And they tell him, "It's a war zone. Do your job. Do whatever you have to do."

He [complained] to higher-ups on the record, "We have mentally ill patients who cover themselves with [excrement]. We have people with tuberculosis that shouldn't be in this population. We have kids mixed with adults."

Zimbardo: Abu Ghraib was under bombardment all the time. In the prison, five soldiers and 20 Iraqi prisoners get killed. That means automatically any soldier working there is under high fear and high stress. Then the insurgency starts in 2003, and they start arresting everyone in sight. When Chip Frederick [starts working at Abu Ghraib] in September, there are 200 prisoners there. Within three months there's a thousand prisoners with a handful of guards to take care of them, so they're overwhelmed. Frederick and the others worked 12-hour shifts. How many days a week? Seven. How many days without a day off? Forty. That kind of stress reduces decision-making and critical thinking and rationality. But that's only the beginning.

Wired: You were an expert defense witness in the court-martial of Sgt. Chip Frederick, an Abu Ghraib guard. What were the situational influences in his case?

Understanding the reason for someone's behavior is not the same as excusing it. Understanding why somebody did something — where that why has to do with situational influences — leads to a totally different way of dealing with evil. It leads to developing prevention strategies to change those evil-generating situations, rather than the current strategy, which is to change the person.

Situations can be sufficiently powerful to undercut empathy, altruism, morality and to get ordinary people, even good people, to be seduced into doing really bad things — but only in that situation.

Philip Zimbardo: No. People are always personally accountable for their behavior. If they kill, they are accountable. However, what I'm saying is that if the killing can be shown to be a product of the influence of a powerful situation within a powerful system, then it's as if they are experiencing diminished capacity and have lost their free will or their full reasoning capacity.

Wired: Your work suggests that we all have the capacity for evil, and that it's simply environmental influences that tip the balance from good to bad. Doesn't that absolve people from taking responsibility for their choices?

He spoke with Wired.com about what Abu Ghraib and his prison study can teach us about evil and why heroes are, by nature, social deviants.

Zimbardo conducted a now-famous experiment at Stanford University in 1971, involving students who posed as prisoners and guards. Five days into the experiment, Zimbardo halted the study when the student guards began abusing the prisoners, forcing them to strip naked and simulate sex acts.

The Abu Ghraib prison made international headlines in 2004 when photographs of military personnel abusing Iraqi prisoners were published around the world. Seven soldiers were convicted in courts martial and two, including Specialist Lynndie England, were sentenced to prison.

In March 2006, Salon.com published 279 photos and 19 videos from Abu Ghraib, one of the most extensive documentations to date of abuse in the notorious prison . Zimbardo claims, however, that many images in his video — which he obtained while serving as an expert witness for an Abu Ghraib defendant — have never before been published.

Zimbardo will speak Thursday afternoon at the TED conference, where he plans to illustrate his points by showing a three-minute video, obtained by Wired.com, that features many previously unseen photographs from the Abu Ghraib prison in Iraq (disturbing content) .

This article has been reproduced in a new format and may be missing content or contain faulty links. Contact wiredlabs@wired.com to report an issue.

As an expert witness in the defense of an Abu Ghraib guard, Philip Zimbardo had access to many imagesof abuse taken by the guards. His TED presentation puts together a short video of some of the unpublished photos, with sound effects added by Zimbardo. Many of the images are explicit and gruesome, depicting nudity, degradation, simulated sex acts and guards posing with corpses. Viewer discretion is advised.

Wired: How did what happened at Abu Ghraib compare to your Stanford prison study?

Zimbardo: The military intelligence, the CIA and the civilian interrogator corporation, Titan, told the MPs [at Abu Ghraib], "It is your job to soften the prisoners up. We give you permission to do something you ordinarily are not allowed to do as a military policeman — to break the prisoners, to soften them up, to prepare them for interrogation." That's permission to step across the line from what is typically restricted behavior to now unrestricted behavior.

In the same way in the Stanford prison study, I was saying [to the student guards], "You have to be powerful to prevent further rebellion." I tell them, "You're not allowed, however, to use physical force." By default, I allow them to use psychological force. In five days, five prisoners are having emotional breakdowns.

The situational forces that were going on in [Abu Ghraib] — the dehumanization, the lack of personal accountability, the lack of surveillance, the permission to get away with anti-social actions — it was like the Stanford prison study, but in spades.

Those sets of things are found any time you really see an evil situation occurring, whether it's Rwanda or Nazi Germany or the Khmer Rouge.

Wired: But not everyone at Abu Ghraib responded to the situation in the same way. So what makes one person in a situation commit evil acts while another in the same situation becomes a whistle-blower?

Zimbardo: There's no answer, based on what we know about a person, that we can predict whether they're going to be a hero whistle-blower or the brutal guard. We want to believe that if I was in some situation [like that], I would bring with it my usual compassion and empathy. But you know what? When I was the superintendent of the Stanford prison study, I was totally indifferent to the suffering of the prisoners, because my job as prison superintendent was to focus on the guards.

As principal [scientific] investigator [of the experiment], my job was to care about what happened to everybody because they were all under my experimental control. But once I switched to being the prison superintendent, I was a different person. It's hard to believe that, but I was transformed.

Wired: Do you think it made any difference that the Abu Ghraib guards were reservists rather than active duty soldiers?

Zimbardo: It made an enormous difference, in two ways. They had no mission-specific training, and they had no training to be in a combat zone. Secondly, the Army reservists in a combat zone are the lowest form of animal life within the military hierarchy. They're not real soldiers, and they know this. In Abu Ghraib the only thing lower than the army reservist MPs were the prisoners.

Wired: So it's a case of people who feel powerless in their lives seizing power over someone else.

Zimbardo: Yes, victims become victimizers. In Nazi concentration camps, the Jewish capos were worse than the Nazis, because they had to prove that they deserved being in this position.

Wired: You've said that the way to prevent evil actions is to teach the "banality of kindness" — that is, to get society to exemplify ordinary people who engage in extraordinary moral actions. How do you do this?

Zimbardo: If you can agree on a certain number of things that are morally wrong, then one way to counteract them is by training kids. There are some programs, starting in the fifth grade, which get kids to think about the heroic mentality, the heroic imagination.

To be a hero you have to take action on behalf of someone else or some principle and you have to be deviant in your society, because the group is always saying don't do it; don't step out of line. If you're an accountant at Arthur Andersen, everyone who is doing the defrauding is telling you, "Hey, be one of the team."

Heroes have to always, at the heroic decisive moment, break from the crowd and do something different. But a heroic act involves a risk. If you're a whistle-blower you're going to get fired, you're not going to get promoted, you're going to get ostracized. And you have to say it doesn't matter.

Most heroes are more effective when they're social heroes rather than isolated heroes. A single person or even two can get dismissed by the system. But once you have three people, then it's the start of an opposition.

So what I'm trying to promote is not only the importance of each individual thinking "I'm a hero" and waiting for the right situation to come along in which I will act on behalf of some people or some principle, but also, "I'm going to learn the skills to influence other people to join me in that heroic action."