Behavioural Differences and Neural Substrates of Altruistic and Spiteful Punishment

Toshio Yamagishi,Toko Kiyonari,Haruto Takagishi,Ryota Kanai,Alan S R Fermin,Masamichi Sakagami,Yang Li,Yoshie Matsumoto

doi:10.1038/s41598-017-15188-w

Abstract

Altruistic punishment following social norm violations promotes human cooperation. However, experimental evidence indicates that some forms of punishment are spiteful rather than altruistic. Using two types of punishment games and seven non-strategic games, we identified strong behavioural differences between altruistic and spiteful punishers. Altruistic punishers who rejected unfair offers in the ultimatum game and punished norm violators in the third-party punishment game behaved pro-socially in various non-strategic games. Spiteful punishers who rejected unfair offers in the ultimatum game but did not punish norm violators in the third-party punishment game behaved selfishly in non-strategic games. In addition, the left caudate nucleus was larger in spiteful punishers than in altruistic punishers. These findings are in contrast to the previous assumption that altruistic punishers derive pleasure from enforcement of fairness norms, and suggest that spiteful punishers derive pleasure from seeing the target experience negative consequences.

Highlights

In the present study, we proposed and successfully tested the hypothesis that altruistic punishers who exert costly punishment in the TPPG would behave pro-socially in non-strategic games, regardless of their behaviour in the UG, whereas spiteful punishers who reject unfair offers in the UG but do not exert costly punishment in the TPPG would behave selfishly in non-strategic games
Our results indicated that the two types of punishers differed in their behaviour and in grey matter volume (GMV) of the left caudate nucleus (CDn): Spiteful punishers exhibited a larger left CDn than altruistic punishers
In previous studies[6,7], activation of the dorsal striatum was observed in players who spent more money to deliver punishment to unfair players, suggesting that such attempts to punish are driven by the anticipation of pleasure following the enforcement of social norms and re-establishment of fairness

Summary

Introduction

We proposed and successfully tested the hypothesis that altruistic punishers who exert costly punishment in the TPPG would behave pro-socially in non-strategic games, regardless of their behaviour in the UG, whereas spiteful punishers who reject unfair offers in the UG but do not exert costly punishment in the TPPG would behave selfishly in non-strategic games This hypothesis is based on the previous finding that rejections of unfair offers in the UG do not necessarily reflect altruistic concerns for social norm enforcement[8,9,10,11,12]. These our findings support the conclusions derived from the behavioural experiment of the present study: Spiteful punishers anticipate pleasure from seeing their target suffer by rejecting unfair offers, while altruistic punishers reject unfair offers as a deliberate attempt to punish norm violators (as in the TPPG), rather than seeking pleasure from enforcing fairness norms

Methods

Results

Conclusion