I'm sure Philip Zimbardo has done many interesting experiments, but the one that people mean when they refer to the 'Zimbardo Experiment' is the Stanford Prison Experiment. In 1971 Zimbardo (along with others) conducted an experiment to observe the effect of settings on people's behavior. Zimbardo had enlisted the help of 24 college students to act either the part of prison guards or prisoners. The students were assigned to these roles randomly.

On the morning the experiment started, the local Palo Alto police department assisted Zimbardo with the arrests' of the 'prisoner' students. The students were (to their surprise) individually picked up by real police for violating Penal Codes 211, Armed Robbery, and Burglary. They were treated to full police procedure, including handcuffs. When the 'prisoners' arrived at the police station they were formally booked, finger printed, and taken to a holding cell where they were left blindfolded. They were next driven to the "Stanford County Jail", a mock up of a prison in the basement of the Stanford University psychology building. There they were searched, stripped naked, and deloused. They were then given a prison uniform (a smock) and chained at the ankle.

The 'guards' received no training, only being told that this was a serious and possibly dangerous mission, and to deal with it as they saw fit. They were given khaki uniforms, billy clubs, and mirrored sunglasses.

The prisoners had to ask the guards before doing anything, from smoking a cigarettes to going to the bathroom. The guards were told to rouse the prisoners for 'counts' once per guard shift, waking them up from sleep if necessary. During these 'counts' the prisoners were asked for their identification numbers and quizzed on the prison rules. As the experiment went on, the guards spontaneously increased the length of the 'counts' from ten minutes up to over an hour, during which they mocked and ridiculed the prisoners.

"I was pretty surprised at myself... I made them call each other names and clean out the toilets with their bare hands. I practically considered the prisoners cattle, and I kept thinking: 'I have to watch out for them in case they try something'"
-- Guard M

By the second day, the 'prisoners' rebelled, ripping off their identification numbers and barricading themselves inside the cells. This lasted until the morning shift came in, replacing the night shift. The 'guards' acted in force, calling in reinforcements (other 'guards' who were off shift). The guards first used freezing fire extinguisher spray to force the prisoners away from the cell doors. They then broke into the cells, stripped the prisoners naked, and put the ringleaders of the rebellion into solitary confinement.

The 'guards' then set up a 'privileged cell', in which the good 'prisoners' could stay. The privileges included being allowed to keep their beds, wear their uniforms, wash, and eat regularly. The 'guards' next switched the 'prisoners' in the bad cell with the 'prisoners' in the good cell. I'm not sure what they expected to gain with this tactic, but it confused the 'prisoners'. This is apparently not uncommon in real prisons, and is intended to turn the prisoners against each other. Soon the 'guards' were using bathroom privileges (as opposed to a bucket in the cell) and smoking privileges to help control the 'prisoners'.

36 hours after the experiment started, the first 'prisoner' broke down, suffering emotional disturbance, disorganized thinking, uncontrollable crying, and rage. After Zimbardo and the other experimenters convinced themselves that he wasn't faking (why should that matter? The students were supposed to be able to leave the experiment whenever they wanted. They were already getting too wrapped up in the experiment themselves), they let him go.

The next day was the visiting day. The prisoners' families and friends could come and see how the prisoners were doing. The prisoners were shaved and washed, fed a good dinner, and made to clean their cells. Despite some worried parents, all the prisoners stayed.

Next were rumors of an escape plot. The released prisoner was rumored to be coming with helpers to release the prisoners. Instead of studying it, the experimenters took up arms to stop it. It is also at this point that Zimbardo frankly admits that he and the other experimenters were too wrapped up in the experiment. The prisoners were chained, blindfolded, and marched up to a new prison on the fifth floor. When the rescuers arrived, only Zimbardo would be in the basement, and would tell them that the experiment had been canceled. The rescuers never showed up.

The guards were angry. Endless push-ups, jumping jacks, and meaningless repetitive tasks (such as cleaning the toilets) were assigned to punish the prisoners. The situation did not improve, and on the sixth day since the experiment began Zimbardo called an end to the whole thing - 8 days earlier than planned.

This is an incomplete account. For the whole story, check out

http://www.prisonexp.org/slide-1.htm
and
http://www.prisonexp.org/pdf/pirandellian.pdf

For participating in this experiment the students were paid $15.00 a day.

