The chapter frames SPE as a natural complement to Milgram’s obedience research: Milgram quantified aggression and obedience with a simple, powerful setup; SPE demonstrates the evil good people can do to others when placed in socially approved roles within a legitimizing ideology and institutional support.
SPE subjects endured six days and nights of intense, escalating hostility between guards and prisoners, unlike Milgram’s shorter sessions where distress tended to fade after the learning that harm was not real. Example from a guard’s diary: “During the inspection… the prisoner… grabbed my throat, and although I was really scared, I lashed out with my stick and hit him in the chin.”
The authority in SPE was typically not visible to participants but operated as an agency through the experimenter (Zimbardo as Prison Superintendent), overseeing ongoing confrontations between opposing forces.
Zimbardo’s reflections situate SPE within a broader trajectory of social-psychological research on deindividuation, dehumanization, and the power of situations to override dispositions.
Personal anecdotes and connections:
Zimbardo and Milgram were high school classmates; both favored situational explanations over dispositional ones for irrational behaviors.
Milgram’s fear of data “being stolen” and the collaboration (and eventual renewal) of their friendship/research program; Milgram’s concern with the ethics and limits of “dark side” research.
Zimbardo’s encounters with Kurt Lewin’s lineage (Lewin as intellectual grandfather of Milgram, Allen Funt, and Zimbardo himself) and the Lewin tradition of translating real-world questions into laboratory tests.
Enthusiasm for Candid Camera as a vehicle for revealing obedience/conformity, and the idea that experimental setups can educate and influence public understanding of social behavior.
Anecdotes about the origin of Funt collaboration and Lewin’s influence culminate in the sense that SPE embodies a public-facing psychology—“to give psychology away to the public.”
The SPE: What It Was, Where It Came From, And What Came Out Of It
The SPE was a laboratory simulation of prison life designed to study how ordinary people transform under institutional power and role assignment.
Setup and realism:
A mass arrest scenario in Palo Alto created a social environment with “mundane realism”: police arrests, processing, and a basement prison.
70 volunteers responded; of these, 24 were selected after psychological testing/interviews by Craig Haney and Curtis Banks. They were randomly assigned to two roles: mock prisoners and mock guards.
The setting included a stark basement prison: barren hallway, barred doors, solitary confinement spaces, a 30-foot yard, and an observation post; cells were bugged; guards wore military-style uniforms and selected by the guards themselves during a preliminary orientation.
The prisoners wore smocks with numbers, no underwear, ankle chains, nylon stocking caps, and rubber sandals; guards wore uniforms with billy clubs, and rules labeled prisoners by number and guards as “Mr. Correctional Officer.”
Data collection was extensive: daily videotapes, diaries, interviews, tests, daily reports, and follow-up surveys; visitors and external observers were present (Visitors’ Night, parole boards, etc.).
Participants signed informed consent; the study was approved by the university Human Subjects Review Board with minor limitations; the study noted that some civil rights would be suspended for prisoners, with only minimally adequate diet/health care.
Duration and outcome:
The study was planned as up to a 2-week duration but was terminated after 6 days due to escalating pathologies and ethical concerns.
By end: “too many normal young men were behaving pathologically as powerless prisoners or as sadistic, all-powerful guards”; some prisoners displayed extreme stress reactions; a number of guards became coercive and dehumanizing; the line between normal and pathological behavior blurred rapidly.
Key data points and dynamics:
Nine prisoners filled three cells; three guards per shift; back-up guards on standby; one prisoner replaced midweek.
The operational rules and environment were designed to be coercive yet not explicitly instructive on cruelty; the study allowed for improvisation by participants within the given framework.
Observational data showed a rapid escalation of coercive tactics, humiliation, and dehumanization by guards; prisoners experienced sleep deprivation, isolation, and various punishments; a “privilege cell” tactic emerged to divide and manipulate the group.
Immediate findings and implications:
The SPE demonstrated the power of a total environment, roles, norms, and institutional validation to transform behavior, sometimes independently of explicit commands from an authority figure.
It highlighted how a relatively ordinary cohort could evolve into a dysfunctional system with a prison ethos, illustrating the potential for institutions to shape moral action.
Genesis of the Experiment: Why Did We Do This Study?
Three drivers for SPE:
1) Conceptual: Build on deindividuation, vandalism, and dehumanization research showing anonymous or deindividuated individuals can engage in anti-social acts when placed in total environments (Lifton, Lifton’s totalism; deindividuation literature).
2) Conceptual: Test the power of social situations beyond overt authority, addressing the limits of dispositional explanations by focusing on roles, norms, group identity, and situational validation.
3) Pedagogical: Rooted in a social psychology course where students reversed roles to explore Psychology of Imprisonment and learned from mock prison experiences; the experience helped frame a controlled experiment to avoid self-selection biases.
