Zimbardo – Revise

Zimbardo's Study of Conformity to Social Roles

The Stanford Prison Experiment

On 14th August 1971 Philip Zimbardo wanted two investigate to what extent done conform to the expectations people have of us. How and why do we conform to social roles? He dissed an experiment where he would build a mock prison and invite “normal”, law abiding citizens to take part. Participants would be randomly assigned, by a flip of a coin, to be a guard or a prisoner. He also offered to pay them $15 a day to take part in the study. 

75 make students volunteered to take place and after a series of psychological tests and background checks Zimbardo picked 24 participants. 9 would be guards and 9 would be prisoners with the reminder on-call if needed.  The guards would work in 3s for 8 hours shifts and the prisoners would be in the prison throughout the experiment, 3 in each cell. Guards were given no training and were free, within limits, to keep law and order in their prison. In fact they were also told about the potential dangers that they could expect in this setting, as would a normal prison guar

Day 1 - The Arrest

The Palo Alto Police arrested the 9 prisoners, unannounced,  at their homes for burglary and armed robbery. They were put in cuffs, searched and taken to the police station with the sirens on. They were booked in, had finger prints taken and read their rights and then left in a holding cell blindfolded.

Still blindfolded they left the station and headed to Stanford University where in a the basement a mock prison had been constructed to be processed and booked in. One by one they were searched, stripped naked and deloused. All of this with an aim to humiliate and dehumanise them. They were issued there uniform which consisted of a dress, with no under clothes. On the uniform had their number and were to be referred to by this number. On their right ankle that had a chain and rather than shaving heads a cap made out of stockings was also given to them. They were also issued with loosely fitting sandals. All of this aimed to dehumanise, demascluinize and embarrass them in a short period of time as this process would often happen over a longer period of time in a real prison. The chain would act as a reminder of where they were even when sleeping and turning over. They immediately started to walk, talk and hold themselves differently. 

The guards also had a uniform. They wore a uniform of khaki, carried a big billy club, a whistle around there neck and sun-glasses. They were reflective sun-glasses so the prisoners could not see the expression in the guards eyes. This uniform adds a sense of identity among the guards, authority and anonymity,

Each cell would sleep 3 prisoners, the corridor was their yard and there was a closet that was named “The Hole” for solitary confinement.

Day 2 - The Rebellion

Prisoners were woken up at. 2:30 am for a roll call that was used frequently to get prisoners to identify with there numbers and push-ups were used as a form off punishment for any infraction. Although all seemed calm as both prisoners and guards adapted to their new social role the prisoners later started to rebel. They took their caps off, their numbers and refused to eat in the yard and barricade themselves in their cells.

The guards responded harshly with more guards staying on and being brought in to deal with the rebellion. They sprayed the prisoners with fire extinguishers to move them away from the doors, stripped at the prisoners naked, removed their cots and forced the ring leaders into “The Hole” They felt as the needed to maintain order and maybe had they been stricter before a rebellion would have not started. They felt that maybe using psychological tactics could help as thyme couldn’t maintain this level of guards on duty at one time. 

One of the tactics they used was to create a privileged cells. Prisoners would be given their clothes back, beds and be fed. This was aimed to create some animosity between the prisoners, ruin the trust, make them believe there was an informant. After around 12 hours they then swapped those in the privileged cell to different prisoners. Again, with the aim of dividing the identity of the prisoners. Bad prisoners were denied toilet rights or had to use a bucket in their cells. 

Only 36 hours into the experiment prisoner 8612 shows signs of distress and after a discussion with Zimabrdo was allowed to be released form the prison. Zimbardo acted more as a superintendent of a prison than an experimenter with care for his participants.

Day 3 - Visiting Hours and The Break In

Day 3 proved to be a busy day. Today was visiting hours. This entire event was manipulated in a way to be as favourable to the the prison as possible. Prisoners were washed, groomed, told to clean their cells and they were fed. Strict rules and discussions see had with visitors in the presence of guards and although some verbal objected they all complied. One parent questing how tired her son looked but didn’t want to cause an issue around it.

There were also rumours that prisoner 8612 was faking his break down and had planned to return with is friends to expose the study and break out the remaining prisoners. Zimbardo with his colleagues devised two plans. The first was to ask the local police station to hold their prisoners but this was not possible due to insurances. 

Zimbardo instead blindfolded his prisoners and took them to an alternative location in the university building and his team dismantled the prison and Zimabrdo waited in the room to confront prisoner 8612 and tell him the experiment had ended. The escape turned out to be a rumour and there was no break in attempt made. A colleague of Zimbardo did enter the room and asked Zimbardo “what is you independent variable” which angered Zimbrado, showing how committed he was to his experiment as he was concerned about a break in and his prisoners not the variables of an experiment.

Day 4 - Prisoner 819 Did a Bad Thing

The guards did not take likely to the effort and wasted time of the rumoured escape. They ramped up their punishments, more and longer roll calls, more push ups and cleaning toilets with their bare hands. 

On the same day a priest was invited to come in to evaluate the realism of the prison. The priest spoke to all but one prisoner. When he introduced himself to them the prisoners responded with their numbers and not their names. He asked them “Son, what are you doing to get out of here?” And discussions of legal aid were had. 

Prisoner 819 did not want to speak to the the priest, he had caused trouble with the guards and had stoped eating and wanted to speak to a doctor. He agreed to speak to Zimbardo and the priest when he broke down. Zimbardo told him to go to the relaxation room and he would be fed and could see a doctor. Shortly after the prisoners could be heard repeatedly chanting in unison “Prisoner 819 did a bad thing”. Zimbardo returned to the relaxation room to find 819 crying and wanting to go back in to prove himself. ZImbardo had to remind 819 and himself that this was only an experiment and he was free to go and would be released.

