Philip Zimbardo is an American social psychologist who was interested in how group interactions can influence individual behavior and decision-making. While teaching at Stanford, Zimbardo received funding to conduct a study using 24 healthy, undergraduate students. Initially, half of the participants were told that they were mock guards while the other half were mock prisoners for two weeks. However, the increased violence and trauma ensued by the experiment was so shocking that the experiment ended after 6 days of data collection. This became known as the widely famous Zimbardo Prison Experiment, which granted insight into how behavior alters depending on the availability of power or authority.