The evolution of punishment toward norm-violators has been discussed for understanding a large-scale human cooperation. Recent studies showed that the presence of cues of surveillance makes people concern about their reputation and increase altruistic behavior. Recent study also suggests that explicit cues of observation affect punitive behavior. We examined whether both explicit (being observed by an experimenter) and implicit cues (drawing of stylized eyes) of observation enhance third-party punishment. The results of the experiments with Japanese participants showed that both type of cues of observation increased third-party punishment only among those who did not feel anger toward an unfair allocator. In contrast, the cues suppressed the punishment when participant felt stronger anger toward an allocator. Moderating effect of emotion is interpreted as a cultural norm of emotional expression. Our study suggests that we humans are endowed with the psychological system inducing third-party punishment in response to cues of being observed while its function may be moderated by cultural factors.
