Collective action in culturally similar and dissimilar groups: an experiment on parochialism, conditional cooperation, and their linkages

This study examines the effects of ingroup favoritism and outgroup hostility (“parochialism”), as well as of conditionally cooperative strategies, in explaining contributions to experimental public goods games. The experimental conditions vary group composition along two culturally inheritable traits (political party preference and religious affiliation) and one trivial, “minimal” trait (birth season). We contrast ingroup, outgroup, and random group conditions and investigate the relation between the own contribution to the public good and the expectations about other group members' behavior in each one of them. We find evidence for ingroup favoritism but no support for a separate tendency towards outgroup hostility. Further, conditional cooperation and ingroup bias are, to some extent, linked. Subjects had higher expectations of the contributions of ingroup members, and their own behavior was more strongly conditioned on other group members' expected behavior in the ingroup conditions. In ingroup contexts, subjects displayed a form of “strong reciprocity” by giving more than they expected others to at high expectation levels but less at low expectation levels. Once these interactions are taken into account, we do not find a direct effect of ingroup bias anymore. We discuss these results in the light of theories of cultural group selection and conclude that too much emphasis may have been laid on direct intergroup conflict. Our results suggest that differential cooperativeness, rather than parochialism, may characterize the behavior of individuals in cultural ingroups and outgroups.