Altruism in time: social temporal discounting differentiates smokers from problem drinkers.

Rationale: Recent studies on reinforcer valuation in social situations have informed research on mental illness. Social temporal discounting may be a way to examine effects of social context on the devaluation of delayed reinforcers. In prior research with non-drug-using groups, we demonstrated that individuals discount delayed rewards less rapidly (i.e., value the future more) for a group of which they are a member than they do for themselves alone.

Objectives: The current study examined how cigarette smoking and level of alcohol use relate to rates of delay and social temporal discounting.

Methods: In this study, we used crowd-sourcing technology to contact a large number of individuals (N = 796). Some of these individuals were hazardous-to-harmful drinkers (n = 269), whereas others were non-problem drinkers (n = 523); some were smokers (n = 182), whereas others were nonsmokers (n = 614). Delay discounting questionnaires for individual rewards (me now, me later) and for group rewards (we now, we later; me now, we later) were used to measure individuals' discounting rates across various social contexts.

Results: Our analyses found that smokers discounted delayed rewards more rapidly than controls under all conditions. However, hazardous-to-harmful drinkers discounted delayed rewards significantly more rapidly than the non-problem drinkers under the individual condition, but not under the social conditions.

Conclusions: This finding suggests that the use of different abused drugs may be associated with excessive discounting in the individual condition and has selective effects when discounting for a group in the social conditions.