Social institutions regulating group conduct have been regarded as necessary for human cooperation to transcend family bonds. However, many studies in economics and biology indicate that reciprocity based on repeated interaction su_ces to establish cooperation with non-kin. We shed light on the...

The present research experimentally examines the influence of group identity on trust behavior in an investment game. In one treatment, group identity is manipulated only through the creation of artificial (minimal) groups. In other treatments group members are additionally related by outcome...