Jerry M Burger, in American Psychologist, replicated part of Milgram experiement, stopping at 150 volts, the point where subjects cry out to stop. (Ethics committees bar experimenters going to the 450 imaginary line) More than half agreed to go to 150 volts. Burger interviewed participants afterward: "those who stopped generally be3leived themselves to be responsible for the shocks, whereas those who kept going tended to hold the experimenter accountable." Burger also notes that uncertainty in an unfamiliar setting and perceived time pressure to make quick decisions also made subjects "more compliant than they would otherwise have been."
Benedict Carey, "Decades Later, Still Asking: Would I Pull that Switch?, NYT, July 1, 2008, D1, D6.