Charness and Dufwenberg (2006) find that promises increase cooperation and suggest that the behavior of subjects in their experiment is driven by guilt aversion. By modifying the procedures to include a double blind social distance protocol we test an alternative explanation that promise keeping...

Previous research has suggested that communication and especially promises increase cooperation in laboratory experiments. This has been taken as evidence for internal motivations such as guilt aversion or preference for promise keeping. The original goal of this paper was to examine promises...

Previous research has suggested that communication and especially promises in-crease cooperation in laboratory experiments. This has been taken as evidence for internal motivations such as guilt aversion or preference for promise keeping. The goals of this paper are to examine messages under a...