Stanford prison simulation 1973
A staged prison at Stanford ended early after volunteers playing guards and prisoners behaved harshly and with distress. A 2019 archival study argues that the guards were instructed and that the roles did not simply emerge.
Main paper: Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a simulated prison. International Journal of Criminology and Penology, 1, 69–97.
The question
Does placing people in a role by itself cause cruelty, or did the setup guide what they did?
Design: simulation
A staged situation meant to resemble a real setting. What it shows about real settings depends on how closely the staging matches them.
A staged prison with no comparison condition, run in 1971 and published in 1973, with the experimenters acting as superintendent and staff. It is a contested simulation, not causal proof that roles produce the same behavior in everyone.
Guards (volunteers)
- Assigned to the role, as reported
- Given instructions about the role
Result reportedSome behaved harshly
Prisoners (volunteers)
- Assigned to the role, as reported
- Held in the mock prison
Result reportedDistress; study ended early
Experimenters
- Acted as staff and superintendent
Result reportedShaped the setting, per the critique
Original diagram drawn for this site from the descriptions in the sources. It is a simplified summary, not a figure from the paper.
Procedure
The authors report that volunteer male college students were randomly assigned to be guards or prisoners in a mock prison in a Stanford building in 1971. The simulation ran for nearly a week. The researchers took roles in the prison hierarchy, with Zimbardo as superintendent. Observations, recordings and tests were gathered by the research team.
The research team recorded observations, questionnaires, interviews and behavior. Randomly allocating prison roles did not supply a comparison prison with different instructions or an independent research team.
Findings
The authors reported that the simulated prison became psychologically compelling. They described prisoners as passive, dependent and depressed, and guards as gaining power and group identification.
Le Texier (2019) used archival materials and 15 interviews. He reports that guards were given instructions about how to behave, that participants may have been responding to demand characteristics, and that the archive is incomplete.
Interpretation
The original authors read the results as showing the power of a situation and its roles. The critique reads them as showing how experimenters' expectations and instructions can shape behavior, which limits what the study says about roles themselves.
Limits on what it shows
- No comparison condition, so the study cannot show what behavior would have occurred under different instructions.
- Experimenters took part in running the prison, so their expectations and instructions may have influenced guards and prisoners.
- Participants knew it was a study and were self-selected volunteers, which raises demand characteristics. These are limits on inference, not minor details.
Ethics
Participants experienced humiliation and distress, and the simulation ended earlier than planned. It is a standard case in discussions of harm to participants and of researchers who hold a role inside their own study.
Replication and reassessment
Le Texier (2019), in American Psychologist, argues from archival evidence that the study should not be taken as showing that ordinary people become cruel simply by taking a role. The original authors published a response in 2020. Treat the simulation as a contested demonstration of how a staged setup can shape behavior, not as causal proof of universal role effects.
Think it through. An original practice question written for this site.
If experimenters told guards what kind of behavior was expected, what can the study still tell us, and what can it no longer tell us?
Show a way to reason about it
It can tell us that a setting with strong cues and authority can lead volunteers to act in harsh ways, and it can illustrate research ethics problems. It cannot show that taking a role alone produces cruelty, because the instructions are a competing explanation.
Nothing you think or select here is recorded.
Textbook connection
Covered in this sectionOpenStax Psychology 2e, 12.2 Self-presentation
Section presents the Stanford study and a critique.
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.
- Haney, banks and zimbardo, report archived by the office of justice programs. (n.d.). https://www.ojp.gov/pdffiles1/Photocopy/10301NCJRS.pdfOriginal researchSelected full-text sections inspected
Selected abstract and method passages inspected in an archived report version. The main citation identifies the 1973 journal publication; this file is not treated as verification of every journal page.
- Le Texier, T. (2019). Debunking the Stanford prison experiment. The American Psychologist, 74(7), 823–839. https://doi.org/10.1037/amp0000401Consulted sourceReassessment or critiqueAbstract inspected
Abstract inspected with page tools. It reports archival research and 15 interviews, guard instructions, demand characteristics and incomplete data. The full article has not been inspected.
- Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020). Psychology 2e. OpenStax. https://openstax.org/books/psychology-2e/pages/12-2-self-presentationTextbook contextSelected textbook passages inspected
Textbook context. The section presents the Stanford study and includes a critique.
- Zimbardo, P. G., & Haney, C. (2020). Continuing to acknowledge the power of dehumanizing environments: Comment on haslam et al. (2019) and le texier (2019). The American Psychologist, 75(3), 400–402. https://doi.org/10.1037/amp0000593Consulted sourceReassessment or critiqueAbstract inspected
The abstract and bibliographic record were inspected to establish the authors' response and its date. The full comment was not inspected.