A Simulation Study of the
Psychology of Imprisonment
Conducted at Stanford University
What happens when you put good people in an evil place? Does humanity win over evil, or does evil triumph? These are some of the questions we posed in this dramatic simulation of prison life conducted in the summer of 1971 at Stanford University.
How we went about testing these questions and what we
found may astound you. Our planned two-week investigation into the psychology
of prison life had to be ended prematurely after only six days because of what
the situation was doing to the college students who participated. In only a few
days, our guards became sadistic and our prisoners became depressed and showed
signs of extreme stress.
A Quiet Sunday
On a quiet Sunday morning in August, a Palo Alto,
California, police car swept through the town picking up college students as
part of a mass arrest for violation of Penal Codes 211, Armed Robbery, and
Burglary, a 459 PC. The suspect was picked up at his home, charged, warned of
his legal rights, spread-eagled against the police car, searched, and
handcuffed -- often as surprised and curious neighbours looked on. The suspect
was then put in the rear of the police car and carried off to the police
station, the sirens wailing.
The car arrived at the station, the suspect was brought inside, formally booked, again warned of his Miranda rights, finger printed, and a complete identification was made. The suspect was then taken to a holding cell where he was left blindfolded to ponder his fate and wonder what he had done to get himself into this mess.
Consider the police procedures that make arrestees feel confused, fearful, and dehumanized.
suspects had done was to answer a local newspaper ad calling for volunteers in
a study of the psychological effects of prison life. We wanted to see what the
psychological effects were of becoming a prisoner or prison guard. To do this,
we decided to set up a simulated a prison and then carefully note the effects
of this institution on the behaviour of all those within its walls.
than 70 applicants answered our ad and were given diagnostic interviews and
personality tests to eliminate candidates with psychological problems, medical
disabilities, or a history of crime or drug abuse. Ultimately, we were left
with a sample of 24 college students from the U.S. and Canada who happened to
be in the Stanford area and wanted to earn $15/day by participating in a study.
On all dimensions that we were able to test or observe, they reacted normally.
study of prison life began, then, with an average group of healthy,
intelligent, middle-class males. These boys were arbitrarily divided into two
groups by a flip of the coin. Half were randomly assigned to be guards, the
other to be prisoners. It is important to remember that at the beginning of our
experiment there were no differences between boys assigned to be a prisoner and
boys assigned to be a guard.
Constructing the Experiment
To help us closely simulate a prison environment, we
called upon the services of experienced consultants. Foremost among them was a
former prisoner who had served nearly seventeen years behind bars. This
consultant made us aware of what it was like to be a prisoner. He also
introduced us to a number of other ex-convicts and correctional personnel
during an earlier Stanford summer school class we co-taught on "The
Psychology of Imprisonment."
Our prison was constructed by boarding up each end of a
corridor in the basement of Stanford's Psychology Department building. That
corridor was "The Yard" and was the only outside place where
prisoners were allowed to walk, eat, or exercise, except to go to the toilet
down the hallway (which prisoners did blindfolded so as not to know the way out
of the prison).
To create prison cells, we took the doors off some
laboratory rooms and replaced them with specially made doors with steel bars
and cell numbers.
At one end of the hall was a small opening through which
we could videotape and record the events that occurred. On the side of the
corridor opposite the cells was a small closet which became "The
Hole," or solitary confinement. It was dark and very confining, about two
feet wide and two feet deep, but tall enough that a "bad prisoner"
could stand up.
An intercom system allowed us to secretly bug the cells to
monitor what the prisoners discussed, and also to make public announcements to
the prisoners. There were no windows or clocks to judge the passage of time,
which later resulted in some time-distorting experiences.
With these features in place, our jail was ready to
receive its first prisoners, who were waiting in the detention cells of the
Palo Alto Police Department.
What are the effects of living in an environment with no clocks, no view of the outside world, and minimal sensory stimulation?
A State of Mild Shock...
Blindfolded and in a state of mild shock over their surprise arrest by the city police, our prisoners were put into a car and driven to the "Stanford County Jail" for further processing. The prisoners were then brought into our jail one at a time and greeted by the warden, who conveyed the seriousness of their offences and their new status as prisoners.
Each prisoner was systematically searched and stripped naked. He was then deloused with a spray, to convey our belief that he may have germs or lice -- as can be seen in this series of photos.
A degradation procedure was designed in part to humiliate
prisoners and in part to be sure they wasn't bringing in any germs to
contaminate our jail.
Consider the psychological consequences of stripping, delousing, and shaving the heads of prisoners or members of the military. What transformations take place when people go through an experience like this?
The prisoner was then issued a uniform. The main part of this uniform was a dress, or smock, which each prisoner wore at all times with no underclothes. On the smock, in front and in back, was his prison ID number.
