Intergroup cooperation in the United States and Japan: Revisiting Yuki's (2003) theory on the cultural difference in the conceptualization of group boundaries

Social identity theory posits that individuals perceive the in-group as a homogenous entity comprised of depersonalized individuals, and this theory has provided a foundation to understand intergroup processes for many years. Cross-cultural research has suggested social identity theory may not apply to East Asians, who conceptualize their in-groups differently than those in from Western cultures. Specifically, Yuki and colleagues contend that East Asians perceive in-groups as networks wherein each individual is connected through personal ties, rather than homogenous entity comprised of depersonalized individuals. Furthermore, prior research has shown that East Asians are more likely to trust out-group members with potential personal connections, similarly to how they trust actual in-group members. This reflects their group boundary perception based on personal linkages rather than categorical membership. Conversely, individuals from Western cultures tend to trust in-group members more than out-group members, regardless of potential personal connections. Our preregistered study (N = 332 Japanese and 345 American university students) aimed to conceptually replicate key findings that support Yuki's account and expand upon the theory in the context of intergroup cooperation. Overall, we failed to find evidence for the network-based and category-based cooperation and trust among Japanese and Americans, respectively. Consequently, our results highlight the need for further experimental investigation and validation of Yuki and colleagues' theoretical framework.