The Milgram Experiment remains one of the most interesting (and controversial) psychological experiments of the 20th Century. Conducted by Stanley Milgram in 1961, the experiment was designed to test whether or not ordinary people were willing to administer a series of increasingly severe electric shocks on the orders of a figure of authority to a test subject who, in reality, was an actor pretending to be electrocuted. Astonishingly, 65% of all participants were willing to do so. Some great footage here.

Update: the old object to the video I linked to was removed from You Tube, so I’ve added in the new one.