Unbounded indirect reciprocity: Is reputation-based cooperation bounded by group membership?

Bounded generalized reciprocity (BGR) predicts that people cooperate to maintain a positive reputation with
ingroup, but not outgroup, members—and this explains ingroup favoritism in cooperation. We propose that
the benefits of maintaining a positive reputation are not limited by group boundaries and so people may cooperate
to maintain a good reputation among outgroup members when they will meet and interactwith members of
that group again. According to this unbounded indirect reciprocity perspective, reputation can promote cooperation
with both ingroup and outgroup members. Alternatively, social identity theory (SIT) favors social identity
versus reputation as an explanation for cooperation among ingroup members. We test these hypotheses across
five studies (Ns = 619, 607, 613, 360, and 615) that manipulate reputation, social identification, and partner's
group membership in a cooperative decision making task. Across our studies, people were more cooperative
with both ingroup and outgroup members when their reputation was at stake (Studies 1–5), and reputational
concern mediated the effect of cues of gossip on cooperation in interactions with ingroup and outgroup members
(Studies 1–4). Social identification did not affect cooperation with ingroup members.We discuss the theoretical
and practical implications of the indirect benefits of cooperation that can transcend group boundaries.