"There are hardly any excesses of the most crazed psychopath that cannot easily be duplicated by a normal kindly family man who just comes in to work every day and has a job to do."

Terry Pratchett, Small Gods

1. Introduction

   This is Philip Zimbardo's (along with Craig Haney, Curtis Banks and David Jaffe) most famous experiment, and a classic staple of Introduction to Psychology classes. In short, it was a study of human behavior within prisons, both that of prisoner and guard alike.

   Aside from being one of the most fascinating experiments of human psychology, it spurred an enormous ethical debate on the proper procedure of psychology experiments, and caused a "standardization" of experimentation that is safe for the test subject.

   This research was conducted in 1971 and sponsored by the Office of Naval Research, and the results were of interest to the Navy and Marine Corps. The study was to facilitate a better understanding of "basic psychological mechanisms underlying human aggression" (in English: why people can be little bastards), in particular within closed environments where many people are in close contact for very long periods of time (i.e., prison).

   At the time of the experiment, it was becoming blatantly clear that prisons did not deliver the results the government were hoping for: not only were they expensive to maintain, but they did not seem to be much of a deterrent towards crime; many of those thrown into jail simply seem to go back in again and again. This was not the kind of rehabilitation the government was hoping for.

   One of the more popular theories at the time to explain why the whole prison thing wasn't working out was the dispositional hypothesis: "the state of the social institution of prison is due to the 'nature' of the people who administrate it, or the 'nature' of the people who populate it, or both." In other words, prisons are just full of people who aren't entirely normal in the first place. That is, the main cause of the inhumane conditions of a prison can "be traced to some innate or acquired characteristic of the correctional and inmate population."

   If you haven't noticed, it's a theory that sits the fence and does double duty: it caters to the people who think that all prisoners are evil criminals who aren't and were never normal in the first place, and it caters to the people who think that the correction officers/guards are mistreating the prisoners because they weren't all that great at this 'rehabilitating' thing in the first place. Basically.

   Zimbardo basically proved them both wrong.

2. Preparation

   1. Selection

      A small newspaper advertised the experimental study in 1971:

      Male college students needed for psychological study of prison life. $15 per day for 1-2 weeks beginning Aug 14. For further information & applications, come to Room 243, Jordan Hall, Stanford U.

      text of newspaper ad
      transcribed from photo at http://www.prisonexp.org

      Over 70 applicants signed up to make history. They signed the consent form for the experiment, which noted that the study would involve a "loss of privacy". Although the researchers allowed for participants to leave, they would only be allowed to leave either through "established procedures" (as noted in the Prison Life Study: General Information sheet) or for "reasons of health" (as noted in the Consent Form). It is interesting to take note that it was never explicitly stated that they could leave if they so chose. It was, after all, an experiment.

      The applicants were given a battery of tests to determine their personality, background, attitude toward psychopathology, and whether or not they had a criminal background. They were also interviewed. Out of the 70, 24 were chosen, judged "to be the most stable (physically and mentally), most mature, and least involved in anti-social behaviors." Basically, they were considered to be "normal-average", your everyday average joe.

      The standard profile for these 24 men was fairly uniform: healthy, middle-class, Caucasian (there was one exception: one was an 'Oriental', which I'm assuming means Asian). They were all complete strangers, to prevent possible additional variables (such as friendship, cooperation, etc.) from tainting the experiment.

      On the flip of the coin, the chosen were divided into two groups: the prisoners and the guards.

      1. Prisoner

         Those assigned to be a prisoner were called and told to be available at home on Sunday. That was basically about all the warning they were given.

         Once they were chosen (several were on stand-by at home due to the small size of the prison), prisoners were given a list of rules that they were expected to memorize. Their uniform was a muslin smock with an identification number, a chain and lock around an ankle, rubber sandals, and a cap.

         Aside from clothing, prisoners were given a toothbrush, soap, soapdish, towel, and linen.

         If you haven't noticed, they were not given any underwear of any sort. This made the prisoners sit and move very oddly (girlishly), and that, on top of the vaguely dress-like nature of the smock, made them appear very feminine.

