[Alliopeti]

I am not commenting particularly on Myers-Briggs, but I think the Forer Effect is relevant here. I remember reading some years ago where a version of this was used in a class room exercise on astrology or some such. I cannot remember who ran it but it may have been James Randi.

Lightly edited version of Wikipedia on Forer Effect:

The Forer effect (also called the Barnum Effect after P.T. Barnum's observation that "we've got something for everyone") is the observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. This effect can provide a partial explanation for the widespread acceptance of some beliefs and practices, such as astrology, fortune telling, graphology, and some types of personality tests.
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Forer's demonstration

In 1948, psychologist Bertram R. Forer gave a personality test to his students. He told his students they were each receiving a unique personality analysis that was based on the test's results and to rate their analysis on a scale of 0 (very poor) to 5 (excellent) on how well it applied to themselves. In reality, each received the same analysis:

“ You have a great need for other people to like and admire you. You have a tendency to be critical of yourself. You have a great deal of unused capacity which you have not turned to your advantage. While you have some personality weaknesses, you are generally able to compensate for them. Your sexual adjustment has presented problems for you. Disciplined and self-controlled outside, you tend to be worrisome and insecure 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 pride yourself as an independent thinker and do not accept others' statements without satisfactory proof. You have found it unwise to be too frank in revealing yourself to others. At times you are extroverted, affable, sociable, while at other times you are introverted, wary, reserved. Some of your aspirations tend to be pretty unrealistic. Security is one of your major goals in life. ”

On average, the rating was 4.26, but only after the ratings were turned in was it revealed that each student had received identical copies assembled by Forer from various horoscopes.[2] As can be seen from the profile, there are a number of statements that could apply equally to anyone. These statements later became known as Barnum statements, after P.T. Barnum.

Variables influencing the effect

Later studies have found that subjects give higher accuracy ratings if the following are true:

the subject believes that the analysis applies only to him or her[clarification needed]
the subject believes in the authority of the evaluator
the analysis lists mainly positive traits

See Dickson and Kelly for a review of the literature.[3]