Infamous experiments almost 50 years ago discovered that ordinary people--under orders from an authority figure--would deliver apparently lethal electrical shocks to complete strangers.

The disturbing findings both shed light on the limits of human behavior and the mind but also ignited an ethical controversy that has made it impossible nowadays to further explore this area directly.

Now scientists are conducting these experiments against computer-generated virtual people, where no real people appear to get hurt. The hope is to better understand why people commit horrific acts against their fellows, such as torture or genocide, while potentially overcoming the ethical concerns against the original experiments.

These new findings build off the pioneering work of psychologist Stanley Milgram at Yale University who began his controversial experiments in 1961, months after the trial of Nazi war criminal Adolf Eichmann began.

Eichmann, responsible for the mass deportations of Jews, gypsies and others purged during the Nazi reign furthered his notoriety by insisting he was only "following orders" when confronted with his crimes.

The Milgram experiment discovered that ordinary people could easily be persuaded to give what they believed to be lethal electrical shocks to randomly chosen strangers, even if it conflicted with their own consciences, if instructed to do so by a perceived authority figure. The stranger was at no time actually hurt.

"The line of research opened up by Milgram was of tremendous importance in the understanding of human behavior," said virtual reality researcher Mel Slater at University College London. However, it triggered a firestorm over the ethics of placing volunteers in deceptive and highly disturbing situations.

Slater and his colleagues have repeated the Milgram experiment with virtual people. Volunteers gave a series of memory tests to a virtual woman. They read out five words at a time, the first of which was a cue word, while one of the other four was a word linked with the cue. The virtual woman was supposed to have memorized the word associations beforehand.

When the virtual woman gave an incorrect answer, the participants were told to give a virtual 'electric shock' that buzzed to her, increasing the voltage each time she gave an incorrect answer. The experiment told volunteers 20 times to give shocks.

Of the 34 volunteers in the experiment, 11 communicated with the virtual woman who never protested only through a text interface. The other 23 saw and heard a life-sized, computer-generated woman via a virtual reality system. Over time, she responded with increasing discomfort and protests, eventually demanding the experiment stop. Near the end, her head would slump forward and she became unresponsive.

All the volunteers who communicated with the virtual woman solely through text messages gave all 20 shocks. However, when volunteers could see and hear the virtual woman, while 17 gave all 20 shocks and three gave 19 shocks, 18, 16 and 9 shocks were given by one person each.

When volunteers were asked whether they had considered aborting the experiment, nearly half of those who could see and hear the virtual woman indicated they had because of their troubled feelings about what was happening. In addition, their heart rates indicated that participants reacted as though the situation was real.

"The results demonstrate that even though all experimental participants knew that the situation was unreal, they nevertheless tended to respond as if it were," Slater said.

"This opens the door to the systematic use of virtual environments for laboratory style study of situations that are otherwise impossible whether for practical or ethical reasons -- for example, violence associated with football, racial attacks, gang attacks on individuals, and so on," Slater said. "Why do some people participate in such activities even though it is against their nature? The original Milgram experiment helps to explain this, and the exploitation of virtual environments may help to further research into these difficult and pressing questions."

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