We elicit human conditional punishment types by conducting experiments. We find that their punishment decisions to an individual are on average significantly positively proportional to other members’ punishment decisions to that individual.

Kocher et al. (2008) find that conditional willingness to contribute to a public good is considerably stronger at a U.S. research site, Appalachian State University, than at sites in Europe and Asia. I find that the willingness at Brown University, in Rhode Island, is not significantly different...

Exogenously imposed infinite repetition is known to mitigate people's uncooperative behaviors in dilemma situations with partner matching through personal enforcement. One as yet unanswered question is whether people collectively choose to interact with each other under the partner matching...