The deja vu experience: remembrance of things past? The deja vu experience is a common phenomenon, occurring in pathological as well as nonpathological conditions. It has been defined as any subjectively inappropriate impression of familiarity of a present experience with an undefined past. The authors discuss the epidemiologic data, clinical features, and etiology of the phenomenon of deja vu. They also review the different hypotheses on the psychopathogenesis of the deja vu experience and introduce an explanation based on the hologram as a mnestic model. 