A fixed fantasy is a belief or system of beliefs held by an individual to be genuine, but that cannot be verified in reality. The term is typically applied to individuals suffering from some type of psychiatric dysregulation, most often a personality disorder. Psychiatry is a branch of medicine that studies and treats mental and emotional disorders (see mental illness). ... Emotional dysregulation (or affect dysregulation) is a term used in the mental health community to refer to an emotional response that is not well modulated. ... Personality disorders form a class of mental disorders that are characterized by long-lasting rigid patterns of thought and actions. ...

A fixed fantasy differs from a delusion or delusional system in that, superficially, a fixed fantasy tends to appear plausible, and the person expressing the fantasy is not suffering a break from reality, as occurs in a delusional state. A delusion is commonly defined as a fixed false belief and is used in everyday language to describe a belief that is either false, fanciful or derived from deception. ...

A fixed fantasy also differs from a superstition in that superstitions are culturally bound, whereas a fixed fantasy is specific to an individual. The number 13 is often avoided in public buildings, also floors, doors and this Santa Anita Park horse stall. ...

In and of themselves, fixed fantasies are typically not harmful, but they can sometimes interfere with an individuals' ability to develop a coherent and integrated life experience.