Over the past decades, there has been considerable interest in individual differences in cooperative behaviour and how these can be explained. Whereas the Honesty–Humility dimension from the HEXACO model of personality has been identified as a consistent predictor of cooperation, the underlying motivational mechanisms of this association have remained unclear—especially given the confound between the temptation to exploit others and the fear of being exploited as motivational drivers of defection in social dilemmas. In a reanalysis and a new experiment, we tease apart these mechanisms by manipulating the rank order of pay-offs in a symmetric two-person game paradigm, essentially implementing the classic prisoner's dilemma, stag hunt, and chicken games. Results revealed that Honesty–Humility predicted cooperation specifically in the games in which temptation was a potential motivator of defection, whereas it did not account for cooperation in those games in which only fear implied defection. Our findings thereby shed light on the underlying motivational mechanisms of the Honesty–Humility–cooperation link and, more generally, demonstrate how economic games can be used to disentangle such mechanisms.
