Stanley Milgram. Next month marks the 50th anniversary of Milgram's first published paper on the experiment. The event has inspired conferences - including one at Yale next month - and a special issue of the Journal of Social Issues, and it is occasioning fresh examination of Milgram's work. Scholars working in the Milgram archives at Yale University have, in recent years, begun to suggest that the experiments told a more complicated story than most people understand. Of the many versions he ran, not all of them yielded such damning results, and their methods may not be as consistent as he reported. A new entry on the critical side is a book, Behind the Shock Machine: The Untold Story of the Notorious Milgram Psychology Experiments, just published in the US by Australian journalist and psychologist Gina Perry. Perry says she set out with a respectful view of Milgram, thinking she would be simply fleshing out the story of the experiments by tracking down as many test subjects as she could and telling their side of the story, with the help of the archives. But, she says, she came to be appalled by the way the subjects were treated, and surprised by what she calls the sloppiness of his research. ''The closer I looked at the inner workings of the experiment, the more contrived and unconvincing the results seemed,'' she writes. While there are psychologists who agree with that stance, others worry it will induce people to dismiss a still important set of findings because the experiments don't meet the standards of 21st-century research. But for Perry and others, the flaws and irregularities in the experiment are far more than minor details. How you parse those details may determine whether you believe we should put faith in Milgram's work at all. Milgram's experiments made their first appearance in print in October 1963, in the Journal of Abnormal and Social Psychology. That article focused on an experiment in which the person supposedly being shocked took the shocks silently at first, then pounded on the door if the voltage reached 300 volts, and again at 315, and then went silent. Sixty-five per cent of subjects nevertheless kept turning the electricity up to the highest voltage. Milgram, aware of the public impact his work might have, filmed several subjects in the last days of the experiments. He used that footage to make a documentary film, Obedience.

''Can't you check in to see if he's all right?'' a clearly distressed subject, Fred Prozi, a central figure in Obedience, asks plaintively, after a once-hollering ''learner'' goes silent. ''Not once we've started,'' says the experimenter. ''Please continue, teacher.'' Prozi continues, but also gets out of his seat, pushes his papers away, and puts his head in his hands. The fascination followed swiftly, as did the backlash. In June 1964, in American Psychologist, psychologist Diana Baumrind blasted the ethics of the experiment, singling out Milgram's ''posture of indifference'' towards his subjects, and asking whether the set-up could provide any insight into how people would act in the real world. She also questioned whether Milgram's short, casual debriefing of his subjects afterwards, in which he told them no deadly shocks were involved, was sufficient to counteract the ordeal he had put them through. Those criticisms have dogged the experiments to this day. Despite Milgram's relative fame, his work didn't do wonders for his academic career. He failed to get tenure at Harvard, where he moved in 1962, and was denied follow-up funding for his work. He taught at the City University of New York until his death in 1984. Partly because of the furore, universities created guidelines that would prevent the study from being replicated in its original form. Milgram has always had his defenders as a visionary. His work has experienced a revival of interest in recent years, spurred by such incidents as the use of torture in the war on terror and the mistreatment of captives at Abu Ghraib. Such books as The Obedience Experiments: A Case Study of Controversy in Social Science, by Arthur G. Miller, a professor of psychology at Miami University, and a biography, The Man Who Shocked the World: The Life and Legacy of Stanley Milgram, by Thomas Blass, a psychologist at the University of Maryland, start from the premise that he raised profound questions about human behaviour under duress.

As Perry's book points out, the findings were never so cut and dried. The first published study and scenes from Obedience stick in the mind, but in fact Milgram carried out two dozen related experiments, involving various degrees of coercion. In one, the ''teacher'' had to push the ''learner's'' hand down on an electrical plate; in another, the experimenter gave instructions about the shock procedure and then left the room; in a third, there were two ''experimenters'' who gave conflicting advice. (When both experimenters were in the room, not one of the subjects turned the voltage to the highest level.) In more than half the experiments, at least 60 per cent of the subjects disobeyed the experimenter before reaching the maximum - a statistic that might change your impression about how compliant the subjects were. There is also a question about whether the subjects thought they were hurting anyone: Milgram said three-quarters believed in the set-up, but that includes the 24 per cent who said they had ''some doubts''. Some of these complications were described by Milgram in the book, Obedience to Authority: An Experimental View, published in 1974; others have been unearthed by scholars in the archives. Perry, in her book, raises a deeper issue that has been touched on by a few other scholars who have spent time in the Milgram archives - his practices in the lab could diverge quite a bit from what he reported in his articles. In an article published in History of Psychology this year, for instance, Stephen Gibson, a senior lecturer in psychology at York St John University, noted that sometimes the experimenter would comply with the subjects' demand that he go behind the screen to check on the suddenly silent ''learner''; when that happened, the experimenter would return to say he was fine. That detail was omitted in Milgram's write-ups. The tapes also suggest Milgram's experimenters sometimes departed from the script, making the findings less reliable overall. Milgram described a clear set of four ''prods'' he was to use: ''Please continue'' (or ''Please, go on''); ''The experiment requires that you continue''; ''It is absolutely essential that you continue''; and, ''You have no other choice, you must go on''. In the write-ups, Milgram gave the impression that once the experimenter had run through these prods, if the subject still baulked, the experiment ended. But listening to archived tapes, Perry heard the experimenter downright ''badgering people'', repeating the prods and introducing new ones. ''You hear a moving of the goal posts,'' she says. In one set of experiments involving female subjects, she says, the experimenter insisted 26 times that one woman continue, turned the shock machine back on after another subject turned it off in protest, and got into an argument with a third. ''When you hear the extent to which [the experimenter] coerced the women to stay in that lab, it's quite distressing,'' Perry says.