On each prisoner's right ankle was a heavy chain, bolted
on and worn at all times. Rubber sandals were the footwear, and each prisoner
covered his hair with a stocking cap made from a woman's nylon stocking.
It should be clear that we were trying to create a functional simulation of a prison -- not
a literal prison. Real male prisoners don't wear dresses, but real male
prisoners do feel humiliated and do feel emasculated. Our goal was to produce
similar effects quickly by putting men in a dress without any underclothes.
Indeed, as soon as some of our prisoners were put in these uniforms they began
to walk and to sit differently, and to hold themselves differently -- more like
a woman than like a man.
The chain on their foot, which also is uncommon in most
prisons, was used in order to remind prisoners of the oppressiveness of their
environment. Even when prisoners were asleep, they could not escape the
atmosphere of oppression. When a prisoner turned over, the chain would hit his
other foot, waking him up and reminding him that he was still in prison, unable
to escape even in his dreams.
The use of ID numbers was a way to make prisoner feel
anonymous. Each prisoner had to be called only by his ID number and could only
refer to himself and the other prisoners by number.
The stocking cap on his head was a substitute for having
the prisoner's hair shaved off. The process of having one's head shaved, which
takes place in most prisons as well as in the military, is designed in part to
minimise each person's individuality, since some people express their
individuality through hair style or length. It is also a way of getting people
to begin complying with the arbitrary, coercive rules of the institution.
The guards were given no specific training on how to be
guards. Instead they were free, within limits, to do whatever they thought was
necessary to maintain law and order in the prison and to command the respect of
the prisoners. The guards made up their own set of rules, which they then
carried into effect under the supervision of Warden David Jaffe, an
undergraduate from Stanford University. They were warned, however, of the
potential seriousness of their mission and of the possible dangers in the
situation they were about to enter, as, of course, are real guards who
voluntarily take such a dangerous job.
As with real prisoners, our prisoners expected some
harassment, to have their privacy and some of their other civil rights violated
while they were in prison, and to get a minimally adequate diet -- all part of
their informed consent agreement when they volunteered.
This is what one of our guards looked like. All guards
were dressed in identical uniforms of khaki, and they carried a whistle around
their neck and a billy club borrowed from the police. Guards also wore special
sun-glasses, an idea I borrowed from the movie "Cool Hand Luke."
Mirror sunglasses prevented anyone from seeing their eyes or reading their
emotions, and thus helped to further promote their anonymity. We were, of
course, studying not only the prisoners but also the guards, who found
themselves in a new power-laden role.
We began with nine guards and nine prisoners in our jail.
Three guards worked each of three eight-hour shifts, while three prisoners
occupied each of the three barren cells around the clock. The remaining guards
and prisoners from our sample of 24 were on call in case they were needed. The
cells were so small that there was room for only three cots on which the
prisoners slept or sat, with room for little else.
At 2:30 A.M. the prisoners were rudely awakened from sleep by blasting whistles for the first of many "counts." The counts served the purpose of familiarising the prisoners with their numbers (counts took place several times each shift and often at night). But more importantly, these events provided a regular occasion for the guards to exercise control over the prisoners. At first, the prisoners were not completely into their roles and did not take the counts too seriously. They were still trying to assert their independence. The guards, too, were feeling out their new roles and were not yet sure how to assert authority over their prisoners. This was the beginning of a series of direct confrontations between the guards and prisoners.
Push-ups were a common form of physical punishment imposed
by the guards to punish infractions of the rules or displays of improper
attitudes toward the guards or institution. When we saw the guards demand
push-ups from the prisoners, we initially thought this was an inappropriate
kind of punishment for a prison -- a rather juvenile and minimal form of
It's noteworthy that one of our guards also stepped on the
prisoners' backs while they did push-ups, or made other prisoners sit or step
on the backs of fellow prisoners doing their push-ups.
At first push-ups were not a very aversive form of punishment, but they became more so as the study wore on. Why the change?
Because the first day passed without incident, we were surprised and totally unprepared for the rebellion, which broke out on the morning of the second day. The prisoners removed their stocking caps, ripped off their numbers, and barricaded themselves inside the cells by putting their beds against the door. And now the problem was, what were we going to do about this rebellion? The guards were very much angered and frustrated because the prisoners also began to taunt and curse them. When the morning shift of guards came on, they became upset at the night shift who, they felt, must have been too lenient. The guards had to handle the rebellion themselves, and what they did was fascinating for the staff to behold.
At first they insisted that reinforcements be called in.
The three guards who were waiting on stand-by call at home came in and the
night shift of guards voluntarily remained on duty to bolster the morning
shift. The guards met and decided to treat force with force.
They got a fire extinguisher, which shot a stream of
skin-chilling carbon dioxide, and they forced the prisoners away from the
doors. (The fire extinguishers were present in compliance with the requirement
by the Stanford Human Subjects Research Panel, which was concerned about
potential fire threats.)
