We study the emergence of norms of cooperation in experimental economies populated by strangers interacting indefinitely. Can these economies achieve full efficiency even without formal enforcement institutions? Which institutions for monitoring and enforcement facilitate cooperation? Finally,...

What institutions can sustain cooperation in groups of strangers? Here we study the role of monetary systems. In an experiment, subjects sometimes needed help and sometimes could incur a cost to help an anonymous counterpart. In the absence of money, the intertemporal exchange of help, which...

Social norms of cooperation are studied under several forms of communication. In an experiment, strangers could make public statements before playing a prisoner's dilemma. The interaction was repeated indefinitely, which generated multiple equilibria. Communication could be used as a tool to...

Under what conditions can cooperation be sustained in a network of strangers? Here we study the role of institutions and uncover a new behavioral foundation for the use of monetary systems. In an experiment, anonymous subjects could cooperate or defect in bilateral random encounters. This...

We study intertemporal choices through an experiment that elicits a subject's plan and then tracks its implementation over time. There are two main results. When facing a costly task to be completed under a deadline, two thirds of subjects prefer anticipating it rather than postponing it. Choice...

We study individual behavior of students and workers in an experiment where they repeatedly faced with the same cooperative task. The data show that clerical workers differ from college students in overall cooperation rates, strategies adopted, and use of punishment opportunities. Students...

This study reveals the existence of a causal link between the availability of money and an expanded scale of interaction. We constructed an experiment where participants chose the group size, either a low-value partnership or a high-value group of strangers, and then faced an intertemporal...

Does monitoring past conduct facilitate intertemporal cooperation? We designed an experiment characterized by strategic uncertainty and multiple equilibria where coordinating on the efficient outcome is a challenge. Participants, interacting anonymously in a group, could pay a cost either to...

We study time preferences in a real-effort experiment with a one-month horizon. We report that two thirds of choices suggest negative time preferences. Moreover, choice reversal over time is common even if temptation plays no role. We propose and measure three distinct concepts of choice...