Acting without considering personal costs signals trustworthiness in helpers but not punishers

Third-party punishment and helping can signal trustworthiness, but the interpretation of deliberation may vary: uncalculated help signals trustworthiness, but this may not hold for punishment. Using online experiments, we measured how deliberation over personal costs and impacts to targets affected the trustworthiness of helpers and punishers. We expected that personal cost-checking punishers and helpers would be trusted less. Conversely, impact deliberation was expected to increase the perceived trustworthiness of punishers but not helpers. Replicating previous work, we found that refraining from checking the personal cost of helping signals trustworthiness (although evidence for observers trusting uncalculating over calculating helpers was mixed). This did not extend to punishment: only uncalculating non-punishers were more trustworthy than cost-checking non-punishers. Impact deliberation results were mixed: deliberation affected the trust and trustworthiness of non-helpers more than helpers and no conclusive results were found for punishment. These results show that deliberation differentially affects assessments of those who help or punish others. The Stage 1 protocol for this Registered Report was accepted in principle on 13th November 2023. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.24559462.v1 . This Registered Report replicates the finding that not checking the personal cost of helping signals trustworthiness. However, in a third-party punishment setup, avoidance of cost-checking only increased trustworthiness in those who also do not punish.