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The psychology behind why we believe in horoscopes

July 5, 2022

Ever wondered why so many people believe in horoscopes? Have you ever believed them yourself? Turns out, the better we understand our attraction to quack science, the better we can avoid falling victim to it.

An illustration of an astrological wheel with the signs of the zodiac
Are our futures written in the stars? Image: Allexxandar/IMAGO

What if I told you I could give you a very accurate description of your personality? 

You want other people to know you and like you. You tend to be critical of yourself and often doubt whether you have made the right decision or done the right thing. You have a great deal of potential which you have not always used to your advantage. While you have some flaws, you are constantly trying to improve. Sometimes you can be very sociable and extroverted, while at other times you are introverted and prefer to be alone. You prefer some change and variety and don't like to feel limited, but you also seek security in life. You consider yourself an independent thinker and do not accept others' statements without satisfactory proof. You have found it unwise to be too honest in revealing yourself to others.


Witch fortune-teller with crystal ball
Fortune-tellers rely on our cognitive biases such as the Barnum effectImage: Sergi Reboredo/picture alliance

You probably related to the text. Perhaps you think it described your character well. That's no surprise — in fact, it’s exactly what it was designed to do. But how?

It's because of something called the Barnum — or Forer — effect. It explains the reason why we find ourselves believing horoscopes, fortune-tellers, Tarot card readers and bogus personality tests. 

What is the Barnum effect?

The Barnum effect causes people to falsely believe that personality descriptions like the one listed above are accurate when they could actually apply to anyone. It's named after P.T. Barnum, a 19th century showman who made his name promoting hoaxes and deceptive pranks.

This psychological effect can convince us that the method or person behind such vague statements and predictions is the real deal — or even that they have supernatural powers. 

Forer's experiment

In the 1950s, a psychologist named Bertram Forer facilitated this experiment with students from his introductory to psychology course.

The text you rated earlier is very similar to the one Forer used back then, which was inspired by astrology sections in newspapers.

He gave the same text to each of his students, telling them they were the results of a personality test they had previously filled out, and therefore very personalized.

When all the students received the text with their scores, Forer asked them to raise their hands if they thought it had done a good job at describing their personality. The students were baffled when they saw that almost all hands were up. 

Forer then started to read one of the texts out loud. The students burst into laughter, realizing that all the texts were the same. 

Forer now had proof of how faulty our judgment is, and how easily we can be fooled into approving pseudo-scientific descriptions or predictions about ourselves.

What's behind the Barnum effect? 

The reason most of us can easily relate to these general descriptions is because we all have the traits they mention, just to varying degrees. 

It's not the lack or presence of those characteristics that define us, but to what extent we have them. So, saying: "You can sometimes be an introvert and sometimes an extrovert" is like saying you have a heart and two lungs. Well, of course!

For example, we can all be shy at certain times but there are people with social anxiety, for example, who experience shyness to a much higher degree than those who are able to overcome it and perform on stage.

As Forer put it in a 1949 paper describing his prior findings: "The individual is a unique configuration of characteristics each of which can be found in everyone, but in varying degrees."

Subjective validation

Another factor that plays a role in the Barnum effect is the fact that people generally tend to prefer positive and personal ideas or statements and reject negative, less personal ones. 

The brain: the central organ of the human nervous system.
Because our minds are flawed we can be irrational and subjectiveImage: magicmine/Zoonar/picture alliance

This tightly related, broader cognitive bias is called subjective or personal validation, which occurs when we perceive two coincidences to be related when they are not. David Johnson, a philosopher at King's College in London, gave an example of this phenomenon in his book Bad Arguments:

"Medium: I feel like there's a name with an S sound, maybe a father figure, possibly from this part of the crowd. 

Sitter in the audience: My husband Sam just passed. I and his two sons miss him. 

Medium: Yes, Sam is telling me that he too misses you and the boys."

Johnson said that in this case, the medium is relying on the Forer Effect to trick others into believing that something "magical" is happening.

"The medium is giving something very general — there are lots of S names, and 'father figure' could be someone’s husband, someone's father or grandfather, or even a son that is a father — that is bound to apply to someone in the crowd," Johnson wrote. 

This phenomenon is similar to confirmation bias, which occurs when we only seek out information that confirms beliefs we already have and disregard anything contrary.

How our minds play tricks on us

The Barnum Effect is just one example of a cognitive bias — a subconscious, often systematic, misinterpretation or distortion of reality. 

These biases can increase our susceptibility toward certain prejudices or stereotypes, causing us to believe misinformation, seek news and articles that confirm our opinions, misjudge information and people, or simply behave and think irrationally.

Being aware of these biases is the best way to avoid falling victim to them, researchers say. 

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Edited by: Clare Roth