The bystander effect delineates the impact of the presence of others on an person's perception of and response to a situation.
The term bystander effect, or bystander apathy, was first used by psychologists in the early 1960s. The 1964 murder of New Yorker Kitty Genovese provides a graphic illustration of this phenomenon. Genovese was attacked outside her apartment building. She screamed for help but while some individuals heard her no one came to her aid. After the attack, one person called the police. Genovese died in an ambulance en route to the hospital. Researchers have distinguished several components of the bystander effect. First, witnesses must perceive the situation as an emergency. When others are present and do not take action or behave as if nothing were wrong, most observers will tend to interpret the situation as a nonemergency. Psychologists describe this as pluralistic ignorance. The perceptions and beliefs of the group led each individual to be lulled into inaction. In the case of Genovese's murder, her neighbors did not interpret her cries for help as a group. Each person, isolated in his or her own apartment, heard the disturbance and had no way of knowing the reactions of others who were hearing Genovese's screams. Each individual could choose to believe that someone else was taking action; therefore, the responsibility for action fell to that imagined other neighbor. Psychologists use the term diffusion of responsibility to describe this reaction.
Experiments have been developed to demonstrate the components of the bystander effect. In one experiment, designed to test the power of pluralistic ignorance, male subjects were given appointments for an interview. As they waited in an outer room, smoke began to pour through a ventilation duct. Researchers observed the subjects through a one-way mirror for three minutes. Seventy-five percent of the subjects who were alone in the waiting room reported the smoke within two minutes, while 13% of those tested in groups reported the smoke. Those who did not report the smoke explained that, since others in the room did not seem to be concerned, the smoke must have been air conditioning vapors or steam. This experiment illustrates that bystanders contribute significantly to an individual's interpretation of a situation.
See also Approach versus avoidance ; Attitude and behavior ; Attribution theory ; Conformity .
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