Extensive experimental research has been devoted to the study of behaviour in laboratory settings related to public goods, common-pool resources, and other social dilemmas. When subjects are anonymous and not allowed to communicate, they tend not to cooperate. To the surprise of game theorists, however, simply allowing subjects to communicate in a laboratory setting enables them to achieve far more cooperative outcomes. This finding has now been replicated in many laboratory experiments in multiple countries and in some initial field experiments. Carefully conducted laboratory experiments do have strong internal validity. External validity, however, requires further research beyond the initial field experiments that have already been conducted. In this paper, we report on a series of common-pool resource field experiments conducted in eight indigenous communities in India that have very long traditions of shared norms and mutual trust. Two experimental designs were used in all eight villages: a “no-communication” game that was repeated in ten rounds where no one was allowed verbal or written communication and a “communication game” in which the same five participants were allowed to communicate with each other at the beginning of each round before making their decisions. The findings from these field experiments are substantially different from the findings of similar experiments conducted in experimental laboratories. Subjects tended to cooperate in the first design even in the absence of communication. The shared norms in these indigenous communities are so deeply embedded that communication is not needed to adopt cooperative decisions. Communication does, however, tend to homogenize group and individual outcomes so that communities that are overly cooperative tend to reduce cooperation slightly and those with small deviations in the other direction tend to move toward the optimal solution.