The guards broke into each cell, stripped the prisoners naked, took the beds out, forced the ringleaders of the prisoner rebellion into solitary confinement, and generally began to harass and intimidate the prisoners.
The rebellion had been temporarily crushed, but now a new problem faced the guards. Sure, nine guards with clubs could put down a rebellion by nine prisoners, but you couldn't have nine guards on duty at all times. It's obvious that our prison budget could not support such a ratio of staff to inmates. So what were they going to do? One of the guards came up a solution. "Let's use psychological tactics instead of physical ones." Psychological tactics amounted to setting up a privilege cell.
One of the three cells was designated as a "privilege cell." The three prisoners least involved in the rebellion were given special privileges. They got their uniforms back, got their beds back, and were allowed to wash and brush their teeth. The others were not. Privileged prisoners also got to eat special food in the presence of the other prisoners who had temporarily lost the privilege of eating. The effect was to break the solidarity among prisoners.
How do you think you would have behaved if you were a prisoner in this situation? Would you have rejected these privileges in order to maintain prisoner solidarity?
After half a day of this treatment, the guards then took
some of these "good" prisoners and put them into the "bad"
cells, and took some of the "bad" prisoners and put them into the
"good" cell, thoroughly confusing all the prisoners. Some of the
prisoners who were the ringleaders now thought that the prisoners from the
privileged cell must be informers, and suddenly, the prisoners became
distrustful of each other. Our ex-convict consultants later informed us that a
similar tactic is used by real guards in real prisons to break prisoner
alliances. For example, racism is used to pit Blacks, Chicanos, and Anglos
against each other. In fact, in a real prison the greatest threat to any
prisoner's life comes from fellow prisoners. By dividing and conquering in this
way, guards promote aggression among inmates, thereby deflecting it from themselves.
The prisoners' rebellion also played an important role in
producing greater solidarity among the guards. Now, suddenly, it was no longer
just an experiment, no longer a simple simulation. Instead, the guards saw the
prisoners as troublemakers who were out to get them, who might really cause
them some harm. In response to this threat, the guards began stepping up their
control, surveillance, and aggression.
Every aspect of the prisoners' behaviour fell under the
total and arbitrary control of the guards. Even going to the toilet became a
privilege, which a guard could grant or deny at his whim. Indeed, after the
nightly 10:00 P.M. lights out "lock-up," prisoners were often forced
to urinate or defecate in a bucket that was left in their cell. On occasion the
guards would not allow prisoners to empty these buckets, and soon the prison
began to smell of urine and faeces -- further adding to the degrading quality
of the environment.
The guards were especially tough on the ringleader of the
rebellion, Prisoner #5401. He was a heavy smoker, and they controlled him by
regulating his opportunity to smoke. We later learned, while censoring the
prisoners' mail, that he was a self-styled radical activist. He had volunteered
in order to "expose" our study, which he mistakenly thought was an
establishment tool to find ways to control student radicals. In fact, he had
planned to sell the story to an underground newspaper when the experiment was
over! However, even he fell so completely into the role of prisoner that he was
proud to be elected leader of the Stanford County Jail Grievance Committee, as
revealed in a letter to his girlfriend.
The First Prisoner Released
Less than 36 hours into the experiment, Prisoner #8612
began suffering from acute emotional disturbance, disorganised thinking,
uncontrollable crying, and rage. In spite of all of this, we had already come
to think so much like prison authorities that we thought he was trying to
"con" us -- to fool us into releasing him.
When our primary prison consultant interviewed Prisoner
#8612, the consultant chided him for being so weak, and told him what kind of
abuse he could expect from the guards and the prisoners if he were in San
Quentin Prison. #8612 was then given the offer of becoming an informant in exchange
for no further guard harassment. He was told to think it over.
During the next count, Prisoner #8612 told other
prisoners, "You can't leave. You can't quit." That sent a chilling
message and heightened their sense of really being imprisoned. #8612 then began
to act "crazy," to scream, to curse, to go into a rage that seemed
out of control. It took quite a while before we became convinced that he was
really suffering and that we had to release him.
Parents and Friends
The next day, we held a visiting hour for parents and
friends. We were worried that when the parents saw the state of our jail, they
might insist on taking their sons home. To counter this, we manipulated both
the situation and the visitors by making the prison environment seem pleasant
and benign. We washed, shaved, and groomed the prisoners, had them clean and
polish their cells, fed them a big dinner, played music on the intercom, and
even had an attractive former Stanford cheerleader, Susie Phillips, greet the
visitors at our registration desk.
