The Lucifer Effect: Understanding How Good People Turn Evil

Zimbardo’s team holds a Saturday meeting with the guards to explain to them the purpose of the experiment and that the prison would be a metaphor “for the loss of freedom that all of us feel in different ways for different reasons” (54).

The guards were asked to deindividualize the prisoners and to foster a sense of helplessness. Zimbardo’s research centered around power: “What will they do to try to gain power to regain some degree of individuality, to gain some freedom, to gain some privacy?” (55).

As the prisoners are processed, the guards immediately begin to make fun of their genitals. Stockings are placed over the prisoners’ heads to erase markers of their individuality. ID numbers replace their names, and they are expected to memorize their numbers. Prison Guard Arnett barks the rules to prisoners and demands that they memorize all rules. The prisoners respond by laughing as “[t]hey are hardly into playing their role as prisoners—yet” (42).

Zimbardo watches this scene unfold from behind a small scrim-covered window. Due to the cost of tape at the time, he records only snippets of video. Zimbardo acts as the prison superintendent, and his team of psychologists and graduate students perform other roles, such as the warden and the parole board.

After reading the rules to the prisoners, the guards commence “the count” (45). In federal prisons, at the time, five types of counts serve various purposes. In the Stanford Prison, there is only one type of count and its purpose is to establish the guards’ authority and to psychologically diminish and humiliate the prisoners. During counts, prisoners must count-off in increasingly humiliating ways and to perform push-ups and other physical activities.

The prison has been constructed in the basement of Stanford University’s psychology building with cells, a yard, and even solitary confinement. The day shift guards exert their authority, but “[i]t takes a while for the guards to get into their roles” (46), and they are replaced at shift-change by the night shift. Prisoners 819 and 8612 talk back to the night shift guards. Before the warden leaves, he encourages the prisoners to write to friends and family to invite them to visit.

After Warden Jaffe leaves, Guard Hellmann begins his count, which he has adapted into a creative form of torture. Under Hellmann’s command, the night shift guards make prisoners count in multiples and berates them to count faster, count backwards, and even sing the counts. Punishment is doled in the form of push-ups, jumping jacks, and other physical exercises, and the prisoners are punished for no discernable reason or offense. By the end of the night shift, prisoner 8612 is in solitary confinement.

The prisoners can use the toilet only at designated times. By now, prisoners 8612 and 819 have already begun organizing the prisoners to rebel. The prisoners are awoken by the morning shift guards shrieking whistles at 2:30 a.m. The guards yell and begin a count. The prisoners are surprised, exhausted, and angry, feeling the first signs of time distortion.

Zimbardo recalls that while the experiment centered on the powerlessness of the prisoners, he eventually realized the guards themselves were as key to his research as the prisoners. 

The guards wake the prisoners at 6:00 the following morning. During the morning count and exercises, guards begin to exercise more dominance. The guards verbally abuse the prisoners and harass them while they perform exercises and chores. Prisoner 8612 lunges at guard Vandy, and Vandy punches him in the chest before calling for reinforcements. Prisoners 819 and 8612 are thrown in the hole, where they begin plotting a rebellion. The other prisoners violate the rule against talking by discussing a hunger strike and compiling demands: “Previously silent prisoners, including 3401, our only Asian-American participant, now become energized in their open support” (59).

After breakfast, prisoners 7258 and 5486 refuse to return to their cells, but other prisoners in Cell 3 remain well-behaved. The guards interpret the hostility of the prisoners as an indication that the guards have been too lenient so the guards create a morning work routine. The guards punish the prisoners in Cells 1 and 2 by dragging their blankets through the underbrush outside, so the blankets are covered in burrs. The prisoners who have been in the hole are released. A small group of prisoners tear the ID numbers from their uniforms. The guards retaliate by stripping the prisoners naked until their numbers are replaced.

