Social incentives foster cooperation through guilt aversion: An effect that diminishes with primary psychopathic traits.

The association between primary psychopathic traits and non-cooperative behaviors is well-identified. There is a lack of studies on how to motivate cooperative behaviors in individuals with primary psychopathic traits. This study investigated the effects of monetary incentives and social incentives on promoting cooperation in healthy adults with varying primary psychopathic traits. Participants played a one-shot public goods game (PGG) with other anonymous players in three different contexts: a social incentives context where participants' decisions would be judged by others, a monetary incentives context where participants' decisions would result in winning or losing money depending on their contributions, and a control condition where no additional incentives were implemented. We found that, compared to the control condition, both monetary and social incentives significantly improved participants' contributions to the public project-an indicator of cooperative behavior. However, the association between higher primary psychopathic traits and less cooperation was only observed in the context of social incentives. Computational modeling further revealed that this effect can be explained by the diminishing guilt aversion when participants deliberately violated their inferred expectations of themselves from others' perspectives. This study found that social incentives can encourage cooperative behaviors in non-clinical psychopathy, and identified the mental processes navigating this effect.