The Stanford Prison Experiment (SPE) was a psychology experiment to see the effects of becoming a prisoner or a prison guard on human behaviour and psychology. The experiment ran from 15-21 August 1971, led by Dr Philip Zimbardo at Stanford University. In the experiment, 24 student volunteers were assigned to be either a ‘guard’ or a ‘prisoner’ in a fake prison at the flip of a coin, and Zimbardo was the . They were paid 15$ a day. The experiment was intended to run for 2 weeks, but some of the guards quickly became authoritarian and began psychologically torturing the prisoners, and the experiment had to be stopped after only 6 days. 5 prisoners left the experiment early, after having severe psychological stress. Zimbardo concluded that certain situations can cause good people to behave in a way that they normally would not have predicted. 