Norms and Contracting
通过实验室实验发现，契约能建立关系规范，偏离规范会带来负效用；包含不可执行的“握手”协议（约定最优行动）的简单契约往往最有效，尤其在战略互补博弈中，这解释了为何契约常是不完全的。
We argue that contracts establish the norms of a relationship and that individuals incur disutility when deviating from these norms. In a laboratory experiment, we allow agents to make simple contracts before they play one of four games, and the most effective contract always includes an unenforceable “handshake” agreement to take the first-best action. In three games, a contract with only this handshake agreement is (at least weakly) optimal. The handshake is particularly effective in games with strategic complements. Our results highlight an explanation for contractual incompleteness: establishing a norm can effectively substitute for weak enforceable restrictions. This paper was accepted by Brad Barber, Teck Ho, and Terrance Odean, special issue editors.