Att. Jason Richwine: You're Not the First Guy to (Wrongly) Believe Immigrants are Dumb: The human brain remains, in many crucial aspects, a mystery to science. So what is IQ? It is a measure of the capacity to learn in the linear fashion prized by Western culture, and we know that it is partially determined by genetics. Yet in the life of the average, individual human, those "innate" genes are vastly, vastly overpowered by the effects of environment: decent nutrition; an emotionally stable, vocabulary-rich home life; physically and emotionally attentive parents; good schools and teachers. All those factors are in shorter supply among high-poverty populations. Claiming that such populations are genetically inferior ignores about a century of research and writing on the malleability of IQ and the proper uses of intelligence assessments.
Alfred Binet, the French psychologist who invented IQ testing, made quite clear that his exams could not draw conclusions about the difference in innate ability between two individuals from different cultural and socioeconommic populations. Little has changed. In 1995, after the tempest around Charles Murray's The Bell Curve, Nobel Prize-winning economist James Heckman summarized what is known about intelligence, race, class, and heritability. The consensus is that IQ can help distinguish between the capacities of "within-group" individuals--for example, two upper-middle class American Jewish girls who attended good public schools and then Brown University. However:
IQ supremacists claim IQ is a measure of innate ability, yet IQ tests are actually achievement exams, which can be "manipulated by educational interventions." If a child is asked during an IQ assessment to memorize and repeat a long string of numbers, for example, she will do a better job if she has an excellent math teacher or if her dad helps her with her math homework at night -- if, in other words, she has had the opportunity to gain confidence around numbers.
If two socioeconomically-alike individuals are compared, the person with the higher IQ will often have superior social outcomes. He is more likely to graduate high school or get a high-paying job. Yet the evidence suggests that IQ itself--as opposed to all the other social factors correlated with IQ, like parental income--is responsible for only a small fraction of this difference in achievement. Not to beat a dead horse, or anything, but correlation does not imply causation.
IQ is one predictor of success on the labor market, but it is not the only or even the most important factor. Social skills and work ethic, for example, are not measured by IQ, yet can be substantially improved through education and training, especially if that training is received in childhood.
We know socioeconomic factors influence intelligence, but our measures of those factors are crude. For example, a nutritious diet increases cognitive function, but we don't know by exactly how much. If we get better at isolating and measuring such factors, it might turn out that genetic intelligence is even less important than we assume.
One of the books I recommend most often is The Big Test by Nick Lemann. He shows how wave after wave of new immigrants, including white immigrants, were assumed to be stupid, in part because of their bad scores on IQ exams. This is true even of those groups, like Jews, who we think of as "smart" today. Here Lemann writes about IQ tests given to World War I recruits, and the way they were intepreted by Carl Campbell Brigham, a Princeton psychologist who became an author of the SAT:
On the Army IQ tests, Nordics scored higher than Alpines, who scored higher than Mediterraneans. The test results as a whole were like a photograph of American culture, so faithfully did they reproduce the social order. Officers scored higher than enlisted men, the native-born scored higher than the foreign-born, less recent immigrants scored higher than more recent immigrants, and whites scored higher than Negroes. There were ironclad natural laws at work here, Brigham felt, and he warned that wishful thinkers who pretended otherwise were deluding themselves--writing, for example, "Our fugure, then, would rather tend to disprove the popular belief that the Jew is highly intelligent."
Brigham's stern conclusion was this: "American intelligence is declining, and will proceed with an accelerating rate as the racial admixture becoems more and more extensive…. These are the plain, if somewhat ugly, facts that our study shows.