Time discounting over the lifespan and Age-Related Changes in the Episodic Simulation of Future Events

Two articles (2004 & 2008) which provide an insight into the processes which may be involved in determining discount rates over time. Their is some cross-cultural evidence to suggest that a U-shaped relationship exists between discount rates and age whereby middle-aged people discount less than either younger or older individuals. One set of contributing factors may be impulsivity/sensation seeking in younger participants and memory based problems in imagining the future in older participants (as described in the second article from Psychological Science 2008).

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.

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Age-Related Changes in the Episodic Simulation of Future Events

ABSTRACT—Episodic memory enables individuals to recollect past events as well as imagine possible future scenarios. Although the episodic specificity of past events declines as people grow older, it is unknown whether the same is true for future events. In an adapted version of the Autobiographical Interview, young and older participants generated past and future events. Transcriptions were segmented into distinct details that were classified as either internal (episodic) or external. Older adults generated fewer internal details than younger adults for past events, a result replicating previous findings; more important, we show that this deficit extends to future events. Furthermore, the number of internal details and the number of external details both showed correlations between past and future events. Finally, the number of internal details generated by older adults correlated with their relational memory abilities, a finding consistent with the constructive-episodic-simulation hypothesis, which holds that simulation of future episodes requires a system that can flexibly recombine details from past events into novel scenarios.

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