Revealing Preferences for Fairness in Ultimatum Bargaining

Abstract

The ultimatum game has been the primary tool for studying bargaining behavior in recent years. However, not enough information is gathered in the ultimatum game to get a clear picture of respondersâ?? utility functions. We analyze a convex ultimatum game in which respondersâ?? can â??shrinkâ?� an offer as well as to accept or reject it. This allows us to observe enough about respondersâ?? preferences to estimate utility functions. We then successfully use data collected from convex ultimatum games to predict behavior in standard games. Our analysis reveals that rejections can be â??rationalizedâ?� with neo-classical preferences over own- and other-payoff that are convex, nonmonotonic, and regular. These findings present a precise benchmark for models of fairness and bargaining.