Déjà vu is is the phenomenon of having the strong sensation that an event or experience currently being experienced has been experienced in the past, whether it has actually happened or not.
The psychologist Edward B. Titchener in his book 1928 A Textbook of Psychology, explained déjà vu as caused by a person having a brief glimpse of an object or situation, before the brain has completed "constructing" a full conscious perception of the experience. Such a "partial perception" then results in a false sense of familiarity. Scientific approaches reject the explanation of déjà vu as "precognition" or "prophecy", but rather explain it as an anomaly of memory, which creates a distinct impression that an experience is "being recalled". This explanation is supported by the fact that the sense of "recollection" at the time is strong in most cases, but that the circumstances of the "previous" experience (when, where, and how the earlier experience occurred) are uncertain or believed to be impossible.
As time passes, subjects may exhibit a strong recollection of having the "unsettling" experience of déjà vu itself, but little or no recollection of the specifics of the event(s) or circumstance(s) which were the subject of the déjà vu experience itself (the events that were being "remembered"). This may result from an "overlap" between the neurological systems responsible for short-term memory and those responsible for long-term memory, resulting in (memories of) recent events erroneously being perceived as being in the more distant past. One theory is the events are stored into memory before the conscious part of the brain even receives the information and processes it.However, this explanation has been criticized that the brain would not be able to store information without a sensory input first. Another theory suggests the brain may process sensory input (perhaps all sensory input) as a "memory-in-progress", and that therefore during the event itself one believes it to be a past memory. In a survey, Brown had concluded that approximately two-thirds of the population have had déjà vu experiences.
The phenomenon is rather complex, and there are many different theories as to why déjà vu happens. Swiss scholar Arthur Funkhouser suggests that there are several "déjà experiences" and asserts that in order to better study the phenomenon, the nuances between the experiences need to be noted. In the examples mentioned above, Funkhouser would describe the first incidence as déjà visité ("already visited") and the second as déjà vecu ("already experienced or lived through").
As much as 70 percent of the population reports having experienced some form of déjà vu. A higher number of incidents occurs in people 15 to 25 years old than in any other age group.
Déjà vu has been firmly associated with temporal-lobe epilepsy. Reportedly, déjà vu can occur just prior to a temporal-lobe epileptic attack. People suffering an epileptic seizure of this kind can experience déjà vu during the actual seizure activity or in the moments between convulsions.
Since déjà vu occurs in individuals with and without a medical condition, there is much speculation as to how and why this phenomenon happens. Several psychoanalysts attribute déjà vu to simple fantasy or wish fulfillment, while some psychiatrists ascribe it to a mismatching in the brain that causes the brain to mistake the present for the past. Many parapsychologists believe it is related to a past-life experience. Obviously, there is more investigation to be done.
In Pop Culture
- Déjà vu provides a plot point in The Matrix, a 1999 science fiction-action film written and directed by Larry and Andy Wachowski. The protagonist, Neo, glances at a black cat and comments that he has just experienced déjà vu. Those with a knowledge of 'The Matrix' and its internal workings state that déjà vu means something within the Matrix was altered from its prior state and is referred to as a "glitch".
- The 2006 science fiction film Déjà Vu revolves around a US federal law enforcement officer, played by Denzel Washington, using an instrument called Snowhite to view the past four and a half days of anywhere in the world (limited radius as permissible by the program) in order to solve a murder and a terrorist bomb attack on a ferry that was being boarded by about 500 citizens and military members.
- The X-Files episode "Monday" (Season 6, Episode 14) in which Mulder and Scully repeat the same day again and again explores the complexities of déjà vu. In the episode Mulder uses his experience of déjà vu to influence events.
- The final episode of season 1 of Charmed, called "Déjà Vu All Over Again" sees Phoebe Halliwell reliving the same day over and over again at the hands of a demon named Tempus
- In episode 6 of The Suite Life On Deck Cody keeps repeating the same day over and over again when the ship is struck with lightning when crossing the international dateline
- The latest instalment in the Metal Gear Solid series, Metal Gear Solid V: The Phantom Pain features console exclusive missions called "Deja Vu" and "Jamais Vu" respectively. The Deja Vu Mission features the protagonist Solid Snake from the first Metal Gear Solid game while the Jamais Vu Mission features a cyborg named Raiden from Metal Gear Rising, the previous entry in the Metal Gear continuity.
- Déjà vu is an achievement/trophy in Assassins Creed: Brotherhood.
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