What is Déjà vu?

   Déjà vu is French for "already seen," déjà vu refers to the common sensation that one has experienced a situation, scene or sequence of events previously. Such sensations are usually accompanied by a greatly heightened consciousness and the conviction that one can actually predict what will happen next. While the experience seems to provoke anxiety in some people, others respond to it with delight, whether the scene involves familiar material and characters or, as is equally common, is in a place or from a time of which the per­cipient has no knowledge, such as when a first-time traveler in a foreign country unexpectedly comes upon a village that he recognízes in every detail. On his first trip to Africa, Cari G. Jung had such an experience: staring out the window of a train, he spotted a solitary tribesman standing on a cliff. "It was," he wrote, "as if I were this moment returning to the land of my youth, and as if I knew that dark-skinned man... had been waiting for me for five thousand years." Jung termed his experience "recognition of the immemorially known."
   A great many theories have been proposed to explain déjà vu  but no sin­gle one has gained wide acceptance, and no medical proof has ever been offered to explain it biologically, although Arthur Wigan suggested in 1884 that the phenomenon could be the result of the fact that one hemisphere of the brain registers data a fraction of a second sooner than the other. A related theory. proposed by Frederic W. H. Myers in 1895, is that the unconscious, or subliminal consciousness, acknowledges events an instant sooner than the con­scious brain.
   Other possible explanations that have been seriously advanced are that déjà vu results from one or another form of ESP—clairvoyance, telepathy, precognition or precognitive dreams; that it is proof of reincarnation, or that it is evidence of prenatal consciousness, being based on memories of experiences of one's mother and not oneself.