True-believer syndrome is an informal or rhetorical term coined by M. Lamar Keene in his 1976 book The Psychic Mafia. He began using the term to refer to people who continued to believe in a paranormal phenomenon or event, even after it had successfully been debunked or proven to have been staged.[1][2] Keene considered it to be a cognitive disorder,[3][4] and regarded it as being a key factor in the success of many psychic mediums.[2]
The term "true believer" had earlier been used by Eric Hoffer in his 1951 book The True Believer to describe the psychological roots of fanatical groups.
True-believer syndrome could be considered a type of belief perseverance for paranormal phenomena.