WHY IQ TESTS DON'T REVEAL WHO'S SMART

Michael Bond, New Scientist - 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 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 someone with a high IQ have these kinds of intellectual deficiencies? Put another way, how can a "smart" person act foolishly? 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 judgments 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. . .

"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.". . .

Indeed, IQ scores have long been criticised as poor indicators of an individual's all-round intelligence, as well as for their inability to predict how good a person will be in a particular profession. The paleontologist Stephen Jay Gould claimed in The Mismeasure of Man in 1981 that general intelligence was simply a mathematical artifact and that its use was unscientific and culturally and socially discriminatory. Howard Gardner at the Harvard Graduate School of Education has been arguing - controversially - for more than 25 years that cognitive capacity is best understood in terms of multiple intelligences, covering mathematical, verbal, visual-spatial, physiological, naturalistic, self-reflective, social and musical aptitudes. . .

As an illustration of how rational-thinking ability differs from intelligence, consider this puzzle: if it takes five machines 5 minutes to make five widgets, how long would it take 100 machines to make 100 widgets? Most people instinctively jump to the wrong answer that "feels" right - 100 - even if they later amend it. When Shane Frederick at the Yale School of Management in New Haven, Connecticut, put this and two similarly counter-intuitive questions to about 3400 students at various colleges and universities in the US - Harvard and Princeton among them - only 17 per cent got all three right. . .