The Wiki Man

Are IQ tests really the best way to measure nature vs nurture?

16 March 2019

9:00 AM

16 March 2019

9:00 AM

I have a dim memory from 1970 of a primly dressed distant relative visiting in a Baby Austin. This, I later learned, was the anthropologist Beatrice Blackwood. I googled her 45 years later and was astonished to find she had spent several years in the 1920s and 1930s living alone among Stone Age tribes in New Guinea. Her pet kitten so enchanted the normally fierce Kukukuku that they even built her a temporary house. Aside from her travels, what also surprised me was how close-knit the world of anthropology then was. Just a few hundred people gave rise to debates which are still alive today. Nature vs nurture, for instance. Or IQ testing.

Blackwood was a close friend of Hortense Powdermaker, who was later to write a fascinating study of Hollywood called Hollywood, the Dream Factory. She and Powdermaker shared an intense dislike of Margaret Mead, whose Coming of Age in Samoa depicted a kind of paradise of guilt-free casual sex among Samoan teens, implying sexual mores were merely social constructs. (Mead was later accused of making a lot of it up.)

Blackwood’s other interest was psychometrics — the measuring of mental capacity. She worked at Princeton with Carl Brigham and Clark Wissler, the former having created the Scholastic Aptitude Test (or SAT). Both were avid eugenicists at the time. My relative remained sceptical, even when sent to New Mexico to compare the IQs of Pueblo Indians and Mexicans, something you probably wouldn’t get a grant for today.

Remarkably, almost 100 years later, academia is still divided on these subjects as if on political lines. People who believe in ‘the blank slate’ are sceptical about IQ testing; people who believe in heredity generally support it. Both sides thus hold one moderate opinion and one extreme one.

Those who think that some mental characteristics are inherited are routinely portrayed as extremists. This is silly. Not a single expert considers environment irrelevant; they simply believe people are born with certain inherited mental differences. This is hardly an extreme view: I suspect it is shared by everyone outside academia with more than one child. No, the extremist view is to believe that we are born tabula rasa — the product of our environment and nothing else.

On the other hand, suggesting that one number can be used to gauge mental ability across a wide range of domains does seem pretty extreme to me. Perhaps people who believe in heredity fetishise psychometrics because it supports their case.

But is IQ alone all that predictive? Recently, to my surprise, Nassim Nicholas Taleb attacked the concept on statistical grounds. He argues that while IQ appears to correlate with life outcomes, it only works backwards. Very low IQ can predict very poor outcomes, as you would expect. But above that point IQ predicts very little.

This debate matters. Because if we assume human mental ability is monolithic and it isn’t, the costs of our misconception are very high. We will find ourselves wasting a huge amount of broader talent, while selecting for a narrow proxy skill which does not translate well into practical value — as if you were to select premiership footballers on their ability to play cricket. (That proxy, like IQ, might also work only in reverse — someone who is truly appalling at cricket would rarely be good at football.)

If the education system selects too narrowly, we pay twice. First, because a large number of more widely talented people are overlooked. And secondly, because we risk ending up with a homogeneous caste of technocrats who can think only one way.

An intelligent man can memorise the tube map. A wise one knows when to take a cab.

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