Darley and Latané bystander intervention 1968
Participants who believed more people could also hear a staged emergency were less likely to respond, and slower to do so.
Main paper: Darley, J. M., & Latané, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility. Journal of Personality and Social Psychology, 8(4), 377–383.
The question
Does the number of people who could help change whether any one person helps?
Design: experiment
The researchers set the conditions and compare outcomes between or within groups. Each profile says whether participants were randomly assigned.
The researchers varied how many other listeners participants believed were present. The manipulated variable was perceived group size; other listeners were not physically present.
Participant and victim only
- Hear a seizure over the intercom
Result reportedMore likely and quicker to report
Added listeners
- Believe others also hear it
Result reportedLess likely and slower to report
Original diagram drawn for this site from the descriptions in the sources. It is a simplified summary, not a figure from the paper.
Procedure
Each participant sat alone with headphones and a microphone for what appeared to be an intercom discussion. Prerecorded voices simulated the other discussants, including a speaker who appeared to have a seizure. Participants believed either that only they and the victim were involved or that additional listeners were present.
Researchers measured whether and how quickly the participant left to report the emergency. Participants could not see the other listeners or ask what they were doing.
Findings
The more bystanders participants believed were present, the less likely and the slower they were to report the emergency. Personality and background measures did not reliably predict who helped.
Interpretation
The comparison supports diffusion of responsibility: believing others could respond reduced individual reporting. It did not test copying visible bystanders, because their behavior was unavailable.
Limits on what it shows
- The emergency was staged, and participants could not see each other, which differs from many real emergencies.
- Student participants in a single study with a small number of conditions do not map directly onto community settings.
- The study cannot say how the effect changes when an emergency is clearly dangerous or when bystanders can see each other.
Ethics
Participants believed a person was in serious distress and were deceived about the situation. The risks were distress during the session and guilt afterward, which makes a careful debriefing essential.
Replication and reassessment
The original article invokes a widely repeated account of the 1964 Kitty Genovese killing. The textbook notes problems with that story. Evaluate the recorded-emergency comparison on its design and evidence, rather than treating the anecdote as independent confirmation.
Think it through. An original practice question written for this site.
Why was it useful to prevent participants from seeing whether the other listeners were helping?
Show a way to reason about it
It separated the believed presence of other listeners from observing their actions. A slower response could not simply be copying visible inaction. The inference still concerns reporting a staged emergency, not every form of helping.
Nothing you think or select here is recorded.
Textbook connection
Covered in this sectionOpenStax Psychology 2e, 12.6 Aggression
Section discusses the bystander effect in general terms.
Sources and access scope
Each label says how much of the source was opened while preparing this profile. An unopened source is listed so the claim can be checked, not because it was read.
- Darley and Latané (1968), original article. (n.d.). https://www.ucdenver.edu/docs/librariesprovider102/default-document-library/bystander-intervention-john-darley-and-bibb-latane.pdfOriginal researchSelected full-text sections inspected
Selected method, abstract and discussion passages inspected. Other discussants and the seizure were prerecorded; the participant could not observe other listeners responding.
- Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020). Psychology 2e. OpenStax. https://openstax.org/books/psychology-2e/pages/12-6-aggressionTextbook contextSelected textbook passages inspected
Textbook context. The section discusses the bystander effect in general terms and notes the inaccurate details of the 1964 case.