When the dozen or so visitors came, full of good humour at
what seemed to be a novel, fun experience, we systematically brought their
behaviour under situational control. They had to register, were made to wait
half an hour, were told that only two visitors could see any one prisoner, were
limited to only ten minutes of visiting time, and had to be under the
surveillance of a guard during the visit. Before any parents could enter the
visiting area, they also had to discuss their son's case with the Warden. Of
course, parents complained about these arbitrary rules, but remarkably, they
complied with them. And so they, too, became bit players in our prison drama,
being good middle-class adults.
Some of the parents got upset when they saw how fatigued
and distressed their son was. But their reaction was to work within the system
to appeal privately to the Superintendent to make conditions better for their
boy. When one mother told me she had never seen her son looking so bad, I
responded by shifting the blame from the situation to her son. "What's the
matter with your boy? Doesn't he sleep well?" Then I asked the father,
"Don't you think your boy can handle this?"
He bristled, "Of course he can -- he's a real tough
kid, a leader." Turning to the mother, he said, "Come on Honey, we've
wasted enough time already." And to me, "See you again at the next
Compare the reactions of these visitors to the reactions of civilians in encounters with the police or other authorities. How typical was their behaviour?
A Mass Escape Plot
The next major event we had to contend with was a rumoured
mass escape plot. One of the guards overheard the prisoners talking about an
escape that would take place immediately after visiting hours. The rumour went
as follows: Prisoner #8612, whom we had released the night before, was going to
round up a bunch of his friends and break in to free the prisoners.
How do you think we reacted to this rumour? Do you think
we recorded the pattern of rumour transmission and prepared to observe the
impending escape? That was what we should have done, of course, if we were
acting like experimental social psychologists. Instead, we reacted with concern
over the security of our prison. What we did was to hold a strategy session
with the Warden, the Superintendent, and one of the chief lieutenants, Craig
Haney, to plan how to foil the escape.
After our meeting, we decided to put an informant (an
experimental confederate) in the cell that #8612 had occupied. The job of our
informant would be to give us information about the escape plot. Then I went
back to the Palo Alto Police Department and asked the sergeant if we could have
our prisoners transferred to their old jail.
My request was turned down because the Police Department would not be covered by insurance if we moved our prisoners into their jail. I left angry and disgusted at this lack of co-operation between our correctional facilities (I was now totally into my role).
Then we formulated a second plan. The plan was to
dismantle our jail after the visitors left, call in more guards, chain the
prisoners together, put bags over their heads, and transport them to a fifth
floor storage room until after the anticipated break in. When the conspirators
came, I would be sitting there alone. I would tell them that the experiment was
over and we had sent all of their friends home, that there was nothing left to
liberate. After they left, we'd bring our prisoners back and redouble the
security of our prison. We even thought of luring #8612 back on some pretext
and then imprisoning him again because he was released on false pretences.
I was sitting there all alone, waiting anxiously for the
intruders to break in, when who should happen along but a colleague and former
Yale graduate student roommate, Gordon Bower. Gordon had heard we were doing an
experiment, and he came to see what was going on. I briefly described what we
were up to, and Gordon asked me a very simple question: "Say, what's the
independent variable in this study?"
To my surprise, I got really angry at him. Here I had a
prison break on my hands. The security of my men and the stability of my prison
was at stake, and now, I had to deal with this bleeding heart, liberal,
academic, effete dingdong who was concerned about the independent variable! It
wasn't until much later that I realised how far into my prison role I was at
that point -- that I was thinking like a prison superintendent rather than a
In an exploratory study such as this, one problem is defining what the "data" are -- the information we should collect. Also, what should have been done to minimise the effects of experimenter bias on the outcome of the study? What were the dangers of the principal investigator assuming the role of prison superintendent?
Paying Them Back
The rumour of the prison break turned out to be just a
rumour. It never materialised. Imagine our reaction! We had spent an entire day
planning to foil the escape, we begged the police department for help, moved
our prisoners, dismantled most of the prison -- we didn't even collect any data
that day. How did we react to this mess? With considerable frustration and
feelings of dissonance over the effort we had put in to no avail. Someone was
going to pay for this.
The guards again escalated very noticeably their level of
harassment, increasing the humiliation they made the prisoners suffer, forcing
them to do menial, repetitive work such as cleaning out toilet bowls with their
bare hands. The guards had prisoners do push-ups, jumping jacks, whatever the
guards could think up, and they increased the length of the counts to several
A Kafkaesque Element
At this point in the study, I invited a Catholic priest
who had been a prison chaplain to evaluate how realistic our prison situation
was, and the result was truly Kafkaesque. The chaplain interviewed each
prisoner individually, and I watched in amazement as half the prisoners
introduced themselves by number rather than name.