Day-shift guards arrive at 10 o’clock in the morning to find a completely different prison than the one they left the night before. Cell 1 rebels by pushing their beds against the cell door and covering the opening with blankets. To prevent Cell 2 from doing the same thing, the guards rush into the cell and throw their cots into the yard, causing two prisoners to protest by asserting that they are not prisoners, but participants in an experiment. Guard Landry shoots a fire extinguisher into Cell 2. Cell 3 does not join in the rebellion, which gives guard Arnett the idea to reward Cell 3 with special privileges for good behavior. The guards successful quelled the rebellious prisoners, using their behavior “as justification for escalating their dominance and control” (62-63) while the prisoners who rebelled feel pride in themselves for their acts of protest.

The guards prepare a special lunch for Cell 3 and extend time in the hole, which is supposed to be limited to one hour. Zimbardo does not interfere. The prisoners in Cell 1 attempt an escape, which is odd because they can quit the experiment at any time. Guard Landry foils the escape. During the next count, Zimbardo notices that guard Markus is not acting authoritatively and asks Warden Jaffe talk to him about being more authoritative towards the prisoners. Markus responds to Warden Jaffe that “[r]eal-life experience has taught [him] that tough, aggressive behavior is counterproductive” (65).

Prisoner 8612 is destabilizing. He earns increasingly more hole time, and he claims he is feeling sick. He meets with Warden Jaffe and complains that the guards’ behavior is arbitrary and sadistic. Prisoner 8612 becomes enraged and insists “on seeing ‘the fucking Dr. Zimbardo, Superintendent” (67). He meets with Zimbardo and Carlo Prescott, a man recently paroled after serving 17 years in San Quentin State Prison, who is co-teaching classes with Zimbardo and helping with the prison experiment. Prisoner 8612 is very distraught, but Carlo responds to him by “lash[ing] out” (68). Prisoner 8612 demands to be released. By the contract he signed, prisoner 8612 should be released, but Zimbardo pressures him to remain imprisoned, promising conditions will improve if he agrees to snitch on the other prisoners. Prisoner 8612 is escorted back to the prison by Zimbardo, and he tells his fellow prisoners: “I couldn’t get out! They wouldn’t let me out! You can’t get out of here!” (70). The impact of these words on the other prisoners is significant; when the prisoners believe that “they had lost their liberty to quit on demand, lost their power to walk out at will” (71), the prisoner experiment transformed into an actual prison.

As the night progresses, prisoner 8612 begins to lose touch with reality, prisoner 1037 becomes despondent and detached, and other prisoners rebel. Guards Hellman and Burdan increase their harsh treatment of the prisoners in response. As the night progresses, their punishment becomes indiscriminate. The guards become physical, which is against the rules the prisoners agreed to, but neither Zimbardo nor the other psychologists running the experiment step in.

After lights out, prisoner 8612 screams and threatens to do anything necessary to get out, even slit his wrists. Craig Haney, another psychologist involved in the experiment, meets with prisoner 8612 and decides to release him. Zimbardo and the team rationalize this unexpected and early outburst, blaming a “flaw” in their screening process that had failed to reveal the potential of 8612 to destabilize. At this time, they “ignor[e] the other possibility that the situational forces operating in this prison simulation had become overwhelming for him” (78). This rationalization demonstrates that the researchers applied dispositional thinking to their own experiment, the purpose of which is to learn about situational and systemic factors influence over human behavior. 

By Tuesday, “[o]ur prisoners are looking raggedy and bleary-eyed, and our little prison is beginning to smell like a men’s toilet in a New York subway station” (80). Prisoner 8612’s breakdown and his claim that prisoners cannot quit the experiment makes the remaining prisoners despondent. The guards continue to harass prisoners. Zimbardo’s team notices that shorter guards treat prisoners more harshly, even tripping them as they walk down the stairs. Taller guards fall more easily into leadership roles. The same leadership dynamic exists among prisoners. The tallest, prisoner 5704, is becoming a leader among prisoners. Visits are scheduled for Tuesday night, so Zimbardo’s team spend the day “paint[ing] a brighter picture for the parents, friends, and girlfriends” (80), but a rumored break-in by former prisoner 8612 and his friends occupies much of Zimbardo’s attention.

