Ultimatum game

The ultimatum game is a popular experimental economics game in which two players interact to decide how to divide a sum of money, first described by Nobel laureate John Harsanyi in 1961. The first player, the proposer, proposes a division of the sum with the second player, the responder. The responder can either accept the proposed division or reject it. If the responder accepts, the money is split according to the proposal; if the responder rejects, neither player receives anything. Both players know in advance the rules of the game. The game is typically designed as a one-shot interaction to isolate immediate reactions to fairness, thereby minimizing the influence of potential future interactions. However, even within this one-shot context, participants' decision-making processes may implicitly involve considering the potential consequences of repeated interactions, due to the fact that humans have evolved within societies that interact repeatedly. This design is crucial for observing pure, unadulterated responses to the proposed division.