Prosocial behaviour and the bystander effect: WACE Year 12 Psychology Unit 4
“Explain prosocial behaviour and the bystander effect, including the factors that increase or decrease helping, with reference to Latane and Darley”
Prosocial behaviour is acting to benefit others, and altruism is helping with no expectation of reward; the bystander effect is the finding that people are less likely to help as the number of bystanders increases, explained by diffusion of responsibility and pluralistic ignorance, as Latane and Darley demonstrated through their five-step decision model.
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Prosocial behaviour and the bystander effect are not part of the SCSA Psychology ATAR Year 12 syllabus (Units 3 and 4, taught since 2024), so this page is not examined in the WACE Psychology ATAR exam. Both, including Latane and Darley (1968), are now in the Year 11 syllabus (Unit 2: Attitudes, stereotypes and social influence). The nearest Year 12 content is observational learning.
What this dot point is asking
SCSA asks you to define prosocial behaviour and altruism, explain the bystander effect and its causes, describe Latane and Darley's research and decision model, and list the factors that raise or lower helping. The marked skill is naming the step at which helping breaks down.
Prosocial behaviour and altruism
Prosocial behaviour is any action intended to benefit another person, such as helping, sharing, comforting or cooperating. Altruism is a specific form of prosocial behaviour: helping motivated by concern for others with no expectation of personal reward. Prosocial behaviour can be encouraged by empathy, social norms (the norm of reciprocity, the norm of social responsibility) and learned through reinforcement and modelling.
The bystander effect
The bystander effect is the counterintuitive finding that an individual is less likely to help a victim when other people are present, and that helping decreases as the number of bystanders increases. It was studied after the widely reported case in which a woman was attacked while many neighbours apparently failed to intervene.
Two main processes explain it.
- Diffusion of responsibility: when others are present, each person feels less personal responsibility to act, assuming someone else will.
- Pluralistic ignorance: in an ambiguous situation, people look to others to judge whether it is an emergency; if everyone appears calm, each concludes nothing is wrong.
Pluralistic ignorance occurs when individuals in a group privately doubt that a situation is normal but, seeing others act calmly, wrongly conclude that the group consensus is that there is no emergency. Everyone is reassured by everyone else's inaction, so no one helps.
Latane and Darley's decision model
Bibb Latane and John Darley proposed that helping depends on passing through five sequential steps, and failing any one stops help.
- Notice the event.
- Interpret it as an emergency (where pluralistic ignorance can block help).
- Take personal responsibility (where diffusion of responsibility can block help).
- Decide how to help (knowing what to do).
- Provide help (which may be blocked by fear or cost).
Their experiments supported this. In one, participants who believed they were the only witness to a staged seizure helped far more often and faster than those who believed several others were also present, confirming diffusion of responsibility.
The core finding is that the probability and speed of any one person helping falls as the number of bystanders rises. This is the opposite of the intuition that a crowd makes help more likely.
Factors affecting helping
Helping increases when the bystander notices the event, sees it clearly as an emergency, feels responsible (for example as the only witness), has the competence to help, knows the victim or sees similarity, and when the perceived cost of helping is low. Helping decreases with more bystanders, ambiguity, high personal cost or danger, and time pressure.
A collapse on a busy train
A passenger slumps in a crowded carriage. Everyone notices (step one passes). Because no one else reacts, each passenger assumes it is not serious, so step two fails through pluralistic ignorance. Even those who suspect an emergency assume someone else will act, so step three fails through diffusion of responsibility.
A precise answer identifies the step at which helping breaks down rather than just saying people did not help.
Why this matters
Understanding the bystander effect informs first-aid and safety training, which teaches people to assign responsibility directly (pointing to one person and asking them to call for help) to overcome diffusion of responsibility. It also links back to group influence, since both rest on diffusion of responsibility.
- Confusing diffusion of responsibility and pluralistic ignorance
- Diffusion is feeling less responsible because others could act; pluralistic ignorance is misreading the situation as non-emergency because others look calm.
- Saying crowds always help
- The bystander effect shows the opposite: more bystanders generally mean less help.
- Skipping the decision model
- A complete answer uses Latane and Darley's five steps and names which step fails.
- Equating prosocial behaviour with altruism
- Altruism is prosocial behaviour with no expectation of reward; not all helping is altruistic.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Original6 marksExplain the bystander effect, and describe how diffusion of responsibility and pluralistic ignorance each contribute to it.Show worked answer →
A 6 mark response needs the effect plus the two mechanisms explained.
- Bystander effect
- People are less likely to help a victim when others are present, and helping decreases as the number of bystanders increases, the opposite of the intuition that a crowd makes help more likely.
- Diffusion of responsibility
- When others are present, each person feels less personal responsibility to act, assuming someone else will, so no one helps.
- Pluralistic ignorance
- In an ambiguous situation, people look to others to judge whether it is an emergency; if everyone appears calm, each concludes nothing is wrong, and the group's inaction reassures everyone.
Markers reward the definition of the effect and the two distinct mechanisms, ideally noting that diffusion is about responsibility while pluralistic ignorance is about interpreting the situation.
Original7 marksDescribe Latane and Darley's decision model of helping, and use it to explain why a person might not be helped in a crowded public place.Show worked answer →
A 7 mark extended response needs the five-step model applied to a crowd.
- Decision model
- Latane and Darley proposed that helping requires passing five sequential steps, and failing any one stops help: notice the event, interpret it as an emergency, take personal responsibility, decide how to help, and provide help.
- Where it breaks down
- In a crowd, everyone may notice a collapsed person (step one passes), but because no one else reacts, each assumes it is not serious, so step two fails through pluralistic ignorance. Even those who suspect an emergency assume someone else will act, so step three fails through diffusion of responsibility.
- Supporting evidence
- In their staged-seizure experiment, participants who believed they were the only witness helped far more often and faster than those who believed others were present.
- Conclusion
- Markers reward the five named steps, identifying which step fails and why, and citing the staged-seizure finding.