Delay, probability, and social discounting in a public goods game

J Exp Anal Behav. 2009 Jan;91(1):61-73. doi: 10.1901/jeab.2009.91-61.


A human social discount function measures the value to a person of a reward to another person at a given social distance. Just as delay discounting is a hyperbolic function of delay, and probability discounting is a hyperbolic function of odds-against, social discounting is a hyperbolic function of social distance. Experiment 1 obtained individual social, delay, and probability discount functions for a hypothetical $75 reward; participants also indicated how much of an initial $100 endowment they would contribute to a common investment in a public good. Steepness of discounting correlated, across participants, among all three discount dimensions. However, only social and probability discounting were correlated with the public-good contribution; high public-good contributors were more altruistic and also less risk averse than low contributors. Experiment 2 obtained social discount functions with hypothetical $75 rewards and delay discount functions with hypothetical $1,000 rewards, as well as public-good contributions. The results replicated those of Experiment 1; steepness of the two forms of discounting correlated with each other across participants but only social discounting correlated with the public-good contribution. Most participants in Experiment 2 predicted that the average contribution would be lower than their own contribution.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Altruism*
  • Choice Behavior
  • Cooperative Behavior
  • Female
  • Humans
  • Interpersonal Relations
  • Male
  • Social Behavior*
  • Young Adult