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...

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,...

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

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...

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

In an experiment, a group of strangers was randomly divided in pairs to play a prisoners’ dilemma; this process was indefinitely repeated. Cooperation did not increase when subjects could send public messages amounting to binding promises of future play.

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

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...

We study cooperation in economies of indefinite duration. Participants faced a sequence of prisonerʼs dilemmas with anonymous opponents. We identify and characterize the strategies employed at the individual level. We report that (i) grim trigger does not describe well individual play and there...