After some small talk, he popped the key question:
"Son, what are you doing to get out of here?" When the prisoners
responded with puzzlement, he explained that the only way to get out of prison
was with the help of a lawyer. He then volunteered to contact their parents to
get legal aid if they wanted him to, and some of the prisoners accepted his
The priest's visit further blurred the line between
role-playing and reality. In daily life this man was a real priest, but he had
learned to play a stereotyped, programmed role so well -- talking in a certain
way, folding his hands in a prescribed manner -- that he seemed more like a
movie version of a priest than a real priest, thereby adding to the uncertainty
we were all feeling about where our roles ended and our personal identities
The only prisoner who did not want to speak to the priest
was Prisoner #819, who was feeling sick, had refused to eat, and wanted to see
a doctor rather than a priest. Eventually he was persuaded to come out of his
cell and talk to the priest and superintendent so we could see what kind of a
doctor he needed. While talking to us, he broke down and began to cry
hysterically, just as had the other two boys we released earlier. I took the
chain off his foot, the cap off his head, and told him to go and rest in a room
that was adjacent to the prison yard. I said that I would get him some food and
then take him to see a doctor.
While I was doing this, one of the guards lined up the
other prisoners and had them chant aloud: "Prisoner #819 is a bad
prisoner. Because of what Prisoner #819 did, my cell is a mess, Mr.
Correctional Officer." They shouted this statement in unison a dozen
As soon as I realised that #819 could hear the chanting, I
raced back to the room where I had left him, and what I found was a boy sobbing
uncontrollably while in the background his fellow prisoners were yelling that
he was a bad prisoner. No longer was the chanting disorganised and full of fun,
as it had been on the first day. Now it was marked by utter conformity and
compliance, as if a single voice was saying, "#819 is bad."
I suggested we leave, but he refused. Through his tears,
he said he could not leave because the others had labelled him a bad prisoner.
Even though he was feeling sick, he wanted to go back and prove he was not a
At that point I said, "Listen, you are not #819. You
are [his name], and my name is Dr. Zimbardo. I am a psychologist, not a prison
superintendent, and this is not a real prison. This is just an experiment, and
those are students, not prisoners, just like you. Let's go."
He stopped crying suddenly, looked up at me like a small
child awakened from a nightmare, and replied, "Okay, let's go."
The next day, all prisoners who thought they had grounds
for being paroled were chained together and individually brought before the
Parole Board. The Board was composed mainly of people who were strangers to the
prisoners (departmental secretaries and graduate students) and was headed by
our top prison consultant.
Several remarkable things occurred during these parole
hearings. First, when we asked prisoners whether they would forfeit the money
they had earned up to that time if we were to parole them, most said yes. Then,
when we ended the hearings by telling prisoners to go back to their cells while
we considered their requests, every prisoner obeyed, even though they could
have obtained the same result by simply quitting the experiment. Why did they
obey? Because they felt powerless to resist. Their sense of reality had
shifted, and they no longer perceived their imprisonment as an experiment. In
the psychological prison we had created, only the correctional staff had the
power to grant paroles.
During the parole hearings we also witnessed an unexpected
metamorphosis of our prison consultant as he adopted the role of head of the
Parole Board. He literally became the most hated authoritarian official
imaginable, so much so that when it was over he felt sick at who he had become
-- his own tormentor who had previously rejected his annual parole requests for
16 years when he was a prisoner.
Types of Guards
By the fifth day, a new relationship had emerged between
prisoners and guards. The guards now fell into their job more easily -- a job,
which at times was boring and at times was interesting.
There were three types of guards. First, there were tough
but fair guards who followed prison rules. Second, there were "good
guys" who did little favours for the prisoners and never punished them.
And finally, about a third of the guards were hostile, arbitrary, and inventive
in their forms of prisoner humiliation. These guards appeared to thoroughly
enjoy the power they wielded, yet none of our preliminary personality tests
were able to predict this behaviour. The only link between personality and
prison behaviour was a finding that prisoners with a high degree of
authoritarianism endured our authoritarian prison environment longer than did
Most prisoners believed that the subjects selected to be guards were chosen because they were bigger than those who were made prisoners, but actually, there was no difference in the average height of the two groups. What do you think caused this misperception?
The prisoners even nicknamed the most macho and brutal
guard in our study "John Wayne." Later, we learned that the most
notorious guard in a Nazi prison near
Buchenwald was named "Tom Mix" -- the John Wayne
of an earlier generation -- because of his "Wild West" cowboy macho
image in abusing camp inmates.
Where had our "John Wayne" learned to become
such a guard? How could he and others move so readily into that role? How could
intelligent, mentally healthy, "ordinary" men become perpetrators of
evil so quickly? These were questions we were forced to ask.
Prisoners' Coping Styles
Prisoners coped with their feelings of frustration and
powerlessness in a variety of ways. At first, some prisoners rebelled or fought
with the guards. Four prisoners reacted by breaking down emotionally as a way
to escape the situation. One prisoner developed a psychosomatic rash over his
entire body when he learned that his parole request had been turned down.
