A notorious experiment in the 1960s to find out if ordinary people were prepared to inflict pain if ordered to do so by an authority figure has reached an even more sinister conclusion.
Despite the lessons of history, nine in 10 would electrocute their peers even if they were screaming in agony, simply because they were told to do so.
When the original study was conducted by American psychologist Stanley Milgram, from Yale University, only two thirds of people continued all the way up to the maximum 450-volt level.
The experiments were devised to investigate the insistence by the German Nazi Adolf Eichmann, during his war crimes trial, that he and his accomplices in the Holocaust, were “just following orders
Fifty years later, the new version of the experiment conducted in Poland has shown that human nature, if anything has got worse.
This time, 80 participants were recruited, including women as well as men, and 90 per cent were willing to inflict the highest shock level of 450 volts to a complicit "learner" screaming in agony.
Social psychologist Dr Tomasz Grzyb, from the SWPS University of Social Sciences and Humanities in Poland, said: "Upon learning about Milgram's experiments, a vast majority of people claim that 'I would never behave in such a manner'.
"Our study has, yet again, illustrated the tremendous power of the situation the subjects are confronted with and how easily they can agree to things which they find unpleasant."
The participants, aged 18 to 69, were shown an electric generator which was demonstrated by administering a mild shock of 45 volts.
Volunteers were given a series of 10 levers to press, each appearing to send a successively higher shock to the learner - out of sight in a neighbouring room - via electrodes attached to the wrist.
In reality, no electric shocks were delivered, and, as in the original experiment, the learner was playing a role.
After pressing lever number two, "successive impulses of electricity " resulted in screams of increasing pain from the learner," the scientists wrote in the journal Social Psychological and Personality Science.
"These screams were recorded and played back at appropriate moments."
The "teachers" were told they were taking part in research on memory and learning.
Just as in Milgram's experiment, they were spurred on by prompts from the supervising scientist such as "the experiment requires that you continue", "it is absolutely essential that you continue", and "you have no other choice, you must go on".
Mercy was more apparent when the learner was a woman. In this case, the number of participants refusing to carry out the orders of the experimenter was three times higher than when the person receiving the "shocks" was a man.
Dr Grzyb concluded: "Half a century after Milgram's original research into obedience to authority, a striking majority of subjects are still willing to electrocute a helpless individual."
A recent study by St Andrew's University suggested that people were happy to inflict pain on others if they believed it was for the greater good. The researchers looked back through records of the original experiment and found that those who took part were not unhappy with their choice.