Conceptual threads:
Deindividuation and dehumanization can be triggered by anonymous, highly structured environments, leading to extreme behavior.
The study aimed to show how situational factors can override personal dispositions and transform ordinary people into agents of cruelty or indifference.
Inspired by broader concerns about brainwashing/milieu control and the Korean War/Chinese indoctrination literature (Schein’s work on brainwashing).
Pedagogical lineage:
A social psychology course spawned a weekend mock prison experiential learning session led by students (David Jaffe and team); its powerful effects motivated the controlled experiment to rule out self-selection.
Early opportunities and cautions:
The plan was to create a lasting social laboratory to observe how institutional environments alter behavior, while remaining mindful of ethical considerations and the need to translate findings into real-world implications for institutions.
Ten Lessons Learned From the SPE
Some situations exert powerful influences over individuals, causing behavior beyond what people would predict outside the situation. (Reference: Ross & Nisbett, 1991)
Situational power is most salient in novel settings where there are no established guidelines; personality variables have limited predictive utility in such contexts.
Historical accounts rely on self-reported dispositions rather than predictive self-knowledge in new environments.
Situational power involves ambiguity of role boundaries and institutional permission to behave in prescribed or disinhibited ways; ideological justifications provide “cover stories” for actions.
Role-playing, even if artificial, can profoundly shape private attitudes and beliefs through dissonance effects; lower justification strengthens the likelihood of internalizing the role; group pressures align with emergent norms of dehumanizing prisoners.
Good people can be seduced into evil within total situations; Dr. Jekyll–Mr. Hyde-like transformations occur under structured power dynamics; Lifton’s framework is invoked to explain such transformations.
Human nature can transform dramatically in powerful social settings, prompting comparisons to Nazi guards, cults, and modern mass violence; this has sustained interest in the SPE for decades.
Despite laboratory artificiality, such research can generalize to real-world contexts; parallels exist with immigration detention centers and other institutions showing abuse of power under closed systems (e.g., Browning’s Ordinary Men example).
Selection for specialized tasks may benefit from simulated role-playing rather than relying solely on personality tests; experiential screening can uncover situational adaptability and restraint.
Researchers should move beyond mere observation to advocacy for social change; the SPE’s insights have been used to inform policy, training, and public understanding.
Prisons exemplify a social-political experiment that can degrade humanity; contemporary policy debates (e.g., Three Strikes laws) demonstrate the broader societal costs of punitive systems and the need to transform institutions, not just individuals.
Ethics of the SPE
Was the SPE unethical? A nuanced answer:
No: It followed Human Subjects Review Board guidelines; prisoners acknowledged rights suspension and only minimal care; no deception about the nature of the study; observers and staff witnessed deterioration without intervening against the process.
Yes: It was unethical because participants suffered psychological distress and moral injury; the dual roles of investigator/guardian and prison administrator blurred accountability; the decision to end the study was debated, and ending it on Day 6 may have been too late for some subjects.
Key ethical tensions:
The balance between methodological insight and participant welfare.
The conflict of roles (principal investigator vs prison superintendent) and the potential for coercive influence on participants.
The responsibility to intervene when harm emerges, versus preserving experimental integrity.
Positive Consequences
The SPE popularized the power of the situation in textbooks and public discourse, reinforcing that behavior is not solely dispositional.
The SPE influenced legislative changes, including Birch Bayh’s efforts to separate juveniles from adult pre-trial detention due to violence risk, demonstrating policy impact from laboratory findings.
The SPE was presented to civic, judicial, military, and law enforcement groups to raise awareness about prison life; role-playing procedures were used in mental health staff training to simulate patient responses to ward conditions and staff insensitivity; replication occurred in New South Wales (Lovibond, Mithiran, & Adams, 1979).
SPE-inspired research programs emerged, including work on shyness (Shyness Clinic) and time perspective (how past/present/future timeframes shape behavior), revealing links between arousal, social context, and pathological symptoms in normal subjects.
Notably, many SPE conversations focused on the present (60–80% in some analyses), with less attention paid to past/future.
Personal trajectories of SPE participants and affiliates:
Carlo Prescott, prison consultant, re-entered public life after 17 years in prison; later built a radio program and engaged in community teaching.
Doug Korpi (prisoner 8612) pursued a clinical Ph.D., internship in San Quentin, and a career as a forensic psychologist; inspired the Quiet Rage project.
Craig Haney earned a Law degree and Ph.D.; became a leading consultant on prison conditions and legal issues in prisons.
Christina Maslach advanced burnout research, focusing on institutional solutions rather than solely individual therapy; explored positive aspects of individuation and reform in care settings.
The SPE also influenced broader cultural impact, including a rock band named Stanford Prison Experiment inspired by the work.
