IQ is one of the most studied constructs in all of psychology — but it's also one of the most contested.
IQ is one of the most studied constructs in all of psychology — but it's also one of the most contested. How should we think about it?
Understanding intelligence, genetics, and their interplay with the environment is complex. Are we products of our environments or our genes? A major takeaway from the mid-20th century "Twin Studies" era of behavior genetics — which compared identical and fraternal twins to estimate the role of genetics — was that IQ is highly "heritable." But modern techniques paint a murkier picture.
Dr. Eric Turkheimer has dedicated decades to studying the genetics of complex behavior using empirical, quantitative, and philosophical methods. He joins Many Minds podcast for a conversation on topics including intelligence and its putatively genetic basis, twin studies, and quantitative estimates of heritability.
Listen with the below player.
"IQ is, to say the least, a fraught concept. Psychologists have studied IQ — or g for “general cognitive ability” — maybe more than any other psychological construct. And they’ve learned some interesting things about it. That it’s remarkably stable over the lifespan. That it really is general: people who ace one test of intellectual ability tend to ace others. And that IQs have risen markedly over the last century. At the same time, IQ seems to be met with increasing squeamishness, if not outright disdain, in many circles. It’s often seen as crude, misguided, reductive—maybe a whole lot worse. There’s no question, after all, that IQ has been misused—that it still gets misused—for all kinds of racist, classist, colonialist purposes. As if this wasn’t all thorny enough, the study of IQ is also intimately bound up with the study of genetics. It’s right there in the roiling center of debates about how genes and environment make us who we are. So, yeah, what to make of all this? How should we be thinking about IQ?
My guest today is Dr. Eric Turkheimer. Eric is Professor of Psychology at the University of Virginia. He has studied intelligence and many other complex human traits for decades, and he’s a major figure in the field of “behavior genetics.” Eric also has a new book out — which I highly recommend — titled Understanding the Nature-Nurture Debate. In a field that has sometimes been accused of rampant optimism, Eric is — as you’ll hear — a bit more measured.
In this conversation, Eric and I focus on intelligence and its putatively genetic basis. We talk about why Eric doubts that we are anywhere close to an account of the biology of IQ. We discuss what makes intelligence such a formidable construct in psychology and why essentialist understandings of it are so intuitive. We talk about Francis Galton and the long shadow he’s cast on the study of human behavior. We discuss the classic era of Twin Studies — an era in which researchers started to derive quantitative estimates of the heritability of complex traits. We talk about how the main takeaway from that era was that genes are quite important indeed, and about how more genetic techniques suggest that takeaway may have been a bit simplistic. Along the way, Eric and I touch on spelling ability, child prodigies, the chemical composition of money, the shared quirks of twins reared apart, the Flynn Effect, the Reverse Flynn Effect, birth order, the genetics of height, the problem of missing heritability, whether we should still be using IQ scores, and the role of behavior genetics in the broader social sciences."
View the show notes for links with detailed information.
Learn more about Templeton World Charity Foundation's Diverse Intelligences priority.
Templeton World Charity Foundation's Diverse Intelligences is a multiyear, global effort to understand a world alive with brilliance in many forms. Its mission is to promote open-minded, forward-looking inquiry in animal, human, and machine intelligences. We collaborate with leading experts and emerging scholars from around the globe, developing high-caliber projects that advance our comprehension of the constellation of intelligences.
Many Minds is a project of the Diverse Intelligences Summer Institute (DISI), made possible through a grant from TWCF to the University of California, Los Angeles (UCLA). The Many Minds podcast is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte. Creative support is provided by DISI Directors Erica Cartmill and Jacob Foster. Artwork featured as the podcast badge is by Ben Oldroyd. Transcripts are created by Sarah Dopierala.
Photo credit: Harvard Art Museums/Fogg Museum, Transfer from the Carpenter Center for the Visual Arts, American Professional Photographers Collection https://hvrd.art/o/132686
