Adolescents’ performance on delay and probability discounting tasks: Age, intelligence, executive functioning, externalising behaviour

This study reflects the attempt to integrate delay discounting into existing psychological models around executive functioning, intelligence, and emotional regulation.

Abstract:
Healthy adolescents, ages 9–23, completed delay and probability discounting tasks and measures of verbal and non-verbal intelligence, executive functioning, and self-reported internalizing and externalizing behavior. Delay but not probability discounting decreased with age. Delay discounting was also associated with verbal intelligence and Go–NoGo and Iowa Gambling Task performance. Probability discounting was associated only with externalizing behavior. Findings conform to an accumulation of evidence that while delay and probability discounting may have some overlapping components, they also reflect some fundamentally different processes in this age group.

They found a nice correlation of .35 between delay discounting and errors of commission (responding on a no-go trial) indicating that the ability to inhibit a response is very much central to delay discounting. The authors are pointing to IQ as the main variable in accounting for differences in delay discounting as this is in line with the de Wit et al (2007) study which had a larger sample. For parsimony and methodological reasons I would have liked to have seen the Go-NoGo variable put into the regression before IQ as it was correlated to a greater extent with delay discounting and it is possible that it is tapping into a fundamental process which is central to the development and operation of intelligence. The discussion was framed completely around this contribution of IQ which may have been an artefact of what looked to me a biased regression procedure.

The finding in regard to IQ echoes some recent larger scale retrospective epidemiological studies showing that lower childhood IQ increases the chance of mortality in middle-age and that this is largely due to an increased likelihood of engaging persistently in health risk behaviours: Childhood IQ in relation to risk factors for premature mortality in middle-aged persons: the Aberdeen Children of the 1950s study. I wonder will Go-NoGo performance predict mortality in 40 years.. It's a terribly tedious task to complete for anyone who's had the opportunity but you have to consider the benefits of examining such a basic process in comparison to something like IQ which is such a broad concept that doesn't translate easily to theory-related neuronal processes unless you go through the medium of executive function..

Olson et al. (2007). Adolescents’ performance on delay and probabilitydiscounting tasks: Contributions of age, intelligence, executive functioning, and self-reported externalizing behavior