Déjà vu, (i/ /) from French, literally "already seen", 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 A Textbook of Psychology (1928), 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. Other studies confirm that déjà vu is a common experience in healthy individuals, with between 31% and 96% of individuals reporting it. Déjà vu experiences that are unusually prolonged or frequent, or in association with other symptoms such as hallucinations, may be an indicator of neurological or psychiatric illness.
Links with disorders
Early researchers tried to establish a link between déjà vu and serious mental disorders such as schizophrenia, anxiety, and dissociative identity disorder, but failed to find correlations of any diagnostic value. There does not seem to be a special association between déjà vu and schizophrenia or other psychiatric conditions. The strongest pathological association of déjà vu is with temporal lobe epilepsy. This correlation has led some researchers to speculate that the experience of déjà vu is possibly a neurological anomaly related to improper electrical discharge in the brain. As most people suffer a mild (i.e. non-pathological) epileptic episode regularly (e.g. a hypnagogic jerk, the sudden "jolt" that frequently, but not always, occurs just prior to falling asleep), it is conjectured that a similar (mild) neurological aberration occurs in the experience of déjà vu, resulting in an erroneous sensation of memory. Scientists have even looked into genetics when considering déjà vu. Although there is not currently a gene associated with déjà vu, the LGII gene on chromosome 10 is being studied for a possible link. Certain forms of the gene are associated with a mild form of epilepsy and, though by no means a certainty, déjà vu occurs often enough during seizures that researchers have reason to suspect a link.
Certain drugs increase the chances of déjà vu occurring in the user. Some pharmaceutical drugs, when taken together, have also been implicated in the cause of déjà vu. Taiminen and Jääskeläinen (2001) reported the case of an otherwise healthy male who started experiencing intense and recurrent sensations of déjà vu upon taking the drugs amantadine and phenylpropanolamine together to relieve flu symptoms. He found the experience so interesting that he completed the full course of his treatment and reported it to the psychologists to write up as a case study. Due to the dopaminergic action of the drugs and previous findings from electrode stimulation of the brain (e.g. Bancaud, Brunet-Bourgin, Chauvel, & Halgren, 1994), Taiminen and Jääskeläinen speculate that déjà vu occurs as a result of hyperdopaminergic action in the mesial temporal areas of the brain.
The similarity between a déjà-vu-eliciting stimulus and an existing, but different, memory trace may lead to the sensation. Thus, encountering something which evokes the implicit associations of an experience or sensation that cannot be remembered may lead to déjà vu. In an effort to experimentally reproduce the sensation, Banister and Zangwill (1941) used hypnosis to give participants posthypnotic amnesia for material they had already seen. When this was later re-encountered, the restricted activation caused thereafter by the posthypnotic amnesia resulted in three of the 10 participants reporting what the authors termed "paramnesias". Memory-based explanations may lead to the development of a number of non-invasive experimental methods by which a long sought-after analogue of déjà vu can be reliably produced that would allow it to be tested under well-controlled experimental conditions. Cleary suggests that déjà vu may be a form of familiarity-based recognition (recognition that is based on a feeling of familiarity with a situation) and that laboratory methods of probing familiarity-based recognition hold promise for probing déjà vu in laboratory settings. A recent study that used virtual reality technology to study reported déjà vu experiences supported this idea. This virtual reality investigation suggested that similarity between a new scene's spatial layout and the layout of a previously experienced scene in memory (but which fails to be recalled) may contribute to the déjà vu experience. When the previously experienced scene fails to come to mind in response to viewing the new scene, that previously experienced scene in memory can still exert an effect—that effect may be a feeling of familiarity with the new scene that is subjectively experienced as a feeling of déjà vu, or of having been there before despite knowing otherwise. Another possible explanation for the phenomenon of déjà vu is the occurrence of "cryptomnesia", which is where information learned is forgotten but nevertheless stored in the brain, and similar occurrences invoke the contained knowledge, leading to a feeling of familiarity because of the situation, event or emotional/vocal content, known as "déjà vu". Some experts suggest that memory is a process of reconstruction, rather than a recall of fixed, established events. This reconstruction comes from stored components, involving elaborations, distortions and omissions. Each successive recall of an event is merely a recall of the last reconstruction. The proposed sense of recognition (déjà vu) involves achieving a good ‘match’ between the present experience and our stored data. This reconstruction however, may now differ so much from the original event that we ‘know’ we have never experienced it before, even though it seems similar.
Jamais vu (from French, meaning "never seen") is a term in psychology which is used to describe any familiar situation which is not recognized by the observer.
Often described as the opposite of déjà vu, jamais vu involves a sense of eeriness and the observer's impression of seeing the situation for the first time, despite rationally knowing that he or she has been in the situation before. Jamais vu is more commonly explained as when a person momentarily does not recognize a word, person, or place that they already know. Jamais vu is sometimes associated with certain types of aphasia, amnesia, and epilepsy.
Theoretically, as seen below, a jamais vu feeling in a sufferer of a delirious disorder or intoxication could result in a delirious explanation of it, such as in the Capgras delusion, in which the patient takes a person known by him or her for a false double or impostor. If the impostor is himself, the clinical setting would be the same as the one described as depersonalisation, hence jamais vus of oneself or of the very "reality of reality", are termed depersonalisation (or surreality) feelings.
Times Online reports (see semantic satiation):
Chris Moulin, of the University of Leeds, asked 95 volunteers to write out "door" 30 times in 60 seconds. At the International Conference on Memory in Sydney last week he reported that 68 percent of the volunteers showed symptoms of jamais vu, such as beginning to doubt that "door" was a real word. Dr. Moulin believes that a similar brain fatigue underlies a phenomenon observed in some schizophrenia patients: that a familiar person has been replaced by an impostor. Dr. Moulin suggests they could be suffering from chronic jamais vu.
In popular culture
- Déjà vu provides a plot point in The Matrix, a 1999 science fiction-action film written and directed by The Wachowskis. 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, which is referred to as a "glitch".
- The 2006 science fiction film Déjà Vu revolves around a US Federal ATF agent, played by Denzel Washington, using an instrument called Snowhite to look four days and six hours into the past, to investigate a Mardi Gras ferry bombing that killed over 400 military personnel and family members in New Orleans.
- In the 2011 film Donovan’s Echo, the central character, Donovan (Danny Glover), experiences a series of déjà vu events 30 years apart. His sanity is in question when he strongly begins to believe that the same set of events that led to his family's death is happening to a young girl and her mother.
- In the 2013 Japanese animated film Steins;Gate: Fuka Ryōiki no Déjà vu, the character Rintarou Okabe begins to feel the effects of traveling through multiple alternate realities ("World Lines"), and eventually fades out of existence. Only one person, Kurisu Makise, remembers Rintarou due to déjà vu, and must find a way to bring him back.
- GroundHog Day (Bill Murray)
- Déjà Vu was the third episode of the second season of Monty Python's Flying Circus, a British comedy program. Michael Palin plays a television host with the problem.
- The concept is explored in the episode 119 of Garfield and Friends in the Orson's Farm segment.
- 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.
- Déjà vu is a recurring plot element on Fringe. In the Season One episode, "The Road Not Taken," Olivia described the experience of déjà vu to Walter after she briefly experienced an alternate reality as the result of being a Cortexiphan subject. In the Season Two episode "White Tulip," Olivia experiences déjà vu while investigating the apartment of a time traveler who reset the timeline.
- Déjà vu is a plot element in the episode "Mystery Spot" of the television series Supernatural, where Sam Winchester keeps waking up in the same day as a result of being trapped in a time loop.
- In episode 6 of The Suite Life On Deck, Cody keeps repeating the same day over and over again when the ship is struck by lightning while crossing the International Date Line.
- In the Star Trek: The Next Generation episode, ‘Cause and Effect,’ The USS Enterprise is destroyed in a collision with another ship, near a temporal anomaly. This causes the event to repeat over and over, which in turn causes several crew members to have feelings of déjà vu.
- In the Stargate SG-1 episode "Window of Opportunity," Teal'c and O'Neill experience the same day over and over again due to a device on an alien planet.
- In a Season 2 episode of Ed, Edd n Eddy, Kevin is sitting with the kids to watch Eddy's telethon, and says "Déjà vu."
- In Catch-22 by Joseph Heller, the narrator references Déjà vu, Jamais vu and Presque vu via the Chaplain Tappman's internal dialog: "It was not jamais vu, since the apparition was not of someone, or something, familiar appearing to him in an unfamiliar guise. And it was certainly not presque vu, for the chaplain did see him…" 
- The experience also can be noticed in books such as Guy Mannering or the Astrologer (1815), by sir Walter Scott, and Our Old Home: A Series of English Sketches (1863), by Nathaniel Hawthorne.
- Déjà Vu is a 2009 radio play by Alexis Zegerman in French and English co-produced by BBC Radio 4 and ARTE Radio.
Sonic Generations is a game in the Sonic franchise by SEGA in which Sonic and his friends are sent to a timeless place where the characters begin having déjà vu before realising what was happening to time and their current predicament, seeing places and enemies from their past.
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- "The Meaning of Déjà Vu", Eli Marcovitz, M.D. (1952). Psychoanalytic Quarterly, vol. 21, pages: 481-489
- The déjà vu experience, Alan S. Brown, Psychology Press, (2008), ISBN 0-203-48544-0, Introduction, page 1
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- Neurology Channel
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- Brynie, Faith (2009). Brain Sense: The Science of the Senses and How We Process the World Around Us. Amacom. p. 195.
- Taiminen, T.; Jääskeläinen, S. (2001). "Intense and recurrent déjà vu experiences related to amantadine and phenylpropanolamine in a healthy male". Journal of Clinical Neuroscience 8 (5): 460–462. doi:10.1054/jocn.2000.0810. PMID 11535020.
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- Mental Status Examination Rapid Record Form
- "Monty Python's Flying Circus: Just the Words - Episode 16". Ibras.dk. Retrieved 2012-03-23.
- Déjà Vu All Over Again at the Internet Movie Database
- Catch-22 Absurdity Quotes Page 7
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- Draaisma, Douwe (2004). Why life speeds up as you get older. Cambridge University Press. ISBN 0-521-69199-0.
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- Ratliff, Evan (2006-07-02). "Déjà Vu, Again and Again". New York Times. Retrieved 2010-05-01.
- "When déjà vu is more than just an odd feeling". The Ottawa Citizen. 2006-02-20.
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- Herbert, Wray (2008-10-23). "And I feel like I've been here before". Psychological Science.
- McHugh TJ, Jones MW, Quinn JJ et al. (July 2007). "Dentate gyrus NMDA receptors mediate rapid pattern separation in the hippocampal network". Science 317 (5834): 94–9. doi:10.1126/science.1140263. PMID 17556551.
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