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Intelligence: IQ is only part of the story

By Grant Stewart

Using IQ (intelligence quotient) testing as the main measure of someone’s intelligence is misleading, a new study has found.

What do we know already?

For many years, IQ testing has been thought of as the best measure of someone's intelligence. There’s even an organisation called Mensa, 'The High IQ Society', with membership open to anyone whose IQ is in the top two percent of the population. But a new study questions whether IQ tests can really measure how bright someone is.

Some people argue that IQ testing is biased in favour of certain groups. For example, you could do better or worse in an IQ test, regardless of how clever you are, based on things such as:

  • Education. Being better educated than other people doesn’t necessarily mean you’re more clever than them. But it might help you do better in written tests, as you may be used to doing that kind of work.

  • Social and financial factors. If your parents are well off, or if you live in a wealthy area or a country with a good education system, you may simply have been to a ‘better’ school.

  • Motivation. If there are other things in life more important to you than doing written tests, you may not feel it’s important to do well in them.

Relying too much on the results of IQ tests has led to some people, even whole ethnic or social groups, being thought of as somehow less intelligent than others. Put simply, pen-and-paper testing may only test part of our intelligence while ignoring other measures that don’t fit neatly into a written test.

The researchers looked at the results of online tests from 46,000 people from all over the world. Instead of the traditional IQ test, the people did a wider test that included 12 different measures of mental abilities, such as memory, reasoning, paying attention, and planning.

What does the new study say?

The researchers found that, rather than of a general measure of intelligence that could be measured by an IQ test, a person’s intellectual ability is made up of three components. These were:

  • short-term memory

  • reasoning

  • verbal agility.

The study found that, although these components interact with each other, they are controlled by different parts of the brain. So it’s possible that one person could be very good at one of them, but much worse at the others. This means, the researchers say, that one single test, such as the IQ test, isn’t a broad enough measure of intelligence.

How reliable is the research?

This was a large study that included thousands of people from many different countries. But it still has its limitations. For example, it was an online test, so it could only be done by people who had access to computers. This could have excluded some people of a certain age or level of education, or people in particular countries. The researchers admit that we still know very little about how the brain works. Their study is an interesting step towards knowing more about the brain - but it’s still only one step.

What does this mean for me?

It shouldn’t surprise anyone that written IQ tests are not the only way to measure how bright someone is - we all know someone with a modest education who has done very well in life. But these results may give some encouragement to those of us whose IQ isn’t a cricket score!


Hampshire A, Highfield RR, Parkin BL, et al. Fractionating human intelligence. Neuron. 2012; 76: 1225-1237.

Dec 21, 2012