The sensation of “déjà-vu”: towards a scientific explanation

There is nothing paranormal about the feeling of “déjà-vu”

We can define the feeling of “déjà-vu” as the impression of experiencing a current situation with a vague sense of unreality and strangeness. The term “déjà vu” was first used in 1876 by Emile Boirac (1851-1917) who used it in his book entitled The future of the psychic sciences.

The causes of this sensation have always interested scientists who are trying to find an interpretation for it. By the 19th century, many theories began to emerge in an attempt to provide an explanation. The first of these also gave way to paranormal pride by trying to explain that this feeling of “déjà-vu” was for some a memory of a past life and for others a premonition. Finally, for others, this impression of experiencing a situation would be associated with a telepathic reception with the astral body separated from the physical body, a bit like a scout!

For some researchers, this feeling of “déjà-vu” comes from a mental malfunction. Therefore, the origin would be neurological and related to transmission disorders between the two hemispheres of the brain, which would then enter into a kind of desynchronization. Other explanations have been presented and explain this phenomenon with the occurrence of electric discharges at the level of neurons or with the interruption of the transmission of nerve impulses.

Other more psychological explanations are sometimes put forward in an attempt to shed light on this phenomenon. Emotion and attention can be triggers.

>> To also read: Why do bad memories remain etched in our memories?

The feeling of “déjà-vu” deciphered by science

The feeling of deja vu is a common symptom in epileptics. Source: Ralwell/Shutterstock

A few years ago, Alan Brown, professor and researcher at Southern Methodist University in Dallas in the United States, tried to see this curious phenomenon of “déjà-vu” a little more clearly. After ruling out anything paranormal and analyzing many studies on the subject, including many testimonies from people, he was able to draw some basic conclusions about this phenomenon.

Contrary to what one might think, he was able to determine that not everyone has had this type of experience in their life. According to him, two out of three people have had this feeling of “déjà-vu” one day. He also observed that in most cases, the first trigger is a certain scene or place and the second trigger is a conversation. Finally, he also established a connection between this sensation and certain types of epileptic seizures.

Alan Brown’s work has been helpful to other scientists who have studied the feeling of deja vu in people with epilepsy. During an epileptic crisis, the passage of nerve impulses is disturbed. This dysfunction, which manifests itself as a kind of short circuit, spreads throughout the brain and especially in the middle temporal lobes, generating a feeling of “already seen”. It is a region near the hippocampus called the cortex that is responsible for this sensation in people who have epileptic seizures.

>> To also read: Epilepsy: what exactly happens during a seizure?)

The Gestalt Familiarity Hypothesis

Psychologists at Colorado State University have investigated an old hypothesis that relies on Gestalt’s Law of Familiarity. According to this law, the sensation of “déjà-vu” can occur when there is a spatial similarity between an actual scene and a scene “etched” into memory, but not necessarily remembered.

Always according the Gestalt hypothesisthe fact of encountering a scene that resembles another scene encountered in the past will not necessarily be materialized by a memory, but by a strong sense of familiarity.

To study this idea in the laboratory, scientists subjected participants to scenes created by virtual reality techniques. They used this technology to immerse people in scenes created from scratch. Some of them had the same spatial arrangements, being different in the choice of decor.

The results were not long in coming. As expected, the feeling of “déjà vu” occurred almost every time participants were in a virtual scene with the same spatial arrangement as a previous scene they had seen but did not remember.

These results are interesting, but it does not mean that spatial similarity is the only factor that causes this feeling of “déjà-vu”. Most likely many other factors must be involved. Therefore, further research will be needed to deepen the knowledge about this very curious phenomenon.

(Also read: Is deja vu a figment of the mind?)

Source:

Anne Cleary, Professor of Cognitive Psychology, “What is deja vu? Psychologists are exploring this chilling feeling of having experienced an experience before.” Conversationpublished: October 3, 2022, https://theconversation.com/what-is-deja-vu-psychologists-are-exploring-this-creepy-feeling-of-having-already-lived-through-an-experience-fore-187746

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