A Game-Theoretic Exploration of the Bystander Effect

by Niene Tempelman, Hester van der Weij, & Evelien van Meeteren
2645 words



Literature Review


           The Effects of a Criminal Record
           The Effects of a Reward




Literature Review

            The bystander effect refers to the tendency of people to be less likely to help an individual in trouble when more people are present. This is explained by the principle of diffusion of responsibility, meaning that responsibility to help is divided and diluted between each witness, thereby decreasing the pressure for each individual to intervene (Thomas et al., 2016). Additionally, there are two other motives preventing people from helping. Firstly, there is “audience inhibition”, which is the fear that the situation transpires not to be an emergency, thus intervening would lead to embarrassment. Secondly, there is “social influence”, where witnesses screen the inaction of others and see this as cues to not intervene (Latané & Nida, 1981). 

            The predicament witnesses find themselves in can be explained as a social dilemma. Usually, a social dilemma is characterised by a dominant strategy and the resulting pure strategy Nash Equilibrium (NE), is a deficient equilibrium (Dawes, 1973). A dominant strategy is the strategy which is optimal for the player regardless of what the other player chooses. A NE is present when no player - after choosing their strategy - can enhance their expected payoff by altering their strategy when the other players do not change their strategy. A pure strategy NE occurs when the dominant strategy is chosen for sure, and not on a probability distribution. To overcome this social dilemma and attain a more efficient outcome, individuals must cooperate instead of playing their dominant strategy.

            However, in the case of Catherine Genovese, there is no dominant strategy, resulting in two mixed strategy Nash equilibria, meaning a negative coordination where one of the players sacrifices themselves is needed. As Diekmann (1985) described, this is caused by the incentive for “free-riding” of someone else helping being bigger than the incentive to increase the collective good by helping the victim at the cost of the volunteer. However, if no one intervenes, all players lose. This is explained as the Volunteer’s Dilemma (VD), leading to the bystander effect.

            As this social dilemma can be presented in a strategic way, game theory can help explain the tendency that when more people are present the probability of intervention decreases. Furthermore, game theory will help to give insights into the effects of introducing punishments and/or rewards into the payoff structure and if these changes result in increased incentive to overcome the bystander effect.

            Rewards and punishments can be proposed as a solution for this social dilemma, as  they are ways to make acting more attractive or not acting less attractive (van Lange, Rockenbach & Yamagishi, 2014). Although laws regarding people’s duty to help in life-threatening situations do exist, for instance, in the Netherlands, usually these laws only apply in some rare cases and there are not many known cases of people actually being punished for their lack of action (Art. 450 Wetboek van Strafrecht, 1984). Rewards and punishments can be both tangible and intangible, meaning that a reward can, for example, be in the form of money or in the form of positive media attention. Similarly, a punishment could be a fine or negative media attention. Many researchers have claimed that intangible rewards and punishments can be effective in societies with strong social norms regarding helping others, which is the case in more collectivist countries such as China and Japan (Chekroun & Brauer, 2002).