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Déjà vu: Difference between revisions

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'''Déjà vu''' ({{pron-en|ˈdeɪʒɑː ˈvuː|en-uk-dejavu.ogg}}; {{IPA-fr|deʒa vy|lang|fr-déjà vu.ogg}}, "already seen"; also called '''[[Reduplicative paramnesia|paramnesia]],''' from Greek παρα "para," "near, against, contrary to" + μνήμη "mnēmē," "memory") or '''promnesia''', is the experience of feeling sure that one has witnessed or experienced a new situation previously (an individual feels as though an event has already happened or has happened in the near past), although the exact circumstances of the previous encounter are uncertain. The term was coined by a [[France|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," or "weirdness." The "previous" experience is most frequently attributed to a dream, although in some cases there is a firm sense that the experience "genuinely happened" in the past.
'''Déjà vu''' ({{pron-en|ˈdeɪʒɑː ˈvuː|en-uk-dejavu.ogg}}; {{IPA-fr|deʒa vy|lang|fr-déjà vu.ogg}}, "already seen"; also called '''[[Reduplicative paramnesia|paramnesia]],''' from Greek παρα "para," "near, against, contrary to" + μνήμη "mnēmē," "memory") or '''promnesia''', is the experience of feeling sure that one has witnessed or experienced a new situation previously (an individual feels as though an event has already happened or has happened in the near past), although the exact circumstances of the previous encounter are uncertain. The term was coined by a [[France|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", or "weirdness". The "previous" experience is most frequently attributed to a dream, although in some cases there is a firm sense that the experience "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 also found in literature of the past,[1] 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. Recently, researchers have found ways to recreate this sensation using hypnosis.[2]
The experience of déjà vu seems to be quite common among adults and children alike. References to the experience of déjà vu are also found in literature of the past,<ref>{{cite web | title = Neppe Déjà Vu Research and Theory | work = Pacific Neuropsychiatric Institute | url = http://www.rebornspirit.com/23.html | accessdate = 2005-11-29 }}</ref> 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. Recently{{when?}}, researchers have found ways to recreate this sensation using hypnosis.<ref name="Brown2004">{{cite book | last = Brown | first = Alan S. | title = The Déjà Vu Experience | publisher = Psychology Press | year = 2004 | isbn = 1841690759 |url= http://books.google.com/books?id=5flMtjmezeYC&vq=the+deja+vu+experience+alan+brown&source=gbs_navlinks_s}}</ref>


==Scientific research==
==Scientific research==


Since the last years of the [[20th century]], déjà vu has been subject to serious psychological and neurophysiological research. Scientifically speaking, the most likely explanation 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 impression that an experience is "being recalled."
Since the last years of the [[20th century]], déjà vu has been subject to serious psychological and neurophysiological research. Scientifically speaking, the most likely explanation 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 impression that an experience is "being recalled".


This explanation is substantiated 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. Likewise, as time passes, subjects{{where}} 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]] (events which are perceived as being in the present) 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.
This explanation is substantiated 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. Likewise, as time passes, subjects{{where}} 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]] (events which are perceived as being in the present) 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.


Another theory being explored is that of vision. As the theory suggests, one eye may record what is seen fractionally faster than the other, creating that "strong recollection" sensation upon the "same" scene being viewed milliseconds later by the opposite eye.<ref> [http://mb-soft.com/public/dejavu.html A Theory on the Deja Vu or Déjà vu Phenomenon]</ref> However, this one fails to explain the phenomenon when other sensory inputs are involved, such as the auditive part, and especially the digital part. If one, for instance, experiences déjà vu of someone slapping the fingers on his left hand, then the déjà vu feeling is certainly not due to his right hand experiencing the same sensation later than his left hand considering that his right hand would never receive the same sensory input. Also, persons with only one eye still report experiencing déjà vu or déjà vécu (a rare disorder of memory, similar to persistent déjà vu). The global phenomenon must therefore be narrowed down to the brain itself (say, one hemisphere would be late compared to the other one).
Another theory being explored is that of vision. As the theory suggests, one eye may record what is seen fractionally faster than the other, creating that "strong recollection" sensation upon the "same" scene being viewed milliseconds later by the opposite eye.<ref>[http://mb-soft.com/public/dejavu.html A Theory on the Deja Vu or Déjà vu Phenomenon]</ref> However, this one fails to explain the phenomenon when other sensory inputs are involved, such as the auditive part, and especially the digital part. If one, for instance, experiences déjà vu of someone slapping the fingers on his left hand, then the déjà vu feeling is certainly not due to his right hand experiencing the same sensation later than his left hand considering that his right hand would never receive the same sensory input. Also, persons with only one eye still report experiencing déjà vu or déjà vécu (a rare disorder of memory, similar to persistent déjà vu). The global phenomenon must therefore be narrowed down to the brain itself (say, one hemisphere would be late compared to the other one).


