paramnesia n : (psychiatry) a disorder of memory in which dreams or fantasies are confused with reality

Déjà vu (pronounced ; French "already seen"; also called paramnesia , from Greek παρα para, "near" + μνήμη mnēmē, "memory") 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 repeated itself). 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 very common among adults and children alike; in formal studies 70% of people report having experienced it at least once. References to the experience of déjà vu are also found in literature of the past, 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.

Types of déjà vu

According to Arthur Funkhouser there are three major types of déjà vu.

Déjà vécu

Déjà vécu refers to an experience involving more than just sight, which is why labeling such "déjà vu" is usually inaccurate. The sense involves a great amount of detail, sensing that everything is just as it was before and a weird knowledge of what is going to be said or happen next.

Translated literally as 'already lived,' déjà vécu is described in a quotation from Charles Dickens: When most people speak of déjà vu, they are actually experiencing déjà vécu. Surveys have revealed that as much as 70% of the population have had these experiences, usually between ages 15 to 25, when the mind is still subject to noticing the change in environment. The experience is usually related to a very ordinary event, but it is so striking that it is remembered for several years afterwards.

More recently, the term déjà vécu has been used to describe very intense and persistent feelings of a déjà vu type, which occur as part of a memory disorder.

Déjà senti

This phenomenon specifies something 'already felt.' Unlike the implied precognition of déjà vécu, déjà senti is primarily or even exclusively a mental happening, has no precognitive aspects, and rarely if ever remains in the afflicted person's memory afterwards.

Dr. John Hughlings Jackson recorded the words of one of his patients who suffered from temporal lobe or psychomotor epilepsy in an 1888 paper:

As with Dr. Jackson's patient, some temporal-lobe epileptics may experience this phenomenon.

Déjà visité

This experience is less common and involves an uncanny knowledge of a new place. The translation is "already visited." Here one may know his or her way around in a new town or landscape while at the same time knowing that this should not be possible.

Dreams, reincarnation and also out-of-body travel have been invoked to explain this phenomenon. Additionally, some suggest that reading a detailed account of a place can result in this feeling when the locale is later visited. Two famous examples of such a situation were described by Nathaniel Hawthorne in his book Our Old Home and Sir Walter Scott in Guy Mannering. Hawthorne recognized the ruins of a castle in England and later was able to trace the sensation to a piece written about the castle by Alexander Pope nearly a century earlier.

C. G. Jung published an account of déjà visité in his 1952 paper On synchronicity.

In order to distinguish déjà visité from déjà vécu, it is important to identify the source of the feeling. Déjà vécu is in reference to the temporal occurrences and processes, while déjà visité has more to do with geography and spatial relations.

Scientific research

In recent years, déjà vu has been subjected 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; it is 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 can exhibit a strong recollection of having the "unsettling" experience of déjà vu itself, but little to 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). In other words, the events would be stored into memory before the conscious part of the brain even receives the information and processes it. This would explain why one is, if it ever comes to mind, powerless trying to twist the outcome of the event in order to create a paradox. The delay is only of a few milliseconds, and besides, already happened at the time the conscious of the individual is experiencing 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. 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/her left hand, then the déjà vu feeling is certainly not due to his/her right hand to be late on the left one. Also, persons with only one eye still report experiencing déjà vu or déjà vecu. 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

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 neurotic conditions. However, the strongest pathological association of déjà vu is with temporal lobe epilepsy. and "Behold how the thing which thou hast seen in thy dream is, after a considerable lapse of time, fully realized."

Some people have suggested that a feeling of remembering occurs in a sense that a person might realize that what he had dreamt is now a relevant present action that is taking place right here right now.

"I was once sitting down in the kitchen noticing that my plate seemed well too familiar, it seemed as if my head motions were foreseen, and that every move would trigger a continuation to happen or so, I had many déjà vu's as a child but this was extraordinary, I knew from the bottom of my heart that I had dreamed this situation years ago, as a little boy, that amazingly an entire piece of memory was regained and I finally understood when and where I was dreaming and how long this dream was, and most importantly how many years ago did I dream."

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 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. For further cases of remembering information from past lives, see Ian Stevenson.

Related phenomena

Jamais vu

main Jamais vu Jamais vu is a term in psychology (from the 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:

Tip of Tongue (Presque vu)

Full article at tip of the tongue

Déjà vu is similar to, but distinct from, the phenomenon called tip of the tongue which is when you cannot recall a familiar word or name or situation, but with effort you eventually recall 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

Full article at 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 come-back to a remark, thought of after the conversation has ended. Another common example: when you are about to take a test and are able to recall everything, but, as soon as the test begins, you forget all that you've learned; after taking the test you remember absolutely everything that you had forgotten while taking it.

An example of L'esprit de l'escalier in popular culture can be seen in the TV sitcom Seinfeld. In one episode, the character George Costanza thinks of a perfect comeback-line to an insult he received from a co-worker, but too late to deliver it. While George is rapidly consuming a bowl of shrimp during an office meeting, a co-worker teases him, saying "Hey George, the ocean called. It's running out of shrimp". Only later in the day does George conceive of the perfect comeback: "Well, the jerk store called. They're running out of you."

See also

• Anamnesis
• Phenomenon
• Precognition
• Psychology

References

• The Déjà Vu Experience
• Why life speeds up as you get older

External links

• Chronic deja vu- quirks and quarks episode (mp3)
• "When deja vu is more than just an odd feeling" The Ottawa Citizen, February 20 2006
• "The Tease of Memory" The Chronicle of Higher Education, July 23 2004
• "Déjà Vu: If It All Seems Familiar, There May Be a Reason" New York Times, September 14, 2004
• "Déjà Vu, Again and Again" New York Times, July 2, 2006
• "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
• A new theory that links deja vu to Near-Death Experience. Anthony Peake 2006
• The Skeptic's Dictionary
• How Déjà Vu Works a Howstuffworks article
• Dentate Gyrus NMDA Receptors Mediate Rapid Pattern Separation in the Hippocampal Network