We run several experiments which allow us to compare cooperation under perfect and imperfect information and under a centralized and decentralized punishment regime. We nd that (1) centralization by itself does not improve cooperation and welfare compared to an informal, peer-to-peer punishment...

In three party ultimatum games the proposer can first decide whether to exclude one responder, what increases the available pie. The experiments control for intentionality of exclusion and veto power of the third party. We do not find evidence for indirect reciprocity of the remaining responder...