Taking turns

Two individuals face a regular task that requires the effort of only one. They take turns but sometimes arrange to swap obligations. These swaps account for their changing, private costs. While seemingly primitive, flexible turn-taking is surprisingly efficient, even relative to what can be achieved by mechanisms using monetary transfers. I model and experimentally evaluate a simple form of flexible turn-taking and then present a second form that is both consistent with patterns of subject behavior and approximately second-best in a benchmark case.