At the morning’s count, the guards establish several new rules aimed at unruly prisoners. Prisoners now must participate in all prison activities, keep their personal effects neat and orderly, maintain spotless floors, and may not “move, tamper with, or deface walls, ceilings, windows, doors, or any other prison property” (83). A new rule is also aimed at the new leader, prisoner 5704, who is the only smoker: Smoking is now a privilege to be rewarded based on good behavior. As the day progresses, Zimbardo notices a deep change within the subjects; the guards appear to have “internalized the hostility, negative affect, and mind-set characteristic of some real prison guards” (86). For example, the guards appear to see themselves as benevolent actors facing the difficult task of keeping a group of unruly, untrustworthy, and unsympathetic prisoners in line. They have quickly begun to depersonalize and dehumanize the prisoners, even blaming them for the unsanitary conditions which they had no part in creating and from which they alone suffer.

Zimbardo has become consumed by prisoner 8612 and the rumored break-in. He contacts the local police about transferring the experiment to the old city jail which is no longer in use; the police rebuke him, voicing concerns regarding potential injury to the students and false imprisonment claims. Zimbardo decides to insert an informant into the prison to gain information, and then move the prisoners to another location. At this point, they will trick the intruders into thinking the experiment has been terminated. Zimbardo later reflects on his actions, referring to himself as a “nutcase,” and describing his state of mind as “irrationally obsessed with the imagined assault on ‘my prison’” (88). Nevertheless, Zimbardo persists in his plan. He places a new prisoner, Dave, into the jail, and Dave quickly notices the paranoia of his fellow prisoners. Soon Dave, the informant, grows distressed over the bathroom routine, befriends his fellow prisoners, and becomes a greater asset to the prisoners than to Zimbardo. Zimbardo’s team, acting as prison administration, meet with disgruntled prisoners, but they do not address their concerns. Prison administrators also undertake the task of making the prison presentable to visitors in preparation for the evening’s visits.

When the visitors arrive, Zimbardo’s team psychologically manipulates them in order to control their behavior as well as the behavior of the prisoners and the guards. Visitors are given a list of rules they must follow, which they obey completely. Zimbardo’s team also pits visitors against the prisoners. For example, they blame the delay on the prisoners taking too long to eat and they invent a visitor limit that supposedly was not communicated to them by prisoners in their invitations. The individual visits are uneventful. The visitors do not violate the prison’s rules and conditions, even when a prisoner informs his parents he is being forced to sleep on the floor. Prisoner 1037’s mother notices that he doesn’t look well. She addresses his health with Zimbardo, but Zimbardo persuades her and her husband that nothing is wrong, though it is obvious even to Zimbardo that prisoner 1037 is malnourished, depressed, and unwell.

After visitation, Zimbardo’s team moves the prisoners to another room and waits for intruders, but none arrive. In hindsight, Zimbardo realizes that at this moment, he and his team had lost “the scientific detachment essential for conducting any research with unbiased objectivity” (99). Zimbardo and the team continue to rationalize the unexpected results, and later, Zimbardo remembers the moment: “We unconsciously looked for scapegoats to deflect blame from ourselves. And we did not have to look far. All around us were prisoners who were going to pay the price for our failure and embarrassment” (99). 

Carlo Prescott, the ex-con who had met with prisoner 8612, and other members of Zimbardo’s team serve on the experiment’s parole board. Father McDermott, a priest who previously worked in a penitentiary, visits the prisoners before their first parole hearing. He meets with every prisoner. Zimbardo is struck by how realistically he behaves, recalling that “Father McDermott himself has slipped deeply into the role of prison chaplain” (102). The prisoners complain about mistreatment and rule violations. Father McDermott advises the prisoners to obtain legal counsel and promises to discuss their cases with lawyers. Father McDermott tells Zimbardo that the prisoners strike him as educated men who do not understand prisons; rather, they resemble “the people you want to try to change the prison system—tomorrow’s leaders and today’s voters—and they are the ones who are going to shape community education” (103).

