PERSONALITY AND SOCIAL PSYCHOLOGY BULLETIN Kurzban et al. / REAL-TIME PUBLIC GOODS Incremental Commitment and Reciprocity in a Real-Time Public Goods Game

Allowing players in public goods games to make small incremen-tal commitments to contributing to the good might facilitate cooperation because it helps to prevent players from being “free ridden, ” contributing more to the public good than other group members. Two experiments using a real-time version of the vol-untary contribution mechanism were conducted to investigate the hypothesis that players are generally willing to contribute public goods conditional on beliefs that others are doing so at similar levels. Experiment 1 provided evidence that affording a strategy of commitment can increase the production of public goods. Experiment 2 provided evidence that most players are willing to contribute to the public good at a level at or slightly above the contribution of the lowest contributor in the group. Both experiments point to inequity aversion as an important ele-ment of play in public goods games