Why do people reject unintended inequity? Responders' rejection in a truncated ultimatum game

Rejection of an inequitable and yet unintended outcome in a truncated ultimatum game was examined in an experiment with 46 undergraduate students (27 men and 19 women) from a large national university in Japan. In an ultimatum game, one of two players, the proposer, makes an offer to divide a fixed-sum of money. The other player, the responder, decides whether to accept or reject the offer. When the responder rejects the proposer's offer, neither of the two players receives a reward. Previous work examining the behavior of participants in the truncated ultimatum game employed strategy method in their experimental design. We examined whether these previous findings would be replicated in an experimental design that did not use the strategy method and instead used the standard one-shot game. Seven out of 46 responders given an inequitable offer rejected it, replicating prior results with the strategy method. We further found that subjects who rejected an offer that was involuntary and yet inequitable did not over-attribute intentions to the proposer's involuntary behavior more strongly than did acceptors. These findings strongly suggest that aversion to inequity is the explanation for the subjects' rejection of the inequitable offer.