Abstract: Altruistic punishment means that individuals punish, although the punishment is costly for them and yields no material gain. Recent research found that penalizing rule-breakers activated a brain region called the dorsal striatum, which is involved in experiencing pleasure or satisfaction. And researchers suggested the outcome of altruistic punishment should be equivalent to the money rewards. At this point the researchers had discovered a correlation — that the pleasure-related brain activity occurred along with inflicting the punishment — but a deeper question remained: Did one experience cause the other? Further experiments indicated that inflicting the punishment didn’t cause the players to feel satisfaction. Instead, as they decided to impose the penalty, the players were anticipating feeling satisfied. Besides, these studies concerned the decision making, rather than the feedback outcome itself. Therefore, it is not clear how humans evaluate the outcome of altruistic punishment?
Study 1 using single trust game to ask the subjects to evaluate their emotions between the “the outcome before the punishment” and “the outcome after the punishment”, “ the outcome of cooperation” and “ the outcome of the altruistic punishment”, the “the outcome of the altruistic punishment” and “the outcome of the non-punishment” have found positive emotions increased and negative emotions weakened after the altruistic punishment compared to the outcome before the punishment. However, the pleasant feelings from the outcome of the altruistic punishment were still far below that from the outcome of the cooperation and higher than that of "the outcome of the non-punishment". And both outcome of altruistic punishment and non-punishment were biased negative emotions, and non-punishment lower ratings. The degree of negative emotions caused by “non-punishment” was greater than “punishment”.
Study 2 using event related brain potentials studied the evaluative processes in the brain when subjects perceiving the outcome of “punish-other-lose” and “not punish-other-win”, “punish-self-lose” and “not punish-self-not lose” in the repeated trust game, and found the four kind of outcome generated remarkable feedback related negativity which was differentially sensitive to positive and negative feedback. Therefore, the results suggested that subjects evaluate the outcome of altruistic punishment as negative feedback, and the FRN amplitudes of “not punish-other-win” and “not punish-self-not lose” were larger separately than that of “punish-other-win” and “punish-other-lose”. That is, the FRN amplitudes of “not punish” which had a greater degree of negative emotions were larger than those of “punish” which had a smaller degree of negative emotions. These results suggested that the FRN reflected effective motivation process about social outcome.

Key words: feedback related negativity, altruistic punishment, emotion, outcome evaluation