Schools and the g Factor

In the world of the American public school, few subjects are more controversial than intelligence. If there’s a tension in American society between the ideal of equality and the pursuit of meritocracy, that tension escalates into the equivalent of a migraine headache in the schools. Called upon to produce young people fully prepared for citizenship and ready to meet the competitive challenges of the modern economy, the schools are also seen, at the same time, as the nation’s last best hope to level the playing field and ensure equal opportunity for all. In no American institution is the egalitarian strain of the American creed stronger. And the very notion that school performance is strongly influenced by general intelligence—a quality partly inborn—seems to contradict this deeply held ideal of equality. During the past few decades, the word intelligence has been attached to an increasing number of different forms of competence and accomplishment—emotional intelligence, football intelligence, and so on. Researchers in the field, however, have largely abandoned the term, together with their old debates over what sorts of abilities should and should not be classified as part of intelligence. Helped by the advent of new technologies for researching the brain, they have increasingly turned their attention to a century-old concept of a single overarching mental power. They call it simply g, which is short for the general mental ability factor. The g factor is a universal and reliably measured distinction among humans in their ability to learn, reason, and solve problems. It corresponds to what most people mean when they describe some individuals as smarter than others, and it’s well measured by IQ (intelligence quotient) tests, which assess high-level mental skills such as the ability to draw inferences, see similarities and differences, and process complex information of virtually any kind. Understanding g’s biological basis in the brain is the new frontier in intelligence research today. The g factor was discovered by the first mental testers, who found that people who scored well on one type of mental test tended to score well on all of them. Regardless of their contents (words, numbers, pictures, shapes), how they are administered (individually or in groups; orally, in writing, or pantomimed), or what they’re intended to measure (vocabulary, mathematical reasoning, spatial ability), all mental tests measure mostly the same thing. This common factor, g, can be distilled from scores on any broad set of cognitive tests, and it takes the same form among individuals of every age, race, sex, and nation yet studied. In other words, the g factor exists independently of schooling, paper-and-pencil tests, and culture. Though there has been intense controversy about IQ tests over the years, psychologists continue to see them as valid and useful gauges of student potential.