About intelligence

I noted in a recent post that, by definition, the mean IQ is 100, and that about half the population falls below that level. That is because intelligence, as measured by standard IQ tests, is a normal or “bell shaped” distribution, with a standard deviation of about 15.

I got to thinking about this some more as my third grandchild took her SAT tests. Now college entrance exams like the SAT and the ACT are highly verbal, and highly culturally biased. Nevertheless, they are pretty good predictors of college success because American undergraduate college classes tend to be heavily loaded toward verbal tasks (reading texts and writing papers), and are also highly culturally biased. The politically-correct move in the 1970’s to “correct” these biases in the college entrance exams missed the point completely. It was the colleges that were biased, and the tests were pretty good predictors of college success precisely because they were biased the same way.

But the intelligence question is really a good bit more complex than that. The Grant Study, which followed 268 Harvard men throughout their careers starting in 1938, found among other things that above a certain minimum level of IQ (about one standard deviation above the mean, or IQ of about 115), intelligence didn’t seem to matter much in success. Other studies have shown that people of very high intelligence (IQ of 150 or higher) seem almost always to suffer other problems. And in fact Mensa, a society one can join only if one is in the top 2% of the population in intelligence, includes a lot of people whose only significant accomplishment in the world seems to that they were able to join Mensa.

Human intelligence actually appears to be a highly multi-faceted attribute, and people who are poor at some facets can be brilliant at others. I have a gift for seeing through complex problems to the core issue, but I am hopeless at remembering names and faces. I can recall for decades complex details of a design, but can’t for the life of me memorize foreign language vocabulary and verb forms. My wife is incapable of understanding mechanical designs, but can watch a stranger in a restaurant for a couple of minutes and accurately (ie – it matches what someone who knows the stranger well knows about them) read their personality and even much of their life story.

Of course our society values and rewards some of these facets, and ignores and disparages others. When we were a mechanical society, mechanics who had a “sixth sense” (high intelligence) about machines and how they operated were much in demand and highly paid. Now that we have become more of an electronic and computer society, those of us with the peculiar mental facilities to visualize electronic circuits and computer programs have better job opportunities. Soon enough this advantage will probably pass to those whose peculiar strengths are in understanding biochemistry and shaping biological components.

So although intelligence as measured by standardized IQ tests is an important measure of ability, it is just one measure of a limited number of facets of real intelligence. Success in the “real world” is shaped just as much, if not more, by cultural factors, emotional abilities, social skills, perseverance, work habits, and even luck. So the fact that about half the population falls at or below 100 in IQ doesn’t tell the whole story. There are a lot of people who wouldn’t score especially high in a standard IQ test who are nevertheless highly successful in the real world, and very good, even brilliant, at some non-verbal skills not measured by standard IQ tests. And there are some very high IQ people who are, frankly, thoroughly dysfunctional and complete failures in the real world.