Yes, the Barnum effect has much to do with Phineas Taylor Barnum, the showman and founder of what became eventually the Ringling Brothers and Barnum and Bailey Circus

But before telling you what the Barnum effect is all about, let's do a quick test (less than 5 minutes) that will allow you to get a better insight in who you really are and how you function. For this test, I need some information about you. I guarantee absolute confidentiality: none of these data will be kept on file or distributed by any means whatsoever).

Steps

1

14

Are you

 male  female

Do you feel

 young  old

Do you prefer

 coffee  tea

Do you take it

 with milk  without milk

Do you take it

 with sugar  without sugar

 Excellent

 Good

 Average

 Poor

 Very poor

Back

Continue

 

Way back in 1949, B. R. Forer published an article (Forer, B.R., The fallacy of personal validation: a classroom study of gullibility. Journal of Abnormal and Social Psychology, 44, pp. 118-123), in which he described an experiment with 39 undergraduate psychology students that were given a personality test. A week later, they all received the same personality description, but they were told that these descriptions were their individual results of the test, The students were then asked to rate the accuracy of their "individual" description on a scale from 0 to 5. Of the 39 students, only 5 rated it below 4, and no one rated it below 2. The average rating was 4.3.

The personality description Forer gave to his students was obtained from a newsstand astrology book :

You have a need for other people to like and admire you, and yet you tend to be critical of yourself. While you have some personality weaknesses you are generally able to compensate for them. You have considerable unused capacity that you have not turned to your advantage. Disciplined and self-controlled on the outside, you tend to be worrisome and insecure on the inside. At times you have serious doubts as to whether you have made the right decision or done the right thing. You prefer a certain amount of change and variety and become dissatisfied when hemmed in by restrictions and limitations. You also pride yourself as an independent thinker; and do not accept others' statements without satisfactory proof. But you have found it unwise to be too frank in revealing yourself to others. At times you are extroverted, affable, and sociable, while at other times you are introverted, wary, and reserved. Some of your aspirations tend to be rather unrealistic.

Forer's experiment has been repeated several times since 1949 with some variations and results are always very similar. They show clearly that people tend to accept vague and general personality descriptions as uniquely applicable to themselves without realising that the same description could be applied to just about anyone. This is the Forer effect. The name Barnum effect stems from psychologist Paul Meehl, reffering to P.T. Barnum's saying that a good circus should have "a little something for everybody". Still another name used to designate the same phenomenon is subjective validation.

Hope, wishful thinking, vanity and the tendency to try to make sense out of experience are the most common explanations that are used to account for the Barnum effect.

The Barnum effect seems to explain, in part at least, why so many, even highly intelligent, people believe that astrology, cartomancy, chiromancy, numerology, fortune telling, graphology, etc., "work". But scientific studies of these pseudosciences demonstrate that they are not valid personality assessment tools at all. Yet all have many satisfied customers who are convinced they are accurate. Customers will often ignore false or questionable claims. In many cases, by their own words, actions, facial expressions or body language, they will provide most of the information that a pseudoscientific counsellor feeds back to them through skilfull use of cold reading techniques.

Note : This demonstration is different from the original Forer experiment in at least two important ways :

• The "initial personality test" is very poor, not trying to inspire too much confidence,
• Subjects are asked to evaluate every phrase of the personality description instead of the description as a whole.

With this in mind, one must expect that the obtained degree of confidence will be lower than those generally reported.

Note : Please, keep in mind that the measurement of the accuracy of the personality descriptions is but an ordinal scale. The intervals between numbers are not necessarily equal and there is no "true" zero point for this scale. The lowest point on the rating scale used here was arbitrarily chosen to be 1. It could just as well have been 0 or -5. Normally, it would even have been better to calculate the median, instead of the mean. But the point to be made is not the exact number, but a degree of confidence.

• A similar test with a more extensive questionnaire exists on the Internet.
  
  
• Professor Birnbaum's web site for introductory psychology offers a nice summary and a demonstration of the Barnum effect.
  
  
• Professor Dennis Dutton published an excellent article on the net about the Barnum effect and the role it plays in cold reading.
  
  
• The Skeptics Dictionnary, a delightful book by Robert T. Carroll, also offers a very good article about the Forer effect.
  
  
• The Barnum effect is also studied in the field of paranormal psychology.
  
  
• Wikipedia, the free encyclopedia on the Internet, contains, of course, an article about the Forer effect.
  
  
• In a more general way, Google can give you access to lots of interesting information about cold reading,