Prisoner 819 has dark circles under his eyes and uncombed hair sticking out in every direction. He takes his rage out on the contents of his cell, then “breaks down and starts to cry” (104). After a consultation, Zimbardo moves him into a different room so he can have some rest and relaxation. As Zimbardo walks Father McDermott out of the makeshift prison, they hear shouts and chants from the yard; the guards are forcing the prisoners to chant: “Prisoner 819 did a bad thing” (105). Prisoner 819 can hear everything in the R&R room. Zimbardo finds him “hunched over into a quivering mass, hysterical” (107). He insists to Zimbardo that he cannot leave the experiment labeled a “bad prisoner” (107) and abandon his fellow prisoners. Zimbardo reminds him that he is a participant in an experiment, and Prisoner 819 calms down.

Zimbardo’s informer prisoner, Dave, tries to foster resistance among the prisoners, but he becomes dejected when he observes that “everyone was willing to do what they were told” (109), even when their instructions were humiliating. Dave’s personal reflections illustrate the “ powerful force [that] was operating on the minds of the prisoners to suppress group action against their oppression” (110). The prisoners focus inward instead of considering group survival techniques.

Later, a new prisoner replaces prisoner 819. New prisoner 416 immediately observes the tortuous prison conditions and commits to a hunger strike, which becomes an issue for the guards. He later recalls that upon observing the experiment’s conditions, he immediately wanted to quit, but he was informed by his cellmates that he could not quit. He decides to “exhaust the resources of this simulation by being impossible, by refusing all rewards and accepting their punishments” (160).

Guard Hellman throws 416 in the hole and threatens to deprive the other prisoners of visitation if 416 does not eat dinner. Prisoner 416 maintains his hunger strike, so the guards enlist the prisoners in their harassment and force them to loudly bang on the door to the hole and scream at him. All follow the order except for one prisoner named Sarge, who refuses to utter obscenities as a matter of principle. Sarge’s defiance of this order enrages Hellman, who attempts to force him to use obscenities. Hellman, the most sadistic of the guards, rarely employs physical aggression; instead, he dominates the prisoners verbally, fully aware of the exact margin of freedom allowed in his guard role.

Zimbardo returns from dinner to see prisoner 5704 holding a chair on his head while Hellmann yells at Sarge. Prisoner 7258 does push-ups, and 416 is back in the hole. The guards then force prisoner 7258 to play Frankenstein and Sarge to play the Bride of Frankenstein. This forced play-acting develops into a homoerotic game of leapfrog, instigated by the guards. The guard named Burdan ends the game before it progresses further. Hellman repeatedly attempts to force Sarge to harass prisoner 416 with obscenities, but Sarge refuses. Frustrated, Hellman forces Sarge to perform push-ups with three other prisoners on his back. Sarge refuses to give in. Sarge later explains his mindset:

‘When I entered the prison I determined to be myself as closely as I know myself. My philosophy of prison was not to cause or add to the deterioration of character on the part of fellow prisoners or myself, and to avoid causing anyone punishments because of my actions’ (125).

Zimbardo evaluates prisoner 416’s hunger strike, which he believes should have rallied the other prisoners around him. Because prisoner 416 fails to include other prisoners in his planning or reasoning for dissent, the guards are able to convince the other prisoners that 416 is “a ‘troublemaker’ whose obstinance will only result in punishment or loss of privileges” (125). This response is ironic, according to Zimbardo, who regards the guards as the main troublemakers in the prison community. Hellman forces prisoner 416, a frail-statured man, to perform push-ups. Hellmann puts his foot on 416’s back while he performs push-ups. This physical abuse surprises everyone. 

On Wednesday and Thursday, parole hearings are conducted for prisoners deemed eligible. The parole board consists of Carlo Prescott, psychologist Craig Haney, a male graduate student, and a female secretary. Each prisoner has written a statement requesting parole, which is read to the board by sergeant-at-arms Curt Banks, followed by the guards’ statement contesting each prisoner’s parole request. On Wednesday, prisoners Jim-4325, Glenn-3401, Rich-1037, and Hubbie-7258 appear before the board. On Thursday, prisoners Clay-416, Paul-5704, Jerry-5486, and Sarge-2093 appear before the board. The guards contest all the prisoners’ requests, and Carlo Prescott strongly leans into his role as parole board member, berating and insulting the prisoners for their behavior and parole requests. Each prisoner is interviewed and grilled on their behavior.

