Peer punishment in teams: expressive or instrumental choice?

A key question about human societies is how social norms of cooperation are enforced. Subjects who violate norms are often targeted by their peers for punishment. One can interpret such peer punishment of norm violators as a second-order public good. In an experiment with small teams we examine whether subjects treat punishment itself as a public good. Results do not support this view and rather suggest a hard-wired taste for punishment; subjects are engaged in a cooperative task but ignore the public good characteristics of punishment