Stanley Milgram's "Obedience to Authority" experiments are infamous classics of psychology and social behavior. Back in the 1960s, Milgram set up a series of tests that showed seemingly normal people would be totally willing to torture another human being if prodded into it by an authority figure.
The basic set-up is probably familiar to you. Milgram told his test subjects that they were part of a study on learning. They were tasked with asking questions to another person, who was rigged up to an electric shock generator. When the other person got the questions wrong, the subject was supposed to zap them and then turn up the voltage. The catch was that the person getting "zapped" was actually an actor. So was the authority figure, whose job it was to tell the test subject that they must continue the experiment, no matter how much the other person pleaded for them to stop. In Milgram's original study, 65% of the subjects continued to the end of the session, eventually "administering" 450-volt shocks.
But they weren't doing it calmly. If you read Milgram's paper, you find that these people were trembling, and digging nails into their own flesh. Some of them even had seizure-like fits. Which is interesting to know when you sit down to read about Michael Shermer's recent attempt to replicate the Milgram experiments for a Dateline segment. Told they were trying out for a new reality show, the six subjects were set up to "shock" an actor, just like in Milgram's experiments. One walked out before the test even started. The others participated, but had some interesting rationales for why they did it — and a simple ingrained sense of obedience wasn't always what was going on.
Our third subject, Lateefah, became visibly upset at 120 volts and squirmed uncomfortably to 180 volts. When Tyler screamed, "Ah! Ah! Get me out of here! I refuse to go on! Let me out!" Lateefah made this moral plea to Jeremy: "I know I'm not the one feeling the pain, but I hear him screaming and asking to get out, and it's almost like my instinct and gut is like, 'Stop,' because you're hurting somebody and you don't even know why you're hurting them outside of the fact that it's for a TV show." Jeremy icily commanded her to "please continue." As she moved into the 300-volt range, Lateefah was noticeably shaken, so Hansen stepped in to stop the experiment, asking, "What was it about Jeremy that convinced you that you should keep going here?" Lateefah gave us this glance into the psychology of obedience: "I didn't know what was going to happen to me if I stopped. He just—he had no emotion. I was afraid of him."