In his hearing, prisoner 1037 announces that he will forfeit all the pay he has earned in exchange for freedom. This announcement gives Zimbardo the idea to question every parole applicant about whether or not they would make the same choice. Only prisoners 3401 and 2093 would not. This revelation shocks Zimbardo, who notes how much most of young men value release over the money they have earned in “their twenty-four-hour-a-day job as prisoners” (140). Zimbardo mentions that the $15 dollars per day compensation is what initially motivated the volunteers in the first place.

Zimbardo questions the psychological state and the motivations of the prisoners. He notes that they submitted to the guards and that they were willingly led back to the prison in the basement. Zimbardo wonders why the volunteers, while in the presence of “civilians” during the parole board hearing, did not demand their release. The prisoners at this time had this power, but they did not exercise it, revealing that they “had stopped thinking of their experience as just an experiment” (141), and they ceded all power to the parole board.

The parole hearings make three themes apparent. First, the experiment has been able to blur the boundary between simulation and reality for the prisoners. Second, the prisoners’ subservience increases in response to the guards’ increasing domination. In four days, the prisoners have slipped into subservient roles as prisoners, and they have come to believe they are prisoners in a real prison. Third, Carlo Prescott, the ex-con, undergoes a huge character transformation as he shifts from former prisoner to parole board head, from oppressed to oppressor. The shift has a powerful effect on Prescott and causes him to react to the students in ways that surprise him. Prescott reflects on his sense of shame, acknowledging that “‘people become the role they enact’” (152). 

Violence erupts during Thursday’s 7am count. Prisoner 5704 refuses to perform sit-ups, so guard Ceros insists the other prisoners do sit-ups until prisoner 5704 commences. Prisoner 5704 does not acquiesce, so Ceros orders him to the hole. While leading 5704 to the hole, Ceros pushes 5704 against the wall and they scuffle. Prisoner 5704 claims he has hurt his foot in the scuffle, but he is thrown in the hole without seeing a doctor. The guards keep him in the hole through breakfast, and when he is released, the guards must restrain him from hitting Ceros. In reflecting on the incident and his time as a guard, Ceros notes that he felt that he too was a prisoner, but that the prisoners “had more of a choice in their actions” (156) than the guards, whose sense of freedom was false. He adds that “we were all slaves to something in this environment” (156).

At shift change, the guards agree that prisoner 5704 requires special discipline because of his physical attack on the guards. At the 11:30 a.m. count, 5704 is chained to his bed while the other prisoners are forced to perform 70 push-ups as punishment for his actions. The issues with prisoner 5704 and the continued issues with prisoner 316’s hunger strike spur “a domino effect of confrontations” (161). Prisoner 1037 breaks down next, so Zimbardo paroles him. On hearing of prisoner 1037’s parole, prisoner 4325 breaks down when he is not also paroled at the same time.

Zimbardo decides to parole him. The Thursday night guard’s shift report notes the breakdown of prisoner morale. Prisoner 5486 realizes that he has no control over his own behavior.

Zimbardo’s girlfriend, Christina Maslach, a recent PhD recipient in social psychology who is about to begin her career at Berkeley, joins the experiment as a member of the parole board. She sits in Zimbardo’s prison superintendent’s office and observes the experiment for the first time. She is horrified at what she witnesses. She expresses her concern to Zimbardo and his team, and the psychologists erupt in argument. Dr. Maslach storms out of the prison, and Zimbardo runs after her. They argue in the hall of Stanford’s psychology building. Dr. Maslach is adamant that what Zimbardo is doing is “simply wrong” (170) because he is responsible for people’s suffering. By the end of the argument, she is able to persuade Zimbardo that he and every other study participant have internalized destructive prison values which have overtaken their humanitarian values. Zimbardo decides to end the experiment.

When he returns, Zimbardo learns that, while he was away arguing with Dr. Maslach, guard Hellman has been forcing the prisoners to participate in a sexual game in which the prisoners pretended to be camels humping each other.

