GROUP SELECTION WITH IMPERFECT SEPARATION - AN EXPERIMENT

We experimentally investigate the effect of imperfect separation of groups on group selection and cooperation in a standard prisoner¿s dilemma environment. Subjects can repeatedly choose between two groups, where in one of them an institutionalized norm fosters cooperation. The degree of separation of the two groups is varied between treatments. We find that both, the share of participants that choose into the group where the norm is implemented and the share of participants that cooperate, rise monotonously with the degree of group separation. Furthermore with higher group separation significantly more subjects support the enforcement of the norm.