Existing research supports two opposing mechanisms through which positive mood might affect cooperation. Some studies have suggested that positive mood produces more altruistic, open and helpful behavior, fostering cooperation. However, there is contrasting research supporting the idea that...

We study how punishment influences conditional cooperation. We ask two questions: 1) how does conditional cooperation change if a subject can be punished and 2) how does conditional cooperation change if a subject has the power to punish others. In particular, we disentangle the decision to be a...

We aim to understand the role and evolution of beliefs in the indefinitely repeated prisoner's dilemma (IRPD). To do so, we elicit beliefs about the supergame strategies chosen by others. We find that heterogeneity in beliefs and changes in beliefs with experience are central to understanding...

Subjects who played a payoff-maximising strategy against a computer algorithm ("sophisticates") are more cooperative in a finitely repeated Prisoner's Dilemma than subjects who did not play a payoff-maximising strategy ("naifs"). The difference in cooperation rates increases as the subjects gain...

This paper experimentally investigates whether risk-averse individuals punish less if the outcome of punishment is uncertain than when it is certain. We compare subjects' behavior in two treatments: Certain Punishment in which the prisoner's dilemma game is followed by a punishment stage...

When members of one group encounter a norm violation committed by a member of another group, this antisocial behavior is often handled by picking a random member of the community to which the perpetrator belongs and by applying sanctions to him/her. Despite its prevalence, this kind of...

The indefinitely repeated prisoner's dilemma (IRPD) captures the trade-off between the short-term payoff from exploiting economic partners and the long-term gain from building successful relationships. We aim to understand more about how people form and use beliefs about others in the IRPD. To...

We study experimentally a two-stage compensation mechanism for promoting cooperation in prisoner's dilemma games. In stage 1, players simultaneously choose binding non-negative amounts to pay their counterparts for cooperating in a given prisoner's dilemma game, and then play the prisoner's...