Experiments in evil: the shocking efforts to understand the atrocities of the Holocaust

After the Second World War, researchers developed bold, shocking new experiments in a bid to understand how the horrors of the Holocaust could have happened. David Edmonds explores their story

A 'teacher' in Milgram's study is instructed to administer an electric shock to a 'learner'.

If you were instructed to inflict pain on another person in the cause of an academic experiment, how far would you go? If that person was in agony, pleading with you to stop, would you persist nonetheless? That’s the question that Yale psychologist Stanley Milgram wanted to test.


The year is 1961. Milgram has lured subjects to his laboratory with the promise of $4 for an hour’s work. An advertisement claims that participants will assist in a study on memory. When a volunteer turns up, they’re joined by a second ‘volunteer’ and the two people draw lots to choose who’s to be the ‘learner’ and who the ‘teacher’. Unbeknown to the genuine volunteer, it’s all a setup. The genuine volunteer is given the role of teacher. The learner is an actor.

A call for participants in one of Stanley Milgram's pioneering 1960s studies - not, in fact, of memory but of the extreme actions that might result from obedience to authority
A call for participants in one of Stanley Milgram’s pioneering 1960s studies – not, in fact, of memory but of the extreme actions that might result from obedience to authority.  Image by (Granger Historical Picture Archive/Alamy)

A man in a white lab coat explains how the experiment will proceed. The teacher will sit in one room, the learner (the actor) in a separate booth. The learner is strapped into a chair and hooked up to an electricity generator. In front of the teacher is a set of small switches. The teacher is told that his job (in this experiment it’s always a ‘he’) is to read out pairs of words that the learner has to remember and then repeat. If the learner gets it wrong, the teacher must administer an electric shock. After the first mistake, he is to flick the first switch, delivering 15 volts; after the second mistake, he pulls the second – 30 volts, and so on. The final switch, 450 volts, is marked ‘danger – severe shock’.

When Milgram declared his results, they delivered another form of shock. Despite the screams from the booth, and despite expressing reservations about the suffering they were inflicting on ‘learners’, nearly two thirds of ‘teachers’ had been prepared to go all the way – eventually tripping the switch marked 450 volts.

The experiment made Milgram famous – or at least as famous as is possible for an academic working within what was then an obscure and relatively new branch of psychology, a branch that had emerged from hatred and war.

Understanding evil

Stanley Milgram was born on 15 August 1933, just months after Adolf Hitler came to power in Germany. Both of Milgram’s parents were Jewish immigrants to the US, and close relatives remained in eastern Europe. During the Second World War, the family would gather round the radio listening fretfully to the news, wondering what had become of Stanley’s aunts.

The full extent of the atrocities perpetrated against Jewish people and other minorities became apparent only at the war’s end. Six million Jews systematically exterminated: how was this possible? How could people have starved, tortured and murdered other men, women and children on an industrial scale? How could entire groups have been so dehumanised? How could millions of bystanders have allowed it to happen?

In 1961, several thousand miles from Milgram’s lab in Yale University in Connecticut, a reminder of the Holocaust appeared daily in Jerusalem: a bald, bespectacled, innocuous-looking man in a suit sitting in a glass booth. That man was Adolf Eichmann, the Nazi SS officer who had been charged with organising the mass deportation of Jews to their deaths in concentration and extermination camps.

Former SS officer Adolf Eichmann, who played a major part in the organisation of the Holocaust, in court in Jerusalem
Former SS officer Adolf Eichmann, who played a major part in the organisation of the Holocaust, in court in Jerusalem. Charged with war crimes in 1961, he claimed he had merely been “following orders”. (Image by Universal History Archive/Getty Images)

Eichmann’s trial captivated Israel. Fifteen years after the end of the Second World War, the Holocaust remained a taboo subject. Few survivors had wanted to talk about their experiences; in a perverse way, victimhood was considered almost shaming. The Jewish German-born political philosopher Hannah Arendt, in Jerusalem to cover the trial for The New Yorker, delivered her hugely contentious verdict on the accused: Eichmann was an apparatchik – a mere functionary, a cog in a bureaucratic system – and his evil was “banal”. Eichmann himself insisted he had merely been “following orders”. It was not enough to save him from a guilty verdict and the hangman’s rope.

But what of his defence? Is it possible that people do bad things just because they’re told to? Was there something unique in German culture that promoted or legitimised such blind obedience? Initially, Milgram suspected so. It could never happen in the United States, he thought. But his experiments convinced him of his naivety.

Obedience and betrayal

Milgram’s obedience experiments cemented the credentials of social psychology, the discipline that investigates how our thoughts, feelings and behaviour are influenced by others.

The man often credited as its founding father was the German-born psychologist Kurt Lewin. He had been visiting the US to deliver a series of lectures when Hitler became Chancellor. Immediately grasping that his academic career at home was over, he chose to move to the US, and eventually found a position at the University of Iowa.

It was there that he conducted the experiment for which he is best known. Struck by the difference between the political atmosphere in Germany and that in his adopted country, he devised a way to study how this affected behaviour. Boys were invited to join craft-making clubs. Some of these clubs were spearheaded by ‘democratic’ leaders who were decent to the children and welcomed their input into decision-making. Others were run in ‘totalitarian’ fashion: leaders barked curt orders, and never explained their decisions or justified their praise or blame.

The experiment produced intriguing results. For example, when the group leader left the room, anarchy was more likely to break out in the totalitarian group than the democratic one. But in many ways what was more significant was the focus of Lewin’s research – the influence on the individual of others – combined with the experimental method.

