A guard comes into a prisoner’s cell at three in the morning and tells him to take off his clothes. He takes away the prisoner’s mattress, tells him that he will no longer be allowed to use the bathroom and hands him a bucket. In the next cell, one defiant and naked prisoner is taken away to solitary confinement as he screams at his guards.

This is not a concentration camp or a political prison. The guards and prisoners are sitting in the basement of a Stanford University building and are participants in a psychology study.

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This summer marked two important anniversaries for Yale’s Psychology Department. The Stanford prison experiment, conducted by Yale graduate and former lecturer Philip Zimbardo GRD ’59, took place 40 years ago, while the Milgram experiment, led by Yale professor Stanley Milgram on campus, marked its 50th anniversary this year. The experiments, both of which are considered landmark social psychology studies, are known for their controversial approach to ethics and for what they suggest about the nature of good and evil inside humans: that people are not as good as they think they are.

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The studies — which have been noted for decades as two of psychology’s least-ethical experiments — were both produced by Yale-affiliated researchers, and one might ask if the climate in the Yale Psychology Department had an impact on the ethically questionable decisions that led to them. As a result of these two projects, regulations for experiments involving human subjects have been revised and reformed nationwide.

“Both of [these studies] have become mythic, almost classic experiments of the way that psychologists go wrong,” said Naomi Rogers, associate professor of history of science and medicine. “I think that they continue to have a lot of power as experiments, as crucial parts to understanding psychology and American history.”


Milgram and Zimbardo knew each other in a professional capacity from their shared time in Yale’s Psychology Department in the late 1950s and early 1960s, Zimbardo said.

Reginald Shepps GRD ’62, who took a course with Milgram as a graduate student, said that around this time, the culture surrounding experimentation in laboratories was more relaxed than it is today.

“This was a time lacking sensitivity for the subjects of psychological experiments and the ethical need to be respectful of the subject’s rights,” Shepps said.

But the lack of emphasis on ethics was not detrimental to the department’s success, Shepps said, noting that regardless of his study’s ethical issues, Milgram is probably one of the top 10 social psychologists of all time in his opinion. University of California, Davis psychology professor Alan Elms, who worked closely with Milgram, agreed and said the Yale Psychology Department of Zimbardo and Milgram’s days was “a collection of brilliant individuals.”

Rogers noted that in the 1970s, political and social demands became more prominent in research, which led to the stricter regulations that are in place now.

“A consequence of both studies is that these research can never be done again in an academic setting,” Zimbardo said. “It eliminates a whole range of behavioral research — these studies are more interesting to people now because they’re an ethical time capsule.”

Indeed, while Elms said many researchers would like to examine some of the questions raised by Milgram’s and Zimbardo’s studies, he added that follow-up work on these fronts is “largely impossible” due to revised APA standards.


In Milgram’s experiment, which began in July 1961 in Linsly-Chittenden Hall, researchers instructed study participants to deliver stronger and stronger electrical shocks to a “victim,” in actuality a nearby actor, in an attempt to determine how obedient to authority the participant were.

Psychologists at the time expected few participants to continue following orders after the “screams” of the “victim” heightened. But over the course of the experiment, approximately two-thirds of the participants continued to shock the “victim” to the maximum voltage.

Former School of Forestry & Environmental Studies professor Herb Weiner, who was a participant in Milgram’s experiment, was in the minority that refused to deliver what it believed to be high-voltage shocks.

“I refused, which was an extremely stressful decision because I was a reasonably obedient student, a reasonably obedient child and a very obedient member of the U.S. Army in World War II, so I know about obedience and how essential it is,” Weiner said. “Afterwards, I went to Stanley Milgram and I told him that he had no business imposing that kind of stress on people who hadn’t been prescreened.”

Opinions were divided within the Psychology Department as to whether the study was ethical.

Only one Yale faculty member was critical enough of the ethical issues surrounding Milgram’s study to submit a complaint to the American Psychological Association, Elms said.

Elms said that in his opinion the ethics of Milgram’s experiment were sound.

“From the outset, I was quite impressed with Milgram’s concerns about research ethics,” Elms said. “He was one of the first researchers to include a debriefing at the end of the experiment to explain that the apparent “victim” of electric shocks did not actually get harmed.”

