Does IQ Test Really Measure Intelligence?

Medically Reviewed by Laura J. Martin, MD on December 20, 2012
From the WebMD Archives

Dec. 20, 2012 -- Single tests that measure intelligence quotient, or IQ, may become a thing of the past.

A new study of more than 100,000 participants suggests that there may be at least three distinct components of intelligence. So you could not give a single, unified score for all of them.

Researchers' understanding of the complexities of the human brain has evolved, and so too has the notion of IQ, what it really means, and how it is most accurately captured.

“There are multiple types of intelligence,” says researcher Adam Hampshire, PhD. He is a psychologist at the Brain and Mind Institute Natural Sciences Centre in London, Ontario, Canada. “It is time to move on to using a more comprehensive set of tests that can measure separate scores for each type of intelligence.”

Using Many IQ Tests

In the study, all participants were invited to take a series of 12 online tests that measure memory, reasoning, attention, and planning as well as information on the test takers' background and lifestyle. The entire test takes about 30 minutes to complete.

According to the findings, there are at least three components that affect overall performance on tests. These include short-term memory, reasoning, and verbal recall.

Lifestyle factors count, too. For example, gamers -- or people who play a lot of computer games -- score higher on tests of reasoning and short-term memory. Smokers do poorly on tests assessing short-term memory and vocabulary, while test takers who have anxiety don't do as well on short-term memory tests, the study shows.

What’s more, the study suggests that each type of intelligence may have its basis in a different set of brain areas. Researchers used sophisticated brain scans called functional MRIs to map out these areas. “Potentially, we can measure a more comprehensive set of intelligences," each of which reflects the capacity of a different part of the brain, Hampshire says.

RIP IQ Test?

So should the IQ test that has provided bragging rights for so many be discontinued or discredited?

Not so fast, he says. “Some very valuable research has been carried out using classical IQ testing. However, IQ is a massive oversimplification of the spectrum of human cognitive ability.”

IQ scores may also be somewhat misleading, Hampshire says. “Based on the results of our study, it seems likely that IQ differences will vary in scale or even direction depending on the exact type of intelligence that the test or set of tests rely most heavily upon. I would suggest that it is both more accurate and informative to measure multiple types of intelligence.”

He plans to see if there are other types of intelligence that were not captured in this study.

Hampshire said the findings themselves weren’t all that surprising, but the number of people who took part in the study exceeded expectations. “I had thought a couple of thousand people might log in and participate in the study over the course of six months. Instead, tens of thousands logged in within the space of a few weeks,” he says. It was a remarkably strong response from members of the general public, who gave half an hour or more of their time to support this research.”

John Gabrieli, PhD, professor of brain and cognitive science at MIT in Boston, reviewed the study for WebMD. “This is a really compelling study of an extraordinarily large number of people taking tests with a careful data analysis. It makes the case against the idea that IQ is localized in one part of the brain. We imagine that there is THE test of intelligence, but you can measure it in many ways. One measure may make a person seem super-intelligent, but if they picked another, they may seem average. There are multiple kinds of intelligence that can link to various tasks and different parts of the brain.”

Gayatri Devi, MD, agrees with the new study findings. She is an attending neurologist at Lenox Hill Hospital in New York City. “To come up with one unifying score and use that to determine a person’s overall ability is fraught with problems,” she says. “We need to get away from that.”

The study appears in the journal Neuron.

Show Sources


Gayatri Devi, MD, attending neurologist, Lenox Hill Hospital, New York.

John Gabrieli, PhD, professor,  brain and cognitive science, MIT, Boston.

Hampshire, A. Neuron, study received ahead of print.

Adam Hampshire, PhD, psychologist, Brain and Mind Institute Natural Sciences Centre, London, Ontario, Canada.

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