Having a high IQ doesn’t necessarily mean you’re smart.
Far from it, says Michael Bond (New Scientist, 31st October 2009).

Is George W.Bush stupid? It's a question that occupied a good many minds of all political persuasions during his turbulent eight-year presidency. The strict answer is no. Bush's IQ score is estimated to be above 120, which suggests an intelligence in the top 10 per cent of the population. But this, surely, does not tell the whole story.

Even those sympathetic to the former president have acknowledged that as a thinker and decision-maker he is not all there. Even his loyal speechwriter David Frum called him glib, incurious and "as a result ill-informed". The political pundit and former Republican congressman Joe Scarborough accused him of lacking intellectual depth, claiming that compared with other US presidents whose intellect had been questioned, Bush junior was "in a league by himself". Bush himself has described his thinking style as "not very analytical".

How can a "smart" person act foolishly?

How can someone with a high IQ have these kinds of intellectual deficiencies? Keith Stanovich, professor of human development and applied psychology at the University of Toronto, Canada, has grappled with this apparent incongruity for 15 years. He says it applies to more people than you might think. To Stanovich, however, there is nothing incongruous about it. IQ tests are very good at measuring certain mental faculties, he says, including logic, abstract reasoning, learning ability and working-memory capacity - how much information you can hold in mind.

But the tests fall down when it comes to measuring those abilities crucial to making good judgements in real-life situations. That's because they are unable to assess things such as a person's ability to critically weigh up information, or whether an individual can override the intuitive cognitive biases that can lead us astray.

This is the kind of rational thinking we are compelled to do every day, whether deciding which foods to eat, where to invest money, or how to deal with a difficult client at work. We need to be good at rational thinking to navigate our way around an increasingly complex world. And yet, says Stanovich, IQ tests - still the predominant measure of people's cognitive abilities - do not effectively tap into it. "IQ tests measure an important domain of cognitive functioning and they are moderately good at predicting academic and work success. But they are incomplete. They fall short of the full panoply of skills that would come under the rubric of 'good thinking'."

IQ isn't everything

"A high IQ is like height in a basketball player," says David Perkins, who studies thinking and reasoning skills at Harvard Graduate School of Education in Cambridge, Massachusetts. "It is very important, all other things being equal. But all other things aren't equal. There's a lot more to being a good basketball player than being tall, and there's a lot more to being a good thinker than having a high IQ."

IQ tests and their proxies, which are designed to measure a factor known as general intelligence, are used by many businesses and colleges to help select the "best" candidates, and also play a role in schools and universities. "IQ tests determine, to an important degree, the academic and professional careers of millions of people in the US," Stanovich says in his book, What Intelligence Tests Miss (Yale University Press, 2008). He challenges the "lavish attention" society bestows on such tests, which he claims measure only a limited part of cognitive functioning. "IQ tests are overvalued, and I think most psychologists would agree with that," says Jonathan Evans, a cognitive psychologist at the University of Plymouth, UK.

The difference between intelligence and rational thinking

Stanovich and other researchers into rational thinking are not trying to redefine intelligence, which they are happy to characterise as those mental abilities that can be measured by IQ tests. Rather, they are trying to focus attention on cognitive faculties that go beyond intelligence - what they describe as the essential tools of rational thinking. These, they claim, are just as important as intelligence to judgement and decision-making. "IQ is only part of what it means to be smart," says Evans.

Your brain’s information processing system

We encounter problems like these in various guises every day. Without careful reasoning we often get them wrong, probably because our brains use two different systems to process information. One is intuitive and spontaneous; the other is deliberative and reasoned.

Intuitive processing can serve us well in some areas - choosing a potential partner, for example, or in situations where you've had a lot of experience. It can trip us up in others, though, such as when we overvalue our own egocentric perspective. Deliberative processing, on the other hand, is key to conscious problem-solving and can help us override our intuitive tendencies if they look like leading us astray.

The problem with IQ tests is that while they are effective at assessing our deliberative skills, which involve reason and the use of working memory, they are unable to assess our inclination to use them when the situation demands. This is a crucial distinction: as Daniel Kahneman at Princeton University puts it, intelligence is about brain power whereas rational thinking is about control. "Some people who are intellectually able do not bother to engage very much in analytical thinking and are inclined to rely on their intuitions," explains Evans. "Other people will check out their gut feeling and reason it through and make sure they have a justification for what they're doing." An IQ test cannot predict which of these paths someone will follow, hence the George W. Bush incongruity of people who are supposedly smart acting foolishly.

The idea that Bush is just one foolish smart person among many, and that intelligence is a poor predictor of ‘good thinking’, comes from a series of recent experiments that compared the performances of people of a range of intellectual abilities on rational-thinking tasks. In a study published last year, Stanovich and Richard West of James Madison University in Harrisonburg, Virginia, found there was no correlation between intelligence and a person's ability to avoid some common traps of intuitive-thinking (Journal of Personality and Social Psychology, vol 94, p 672).

On certain types of thinking tasks, such as those involving number ratios, probabilities, deductive reasoning and the use of hindsight, intelligent people do perform better, Stanovich and others have found. This is particularly true when any intuitive pitfalls are obvious, especially if a correct answer depends on logic or abstract reasoning - abilities that IQ tests measure well. But most researchers agree that, overall, the correlation between intelligence and successful decision-making is weak. The exception is when people are warned that they might be vulnerable to a thinking bias, in which case those with high IQs tend to do better. This, says Evans, is because while smart people don't always reason more than others, "when they do reason, they reason better".

What the critics say

The idea that IQ is a poor measure of rationality is not without its critics, though. Christopher Ferguson, who studies the genetic and environmental factors behind human behaviour at Texas A&M International University in Laredo, says that since those with high IQ tend to live longer and earn more, we should assume that intelligent people are more rational. "They tend to have more knowledge with which to make better decisions," he says.

Yet Wändi Bruine de Bruin at Carnegie Mellon University in Pittsburgh, Pennsylvania, has shown that intelligence cannot be the only factor that dictates whether someone is a good thinker and decision-maker. In a study of 360 Pittsburgh residents aged between 18 and 88, her team found that, regardless of differences in intelligence, those who displayed better rational-thinking skills suffered significantly fewer negative events in their lives, such as being in serious credit card debt, having an unplanned pregnancy or being suspended from school (Journal of Personality and Social Psychology, vol 92, p 938).

Andrew Parker, now with the Rand Corporation in Pittsburgh, and Baruch Fischhoff at Carnegie Mellon found a similar association among adolescents. Those who scored higher on a test of decision-making competence drank less, took fewer drugs and engaged in less risky behaviour overall (Journal of Behavioral Decision Making, vol 18, p 1). This suggests that rational thinking may be more important than intelligence for positive life experiences, Fischhoff says.

The good news

The flip side is that everyone can improve their rational thinking and decision-making skills. Richard Nisbett at the University of Michigan in Ann Arbor and others discovered that just half an hour's training in statistical reasoning can improve a person's ability to use rational thinking in everyday situations. And we don't need formal training to improve: there are many tricks we can teach ourselves, says Perkins (see "How to avoid making foolish decisions").

Answers: 1) 5 cents, 2) 5 minutes, 3) 47 days