Stanford prison experiment

Stanford prison experiment

Plaque at the location of the Stanford prison experiment
Date	August 14–21, 1971 (1971-08-14 – 1971-08-21)
Location	Single corridor in the basement of Stanford University's psychology building
Coordinates	37°25′43″N 122°10′23″W / 37.4286304°N 122.1729957°W / 37.4286304; -122.1729957
Also known as	SPE
Type	Psychology experiment
Organised by	Philip Zimbardo

The Stanford prison experiment (SPE) was a psychological experiment conducted in August 1971. It was a two-week simulation of a prison environment that examined the effects of situational variables on participants' reactions and behaviors. Stanford University psychology professor Philip Zimbardo led the research team who administered the study.^[1]

Participants were recruited from the local community with an ad in the newspapers offering $15 per day ($113 in 2023) to male students who wanted to participate in a "psychological study of prison life". Volunteers were chosen after assessments of psychological stability and then randomly assigned to being prisoners or prison guards.^[2] Critics have questioned the validity of these methods.^[3]

Those volunteers selected to be "guards" were given uniforms specifically to de-individuate them, and they were instructed to prevent prisoners from escaping. The experiment officially started when "prisoners" were arrested by real Palo Alto police. Over the following five days, psychological abuse of the prisoners by the "guards" became increasingly brutal. After psychologist Christina Maslach visited to evaluate the conditions, she was upset to see how study participants were behaving and she confronted Zimbardo. He ended the experiment on the sixth day.^[4]

SPE has been referenced and critiqued as an example of an unethical psychology experiment, and the harm inflicted on the participants in this and other experiments in the post-World War II era prompted American universities to improve their ethical requirements and institutional review for human subject experiments in order to prevent them from being similarly harmed. Other researchers have found it difficult to reproduce the study, especially given those constraints.^[5]

Critics have described the study as unscientific and fraudulent.^[6][7] In particular, Thibault Le Texier has established that the guards were directly asked to behave in certain ways in order to support Zimbardo's conclusions, which were largely written in advance of the experiment. However, Le Texier's article has been criticized by Zimbardo for focusing mostly on ad hominem attacks and ignoring available data that contradicts his counterarguments.