famous psychology experiments

Against the backdrop of two world wars and a century of exponential change around the world, the field of psychology has evolved dramatically over the last one hundred years. During this time, many intellectuals’ turned their attention towards better understanding the human mind in order to explain the horrors and excitements of the modern world.

In the last century psychologists have devised insightful, bizarre, profound, and often controversial experiments to better help them on this quest to understand why people behave in certain ways, and how these behaviours shape the world we live in. Here are 3 of the most interesting psychology experiments ever conducted, and what we were able to learn from them.

The Milgram Experiment

Set up:

In 1961, Yale Social Psychology Professor Stanley Milgram set out, like so many of his contemporaries, to understand how the atrocities committed by Nazi soldiers during the Second World War were possible. The experiments started a year after the trial of SS leader Adolf Eichmann, to answer the question - “Could it be that Eichmann and his accomplices in the Holocaust were just following orders? Could we call them all accomplices?” Milgram’s ‘Study in Obedience’ experiment sought to answer this.

The experiment:

A ‘teacher’ (the volunteer) was taken into a room with a ‘researcher’ (an actor), whilst in the next room sat the ‘learner’ (another actor), who was perceived to be wired with electrodes connected to an electric ‘shock generator’.

The teacher would test the learner by naming a word and asking the learner to recall its pair from a list of four possible choices that had been pre-memorised. The teacher was then told to administer an electric shock every time the learner made a mistake, increasing the level of shock each time. There were 30 switches on the shock generator marked from 15 volts (Slight Shock) to 375 volts (Danger: Severe Shock) to 450 volts (XXX).

The learner gave mainly wrong answers on purpose, and was instructed to dramatically express his pain as the voltages increased - audible to the teacher in the next room. If the teacher refused to administer the shock, he was given a series of orders, or “prods” to encourage them to continue. If a prod wasn’t obeyed, the next more authoritative order, such as ‘’It is absolutely essential that you continue’’ was given. Surprisingly, or perhaps not, 65% of the participants continued to the potentially highest level of 450 volts, while all the participants continued to 300 volts.


The results of Milgram’s study suggested that ordinary people are highly likely to follow orders, however extreme, when given by a figure of authority (in the case of this experiment, ‘the researcher’ in the white coat). Obedience to authority, it was suggested, is ingrained in us all from the way we are raised.

The results horrified Americans of the time, in that ordinary citizens, under the right circumstances, were able to administer potentially lethal voltages of electricity to citizens just because an authoritative voice told them to. Notably though, all the test subjects were male, to reflect the military nature of the question Milgram sought to answer with this provocative experiment.

Stanford Prison Experiment

Set up:

One of the most profound and controversial psychology experiments ever conducted was led by the eccentric and talented Dr. Philip Zimbardo at Stanford University. In 1971, he launched a proposed two-week experiment to test the psychological effects of becoming a prisoner, or a prison guard. Eighteen volunteers were assigned roles as either guards or inmates, and were put into a small ‘prison’ that had been constructed in the basement of the department building.

For authenticity, and to get the volunteers in the right mind set, the prisoners were ’arrested’ from their homes and ‘charged’ with armed robbery. The guards were given prison officer uniforms, and importantly, mirrored sunglasses, to depersonalise them by preventing eye contact.

The experiment:

After a few days Zimbardo confessed that the characters struggled to get into their roles, and feared the project would have to be abandoned due to lack of activity. But it didn’t take long for things to start escalating.

As the volunteers began to adapt to their new-found roles, the prisoners decided to rebel, refusing orders and blockading themselves in their cells. The guards saw this as a challenge to their assigned authority – and the punishments began, as the methods evolved to extremity. Press-ups and other exercises designed to humiliate the prisoners were ordered, fire extinguishers were used to get them out of their cells, and prisoners were stripped naked with bags placed over their heads – to name but a few of the extreme methods that the guards adopted.

A closet in the makeshift jail was also turned in to an ‘isolation’ room, where disobedient prisoners could be locked. Unsurprisingly, some of the prisoners started to show signs of the psychological toll the experiment was taking. After only 6 days, and thanks to the intervention of a Ph. D student who came to observe, the planned two-week experiment was discontinued on ethical grounds.


Critics have often pointed out that it was a heavily manipulated environment – from the mirrored sunglasses and instructions to keep order given to the guards, to the small cells and heavily bolted chains on the ankles of the prisoners. However, this was one of the very theories that was being explored – the systematic problems with placing people in certain environments, and how this can elicit some of the worst human behaviours. The results of the experiment made Zimbardo the go-to man for government committees discussing prison reform in the US in the following decades.

Following the atrocities committed by American soldiers at the Abu Ghraib prison in Iraq, Zimbardo’s experiment was once again thrown into the limelight – held as an example of how easily ordinary people can abuse their power when placed in extreme, dehumanising conditions.

The Third Wave

Set up:

An idea born of a simple question that occupied the public imagination of post-war Western Europe - ‘’How could the German population plead ignorance about the atrocities of the Nazi party?’’ This is the question charismatic California high school teacher Ron Jones was asked of his inquisitive class in 1967. What better way to demonstrate the intoxicating allure of fascist regimes than demonstrate that it could work over in the US? To begin with, the eccentric teacher articulated the beauty of discipline, and the effects it has on people and the way they feel. And then the experiment began…

The experiment:

To start a successful fascist regime, you begin by implementing strict rules. Jones set out the basics - the class must march in an orderly fashion when they entered the classroom in silence. They must all sit in an upright position with their hands clasped in front of them. When the students saw each other anywhere in the school, they had to salute each other using a clasped hand signal he had devised. The movement developed. Membership cards were issued to active participants of the Third Wave. Members were encouraged to recruit other students in the school, and actively report any members not saluting each other and following the rules, even outside of the classroom.

By the third day, Jones was surprised no one had stepped in and stopped the experiment. He decided to hold a secret ‘rally’ in the main school hall for members (two hundred by this point) at the end of the first week. As the students gathered in the hall expecting some kind of rousing speech from their ‘leader’, Jones sat them down and hit the play button, screening a documentary about the Nazi regime and the perils of totalitarianism. Needless to say the students’ fervour for the community they had created came to a grinding halt. A very practical lesson was learned.


As Mr. Jones and his students discovered during the experiment, with some simple organisational and disciplinary tools, it was fairly easy to build a community who accepted his authoritarianism. What surprised Jones and also other teachers was the effect the Third Wave had for a short time on the focus, enthusiasm, and participation demonstrated by the students – which they found to be equally encouraging as they did disturbing.

Interested in learning more about psychology, and gaining a better understanding of the human mind? Take a look at Arden University’s Psychology & Social Sciences bachelor’s and master’s programmes.

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