Friday, January 18, 2008

IQ and the Flynn Effect

Back in the 1980s when I worked on the development of the Wechsler Intelligence Scale for Children, Third Edition (WISC-III), I was fascinated with a process commonly referred to at the time as "continuous norming." Applied by Dr. Gale Roid as developed by Professor Richard Gorsuch, continuous norming was a slick way to improve the precision of empirical norms. While things seemed to get in the way of any in-depth analysis of the procedure, and while I did stay in contact with Professor Gorsuch occasionally, I did nothing to understand or apply the process anew and simply moved on.

Over the winter holidays, I was reading The New Yorker (yes, even people who live in Iowa read The New Yorker) and discovered, much to my surprise, a story about IQ written by Malcolm Gladwell, titled "None of the Above: What IQ doesn’t tell you about race" (December 17, 2007, pp. 92-96). As you may recall, Malcolm Gladwell is the author of both The Tipping Point and Blink. Both books interested me, so I read what he had to say about IQ.

Gladwell references something he (and apparently others) call “The Flynn Effect.” The Flynn Effect comes from James Flynn, author of What is Intelligence?, and is essentially the term used to describe what Flynn claims to have discovered—that all humans are getting smarter. As Gladwell points out, Flynn looked at years of IQ assessment data from all over the world and concluded that humans gain three IQ points per decade. Gladwell then tries to put this in context. For example, if Americans' average IQ in 2000 was 100, then in 1990 it was 97, in 1980 it was 94, in 1970 it was 91, and so on. If true, this implies that my grandfather (and yours) were “dull normals” at best, but were most likely mentally retarded. Flynn claims that this is due more to the way we measure intelligence than anything else. He states, as Gladwell points out:

“An IQ, in other words, measures not so much how smart we are as how modern we are.”
For example, when members of the Kepelle tribe in Liberia were asked to associate objects such as a potato and a knife, they linked them together according to function. As Gladwell points out, after all, you use a knife to cut a potato. Most IQ assessments would expect the potato to be linked to other legumes and the knife to be linked to other tools. Flynn claims modern culture has “taught” us to think in the way the IQ assessment measures and, while this is different than how the Kepelle thought, there is no reason to believe that their thinking represents anything less intelligent.

Gladwell then tries to articulate the issue that Flynn makes regarding intelligence test norms. He observes that if the center of each new edition of the WISC is 100, and everyone is getting smarter by three IQ points per decade, than each subsequent form of the WISC (the first WISC was standardized in the 1940s) must be getting harder. Very interesting—I need to dig up references on the “continuing norming” process used for the WISC and see what impact, if any, such a process might have on "The Flynn Effect."

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