Monday, November 07, 2011

Study: Flynn effect is not caused by hybrid vigor

From Psychological Review:
Mingroni (see record 2007-10421-011) proposed that heterosis or hybrid vigor may be the principal driver of the Flynn effect—the tendency for IQ scores to increase at a rate of approximately 3 points per decade. This model was presented as a resolution to the IQ paradox—the observation that IQ scores have been increasing despite their high adult heritability—on the basis that substantial changes in IQ can only be accounted for by changes in underlying genetic factors. It is here argued that this model is predicated upon a misconception of the Flynn effect, which is most pronounced on the least g-loaded components of cognitive ability tests and is uncorrelated with genetic effects such as inbreeding depression scores (which are correlated with the g loadings of tests). Evidence supportive of the recently proposed life history model of the Flynn effect is presented. In the discussion, other theoretical objections to the heterosis model are also considered. On this basis, it is concluded that the Flynn effect is strongly entwined with developmental status and that heterosis cannot be its principal cause.

3 comments:

Anonymous said...

Is it possible that the Flynn effect is due to the decline in lead loading in the environment?

Overall scores improve because lead affects everyone.

The difference between whites and blacks could be because there was higher lead loading for blacks because they lived in poorer neighborhoods with more car exhaust and more chipped lead paint.

This can be tested by comparing the onset of Flynn effects with the onset of unleaded gas; unleaded gas was introduced at different years in different countries.

Robert Hume

Polynices said...

The Flynn effect has been going on for far longer than the efforts to remove lead from gasoline. Pretty sure that can't be any part of the explanation.

Average Joe said...

The difference between whites and blacks could be because there was higher lead loading for blacks because they lived in poorer neighborhoods with more car exhaust and more chipped lead paint

This doesn't explain why blacks in Africa do so poorly on IQ tests.