The Effect of Delay Duration on Delay Discounting Across Adulthood

Abstract

Objectives: Literature about the relationship between age and delay discounting, or the willingness to wait for delayed rewards, is mixed. We posit that some of this heterogeneity may be attributable to inconsistent delay durations across studies. Here we investigate how delay duration influences discounting across adulthood by systematically varying the duration of the delay between the smaller, sooner and the larger, later option.

Methods: 288 healthy participants (age range: 25-84 years) completed an online delay discounting task that probed 12 different time delays across 3 discount rates. Discounting was analyzed in 2 statistical models that treated delay duration as either a categorical or a continuous predictor.

Results: Longer delays were generally associated with decreased discounting. However, this was dependent on both age of the participant and delay duration. Both models revealed that, at short to moderate time delays, older adults discounted less than younger adults. However, at very long delays (5 and 10 years), older adults discounted at similar rates to younger adults.

Discussion: Results suggest that delay length can moderate the relationship between age and discounting. Using delays longer than those tested here (>10 years) could reveal yet another trend (i.e., a reversal) to those found here. Future research should investigate whether this reversal in discounting exists, why it exists, and where the inflection point lies.

Keywords: Cognition; Decision making; Life course and developmental change.

Figure 1.

Delay discounting by delay unit across adulthood. The proportion of sooner options chosen by age and length of delay (days, weeks, months, or years). Higher values represent more discounting. Error bars reflect the 95% confidence interval.

Figure 2.

Delay discounting by delay (in days) across adulthood. The proportion of sooner options chosen by age and length of delay (in days). Higher values represent more discounting. Graphs are faceted by the unit that was presented to participants (days, weeks, months, or years). The length of 7 days is shown on the Days and Weeks graph, representing data from when this length was presented to participants as 7 days (Days facet) and 1 week (Weeks facet). Similarly, 30 days appear on the Weeks (4 weeks) and Months (1 month) graphs while 365 days appear on Months (12 months) and Years (1 year) graphs. Error bars reflect the 95% confidence interval.