===Links with disorders===
===Links with disorders===
Early researchers tried to establish a link between déjà vu and serious psychopathology such as [[schizophrenia]], [[anxiety]], and [[dissociative identity disorder]], with hopes of finding the experience of some diagnostic value. However, there does not seem to be any special association between déjà vu and [[schizophrenia]] or other psychiatric conditions.<ref>[http://books.google.com/books?id=5flMtjmezeYC&dq=the+deja+vu+experience+alan+brown&pg=PP1&ots=ugU8LkXHOA&sig=-MPgMH6oJTkN4kchoJMKzVgcBwk&hl=en&prev=http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2003-49,GGLD:en&q=the+deja+vu+experience+alan+brown&sa=X&oi=print&ct=title&cad=one-book-with-thumbnail The Déjà Vu Experience, by Alan S. Brown]</ref> The strongest pathological association of déjà vu is with [[temporal lobe epilepsy]].<ref> [http://www.neurologychannel.com/seizures/types.shtml Neurology Channel]</ref><ref name = "pnoegm">[http://people.howstuffworks.com/question657.htm Howstuffworks "What is déjà vu?]</ref> This correlation has led some researchers to speculate that the experience of déjà vu is possibly a [[neurology|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. the sudden "jolt," a [[hypnic jerk|hypnagogic jerk]], that frequently 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.
Early researchers tried to establish a link between déjà vu and serious psychopathology such as [[schizophrenia]], [[anxiety]], and [[dissociative identity disorder]], with hopes of finding the experience of some diagnostic value. However, there does not seem to be any special association between déjà vu and [[schizophrenia]] or other psychiatric conditions.<ref name="Brown2004"/> The strongest pathological association of déjà vu is with [[temporal lobe epilepsy]].<ref> [http://www.neurologychannel.com/seizures/types.shtml Neurology Channel]</ref><ref name = "pnoegm">[http://people.howstuffworks.com/question657.htm Howstuffworks "What is déjà vu?]</ref> This correlation has led some researchers to speculate that the experience of déjà vu is possibly a [[neurology|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. the sudden "jolt", a [[hypnic jerk|hypnagogic jerk]], that frequently 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===
===Pharmacology===
It has been reported that 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 on 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. Many scientists are still working towards the actual link of déjà vu with hypnagogic epilepsy.
It has been reported that 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 on 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. Many scientists{{which?}} are still working towards the actual link of déjà vu with hypnagogic epilepsy.


===Memory-based explanations===
===Memory-based explanations===
The similarity between a déjà-vu-eliciting stimulus and an existing, but different, memory trace may lead to the sensation (Brown, 2004; Cleary, 2008). 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 (2008) 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 "cryptamnesia," which is where information learned is forgotten but nevertheless stored in the brain, and occurrence of similar invokes the contained knowledge, leading to a feeling of familiarity because of the situation, event or emotional/vocal content, known as "déjà vu."
The similarity between a déjà-vu-eliciting stimulus and an existing, but different, memory trace may lead to the sensation.<ref name="Brown2004"/><ref name="Cleary2008">{{cite journal | author = Cleary, Anne M. |title = Recognition memory, familiarity and deja vu experiences | journal = Current Directions in Psychological Science | year = 2008 | volume = 17 | pages = 353–357 | doi = 10.1111/j.1467-8721.2008.00605.x}}</ref> 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<ref name="Cleary2008"/> 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 "cryptamnesia", which is where information learned is forgotten but nevertheless stored in the brain, and occurrence of similar invokes the contained knowledge, leading to a feeling of familiarity because of the situation, event or emotional/vocal content, known as "déjà vu".


