Stanford Prison Experiment

One of the most famous, and debated Social Psychology experiments of all time is the the Stanford Prison Experiment. This highly debated study caught the psychology world off guard. The Stanford Prison Experiment asked the question, “What happens when you put good people in an evil place?”

Date: August 14-20, 1971

Experimenter: Phil Zimbardo, Stanford University

Goal: To better understand the effect imprisonment has on people, specifically the relationship between guards and prisoners.

Background/Reason for study: The US Navy wanted to understand what caused the conflict between guards and prisoners.

Participants: 24 men who responded to a news paper add, all received $15 (roughly $88 today), all of whom were screened for criminal records, mental health issues, and medical problems.

Method: The participants were randomly divided into two groups, prisoners and guards. There would be 12 in each group, 9 participants and 3 alternates. A mock prison was set up in the basement of psychology building at Stanford. The study was planned for 7-14 days.  The prisoners were “arrested,” finger printed and brought to the “jail.”

The guards were overseeing the prisoners and were instructed that they could not physically harm the prisoners, but could instill fear, and were permitted to exercise their authority through intimidation. The prisoners were given outfits to wear that looked like actual jailhouse suits that came from a military store. The guards wore dress like that of an actual guard and asked to wear mirrored sun glasses to avoid eye contact with the prisoners.

Stanford Prison Experiment
Dogs and humans both bully

The most important thing to remember: This is not an actual prison, no one has committed any crimes. This is just an observation of the relationship between the appointed guards and the appointed prisoners. The men all had an equal chance of either being a guard or a prisoner.

Results: Pandemonium broke out in the “jailhouse.” The experiment barely made it six days before it was shut because of the emotional reaction of some of the prisoners. Essentially, a real prison broke out. The guards were belittling and degrading the prisoners in a variety of fashions. The prisoners were rebelling against the authority the guards in many ways including a hunger strike.

The mirrored sunglasses were believed to reduce eye contact and help the dehumanization process of the prisoners. The inmates had to chant their assigned numbers, were forced to chant things in unison, and degraded in many horrific capacities. The emotional breakdown of the prisoners was extreme and Zimbardo was forced to shut the study down early. The abuse of authority was apparent.

Controversy: The study is criticized for the treatment of the participants. The guards were continuously degraded, embarrassed, and while no physical harm was present, the emotional risks were real. The study also had some issues with the role that Zimbardo played as the warden of the Stanford Prison Experiment, causing him to need to shift roles. There also is some hint that maybe a selection bias occurred.

Key Concepts: Deindividuation, depersonalization, social dominance

The study in three words: Power is Scary

Interesting Fact: Philip Zimbardo and Stanley Milgram  were classmates James Munroe High School in New York.

Zimbardo, P (1999). The Stanford Prison Experiment. Retrieved from Stanford Prison Experiment:

To reference this article

Mikita, D. (2016). The Stanford prison experiment. Retrieved from Free Psychology Help:

In text, (Mikita, 2016).

Great video about the Stanford Prison Experiment!