      2. Guard

         Those assigned to be guards were sent to a one-day orientation before the prisoners came. They were introduced to the "Superintendent" (Philip Zimbardo) and the "Warden" (David Jaffe). To a certain degree, they were all told to "maintain the reasonable degree of order within the prison necessary for its effective functioning." They were given no other restrictions aside from refraining from physical abuse.

         The participants were to work an 8 hour shift around the clock, with someone coming in at the end of one person's shift, in groups of three. Also, they were to write shift reports daily, concerning the prisoners and the guards. The orientation was capped off with the future guards putting the finishing touches on the prison, including drawing up the rules for the prisoners.

         The guard uniform was made up of khaki shirts and trousers. Instead of basic necessities, the guards were instead outfitted with accessories: a whistle, police batons, and reflective sunglasses.

         The sum effect is that the guards looked very much like police, perhaps, or soldiers; 'manly' and 'disciplined' might be the best adjectives.

         It is interesting to note that many of the guards believed that the study was about the behavior of the prisoners rather than that of the guards. This may have inspired the idea that they were merely role-playing to fulfill a function.

   2. Prison

      1. Physical Aspects

         The prison they used was a converted basement floor within the campus, specifically the psychology building. They split the floor into three parts, separated by a partition: the cell block, the observation room, and the "yard".

         The cell block contained the cell rooms: three small cells were converted from laboratory rooms and furnished with a cot containing a mattress, sheet, and pillow.

         The cell block also contained a single solitary confinement room: a converted closet. At 2' x 2' x 7', there was just enough room to accomodate one person standing up.

         In an adjacent wing, there were the guard's quarters: rooms to change and relax in. They also contained the "bedrooms" of the warden Jaffe and the superintendent Zimbardo.

         As you can see, the researchers did the best they could to make the prison as, well, prisonlike as possible. Their goal? To inspire in the guards and prisoners, respectively, "feelings of power and powerlessness, of control and oppression, of satisfaction and frustration, of arbitrary rule and resistance to authority, of status and anonymity, of machismo and emasculation." A tall order, but they succeeded. Beyond their wildest dreams.

      2. Operational Aspects

         The guards were rotated every 8 hours to watch the prisoners 24 hours, in groups of three. At every rotation, there was a roll call for every prisoner, which served as grounds for a) making sure the prisoners were there and b) they knew the rules.

         Two visiting periods per week were allowed where parents and friends could visit. Certain privileges were issued to the prisoners: three bathroom visits per day, letter-writing, reading, and periods in which they could exercise or watch movies.

         Over time, many of these rights were forgotten or abandoned all together.

3. And It Starts

   1. The Chronology

      With the cooperation of the Palo Alto police department, the researchers started their experiment on a sunny day by arresting nine 'prisoners' at home on a Sunday under charges of Armed Robbery (Penal Codes 211) and Burglary (Penal Codes 459). They were told of their constitutional rights, searched while spread-eagled against the car, cuffed, and then taken to the police station.

      At the police station, things proceeded normally, as they did, for suspects convicted of a felony. Fingerprinted, identified, and left in a jail cell detention, the 'convict' was then moved into the "Stanford County Prison" where the real work began. The prisoner was then stripped naked, issued a uniform, given bare necessities, and, most humiliating of all, de-loused.

      After the rough but not particularly painful handling, the prisoners were introduced to the warden, who made a little speech and handed out the prisoner rules. The prisoners were expected to memorize them.

      Then everything fell apart.

      Note: the events and days it happens on are approximate. All papers - and the website, unfortunately - don't explicitly say what happens on any given day and had to be pieced together by me. There are some contradictions to his papers.

      1. Day 1

         Day 1 passes with little incident. Both the prisoners and the guards probably thought this was one big joke. Still, sitting inside a prison all day must get to you...

      2. Day 2

         A rebellion breaks out. Prisoners assert their identity and barricade themselves in the cells, taunting the guards. The morning shift guards come in, gets upset at the night shift guards for not really doing anything, and decide to use force. They call in three guards from stand-by while the night shift three decide to stay overtime (for a total of 9 guards), and then use a fire extinguisher to force prisoners away from the doors. They strip the prisoners, remove the beds from the cells, and throw the ringleader into solitary confinement. This is when the real harrassment by the guards begin.

