We study cooperation within and between groups in the laboratory, comparing treatments in which two groups have previously been (i) in conflict with one another, (ii) in conflict with a different group, or (iii) not previously exposed to conflict. We model conflict using an inter-group Tullock...

We study cooperation within and between groups in the laboratory, comparing treatments in which two groups have previously been (i) in conflict with one another, (ii) in conflict with a different group, or (iii) not previously exposed to conflict. We model conflict using an inter-group Tullock...

Interrelated global crises - climate change, pandemics, loss of ecosystem services and biodiversity - pose risks that demand collective solutions. Uncertainty about others' behavior, coupled with the dependence on some to take collective efforts to mitigate risks for all (e.g. conservation of...

We study cooperation in an environment where public good providers face the decision to accept a newcomer to their group. A bottom-up process for accepting new members to social groups reveals individual preferences to include newcomers. Alternatively, inclusion can be decided in a top-down...

Empirical evidence is provided for the importance of non-reciprocal pro-social behavior of individuals in an anonymous, n-person pure public good setting. A unique panel data set of 136,000 observations is matched with an extensive survey. Even under anonymous conditions, a large number of...

Explaining the evolution and maintenance of cooperation among unrelated individuals is one of the fundamental problems in biology and the social sciences. Recent experimental evidence suggests that altruistic punishment is an important mechanism to maintain cooperation among humans. In this...

We report experimental findings on the role of charitable promises in bargaining settings. We vary the enforceability of such promises within variants of ultimatum games where the proposer suggest a split between himself, the responder and a char-itable donation. By reneging on initial pledges,...

We use an experiment to test the hypothesis that groups consisting of like-minded cooperators are able to cooperate irrespective of punishment and therefore have a lower demand for a costly punishment institution than groups of like-minded free riders, who are unable to cooperate without...

We conduct a contribution game for a real public good and show that when the contributors value the real public good highly, they increase their contributions in each round. Thus, contrary to previous literature, free riding decreases over rounds and the end-game effect is reversed. -- public...