Most people have experienced Deja vu at some point in their lives, that eerie feeling that something in their life has repeated. Perhaps it is an image, or a conversation, or a book that causes that feeling that this has been experienced before, even if you can’t remember when exactly. And often, people struggling to explain the experience cannot remember a similar incident that would lead to such a feeling of recognition and familiarity.
Over the years, some paranormal explanations have been introduced for this feeling. Some have suggested that Deja vu is caused by forgotten dreams or a body of collective human experience. Similarly, some turn to reincarnation as an explanation, and postulate that the buried memories of forgotten lifetimes lead to that feeling of familiarity. Some even suggest that it may be due to out of body experiences, in which something is seen but not consciously remembered.
More scientific inquiries have yielded no less varying theories. Though the term “Deja vu,” French for “already seen,” was coined in 1896, people had been experiencing it long before then. Nathaniel Hawthorne described the feeling well in the mid-1800s as a feeling that “somewhere or other I had seen just this strange spectacle before.” But though the feeling can be easily described, and was easily named, explanations for it have not been so simple.
In the late 1800s, common theories for Deja vu included fatigue – as well as being over-rested. The psychologist who proposed the latter suggested that being over-rested led to being able to perceive things more quickly than usual, leading to a feeling of familiarity when the rest of the brain catches up. Other psychologists suggested that Deja vu was caused by one hemisphere of the brain perceiving something a moment before the other hemisphere, or the subconscious perceiving something before the conscious mind could register it. Carl Jung proposed the “collective consciousness” theory, in which he suggested that there exists a communal body of human experience which we experience subconsciously. But there was no proof to support these theories, any of which could sound plausible.
Research into the phenomenon is ongoing and has an extensive history. In the early 20th century psychologist Edward B Titchener posited that Deja vu was caused by someone getting a momentary glimpse of something before full conscious perception of it occurs. This results in a false familiarity of the event once the brain has completed its construction of the experience. While this hasn’t been strictly tested, there is a commonly accepted explanation that the phenomenon of Deja vu is neither the product of precognition nor prophecy. It is an anomalous memory event that gives the falsely represents being recalled.
The strongest evidence against Deja vu being an actual recollection lies in the observation that in most circumstances, no matter how strongly the current feeling is that the situation has been repeated, the details of the first event are uncertain. As the idea of it being a premonition or exact replica situation has been refuted, several theories have come up on how the brain generates Deja vu situations. Some discuss the possibility that it is an overlap between short-term and long-term memory neurological systems. The result is that the events from the recent past seem to have occurred much longer ago.
Some researchers have tried to associate the experience of Deja vu with psychopathology. Studies were done to try to form a link between Deja vu and the likes of schizophrenia, anxiety, and identity disorders. To date, however, there has been no significant evidence to suggest that they are linked. Others preferred attempting to link the occurrence with temporal lobe epileptic episodes. It is the strongest pathological associate of Deja vu, which has led to the speculation that Deja vu is a neurological anomaly related to electrical discharge in the brain. The same electrical discharge that is responsible for the epileptic episodes may be the source of the neurological event that leads to the erroneous sensation of memory. More research into this link is being completed.
While there are no specific psychological links to Deja vu, there are pharmaceutical links. Under the influence of the drugs amantadine and phenylpropanolamine combined, there is record of more intense and recurrent sensations of Deja vu. The man who experienced the events was so interested that he completed his treatment and reported his experience to psychologists for them to complete a case study. The theory that developed from this study was that Deja vu is a product of hyperdopaminergic action in certain areas of the brain. The research will have to be repeated before this explanation is officially accepted.
Another common explanation comes from a less scientific basis. The idea is that Deja vu is a result of very similar but not identical situations. This occurs in familiar settings or with familiar company. In this case, an actual memory is so close to the current event that, due to the nature of memories, makes it difficult to tell that the events are unique. Basing the idea of Deja vu on memories may be one method to test for a reproducible event. This would allow researchers to pinpoint the neurological and physical sensations responsible for phenomenon. Familiarity based Deja vu is being tested with the use of virtual reality equipment. Scenarios are created that match with a known memory, but differ slightly. The results of this testing seems promising, as there seems to be a correlation that shows the spatial layout of the new experience aids in the perception of Deja vu. This leads to the closest form of testing that is currently available into the Deja vu experience.
There is also another term that is similar to Deja vu: jamais vu (meaning “never seen”). In almost a complete opposite effect, jamais vu is the occurrence of being in a familiar place, but not recognizing it. Unlike Deja vu, there are several known sources that cause this. Intoxication, a delirious disorder, and other delusions could be the source of the complication.
Deja vu is certainly an interesting phenomenon to think of. Scientists are working diligently to try to explain what causes it and to try to see if there are certain factors that are responsible for its occurrence. Whatever the cause may be, people will certainly be intrigued by it for a long time.