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Why IQs Rise

IN THE MID-’80s, the political philosopher James Flynn noticed a remarkable but puzzling trend: for the past century, average IQ scores in every industrialized nation have been steadily rising. And not just a little: nearly three points every decade. Every several years, IQ tests test have to be “re-normed” so that the average remains 100. This means that a person who scored 100 a century ago would score 70 today; a person who tested as average a century ago would today be declared mentally retarded.

This bizarre finding—christened the “Flynn effect” by Richard Herrnstein and Charles Murray in The Bell Curve—has since snowballed so much supporting evidence that in 2007 Malcolm Gladwell declared in The New Yorker that “the Flynn effect has moved from theory to fact.” But researchers still cannot agree on why scores are going up. Are we are simply getting better at taking tests? Are the tests themselves a poor measure of intelligence? Or do rising IQ scores really mean we are getting smarter?

In spite of his new book’s title, Flynn does not suggest a simple yes or no to this last question. It turns out that the greatest gains have taken place in subtests that measure abstract reasoning and pattern recognition, while subtests that depend more on previous knowledge show the lowest score increases. This imbalance may not reflect an increase in general intelligence, Flynn argues, but a shift in particular habits of mind. The question is not, why are we getting smarter, but the much less catchy, why are we getting better at abstract reasoning and little else?

Flynn starts from a position that accepts the idea of IQ—a measure that supposedly reflects an underlying “general” intelligence. Some researchers have objected to this concept in part because of its circular definition: psychologists measure general intelligence by analyzing correlation patterns among multiple intelligence tests; someone with greater general intelligence will perform better on all these subtests. But although he does not quibble with the premise, Flynn argues that an increase in general intelligence is not the full story when it comes to the past century’s massive score gains.

If we were really getting smarter overall, scores should be going up across all the subtests, but that is not the case. To understand the score gains, then, we need to set aside issues of general intelligence and instead analyze patterns on the IQ subtests. Doing so opens a window into cognitive trends over time and reveals a far more interesting picture of what may be happening to our minds. This inquiry is at the heart of Flynn’s thirty-year career, and it drives his thoughtful (though occasionally tedious) book.

As Flynn demonstrates, a typical IQ test question on the abstract reasoning “Similarities” subtest might ask “How are dogs and rabbits alike?” While our grandparents were more likely to say something along the lines of “Dogs are used to hunt rabbits,” today we are more likely to say the “correct” answer, “Dogs and rabbits are both mammals.” Our grandparents were more likely to see the world in concrete, utilitarian terms (dogs hunt rabbits), but today we are more likely to think in abstractions (the category of “mammal”). In contrast, the Arithmetic IQ subtest and the Vocabulary IQ subtest—tests that rely on previous knowledge—show hardly any score increase at all.

Why has this happened? The short answer, according to Flynn, is that a convergence of diverse social factors in post-industrial societies—from the emphasis of scientific reasoning in school to the complexity of modern video games—has increasingly demanded abstract thinking. We have begun to see the world, Flynn says, through “scientific spectacles.” To put it even more broadly, the pattern of rising IQ scores does not mean that we are comparing “a worse mind with a better one,” but rather that we are comparing minds that “were adapted to one cognitive environment with those whose minds are adapted to another cognitive environment.” Seen in this light, the Flynn effect does not reflect gains in general intelligence, it reflects a shift to more abstract thinking brought about by a changing social environment. We aren’t getting smarter; we are getting more modern.

