Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Case studies of cartels and recent theory suggest that communication is a key factor for cooperation under imperfect monitoring, where actions can only be observed with noise. We conduct a laboratory experiment to study how communication affects cooperation under different monitoring structures. Pre-play communication reduces strategic uncertainty and facilitates very high cooperation rates at the beginning of an interaction. Under perfect monitoring, this is sufficient to reach a high and stable cooperation rate. However, repeated communication is important to maintain a high level of cooperation under imperfect monitoring, where players face additional uncertainty about the history of play.