Social Norm, Costly Punishment and the Evolution to Cooperation

Both laboratory and field evidence suggest that people tend to voluntarily incur costs to punish non-cooperators. While costly punishment typically reduces the average payoff as well as promotes cooperation. Why does the costly punishment evolve? We study the role of punishment in cooperation promotion within a two-level evolution framework of individual strategies and social norms. In a population with certain social norm, players update their strategies according to the payoff differences among different strategies. In a longer horizon, the evolution of social norm may be driven by the average payoffs of all members of the society. Norms differ in whether they allow or do not allow for the punishment action as part of strategies, and, for the former, they further differ in whether they encourage or do not encourage the punishment action. The strategy dynamics are articulated under different social norms. It is found that costly punishment does contribute to the evolution toward cooperation. Not only does the attraction basin of cooperative evolutionary stable state (CESS) become larger, but also the convergence speed to CESS is faster. These two properties are further enhanced if the punishment action is encouraged by the social norm. This model can be used to explain the widespread existence of costly punishment in human society.social norm; costly punishment; cooperative evolutionary stable state; attraction basin; convergence speed

Probabilistic sharing solves the problem of costly punishment

Cooperators that refuse to participate in sanctioning defectors create the second-order free-rider problem. Such cooperators will not be punished because they contribute to the public good, but they also eschew the costs associated with punishing defectors. Altruistic punishers - those that cooperate and punish - are at a disadvantage, and it is puzzling how such behaviour has evolved. We show that sharing the responsibility to sanction defectors rather than relying on certain individuals to do so permanently can solve the problem of costly punishment. Inspired by the fact that humans have strong but also emotional tendencies for fair play, we consider probabilistic sanctioning as the simplest way of distributing the duty. In well-mixed populations the public goods game is transformed into a coordination game with full cooperation and defection as the two stable equilibria, while in structured populations pattern formation supports additional counterintuitive solutions that are reminiscent of Parrondo's paradox.Comment: 15 pages, 5 figures; accepted for publication in New Journal of Physic

Costly Punishment Across Human Societies

Recent behavioral experiments aimed at understanding the evolutionary foundations of human cooperation have suggested that a willingness to engage in costly punishment, even in one-shot situations, may be part of human psychology and a key element in understanding our sociality. However, because most experiments have been confined to students in industrialized societies, generalizations of these insights to the species have necessarily been tentative. Here, experimental results from 15 diverse populations show that (i) all populations demonstrate some willingness to administer costly punishment as unequal behavior increases, (ii) the magnitude of this punishment varies substantially across populations, and (iii) costly punishment positively covaries with altruistic behavior across populations. These findings are consistent with models of the gene-culture coevolution of human altruism and further sharpen what any theory of human cooperation needs to explain

Emotion expression in human punishment behavior

Evolutionary theory reveals that punishment is effective in promoting cooperation and maintaining social norms. Although it is accepted that emotions are connected to punishment decisions, there remains substantial debate over why humans use costly punishment. Here we show experimentally that constraints on emotion expression can increase the use of costly punishment. We report data from Ultimatum Games11, where a proposer offers a division of a sum of money and a responder decides whether to accept the split, or reject and leave both players with nothing. Compared to the treatment where expressing emotions directly to proposers is prohibited, rejection of unfair offers is significantly less frequent when responders can convey their feelings to the proposer concurrently with their decisions. These data support the view that costly punishment might itself be used to express negative emotions, and suggest that future studies will benefit by recognizing that human demand for emotion expression can have significant behavioral consequences in social environments including families, courts, companies and markets.ultimatum game, emotion expression, sanctions, cooperation

Imperfect public monitoring with costly punishment - An experimental study

This paper experimentally investigates the effects of a costly punishment option on cooperation and social welfare in long finitely repeated public good contribution games. In a perfect monitoring environment increasing the severity of the potential punishment monotonically increases both contributions and the average net payoffs of subjects. In a more realistic imperfect monitoring environment, we find a U-shaped relationship between the severity of punishment and average net payoffs. Access to a standard punishment technology in this setting significantly decreases net payoffs, even in the long run. Access to a very severe punishment technology leads to roughly the same payoffs as with no punishment option, as the benefits of increased cooperation offset the social costs of punishing.public good contribution experiments; imperfect monitoring; welfare implications of costly punishment

Punishment, Inequality and Emotions

Cooperation among people who are not related to each other is sustained by the availability of punishment devices which help enforce social norms (Fehr and Gächter, 2002). However, the rationale for costly punishment remains unclear. This paper reports the results of an experiment investigating inequality aversion and negative emotions as possible determinants of punishment. We compare two treatments of a public good game, one in which costly punishment reduces the immediate payoff inequality between the punisher and the target, and one in which it does not affect inequality. We show that while inequality-aversion prevents some subjects from punishing in the equal cost treatment, negative emotions are the primary motive for punishment. Results also indicate that the intensity of punishment increases with the level of inequality, and reduces earnings inequality over time.inequality aversion; negative emotions; free-riding; cooperation; experiment

Punishment, Inequality and Emotions

Cooperation among people who are not related to each other is sustained by the availability of punishment devices which help enforce social norms (Fehr and Gächter, 2002). However, the rationale for costly punishment remains unclear. This paper reports the results of an experiment investigating inequality aversion and negative emotions as possible determinants of punishment. We compare two treatments of a public good game, one in which costly punishment reduces the immediate payoff inequality between the punisher and the target, and one in which it does not affect inequality. We show that while inequality-aversion prevents some subjects from punishing in the equal cost treatment, negative emotions are the primary motive for punishment. Results also indicate that the intensity of punishment increases with the level of inequality, and reduces earnings inequality over time.cooperation ; experiment ; Free-Riding ; inequity aversion ; negative emotions