Home > Encyclopedia of Psychology > Bystander Effect

The effect of the presence of others on an individual's perception of and response to a situation.

The term bystander effect, or bystander apathy, was first employed by psychologists in the early 1960s. The 1964 murder of New Yorker Kitty Genovese provides an illustration of this phenomenon. Genovese, who was being savagely attacked outside her apartment building, screamed for help for over 30 minutes. Although 40 neighbors heard Genovese's desperate cries, no one came to her aid or even called the police. Researchers have explained several components of the bystander effect. First, witnesses must perceive the situation as an emergency. When others are present, not taking action or behaving as if nothing were wrong, all observers tend to view the situation as a nonemergency. Psychologists describe this as pluralistic ignorance, in which the behavior of the group causes each individual to be...