We study the. Incentive effects of endogenous group formation in a voluntary contributon experiment. Subjects are given information on the past contributions of others and allowed to express a preference for partners. On the basis of the stated preferences new groups are formed. We find that the...

We present results from a novel experiment on the effect of a policy designed to encourage cooperation in a prisoner's dilemma game. We find that the effect of this policy on the level of cooperation is greater when it was chosen democratically by the subjects than when it was exogenously...

The prospect of receiving a monetary sanction for free riding has been shown to increase contributions to public goods. We ask whether the impulse to punish is unresponsive to the cost to the punisher, or whether, like other preferences, it interacts with prices to generate a conventional demand...