Replicating the Milgram experiment

One of the most famous (and infamous) studies in psychology is Stanley Milgram’s series of experiments on obedience to authority. (If you haven’t come across this work before, Wikipedia has a summary, or you can visit the Milgram website, or read Milgram’s original paper (pdf file).) The Milgram effect – that ordinary people are, under some circumstances, prepared to inflict extreme suffering and even death on a fellow human being – has been used to explain many real world examples (including genocide, state torture and terrorism). Many of the original Milgram participants suffered psychological distress and the experiments are therefore considered by most psychologists to be unethical. They have never been replicated by scientists*. Until now.

A team at University College London has carried out what they believe to be an ethical replication of the Milgram experiment in virtual reality. The UCL press release (20 Dec) explains:

By repeating the Stanley Milgram’s classic experiment from the 1960s on obedience to authority – that found people would administer apparently lethal electrical shocks to a stranger at the behest of an authority figure – in a virtual environment, the UCL (University College London) led study demonstrated for the first time that participants reacted as though the situation was real.

[…] Following the style of the original experiments, the participants were invited to administer a series of word association memory tests to the (female) virtual human representing the stranger. When she gave an incorrect answer the participants were instructed to administer an ‘electric shock’ to her, increasing the voltage each time she gave an incorrect answer. She responded with increasing discomfort and protests, eventually demanding termination of the experiment. Of the 34 participants 23 saw and heard the virtual human and 11 communicated with her only through a text interface.

[…] The results show there was a clear behavioural difference between the two groups depending on whether they could see the virtual human. All participants in the Hidden Condition (HC) administered all 20 shocks. However, in the Visible Condition (VC) 17 gave all 20 shocks, 3 gave 19 shocks, and 18, 16 and 9 shocks were given by one person each.

Participants were asked whether they had considered aborting the experiment. Almost half of those who could see the virtual human indicated they had because of their negative feelings about what was happening. Measurements of physiological indicators including heart rate and heart rate variability also indicated that participants reacted as though the situation was real.

Given that participants reacted as if the situation was real, and that they had negative feelings about what was happening, I am not sure that this actually counts as an ‘ethical’ replication of the Milgram study. (I’m not the only one – William Dutton of the Oxford Internet Institute has apparently commented along similar lines, but the full report is behind a news@nature paywall.)

The virtual reality study is freely available in PLOS ONE (a public access journal).

*I said that the experiment had not previously been replicated by scientists, but ethical constraints don’t seem to stop the entertainment industry. A couple of years ago magician Derren Brown put reality show volunteers through the same experiment (pdf), and the Huffington Post reports that US TV channel ABC will screen a replication of the study on 3 January 2007.

UPDATE (11 Jan): Collision Detection has an interesting post on the UCL study.