In the original condition of Stanley Milgram's obedience experiment, 65 percent of participants reached the maximum shock level.
The study began at Yale University in 1961. Volunteers believed they were taking part in research on learning and memory. An experimenter instructed each “teacher” to administer increasingly strong electric shocks to a “learner” whenever an answer was wrong, although the learner was actually an actor and no shocks were delivered.
Twenty-six of 40 participants continued to the maximum labeled voltage of 450 volts in the baseline experiment, which equals 65 percent. Many participants showed visible distress while continuing to obey the experimenter's commands.
The findings are famous but debated. Later variations showed that obedience changed with factors such as the authority figure's proximity, the victim's proximity, and whether other participants refused to continue. Modern ethics rules would not permit the original deception and stress without strict safeguards.