Others tried to cope by being good prisoners, doing everything the guards
wanted them to do. One of them was even nicknamed "Sarge," because he
was so military-like in executing all commands.
By the end of the study, the prisoners were disintegrated,
both as a group and as individuals. There was no longer any group unity; just a
bunch of isolated individuals hanging on, much like prisoners of war or
hospitalised mental patients. The guards had won total control of the prison,
and they commanded the blind obedience of each prisoner.
One Final Act of Rebellion
We did see one final act of rebellion. Prisoner #416 was
newly admitted as one of our stand-by prisoners. Unlike the other prisoners,
who had experienced a gradual escalation of harassment, this prisoner's horror
was full-blown when he arrived. The "old timer" prisoners told him
that quitting was impossible, that it was a real prison.
Prisoner #416 coped by going on a hunger strike to force
his release. After several unsuccessful attempts to get #416 to eat, the guards
threw him into solitary confinement for three hours, even though their own
rules stated that one-hour was the limit. Still, #416 refused.
At this point #416 should have been a hero to the other
prisoners. But instead, the others saw him as a troublemaker. The head guard
then exploited this feeling by giving prisoners a choice. They could have #416
come out of solitary if they were willing to give up their blanket, or they
could leave #416 in solitary all night.
What do you think they chose? Most elected to keep their
blanket and let their fellow prisoner suffer in solitary all night. (We
intervened later and returned #416 to his cell.)
An End to the Experiment
On the fifth night, some visiting parents asked me to
contact a lawyer in order to get their son out of prison. They said a Catholic
priest had called to tell them they should get a lawyer or public defender if
they wanted to bail their son out! I called the lawyer as requested, and he
came the next day to interview the prisoners with a standard set of legal
questions, even though he, too, knew it was just an experiment.
At this point it became clear that we had to end the
study. We had created an overwhelmingly powerful situation -- a situation in
which prisoners were withdrawing and behaving in pathological ways, and in
which some of the guards were behaving sadistically. Even the "good"
guards felt helpless to intervene, and none of the guards quit while the study
was in progress. Indeed, it should be noted that no guard ever came late for
his shift, called in sick, left early, or demanded extra pay for overtime work.
I ended the study prematurely for two reasons. First, we
had learned through videotapes that the guards were escalating their abuse of
prisoners in the middle of the night when they thought no researchers were
watching and the experiment was "off." Their boredom had driven them
to ever more pornographic and degrading abuse of the prisoners.
Second, Christina Maslach, a recent Stanford Ph.D. brought
in to conduct interviews with the guards and prisoners, strongly objected when
she saw our prisoners being marched on a toilet run, bags over their heads,
legs chained together, hands on each other's shoulders. Filled with outrage,
she said, "It's terrible what you are doing to these boys!" Out of 50
or more outsiders who had seen our prison, she was the only one who ever
questioned its morality. Once she countered the power of the situation,
however, it became clear that the study should be ended.
And so, after only six days, our planned two-week prison
simulation was called off.
On the last day, we held a series of encounter sessions,
first with all the guards, then with all the prisoners (including those who had
been released earlier), and finally with the guards, prisoners, and staff
together. We did this in order to get everyone's feelings out in the open, to
recount what we had observed in each other and ourselves, and to share our
experiences, which to each of us had been quite profound.
We also tried to make this a time for moral reeducation by
discussing the conflicts posed by this simulation and our behaviour. For
example, we reviewed the moral alternatives that had been available to us, so
that we would be better equipped to behave morally in future real-life
situations, avoiding or opposing situations that might transform ordinary
individuals into willing perpetrators or victims of evil.
In the encounter sessions, all the prisoners were happy the experiment was over, but most of the guards were upset that the study was terminated prematurely. Why do you think the guards reacted this way?
Two months after the study, here is the reaction of
prisoner #416, our would-be hero who was placed in solitary confinement for
"I began to feel that I was losing my identity, that
the person that I called "Clay," the person who put me in this place,
the person who volunteered to go into this prison -- because it was a prison to
me; it still is a prison to me. I don't regard it as an experiment or a
simulation because it was a prison run by psychologists instead of run by the
state. I began to feel that that identity, the person that I was that had
decided to go to prison was distant from me -- was remote until finally I
wasn't that, I was 416. I was really my number."
Compare his reaction to that of the following prisoner who
wrote to me from an Ohio penitentiary after being in solitary confinement for
an inhumane length of time:
"I was recently released from solitary confinement
after being held therein for thirty-seven months. The silence system was
imposed upon me and if I even whispered to the man in the next cell resulted in
being beaten by guards, sprayed with chemical mace, black jacked, stomped, and
thrown into a strip cell naked to sleep on a concrete floor without bedding,
covering, wash basin, or even a toilet....I know that thieves must be punished,
and I don't justify stealing even though I am a thief myself. But now I don't
think I will be a thief when I am released. No, I am not rehabilitated either.
