"As prisoners arrived, they were stripped, searched and deloused, a process overseen by Dr. Zimbardo, who played the role of prison superintendent."

"Initially there were a few giggles among the participants, but as the guards began enforcing rules, the mock prison began to feel very real. Though critics have accused Dr. Zimbardo of coaching the guards to act sadistic, he told the guards only to 'create feelings of boredom, frustration, fear and a "sense of powerlessness,"' according to a defense of the study on his website. They were, he said, given no 'formal or detailed instructions about how to be an effective guard.' Within a day, the guards had become abusive and were engaging in psychological torture: making the prisoners defecate in buckets, waking them up repeatedly through the night, forcing them to simulate sodomy. Several prisoners suffered emotional breakdowns. But Dr. Zimbardo kept the study going...."

From "Philip Zimbardo, 91, Whose Stanford Prison Experiment Studied Evil, Dies/ His provocative research made him a popular figure on campus. But his exploration of how good people can turn evil raised ethical questions" (NYT).