Time discounting over the lifespan

Several theories of intertemporal choice predict systematic age differences in the rate at which people discount the future. Different theories, however, predict different patterns: one predicts that discounting will decrease over the lifespan, so that young people will discount more than the middle aged or elderly, another suggests it will increase over the lifespan, and yet another suggests that the middle-aged will discount less than either the young or the old. We conduct a study testing these predictions. 123 respondents between the ages of 19 and 89 made a large number of time discounting decisions on both computerized and paper-and-pencil questionnaires. The results suppported the view that older people discount more than younger ones, and that middle aged people discount less than either group. This finding appears to contrast with earlier work (Green, Fry, & Myerson, 1994) but, as we show, our results are remarkably congruent with that study. We conclude by considering whether our results can be reconciled with the fact that young people commit more apparently impulsive acts than do the elderly.