Can’t wait or want it now? Two types of individual differences in delay discounting

Abstract

When choosing between immediate and delayed rewards people discount the subjective value of the latter. This rate of temporal discounting varies in tandem with psychometric impulsiveness and relevant behaviours. Do such individual differences contain distinct styles originating from different underlying processes? Sixty students chose imaginary monetary rewards in a modified delay discounting task where the sooner option was available immediately in one condition but was delayed in another. A mixed model decomposition of areas under the discounting curves revealed two types of individual differences. Delay Sensitivity captured the condition-independent discounting variability while Immediacy Sensitivity isolated the variance induced by the immediacy of the sooner option. Of the two, Immediacy Sensitivity was more strongly related to Big Five facets associated with impulsivity and trait Conscientiousness as well as risky alcohol consumption. The results implicate Delay and Immediacy Sensitivity as reflections of at least partially independent pathways to impulsive behaviour.