[Expectations of a generalized exchange system and ingroup favoritism: an experimental study of bounded reciprocity].

Yamagishi, Jin, and Kiyonari (1999) recently proposed an alternative account of ingroup favoritism in the minimal group experiment (MGE). According to the hypothesis, expectation of "bounded generalized reciprocity" that a generalized exchange system exists in the group is the primary source of the favoritism, not motivation for social identity. Partly replicating the Yamagishi et al. study, the current study with 73 participants added further evidence; they did not cooperate more with an ingroup partner than with an outgroup partner, if they believed that the partner did not know the participant's membership, regardless of the partner's membership. It was further shown that expectation of cooperation by the partner in itself was not enough to raise the participant's cooperation level. Based on these findings, it was concluded that ingroup favoritism found in MGE was a result of the shared group identity that triggered the definition of the situation as a group situation where a generalized exchange system existed for ingroup members.