Barnum effect

The Barnum effect, also called the Forer effect, 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, aura reading and some types of personality tests.

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, expectation, or hypothesis demands a relationship. For example, while reading it, people actively 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 psychology test—his Diagnostic Interest Blank—to a group of his psychology students who were told that they would each receive a brief personality vignette or sketch based on their test results. One week later Forer gave each student a purportedly individualized sketch and asked each of them to rate it on how well it applied. In reality, each student received the same sketch, consisting of the following items: