In experiments, people behave more cooperatively when they are aware of an external threat, while in the field, we observe surprisingly high levels of cooperation and altruism within groups in conflict situations such as civil wars. We provide an explanation for these phenomena. We introduce a...

In experiments, people behave more cooperatively when they are aware of an external threat, while in the field, we observe surprisingly high levels of cooperation and altruism within groups in conflict situations such as civil wars. We provide an explanation for these phenomena. We introduce a...

Previous work has found that in social dilemmas, the selfish always free-ride, while others will cooperate if they expect their peers to do so as well. Outcomes may thus depend on conditional cooperators’ beliefs about the number of selfish types. An early round of the game may be played...

Do individuals trained in law enforcement punish or reward differently from typical student subjects? We analyze norm enforcement behavior of newly appointed police commissioners in both a Voluntary Contribution Mechanism game and a Common Pool Resource game. Our experimental design includes...

We investigate the impact of various audit schemes on the future provision of public goods, when contributing less than the average of the group is sanctioned exogenously and the probability of an audit is unknown. We study how individuals update their beliefs about the probability of being...

In experiments, people behave more cooperatively when they are aware of an external threat, while in the field, we observe surprisingly high levels of within - group cooperation in conflict situations such as civil wars. We provide an explanation for these phenomena. We introduce a model in...

Using a negatively framed public good game, we study the cooperative behavior of individuals who reintegrate their group after being excluded by their peers. We manipulate the length of exclusion and whether this length is imposed exogenously or results from a vote. We show that people are...