Ordinary people delivered shocks they thought were lethal because a man in a coat said to

In 1961, Stanley Milgram told volunteers to give an unseen 'learner' increasingly severe electric shocks every time he answered wrong. Despite cries of pain from the next room, 65% of participants obeyed all the way to the maximum, seemingly lethal voltage simply because an authority figure calmly told them to continue.

— Stanley Milgram, Behavioral Study of Obedience — Journal of Abnormal and Social Psychology, 1963