Background to the study

Haney et al set up a mock prison in order to investigate the conditions under which people become aggressive.  They observed that prisons in the US were riddled with conflict and wanted to understand how the conflict between guards and prisoners arose.  The Navy funded the research because they also wanted to understand the high levels of aggression in naval prisons.

At the time, the main explanation for conflict in prisons was centered on blaming the prisoners for being evil people.  Prisoners were seen as aggressive types that were naturally disposed to violence.  Others disagreed with this explanation and suggested that the close contact between prisoners and guards created a situation where conflict could arise.

Aim

To investigate prisoner-guard conflict in a simulated prison environment.

Procedure

An advert was placed in a newspaper asking for volunteers to take part in a study of prison life. 

From 75 respondents, 22 participants were selected to take part in the experiment.  One dropped out, leaving 10 prisoners and 11 guards who were randomly assigned to the two roles.

All participants were male college students assessed as psychologically healthy.  Each was paid $15 per day (a lot in 1973) for their participation.

A simulated prison was set up in the basement of Stanford University, consisting of 3 cells with steel bar doors, a yard area, a guardroom and a closet for solitary confinement.  There was also a room with video recording equipment to record transactions between the participants throughout the proposed 2-week experiment.

The guards were briefed before the experiment and asked to maintain order in the prison.  However, they were not given exact instructions on how to behave.  They were dressed in military-style uniforms and given batons. 

The prisoners were arrested by real officers from the Palo Alto City Police Department at their homes and charged on suspicion of burglary or armed robbery.

They were handcuffed, searched and taken to the police station to be processed.  The prisoners were then blindfolded and driven to Stanford University where they were stripped and deloused.  Each prisoner was given a muslin smock to wear, labelled with their prisoner identification number;  they were referred to by this number for the duration of the study.

The prisoners spent a lot of time in their cells, but were allowed privileges, such as watching a movie and visits from their family.  Three guards worked 8-hour shifts and conducted a ‘prisoner count’ at the start of every shift, lining up the prisoners who then recited their identification number.

Results

After only a few hours, the guards were observed to become increasingly aggressive and controlling towards the prisoners.  This increased throughout the study, and prisoners were punished with push-ups and solitary confinement and verbally assaulted. 

On the second day, the prisoners rebelled by barricading themselves in their cells.  This was soon quashed by the guards who used a fire extinguisher to break into the cells and then placed the ringleaders into solitary confinement.

Over the course of the next few days, the guards increasingly intimidated the prisoners and there was an escalation in verbal aggression and punishment.  Individual differences were apparent, as some prisoners were passive while others were actively rebellious.  There were also differences in the guards: some instigated aggression while others were more reluctant to engage in conflict.

The study was prematurely stopped after just 6 days because the behaviour of the prisoners and the guards was getting out of control.  Many of the prisoners were displaying signs of anxiety and depression and were desperate to leave the study.

Conclusions

It was clear that both the prisoners and guards conformed to the role that they had been assigned. 

The prisoners because submissive and passive, the guards aggressive and hostile. 

The uniforms deindividuated them, facilitating this change in behaviour; they lost their personal identity and adopted the identities they were given. 

The prisoners in particular were stripped of their personal identity.  They were never referred to by name, only by identification number.  They were humiliated and broken down through menial tasks and punishments. 

Both prisoners and guards were immersed in the simulated prison environment.

Evaluation

• Strength: there is evidence to indicate that the prisoners and guards were not acting. The recordings made of their transactions showed that most of the time the prisoners talked about prison life rather than their personal lives.  This shows that they were becoming immersed in the situation rather than merely acting, so this is a strength of the study.

• Strength: the study has informed the way in which prisons are run and can explain the atrocities that have occurred in prison situations.

• Strength: Each participant was fully debriefed and given psychological evaluations after the study to ensure their well-being.

• Weakness: Distress was caused to the ‘prisoners’. They were subjected to physical and psychological harm at the hands of the ‘guards’.  One participant was removed from the prison after just 35 hours because they were so emotionally distressed.  The study was stopped after 6 days because the behaviour of the participants was clearly getting out of hand. 

• Weakness: There was a clear difference between a real prison and Haney’s simulation as the guards and prisoners all knew it was a simulation and that they would only be imprisoned for a maximum of 2 weeks.  Both the prisoners and guards could have simply been acting in a way they thought was expected of them rather than demonstrating real behaviour in the situation.  This lowers the ecological validity of the study (true in real life).

Summary

The Stanford Prison Experiment is a classic study in psychology because it revealed the conditions under which conflict can arise through deindividuation and conformity to social roles.  This has been invaluable for understanding real-life atrocities under similar conditions.  However, it has been accused of being unrealistic, as the participants could simply have been acting the part.  The researchers have also been heavily criticised for not recognising early enough the harm that was being caused to the young men involved.