Relationship between cooperation in an iterated prisoner's dilemma game and the discounting of hypothetical outcomes.

A number of authors have proposed that preference for a larger, delayed reward in delay discounting is similar to cooperation in a repeated prisoner's dilemma game versus tit-for-tat. This proposal was examined by correlating delay-discounting (Experiment 1) and probability-discounting (Experiment 2) rates for hypothetical monetary gains and losses with performance in a repeated prisoner's dilemma game. Correlations between rate of delay discounting (discounting parameters and area under the curve) and proportion of cooperation in the repeated prisoner's dilemma game versus tit-for-tat were significant across three magnitudes, and correlations were generally higher with discounting for losses than with that for gains. As was expected, correlations between rate of delay discounting and performance versus a random strategy in the prisoner's dilemma game were not significant. Correlations between rate of probability-discounting and cooperation rate in a repeated prisoner's dilemma game versus neither a tit-for-tat nor a random strategy were significant.