==Alternative explanations==
==Alternative explanations==
===Mystic explanation===
===Mystic explanation===
Déjà vu is associated with [[precognition]], [[clairvoyance]] or [[extra-sensory perception]]s, and it is frequently cited as evidence for "[[parapsychology|psychic]]" abilities in the general population. Non-scientific explanations attribute the experience to [[prophecy]], visions (such as received in dreams), or past-life memories. Some believe that déjà vu is a glimpse of a life that could have been, for example when you make a choice in life it takes you down a certain path, when you are on that path you have a glimpse of your life, having made a different choice.
Déjà vu is associated with [[precognition]], [[clairvoyance]], or [[extra-sensory perception]]s, and it is frequently cited{{by whom?}} as evidence for "[[parapsychology|psychic]]" abilities in the general population. Non-scientific explanations attribute the experience to [[prophecy]], visions (such as received in dreams), or past-life memories. Some{{who?}} believe that déjà vu is a glimpse of a life that could have been, for example when you make a choice in life it takes you down a certain path, when you are on that path you have a glimpse of your life, having made a different choice.


===Dreams===
===Dreams===
Some believe déjà vu is the memory of [[dreams]]. Though the majority of dreams are never remembered, a dreaming person can display activity in the areas of the brain that process long-term memory. It has been speculated that dreams read directly into long-term memory, bypassing short-term memory entirely. In this case, déjà vu might be a memory of a forgotten dream with elements in common with the current waking experience. This may be similar to another phenomenon known as déjà rêvé, or "already dreamed." However, later studies on mice indicate that long-term memories must be first established as short-term memories.
Some{{who?}} believe déjà vu is the memory of [[dreams]]. Though the majority of dreams are never remembered, a dreaming person can display activity in the areas of the brain that process long-term memory. It has been speculated{{by whom?}} that dreams read directly into long-term memory, bypassing short-term memory entirely. In this case, déjà vu might be a memory of a forgotten dream with elements in common with the current waking experience. This may be similar to another phenomenon known as déjà rêvé, or "already dreamed". However, later studies{{which?}} on mice indicate that long-term memories must be first established as short-term memories.


===Reincarnation===
===Reincarnation===
Those believing in [[reincarnation]] theorize that déjà vu is caused by fragments of past-life memories being jarred to the surface of the mind by familiar surroundings or people. Others theorize that the phenomenon is caused by [[astral projection]], or [[out-of-body experience]]s (OBEs), where it is possible that individuals have visited places while in their [[astral body|astral bodies]] during sleep. The sensation may also be interpreted as connected to the fulfillment of a condition as seen or felt in a [[premonition]].
Those believing{{which?}} in [[reincarnation]] theorize that déjà vu is caused by fragments of past-life memories being jarred to the surface of the mind by familiar surroundings or people. Others theorize{{who?}} that the phenomenon is caused by [[astral projection]], or [[out-of-body experience]]s (OBEs), where it is possible that individuals have visited places while in their [[astral body|astral bodies]] during sleep. The sensation may also be interpreted as connected to the fulfillment of a condition as seen or felt in a [[premonition]].


==Related phenomena==
==Related phenomena==
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Jamais vu is sometimes associated with certain types of [[amnesia]] and [[epilepsy]].
Jamais vu is sometimes associated with certain types of [[amnesia]] and [[epilepsy]].


Theoretically, as seen below, a jamais vu feeling in a sufferer of a [[delirium|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/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 [[irreality]]) feelings.
Theoretically, as seen below, a jamais vu feeling in a sufferer of a [[delirium|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/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 [[irreality]]) feelings.


Times Online reports:
Times Online reports:
{{cquote|[[Chris Moulin]], of the [[University of Leeds]], asked 92 volunteers to write out "door" 30 times in 60 seconds. At the [[International Conference on Memory]] in [[Sydney]] last [[week]] he reported that 68 per cent 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.<ref>[http://www.timesonline.co.uk/article/0,,6-2282789,00.html Doctor, I've got this little lump on my arm . . . Relax, that tells me everything | Anjana Ahuja - Times Online<!-- Bot generated title -->]</ref>}}'''
{{cquote|[[Chris Moulin]], of the [[University of Leeds]], asked 92 volunteers to write out "door" 30 times in 60 seconds. At the [[International Conference on Memory]] in [[Sydney]] last [[week]] he reported that 68 per cent 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.<ref>{{cite web |url=http://www.timesonline.co.uk/article/0,,6-2282789,00.html |title=Doctor, I've got this little lump on my arm . . . Relax, that tells me everything |first=Anjana |last=Ahuja |publisher=Times Online}}</ref>}}'''


===Tip of Tongue (Presque vu)===
===Tip of Tongue (Presque vu)===
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Déjà vu is similar to, but distinct from, the phenomenon called [[tip of the tongue]] which is when one cannot recall a familiar word or name or situation, 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.
Déjà vu is similar to, but distinct from, the phenomenon called [[tip of the tongue]] which is when one cannot recall a familiar word or name or situation, 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 (feeling)|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 their tongue."
Presque vu (from French, meaning "almost seen") is the sensation of being on the brink of an [[epiphany (feeling)|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 their tongue".


