A mirror has no effect on giving in the dictator game

  • Yuki Niwa Graduate School of Engineering , Nagoya Institute of Technology
  • Kai Hiraishi Kokoro Research Center, Kyoto University
  • Ryo Oda Nagoya Institute of Technology
Keywords: altruism, dictator game, mirror, reciprocity, third-party punishment


Evolutionary studies on human altruism toward strangers have proposed two motivations as proximate mechanisms for this behavior. The first involves the positive motivations inherent in expecting that actors will benefit in the long term by building a good reputation even if they accrue immediate costs for their altruistic behavior. The second involves the negative motivations inherent in avoiding identification as a norm violator. The presence of a mirror has been reported to enhance self-consciousness and evoke negative affect in response to an observer’s eyes. We conducted the dictator game with and without a mirror. Participants were asked to complete a post-experiment questionnaire designed to investigate what they were thinking when they decided the amount of money to offer the recipient and to explore their perceptions of the experimental situation. Although the negative affect elicited by an observer’s eyes was stronger under the mirror condition, the presence of the mirror did not increase the amount of money offered in the game.

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