An Outsider's View of the Stanford Prison Experiment (Christina Maslach)
Maslach joined the project late as an interview collaborator; she visited the prison, observed shifts, and witnessed a transformation in guards (e.g., a sympathetic “John Wayne” guard becoming mean and belligerent on late-night shifts).
Notable observations:
The guard nicknamed “John Wayne” was actually a mild-mannered person when encountered earlier; on night shifts he adopted a southern accent and aggressive prison-film persona, illustrating rapid role assimilation.
The bathroom routines required hooding prisoners and moving them out of sight to preserve the total environment; Maslach recalls the unsettling scene of hooded prisoners led to a sense of moral unease.
An emotional breakdown of a prisoner within ~36 hours prompted Maslach to reconsider the ethical balance; she was appalled by the treatment and argued that the study was harming participants.
The incident sparked a confrontation with Zimbardo, leading to reflections on the ethical responsibilities of researchers. Ultimately, the decision to debrief and halt the study followed, marking a shift in Maslach’s own career toward burnout and ethical institutional reform.
Maslach’s insights:
The experience revealed how frontline researchers can become desensitized to the consequences of the environment they helped create, attributing failures to dispositional factors rather than situational conditions.
It highlighted the danger of psychological “individualism” in legal and clinical thinking, urging contextualized analysis of social and institutional factors.
The SPE inspired Maslach’s burnout research, emphasizing organizational conditions that degrade human care rather than focusing solely on individual pathology.
The SPE and the Analysis of Institutions (Craig Haney)
The SPE, Milgram, and the spirit of the times: The SPE emerged in an era of shifting perspectives on social psychology, with a growing emphasis on structures, contexts, and situations rather than solely on dispositional explanations.
Key tensions and relationships:
Milgram’s obedience paradigm created a backdrop for studying power, but SPE differed in its emphasis on roles, symbolic structures, and the institutional setting rather than a direct, visible authority figure.
Mischel’s critique of traits and the rise of situationism informed the SPE’s approach to how environments shape behavior.
Goffman’s insight on total institutions and Rosenhan’s critique of psychiatric settings informed the notion that institutional contexts can redefine identities and behaviors.
The role of the researchers within the SPE:
Haney and Banks reviewed personality profiles, selected “abnormally normal” subjects, and assigned them to prison roles; they then acted as observers rather than direct guardians of the prisoners’ welfare.
The presence of counselors who interacted with prisoners to monitor well-being created ongoing proximity to the internal dynamics, allowing data collection but also altering relationships between prisoners and staff.
Observations about transformed relations:
The psychologist (Haney/Banks) emerged as an administrator within the prison system, gradually becoming seen as part of the establishment by prisoners and guards alike; this fostered distrust and hedged the ability to intervene.
The role-conflict and ambiguity of “helper” within a coercive environment revealed the costs to researchers who attempt to preserve humane ethics while observing systemic harm.
Outcomes and reflections:
The SPE illuminated how institutional environments, rather than just individual dispositions, can profoundly shape behavior and moral judgment.
The experience informed Haney’s later work on criminal justice policy, psychology’s role in legal change, and the broader social-psychological understanding of imprisonment.
The SPE and the Power of Institutions (Curt Banks and the Institution Context)
The SPE framed the prison as a microcosm of society’s power structures, with the pilot attempt to observe how ordinary people assume roles that legitimize coercive authority.
Critical design choices:
Subjects were healthy and normal, randomly assigned to guards or prisoners, to test whether a “normal” population would still exhibit extreme behaviors in a prison-like setting.
There was minimal direct intervention to shape events; the aim was to observe naturalistic emergence of norms and behaviors within the emergent prison culture.
Observations of role dynamics:
Guards quickly formed a cohesive group, created “rules,” and escalated coercive tactics with some guards becoming “good guards” by default but never challenging the violent orders of their sadistic peers.
Prisoners showed rapid fragmentation, with some becoming passive “zombies,” other rebels, and a few who tried to maintain some sense of autonomy, often at personal risk.
Maslach’s outsider perspective as described here (see above) highlighted how the counselors’ proximity to the prisoners’ welfare could erode their professional stance and complicate ethical commitments.
Institutional Change in the Years Since Milgram and the SPE
Since the SPE and Milgram’s work, significant changes and ongoing crises in the prison system have been documented.
Trends and concerns:
Overcrowding, the reduction or abandonment of rehabilitative programs, and brutal conditions have persisted in many institutions.
Political rhetoric around crime has emphasized punitive “toughness” without adequate attention to social costs, contributing to mass incarceration and recidivism.
The rise of the “supermax” model and long-term solitary confinement has raised concerns about psychological harm to prisoners and staff alike.
Legal and policy engagement:
Haney and collaborators have participated in numerous lawsuits challenging unconstitutional prison conditions (e.g., Coleman v. Wilson, Toussaint v. McCarthy) and in efforts to reform mental health and medical services in prisons.
