Psychologist Bertram R. Forer, (1914—2000), ran a series of tests in which he gave people a personality profile and asked them to rate its accuracy. Forer actually gave each person the exact same profile:
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. 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.
This assessment was created by combining snippets of horoscope readings. It demonstrates how easily people can be led to believe that their personality is being accurately assessed when it clearly is not.
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. 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. A number of the statements that could apply equally to anyone.
The test was repeated many times, with an average of about 85% of people rating the personality profile as very accurate. Remember that each person received exactly the same profile as everyone else.
The Forer Effect can explain why so many "pseudosciences" continue to flourish, despite having a questionable validity. When a person starts off with hope or expectation that the astrology, biorhythm, rune stones, tarot, (or hands) will reveal "special" details about them, they're much more ready to believe the words and advice. Something general is mentioned, and the information is taken as specific and personal. This seems to be just another part of human nature, but a tendency we need to be aware of.
For psychics and other new age professionals, this means that the wonderfully positive feedback received from numerous repeat clients could still be nothing more than the Forer Effect and wishful thinking. And then the more you hear how good you are, the more you believe it, and the more practice you get at giving readings that produce the same positive feedback (like, perhaps 85% or so....). This is the Subjective Validation Effect. Theoretically, you could be harming every client and yet believe you were doing Divinely inspired work. Generalizations are commonly used by "Cold readers".
The Forer effect shows that people tend to accept generalised descriptions of their personalities without realising that the same evaluation could apply to nearly anyone else, because people want the results to be true.