- 著者
- Yamagishi Toshio Mifune Nobuhiro
- 出版者
- Elsevier Inc.
- 雑誌
- Evolution and Human Behavior (ISSN:10905138)
- 巻号頁・発行日
- vol.30, no.4, pp.229-237, 2009-07
- 被引用文献数
- 77
Men exhibit a stronger tendency to favor the in-group over the out-group than women. We examined if this male-specific "coalitional psychology" represents in-group love or out-group hatred. One hundred thirty-three college freshmen played a Prisoner's Dilemma Game with a member of their own group and a member of another group. Both groups consisted of same sex participants. An in-group bias -- cooperation at a higher level with the in-group than the out-group -- based on expectations of cooperation from the in-group was observed for both men and women. When such expectations were experimentally eliminated, women did not show any in-group bias whereas men still exhibited an in-group bias. The male-specific in-group bias in this condition was found to be a product of intra-group cooperation rather than inter-group competition. These findings suggest that the male-specific coalitional psychology catered more toward within-group solidarity than promotion of aggression against the out-group.
- 著者
- Shinada Mizuho Yamagishi Toshio
- 出版者
- Elsevier
- 雑誌
- Evolution and Human Behavior (ISSN:10905138)
- 巻号頁・発行日
- vol.28, no.5, pp.330-339, 2007-09
- 被引用文献数
- 59
Human cooperation in a large group of genetically unrelated people is an evolutionary puzzle. Despite its costly nature, cooperative behaviour is commonly found in all human societies, a fact that has interested researchers from a wide range of disciplines including biology, economics, and psychology to name a few. Many behavioural experiments have demonstrated that cooperation within a group can be sustained when free riders are punished. We argue that punishment has both a direct and an indirect effect in promoting cooperation. The direct effect of punishment alters the consequences of cooperation and defection in such a way as to make a rational person prefer cooperation. The indirect effect of punishment promotes cooperation among conditional cooperators by providing the condition necessary for their cooperation -- i.e., the expectation that other members will also cooperate. Here we present data from two one-shot, n-person Prisoner's Dilemma games, demonstrating that the indirect effect of punishment complements the direct effect to increase cooperation in the game. Further, we show that the direct and indirect effects are robust across two forms of punishment technology; either when the punishment is voluntarily provided by game players themselves or when it is exogenously provided by the experimenter.