This article first appeared in issue 16 of our free digital magazine CURIOUS.
In the public imagination, IQ is often considered the gold standard for measuring intelligence – an ironclad, bulletproof measure of a person’s brain power. However, not everyone is completely convinced of the promise it offers.
Some argue that this risks being limiting and unable to take into account the rich diversity of the human mind. Conversations about IQ can also tend to radiate the stench of pseudoscientific BS. At worst, IQ scores can be (and have been) weaponized by racist ideologies to spread hatred and discrimination. Do IQ scores have any value at all?
What actually is an IQ score?
IQ tests have changed the world, but they have humble beginnings. Their origins can be loosely traced back to 1905, when psychologists Alfred Binet and Théodore Simon designed a test to see which schoolchildren in France needed extra help with their studies.
Children were assessed on their performance in three key skills – verbal reasoning, working memory and visuospatial skills – compared to others their age, with their skills reduced to a number.
This became the basis of modern intelligence tests, although the term IQ – which stands for intelligence quotient – was not coined until 1912 by William Stern, a German psychologist and philosopher.
Modern IQ tests still work on a similar principle to the exams given to French children almost 120 years ago. People are assessed on a set of cognitive skills – verbal reasoning, working memory and visuospatial skills – and their performance is compared to a representative sample of the population.
The average IQ score is set at 100, which means that about half of the people tested score above 100, while half score below 100. There is also a standard deviation of 15 points, resulting in approximately two-thirds of all test takers receiving scores from 85 to 100. 115. Ratings vary, but anything above 120 is generally considered “very high” or “superior,” while below the 80 is called “very low” or “borderline disorder”.
What can we actually learn from IQ scores?
Numerous studies have tried to link IQ scores to all kinds of things. One relationship often found is that people with higher IQ scores tend to be more successful professionally. Some research has suggested that people with higher IQs tend to perform better academically, have more successful careers, and are more likely to enjoy economic comfort.
Certain former US presidents have repeatedly downplayed the IQs of their rivals, while boasting about their own, without providing any evidential support for their claims.
However, this connection has not been found in other research. Another study found that regardless of differences in apparent intelligence, people with better rational thinking skills experienced significantly fewer negative life events, such as serious credit card debt, an unplanned pregnancy, or suspension from school.
Likewise, many manifestations of raw brain power may not be taken into account in standardized intelligence tests, such as creativity, emotional intelligence, or practical technical skills.
Just a few years ago, scientists at University College London identified a general decision-making capacity in young people that was especially strong among people with strong social relationships among their peers. Interestingly, however, there was no correlation between the participants’ IQ and this apparent display of social intelligence.
This begs the question: can a human’s intelligence ever be reduced to a single number?
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It’s a pleasantly simple idea, but one that lends itself to unscientific claims. At the most superficial level, the tempting promise of a comprehensive intelligence score can attract pseudoscience like wasps to a picnic.
For example, Leonardo da Vinci is credited with a remarkable IQ score somewhere between 180 and 220. While there is little doubt that this archetypal “Renaissance man” possessed a truly incredible mind, it is unclear how anyone could come to a solid conclusion about his IQ could come without giving any criticism. he sits down and takes a test.
IQ scores have also been used as a weapon in empty rhetoric. Certain former US presidents have repeatedly downplayed the IQs of their rivals, while boasting about their own, without providing any evidential support for their claims.
IQ’s dark backstory
One of the first cases in which IQ-like tests were widely used was during US military selection during World War I. To determine which recruits should be assigned to which tasks, they were given an intelligence test devised by Robert Yerkes, a psychologist. who later became an important figure in the eugenics movement.
About 1.7 million men were tested, giving researchers a huge amount of data on intelligence and demographics. To some scientists who pored over the results, it seemed to prove a number of truths: intelligence is genetic, innate, and can be accurately reduced to a single number.
Due to rampant bigotry (the US was still fifty years away from eradicating Jim Crow laws) and nationalism of the time, the findings quickly became mired in many ugly debates about race. The results were hijacked by eugenicists to make misleading claims that certain racial groups, namely black people, were fundamentally less intelligent. They did not take into account the wealth of environmental factors that could explain any differences within a population, let alone the fact that many of the recruits tested were first-generation immigrants who did not speak English as a first language.
According to their hypothesis, your financial income, job performance and chances of crime can all be predicted by your IQ.
Race and IQ became falsely linked and were used to fuel eugenics policies aimed at improving the US genetic stock. Yerkes himself, the inventor of the so-called Army Alpha Test, once said, “None of us as civilians can afford to ignore the threat of racial deterioration.”
This idea proved difficult to kill. It bubbled beneath the surface of American society throughout the twentieth centurye century, which erupted in 1994 amid a widespread scandal with the publication of the book The Bell Curve: Intelligence and Class Structure in American Life by psychologist Richard J. Herrnstein and political scientist Charles Murray.
The premise of the book was that IQ had a huge impact on the personal outcomes of people’s lives, even more than their socio-economic status. According to their hypothesis, your financial income, job performance and chances of crime can all be predicted by your IQ.
Academics and journalists alike attacked the book’s findings viciously, claiming that its arguments were poorly substantiated, riddled with errors and reeking of social Darwinism.
Nature versus nurture
Many have since pushed back against the dangerous suggestion that genetics and race can be used as reliable predictors of intellectual ability, pointing out that many analyzes do not take environmental factors into account.
Rather than race alone – which itself is a vague, socially constructed concept – it is much more accurate to understand it through the lens of social disadvantage and poverty. Racial minorities often belong to marginalized communities that have poorer access to health care and education, plus a high risk of discrimination and violence. When these environmental factors are properly taken into account or removed, significant differences in IQ disappear.
It’s not hard to find real-world evidence to support this argument. In 1984, researcher James Flynn made a groundbreaking observation: IQ scores rose rapidly between the 1930s and the late 2020s.e century. In each decade there were differences in IQ points ranging from three to five, for an average increase of 13.8 IQ points over just 46 years.
This jump is far too rapid to be explained in terms of evolution, but it is consistent with broader social and environmental trends such as improved nutrition, declines in infectious diseases, better education and improved living standards.
You can also see this pattern in the developing world today, where researchers have found that IQ points increase rapidly as countries become richer and provide more prosperity for people.
As history shows, IQ scores and general intelligence tests can end up in the wrong hands and be used to reinforce prejudices – something that is in danger of recurring in our increasingly polarized world. Dig a little deeper, however, and you see that these ideas hold a much more promising, less fatalistic lesson for the world: quite simply: better lives make better brains. If we focus our energy on enriching the lives of many, rather than sowing division, humanity’s collective intelligence has the potential to blossom and benefit us all.
CURIOUS magazine is a digital magazine from IFLScience with interviews, experts, deep dives, fun facts, news, book excerpts and much more. Issue 19 is out now.