集団間状況の顕現性と実在集団における内集団協力の心理メカニズム

抄録

The present study investigated the replicability of a series of Nakagawa et al.’s research. The findings in the previous studies showed ingroup cooperation based on the Social Identity Theory (SIT) and the Bounded Generalized Reciprocity hypothesis (BGR). The cost of cooperation can moderate the relationship between ingroup collaboration and the expectation of reciprocity. However, none of the studies explicitly addressed outgroup members. Consequently, these studies are limited in SIT validity. Research should investigate whether people become more cooperative within an ingroup versus an outgroup. Therefore, we measured ingroup cooperation using the vignette study of Nakagawa et al. (2015). We added an outgroup member version to maintain the salience of the intergroup situation. Our results reproduce Nakagawa et al.’s research and show that cooperation within an ingroup is more significant than that with an outgroup, based on the generated psychological mechanisms of both theories.