         Physical force is all fine and dandy, but hell, six guards were not getting paid for this additional labour. So they switch tactics from physical to mental. The guards make one cell a "special" cell and the three least involved in the rebellion get to go back in, clothes and all, with the privilege of being allowed to be clean. A bit later, they switched prisoners around, so that the "bad" prisoners went to the "good" cell, which resulted in the prisoners not knowing what to expect and who to trust.

         About 36 hours in, Prisoner #8612 breaks down and scares the hell out of the other prisoners by screaming, crying, and telling them that there was "no way out". Researchers think he's faking so he can get out of the experiment and release him with extreme reluctance.

         Interestingly enough, all the 'rights' as asserted in the prisoner rights sheet are turned into 'privileges' by the guards. Eating, sleeping, going to the bathroom, talking, smoking - all these turn into 'privileges'. The time to watch movies and read are cancelled by the guards until further notice.

      3. Day 3

         Visiting day for parents! Prisoners are dressed and cleaned to look presentable for parents. Like it's all one big happy family. They even have dinner and music!

         A rumor spreads around: Another rebellion, this time led by the released prisoner 8612 (who 'obviously' faked his emotional disturbance). 8612 was planning on storming the jail cell with his allies and releasing the prisoners. The staff overreacts, plants an informant into 8612's old cell to get the details, tries to move the prisoners/experiment into Palo Alto's police department's old jail cell (a city official raised a ruckus about liability/insurance, so the police department turned the request down), and instead haul all the prisoners into a storage room for the meantime. They also hatch a plot to bring 8612 back into jail if and when he came back for the other prisoners, under the pretext of him lying about the emotional outburst the day before.

         Needless to say, nothing happens. The guards notice the ruckus and harassment increases. Prisoners are forced to do pushups and jumping jacks for hours; they are also forced to clean toilets with their bare hands.

         A priest comes to visit the prisoners. Acting like a stylized representation of a priest, he chides the prisoners for not getting a lawyer (after all, prisoners have rights, too). Prisoner 819, who refuses to see the priest, breaks down when confronted by Zimbardo and Jaffe and has to be released. He initally refuses to go when the other prisoners are forced to chant "819 is a bad prisoner. Because of what 819 did to prison property we all must suffer. 819 is a bad prisoner." Because of this, he must be told that he was not really a prisoner, but just another college student in an experiment before he is persuaded to leave.

         A second prisoner also breaks down and is released. (Note: this prisoner might been released on either day 3, 4, or 5, but seems most likely on day 3 or early day 4 before the parole board shows up.)

      4. Day 4

         A parole board hearing is set up for the prisoners. When the remaining prisoners are asked if they are willing to forfeit the wages to be freed, the majority say yes.

         The parole board turns down parole for one particular prisoner, which triggers a psychosomatic rash over the prisoner's body. He is then released.

         A stand-by prisoner is then introduced. (Note: this either happens on day 4 or early day 5.) Prisoner 416 (the new prisoner), unused to the brutality, goes on hunger strike. The guards use extreme tactics to get him to eat: they throw him into solitary confinement; instead of helping him when given the option to by the guards, the other prisoners label him a troublemaker and offer no help.

      5. Day 5

         Another prisoner breaks down and has to be released.

         Early that evening, visiting parents ask the superintendent (Zimbardo) to contact a lawyer to get their son out of prison.

      6. Day 6

         A lawyer comes in, on request of Zimbardo, to interview the prisoners with standard questions (however, he is fully aware of the experiment).

         At this point in time, the experiment is cancelled prematurely by Zimbardo.

   2. Reality vs. Fiction

      Within the span of a few short days, it clearly no longer became just a 'game', either to the prisoners, guards, or even researchers, and the fiction blurred into reality:

      1. Abuse: Abuse to the prisoners, either physical or verbal, was heightened during the periods when the guards felt that the researchers were not watching, such as on the way to and from the toilet (which was out of range of the recording equipment). Because physical abuse was not allowed, guards resorted to verbal abuse and tedious exercises. Jumping jacks, pushups (with the guards or other prisoners sitting on top), and other military-like discipline was used. Other, more subtle, ugly exercises were used: after the guards dragged all the blankets into a thorny bush, the prisoners were then forced to take out all the thorns so they could use the blanket to sleep.

