DISCOUNTING OF DELAYED REWARDS - A LIFE-SPAN COMPARISON

In this study, children, young adults, and older adults chose between immediate and delayed hypothetical monetary rewards. The amount of the delayed reward was held constant while its delay was varied. All thr-ee age groups showed delay discounting; that is, the amount of an immediate reward judged to be of equal value to the delayed reward decreased as a function of delay. The rate of discounting was highest for children and lowest for older adults, predicting a life-span developmental trend toward increased self control. Discounting of delayed rewards by all three age groups was well described by a single function with age sensitive parameters (all R(2)s > .94). Thus, evert though there are quantitative age differences in delay discounting, the existence of an age-invariant form of discount function suggests that the process of choosing between rewards of different amounts and delays is qualitatively similar across the life span.