Penn psychologist's research suggests motivation is a factor in IQ

Thomas Edison famously quipped that genius is 1 percent inspiration and 99 percent perspiration. A study this week suggests that perspiration is important not just for creating new inventions but for getting a good score on an IQ test.

A team led by University of Pennsylvania psychologist Angela Duckworth examined data collected from dozens of studies and concluded that test-takers who were motivated by money scored considerably better. The role of motivation was especially important at the lower end of the spectrum, where a financial incentive could raise IQ as much as 15 points.

"This is a very important paper," said University of Michigan psychologist Richard Nisbett, who was not involved in the study. "I was shocked. I wouldn't have thought that incentives would have made such a big difference."

While he agrees that IQ is correlated with academic performance, the paper makes a case that differences in effort and motivation account for a part of people's IQ scores.

The concept of IQ has become mired in controversy for decades, and psychologists still disagree over whether IQ differences are set more by nature or nurture.

Often, views on IQ tend to line up with politics, with those on the right side of the spectrum more likely to see IQ as an important, stable, inherited quantity, said Nisbett, author of the recent book Intelligence and How to Get It.

A universal definition remains elusive. "The more I work in the field, the more I don't have a clear idea of what intelligence is," Nisbett said. He agrees more or less with a definition laid out by University of Delaware psychologist Linda Gottfredson: the ability to reason, plan, solve problems, think abstractly, learn quickly and from experience, and make sense of our surroundings.

What is unclear is whether such a range of abilities can be reduced to a single number and measured by a test.

Harvard University paleontologist Stephen Jay Gould didn't think so. In his 1981 book, The Mismeasure of Man, he attempted to dispel the notion of general intelligence - the quality that IQ tests are meant to measure.

Duckworth said that despite this and other attacks, IQ was still taken seriously in academic circles.

And she does not question the body of evidence that higher IQ scores are correlated not only with academic achievement but also with years of education, employment, and with not having a criminal record.

But IQ tests, she said, may get their predictive power from measuring something more than innate brain power. Writing in this week's issue of the Proceedings of the National Academy of Sciences, she described the effect of money incentives, as well as an experiment in which a group of trained observers measured apparent motivation among 250 adolescent boys taking an IQ test.

When corrected for differences in motivation, the tests did not predict employment or crime as clearly, suggesting that motivation mattered more.

In other words, the types of motivated, competitive people who are likely to work hard on any test are also more likely to succeed in school and work.

Michigan's Nisbett said motivation has not been well appreciated. Many scientists consider IQ a measure of something more concrete and stable, "as if you could dip a thermometer in the brain."

His work shows that IQ is influenced by school and home life. Poorer children lose IQ points over the summer while richer ones gain points, presumably because they are better able to read and learn outside school.

"Much of the IQ differences between social classes is due to summer," he said.

Another thing hard to square with genetics, he said, is the observation that IQ scores have been rising since the early 20th century. This rise, called the Flynn effect, is steep enough that a person who tested average today would have been considered gifted two generations ago.

"That's absolutely massive," he said of the shift, which he attributes to more emphasis in schools on skills measured by IQ tests.

Producing a more coherent, understanding of intelligence won't be easy. It may take both inspiration and perspiration along the way.