This interpretation of rising IQ scores was detailed in 2007 in Flynn’s book, What Is Intelligence? In Are We Getting Smarter? he both summarizes the previous book and explores a wide new range of possible implications. The chapters are organized into broad categories—“Developing nations,” “Youth and age,” “Race and gender”—into which he dumps a whole host of observations and speculations. “Death, memory, and politics,” makes a passionate plea to consider the Flynn effect when considering IQ scores of inmates on death row. No one who scores at or below 70 (the cutoff for mental retardation) can now legally be executed in the United States, but because inmates are often given old or improperly calibrated tests, their scores may not reflect an accurate measure of their IQ, and a few miscalculated points can mean the difference between life and death. And the problem of miscalibrated scores may extend far beyond the justice system: “we are now aware that a whole range of clinical measuring instruments … are also suspect because of obsolete norms.” The growing number of elderly people diagnosed with memory disorders, for example, may be inflated because tests are administered without taking the Flynn effect into account. Flynn’s writing can be a bit rambling and pedantic, and the book feels like more of a sequel than a cohesive new contribution, but woven into the excessive tables of statistics and clunky academic prose are such moments of genuine insight.

Implicit in Flynn’s argument that we are becoming “more modern” is that IQ gains are due to environmental factors, not genetic ones. Some of the most successful moments in this book come when Flynn considers IQ data in combination with sociological facts in order to do away with absolutist notions of intelligence. Given the long and troubled history of intelligence science—e.g., eugenics—this stance is significant. He invokes environmental factors, for example, to explain the shrinking male/female IQ gap and debunk notions of innate differences in intelligence between men and women. (If you do not lump current generations of women with past generations and if you separate university from non-university populations, the enormous male advantage disappears.) He uses similar reasoning to explain IQ differences between developed and developing countries. Many developing countries have seen massive IQ gains in recent years and seem to be closing the IQ gap with more developed countries; those that are aren’t closing the gap, such as Sudan, are lagging behind because of extenuating environmental circumstances that would stifle any group’s IQ scores: natural disasters, disease, hunger. It is also hard for a developing nation to raise overall scores when women do not have access to education. If half your population is uneducated, your country’s IQ scores are going to drag.

The focus on environmental factors is where Flynn’s book gets interesting: in making the case that the Flynn effect is connected to modernity, the book offers a broader indictment of intelligence research and the field of psychology as a whole. Flynn laments the “failure of the sociological imagination”—the tendency in psychology to overlook environmental factors. “Somehow, psychologists have developed the habit of ignoring social scenarios that explain their results,” Flynn writes. “In so far as they attempt to integrate the psychology of human intelligence with another layer of analysis, they choose brain physiology.”  By focusing in on the brain, Flynn argues, we risk missing the forces that shape it. This is not just another nature/nurture argument; it is a call for a complex, interdisciplinary science of the human mind that sees the individual as an open system constantly reacting to and acting upon her environment. It is also a rejection of the bigotry and the elitism implicit in research that claims to locate innate differences between groups and an appeal for the inclusion of another dimension—time—into the calculus of intelligence research. Neither human intelligence nor culture is static. They change over time, and those changes can offer profound insight into how our minds work, and why.

Flynn’s argument that IQ gains open a window into what he has called “the cognitive history of the twentieth century” is persuasive, and his shift away from the “innate” elements of intelligence is welcome. But there is still a value system at work here. He suggests a hierarchy of more-to-less-modern nations: those engaged in tasks of greater “cognitive complexity” are at the fore, and the others are straggling behind. He flatly states that he is “no cultural relativist,” and implies that the developed world “represents a higher stage of civilization,” a world to which “almost all of the nations on this earth aspire.” This is the great paradox of the book: in disassembling one hierarchy, it assembles another.

Despite its flaws, there is a deeper, almost humanitarian, purpose driving Are We Getting Smarter? It urges us—researcher and layperson alike—to take the veiled bigotry of absolute genetic differences among races, genders, and nations off the table. If we can figure out why intelligence measures are different among groups, if we can understand the complex interplay of environmental pressures that affect those measures, then we will be closer to a more nuanced understanding of who we are, where we have been, and where we are going.

Meehan Crist is Resident Writer in Biological Sciences at Columbia University. She is working on a nonfiction book about traumatic brain injury. Tim Requarth is an NIH National Research Service Award Fellow and doctoral candidate in neuroscience at Columbia University. Requarth co-directs and Crist is a founding member of NeuWrite (, a New York-based collaborative writing group of scientists and writers.