It is just that I no longer think of becoming wealthy or stealing. I now only
think of killing -- killing those who have beaten me and treated me as if I
were a dog. I hope and pray for the sake of my own soul and future life of
freedom that I am able to overcome the bitterness and hatred which eats daily
at my soul. But I know to overcome it will not be easy."
Terminated on August 20, 1971
Our study was terminated on August 20, 1971. The next day,
there was an alleged escape attempt at San Quentin. Soledad brother George
Jackson, who had smuggled a gun into the prison, released prisoners in the
Maximum Adjustment Centre from their cells. Several guards and some informant
prisoners were tortured and murdered during the attempt, but the escape was
prevented after the leader was allegedly gunned down while trying to scale the
30-foot high prison walls.
Less than one-month later, prisons made more news when a
riot erupted at Attica Prison in New York. After weeks of negotiations with
prisoners who held guards hostage while demanding basic human rights, New York
Governor Nelson Rockefeller ordered the National Guard to take back the prison
by full force. A great many guards and prisoners were killed and injured by
that ill-advised decision.
One of the major demands of the prisoners at Attica was
that they be treated like human beings. After observing our simulated prison
for only six days, we could understand how prisons dehumanise people, turning
them into objects and instilling in them feelings of hopelessness. And as for
guards, we realised how ordinary people could be readily transformed from the
good Dr. Jekyl to the evil Mr. Hyde.
The question now is how to change our institutions so that
they promote human values rather than destroy them. Sadly, in the decades since
this experiment took place, prison conditions and correctional policies in the
United States have become even more punitive and destructive. The worsening of
conditions has been a result of the politicisation of corrections, with
politicians vying for who is toughest on crime, along with the radicalisation
of arrests and sentencing, with African-Americans and Hispanics
overrepresented. The media has also contributed to the problem by generating
heightened fear of violent crimes even as statistics show that violent crimes
There are more Americans in jails and prisons -- both men and women -- than ever before in history. According to a recent Justice Department survey, the number of jailed Americans more than doubled during the past 12 years, with over 1.8 million people in jail or prison as of 1998. To learn more about this issue or the Stanford Prison Experiment, please consult the bibliography below.
Zimbardo, P. G., Maslach, C., & Haney, C. (2000).
Reflections on the Stanford Prison Experiment: Genesis, transformations, consquences.
In T. Blass (Ed.). Obedience to
authority: Current Perspectives on the Milgram paradigm (pp.193-237).
Mahwah, N.J.: Erlbaum.
Haney, C., & Zimbardo, P. G. (1998). The past and
future of U.S. prison policy: Twenty-five years after the Stanford Prison
Experiment. American Psychologist, 53,
Zimbardo, P. G. (1994). Transforming California's prisons into expensive old age homes for
felons: Enormous hidden costs and consequences for California's taxpayers.
The Center on Juvenile and Criminal Justice, San Francisco, CA.
Zimbardo, P. G. (1979). (Testimony of Dr. Philip Zimbardo
to U.S. House of Representatives Committee on the Judiciary.) In J. J.
Bonsignore, et al. (Eds.), Before the
law: An introduction to the legal process (pp. 396-399) (2nd ed.). Boston:
Haney, C., & Zimbardo, P. G. (1976). Social roles and
role-playing: Observations from the Stanford prison study. In E. P. Hollander
& R. G. Hunt (Eds.), Current
perspectives in social psychology (4th ed.) (pp. 266-274). New York: Oxford
Zimbardo, P. G. (1974). The detention and jailing of
juveniles (Hearings before U.S. Senate Committee on the Judiciary Subcommittee
to Investigate Juvenile Delinquency, 10, 11, 17, September, 1973) (pp.
141-161). Washington, DC: U.S. Government Printing Office.
Zimbardo, P. G., Haney, C., Banks, W. C., & Jaffe, D.
(1973, April 8). The mind is a formidable jailer: A Pirandellian prison. The
New York Times Magazine, Section 6, 36, ff.
Haney, C., Banks, W. C., & Zimbardo, P. G. (1973).
Interpersonal dynamics in a simulated prison. International Journal of Criminology and Penology, 1, 69-97.
Zimbardo, P. G. (1971). The power and pathology of imprisonment. Congressional Record. (Serial No. 15, October 25, 1971). Hearings before Subcommittee No. 3, of the Committee on the Judiciary, House of Representatives, Ninety-Second Congress, First Session on Corrections, Part II, Prisons, Prison Reform and Prisonerís Rights: California. Washington, DC: U.S. Government Printing Office.
