Tuesday, May 06, 2008

7.5 Point Reduction in B-W IQ Gap in the 1900's

None other than hereditarian Charles Murray himself, shows that Blacks reduced the Black-White IQ gap by 7.5 points (or .5 standard deviation) for the cohorts born in the 1920's (my father's generation) to the cohorts born in the 1960's (my three siblings' generation). Since then, Murray claims that the B-W gap has actually increased slightly.

The test used was Woodcock, and the ages were from 6-65. The .5 standard deviation reduction occurred on IQ and the two measures of g, fluid g and crystallized g. Fluid g is roughly a measure of raw brain processing power, and peaks early, possibly in the early 20's, though it seems hard to believe if you spend a lot of time around college kids.

Crystallized g is the sort of thing that 50-year old's like me excel in, and it may be called knowledge, or wisdom, or cumulative life experience. There is a reason why primitive tribes always chose an older person or persons to make all of the important decisions for them, and why they paid so much attention to elders.

This secular rise in IQ and both forms of g can only be seen as a Flynn Effect. The notions that the the B-W IQ gap is genetic and set in stone forever and cannot be moved 1% by any environmental factor, or that the Flynn Effect is not on g, or is not on crystallized g, or whatever the fake hereditarian (usually racist) line is today, or that recent rises are only on certain tests and only affect kids, must all be rejected.

I haven't looked into the study yet, but the whole thing is online at the link if you want to pick it over. The B-W shrinkage may have been due to better nutrition for Blacks or possibly to the increased complexity of American society during this period.

Blacks born during this period also started to see a lot of benefits in the way of employment and education open up for them. The reason for the slight shrinkage in recent years in not known, but other data show that in Black kids anyway, the gap has closed 5-6 points over the past 30 years.

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