Day 5 - The Parole Board

On this day any prisoner who felt he had a legitimate reason for parole could file man appeal. They were chained together and blindfolded and ushered to the parole board. Each prisoner was asked if they would relinquish any payment form their time in the experiment to leave and all bar 2 agreed. They were told their request would be considered and they returned to the cells in a docile manner. They had voluntary signed up for this experiment but it now had a new sense of realism, this includes the fact that they had agreed to not be paid so what was in it for them to stay. 

Priosners coped with their frustration of prison life in different ways. By the end of the experiment 4 had been realised for breaking down, others had followed every order of the guards. The prisoners were no longer identified as a group and were deindividualized. The guards themselves had got into routine and with different attitudes with some being fair, some being the “good guys” and others hostile towards the prisoners. It was now clear the guards had control of the prison. 

That evening visors arrived again and some parents asked for Zimbardo to contact a lawyer in order to get their son out of prison. A lawyer was called and spoke to the prisoners. Again, the realism of the experiment took anther turn and Zimbardo realised that he needed to stop the experiment. They had created a prison, they had created a place of suffering. The good guards did not interfere with the cruel guards as power acted as an aphrodisiac for some of the guards. 

Day 6 - Liberation

They had a series of encounter groups with the guards and then prisoners, including those who had been released. Finally, prisoners, guards and staff all met together. Reflections were made about how they acted and how they would want to act in the future. 

On the next day 20th the mock prison was closed down and taken apart. 


The guards and prisoners conformed to their roles very quickly. Zimbardo and his team also confirmed to their roles rather than being objective experimenters. Zimbardo claimed that this proved how our social roles can influence our behaviour as well mannered members of society with a title acted in a way not consistent with their normal behaviours and attitudes.


Zimbardo’s experiment is a controlled observation so we can say that it has good internal validity. He was able to have some control over the prison and its inmates and guards. We can also have confidence as the participants were randomly allocated to prisoners and guards. 

There are issues regarding the experiments ecological validity and therefore its external validity. Although they tried to make the prison realistic there are plenty of limitations. The prison is small, the prisoners all arrived at the sae time whereas in a real prison the inmates would come and go on a regular basis. The uniforms that they wore were not also realistic but to speed up the process of dehumanising etc…

Banuazizi and Mohavedi (1975) criticise the experiment and say that the participants were just well played actors. They knew what was involved in the experiment and therefore may play towards the role of a guard or prisoner, demand characteristics. One participant stated that they based their behaviours on the charter John Wayne. Zimbardo argues that this is not the case and that from observations 90% of prison conversation was about prison life. However, as it was Zimbardo and his team making the observations we have to be mindful of observer bias. This is more important when we consider how far Zimbardo associated himself to the experiment.

Dispositional Factors

Fromm (1973) argues that Zimbardo has exaggerated his results and ignores dispositional facts, types of personalities. A third of the guards were fair, a third of the guards were kind and gave the prisoners cigarettes and the final third were more hostile. So does this mean is it the role that determines the behaviour or are their specific personality traits that determine how we are in different social roles.

Social Identify Theory

Tajfel’s social identity theory can be used as a potential explanation of why the participants confirmed to their social role and why the prisoners eventually became subdued and the guards became more cohesive. Initially there was a sense of identity for both the guards and the prisoners, therefore they stick together as a unit. Once the prisoners rebelled this united the guards and the drove the prisoners apart through various techniques such as the privileged cell. This tore the identity of the prisoners and therefore their support of each other. We can see the opposite happen in the BBC’s replication of the Stanford prison experiment study.

Supporting Evidence

A similar experiment was conducted by Orlando in 1973. Over 3 days, 29 staff of a psychiatric ward were admitted as patients. This was compared to another 22 members of staff as a control. A similar experiment was conducted by Orlando in 1973. Over 3 days, 29 staff of a psychiatric ward were admitted as patients. This was compared to another 22 members of staff as a control. Over the course of the study the patients expressed of anxiety and depression, feeling trapped and isolated. They said they felt a loaf of identity. 

This support for Zimbardo’s experiment allows us to reflect on both prison and hospital life. How we interact with inmates and patients, how they may feel and how to get the best outcome for both. 

Contradicting Evidence

The BBC replicated the Stanford experiment but with 10 prisoners and 5 guards. The prisoners were told that on day 3 one of them would be promoted to a guard. The prisoners behaviour would play up to the guards so to improve their chances of being promoted to a guard. However, after day 3 there was no longer a need to do this. This strengthened the identity of the prisoners and on day 6 there was a rebellion where the prisoner gained control and wanted to lead the prison regime working alongside the guards. 

This contradicts Zimbardo’s original study as this time the guards were not able to form an identity and the prisoners were able to keep together. It also showed that the roles could be flexible with the promotion to a guard rather than a fixed position. The study needed after 6 days following guidance from an ethic committee as participants were showing signs of stress. All participants were fully debriefed and had access to counselling. This replication is criticised as some argue that the behaviours of the participants was staged for TV and we also have to consider the demand characteristics. 


There were some serious issues regarding the ethics of this study. Participants were humiliated and punished, stripped naked, woken up at random times etc… They were not protected from psychological harm. Participants should also have the right to withdraw and when they discussed this with Zimbardo he would initially question their motives and try to assess their need to leave or encourage them to stay.

A big issue with the study is ZImabrdo’s role within it. As an experimenter he has a duty of care to both the research and his participants. Zimbardo got carried away with this experiment and acted more as a superintendent. He was more concerned about the day to day running of his prison than gather results from his observations. This was clearly seen in his response to the rumours of a break in. The replication from the BBC shows greater considerations in its ethics with the experiment being stopped early on their recommendation, a full debrief and counselling to care for the participants in the aftermath if the experiment.