But Shepps said he thought Milgram’s experiment generated more controversy on campus than Elms suggests.

“When news spread about what [Milgram] was doing, eyebrows were raised in the department about how ethical it was,” Shepps said. “After I finished the course, controversy was widespread.”

Although the APA subsequently developed new research ethics guidelines that would have made Milgram’s experiment impossible, Milgram was cleared of any wrongdoing.


But stricter ethics guidelines did not stop Zimbardo 10 years later.

The Stanford prison experiment, which tested participants’ reactions to being placed arbitrarily in the role of either prisoner or guard, aimed to show that people would fall into their designated roles as a result of institutionalized power dynamics, Zimbardo said.

Zimbardo’s hypothesis proved to be correct, but the results came in much faster than he expected. Within 36 hours the first prisoner, someone Zimbardo selected for being “normal” and healthy, had an emotional breakdown.

As with Milgram’s study, the Stanford prison experiment raised ethical concerns within the psychology field and in the media, said psychology professor Edward Zigler. But, he added, the significance of the study’s findings did partially overshadow some of its ethical issues.

Because nobody could have predicted the extremity of the study’s events, the proper authorities approved it, Zimbardo said. In retrospect, it was unethical, he said, to make people suffer as they did, but nobody had ever imagined that the role-play would get so out of hand.

“[Milgram] was in the audience in 1971 when I first presented this research,” Zimbardo said. “He was excited because not only is it interesting, but my study was more unethical than his so I would take the heat off him.”


Aside from their parallel career paths, Zimbardo and Milgram shared a common background that nurtured similar ideas about social psychology.

Indeed, the connection between the two psychologists goes back further than their Yale roots: The two were friends at New York’s James Monroe High School. They both also grew up in the Bronx, which Zimbardo said affected how each of them viewed the world.

“I was growing up in the ghetto with evil all around me, wanting to understand it,” Zimbardo said. “Finally, I said it’s not people, it’s the situation that people are forced to live in, that makes a difference.”

Milgram’s early experiences were compounded by the fact that he was Jewish only years after the Holocaust, Zimbardo said. It was Milgram’s eagerness to understand the psychology of Nazi Germany that led him to develop his study, Elms said. Milgram, who Elms said was Eastern European Jewish, had many relatives who died in the Holocaust and struggled to comprehend how ordinary citizens could commit some of the atrocities that occurred during World War II.


Zimbardo and Milgram shared a common goal: to understand how individuals are affected by the power of situations and external influences. And regardless of the ethical questions their methods raised, the results of their experiments drew public interest as real-world events highlighted their applicability.

Shortly after the prison experiment, for example, an escape attempt at San Quentin prison in California ended in the shooting of a prisoner and three weeks later, a riot was staged at Attica prison in New York.

“Suddenly, prisoners became hot,” Zimbardo said. “I became an after-the-fact expert, talking about reform and how prisons dehumanize and alienate guards from any sense of compassion.”

More recently, Zimbardo was called as an expert witness for one of the guards in the Abu Ghraib trail.

Elms said that Milgram was very worried that Americans might be susceptible to authoritarian movements, as was the case with Nazi Germany, but that he thought the wide publicity given to Milgram’s results would reduce this possibility.

“Maybe I should be more pessimistic. …” Elms said. “But I still think the Milgram results have sensitized many people, especially college students who have studied his research, to be less willing to show unquestioned obedience to authority.”


The Stanford prison experiment and the Milgram experiment undisputably hold important places in the history of Yale psychology, Zigler said. The ethical debates they inspired are unrivaled and their findings are almost commonplace in college settings.

“You can’t pick up a textbook without [the two studies] included,” he said.

In fact, some professors like Zigler said the department was at its strongest in the 1960s while Milgram and Zimbardo were involved, and added that he does not think it is as strong today as it was a few decades ago.

Milgram and Zimbardo’s ties to the University and the significance of their findings are exciting, psychology professor Marvin Chun agreed. He noted:

“Both of these studies provided deep insights into how social pressures and situational factors can cause people to behave in ways that they would otherwise not behave.”

Selen Uman contributed reporting.