August 8, 2006

Is the Black-White IQ gap shrinking?

As I reported in in August 2005, there is some evidence that the black-white IQ gap is finally narrowing:

One of the most newsworthy aspects of "The Inequality Taboo" is [Charles] Murray's view that the white-black IQ gap may have narrowed slightly in recent years. According to Murray's article, the three most recent re-normings of major IQ tests came up with a mean white-black gap of 0.92 standard deviations, or 14 points.

That doesn't sound like much of a change from the one standard deviation (15 points) racial gap that IQ realists have been talking about for decades. But, in reality, they've been intentionally understating the traditional size of the difference. A 2001 meta-analysis of eight decades of data suggested a 1.1 standard deviation gap (16.5) points. So, if this new 14 point gap found in the three recent re-normings holds up as more data comes in, we may have seen some significant progress on this massive social problem.

Currently, though, the evidence remains far from clear. Murray writes in a footnote:

"Forced to make a bet, I would guess that the black-white difference in IQ has dropped by somewhere in the range of .10–.20 standard deviations over the last few decades. I must admit, however, that I am influenced by a gut-level conviction that the radical improvement in the political, legal, and economic environment for blacks in the last half of the 20th century must have had an effect on IQ."

Now, James Flynn (of Flynn Effect fame) and William Dickens have published "Black Americans reduce the racial IQ gap: Evidence from standardized samples" in Psychological Science. Looking at pretty much the same tests as Murray did, such as the military's AFQT, the Wechsler, and the Stanford-Binet, they argue for a 4 to 7 point decline in the gap between 1972 and 2002. (By the way, this would be substantially bigger than increases in interracial marriage, or in mixed race people changing their designation from white to blacks, could account for.)

The results they find are rather curious, however. They come up with strikingly different black IQs (on a scale where non-Hispanic white IQ is 100 and the standard deviation is 15) at different ages:

"95.4 at age 4, 90.5 at age 12, 87.0 at age 18"

In a counter-rebuttal to Arthur Jensen and J.P. Rushton's rebuttal, Flynn and Dickens mention something else pretty interesting:

"Our data give a current IQ for blacks age 24 of 83.4 or exactly 1.1 SDs below whites."

These data could be explained by two contrary models. Blacks could be getting smarter down through history, or blacks could be getting less smart as they age. (Or a combination of the two.) I haven't read the papers closely enough to see how strong the evidence is for one or the other explanation.

A few years ago, Flynn and Dickens put forward a theory that small differences in genetics get magnified by the environment because smart people choose more mentally challenging environments for themselves as they age. Steve Johnson writes:

Imagine "somebody who starts out with a tiny little physiological advantage: He's just a bit taller than his friends," Dickens says. "That person is going to be just a bit better at basketball." Thanks to this minor height advantage, he tends to enjoy pickup basketball games. He goes on to play in high school, where he gets excellent coaching and accumulates more experience and skill. "And that sets up a cycle that could, say, take him all the way to the NBA," Dickens says.

Hopefully, I've managed to convince my friend Flynn to stop using that particular analogy because NBA basketball players don't have a "tiny little physiological advantage" but instead have a huge one -- about 9 to 10 inches in height on average compared to the normal American man. Golf would make a more plausible analogy since the physiological advantages of star golfers aren't readily apparent until they swing. Phil Mickelson, for example, looks more like a guy sitting on his couch watching sports on TV than a TV sports hero.

Similarly, by the Flynn-Dickens logic, it could be that blacks are making themselves dimmer as they get older by listening to gangsta rap and the other anti-intelligent cultural tendencies they've developed.

So, if Flynn and Dickens are serious about altering the environments of blacks enough to put a sizable dent in the white-black IQ gap in adulthood, they would call for a police state that bans all manifestations of hip-hop, that executes Jay-Z and Dr. Dre as bad examples, that puts minor rappers and black celebrities in concentration camps, etc. I doubt if that would work, but it's at least a semiserious proposal for grappling with a problem of this magnitude. But they don't seem to be all that serious about actually doing anything about it.

My published articles are archived at -- Steve Sailer

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