Déjà vu

Déjà vu (/ˌdeɪʒɑː ˈvuː, - ˈvjuː/ (listen) is the feeling that one has lived through the present situation before. The phrase translates literally as 'already seen'. Although some interpret déjà vu in a paranormal context, mainstream scientific approaches reject the explanation of déjà vu as 'precognition' or 'prophecy'. Rather, they explain it as an anomaly of memory, since despite the strong sense of recollection, the time, place, and practical context of the 'previous' experience are uncertain or believed to be impossible. Two types of déjà vu are recognized: the pathological déjà vu usually associated with epilepsy or that which, when unusually prolonged or frequent, or associated with other symptoms such as hallucinations, may be an indicator of neurological or psychiatric illness, and the non-pathological type characteristic of healthy people, about two-thirds of whom have had déjà vu experiences. People who travel more or watch more movies are more likely to experience déjà vu than others. Furthermore, people also tend to experience déjà vu more in fragile conditions or under high pressure, and research shows that the experience of déjà vu also decreases with age. Déjà vu (/ˌdeɪʒɑː ˈvuː, - ˈvjuː/ (listen) is the feeling that one has lived through the present situation before. The phrase translates literally as 'already seen'. Although some interpret déjà vu in a paranormal context, mainstream scientific approaches reject the explanation of déjà vu as 'precognition' or 'prophecy'. Rather, they explain it as an anomaly of memory, since despite the strong sense of recollection, the time, place, and practical context of the 'previous' experience are uncertain or believed to be impossible. Two types of déjà vu are recognized: the pathological déjà vu usually associated with epilepsy or that which, when unusually prolonged or frequent, or associated with other symptoms such as hallucinations, may be an indicator of neurological or psychiatric illness, and the non-pathological type characteristic of healthy people, about two-thirds of whom have had déjà vu experiences. People who travel more or watch more movies are more likely to experience déjà vu than others. Furthermore, people also tend to experience déjà vu more in fragile conditions or under high pressure, and research shows that the experience of déjà vu also decreases with age. Déjà vu is most strongly associated with temporal lobe epilepsy. This experience is a neurological anomaly related to epileptic electrical discharge in the brain, creating a strong sensation that an event or experience currently being experienced has already been experienced in the past. Early researchers tried to establish a link between déjà vu and mental disorders such as anxiety, dissociative identity disorder and schizophrenia but failed to find correlations of any diagnostic value. No special association has been found between déjà vu and schizophrenia. A 2008 study found that déjà vu experiences are unlikely to be pathological dissociative experiences. Some research has 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, along with jamais vu, occurs often enough during seizures (such as simple partial seizures) that researchers have reason to suspect a link. Certain drugs increase the chances of déjà vu occurring in the user, resulting in a strong sensation that an event or experience currently being experienced has already been experienced in the past. 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. Because of 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. Déjà vu may happen if a person experienced the current sensory twice successively. The first input experience is brief, degraded, occluded, or distracted. Immediately followed by that, the second perception might be familiar because the person naturally related it to the first input. One possibility behind this mechanism is that the first input experience involves shallow processing, which means that only some superficial physical attributes are extracted from the stimulus. Implicit memory Research has associated déjà vu experiences with good memory functions. Recognition memory enables people to realize the event or activity that they are experiencing has happened before. When people experiencing déjà vu, they would have the recognition memory triggered by certain situations which they have never encountered. The similarity between a déjà-vu-eliciting stimulus and an existing, or non-existing but different, memory trace may lead to the sensation that an event or experience currently being experienced has already been experienced in the past. Thus, encountering something that evokes the implicit associations of an experience or sensation that cannot be remembered may lead to déjà vu. In an effort to reproduce the sensation experimentally, 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 3 of the 10 participants reporting what the authors termed 'paramnesias'.