A number of developmental theories have been proposed that make differential predictions about the links between age and temporal discounting; that is, the valuation of rewards at different points in time. Most empirical studies examining adult age differences in temporal discounting have relied on economic intertemporal choice tasks, which pit choosing a smaller, sooner monetary reward against choosing a larger, later one. Although initial studies using these tasks suggested older adults discount less than younger adults, follow-up studies provided heterogeneous, and thus inconclusive, results. Using an open science approach, we test the replicability of adult age differences in temporal discounting by conducting a preregistered systematic literature search and meta-analysis of adult age differences in intertemporal choice tasks. Across 37 cross-sectional studies (Total N = 104,736), we found no reliable relation between age and temporal discounting (r = -0.081, 95% CI [-0.185, 0.025]). We also found little evidence of publication bias or p-hacking. Exploratory analyses of moderators found no effect of experimental design (e.g., extreme-group vs. continuous age), incentives (hypothetical vs. rewards), amount of delay (e.g., days, weeks, months, or years), or quantification of discounting behavior (e.g., proportion of immediate choices vs. parameters from computational modeling). Additional analyses of 12 participant-level data sets found little support for a nonlinear relation between age and temporal discounting across adulthood. Overall, the results suggest that adult age is not reliably associated with individual differences in temporal discounting. We provide recommendations for future empirical work on temporal discounting across the adult life span.
The behavioral- and neuro-economic process of temporal discounting: A candidate behavioral marker of addiction
