One of the outstanding results of three decades of laboratory market research is that under rather weak conditions prices and quantities in competitive experimental markets converge to the competitive equilibrium. Yet, the design of these experiments ruled out gift exchange or reciprocity...

We examine an Outside Option Game in which player I submits a claim for a share of a cake while player II simultaneously either makes a claim or chooses to opt out. If player II opts out, then she receives an opt-out payment while player I receives nothing. If player II opts in and if the claims...