If you’d be so kind, we’d like to give you a quick personality assessment. We think you’re a generally cheerful, well-balanced person with some alternation of happy and unhappy moods. You’re neither overly conventional nor overly individualistic, and you have a wide array of interests. While you have some personal weaknesses, you’re generally able to compensate for them. How did we do? If that sounds like a perfect description of your personality, congratulations: you just fell prey to the Barnum effect.
The Barnum effect is named for the one and only P.T. Barnum, the showman famous for declaring that “there’s a sucker born every minute.” The term refers to the way you (and we!) are willing to believe that an overly broad personality description is meant just for you.
It’s sometimes called the Forer effect, after the professor who first tested the phenomenon on college students in 1949. He administered a personality test to all of his students, then told them that he would analyze their answers and give them a “brief personality vignette” one week later. Unknown to the students, everyone got the exact same personality description, full of unspecific statements such as “You have a great need for other people to like and admire you” and “You have a tendency to be critical of yourself,” most of which Forer got out of an astrology book he bought at a newsstand. Still, when asked to rate its accuracy on a scale of 1 to 5, most students gave it a 4 or higher. “The data show clearly that the group had been gulled,” Forer wrote (perhaps somewhat gleefully).
The Barnum effect has even more impact the more detailed the questions are, and the more authority you perceive the test administrator to have. It also works better if the personality description uses favorable traits. According to Psychology Today, “People tend to accept claims about themselves in proportion to their desire that the claims be true rather than in proportion to the empirical accuracy of the claims as measured by some non-subjective standard.” In other words, you’ll believe what you want to believe. And we all want to believe we “have a great deal of unused capacity which you have not turned to your advantage.”
There are many places the Barnum effect pops up that are obvious: astrology, tarot readings…it’s even at play in fortune cookies. Psychics who purport to tell your future or talk to your dead loved ones also use a form of the effect known as cold reading. But there are other places that might not be so obvious. As HowStuffWorks points out, “marketing and advertising is also quite dependent on people believing that they are the ‘kind of people’ who would benefit from a product, or have a ‘specific problem’ for which they could purchase a solution.” Even supposedly scientific personality tests work on this principle when you get right down to it.
So how do you avoid falling prey to this phenomenon? A good rule of thumb is to think about your worst enemy. Does the same trait that’s supposed to describe you also describe them? Do they also experience “some alternation of happy and unhappy moods” and “have a great need for other people to like and admire” them? If it does, it’s probably too general to be useful to you—and whoever is delivering the description probably thinks they have a sucker on their hands.