         The level of the abuse did not fluctuate from day to day; rather, the level of aggression increased from day 1 to day 6. The new prisoner, thrown into 'jail' towards the end of the experiment, was probably very shocked at the brutality, and still retaining some level of individuality, uses his hunger strike as a weapon that he would probably not have used had he been there from the beginning of the experiment.

         One particularly sadistic guard was nicknamed "John Wayne" for his macho cowboy attitude and reckless disregard for the welfare of the prisoners.

         "I was surprised at myself. . . I made them call each other names and clean the toilets out with their bare hands. I practically considered the prisoners cattle, and I kept thinking: 'I have to watch out for them in case they try something.'"

         Guard M,
         "The mind is a formidable jailer: A Pirandellian Prison"
         (full citation below)

      2. Conversations: Approximately 90% of all conversations during the experiment were about prison life. Very little personal information was exchanged. Talk centered around things like "problem prisoners", the harassment by the guards, food, etc.

      3. The Researchers: When confronted with the rumors of the first releasee coming back to free the other prisoners, the researchers overreacted, even to the point of considering about dragging the first releasee back into the experiment to continue.

         Zimbardo has an interesting personal anecdote from this day; when a college professor comes to visit him and asks jokingly about the experiment's independent variable of the day, Zimbardo nearly loses his temper.

         "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!"

         Philip Zimbardo
         http://www.prisonexp.org

         It is not until then that Zimbardo realizes that he lost himself in the role of "superintendent of a prison" completely.

      4. Incentive: When the prisoners were questioned by the 'parole board' if they would give up the wages they already earned to be freed, three of the five prisoners said yes. Do note that this is the original incentive for the experiment. And yet, when told that this would have to be discussed, the prisoners allowed themselves to be escorted back into the cell instead of simply walking out of the experiment. I doubt they saw any other choice.

         I would like to note that though Zimbardo's papers emphasized this particular aspect as being an amazing thing, nowhere among the forms I've seen make it clear that you can walk out of the experiment, even though it's implied when you think about it. This is an educated guess, but I believe that this might have been one of the factors for the ethics controversy that surrounded this experiment, and possibly the reason why nowadays, when participating in an experiment, it is made absolutely clear you can walk out.

      5. The Parents: During the course of the experiment, two visiting periods occurred where family and friends were allowed to visit. Those visiting were told that they were guests and had to register, wait, be limited to a 10-minute visitation right (instead of the original hour), be under surveillance, and discuss the prisoner's case with the warden. Did they protest? Of course they did.

         How they protested is the key. The ones who were clearly concerned merely asked (privately) the superintendent to make conditions better for the prisoners. They worked within the system given to them, allowed the reality of the experiment to dominate their own.

      6. The Chaplain: The grievance committee (made up of some of the prisoners) demanded a chaplain, and it was given. When the chaplain (a former prisoner chaplain) was introduced, he found that the prisoners introduced themselves by their prison number, rather than name.

         The chaplain proceeded to confuse the hell out of everyone by criticizing the actions of each inmate: why didn't they get a lawyer? Why didn't they appeal for bail? A few prisoners asked him to help them, to contact their parents to arrange for the procurement of a lawyer. After the chaplain leaves, he apparently does call their parents and suggest it.

         The parents, falling readily into the role, call a public defender! For what crime?

   3. Metamorphosis

      The irony behind the guards' sudden change in disposition is best appreciated when you find that many of them described themselves "pacifists or Vietnam War 'doves'". It's startling, and almost painful to watch the change of one guard within a mere six days:

      Before the Experiment

      "As I am a pacifist and nonaggressive individual I cannot see a time when I might guard and/or maltreat other living things."

      ... to the first day ...

      "Feel sure that the prisoners will make fun of my appearance and I evolve my first basic strategy - mainly not to smile at anything they say or do which would be admitting it's all only a game . . . At cell 3 I stop and setting my voice hard and low say to 5486, 'What are you smiling at?' 'Nothing, Mr. Correctional Officer.' 'Well, see that you don't.' (As I walk off I feel stupid.)"

      ... to the third day ...

      "After warning the prisoners not to make any complaints unless they wanted the outside visit terminated fast, we finally brought in the first parents. I made sure I was one of the guards on the yard, because this was my first chance for the type of manipulative power that I really like - being a very noticed figure with almost complete control over what is said or not. While the parents and prisoners sat in chairs, I sat on the end of the table dangling my feet and contradicting anything I felt like. This was the first part of the experiment I was really enjoying . . . 817 is being obnoxious and bears watching."

