From Wikipedia, the free encyclopedia: http://en.wikipedia.org/wiki/Milgram_experiment
The method of one experiment was as follows:
The subject and an actor pretending to be another subject are told by the experimenter that they were going to participate in an experiment to test the effectiveness of punishment on learning behavior. Two slips of paper marked "teacher" are handed to the subject and actor, and the actor claims that his says "learner", so the subject believed that his role has been chosen randomly. Both are then given a sample 45-volt electric shock from an apparatus attached to a chair into which the actor is strapped. The "teacher" is then given simple memory tasks to give to the "learner" and instructed to administer a shock by pressing a button each time the learner makes a mistake.
The "teacher" is then told that the voltage is to be raised by 15 volts after each mistake. He is not told that there are no actual shocks being given to the actor, who feigns discomfort. At "150 volts", the actor requests that the experiment end, and is told by the experimenter "The experiment requires that you continue. Please go on." or similar words. He continues, and the actor feigns greater discomfort, considerable pain, and concerns for his own safety as the shocks continue. If the teacher subject becomes reluctant, he is instructed that the experimenter takes all responsibility for the results of the experiment and the safety of the learner, and that the experiment requires that he continue.
Before the experiment was conducted Milgram polled fellow psychiatrists as to what the results would be. They unanimously believed that all but a few sadists would refuse to give the maximum voltage.
In Milgram's first set of experiments, 65% of experimental subjects administered the experiment's final "450-volt shock", though many were quite uncomfortable in doing so. No subject stopped before the "300 volt" level. The experiment has been repeated by other psychologists around the world with similar results. Variations have been performed to test for variables in the experimental setup. For example, subjects are much more likely to be obedient when the experimenter is physically present than when the instructions are given over telephone.
The experiment raised questions about the ethics of scientific experimentation itself because of the extreme emotional stress suffered by the subjects (even though it was brought on by their own free actions). Most modern scientists would consider the experiment unethical today, though it resulted in valuable insights into human psychology.
In Milgram's defense, given the choice between "positive", "neutral" and "negative", 84% of former subjects contacted later rated their role in the experiments as a positive experience and 15% chose neutral. Many wrote later expressing thanks.
Why so many former subjects reported they were "glad" to have been involved despite the apparent levels of stress, one subject explained to Milgram in correspondence six years after he participated in the experiment:
While I was a subject in 1964, though I believed that I was hurting someone, I was totally unaware of why I was doing so. Few people ever realize when they are acting according to their own beliefs and when they are meekly submitting to authority. ... To permit myself to be drafted with the understanding that I am submitting to authority's demand to do something very wrong would make me frightened of myself. ... I am fully prepared to go to jail if I am not granted Conscientious Objector status. Indeed, it is the only course I could take to be faithful to what I believe. My only hope is that members of my board act equally according to their conscience...
Milgram summed up in the article "The Perils of Obedience" (Milgram 1974), writing:
"The legal and philosophic aspects of obedience are of enormous import, but they say very little about how most people behave in concrete situations. I set up a simple experiment at Yale University to test how much pain an ordinary citizen would inflict on another person simply because he was ordered to by an experimental scientist. Stark authority was pitted against the subjects' strongest moral imperatives against hurting others, and, with the subjects' ears ringing with the screams of the victims, authority won more often than not. The extreme willingness of adults to go to almost any lengths on the command of an authority constitutes the chief finding of the study and the fact most urgently demanding explanation."
The experiments began in July 1961, a year after the trial of Adolf Eichmann in Jerusalem. Milgram devised the experiment to answer the question "Could it be that Eichmann, and his million accomplices in the Holocaust were just following orders? Could we call them all accomplices?" (Milgram, 1974)
Thomas Blass of the University of Maryland writes in Psychology Today (March/April 2002) that he has collected results from repeats of the experiment done at various times since, in the US and elsewhere, and found that the percentage of subjects who are prepared to inflict fatal voltages remains remarkably constant, between 61% and 66%, regardless of time or location. The full results were published in the Journal of Applied Social Psychology (see reference below).
A documentary was made showing the experiment and its results. It is now very hard to find copies of it, but it is a very informative and chilling viewing.