Differential Cost-Benefit Estimation Stabilizes Cooperative Benefits of Commitment Signals

Communicating group commitment is critical for identifying reliable cooperative partners, and this assortment has been theorized to be facilitated by attaching costs to commitment signals. However, it remains unresolved why outsiders would not strategically fake such signals and then free-ride on the group’s public goods. We propose that the reliability of commitment signals is facilitated by differential computation of a signal’s costs and benefits, such that the cost-benefit trade-off favors signal production only for genuinely committed individuals. To test this, we conducted three preregistered studies (total N = 1,341; US general population) in which participants could choose to signal cooperative intent and then play a public goods game with other signalers (or non-signalers). We assessed how perceived costs and benefits of signaling varied across cooperative versus selfish strategies and modeled how these perceptions predicted signaling choices. Study 1 showed that cooperative individuals perceived greater cooperative benefits of signaling and preferentially assorted with one another, although selfish individuals who faked signals earned the most by free-riding. Study 2 used a real-world signal—religious text transcription—and demonstrated that highly costly religious signals deter outsiders, rendering religious cooperation profitable and resistant to free-riders, though not via differential perceptions of cooperative benefits. Finally, Study 3 revealed that committed members perceived religious signals as providing additional (i.e., not only cooperative) benefits that outsiders did not perceive, inadvertently stabilizing the cooperative function of religious signals. Together, these findings suggest that costly signals of group commitment persist because, while both cooperators and free-riders perceive cooperative benefits, the signaling trade-off is favorable only for those who also perceive additional benefits of signal production. Further and cross-cultural work is needed to establish the generality of this mechanism.