By Rick Nauert PhD Senior News EditorReviewed by John M. Grohol, Psy.D. on April 28, 2011
One of the bastions of psychological testing is the intelligence quotient, a score derived from a standardized test designed to assess intelligence. Conceptually, IQ tests have high reliability, meaning that taking the same test over again and again tends to result in similar scores.
New research has found a correlation between a test-taker’s motivation and performance on an IQ test and, more important, between that performance and a person’s future success.
Dr. Angela Lee Duckworth, an assistant professor of psychology at the University of Pennsylvania, led the research. Duckworth’s team performed two studies, the first being a review or meta-analysis of previous research into the effect of incentives on IQ scores.
The researchers discovered individuals with above-average scores at baseline were marginally influenced by motivation as their scores increased by only about a quarter of a standard deviation, or about four points.
However, for those who had below-average scores, motivation made up almost a whole standard deviation, or around 16 points
The second study involved an experiment in which researchers observed video footage of adolescent boys taking a standard IQ test to rate their motivation and then measured how well they fared in terms of criminal record, job status and educational attainment more than a decade later.
Coders, who were not aware of subjects’ IQ scores or the hypothesis of the study, rated each subject’s motivation based on a standard rubric of behaviors, such as refusing to answer questions or obviously rushing through the test to make it end as quickly as possible.
Ratings of test motivation and IQ scores were about equally predictive of the adult outcomes of years of education, employment status and criminal record.
“What we were really interested in finding out was when you statistically control for motivation, what happens to the predictive power of the IQ tests? What we found is that the predictive power goes down significantly,” Duckworth said.
Duckworth’s research is publioshed in the journal Proceedings of the National Academy of Sciences.
“When people use IQ tests in social science research, where thousands of kids are taking IQ tests where it doesn’t matter to them what they get, what’s the effect of motivation on those scores?” Duckworth said.
“IQ scores are absolutely predictive of long-term outcomes. But what our study questions is whether that’s entirely because smarter people do better in life than other people or whether part of the predictive power (is) coming from test motivation,” Duckworth said.
“This means that for people who get high IQ scores, they probably try hard and are intelligent,” she said. “But for people who get low scores, it can be an absence of either or both of those traits.”