
1.1What is Intelligence? Do You Know It When You See It?
1.2Defining Intelligence for Empirical Research
1.3The Structure of Mental Abilities and the g-Factor
1.4Alternative Models
1.5Focus on the g-Factor
1.6Measuring Intelligence and IQ
1.7Some Other Intelligence Tests
1.8Myth: Intelligence Tests are Biased or Meaningless
1.9The Key Problem for “Measuring” Intelligence
1.10Four Kinds of Predictive Validity for Intelligence Tests
1.11Why Do Myths About Intelligence Definitions and Measurement Persist?
Chapter 1 Summary
Review Questions
Further Reading
2Nature More than Nurture: The Impact of Genetics on IntelligenceLearning Objectives
Introduction
2.1The Evolving View of Genetics
2.2Early Failures to Boost IQ
2.3“Fraud” Fails to Stop Genetic Progress
2.4Quantitative Genetic Findings also Support a Role for Environmental Factors
2.5Molecular Genetics and the Hunt for Intelligence Genes
2.6Seven Recent Noteworthy Studies of Molecular Genetic Progress
Chapter 2 Summary
Review Questions
Further Reading
3Peeking Inside the Living Brain: Neuroimaging Is a Game-changer for Intelligence ResearchLearning Objectives
Introduction
3.1The First PET Studies
3.2Brain Efficiency
3.3Not All Brains Work in the Same Way
3.4What the Early PET Studies Revealed and What They Did Not
3.5The First MRI Studies
3.6Basic Structural MRI Findings
3.7Improved MRI Analyses Yield Consistent and Inconsistent Results
3.8Imaging White Matter Tracts with Two Methods
3.9Functional MRI (fMRI)
3.10The Parieto-frontal Integration Theory (PFIT)
3.11Einstein’s Brain
Chapter 3 Summary
Review Questions
Further Reading
450 Shades of Gray Matter: A Brain Image of Intelligence is Worth a Thousand WordsLearning Objectives
Introduction
4.1Brain Networks and Intelligence
4.2Functional Brain Efficiency – is Seeing Believing?
4.3Predicting IQ From Brain Images
4.4Are “Intelligence” and “Reasoning” Synonyms?
4.5Common Genes for Brain Structure and Intelligence
4.6Brain Imaging and Molecular Genetics
Chapter 4 Summary
Review Questions
Further Reading
5The Holy Grail: Can Neuroscience Boost Intelligence?Learning Objectives
Introduction
5.1Case 1: Mozart and the Brain
5.2Case 2: You Must Remember This, and This, and This …
5.3Case 3: Can Computer Games for Children Raise IQ?
5.4Where are the IQ Pills?
5.5Magnetic Fields, Electric Shocks, and Cold Lasers Target Brain Processes
5.6The Missing Weight of Evidence for Enhancement
Chapter 5 Summary
Review Questions
Further Reading
6As Neuroscience Advances, What’s Next for Intelligence Research?Learning Objectives
Introduction
6.1From Psychometric Testing to Chronometric Testing
6.2Cognitive Neuroscience of Memory and Super-Memory
6.3Bridging Human and Animal Research with New Tools Neuron by Neuron
6.4Bridging Human and Machine Intelligence Circuit by Circuit
6.5Consciousness and Creativity
6.6Neuro-poverty and Neuro-Social–Economic Status (SES): Implications for Public Policy Based on the Neuroscience of Intelligence
6.7Final Thoughts
Chapter 6 Summary
Further Reading
Glossary
References
Index
Preface
Why are some people smarter than others? This book is about what neuroscience tells us about intelligence and the brain. Everyone has a notion about defining intelligence and an opinion about how differences among individuals may contribute to academic success and life achievement. Conflicting and controversial ideas are common about how intelligence develops. You may be surprised to learn that the scientific findings about all these topics are more definitive than you think. The weight of evidence from neuroscience research is rapidly correcting outdated and erroneous beliefs.
I wrote this book for students of psychology and neuroscience, educators, public policy makers, and for anyone else interested in why intelligence matters. On one hand, this account is an introduction to the field that presupposes no special background; on the other hand, it is more in-depth than popularized accounts in the mass/social media. My emphasis is on explaining the science of intelligence in understandable language. The viewpoint that suffuses every chapter is that intelligence is 100% a biological phenomenon, genetic or not, influenced by environment or not, and that the relevant biology takes place in the brain. That is why there is a neuroscience of intelligence to write about.
This book is not neutral, but I believe it is fair. My writing is based on over 40 years of experience doing research on intelligence using mental ability testing and neuroimaging technology. My judgments about the research to include are based on the existing weight of evidence. If the weight of evidence changes for any of the topics covered, I will change my mind, and so should you. No doubt, the way I judge the weight of evidence will not please everyone, but t
hat is exactly why a book like this elicits conversation, potentially opens minds, and with luck, fosters a new insight or two.
Be advised, if you already believe that intelligence is due all or mostly to the environment, new neuroscience facts might be difficult to accept. Denial is a common response when new information conflicts with prior beliefs. The older you are, the more impervious your beliefs may be. Santiago Ramon Cajal (1852–1934), the father of neuroscience, once wrote, “Nothing inspires more reverence and awe in me than an old man who knows how to change his mind” (Cajal, 1924). Students have no excuse.
The challenge of neuroscience is to identify the brain processes necessary for intelligence and discover how they develop. Why is this important? The ultimate purpose of all intelligence research is to enhance intelligence. Finding ways to maximize a person’s use of their intelligence is one goal of education. It is not yet clear from the weight of evidence how neuroscience can help teachers or parents do this. Finding ways to increase intelligence by manipulating brain mechanisms is quite another matter and one where neuroscience has considerable potential. Surely, most people would agree that increasing intelligence is a positive goal for helping people in the lower-than-normal range who often cannot learn basic self-care routines or employment skills. What then is the argument against enhancing intelligence so students can learn more, or adults can enjoy increased probability of greater achievement? If you have a negative reaction to this bold statement of purpose, my hope is that by the end of this book you reconsider.