The distress of the subjects became Perry's biggest concern as she researched her book, and it was heightened by her discovery that the limited debriefing - where the set-up was revealed - was even more partial than previously thought. Milgram would often say that 84 per cent of his subjects reported having been glad to be part of the experiment (1.3 per cent were ''sorry'' or ''very sorry'', with the rest indifferent), and that everyone was ''dehoaxed''. But 600 people out of 780, Perry says, were told at first only that the shocks weren't as bad as described, not that they were entirely fake. Milgram later mailed out a full explanation of the experiment, but that was nearly a year later, and some people never got it, or apparently failed to read it. One subject Perry tracked down, Bob Lee, only learnt what he had been through in 1993, when he read an article about the experiments. He told Perry that whoever ran the experiment was ''a son of a bitch'' and still seemed puzzled: ''What was it about, anyway?'' Some subjects, like Bill Menold, a one-time credit union employee in New Haven, took home the lesson Milgram intended: ''There's a little evil in there, you know,'' he said, pointing at himself. Yet another couldn't remember at what voltage he stopped, and worried at the issue obsessively, Perry reports. The shorthand descriptions of the experiments that appeared in textbooks fail to capture how torn even most of the ''obedient'' subjects were, Perry says. Listening to the tapes, she heard people who were ''alert, agonised, intelligent'' - yet, she says, ''They are spoken of in the same breath as Nazi concentration-camp guards.'' Today, some psychologists think Milgram's experiments were of inestimable value, while others believe they produced little more than gratuitous torment. Perry says, dismissively, they ''demonstrated something in a lab in 1961 and 1962 about what scientists can get people to do''. Blass has read many of the same archival papers as Perry. He admires the verve of her book, but ''when there's speculation that could go one way or another, [Perry invariably] goes in the way that's damaging to Milgram''. Should Milgram be criticised for his incomplete debriefings, he asks, or praised for debriefing people at all in an era when many researchers did not?

A clear problem is that evolving ethical standards make Milgram's findings basically impossible to replicate. But in 2009, Jerry Burger, a professor at Santa Clara University, gave it a shot. He published the results of a Milgram-like study carefully tailored to get past university ethics boards. Test subjects were screened for anxiety, the experiment ended if the subject pressed the 150-volt lever after a single protest from the ''learner'', and everyone was thoroughly debriefed afterwards. In that experiment, 70 per cent pulled the lever to the maximum. ''To say that people disagree about how to interpret Milgram's studies is absolutely correct,'' says Burger. ''Is he really studying obedience? Is it really related to the Holocaust? There are volumes written about this over the last 50 years. That's different from saying the findings are unreliable.'' One universally acknowledged weakness of Milgram's work is that he failed to provide a robust theory for why people acted the way they did. He simply asserted they ceded their agency to the authority figure, a claim that doesn't seem to match the complexity of the interactions in the lab. Stephen Reicher, a psychologist at the University of St Andrews, argues that people weren't passive, as Milgram stated, but rather sought a way, in a highly ambiguous situation, to frame their behaviour as a positive good: they were moving science forward. ''It's not a black-and-white situation,'' says Perry. ''People were looking for some resolution of the ambiguity; they looked to the experimenter as the representative of an Ivy League university. A lot of people expressed faith Yale wouldn't harm someone.'' Whatever the flaws in Milgram's methods, it's clear he raised tantalising and unresolved questions about how humans respond to pressure to do harm. The issue now is how, with different, tougher ethical standards, we can move beyond these studies while probing similarly vexing issues - especially given the shadows Milgram's work still casts. Burger has offered his 21st-century shock machine to anyone with a promising research project, he says. So far, he's had no takers.

BOSTON GLOBE