24 US male student volunteers
- randomly assigned role of prisoner or guard
prisoners unexpedctly arrested at their homes
they were deloused, given prison uniform and ID number
- given some rights e.g. 3 meals, supervised toilet trips and 2 visits per week
guards were given uniforms, clubs, whistles and reflective sunglasses aswell as power over the prisoners
- uniforms created a loss of personal identity - more likely to conform to given social role
zimbardo took the role of prison superintendent
- planned duration was 2 weeks but stopped after 6 days