A pinboard by
Fan Yang

Post-Doc, Yale University


My study examines whether we have a possibly evolved, early-emerging aversion to free riders

Our project seeks to examine a mechanism that solves an evolutionary question that puzzles biologists--how humans are capable of maintaining group-level cooperation with unrelated strangers in evolution. Throughout history, our group life depends on members to contribute, but individuals have the incentive to free ride--to benefit from the group without making contributions. Therefore, humans must have evolved mechanisms to prevent free riding from happening in order for groups to survive. In this study, we examined whether humans have a possibly evolved, early-emerging aversion to free riders. We presented 4-5-year-old children with scenarios in which some individuals contribute to group goals whereas others free ride. We found that children this young strongly negatively evaluated and sanctioned the free riders. They were even willing to pay a cost to punish the free riders. Moreover, their negative responses to free riders were not based on the external outcomes the free riders caused to the group, but instead children intrinsically held the normative expectations that individuals are obligated to contribute to the group. Considering that children this age have limited experiences with groups and the systems that impose cooperation, the findings suggest that our ability to identify and sanction free riders may be an evolved tendency that constitutes a psychological machinery for cheater detection and punishment. Our negative reactions to free riders could deter free riding behaviors and may have served important evolutionary functions for maintaining cooperation within groups. Our findings thus provide strong evidence that the aversion to free riders could be a psychological mechanism that may help solve the evolutionary puzzle of cooperation.