German citizens are forced to view victims of Wöbbelin concentration camp in 1945
German citizens are forced to view victims of Wöbbelin concentration camp in 1945. Several early social psychology experiments were attempts to understand the complicity of many Germans in the horrors of the Holocaust. (Image by Historical/Getty Images)

Where Lewin led, many others followed – though, post-Lewin, their experiments have tended to be conducted not in a real-life setting but in the laboratory. There were numerous psychologists I could have spotlighted in my recent BBC documentary but, besides Lewin and Milgram, I chose to emphasise three: Solomon Asch, Serge Moscovici and Henri Tajfel.

As was the case with many other social psychologists of the era, one thing the five men had in common was the Holocaust. Milgram was the only one of the five not to be uprooted from the land of his birth. A young Asch moved with his family from Poland to the United States. Tajfel, also Polish-born but later a student in France, volunteered to fight for the French when war broke out but was captured by the Germans; how he survived detention remains a mystery, though it probably entailed keeping his Jewishness secret. Born in Romania, Moscovici survived internment in a forced-labour camp during the war before moving to France. He witnessed the Bucharest pogrom of 1941, during which mobs stormed Jewish homes, raping, murdering, and inflicting torture too barbaric to describe. The memories played on Moscovici’s nerves for the rest of his life. All five men lost relatives in the war. Virtually Tajfel’s entire family was murdered, including his mother, father and brother. In later life he found it almost impossibly painful to speak in his mother tongue.

The immigrants naturally retained an outsider’s sensibility. All combined a strong Jewish identity with a weak attachment to religious doctrine, though in some cases that changed with age. In 1977, Milgram humorously declined a university meeting that had been fixed for Rosh Hashanah (Jewish New Year), replying with the quip: “Sorry for the inconvenience, but this particular holiday was scheduled 5,738 years ago, and therefore has my prior commitment.”

A discipline of deception

In trying to comprehend the Holocaust, social psychologists sought a variety of explanations. Milgram, as we’ve seen, was interested in obedience and the extent to which people’s consciences provide any check on our deference to authority. By contrast, what fascinated Solomon Asch was how we are swayed by opinion: will we go along with something if everyone else does? He tested this in his conformity experiments, which went like this.

Imagine that you are the subject. You arrive in the lab to participate in what you’ve been told is an experiment about perception. You are given a seat in a room in which six other volunteers are already seated. The test is apparently straightforward. Two cards are held up. On the first card is one line; on the second card are three lines. You merely have to say which of the lines on the second card, labelled 1 2 and 3, is the same length as the line on the first one.

All seven of you give the same answer. The experiment is then repeated with different lines. Again, the response is unanimous. But then something weird happens. On the third go, everyone else gives an answer which seems obviously wrong: they say 2, when it appears to you that the answer must be 3. Are your eyes deceiving you? How do you respond?

Asch observed that those who took part in the experiment found the experience – seeing others contradict clear evidence right before their eyes – an unnerving one. A remarkable number of people were influenced by what everyone else said. As you have by now very likely guessed, the other six participants in Asch’s study were actors, in experimental terms called ‘confederates’, pretending to be genuine volunteers.

Deception was at the heart of many other social psychology experiments. Moscovici used a deceptive setup to investigate whether minorities could influence the majority. His subjects were asked to distinguish between green and blue slides; Moscovici recorded how they were affected by a couple of confederates giving the wrong answer.

Tajfel first asked a group of boys to rate a set of paintings; they were then separated into a (Paul) Klee group and a (Wassily) Kandinsky group, and were told that this division was based on their assessment of the paintings. In fact, they were split up at random. They were then given money to share out among boys from both groups. Tajfel’s ingenious experiment revealed how easily humans divide into groups and then discriminate against other groups.

Social psychology's pioneers thought a little deception was a price worth paying, given what was at stake

No doubt the pioneers of social psychology thought that a little deception and some discomfort among their subjects was a price worth paying, given what was at stake. Perhaps they are right, though not everyone agrees. Some of Milgram’s subjects were traumatised: one man later described how he would scan the obituaries of the newspapers to see if the person who had been electrocuted had died.

Ethical concerns are among the reasons why some of these experiments are now being reconsidered with a more critical eye. In some cases, the results are also being reinterpreted. It’s been alleged that Milgram was loose with his recording and publishing of the data. He repeated the experiment several times, adjusting it in minor ways: for example, in one variation the orders of the ‘teacher’ were relayed by phone rather than in person. Overall, taking into account all variations, the majority of people in Milgram’s experiments defied the experimenters, or at least failed to follow all instructions. Still, despite some critical reappraisal, the social psychology fashioned in the shadow of the Holocaust successfully mapped out the discipline. The classic early studies on obedience and conformity and group discrimination still define the contours of social psychology today.

Social psychology is currently beset by a ‘replication crisis’. Attempts to replicate many headline-grabbing recent studies have failed. According to one of Britain’s leading social psychologists, Steve Reicher, the problem is that these days many social psychologists take a cavalier attitude to publication because they lack passion. For them, Reicher argues, social psychology is a career; beyond that, there is little personal at stake.

Nobody could level that charge at the pioneers. They were desperate to tackle racism and discrimination. “It was not in their interest to publish something they didn’t believe,” says Reicher, “because it would get in the way of a science that could make a difference”. For the founders of social psychology, whose relatives had been murdered in the ditches and camps of Europe in the Holocaust, understanding the science of evil was literally a matter of life and death.

David Edmonds is a writer and BBC journalist. Listen to The Science of Evil, his Archive on 4 programme on social psychology


This content first appeared in issue 21 of BBC World Histories magazine