Experiments that seek to study behavior in voluntary contribution mechanisms are surveyed by Ledyard. Of interest are variables that lead subjects to contribute to a public good when it is in their self interest not to contribute. Experiments conducted by sociologists, social psychologists, political scientists, and economists are discussed. Data reveals that even though economic theory suggests that subjects should not contribute, they generally do in the laboratory. Even in environments conducive to noncooperative behavior the rates of contributions cannot be forced below 10 percent.
Experimenters seek to determine which factors alter the relative rates of cooperation.
There are strong findings that show that cooperative behavior improves when communication is permitted and when the marginal payoff for contributing increases. Repetition of play generally causes contributions to decline. Other factors may be relevant, but the evidence is inconclusive. Ochs' chapter focuses on macroeconomic experiments that examine how subjects coordinate strategies when there are multiple equilibria to a game. Experimenters in this series are not concerned about whether in the early rounds subjects identify and select an equilibrium.