What is the Barnum Effect?
The Barnum effect, also known as the Forer effect, refers to vague and usually positive personality descriptions which are completely generic but which most people rate as highly accurate specifically for them.
It is named after the circus entertainer P. T. Barnum (about whom the movie The Greatest Showman was made). Among many other acts and exhibits, Barnum gave personality tests as a circus performance, impressing people with how accurate they apparently were.
Bertram R. Forer was a psychologist who demonstrated as a formal experiment what Barnum had demonstrated as a performance trick. Forer conducted a personality test on 48 of his students, gave them their results in the form of a short written personality description, and asked them to rate the accuracy of the description on a scale of 1 to 5. The students rated the descriptions 4.2 out of 5 on average. The catch was that Forer had ignored the test answers and given every student the same personality description.
Example sentences from Forer’s universal description include:
- You have a tendency to be critical of yourself.
- While you have some personality weaknesses, you are generally able to compensate for them.
- You pride yourself as an independent thinker and do not accept others’ statements without satisfactory proof.
- At times you are extroverted, affable, sociable, while at other times you are introverted, wary, reserved.
Forer’s experiment was inspired by a graphologist who offered to give him a personality reading based on his handwriting. The graphologist claimed that his previous clients were impressed with the accuracy of his readings. Forer was skeptical, and claimed that it would be possible to achieve equally impressive-looking results from a blind reading, without a handwriting sample.
Properties of Barnum / Forer Effect Statements
The statements are broadly applicable to most people, and generally flattering, but not in a blatant way, instead recasting negatives as positives.
Subsequent research has found that the phrase “at times” (as in the final example above) is very effective for generating Barnum effect statements. Most people exhibit a mixture of opposing traits at different times, and the phrase “at times” is noncommittal about what proportion of the time it refers to. So the final example statement above will apply to anyone unless they are extroverted absolutely all the time or introverted absolutely all of the time.
Research building on Forer’s work has also found that positive or neutral statements are perceived as more accurate than negative statements, because of self-serving bias.
Statements about people’s inner thoughts are good examples of the Barnum effect, because the statement may be near-universal but people might not realize that, as they have access to their own inner thoughts but not other people’s. Someone who is self-critical might be under the mistaken impression that this is a fairly unusual trait specific to them, if they perceive other people as being self-confident on the outside.
Example Applications of the Barnum Effect
Horoscopes exploit the Barnum effect. It is obviously difficult to divide the population into twelve groups and write specific descriptions of each group that ring true for most of the people in it. Horoscope writers get around this problem (consciously or unconsciously) by making the descriptions vague and flattering, so most people, regardless of their star sign, can read a description and believe it applies specifically to them.
This applies both to the kind of horoscope which statically describes personality (for example, “You feel things deeply and your emotions are more complex than people realize”), and the kind which predicts the coming week (for example, “Acting with integrity will pay off for you this week – do not be tempted to take short cuts”).
The Barnum effect is not the only cognitive bias involved with belief in horoscopes. Confirmation bias also plays a large part, in that people will be on the lookout for situations in the coming week that match the horoscope prediction, and will notice and remember them.
In a 1971 experiment by Bernie I. Silverman, subjects were given twelve horoscope descriptions and asked to pick the ones that best described themselves. If they were told which horoscope went with which star sign, they tended to pick the one that went with their own star sign, but if they were not told which horoscope was which, there was no link between the ones they picked and their actual star sign. This suggests that the horoscopes do not objectively match the people they’re meant to describe, but in the case where the horoscopes are labeled with star signs, the Barnum effect is at work, with people perceiving the horoscope for their own star sign as matching them – even if it’s actually such a poor match that they couldn’t pick it out if it wasn’t labeled with the star sign.
Another application of the Barnum effect is in cold reading. Psychics and mediums can demonstrate insight into subjects’ personalities that seems so accurate that it must be paranormal in origin, when in fact it consists of generic Barnum-effect statements which could be applied to most people.