Getting Smarter About IQ
Intelligence and How to Get It: Why Schools and Cultures Count by Richard E. Nisbett, W.W. Norton, 304 pages, $26.95
All hell broke loose 40 years ago when Arthur Jensen's 120-page article, "How Much Can We Boost I.Q. and Scholastic Achievement?", appeared in the Harvard Educational Review. Critics accused Jensen of racism and worse; noisy protests erupted at Berkeley, where Jensen taught. The flash point was race. Jensen contended that immutable, genetic differences accounted for much of the IQ gap between blacks and whites. And this genetic basis, he argued, spelled failure for Head Start, a program meant to close the gap.
Liberal dissents notwithstanding, Jensen's "genetics is destiny" position had legs. A quarter-century later, Richard J. Herrnstein and Charles Murray recycled the same arguments in The Bell Curve, which sold more than half a million copies in hardcover, an astounding figure for a densely written tome running nearly 1,000 pages. Their central claim was that genetically determined differences in IQ, rather than advantages of wealth or education, largely explained the American social class structure and racial divide. Since intelligence is largely inherited, Herrnstein and Murray argued, social inequalities don't reflect prejudice; rather, they reveal meritocracy at work in the triumph of a "cognitive elite." Here was seemingly reputable social science providing a respectable rationale for ending social welfare.
Although there have been many responses to Herrnstein and Murray, Richard Nisbett's new book, Intelligence and How to Get It, advances the discussion. Synthesizing a wide array of research from neuroscience, psychology, education, and post-Jensen-era genetics, Nisbett shows why the key claims of the hereditarian camp are wrong -- why intelligence isn't fixed at birth and why racial differences in IQ and educational achievement aren't rooted in genetics. And he analyzes the various means by which intelligence can be acquired.
Nisbett marshals supporting evidence for his case from all corners of the scientific universe. Consider the Flynn Effect -- the remarkable fact that each generation scores as much as 25 points higher on IQ tests than the preceding generation -- which can only be explained by changes in the environment. Harvard sociologist Robert Sampson has shown that growing up in a dysfunctional neighborhood reduces a black child's IQ by about 4 points -- the equivalent of a year of school. Quantitative geneticists have demonstrated that raising a child in a well-off rather than a poor family can make as much as a 25-point difference in IQ -- a "truly massive effect," as Nisbett notes -- and that, for poor children, environmental factors explain almost all the observed variations in IQ. Biological geneticists have found that genes trigger environmental influences; what's more, environmental differences determine gene expression. In place of the "nature versus nurture" model, scientists now see nature as being reshaped through nurture and nurture through nature. Just as second-generation Asian Americans are several inches taller than their parents because of better diet, IQ can improve with better schooling and medical care. Theoretically, the sky's the limit: "The degree of heritability of IQ places no constraint on the degree of modifiability that is possible."
The evidence is similarly overwhelming that social circumstances explain racial differences in IQ and educational achievement. In recording low IQ scores and poor school performance, blacks in the United States resemble other stigmatized minorities such as Catholics in Northern Ireland and Sephardic Jews in Israel -- take those groups out of the societies where they are regarded as inferior, and they do better. Black females are twice as likely to have IQ scores above 120 as black males, a finding for which there is no possible genetic explanation (the opposite is true for whites; males are overrepresented at both the higher and lower end of the IQ curve). Or consider this: When U.S. soldiers occupied Germany during and after World War II, black as well as white GIs fathered children with German women. The IQs of the two groups of children were essentially the same -- a particularly remarkable finding since these mixed-race youngsters were likely the targets of prejudice in postwar German society.
How, then, can intelligence be acquired? Intelligence and How to Get It analyzes an array of interventions -- ranging from eye exams to smaller classes, wealth transfers to reductions in maternal stress -- that reduce the race- and class-achievement gaps. For Nisbett the issue isn't whether to intervene, as The Bell Curve would have it, but rather how to intervene most effectively. Because Intelligence and How to Get It assesses many of the policy options, it's a good starting point for a discussion of which strategies get the biggest bang for the buck.
Nisbett explores promising pedagogical approaches for improving the academic performance of minority students, among them student-helping-student "cooperative learning" and a new generation of computer-driven instruction. He describes inexpensive interventions that address what psychologist Claude Steele calls "stereotype vulnerability" -- the anxiety, especially strong among African American youth, about being seen as intellectually inferior, which renders them less likely to succeed in school. Showing black students that intelligence is malleable -- even without telling them anything about themselves -- can improve their academic performance. For instance, when minority high school students were introduced to neuroscience and taught how the brain, rather than being fixed at birth, develops throughout life, their overall grades improved.
Intervening early in children's lives before they set foot in kindergarten can work small miracles. Random-assignment studies of iconic programs like Perry Preschool and Abecedarian, which offered top-drawer early education to poor black students, have shown life-long effects, including significantly higher graduation rates and incomes as well as lower crime rates. Even Head Start, which Jensen pronounced a failure, turns out to have a positive effect, and so does high-quality pre-kindergarten.
Schools aren't the only influence on what children learn -- they're not even the biggest influence. Fetal exposure to alcohol, low birth weight, malnutrition, high lead levels, poor health, inadequate medical care, neighborhood instability, and lapses in parenting practices such as not reading and talking to children -- each of these factors makes a significant difference, and invariably, poor children fare worse.
Uncorrected vision problems are a simple example. One-quarter of American children have uncorrected poor eyesight, and the percentage is far higher among low-income kids. In a study of two inner-city New York high schools, more than half of the students failed the vision test. It took the death of a 12-year-old Maryland child from an untreated toothache that progressed to a brain infection for Americans to wake up to the fact that dental health matters -- tooth decay has cost 51 million missed school hours annually -- and that if you're a poor child, good dental care is hard to come by. Add high rates of asthma to the equation, and it's easy to see why many poor kids don't shine in the classroom. Imagine trying to learn while your gums are bleeding, you're having problems breathing, and you can't make out the blackboard.
The legacy of the hereditarians -- the belief, still prevalent in some circles, that the racial and class gaps in IQ and educational achievement are inherited and unchangeable -- has allowed many Americans to rationalize the miserable conditions that many poor children face. There's no excuse for that indifference now. The evidence is in, and if we want to close those gaps, Nisbett's book shows us what we can do.
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