Ill-Defined versus Precise Pre-Play Communication in the Traveler's Dilemma

This article reports results from an experiment comparing the effects of vague versus precise pre-play communication in a highly competitive two-player game with conflicting interests. In the classic Traveler's Dilemma, non-binding precise messages about intent of play are pure cheap talk. We conjecture that a form of imprecise pre-play communication whereby subjects can submit ill-defined messages may help foster cooperation because of their vagueness. Comparing behavior both across modes of communication and to a baseline case without communication, we find that cooperation is highest when players can communicate using precise numerical messages. When communication with ill-defined messages is allowed, then conditional on receiving a message, subjects act more cooperatively than when no message is received. However, overall, the ability to exchange ill-defined messages does not substantially improve cooperation.