The stanford prison experiment was a controversial study carried out by Philip Zimbardo in 1971 at Stanford University. The experiment emulated a prison scenario where participants were designated either the roles of prisoner or prison guard. The ‘prisoners’ were first picked up by mock police officers, and transported to the makeshift prison. They were referred to by numbers rather than by name, in order to dehumanise them. The guards were instructed to keep order in the prison, but were not to use any form of violence. The experiment was meant to last for a period of two weeks, but was aborted after six days, due to the guards becoming more and more aggressive towards the prisoners, and the prisoners becoming rebellious and showing extreme stress-reactions. The experiment demonstrated how quickly and easily normal people can become abusive and aggressive when in positions of power.