Bystander Behaviour and Piliavin's Subway Study
What Is the Bystander Effect?
Imagine someone collapses on a crowded train. Surely with so many people around, someone will help — right? Psychologists have found the opposite is often true. The bystander effect is the finding that a person is less likely to receive help when many witnesses are present than when only one witness is there. The main explanation for this is diffusion of responsibility — each bystander assumes someone else will act, so no one does.
Psychologists group the factors that affect whether a bystander intervenes into two categories: situational factors and personal factors.
Situational Factors Affecting Bystander Intervention
The presence of other bystanders reduces the likelihood of intervention through diffusion of responsibility. When many people are watching, each individual feels less personally responsible for helping, because everyone assumes someone else will take action. People also look to others to judge whether a situation is really an emergency — if nobody else looks alarmed, bystanders assume nothing is wrong.
Bystanders weigh the cost of helping against the cost of not helping. High costs — personal danger, lost time, embarrassment, effort — reduce intervention. Low costs increase the chance someone will step in. Calling emergency services is low-cost and more likely to happen than physically restraining a dangerous person.
Personal Factors Affecting Bystander Intervention
Personal factors are characteristics of the individual bystander that make them more or less likely to help.
Similarity to the victim is one key personal factor. Bystanders are more likely to help someone who is similar to themselves, for example someone of the same race, age group or social background. Perceived similarity creates empathy and a sense of shared identity, which makes walking away feel worse.
Expertise is the other key personal factor. Someone with relevant skills — a trained first-aider, nurse or police officer — is more likely to intervene because they feel competent to help. Without expertise, a bystander may worry that helping could make things worse, which increases the perceived cost of intervening.
Situational factors reducing intervention include the presence of others (diffusion of responsibility) and a high cost of helping. Personal factors increasing intervention include similarity to the victim and relevant expertise.
Piliavin's Subway Study
Piliavin et al. (1969) carried out a field experiment to investigate bystander behaviour in a real-life setting, using the victim's appearance to test whether cost and similarity affect helping.
Aim: to investigate the effect of victim characteristics on bystander behaviour in a naturalistic environment.
Procedure: the study took place on the New York subway. A confederate collapsed in a train carriage. In some trials the victim appeared drunk, carrying a bottle in a brown paper bag and smelling of alcohol; in others the victim appeared ill, carrying a black walking cane. Researchers recorded how quickly and how often passengers helped, and the race of the helper compared with the victim.
Results: the ill victim received help in around 95% of trials, and usually very quickly (typically within seconds). The drunk victim received help in around 50% of trials. Race had little effect on helping overall; a tendency for same-race helping appeared mainly when the victim appeared drunk. The longer a trial went on without help, the more likely other passengers were to leave the carriage rather than assist.
Conclusion: bystanders make a cost–benefit calculation. They are more willing to help when the perceived cost is low (an ill victim is not seen as dangerous) and when they perceive similarity to the victim. Piliavin concluded that both victim characteristics and perceived cost shape whether a bystander intervenes.
In Piliavin's subway study, race had little effect on helping overall, with a slight same-race tendency only when the victim appeared drunk; the ill victim was helped faster and more often (about 95%) than the drunk victim (about 50%), supporting the role of cost.
Evaluating Piliavin's Study
A strength of Piliavin's study is its high ecological validity. Because it took place on a real subway with genuine passengers who did not know they were being studied, the findings reflect authentic behaviour rather than behaviour produced for an experiment. This is a real advantage over laboratory studies of helping.
However, the study raises ethical concerns. Passengers did not give informed consent, could not exercise their right to withdraw, and may have found watching someone collapse distressing. Deliberately creating a distressing scene in public without consent would not meet current ethical standards. The study is also limited to one city and transport setting, which may reduce how far the findings generalise to other emergencies or cultures.
This research has practical value too. Knowing that diffusion of responsibility reduces helping, safety campaigns can tell bystanders directly that they personally should act, rather than assuming someone else will. Emphasising shared community identity between potential helpers and those in need may also raise the chance that help is offered.