THE EFFECT OF REINFORCEMENT DELAY AVOIDANCE ON HUMAN INEQUITY DECISIONS IN A MINI-ULTIMATUM GAME

When offered an inequitable money distribution from a proposer, the responder tends to reject the proposal, denying money to both. This primacy of punishing inequity over maximizing income did not appear in Jensen, Call and Tomasello's (2007) adaptation of this game to apes. Unlike humans, ape responders tended to accept inequitable distributions, thereby maximizing reward. This report adapts their ape procedure to humans. Over trials, the proposer offered a responder equitable or inequitable distributions of dimes. When responder rejection required one minute of inaction, responders tended to reject inequity. When rejection required three minutes of inaction, they tended to accept inequitable distributions. For the three-minute group, the number of rejections during the last five trials significantly exceeded those in the first five. These results show that humans will maximize if the cost of punishment is too high, and that the tendency to punish extinguishes over a session.