Déjà vu

Déjà vu (/ˌdeɪʒɑː ˈv(j)uː/ ⓘ[1][2] DAY-zhah-VOO, -⁠VEW, French: [deʒa vy] ⓘ; "already seen") is the phenomenon of feeling as though one has lived through the present situation before.

[3][4][5][6] It is an illusion of memory whereby—despite a strong sense of recollection—the time, place, and context of the "previous" experience are uncertain or impossible.

[9][10] The phenomenon manifests occasionally as a symptom of seizure auras, and some researchers have associated chronic/frequent "pathological" déjà vu with neurological or psychiatric illness.

This evidence, found by Émile Boirac, helps the public understand what déjà vu can entail on the average brain.

"Our brain recognizes the similarities between our current experience and one in the past ... left with a feeling of familiarity that we can't quite place.

Taiminen and Jääskeläinen (2001)[26] explored the case of an otherwise healthy person who started experiencing intense and recurrent sensations of déjà vu upon taking the drugs amantadine and phenylpropanolamine together to relieve flu symptoms.

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.

In an effort to reproduce the sensation experimentally, Banister and Zangwill (1941)[32][33] 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".

Familiarity-based recognition refers to the feeling of familiarity with the current situation without being able to identify any specific memory or previous event that could be associated with the sensation.

After completing the puzzle, each participant in the PHA group received a posthypnotic amnesia suggestion to forget the game in the hypnosis.

[36] More participants in PHF group felt a strong sense of familiarity, for instance, comments like "I think I have done this several years ago."

Some participants in PHA group related the familiarity when completing the puzzle with an exact event that happened before, which is more likely to be a phenomenon of source amnesia.

In contrast, participants in the PHF group reported that they felt confused about the strong familiarity of this puzzle, with the feeling of playing it just sliding across their minds.

The induced "deja vu" state was created by getting them to look at a series of logically related and unrelated words.

[38] 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 the event or experience being experienced has already been experienced in the past, known as "déjà vu".

The proposed sense of recognition (déjà vu) involves achieving a good match between the present experience and the stored data.

Efron proposed that if the two signals were occasionally not synchronized properly, then they would be processed as two separate experiences, with the second seeming to be a re-living of the first.

Research done by Zuger (1966) supported this idea by investigating the relationship between remembered dreams and déjà vu experiences, and suggested that there is a strong correlation.

[42] Some researchers, including Swiss scientist Arthur Funkhouser, firmly believe that precognitive dreams are the source of many déjà vu experiences.

If we can access shared knowledge déjà vu could potentially be an effect of recognizing one of the collectively stored patterns.

Sixty-eight percent of the subjects reported symptoms of jamais vu, with some beginning to doubt that "door" was a real word.