Smart or Determined? Examining The Role of Motivation in IQ Tests


Intelligence tests are meant to tell you something about a person’s inherent abilities. But what if the results are distorted by the motivation to perform well? That would undermine the tests’ validity and have important implications for their use in education and recruitment.

A simple way to find out whether motivation affects intelligence test performance is to offer people a financial incentive for doing well and see if this helps them get a higher score. A paper in the British Journal of Psychology has done this, finding that while a financial incentive boosted people’s self-declared effort levels, it failed to lift their performance. This result is good news for the validity of intelligence testing. Or as the paper’s author, Gilles Gignac at the University of Western Australia, put it: “The position of a causal effect of test-taking motivation on intelligence test performance in adults does not, yet, appear to be clearly tenable”.

The background to this research is a controversial meta-analysis published in 2011 by Angela Duckworth (of Grit fame) and her colleagues which suggested that motivation distorts IQ test performance, thereby challenging the validity of IQ tests as a pure measure of ability. However, only 2 of the 46 samples included in that meta-analysis featured adults, and the findings from those adult samples were inconclusive.

To plug this gap, Gignac recruited 99 undergrads and asked them to complete various intelligence tests, including of basic “processing speed”, working memory, fluid intelligence (measured using Raven’s progressive matrices) and crystallised intelligence (based on a vocab test). To read more from Christian Jarrett, click here.

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