There was this one experiment, I think it was done in the aftermath of the Holocaust, where they took a bunch of random people into a room where there was this person rigged up to an electrical generator. A person of authority then told them to pull a lever. The person tied to the generator started to scream, as though they were being eletrocuted. Again and again the authority told the person to pull the lever, and the vast majority did. The person connected to the generator was an actor, and no one was being hurt, but the person being tested didn't know this. Some continued to give shocks even after the actor feigned death.