Milgram, S. (1963). Behavioral study of obedience. Journal of Abnormal & Social Psychology, 67(4), 371-378.

Following a time when Americans were trying to understand the atrocities of Nazi behavior during WWII, many questioned whether it was human nature to follow such harmful orders so obediently, or whether the Germans were simply evil.  Milgram’s classic experiment on obedience shows that while many estimated that only an average of 1% of Americans would follow directions to harm another human being, results were strikingly to the contrary.  100% of White, male, mixed background and income American participants obediently administered what they thought were painful and debilitating shocks to another person, with over 60% of participants continuing to administer shocks to the very end (levers marked XXX, 2 voltage levels above “Danger: severe shock”).  Although participants were told they could leave at any time and still receive the $20 payment, and often appeared clearly upset or tense, they continued to follow simple, non-threatening orders such as “please go on.”

This is an influential and classic study in social psychology as it was the first to highlight the power of authority on obedience and stressed the inconsequentiality of individual differences over situational factors.  Additionally, this study is classically cited as a violation of the ethical treatment of human participants (as many participants experienced severe physical reactions to the experiment) and unintentionally paved the way for institutional review boards for psychology experimentation.