Should we renorm IQ tests?

The year in which IQ is tested can make the difference between life and death for a death row inmate. It also can determine the eligibility of children for special services, adults' Social Security benefits and recruits' suitability for certain military careers, according to a new study by Cornell University researchers. That's because IQ scores tend to rise 5 to 25 points in a single generation. This so-called "Flynn effect" is corrected by toughening up the test every 15 to 20 years to reset the mean score to 100. A score from a test taken at the end of one cycle can vary widely from a score derived from a test taken at the beginning of the next cycle, when the test is more difficult, says Stephen J. Ceci, professor of human development at Cornell.

In other words, our definitions of intelligence and mental retardation are more relativistic than we would like to think. Yet the law, and various institutional categories, look to IQ scores as if they were fully objective. Here is the full story.

The Flynn effect implies, if you take it literally, that most people were morons as recently as a few generations ago. Just think, "someone who scored among the best 10% a hundred years ago, would nowadays be categorized among the 5% weakest. That means that someone who would be considered bright a century ago, should now be considered a moron!" So much as I believe in the idea of progress, I don't think we can take the numbers at face value. If you are not convinced, try reading David Hume. Here is another survey of hypotheses, and why they fail to explain the data.

We're past the point where nutrition can explain the rise in IQ scores, and more generally the Flynn effect numbers are inconsistent with more general data about the limits on environment for improving IQ scores. The less culturally specific the test, the stronger the Flynn effect appears. Bill Dickens and Flynn offer some interesting evidence on how genes and environment interact.

My favorite hypothesis, which has no hard data to support it, cites "the impact of the visual and spatial demands that accompany a television-laden, video-game-rich world. " In other words, TV helps us do well on IQ tests. This does not explain why the Flynn effect predates 1950, but perhaps the more general increase in world complexity forces our brains to adapt. In earlier times people were "smart enough" for their environments, and still could create brilliant achievements on the frontiers they faced, still they might have been ill-suited to live in modern times.