Here are some questions worth considering:
police procedures are used during arrests, and how do these procedures lead
people to feel confused, fearful, and dehumanised?
2. If you
were a guard, what type of guard would you have become? How sure are you?
prevented "good guards" from objecting or countermanding the orders
from tough or bad guards?
4. If you
were a prisoner, would you have been able to endure the experience? What would
you have done differently than those subjects did? If you were imprisoned in a
"real" prison for five years or more, could you take it?
5. Why did
our prisoners try to work within the arbitrary prison system to effect a change
in it (e.g., setting up a Grievance Committee), rather than trying to dismantle
or change the system through outside help?
factors would lead prisoners to attribute guard brutality to the guards'
disposition or character, rather than to the situation?
7. What is
"reality" in a prison setting? This study is one in which an illusion
of imprisonment was created, but when do illusions become real? Contrast
consensual reality and physical or biological reality, and explain the
implications of the following poem (by PGZ):
Within the illusion
Death is the only reality,
is Reality the only death?
Within the reality of imprisonment,
Illusion is the only freedom,
is Freedom the only illusion?
8. What is
identity? Is there a core to your self-identity independent of how others
define you? How difficult would it be to remake any given person into someone
with a new identity?
9. Do you
think lower class, ghetto kids would have broken down in the same emotional way
as did our middle-class prisoners? Why? What about women?
10. After the
study, how do you think the prisoners and guards felt when they saw each other
in the same civilian clothes again and saw their prison reconverted to a
basement laboratory hallway?
beyond physical prisons built of steel and concrete, what psychological prisons
do we create for others and ourselves? If prisons are seen as forms of control
which limit individual freedom, how do they differ from the prisons we create
through racism, sexism, ageism, poverty, and other social institutions? Extend
your discussion to focus on:
The illusion of prison created in marriages where one
spouse becomes "guard" and the other becomes "prisoner"
The illusion of prison created in neurosis where one
aspect of the person becomes the prisoner who is told he/she is inadequate and
hopeless, while another aspect serves as a personal guard
The silent prison of shyness, in which the shy person is
simultaneously his or her own guard and prisoner
12. Was it
ethical to do this study? Was it right to trade the suffering experienced by
participants for the knowledge gained by the research? (The experimenters did
not take this issue lightly, although the Slide Show may sound somewhat
matter-of-fact about the events and experiences that occurred).
13. How do
the ethical dilemmas is this research compare with the ethical issues raised by
Stanley Milgram's obedience experiments? Would it be better if these studies
had never been done?
14. If you
were the experimenter in charge, would you have done this study? Would you have
terminated it earlier? Would you have conducted a follow-up study?
15. How can
we change our real institutions, such as Attica Prison, when they are designed
to resist critical evaluation and operate in relative secrecy from taxpayers
what this research says about the power of prison situations to have a
corrosive effect on human nature, what recommendations would you make about
changing the correctional system in your country?
Why did Zimbardo's prisoners go along with the mock prison?
> Excellent website you have constructed. I found your link to the Zimbardo
> Prison Study which I have studied at college but there is something I'm
> failing to understand. They knew it was an experiment because they gave
> their consent, so why did they not withdraw or question the guards or
> superintendent. They seem to of acted as they had really done something
> wrong prior to the experiment taking place?
> I may have missed something somewhere but this is confusing me and I can't
> fully understand the whole case without it.
> Your help would be most appreciated as I have my A-level psychology exams
> the 6th June
> Thank you
> Name supplied
Thanks for your question, and a tricky one it is to. I am not sure whether
there is just one acceptable answer, but I will give you my opinion anyhow.
A clue to one possible answer comes from an episode in which Zimbardo in a
rare act of compassion allows a prisoner to be sent to hospital, as he is
showing all the signs of a nervous breakdown. As the prisoner is leaving
many of his fellow inmates deride him for failing to fulfil his obligation
to the experiment. This would tell us two things; firstly there would be a
lot of social pressure not to leave the experiment and secondly that many
prisoners felt obliged to put up with the conditions as they had agreed to
participate in the experiment. So we have two good reasons for the
prisoners staying, but I think Zimbardo would be right in asserting that
there is more to it than this. The situation although artificial at one
level of consciousness may have got to them at a subconscious level. The
fact that some got ill and showed symptoms of nervousness to such an extent
that Zimbardo's fiancée was moved to beg him to abandon his experiment well
before the planned two weeks, surely demonstrates how the situation had
affected the participants' psyche. The way that the prisoners and guards
spent most of their free time talking about the prison, also points to how
pervasive the situation had become. The prisoners could have talked about
their past and what they planned to do in a couple of weeks time, and the
guards, having gone home between shifts would have had much to engage
themselves with! So hopefully, you can see that there were a number of
forces acting upon the participants.
All the best for the exams