Coordination with Communication Under Oath

We study the simultaneous move version of a coordination game in which failures arise due to the use (and fear) of weakly dominated strategies. Existing evidence shows neither cheap talk communication between players nor historical information on past decisions nor even repetition based learning are able to implement the efficient outcome. We study the effect of one addition to the design: subjects sign a truth-telling oath before participating to the game with cheap-talk communication. We find oath significantly improves the truthfulness of messages sent, as well as helps eliminating weakly dominated actions. This change however has very few consequences on coordination, because receivers do not adjust their own strategies for this change