Litigation has achieved some relief, but progress is uneven; the higher courts’ willingness to impose broad changes is often tempered by political and bureaucratic inertia.
Systemic critique and reform:
The law often discounts the situational and institutional context in favor of dispositional explanations; the SPE and Milgram emphasize the need to change power structures and norms to prevent abuse.
Legislative and policy reforms must be accompanied by institutional changes, including oversight, accountability, shifts in culture, and targeted interventions to reduce harm.
The Role of Law, Policy, and Public Understanding
Milgram and SPE demonstrated the powerful impact of social context on behavior, challenging the assumption that only “bad people” commit gross abuses.
Legal responses often focus on liability and individual responsibility, but the SPE suggests that changing environments and institutional incentives is essential to changing behavior.
The practical implication is that to reduce harm in prisons and similar institutions, reforms must address power dynamics, normative cultures, and structural supports that enable abuse.
The SPE’s broader public impact included public talks, media appearances (e.g., New York Times Magazine, Psychology Today, television appearances), and the dissemination of educational materials (Quiet Rage video; Candid Camera-related resources).
Conclusion
The SPE—and Milgram’s studies—underscore a central claim: good people can be induced to do evil under the right situational pressures, especially within total institutions with clearly defined roles and norms.
The experience also exposed the researchers themselves to moral hazards and the potential for ethical compromises, prompting authors to reflect on the responsibilities of scientists in shaping social policy and practice.
Over the decades, these studies have informed debates about prison reform, the ethics of social experimentation, and the necessity of system-level changes to reduce harm and promote humane treatment within institutions.
The authors emphasize that the lessons remain relevant: changing behavior requires altering the contextual forces that enable or constrain actions, not merely focusing on individuals’ dispositions.
Final Reflections on Ethics, Public Policy, and Future Work
Ethical balance remains a central consideration: how to study powerful social processes without causing harm; how to protect participants while gaining meaningful insights.
The SPE’s legacy endures in ongoing debates about prison reform, burnout among care workers, and the ethical duties of researchers who study human suffering in institutional contexts.
The call to action remains: continue translating laboratory insights into institutional change, advocate for humane conditions, and monitor power dynamics to prevent abuse in settings where authority is centralized.
References (selected)
Browning, C. R. (1992). Ordinary men: Reserve Police Battalion 101 and the final solution in Poland. New York: Harper Perennial.
Lewin, K. (1951). Field theory in social science. New York: Harper.
Lewin, K., Lippit, R., & White, R. K. (1939). Patterns of aggressive behavior in experimentally created "social climates." Journal of Social Psychology, 10, 271-299.
Lifton, R. J. (1969). Thought reform and the psychology of totalism. New York: Norton.
Milgram, S. (1963). Behavioral study of obedience. Journal of Abnormal and Social Psychology, 67, 371-378.
Milgram, S. (1965). Some conditions of obedience and disobedience to authority. Human Relations, 18, 57-76.
Milgram, S. (1974). Obedience to authority: An experimental view. New York: Harper & Row.
Zimbardo, P. G. (1969). The cognitive control of motivation. In Nebraska Symposium on Motivation (pp. 237-307).
Zimbardo, P. G. (1971). The power and pathology of imprisonment. Congressional Record.
Zimbardo, P. G., Haney, C., Banks, W. C., & Jaffe, D. (1973, April 8). The mind is a formidable jailer: A Pirandellian prison. The New York Times Magazine.
Zimbardo, P. G., & Funt, A. (1992). Candid camera classics in social psychology. New York: McGraw-Hill.
Zimbardo, P. G., Haney, C., Banks, W. C., & Jaffe, D. (1973). Interpersonal dynamics in a simulated prison. International Journal of Criminology and Penology, 1, 69-97.
Zimbardo, P. G., & Leippe, M. R. (1991). The psychology of attitude change and social influence. New York: McGraw-Hill.
Maslach, C. (1976). Burned-out. Human Behavior, 9, 16-22.
Maslach, C. (1982). Burnout: The cost of caring. Englewood Cliffs, NJ: Prentice-Hall.
Maslach, C., Jackson, S. E., & Leiter, M. P. (1996). The Maslach Burnout Inventory. Third edition. Palo Alto, CA: Consulting Psychologists Press.
Maslach, C., & Leiter, M. P. (1997, in press). Preventing burnout. San Francisco, CA: Jossey-Bass.
Haney, C. (1982-1997). Various works on psychology and law, prison conditions, and related topics.
Zimbardo, P. G., & Haney, C. (1978). Prison behavior. In B. B. Wolman (Ed.), International encyclopedia of psychiatry, psychology, and neurology. Vol. 4. New York: Human Sciences Press.
Additional co-authored pieces listed in the references block (as provided in the transcript).