The idea that there’s a single scalar value that measures anything like “general intelligence” (“g”), commonly known as “IQ” or “intelligence quotient”, has been pretty much blown out of the water by this comprehensive study by the University of Western Ontario’s Brain and Mind Institute.
Our attempt to answer [the question of how to quantify relative intelligence] dates back more than five years, when Roger [Highfield] encountered work that I had conducted with Adrian [Hampshire] at the Medical Research Council in Cambridge on a reliable way to carry out cognitive tests online so we could monitor rehabilitation after brain injury, the effect of smart drug trials and so on.
Roger wondered if we could use this test to carry out a mass intelligence test. Drawing on earlier data from brain scans, Adrian and I came up with a series of tests which we knew would trigger activity in as much of the brain’s anatomy as possible, combining the fewest tasks to cover the broadest range of cognitive skills.
We expected a few hundred responses. But thanks to articles in The Daily Telegraph, Discovery and New Scientist, 110,000 people took part from every corner of the world. Once I had used statistical methods to analyse more than a million data points on a representative group of around 45,000, I found that when a wide range of cognitive abilities are probed, the variations in performance can only be explained with at least three distinct components: short-term memory; reasoning; and finally, a verbal component.
No one component, or ‘IQ’, explained all the variations revealed by the tests.
To bolster our results, Adrian and I used a $5 million brain scanner, which relies on a technique known as functional magnetic resonance imaging (fMRI), to study 16 participants as they carried out all 12 tests. We found that each of the three different factors identified by the analysis did indeed correspond to a different brain network: these differences in cognitive ability map onto three distinct circuits in the brain.
The results disprove once and for all the idea that a single measure of intelligence, such as ‘IQ’, is enough to capture all of the differences in cognitive ability that we see between people. Instead, several different brain circuits contribute to intelligence, each with its own unique capacity. A person may well be good in one of these areas, but they are just as likely to be bad in the other two.
I look forward to further verification of the results from the fMRIs, but the ginormous sample size for the actual study (110,000?! That’s absurd!) is pretty much exactly what we need to prove that intelligence is not so simple as it has been abstracted in popular culture.
I further look forward to future ‘race realists’ and other such science-abusing motivated reasoners being forced to hang their prejudices on SEVERAL scalar values, instead of just one.