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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 religion, astrology, fortune telling, graphology, and some types of personality test.
A related and more general phenomenon is that of subjective validation. Subjective validation occurs when two unrelated or even random events are perceived to be related because a belief, expectancy, or hypothesis demands a relationship. Thus people seek a correspondence between their perception of their personality and the contents of a horoscope.
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. As can be seen from the profile, there are a number of statements that could apply equally to anyone.
In another study examining the Forer effect, students took the MMPI personality assessment and researchers evaluated their responses. The researchers wrote accurate evaluations of the students’ personalities, but gave the students both the accurate assessment and a fake assessment using vague generalities. Students were then asked to choose which personality assessment they believe was their own, actual assessment. More than half of the students (59%) chose the fake assessment as opposed to the real one.
The Forer effect is also known as the "Barnum effect". This term was coined in 1956 by American psychologist Paul Meehl in his essay "Wanted - A Good Cookbook". He relates the vague personality descriptions used in certain "pseudo-successful" psychological tests to those given by entertainer and businessman P. T. Barnum, who was a notorious hoaxer.
Repeating the study 
Two factors are important in ensuring that the study is replicable. The content of the description offered is important, with specific emphasis on the ratio of positive to negative trait assessments. The other important factor is that the subject trusts the person who is giving feedback to give them feedback based on honest and subjective assessment.
The effect is so consistent because the statements are so vague. People are able to read their own meaning into the statements they receive, and thus, the statement becomes "personal" to them. The most effective statements contain statements based around the phrase: "at times." Such as: "At times you feel very sure of your self, while at other times you are not as confident." This phrase can apply to almost anybody, and thus each person can read their own meaning into it. Keeping statements vague in this manner will ensure high rates of reliability when repeating the study.
In 2011, the study was repeated with the statements altered so that they applied to organisations rather than individuals. The results were similar suggesting that people anthropomorphize organisations and are gullible when it comes to interpreting their characters.
Variables influencing the effect 
Studies have shown that the Forer effect is seemingly universal - it has been observed in people from many different cultures and geographic locations. In 2009, psychologists Paul Rogers and Janice Soule conducted a study that compared the tendencies of Westerners to accept Barnum personality profiles to the tendencies of Chinese people. They were unable to find any significant differences.
However, 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, and thus applies their own meaning to the statements.
- 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.
Sex has also proven to play a role in how accurate the subject believes the description to be: women are more likely than men to believe that the vague statement is accurate.
The method in which the Barnum personality profiles are presented can also affect the extent to which people accept them as their own. For instance, Barnum profiles that are more personalized - perhaps containing a specific person's name - are more likely to yield higher acceptability ratings than those that could be applied to anyone.
Recent research 
Belief in the paranormal 
There is evidence that having prior belief in the paranormal leads to greater influence of the effect. Subjects who, for example, believe in the accuracy of horoscopes have a greater tendency to believe that the vague generalities of the response apply specifically to them. Other examples of beliefs in the paranormal include belief in magical powers, spiritual happenings, or other influences. Studies on the relationship between schizotypy and belief in the Forer effect have shown high amounts of correlation. However, Rogers and Soule's 2009 study (see "Variables Influencing the Effect" above) also tested subjects' astrological beliefs, and both the Chinese and Western skeptics were more likely to identify the ambiguity within the Barnum profiles. This suggests that individuals who do not believe in astrology are possibly influenced less by the effect.
Self-serving bias 
Self-serving bias has been shown to cancel the Forer effect. According to the self-serving bias, subjects accept positive attributes about themselves while rejecting negative ones. In one study, subjects were given one of three personality reports. One contained Barnum profiles with socially desirable personality traits, one contained profiles full of negative traits (also called "common faults"), and the last contained a mixture of the two. Subjects who received the socially desirable and mixed reports were far more likely to agree with the personality assessments than the subjects who received negative reports, though it should be noted that there was not a significant difference between the first two groups. In another study, subjects were given a list of traits instead of the usual "fake" personality assessment. The subjects were asked to rate how much they felt these traits applied to them. In line with the self-serving bias, the majority of subjects agreed with positive traits about themselves, and disagreed with negative ones. The study concluded that the self-serving bias is powerful enough to cancel out the usual Forer effect.
In popular culture 
A similar experiment was made during the second episode of the seventh season of the TV show Penn & Teller: Bullshit! The episode was about astrology, and also discussed confirmation bias. The results were similar to Forer's study.
A version of the original experiment was performed by illusionist Derren Brown, in the first episode of series 3 of his television series Trick of the Mind. He described the experiment in his book, Tricks of the Mind.
The effect was referenced in the 16th episode of Season 1 of the sitcom The Big Bang Theory.
See also 
- Marks, David F (2000). The Psychology of the Psychic (2 ed.). Amherst, New York: Prometheus Books. p. 41. ISBN 1-57392-798-8.
- Forer, B.R. (1949). "The fallacy of personal validation: A classroom demonstration of gullibility". Journal of Abnormal and Social Psychology (American Psychological Association) 44 (1): 118–123. doi:10.1037/h0059240.
- Cline, Austin. "Flaws in Reasoning and Arguments: Barnum Effect & Gullibility". About.com. Retrieved 12 November 2012.
- Meehl, Paul (1956). Wanted - A Good Cookbook (The American Psychologist). p. 266.
- Dutton, Denis. "The Cold Reading Technique". Retrieved 28 November 2012.
- Claridge, G; Clark, K., Powney, E., & Hassan, E. (2008). "Schizotypy and the Barnum effect.". Personality and Individual Differences. 44 (2): 436–444.
- "Something for Everyone - The Barnum Effect". The Articulate CEO. Retrieved 25 November 2012.
- Krauss-Whitbourne, Susan. "When it comes to personality tests, skepticism is a good thing.". Psychology Today. Retrieved 25 November 2012.
- Nolan, Stuart. "The Forer Scam". TEDxSalford. Retrieved 25 March 2013.
- Rogers, Paul; Janice Soule (2009). "Cross-Cultural Differences in the Acceptance of Barnum Profiles Supposedly Derived From Western Versus Chinese Astrology". Journal of Cross-Cultural Psychology. Retrieved 2012-11-11.
- Dickson, D.H.; Kelly, I.W. (1985). "The 'Barnum Effect' in Personality Assessment: A Review of the Literature". Psychological Reports (Missoula) 57 (1): 367–382. ISSN 0033-2941. OCLC 1318827.
- Piper-Terry, M.L.; Downey, J.L. (1998). "Sex, gullibility, and the Barnum effect". Psychological Reports 82: 571–575.
- Farley-Icard, Roberta Lynn (2007). Factors that influence the Barnum Effect: Social desirability, base rates and personalization.
- "Balance-Today - Astroology". Retrieved 28 November 2012.
- MacDonald, D.J.; Standing, L.G. (2002). "Does self-serving bias cancel the Barnum effect?". Social behavior and personality 30 (6): 625–630.