Promises often foster trust and cooperation. A recent literature explores why. Two explanations have been proposed, and experimental tests provided some support and some controversy:- Charness & Dufwenberg (2006) (C&D) propose an expectation-based explanation (EBE). People are guilt averse (GA):...

Institutions for co-financing agreements often exist to encourage public good investment. Can such frameworks deliver maximal investment when agents are motivated by reciprocity? We demonstrate that indeed they can, but not in the way one might expect. If maximal investment is impossible in the...

We test whether promises per se are effective in enhancing cooperative behavior in a form of a trust game. In Charness & Dufwenberg (2006) we found considerable effectiveness for free-form personalized pre-play statements-of-intent ("promises"), in support of a theory of belief-dependent guilt...

We examine experimentally the impact of communication on trust and cooperation. Our design admits observation of promises, lies, and beliefs. The evidence is consistent with people striving to live up to others' expectations in order to avoid guilt, as can be modeled using psychological game...