Does similarity trigger cooperation? Dyadic effect of similarity in social value orientation and cognitive resources on cooperation

Although a considerable amount of research has demonstrated a robust relationship between social value orientation and cooperation, these studies may be limited by focusing solely on the individual. Building on the growing literature documenting the effect of group formation on cooperation and personality similarity on negotiation, the present study explored whether similarity in social value orientation (both being pro-social or pro-self) leads to more cooperation in social dilemmas among dyad members. Drawing from expectancy theory and the concept of cognitive resources, we further predicted that the relationship between similarity in social value orientation and cooperation uniquely depends on whether the individual is cognitively busy. To test our hypothesis, we grouped our participants according to their social value orientation into three different dyads (similar-pro-self, similar-pro-social, and pro-self-pro-social) to complete a repeated prisoner’s dilemma task, and controlled their cognitive resources using a simultaneous digit memory task. The results suggested that (1) heterogeneous dyads’ (pro-self-pro-social) cooperation possibility experience a steeper decay as the number of rounds increases compared with the two homogeneous dyads (similar-pro-self, similar-pro-social). In addition, (2) similarity in social value orientation, interacting with participants’ cognitive resources, significantly influenced individual-level cooperation. Specifically, both pro-selfs and pro-socials, paired with unlike-minded counterparts, were more cooperative when they had abundant cognitive resources. However, cognitive resources had no significant influence on dyads with similar social value orientation. Overall, these findings demonstrate the importance of considering personality configuration when attempting to understand cooperation in social dilemmas among dyads.