We present results from a novel experiment on the effect of a policy designed to encourage cooperation in a prisoner's dilemma game. We find that the effect of this policy on the level of cooperation is greater when it was chosen democratically by the subjects than when it was exogenously...

A novel experiment is used to show that the effect of a policy on the level of cooperation is greater when it is chosen democratically by the subjects than when it is exogenously imposed. In contrast to the previous literature, our experimental design allows us to control for selection effects...