We experimentally test the social motives behind individual participation in intergroup conflict by manipulating the framing and symmetry of conflict. We find that behavior in conflict depends on whether one is harmed by actions perpetrated by the out-group, but not on one’s own influence on...

We explore in an experiment what leads to the breakdown of partnerships. Subjects are assigned a partner and participate in a repeated public good game with stochastic outcomes. They can choose each period between staying in the public project or working on their own. There is excessive exit as...

This paper provides a new way to identify conditional cooperation in a real-time version of the standard voluntary contribution mechanism. Our approach avoids most drawbacks of the traditional procedures because it relies on endogenous cycle lengths, which are defined by the number of...

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...

We study conditional cooperation based on a sequential two-person linear public good game in which a trusting first contributor can be exploited by a second contributor. After playing this game the first contributor is allowed to punish the second contributor. The consequences of sanctioning...

We report on an experiment designed to explore whether and how anger affects future levels of cooperation. Participants play three consecutive one-shot games. In between two identical two-person public goods games there is a mini dictator game that, depending on the treatment, either gives or...

Cooperation norms often emerge in situations, where the long term collective benefits help to overcome short run individual interests, for instance in repeated Prisonerś Dilemma (PD) situations. Often, however, there are different paths to cooperation, benefiting different kinds of actors to...

We report on an experiment designed to explore whether a written expression of disapproval affects future levels of cooperation. In between two identical public goods games, participants play a mini dictator game that, depending on the treatment, either gives or does not give the recipient the...

Often in cooperative situations, many aspects of the decision-making environment are uncertain. We investigate how cooperation is shaped by the way information about risk is presented (from description or from experience) and by differences in risky environments. Drawing on research from risky...

Unlike previous attempts to implement cooperation in a prisoners' dilemma game with an infinite horizon in the laboratory, we focus on extended prisoners' dilemma games in which a second (pure strategy) equilibrium allows for voluntary cooperation in all but the last round. Our four main...