The Psychology of
Philip Zimbardo, a professor of social psychology at Stanford University, conducted a
remarkable experiment. Recent prison uprisings had piqued his interest in what it means
psychologically to be a prisoner or a prison guard. Why were prisoners so disposed toward
violence? Why were prison guards so brutal?
seemed obvious. Prisoners are violent because of the type of people they are: antisocial
criminals who have little regard for other people. Guards are brutal because only brutal
people are attracted to such an occupation in the first place.
suspected that the dynamics of prison life depend on more than the personalities of the
individuals involved. He wondered whether the structure of the prison situation played a
part in turning prisoners and guards into mean and violent people.
With the help
of several colleagues, Zimbardo created a mock prison in the basement of the Stanford
psychology building. There he could observe volunteer subjects in the roles of prisoners
Of the 70 or
so students who answered his ad for volunteers, Zimbardo chose two dozen mature,
emotionally stable, intelligent young men to be part of the study. None had a criminal
record. They were, as he put it, the "cream of the crop of this generation."1
were designated as "prisoners" with a flip of a coin; the rest served as
When it was
time for the experiment to begin, the prisoners were unexpectedly picked up at their homes
by a city police officer in a squad car. They were searched, handcuffed, fingerprinted,
blindfolded, and taken to the "prison."
prisoners were stripped, given a uniform and number, and placed in a cell with two other
inmates. They were told the cell would be their home for the next 2 weeks.
guards arrived, they were informed that they had the authority to make up their own rules
for maintaining law, order, and respect in the prison and were free to improvise new ones
at any time during their 8-hour shifts on duty.
experiment was supposed to last for 2 weeks, it had to be stopped after only 6 days.
Zimbardo described the situation as follows: