Groups of five players participated in a social dilemma game in which each player receives a monetary endowment and then chooses whether to contribute it to a monetary public good. The good is provided to all group members if at least three contributions are made; it is not provided, otherwise. Experiment 1 showed that the simultaneous protocol of play—where decisions are made privately and anonymously—is significantly less effective in solving the dilemma than the sequential protocol—where decisions are made sequentially with complete information about previous decisions in the sequence. Experiment 2 replicated this finding and, in addition, showed that the sequential protocol with only information about previous noncooperative choices is significantly more effective in solving the dilemma than the sequential protocol with only information about previous cooperative choices.
