Distinguished Research Fellow of the Institute of Economics at Academia Sinica, and Jointly Appointed Professor in Public Finance, National Chengchi University Abstract Ultimatum game is a simple bargaining game. Although simple, it is important in theory and practice. Game theory gives a precise prediction regarding the bargaining outcome of the ultimatum game. However, this precise prediction receives an outright rejection from experimental data. What are the possible reasons for the observed deviation between theoretic prediction and experimental data? This paper surveys the relevant literature from a variety of fields, including behavioral economics, anthropology, and neuroscience.