Tuesday, April 03, 2012

What Is Déjà Vu?


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Déjà vu (French pronunciation: [deʒa vy] ( listen), literally "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 prior 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.[1]

Contents

 

 Scientific research

The psychologist Edward B. Titchener in his book A Textbook of Psychology (1928), wrote that déjà vu is caused by a person getting a brief glimpse of an object or situation prior to full conscious perception, resulting in a false sense of familiarity.[2] The explanation that has mostly been accepted of déjà vu is not that it is an act of "precognition" or "prophecy", but rather that it is an anomaly of memory, giving the false impression that an experience is "being recalled".[3][4] 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 quite uncertain or believed to be impossible. Likewise, as time passes, subjects can 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) they were "remembering" when they had the déjà vu experience. In particular, this may result from an overlap between the neurological systems responsible for short-term memory and those responsible for long-term memory (events which are perceived as being in the past). The events would be stored into memory before the conscious part of the brain even receives the information and processes it.[citation needed]

 Links with disorders

Early researchers tried to establish a link between déjà vu and serious psychopathology such as schizophrenia, anxiety, and dissociative identity disorder, and failed to find the experience of some diagnostic value. There does not seem to be a special association between déjà vu and schizophrenia or other psychiatric conditions.[5] The strongest pathological association of déjà vu is with temporal lobe epilepsy.[6][7] 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.

 Pharmacology

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)[8] 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),[9] Taiminen and Jääskeläinen speculate that déjà vu occurs as a result of hyperdopaminergic action in the mesial temporal areas of the brain.

 Memory-based explanations

The similarity between a déjà-vu-eliciting stimulus and an existing, but different, memory trace may lead to the sensation.[5][10] 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)[11][12] 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[10] 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. 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".

 Parapsychology

Some parapsychologists have advocated some unorthodox interpretations of déjà vu. Ian Stevenson and a minority of other researchers have written that some cases of déjà vu might be explained on the basis of reincarnation.[13][14] Anthony Peake has written that déjà vu experiences occur as people are living their lives not for the first time but at least the second.[15]

 Related phenomena

 Jamais vu

Main article: Jamais vu
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.[16]

 Presque vu (Tip of the tongue)

Main article: Tip of the tongue
Déjà vu is similar to, but distinct from, the phenomenon called tip of the tongue, a situation when someone cannot recall a familiar word or name, but with effort one eventually recalls the elusive memory. In contrast, déjà vu is a feeling that the present situation has occurred before, but the details are elusive because the situation never happened before.
Presque vu (from French, meaning "almost seen") is the sensation of being on the brink of an epiphany. Often very disorienting and distracting, presque vu rarely leads to an actual breakthrough. Frequently, one experiencing presque vu will say that they have something "on the tip of my tongue".

 Déjà entendu

Déjà entendu, (literally "already heard") is the experience of feeling sure that one has already heard something, even though the exact details are uncertain and were perhaps imagined.[17][18]

 Reja vu

The feeling something that has happened or is happening will happen again, possibly in the near future, possibly in the distant future.

 In popular culture

 Film

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 using an instrument called Snowhite to view the past 4 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.

 Television

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.[19]
The concept is explored in the episode 119 of Garfield and Friends in the Orson's Farm segment.
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.[20]
Déjà Vu is also 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 also a plot element in the "Mystery Episode" of the television series Supernatural where Sam Winchester wakes up in the same day as a result of being trapped in a time loop.

 Radio

Déjà Vu is a 2009 radio play by Alexis Zegerman in French and English co-produced by BBC Radio 4 and ARTE Radio.

  Theatre

Déjà Vu is a 1991 stage play by John Osborne.

 Music

Below is a list of artists who have referenced Déjà Vu in their work.
Main article: Déjà_vu_(disambiguation)#Music

 See also

 References

  1. ^ Berrios, G.E. (1995). "Déjà vu and other disorders of memory during the nineteenth century". Comprehensive Psychiatry 36: 123–129.
  2. ^ Titchener, E. B. (1928). A textbook of psychology. New York: Macmillan
  3. ^ "The Meaning of Déjà Vu", Eli Marcovitz, M.D. (1952). Psychoanalytic Quarterly, vol. 21, pages: 481-489
  4. ^ The déjà vu experience, Alan S. Brown, Psychology Press, (2004), ISBN 0-203-48544-0, Introduction, page 1
  5. ^ a b Brown, Alan S. (2004). The Déjà Vu Experience. Psychology Press. ISBN 1841690759.
  6. ^ Neurology Channel
  7. ^ Howstuffworks "What is déjà vu?"
  8. ^ 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. edit
  9. ^ Bancaud, J.; Brunet-Bourgin; Chauvel; Halgren (1994). "Anatomical origin of déjà vu and vivid 'memories' in human temporal lobe epilepsy". Brain : a journal of neurology 117 (1): 71–90. PMID 8149215. edit
  10. ^ a b Cleary, Anne M. (2008). "Recognition memory, familiarity and déjà vu experiences". Current Directions in Psychological Science 17 (5): 353–357. doi:10.1111/j.1467-8721.2008.00605.x.
  11. ^ Banister H, Zangwill OL (1941). "Experimentally induced olfactory paramnesia". British Journal of Psychology 32: 155–175.
  12. ^ Banister H, Zangwill OL (1941). "Experimentally induced visual paramnesias". British Journal of Psychology 32: 30–51.
  13. ^ Fisher, J. (1984). The case for reincarnation. New York: Bantam Books.
  14. ^ Stevenson, I. (1987). Children who remember past lives. Charlottesville, VA: University Press of Virginia.
  15. ^ Anthony Peake Is There Life After Death? The Extraordinary Science of What Happens When We Die Arcturus Publishing Limited, 2012 ISBN 184837299X
  16. ^ Ahuja, Anjana (2006-07-24). "Doctor, I've got this little lump on my arm . . . Relax, that tells me everything". London: Times Online. Retrieved 2010-05-01.
  17. ^ Grinnel, Renée (2008), Déjà Entendu, PsychCentral, retrieved 04-10-2011
  18. ^ Mental Status Examination Rapid Record Form
  19. ^ "Monty Python's Flying Circus: Just the Words - Episode 16". Ibras.dk. Retrieved 2012-03-23.
  20. ^ http://www.imdb.com/title/tt0539356/

 Further reading

 External links

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See Also:



First came the heterodyne. The principle of "beats" or difference tones between simultaneous audio pitches was well known since antiquity, but Reginald Fessenden in 1901 was the first to apply the principle to radio transmissions [3]. Originally both radio frequencies were to be transmitted, received with two antennas, and combined in a detector. Later a local oscillator was substituted for one of the transmitter-receiver combinations and the heterodyne as we know it was born. Fessenden himself coined the term, from the Greek heteros (other) and dynamis (force).Who Invented the Superheterodyne?
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