IQ scores reflect motivation as well as ‘intelligence’

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Ever since there have been IQ tests, people have debated what they actually measure. Is it “intelligence”, is it an abstract combination of mental abilities, or is it, as Edwin Boring said, “the capacity to do well in an intelligence test”? Regardless of the answer, studies have repeatedly shown that people who achieve higher scores in IQ tests are more likely to do well in school, perform well in their jobs, earn more money, avoid criminal convictions, and even live longer. Say what you like about the tests, but they have predictive power.

However, Angela Lee Duckworth from the University of Pennsylvania has found that this power is overrated. The link between our IQs and our fates becomes muddier when we consider motivation – an aspect of test-taking that is often ignored. Simply put, some people try harder in IQ tests than others. If you take this into account, the association between your IQ and your success in life becomes considerably weaker. The tests are not measuring intelligence alone, but also the desire to prove it.

Many standardised tests assume that the people who take them are alert and motivated. As such, their scores reflect the height of their abilities. IQ tests are no different. The questions are ordered by difficulty to keep people’s morale up. Edward Thorndike, a pioneer of intelligence testing, wrote that “all our measurements assume that the individual in question tries as hard as he can to make as high a score as possible”, although he admitted that no one knew if that was the case.

To look at how motivation affects IQ scores, Duckworth reviewed 25 previous studies, which included a total of 2,008 people. She found that people achieved higher IQ scores on average if they were given material incentives to take the tests, such as money or sweets, particularly if they had above-average IQs anyway. This alone suggests that motivation can skew the results of the tests.

Next, Duckworth looked at the scores of 508 young boys who had taken an IQ test in 1987. The boys were part of the Pittsburgh Youth Study, and researchers kept in touch with them into adulthood, for at least 12 years after the original test. As usual, their scores predicted their eventual academic performance, the number of years they spent in education, their odds of being employed as adults, and their number of criminal convictions.

But there was more. The original tests were all delivered verbally and the sessions were filmed. Duckworth recruited three independent researchers to review the footage for signs of low motivation, such as refusing to take part, or wanting the session to end. The team found that boys with lower IQ scores were also less motivated when they took the test, and their degree of motivation also predicted the course of their lives. Accounting for motivation weakened the link between IQ and life-success, especially for employment and criminal convictions.

Duckworth says, “It is important not to overstate our conclusions.” IQ tests can still predict other aspects of our lives. Motivation reduces that predictive power, but it doesn’t destroy it altogether. The point is that people with above-average IQs also tend to try harder on IQ tests, and they do so more consistently. Duckworth writes, “These findings imply that earning a high IQ score requires high intelligence in addition to high motivation. Lower IQ scores, however, might result from either lower intelligence or lack of motivation.”

The problem, as ever, lies in making too much of the test results, in seeing them as a sign of natural ability and future potential. After all, motivation is itself affected by a person’s background, and their beliefs in their future options and their chances of success. It could partially explain differences in test scores between people of different genders, social backgrounds and nationalities.

If you think it’s obvious that motivation would confound the results of IQ tests, then Robert Stenberg, who studies intelligence at Oklahoma State University, agrees with you. “D’uh!”, he says. Sternberg thinks that Duckworth has produced a “great research study” but adds, “To almost anyone except some subset of psychologists who study IQ testing, it will come as little surprise that motivation is an extremely powerful determinant of performance in school and in life. Most employers, for example, are at least as eager to know about job applicants’ motivation as they are to know about their cognitive skills.  Teachers also know that ability without high motivation typically results in little success in a challenging curriculum.”

Duckworth herself recognises that people who actually administer the tests will be well aware of the issue of motivation. She says, “Where the problem lies, in our view, is in the interpretation of IQ scores by economists, sociologists, and research psychologists who have not witnessed variation in test motivation firsthand. [They] might erringly assume that a low IQ score invariably indicates low intelligence.”

Is this view common? Sternberg thinks so, pointing to the fact that Duckworth’s study was newsworthy enough to be published in PNAS, one of the world’s most prestigious scientific journals. “[This shows] how off-track our society has gone in its acceptance of commercial persuasive appeals to buy into standardized tests as some kind of panacea for predicting almost any outcome in life that we value.

“The irony of the study is that it shows the tests indeed can be useful, but as joint measures of cognitive skills and motivation.  The tests also indirectly measure many other variables, such as quality of schooling, type of socialization in the home, and parents’ ability to provide their children with a home environment that fosters the kinds of skills that tests measure.  IQ tests, like all tests, are agglomerate measures of many things.  They are not pure measures of some kind of “intelligence” or anything else.

“Ultimately, it would be desirable if we recognized that many skills are required for success in life and if we grew beyond using contemporary tests, which are minor cosmetic variants of tests used a century ago.  (Imagine where we would be if our medical testing were essentially the same as it was 100 years ago.)  Instead of limiting ourselves to narrow standardized tests, we might seek as well directly to assess motivation as well as creativity, practical skills, wisdom, and even ethics. If we did, we might find our society advancing to levels of economic productivity and, for that matter, well-being that we previously believed to be out of reach.“

Reference: Duckworth, Quinn, Lynam, Loeber & Stouthamer-Loeber. 2011. Role of test motivation in intelligence testing. PNAS http://dx.doi.org/10.1073/pnas.1018601108

Image by Luc Legay

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