Presque vu is often cited by people who suffer from [[epilepsy]] or other seizure-related brain conditions, such as [[temporal lobe lability]].
Presque vu is often cited by people who suffer from [[epilepsy]] or other seizure-related brain conditions, such as [[temporal lobe lability]].
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{{reflist}}
{{reflist}}
===Further reading===

{{refbegin}}
* {{cite web | title = Neppe Déjà Vu Research and Theory | work = Pacific Neuropsychiatric Institute | url = http://www.rebornspirit.com/23.html | dateformat = mdy | accessdate = November 29 2005 }}
* {{cite book | last = Brown | first = Alan S. | title = The Déjà Vu Experience | publisher = Psychology Press | year = 2004 | isbn = 1841690759}}
* {{cite book | last = Draaisma | first = Douwe | title = Why life speeds up as you get older | publisher = Cambridge University Press | year = 2004 | isbn = 0521691990}}
* {{cite book | last = Draaisma | first = Douwe | title = Why life speeds up as you get older | publisher = Cambridge University Press | year = 2004 | isbn = 0521691990}}
* {{cite journal | author = J. H. Jackson | authorlink = J. Hughlinks-Jackson | title = A particular variety of epilepsy "intellectual aura", one case with symptoms of organic brain disease | journal = Brain | year = 1888 | volume = 11 | pages = 179–207 | url = http://brain.oxfordjournals.org/cgi/reprint/11/2/179 | doi = 10.1093/brain/11.2.179',}}
* {{cite journal | first = J. |last = Hughlinks-Jackson | title = A particular variety of epilepsy "intellectual aura", one case with symptoms of organic brain disease | journal = Brain | year = 1888 | volume = 11 | pages = 179–207 | url = http://brain.oxfordjournals.org/cgi/reprint/11/2/179 | doi = 10.1093/brain/11.2.179}}
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* {{cite news |url=http://www.nytimes.com/2004/09/14/science/14deja.html?ex=1252900800&en=331d6db9dff26282&ei=5090&partner=rssuserland |title=Déjà Vu: If It All Seems Familiar, There May Be a Reason |publisher=New York Times |date=2004-09-14}}
{{refend}}
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* {{cite news |url=http://www.nytimes.com/2006/07/02/magazine/02dejavu.html |title=Déjà Vu, Again and Again |publisher=New York Times |date=2006-07-02}}
* {{cite journal | author = Cleary, Anne M. |title = Recognition memory, familiarity and deja vu experiences | journal = Current Directions in Psychological Science | year = 2008 | volume = 17 | pages = 353–357 | doi = 10.1111/j.1467-8721.2008.00605.x}}
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* {{cite news |url=http://www.canada.com/ottawacitizen/news/story.html?id=2c4f7afd-5a3a-4e52-a2fb-bc729692bfb4&k=48785 |title=When déjà vu is more than just an odd feeling |publisher=The Ottawa Citizen |date=2006-02-20}}
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* {{cite web |url=http://serendip.brynmawr.edu/bb/neuro/neuro98/202s98-paper2/Johnson2.html |title=UGH! I Just Got the Creepiest Feeling That I Have Been Here Before: Déjà vu and the Brain, Consciousness and Self |publisher=Neurobiology and Behavior |year=1998}}
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* {{cite web |url=http://chronicle.com/free/v50/i46/46a01201.htm |title=The Tease of Memory |publisher=The Chronicle of Higher Education |date=2004-07-23}}
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* {{cite web |url=http://www.sciencedaily.com/releases/2008/11/081118122146.htm |title=The Psychology Of Deja Vu |publisher=Science Daily |date=2008-11-19}}
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* {{cite web |url=http://www.psychologicalscience.org/onlyhuman/2008/10/and-i-feel-like-ive-been-here-before.cfm |title=And I feel like I've been here before |first=Wray |last=Herbert |publisher=Psychological Science |date=2008-10-23}}
* {{cite journal | author = McHugh TJ, Jones MW, Quinn JJ, ''et al.'' | title = Dentate gyrus NMDA receptors mediate rapid pattern separation in the hippocampal network | journal = Science | volume = 317 | issue = 5834 | pages = 94–9 | year = 2007 | month = July | pmid = 17556551 | doi = 10.1126/science.1140263 | url = }}


