Strategic signaling or emotional sanctioning? An experimental study of ex post communication in a repeated public goods game

Several experimental studies show that ex post communication mitigates opportunistic behavior in social dilemmas. The source of this effect, especially in a repeated interaction, is nonetheless still obscure. This study provides a novel empirical testbed for two channels by which ex post communication may affect behavior in a repeated public goods game. One is related to strategic signaling. The other involves emotions induced by others' expressed disapproval. The presence of ex post communication strongly fosters pro-social behavior. The data do not support the signaling hypothesis, favouring the emotion-based explanation instead.