"Beyond Two Player Interactions in Ultimatum Game"Krakovska, HanaThe Ultimatum Game has been a cornerstone in the study of fairness since its introduction in 1982 by Guth et al.. The game has a single round, a defined reward pool and two players with distinct roles: proposer and responder. The proposer proposes a division of the reward between the two players, while the responder can either accept or reject this split. Upon acceptance, the reward is divided accordingly, but rejection results in no reward for either player. In the subgame perfect Nash equilibrium the proposer offers the smallest unit of the reward and the responder accepts this split. However, this result is not found in experiments. People often reject low offers of 20-30% and proposers usually offer 30-50% of the reward. Since real-world situations often involve many people interacting simultaneously within a community, we are interested in this game beyond the simple two-player context. We define Multi-Responder-Multi-Proposer Ultimatum Game where multiple proposers and responders engage simultaneously in the splitting of the reward. This introduces competition among both proposers and responders. We derive Nash equilibria and evolutionarily stable strategies, as well as explore how the resultant non-trivial equilibrium offer levels and payoffs might inform the concept of fairness. |
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