==External links==
==External links==
* [http://www.cbc.ca/quirks/media/2005-2006/mp3/qq-2006-02-25d.mp3 Chronic déjà vu - quirks and quarks episode (mp3)]
* [http://www.cbc.ca/quirks/media/2005-2006/mp3/qq-2006-02-25d.mp3 Chronic déjà vu - quirks and quarks episode] (mp3)
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* [http://www.anthonypeake.com A new theory that links déjà vu to Near-Death Experience] &mdash; by Anthony Peake, 2006.
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* [http://www.canada.com/ottawacitizen/news/story.html?id=2c4f7afd-5a3a-4e52-a2fb-bc729692bfb4&k=48785 "When déjà vu is more than just an odd feeling" ''The Ottawa Citizen'', February 20 2006]
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* [http://chronicle.com/free/v50/i46/46a01201.htm "The Tease of Memory" ''The Chronicle of Higher Education'', July 23 2004]
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* [http://www.nytimes.com/2004/09/14/science/14deja.html?ex=1252900800&en=331d6db9dff26282&ei=5090&partner=rssuserland "Déjà Vu: If It All Seems Familiar, There May Be a Reason" ''New York Times'', September 14, 2004]
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*[http://www.nytimes.com/2006/07/02/magazine/02dejavu.html "Déjà Vu, Again and Again" ''New York Times'', July 2, 2006]
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* [http://serendip.brynmawr.edu/bb/neuro/neuro98/202s98-paper2/Johnson2.html "UGH! I Just Got the Creepiest Feeling That I Have Been Here Before: Déjà vu and the Brain, Consciousness and Self", Neurobiology and Behavior, 1998]
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* [http://www.anthonypeake.com A new theory that links déjà vu to Near-Death Experience. Anthony Peake 2006]
* [http://skepdic.com/dejavu.html The Skeptic's Dictionary]
* [http://skepdic.com/dejavu.html The Skeptic's Dictionary]
* [http://science.howstuffworks.com/deja-vu.htm How Déjà Vu Works a Howstuffworks article]
* [http://science.howstuffworks.com/deja-vu.htm How Déjà Vu Works] &mdash; a Howstuffworks article
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* [http://www.deja-experience-research.org Déjà Experience Research] &mdash; a website dedicated to providing déjà experience information and research
*[http://www.sciencemag.org/cgi/content/abstract/1140263 Dentate Gyrus NMDA Receptors Mediate Rapid Pattern Separation in the Hippocampal Network]
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* [http://www.psychologicalscience.org/onlyhuman/2008/10/and-i-feel-like-ive-been-here-before.cfm And I feel like I've been here before]
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* [http://www.sciencedaily.com/releases/2008/11/081118122146.htm Science Daily Article, November 19, 2008]
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* [http://www.deja-experience-research.org A website dedicated to providing déjà experience information and research]


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{{DEFAULTSORT:Deja Vu}}

Revision as of 23:51, 17 August 2009

Déjà vu (Template:Pron-en; Template:IPA-fr, "already seen"; also called paramnesia, from Greek παρα "para," "near, against, contrary to" + μνήμη "mnēmē," "memory") or promnesia, is the experience of feeling sure that one has witnessed or experienced a new situation previously (an individual feels as though an event has already happened or has happened in the near past), although the exact circumstances of the previous encounter are uncertain. 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", or "weirdness". The "previous" experience is most frequently attributed to a dream, although in some cases there is a firm sense that the experience "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 also found in literature of the past,[1] 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. Recently[when?], researchers have found ways to recreate this sensation using hypnosis.[2]

Scientific research

Since the last years of the 20th century, déjà vu has been subject to serious psychological and neurophysiological research. Scientifically speaking, the most likely explanation 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 impression that an experience is "being recalled".

This explanation is substantiated 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. Likewise, as time passes, subjects[where?] 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 (events which are perceived as being in the present) 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.

Another theory being explored is that of vision. As the theory suggests, one eye may record what is seen fractionally faster than the other, creating that "strong recollection" sensation upon the "same" scene being viewed milliseconds later by the opposite eye.[3] However, this one fails to explain the phenomenon when other sensory inputs are involved, such as the auditive part, and especially the digital part. If one, for instance, experiences déjà vu of someone slapping the fingers on his left hand, then the déjà vu feeling is certainly not due to his right hand experiencing the same sensation later than his left hand considering that his right hand would never receive the same sensory input. Also, persons with only one eye still report experiencing déjà vu or déjà vécu (a rare disorder of memory, similar to persistent déjà vu). The global phenomenon must therefore be narrowed down to the brain itself (say, one hemisphere would be late compared to the other one).

