巴纳姆效应（英语：Barnum effect，是Paul Meehl为表对费尼尔司·泰勒·巴纳姆的敬意而命名，又称巴南效应、佛瑞效应 (英语：Forer effect)）是一种心理现象，人们会对于他们认为是为自己量身订做的一些人格描述给予高度准确的评价，而这些描述往往十分模糊及普遍，以致能够放诸四海皆准适用于很多人身上。巴纳姆效应能够对于为何不少伪科学如占星学、占卜或心理测验等被普遍接受提供一个不十分完全的解释。

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.