This paper presents a formal theory of reciprocity. Reciprocity means that people reward kind actions and punish unkind ones. The theory takes into account that people evaluate the kindness of an action not only by its consequences but also by the intention underlying this action. The theory...

We show in a public goods experiment on three continents that conditional cooperation is a universal behavioral regularity. Yet, the number of conditional cooperators and the extent of conditional cooperation are much higher in the U.S.A. than anywhere else. -- conditional cooperation ; public...

We analyze an experimental public goods game in which group members can endogenously determine whether they want to supplement a standard voluntary contribution mechanism with the possibility of rewarding or punishing other group members. We find a large and positive effect of endogenous...

One lingering puzzle is why voluntary contributions to public goods decline over time in experimental and real-world settings. We show that the decline of cooperation is driven by individual preferences for imperfect conditional cooperation. Many people's desire to contribute less than others,...

We provide a test of the role of social preferences and beliefs in voluntary cooperation and its decline. We elicit individuals' cooperation preferences in one experiment and use them - as well as subjects' elicited beliefs - to explain contributions to a public good played repeatedly. We find...

A growing experimental literature studies the endogenous choice of institutions to solve cooperation problems arising in prisoners' dilemmas, public goods games, and common pool resource games. Participants in these experiments have the opportunity to influence the rules of the game before they...

A growing experimental literature studies the endogenous choice of institutions to solve cooperation problems arising in prisoners' dilemmas, public goods games, and common pool resource games. Participants in these experiments have the opportunity to influence the rules of the game before they...

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...

Ostracism is practiced by virtually all societies around the world as a means of enforcing cooperation and excluding members who show anti-social behaviors or attitudes. In this paper, we use a public goods experiment to study whether groups choose to implement an institution that allows for the...

We study the importance of conditional cooperation in a one-shot public goods game by using a variant of the strategy-method. We find that a third of the subjects can be classified as free riders, whereas 50 percent are conditional cooperators