Prosocial Behaviour and the Bystander Effect

Prosocial behaviour refers to actions that benefit others, such as helping, sharing, cooperating, and comforting. One of the most important questions in social psychology is: Why do people sometimes help others and sometimes fail to help? The study of the bystander effect has revealed surprising findings about the social factors that influence helping behaviour.

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The Kitty Genovese Case (1964)

The study of bystander behaviour was partly inspired by the case of Kitty Genovese, a young woman who was attacked and murdered outside her apartment in New York City in 1964. Initial media reports (later disputed) claimed that 38 witnesses saw or heard the attack but none called the police until it was too late.

This case shocked the public and led psychologists Darley and Latané to investigate why bystanders sometimes fail to help.

Note: Later investigations have questioned the accuracy of the "38 witnesses" claim. The actual events were more complex, and some people did attempt to help or call police. However, the case was important because it inspired crucial research into bystander behaviour.

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The Bystander Effect

The bystander effect is the finding that people are less likely to help when other people are present. The more bystanders there are, the less likely any individual is to help.

Darley and Latané (1968)

Darley and Latané tested the bystander effect experimentally:

• Participants were placed in individual booths and told they were participating in a group discussion via intercom
• During the discussion, one participant (actually a confederate) appeared to have an epileptic seizure
• The key variable was the number of people the participant believed were also in the discussion

Number of Others Present	% Who Helped Within 6 Minutes
0 others (participant alone with victim)	85%
1 other	62%
4 others	31%

Key finding: The more people the participant believed were present, the less likely they were to help, and the longer they took to respond.

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Why Does the Bystander Effect Occur?

flowchart TB
    E["Emergency event<br/>occurs"] --> Q1{"Notice<br/>the event?"}
    Q1 -->|No| W1[Walk on / no help]
    Q1 -->|Yes| Q2{"Interpret as<br/>emergency?"}
    Q2 -->|No - others<br/>not reacting<br/>pluralistic ignorance| W2[No help]
    Q2 -->|Yes| Q3{"Take<br/>responsibility?"}
    Q3 -->|No - others present<br/>diffusion of<br/>responsibility| W3[No help]
    Q3 -->|Yes| Q4{"Know how<br/>to help?"}
    Q4 -->|No| W4[No help]
    Q4 -->|Yes| Q5{"Decide<br/>to act?<br/>evaluation<br/>apprehension"}
    Q5 -->|No| W5[No help]
    Q5 -->|Yes| H[HELP given]

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1. Diffusion of Responsibility

Diffusion of responsibility is the main explanation for the bystander effect. When multiple bystanders are present, each individual feels less personally responsible for helping because they assume that someone else will take action.

• With only one bystander: they feel 100% responsible
• With 10 bystanders: each person feels only 10% responsible

2. Pluralistic Ignorance

In an ambiguous situation, people look to others for cues about how to behave. If nobody else is reacting, each individual assumes the situation is not an emergency — even if it is. Everyone is looking to everyone else, and nobody acts.

3. Evaluation Apprehension

People may be reluctant to help because they are worried about being judged by others. They may fear looking foolish if they intervene and the situation turns out not to be an emergency.

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Piliavin's Subway Study (1969)

Piliavin, Rodin, and Piliavin (1969) conducted a field experiment on the New York subway to study helping behaviour in a real-world setting.

Method

• A confederate collapsed in a subway car approximately 70 seconds after the train left a station
• In one condition, the confederate appeared drunk (carrying a bottle and smelling of alcohol)
• In another condition, the confederate appeared ill (carrying a cane and appearing sober)
• Researchers observed whether passengers helped, how quickly, and how many helped

Results

Condition	% of Trials Where Help Was Given	Average Time to Help
Ill (cane)	95% — almost always helped	~5 seconds
Drunk	50% — helped about half the time	~109 seconds (much slower)

Key Findings

• Helping was much more common than expected — challenging the bystander effect in this context
• People were much more likely to help someone who appeared ill than someone who appeared drunk
• The number of bystanders did not reduce helping in this study — possibly because the emergency was unambiguous and passengers could not easily escape the situation
• Same-race helping was more likely in the drunk condition (but not in the ill condition)

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Factors Affecting Helping Behaviour

Factor	Effect
Number of bystanders	More bystanders = less helping (bystander effect)
Ambiguity	More ambiguous situations = less helping
Perceived responsibility	People who feel personally responsible are more likely to help
Perceived deserving	People are more likely to help those perceived as deserving (ill > drunk)
Similarity	People are more likely to help those who are similar to them
Danger	Higher perceived danger = less helping
Cost-benefit analysis	People weigh the costs (risk, time) against benefits (feeling good, saving a life)

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Evaluation

Strengths

• Darley and Latané's research clearly demonstrates the bystander effect in controlled conditions
• Piliavin's study has high ecological validity — conducted in a real-world setting with unsuspecting participants
• The research has practical applications — understanding the bystander effect can help design interventions to increase helping behaviour

Weaknesses

• Lab studies of the bystander effect may lack ecological validity
• Piliavin's field experiment raises ethical issues (no informed consent, deception, potential distress)
• The Kitty Genovese case (which inspired the research) has been shown to be inaccurately reported
• Cultural differences in helping behaviour are not fully accounted for

Exam Tip: Be clear about the difference between the bystander effect (people help less when others are present) and diffusion of responsibility (the explanation — each person feels less responsible). Use specific statistics from Darley and Latané and Piliavin.

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Key Points

• The bystander effect: people are less likely to help when others are present.
• Main explanation: diffusion of responsibility — each person feels less personally responsible.
• Darley and Latané (1968): 85% helped alone vs 31% with 4 others.
• Piliavin et al. (1969): 95% helped an ill person; 50% helped a drunk person on the subway.
• Factors affecting helping: number of bystanders, ambiguity, perceived deserving, similarity, danger.

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Worked study: Piliavin, Rodin & Piliavin (1969) — the subway Samaritan