In This Article Expand or collapse the "in this article" section Stanford Prison Experiment (SPE): Icon and Controversy

  • Introduction
  • Archival Sources
  • Primary Documentation of the SPE
  • Biographical Background
  • SPE and Related Experiments in Media
  • SPE in Textbooks, Handbooks, and Histories of Psychology
  • Replication of the SPE and Related Replications
  • Psychological Prison and Punishment Literature Related to the SPE

Psychology Stanford Prison Experiment (SPE): Icon and Controversy
David C. Devonis
  • LAST MODIFIED: 26 August 2020
  • DOI: 10.1093/obo/9780199828340-0269


The Stanford Prison Experiment (SPE) took place at a time when the sources of authoritarianism and evil were a focal concern in psychology. It emerged from a tradition of activist social psychological research beginning with Solomon Asch in the 1940s and extending through Stanley Milgram’s obedience experiments in the early 1960s. The SPE was a product of the research program of social psychologist Philip Zimbardo, a member of the Stanford psychology faculty since 1968. Discussions among Zimbardo’s students in spring 1971 led to a plan to simulate a prison environment. They converted portions of the basement of a University building into a combination booking room and jail. Zimbardo and a number of his graduate and undergraduate students took on supervisory roles. Before the Experiment began, paid participants recruited through newspaper advertisements were screened to eliminate obvious psychopathology, then randomly assigned to either the role of ‘guard’ or ‘prisoner.’ On the first experimental morning August 14, 1971, actual local police simulated an arrest of each of the prisoner participants. After they arrived, blindfolded, a simulated booking took place. Guards escorted them to the prison hallway where prisoners were required to strip and exchange their clothing for simple shifts and slippers. After a simulated spray delousing, they entered makeshift cells. After this, the Experiment evolved as an extended improvisation, by both the guards and prisoners, on prison-related themes. Episodes of deprivation, bullying, and humiliation emerged unplanned. Originally planned to run for two weeks, the Experiment lasted only six days, prematurely terminated when its supervising personnel judged that the simulation had gotten out of their control. The coincidence of its termination with the Attica prison uprising in New York led to its immediate dissemination in the news. Since then the SPE has become one of the most iconic psychological studies of psychology’s modern era. Although intended to expose and ameliorate bad prison conditions, its effectiveness in this regard diminished during a rapid shift in US prison policy, in the mid-1970’s, from reform to repression. Over succeeding decades, the Experiment continued to stimulate the popular imagination, leading to an extensive replication on British television and its portrayal in two feature films. Soon after its original publication, the SPE attracted criticisms of its methodology. After 2010, critical scrutiny of the SPE as well as similar iconic studies from the 1960s and 1970s increased, fueled by the growing ‘replication crisis’ in psychology. This most recent phase of criticism reflects not just a turn toward reflexive disciplinary self-criticism but also the increased availability of archival sources for examination. The SPE continues to excite both passionate support and equally passionate obloquy, much as have other comparable simulations of human social behavior.

Archival Sources

Philip Zimbardo, the primary investigator of the SPE, has been unusually generous in making archival donations during his lifetime. Two of these are physical archives in two different locations: the Zimbardo (Philip G.) Papers at the Stanford University Archives and the Philip Zimbardo Papers at the Drs. Nicholas and Dorothy Cummings Center for the History of Psychology (CCHP) at the University of Akron. Alongside these is a virtual archive, the Stanford Prison Experiment website, maintained for over twenty years by Zimbardo and others. The Stanford Prison Experiment: 40 Years Later, a website constructed by the Stanford University archivist in connection with an exhibition at Stanford, contains links to much of the transcribed data collected by Zimbardo and his colleagues in 1971. Le Texier 2018 and Le Texier 2019 (cited under Thibault Le Texier) represent the most complete use of the archives to date, and citations in these critiques of the SPE form a virtual finding aid for the many subdivisions of the available archival material.

  • Philip Zimbardo Papers. Drs. Nicholas and Dorothy Cummings Center for the History of Psychology (CCHP). Univ. of Akron, Akron, Ohio.

    This collection, a subset (4.5 linear feet in 16 boxes) of the Stanford Zimbardo archive, is focused on the SPE. It contains SPE-specific materials, teaching materials, and materials relating to the development of Zimbardo 2008 (cited under Primary Documentation of the SPE). The CCHP also holds several oversize folders of SPE materials and has some of the original props and costumes from the SPE. The finding aid also has a brief Zimbardo biography. The finding aid is available online.

  • The Stanford Prison Experiment.

    Well-designed and informative website, maintained with National Science Foundation (NSF) funding under sponsorship of the Social Psychology Network, with links to much of the primary documentary and contextual material relating to the SPE as well as to major media presentations of the Experiment. Historically it evolved from the original slide show Zimbardo and White 1972 (cited under SPE and Related Experiments in Media) circulated among social psychologists in the 1970s.

  • The Stanford Prison Experiment: 40 Years Later In Stanford Libraries: Special Collections and University Archives.

    This site contains copies of material related to the SPE from the Stanford Archives, including accessible transcripts of several documents related to the SPE such as the original informed consent forms, audio clips, and photos, as well as links to the original eighty-slide slideshow from the 1970s.

  • Zimbardo (Philip G.) Papers. Stanford University Archives, Collection SC0750.

    This collection runs 256 linear feet in 182 boxes, and contains material directly and peripherally related to the SPE, including a substantial amount of audiovisual and film material and materials used in Zimbardo’s classes at Stanford. The finding aid, available online, has a brief Zimbardo biography attached.

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