By Stuart Ritchie
[su_pullquote align=”right”]Decades of well-replicated research point to IQ tests as some of the most reliable and valid instruments in all of psychological science.[/su_pullquote]
IQ tests just measure how good you are at doing IQ tests. This is the argument that is almost always made when intelligence-testing is mentioned. Its often promoted by people who are, otherwise, highly scientifically literate. You wouldnt catch them arguing that climate change is a myth or that vaccines might cause autism. But saying that IQ tests are useless is just as wrong as these notions: in fact, decades of well-replicated research point to IQ tests as some of the most reliable and valid instruments in all of psychological science.
So what does an IQ test which might consist of, for example, shape-based puzzles, timings of how quickly you can check through lists of meaningless symbols, memory tests, and vocabulary measures actually tell you? The strongest correlation is perhaps unsurprising: an IQ score is highly predictive of how people will do in school. One largestudyfound that IQ scores at age 11 correlated 0.8 (on a scale of -1 to 1) with school grades at age 16. Surely this gives us some basis for calling these measuresintelligence tests. But thats just the beginning: higher IQ scores are predictive of moreoccupational success,higher income, and betterphysical andmental health.
Perhaps the most arresting finding is that IQ scores taken in childhood are predictive of mortality.
Smarter people live longer, and this association is still there after controlling for social class.
Neuroscientists and geneticists have also made good progress in understanding human intelligence. Meta-analyses of hundreds of studies confirm that people with larger brains tend to get higher scores on IQ tests, andresearchon more specific brain regions and features continues apace. We know from studies of twins, and from studies done directly on DNA, that intelligence test scores areheritable: a substantial portion of the intelligence differences between people are due to genetics. Weve already begun to find some of thespecific genesthat might be responsible for these differences, and further findings are on the way.
Neuroscientists have confirmed that people with larger brains tend to perform better in IQ tests | Photo Courtesy: Medialxpress[su_pullquote]Theres nothing in principle to suggest that we cant raise peoples IQ scores, at least to a degree.[/su_pullquote]
People make the mistake of assuming that intelligence is immutable because it has been linked to genetic and neural features, and because it seems highly stable across the lifespan. Ones IQ score, they think, is set in stone, condemning you to a poorer life if its below-average. This is a mistake. Theres nothing in principle to suggest that we cant raise peoples IQ scores, at least to a degree (though many recent attempts to do so have beennon-starters). Indeed, IQ scores have been rising inexorably across the years, in a process called theFlynn Effect, for (non-genetic) reasons that arent yet clear.
Another mistake is to think that anyone has ever claimed that an IQ score sums up a person.
This is another falsehood, since all IQ researchers would readily accept that personality, motivation, and a host of other factors including luck are allcrucialfor success in life.
It would be foolish to deny that there are any skeletons in IQ-testings closet. Many, though by no means all, of the originators of the tests were involved with the eugenics movement in the early 20th century, and its reasonable to be appalled at some of the uses to which IQ tests were originally put. But these concerns are irrelevant to the main question of whether an IQ score, taken today, can tell you anything about a person. Facts are facts, and the validity of intelligence test scores is amply backed by voluminous evidence.
As all the studies linked above show, IQ tests are useful in a wide variety of situations, from education to medicine to the world of work. We need IQ tests to help us understand how the brain ages, and how we can help it age more healthily. We need IQ tests to help us work out how to boost peoples intelligence, and thus to boost their productivity. Perhaps, above all, IQ tests are one of the tools with which psychologists can dissect and examine human intelligence: wed be extremely unwise to continue to ignore their insights.
Stuart Ritchie is a postdoctoral fellow in cognitive ageing at the University of Edinburgh. His research interests include human intelligence differences, genetics, and education.
This article was originally published on Aeon.
Featured Image Credits: Huffington Post
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