The true-believer syndrome is a term coined by the reformed psychic fraud M. Lamar Keene to refer to an irrational belief in the paranormal. Skeptics see this as a form of self-deception caused by wishful thinking in which a believer continues to accept paranormal explanations for phenomena or events, or denies the relevance of scientific findings, even after the believer has been confronted with abundant evidence that the phenomena or events have natural causes. The term is mainly used by skeptics in the debate over the existence of certain sorts of paranormal phenomena and the persistence of belief in these phenomena.
For example, skeptics generally agree there is sufficient proof to conclude that the alleged miracles of Uri Geller, Sathya Sai Baba and Jim Jones are or were false; they therefore have often reasoned that believers who have been given the extant evidence of fraud in these cases, and yet continue to believe in these men, are described by this condition. Some ex-followers of Sathya Sai Baba accept this syndrome as an explanation of what has happened to them., 
Robert T. Carroll, the webmaster of the skeptic's dictionary, sees some similarity with a pathological delusion.
The term was not coined by mainstream psychologists, is not used in the scientific literature, has not been included in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders. No clinical evidence has been provided for its links with demonstrable cognitive impairment or psychopathology.
Similar belief processes were studied by Thomas Kuhn. In his study on the sociology of science, The Structure of Scientific Revolutions Kuhn demonstrates that scientists can hold onto beliefs in scientific theories despite overwhelming prevailing counter-evidence, and suggested that social forces, as much as ones purely concerned with rationality, are a strong influence on the beliefs we hold. This is an area studied by the sociology of knowledge where the social function of paranormal beliefs has been a focus of research.