The prisoners are scheduled to meet with a public defender on Friday, and Zimbardo decides to hold the meeting before terminating the experiment. After the termination of the experiment, Zimbardo’s team will debrief all current and former prisoners by themselves, the guards by themselves, and then both groups together. All participants will also be invited to return in one month to view the videos and discuss the experiment “from a more detached perspective” (175). Zimbardo orders the overnight guards to refrain from a count, and for the first time since the experiment began, the prisoners sleep for nearly six uninterrupted hours.

Tim B., an attorney with the local public defender’s office, who is also prisoner 7258’s cousin, meets with the prisoners, answers their questions, and responds to their concerns about the guards. They discuss their issues with the contract, their inability to leave the prison, and the torment they receive from the guards, which prisoner 416 describes as “injurious behavior” (177). The public defender is startled by Sarge-2093’s account of performing push-ups with three other prisoners on his back, Jerry-5486’s complaint of inadequate and missed meals, and the general lack of supervision by the senior staff. After addressing their concerns and providing legal advice, the public defender rises to leave and prisoner 7258 has an emotional outburst, screaming for help. The public defender, prisoner 7258’s cousin, responds by explaining the limitations of his job.

After the public defender leaves, Zimbardo tells the prisoners that the experiment is over. At first, the prisoners are subdued, but the prisoners soon erupt in elation and embrace each other.

Zimbardo recognizes that his role in the experiment and his power rendered him incapable of seeing the “reality of the destructive impact of the System” (179) he had put into place. He acknowledges that he should have ended the experiment much earlier. Zimbardo describes the “System” as an extensive network of people and their rules, their expectations, and their behaviors; the System can become independent of the people who initially supply its power and it can come to define its own culture. Zimbardo concludes that he should not have played the prison superintendent while also carrying the role of primary researcher; the dual roles created different and conflicting agendas, which led to identity confusion and a lack of objectivity.

During debriefing, the former prisoners express relief and resentment. The prisoners released earlier no longer display negative symptoms of the emotional overload they suffered. The prisoners articulate that their primary issue during the experiment was “the shame inherent in the submissive role they had played” (181). At least one prisoner, Doug-8612, remains angry with Zimbardo for creating a situation in which the prisoners lost control of their behavior and their minds. All former inmates complain of their treatment by the guards. They argue that the guards exceeded the demands of their role in their abuse. They identify the guards who behaved badly, chief among them Hellman, and they mention the “good guards,” who treated them better and helped them. It is noted, though, that even the good guards failed to act to prevent the evil guards from committing atrocities.

Next, the former guards debrief. They present a different viewpoint than the former prisoners. Most are upset the study had been prematurely terminated. Only a few former guards, all of whom are the “good guards” mentioned in the prisoner debriefing, are happy the study is over. Some former guards apologize for their behavior, while others feel justified in their actions “as necessary to fulfill the role they had been given” (183). Zimbardo recalls that he struggled with the guards who did not feel guilt over the role in causing the suffering of others.  

One guard, John Landry, expresses remorse at his inaction. The former guards identify day two’s prisoner rebellion as the point at which their perceptions of the prisoners changed. Several of the guards’ logs reveal that, during the experiment, their authoritarian behavior seeped into their personal lives, influencing how they treated family members at home.

Finally, the former prisoners return to meet their former tormentors, “indistinguishable in their civilian clothes” (184). The joint session is “stiffly polite” (184). The prisoner and guard groups have the same average height, but the prisoners reveal that during the experiment, they perceived the guards as taller. The abused prisoners do not directly confront their abusers.

The most brutal guard, Hellman, states in his logs that he “was conducting experiments on my own on many occasions” (192) during the prison experiment. In an interview, Hellman explains that he wanted to understand the limits of other people: “it surprised me that no one said anything to stop me” (194). In reality, however, prisoners did resist his offenses and rebel, but he and other guards repressed every rebellion, and Zimbardo’s team of prison administrators reinforced their actions. The prisoners did speak up, and they did attempt to unite, but the system convinced them their efforts were hopeless.