- Male psychology students at the prestigious Stanford university in California.
- Voluneered to be participants in the study.
- Randomly allocated into two groups - Prisoners and prison guards.
- Prisoners: To spend 2 weeks locked in cells in a wing of the university.
- Prison guards: To look after the prisoners and keep them under control.
- Prisoners arrested at home unexpectantly and taken to the university, stripped, deloused and given prison uniforms and prison numbers.
- Prisoners to spend 23 hours a day locked in their cells.
- Prison guards given uniforms with sticks and sunglasses.
- Prison guards worked shifts and went home after shifts.
- Called off after 6 days.
- Guards became brutal.
- Two prisoners had some form of nervous break down.
- One prisoner developed a nervous rash.
- One prisoner went on a hunger strike.
- Guards gave orders and prisoners became apethetic - Did as they were told, though it caused them distress.
- Conformed to social roles.
- Deindividualisation - Immersed in the norms of the group, lose sense of identity.
Strengths and weeknesses
+ Maintained a degree of control and some ecological validity - As close to real life as possible (EG prisoners arrested from home).
+ Zimbardo collected data efficiently.
- Unrepresentative sample - 24 healthy, male college students. Middle class and white.
- Lacks ecological validity - Couldn't be completely realistic.
- Deception - Being unexpectedly arrested at home.
- Experiment was abandoned after the 6 days.
- Approval for the study was given by the Office of Naval research.
- No suitable alternative methodologies.
- Extensive group and individual debriefing sessions held.
- Benefits gained about understanding human behaviour.