Déjà vu (French pronunciation: [deʒa vy] ( listen), meaning “already seen”) is the experience of feeling sure that one has already witnessed or experienced a current situation, even though the exact circumstances of the previous encounter are uncertain and were perhaps imagined. The term was coined by a French psychic researcher, Émile Boirac (1851–1917) in his book L’Avenir des sciences psychiques (“The Future of Psychic Sciences”), which expanded upon an essay he wrote while an undergraduate. The experience of déjà vu is usually accompanied by a compelling sense of familiarity, and also a sense of “eeriness,” “strangeness,” “weirdness,” or what Sigmund Freud calls “the uncanny.” The “previous” experience is most frequently attributed to a dream, although in some cases there is a firm sense that the experience has genuinely happened in the past.
The experience of déjà vu seems to be quite common among adults and children alike. References to the experience of déjà vu are found in literature of the past, indicating it is not a new phenomenon. It has been extremely difficult to evoke the déjà vu experience in laboratory settings, therefore making it a subject of few empirical studies. Certain researchers claim to have found ways to recreate this sensation using hypnosis.