Chapter thirteen begins to go over the field of social psychology and what it entails. One key aspect of this chapter is the art of obedience and the psychology behind following orders. Stanley Milgram played a key role in the understanding of the principles underlying irrational group behavior. One of his most famous and controversial experiments emphasized the obedience of authority and shed some light on how a man like Adolf Hitler could convince so many people to commit unspeakable crimes. In the experiment, a "learner" would walk into a room and strap his arm to a shock plate. Then, a person that the experiment was testing would read a question. If the "learner" answered the question correctly, the reader would do nothing. If the "learner" answered incorrectly, the reader was to shock the "learner" using a shock generator, increasing the voltage for each wrong answer. Although the "reader" could not see the "learner" being shocked, sounds of agony could be heard through the wall. Due to the "doctors" reassurance, every single person being tested went up to at least 150 volts, and three out of every five people showed complete compliance by going all the way up to 450 volts.