20 October 2011

How Stable Is IQ?

IQ has a significant hereditary component and normally when someone has a major difference in IQ test results a few years apart, which themselves show a basically bell shaped distribution, not biased up or down, up to a bit more than one standard deviation in a sample of 33 people who were aged 14 when they started the study and were tested agains four years later, the change is assumed to be due to the inaccuracy of the test.

But, bolstered by MRI scans, a study announced today suggests that a significant share of the difference is due to real differences in teenaged brain development, rather than merely issues related to the testing instrument itself.

The implication, that education in the teen years really does matter and that nuture factors in one's teens can materially impact one's IQ, makes education seem far less futile than it does when one merely look at averages for larger numbers of people that obscure individual shifts in IQ in the teen years, even if they arise from real brain development.


The Reluctant Apostate said...

The news outlets have certainly touted this as an opening for education to have some effect on intelligence, but I think that it's possible that this could work in the opposite direction. If I recall correctly, previous studies have shown that adult IQ has a greater heritability than childhood IQ. What this teenage IQ fluctuation may be a reflection of is genetic changes that are only expressed around the time of puberty.

Andrew Oh-Willeke said...

Certainly. But, the prevailing view among many scientists prior to this point was that IQ was fixed at a point closer to around age seven barring injury or exposure to toxins like lead.