Paramnesia or Promnesia, better know commonly as "Deja vu" is the experience of feeling sure that one has witnessed or experienced a new situation previously (an individual feels as though an event has already happened or has happened in the near past).
The experience of Deja vu is usually accompanied by a compelling sense of familiarity, and also a senses of:
"eeriness," "strangeness," or "weirdness,"
The "previous" experience is most frequently attributed to real life, although in some cases there is a firm sense that the experience "genuinely happened" in the past.
The experience of Deja vu seems to be quite common among adults and children alike; in formal studies, 70% of people report having experienced it at least once.
References to the experience of Deja vu are also found in literature of the past indicating it is not a new phenomenon.
It has been extremely difficult to evoke the Deja vu experience in laboratory settings, therefore making it a subject of little or few empirical studies.
Recently, researchers have found ways to recreate this sensation using hypnosis.
(This reply intended as an informational but not definitive guide based on current scientific theories).