"g" whizzes

Intelligence can be a hot topic. It burst into roaring flames with the publication of The Bell Curve, and the flames haven't died down yet.

As long as I'm looking at the Wilson Quarterly, here's an article from Summer, 2004.

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. ... 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.

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One way of dealing with the problem of inequality is to deny it. There are any number of people who assert that IQ, or "g", the general intelligence factor, either has no real meaning, or doesn't exist. Stephen Jay Gould dismissed it as an artifact of the mathematics used to arrive at the factor.

For something that doesn't exist, "g" is surprisingly robust.

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.

As for multiple intelligences,

However much we might wish that there were many distinct forms of mental ability, a century of research has found none as widely useful as g. Neither of the two major multiple intelligence theorists, Howard Gardner and Yale University’s Robert Stern­­berg, disputes the existence of g, only its preeminence among mental abilities. There are, to be sure, many different human mental abilities, but they are neither independent of one another nor equally useful.

Just to add insult to injury for the egalitarians, a substantial fraction of intelligence is hereditary.

Genes probably work their influence by shaping various metabolic, electrical, and structural features of the brain. For example, the brains of people with higher IQs tend to have a relatively lower rate of energy use (as measured by glucose metabolism) while solving problems, and quicker and more complex brain waves in response to simple perceptual stimuli such as lights and sounds. Researchers have long debated whether people with higher IQs have bigger brains, and the latest findings, based on studies with new brain-scan technology, show that they do. Distinctions in g, or general intelligence, are evidently as much a fact of nature as differences in height, blood pressure, and the like.

(And Jerry Pournelle has a report on his web page discussing the possibility that some genetic diseases are the result of similar effects – effects that tend to "overclock" the brain.)

So how does IQ, "g", or intelligence matter? As David Friedman points out in his book, Hidden Order: The economics of everyday life, the alternative to correct theory is not a blank slate, it's an incorrect theory. A correct theory is one that gives you accurate predictions from the vacts you feed in, and an incorrect theory is one that gives you inaccurate predictions.

If you are using a flawed theory of intelligence to design your curriculum, you will get bad results from that curriculum.

...“adaptive instruction” is regularly attacked as discriminatory because it means treating students differently. Its critics would rather give all students “access” to the “high-status” curricula and self-directed, “constructivist” learning activities that benefit bright students. But that path is far more likely to harm than to help these students, robbing them of the motivation to learn, depriving them of their full potential, and hampering their prospects in a world that increasingly requires (and rewards) well-educated people. Depriving faster learners of curricula that allow them to make the most of their abilities is likewise an injustice to them and to the society that stands to benefit from their eventual contributions. By denying the difficulties in accommodating intellectual difference, multiple intelligence theories may do little more than squander scarce learning time and significant opportunities for improvements in the quality of American schooling.