      ... to the fifth day ...

      "I harass 'Sarge' who continues to stubbornly overrespond to all commands. I have singled him out for special abuse both because he begs for it and because I simply don't like him. The real trouble starts at dinner. The new prisoner (416) refuses to eat his sausage . . . we throw him into the Hole ordering him to hold sausages in each hand. We have a crisis of authority; this rebellious conduct potentially undermines the complete control we have over others. We decide to play upon prisoner solidarity and tell the new one that all the others will be deprived of visitors if he does not eat his dinner. . . I walk by and slam my stick into the Hole door . . . I am very angry at this prisoner for causing discomfort and trouble for the others. I decided to forcefeed him, but he wouldn't eat. I let the food slide down his face. I didn't believe it was me doing it. I hated myself for making him eat but I hated him more for not eating."

      Guard A's diary, quoted from
      "The mind is a formidable jailer: A Pirandellian Prison"
      (see below for full citation)

4. Outcome

   1. Day 6

      "Guilt was the grease in which the wheels of authority turned."

      Terry Pratchett, Small Gods

      The two week experiment was prematurely terminated after six days due to the shocking breakdowns of the prisoners and the increasingly inhumane treatment by the guards.

      That's the standard reason. The website is one of the few places where they briefly also admit the other reason: that someone else prompted the cancellation. Truth is, it's probably more truthful to say that the researchers and professors got caught up in the whole Kafkaesque reality of the experiment and just never thought of stopping. Or perhaps had other pressing reasons to not stop the experiment.

      Towards the end of the fifth day, Professor Christina Maslach stepped in to take a look at the research her lover (Philip Zimbardo) was doing. At first, it bored her; there didn't seem to be anything much going on, so she chatted with one of the guards who was coming in for his shift. She found him "charming, funny, smart".

      You can imagine her surprise when she found out that he was the guard nicknamed John Wayne, one of the most sadistic guards within the group. She watched the guards take prisoners to the bathroom with paperbags over their heads, watched as 'John Wayne' deliberately tripped a prisoner all for the sake of 'role-playing' (when the prisoner accused him of tripping him out of sheer maliciousness, that was his reply) and was instantly nauseous. Her uneasiness was met with teasing by the others.

      Later that night, she exploded at Zimbardo and started up a terrific fight: "I think it is terrible what you are doing to these boys!"

      Zimbardo called off the experiment the next day, only acknowledging that "she challenged us to examine the madness she observed, that we had created and had to take responsibility for." In his papers, he admits that only one professor dared voice any objection to the experiment; though he leaves her name out, it was probably for professionalism (they were, after all, a couple).

      Some call her a hero for doing it, but the good professor points out that a) she had no real investment in this research (no motivation to have this experiment to continue) and b) she came into the experiment very late and was not acclimatized to the brutality between the guards and prisoners. Still, food for thought.

   2. The Test Subjects

      After the experiment was over, everyone was rounded up to have long discussions over what happened and, hopefully, to put bad feelings behind. Which may or may not have been the case.

      Possibly one of the more shocking things to come out of it was that a few guards were disappointed with the cancellation, either a) because they were no longer making the $15/day as promised by the experiment and/or b) they no longer were in a position of power. Evidence suggest highly to the latter; not only were guards never late to work and always showed up, many of them put in additional hours and did overtime for no additional pay. The prisoners were not the only ones who noticed the disappointment; the guards, too, noticed: "The experiment is over. I feel elated but am shocked to find some other guards disappointed somewhat because of the loss of money and some because they are enjoying themselves."

   3. In an Interesting Twist of Fate

      Prisoner #416, one of the five prisoners to break down in the experiment, was so changed by this that he eventually went on to become a forensic psychologist and prison counselor for the San Francisco county jail.

      "John Wayne" became a real estate broker.

      Craig Haney, one of the principal researchers in this experiment, became a lawyer in the field of prisoner litigation.

   All in all, the experiment showed the amazing adaptability of man in any given situation, which was - and still is - often viewed as a Good Thing.

5. Irony is When...

   Attica happens a month later.

6. Conclusion

   Humans never cease to amaze me. And scare me.