The Flynn Effect

Crooked Timber has a post up about the Flynn effect, a subject I've always found interesting. Flynn found massive gains in IQ across time, with average children's performance increasing as much as a standard deviation in one generation. This is a shocking blow to the few remaining people who think that IQ is all about genetics, but it also raises questions about the general relations between IQ and intelligence. Clearly, the argument goes, if intelligence were rising at the rate of one SD per generation, we'd be in the middle of an intellectual Renaissance the likes of which the world has never seen.

I think the Flynn effect can be attributed to a number of things - improved nutrition, more widespread education, the spread of mass communications (there used to be a big rural-urban difference in mean IQ, which has subsequently disappeared within the U.S.), and increased opportunity for people in general to become familiar and comfortable with test-taking situations. Moreover, the kinds of tasks that appear on children's IQ tests have trickled down into the culture. Fifty years ago, a young child taking the Wechsler Intelligence Scale for Children (WISC) might be faced with solving a maze for the first time. Today, you find mazes on the backs of cereal boxes.

I don't think it's coincidental that nonverbal, puzzle-like components of IQ tests have shown much larger Flynn effect gains across time than more academically-rooted components like vocabulary and arithmetic. If the Flynn effect is driven by increased exposure to testlike elements in the general culture, you'd expect to see smaller gains on elements people have been exposed to for a very long time (like arithmetic) and larger gains on elements that have only become commonly encountered in the last generation or so (like complex pattern-matching games).

(As a sidenote: I could practically have written 75% of the Crooked Timber post's comments section without reading it first, just based on prior online arguments. No matter what opinion most people have of IQ, a lot of the things they're sure they know about IQ tests just aren't so... but that's a rant for another time.)