The fact that IQ test performance is a strong predictor of outcomes later in life, including career success and longevity, is well established. However, a new study led by Angela Duckworth at the University of Pennsylvania argues the predictive power of IQ tests isn’t all about intelligence. IQ tests also measure motivation, Duckworth and her colleagues claim, and motivation is independently predictive of various life outcomes (PNAS:tinyurl.com/634kdgc).
The researchers first performed a meta-analysis of 46 studies that had compared IQ test performance with and without incentives. This data, together involving more than 2000 people, showed that financial and other incentives made a large difference to performance, especially to lower IQ scorers.
Next, Duckworth’s team focused on videos taken of hundreds of boys performing an IQ test at age 12 in the 1980s. These clips were analysed for signs of motivation, or lack of it, and the boys were followed up years later, once they were in their twenties. These investigations revealed that the link between earlier IQ and later life outcomes was significantly reduced once earlier motivation levels were taken into account, especially for non-academic outcomes such as crime and employment.
‘[T]est motivation may be a serious confound in studies including participants who are below-average in IQ and who lack external incentives to perform at their maximal potential,’ the researchers warned. However, they also conceded that their findings should be kept in perspective. IQ test performance remained predictive of later outcomes, even after motivation was controlled for, and it was a stronger predictive factor than motivation.
‘Our conclusions may come as no surprise to psychologists who administer intelligence tests themselves,’ Duckworth and her colleagues concluded. ‘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 first hand.’
SBS School Psychology Department 