Forer Effect or Barnum Effect

The Forer effect is the observation that individuals ascribe a high level of accuracy to statements and personality descriptions that are supposedly tailored just for them but which are, in fact, generic and equally applicable to just about anybody. An example of the effect can be seen in those people who believe strongly in certain practices such as astrology and fortune telling. In these practices, a person is given a statement that is supposedly tailored just for that particular individual and his or her particular life history. Because the individual believes that the message is meant only for them, the accuracy and the importance of the message is amplified even though, in reality, the message has been prepared with the intent of being generalized and vague enough so that many people may believe that it applies to them. The term Forer effect is named after the psychologist Bertram R. Forer, who, in 1948, gave his students a personality test in which they were told that they were each receiving a unique personality assessment based on a personality test that they were given. Each student was asked to rate the accuracy of the personality assessment on a scale from 0 (very poor) to 5 (excellent). On average, Forer’s students rated the accuracy of their “personal” personality assessment as a score of 4.26 out of 5.00. It was later revealed that each student had not received a personalized personality assessment, but had rather received identical copies of a general personality description, which Forer had assembled from various horoscopes.

Source:

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.