Shared Identities and the Structure of Exchange Distinctly Shape Cooperation

Abstract

People frequently engage in preferential treatment toward those with whom they share category memberships. At the same time, sociologists have long understood that the structure of ongoing relations shapes micro-level interactions. Here, we ask whether-and if so, how-same-identity bias in cooperation interacts with key structural features of exchange relations. Specifically, we use the affect theory of social exchange (ATSE) to make predictions about cooperation in productive, reciprocal, and generalized exchange when people are embedded in networks where identities are either known and homogeneous, known and heterogenous, or unknown. Results from our experiment support both past work demonstrating same-identity bias in cooperation and the ATSE's predictions that productive exchange yields the highest levels of cooperation and affective attachment, followed by reciprocal and generalized exchange. More importantly, we find that shared identities and the structure of exchange are two orthogonal factors that distinctly promote cooperation in the presence of each other. Structures with known homogeneous identities are more cooperative and develop higher levels of affective attachment across all forms of exchange, and different types of exchange produce different levels of cooperation and affective attachment in line with the ATSE, but the identity and structural mechanisms do not interact. We conclude by discussing the theoretical implications of our findings for the ATSE and scholarship on social identity biases as well as the practical implications for facilitating cooperation in diverse groups.