Early researchers tried to establish a link between déjà vu and serious psychopathology such as schizophrenia, anxiety, and dissociative identity disorder, with hopes of finding the experience of some diagnostic value. However, there does not seem to be any special association between déjà vu and schizophrenia or other psychiatric conditions.[2] The strongest pathological association of déjà vu is with temporal lobe epilepsy.[4][5] 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. the sudden "jolt", a hypnagogic jerk, that frequently 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

It has been reported that 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 on 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. Many scientists[which?] are still working towards the actual link of déjà vu with hypnagogic epilepsy.

Memory-based explanations

The similarity between a déjà-vu-eliciting stimulus and an existing, but different, memory trace may lead to the sensation.[2][6] 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[6] 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 "cryptamnesia", which is where information learned is forgotten but nevertheless stored in the brain, and occurrence of similar invokes the contained knowledge, leading to a feeling of familiarity because of the situation, event or emotional/vocal content, known as "déjà vu".

Alternative explanations

Mystic explanation

Déjà vu is associated with precognition, clairvoyance, or extra-sensory perceptions, and it is frequently cited[by whom?] as evidence for "psychic" abilities in the general population. Non-scientific explanations attribute the experience to prophecy, visions (such as received in dreams), or past-life memories. Some[who?] believe that déjà vu is a glimpse of a life that could have been, for example when you make a choice in life it takes you down a certain path, when you are on that path you have a glimpse of your life, having made a different choice.

Dreams

Some[who?] believe déjà vu is the memory of dreams. Though the majority of dreams are never remembered, a dreaming person can display activity in the areas of the brain that process long-term memory. It has been speculated[by whom?] that dreams read directly into long-term memory, bypassing short-term memory entirely. In this case, déjà vu might be a memory of a forgotten dream with elements in common with the current waking experience. This may be similar to another phenomenon known as déjà rêvé, or "already dreamed". However, later studies[which?] on mice indicate that long-term memories must be first established as short-term memories.

Reincarnation

Those believing[which?] in reincarnation theorize that déjà vu is caused by fragments of past-life memories being jarred to the surface of the mind by familiar surroundings or people. Others theorize[who?] that the phenomenon is caused by astral projection, or out-of-body experiences (OBEs), where it is possible that individuals have visited places while in their astral bodies during sleep. The sensation may also be interpreted as connected to the fulfillment of a condition as seen or felt in a premonition.

Jamais vu

Jamais vu is a term in psychology (from French, meaning "never seen") 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 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/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 irreality) feelings.

Times Online reports:

Chris Moulin, of the University of Leeds, asked 92 volunteers to write out "door" 30 times in 60 seconds. At the International Conference on Memory in Sydney last week he reported that 68 per cent 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.[7]

Tip of Tongue (Presque vu)

Déjà vu is similar to, but distinct from, the phenomenon called tip of the tongue which is when one cannot recall a familiar word or name or situation, 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 their tongue".

Presque vu is often cited by people who suffer from epilepsy or other seizure-related brain conditions, such as temporal lobe lability.

L'esprit de l'escalier

L'esprit de l'escalier (from French, "staircase wit") is remembering something when it is too late (for example, a clever comeback to a remark, thought of after the conversation has ended).

An example of L'esprit de l'escalier in popular culture can be seen in "The Comeback", the 147th episode of the TV sitcom Seinfeld. It is also discussed in the film You've Got Mail.

See also

References

  1. ^ "Neppe Déjà Vu Research and Theory". Pacific Neuropsychiatric Institute. Retrieved 2005-11-29.
  2. ^ a b c Brown, Alan S. (2004). The Déjà Vu Experience. Psychology Press. ISBN 1841690759.
  3. ^ A Theory on the Deja Vu or Déjà vu Phenomenon
  4. ^ Neurology Channel
  5. ^ Howstuffworks "What is déjà vu?
  6. ^ a b Cleary, Anne M. (2008). "Recognition memory, familiarity and deja vu experiences". Current Directions in Psychological Science. 17: 353–357. doi:10.1111/j.1467-8721.2008.00605.x.
  7. ^ Ahuja, Anjana. "Doctor, I've got this little lump on my arm . . . Relax, that tells me everything". Times Online.

Further reading