Barnum effect
The tendency to accept vague, general descriptions as personal and accurate, as in horoscopes and personality tests.
Also: Forer effect, subjective validation
In 1948 psychologist Bertram Forer gave his students a personality sketch and asked them to rate how well it fitted them. They gave it an average of 4.26 out of 5, not knowing that all had received the same text, which he had assembled from astrology books. Paul Meehl later named it the Barnum effect after the showman P. T. Barnum, said to offer something for everyone. The effect is stronger when the description is flattering, when the reader believes it was made for them, and when the source seems authoritative. It helps explain why horoscopes and some readings seem personal, and why sceptics recommend checking a reading against a stranger's.