The 1971 prison study was scheduled for two weeks, but was stopped after six days when college-aged students playing guards became psychologically abusive.

Philip G Zimbardo, the psychologist behind the controversial Stanford Prison Experiment which was intended to examine the psychological experiences of imprisonment, has died at the age of 91. Stanford University announced that he died on October 14 at his home in San Francisco. A cause of death was not provided.

Dr Zimbardo is remembered for an ill-fated 1971 prison study in which he recruited college-aged males to spend two weeks in a mock prison in the basement of a building on the Stanford campus.

Zimbardo, the psychologist behind the controversial "Stanford Prison Experiment" that was intended to examine the psychological experiences of imprisonment, has died. He was 91. Stanford University announced Friday that Zimbardo died Oct.

The 1971 prison study was scheduled for two weeks, but was stopped after six days when college-aged students playing guards became psychologically abusive and those playing prisoners became anxious, emotionally depressed,