Haney,Banks,& Zimbardo, (1973)


Relevant Background Information:
The study was funded by the US Navy.
Dispositional hypothesis; the conditions of prisons are due to the nature of the prison guards and prisoners.

The dispositional hypothesis states it is not the prison environment that makes people act in the ways that they do but rather the dispositions (character traits) of those who live and work there.
Zimbardo argues that it is the situation that makes people act the way they do rather than their disposition.
If Zimbardo’s hypothesis is true than there is a possibility for prison reform.

To show how the taking of social roles would lead to excessive conformity to those roles.
To test the dispositional hypothesis.

This study is usually referred to as an experiment, however it is also called a simulation.

Data was collected through video, audiotape, direct observation, interviews and questionnaires.

Quantitative and qualitative.

Independent Variable: the conditions the participants were randomly assigned: prisoner or guard.
Dependent Variable: The resulting behavior.
Prisoners were ‘arrested’ the night before the experiment and brought to the psychology building’s basement where the prison simulation was set up.
Upon the prisoner’s arrival they were stripped and deloused. Then, they were fingerprinted and blindfolded.
Guards were briefed upon rules; they could not physical punishment or aggression, they were encouraged to break down prisoners psychologically (i.e. losing sense of identity)Guards task was to “maintain the reasonable degree of order within the prison necessary for effective functioning.”

The simulated prison;
3 6”9 cells: 3 prisoners
to a cell, a cot (with mattress, sheet, and pillow) for each prisoner
Solitary confinement: ‘The Hole’ a very small, unlit room (2 x 2 x 7 ft) across from cells.
Guard’s quarters: Rooms in an adjacent wing used to change in and out of uniform and for relaxation, interview rooms and a bedroom for the ‘warden and superintendent’ (Zimbardo)
The Yard: A small, enclosed room
To recreate a real prison the researchers consulted a former prisoner.
An intercom system was installed.
No clocks or windows.
-Made to fit the roles of the participants.
-Prisoners had loose fitting smocks, containing ID numbers.
-Prisoners were to wear chains around their ankles, along with caps on their hair.
The effect the uniforms had on the participants was they were able to identify with their roles in a more realistic way. If the participants were dressed as prisoners, they would in turn begin to feel like prisoners, resulting in prisoner behavior.


The experiment came to end very quickly,lasting only 6 days rather than the expected 14. The prisoners began to suffer a wide array of humiliations and punishments at the hands of the guards, and many began to show signs of mental and emotional distress.Within a very short time both guards and prisoners were settling into their new roles, the guards adopting theirs quickly and easily. As the guards adjusted to their power, they quickly began to abuse it. Prisoners were deprived of their basic rights, and soon lost their personal identity.Prisoners were taunted with insults and were generally dehumanized.Researchers themselves began to lose sight of the reality of this situation.The study rejects the dispositional hypothesis.People will readily conform to the social roles they are expected to play, these roles shape the attitudes and behavior of people.

-High levels of control
-Realistic setting made it easier for participants to portray their role.
Uniforms enabled participants to identify themselves as their role.
-Roles were randomly assigned.
-Data was collected through many forms of qualitative approaches.

-Participants were volunteers chosen through an advertisement in a newspaper, paid $15 daily. The participants were possibly acting differently to receive their pay. Participants experienced emotional distress and psychological torment.

Prisoners were deprived of their rights; searched, stripped naked, and deloused.
Toilet facilities became a privilege, access to the bathroom was frequently denied.Prisoners were often stripped and subjected to humiliation, as a weapon of intimidation.

Zimbardo however, believes otherwise:
-Study was funded by the US Navy and supported by the Office of Naval Research
-Deception only occurred during the arrests of the participants.
-Consent forms were signed stating their basic living needs.
-Debriefings of participants took place.
-Advice of other psychologists was taken into consideration
- The study was stopped early.


The validity of this experiment is often criticized:
-This study was a field experiment rather than a scientific experiment which meant there was only observational results but no scientific evaluation.
-Experiment conditions are difficult to replicate
- Subjects were selected and paid- this may have created a pre-disposition towards their violent force. Only male subjects were studied.

However, the study was able to maintain some degree of control.
-Participants were chosen in “healthy conditions”. Guards and prisoners were randomly assigned to their roles.
-Realistic setting of prison made it seem as a true scenario.
- Experiment took place in Stanford University; due to it’s prestige, the validity of the results and experiment itself are less likely to be questioned.