Dishonesty invites costly third-party punishment

Abstract Third-party punishment for norm violators is an evolvable enforcer of social norms. The present study, involving two experiments, examined whether violations of honesty norms would induce costly third-party punishments. In both experiments, participants in the third-party role observed a protocol of the trust game, in which the trustee solicited the trustor to transfer his/her endowment by stating that the trustee would return x units from the total resource. Dishonesty was defined such that the trustee in fact returned fewer than x units. Participants were asked about their willingness to incur some cost to reduce the trustee's payoff. In Experiment 1, x was exactly half of the total resource. Participants were willing to incur more cost to punish the dishonest trustee than the trustee who allocated the resource unequally but had not sent the dishonest message. In Experiment 2, x was more than half of the total resource and the dishonest trustee allocated the total resource equally. Therefore, the dishonest trustee was not unfair in Experiment 2. Approximately half of the participants (16 of 30) punished the dishonest but fair trustee, while few participants (1 of 30) punished the fair trustee who had not sent the dishonest message. These experiments together demonstrated that participants were willing to incur some cost to punish honesty-norm violators, even when the participants themselves were not harmed by the norm violation.