Malcolm Gladwell, best known for his books Blink and The Tipping Point, has just published an article in The New Yorker about the Flynn Effect and how it may undermine many of the assumptions that ground the past century of intelligence testing. Named after New Zealander James Flynn, the “effect” shows that IQ test scores have steadily risen worldwide at the rate of about 3 points per decade. The effect is masked, however, by the fact that IQ tests are periodically re-normed (i.e., made more difficult) to keep the average score at 100. If Flynn is right, this means that our grandparents, on average, had IQ scores nearly 20 points (!) below our own. Interestingly, however, the apparent gains aren’t the same across all intelligence domains. Math, verbal skills, and general knowledge rise the least.

The big gains on the WISC [Wechsler Intelligence Scale for Children] are largely in the category known as “similarities,” where you get questions such as “In what way are ‘dogs’ and ‘rabbits’ alike?” Today, we tend to give what, for the purposes of I.Q. tests, is the right answer: dogs and rabbits are both mammals. A nineteenth-century American would have said that “you use dogs to hunt rabbits.”“If the everyday world is your cognitive home, it is not natural to detach abstractions and logic and the hypothetical from their concrete referents,” Flynn writes. Our great-grandparents may have been perfectly intelligent. But they would have done poorly on I.Q. tests because they did not participate in the twentieth century’s great cognitive revolution, in which we learned to sort experience according to a new set of abstract categories. In Flynn’s phrase, we have now had to put on “scientific spectacles,” which enable us to make sense of the WISC questions about similarities.

Gladwell goes on to cite an important cross-cultural study to drive the point home:

The psychologist Michael Cole and some colleagues once gave members of the Kpelle tribe, in Liberia, a version of the WISC similarities test: they took a basket of food, tools, containers, and clothing and asked the tribesmen to sort them into appropriate categories. To the frustration of the researchers, the Kpelle chose functional pairings. They put a potato and a knife together because a knife is used to cut a potato. “A wise man could only do such-and-such,” they explained. Finally, the researchers asked, “How would a fool do it?” The tribesmen immediately re-sorted the items into the “right” categories. It can be argued that taxonomical categories are a developmental improvement—that is, that the Kpelle would be more likely to advance, technologically and scientifically, if they started to see the world that way. But to label them less intelligent than Westerners, on the basis of their performance on that test, is merely to state that they have different cognitive preferences and habits. And if I.Q. varies with habits of mind, which can be adopted or discarded in a generation, what, exactly, is all the fuss about?

You can find the entire article in the December 17 issue of The New Yorker, or here.

You can also find an item about it in Mind Hacks here.