Have you ever felt this strange feeling of having already experienced a situation when it is simply impossible? Almost everyone has experienced this at one time or another. Psychologists at Colorado State University in the United States may have just provided an answer to this very curious phenomenon.
What is déjà vu ?
We can define the feeling of “deja-vu” as the impression of having already experienced a present situation with a vague feeling of unreality and strangeness. Although this feeling is very vivid, we are unable to remember when we experienced it or why it feels so familiar. this experience usually lasts no more than a few seconds. The expression “sensation of deja vu” was first used in 1876 by Emile Boirac (1851-1917) who used it in his book entitled L’Avenir des sciences psychiques.
What causes déjà vu to happen ?
The causes of this sensation have always interested scientists who are trying to find an interpretation for it. From the 19th century, many theories began to emerge in an attempt to provide an explanation. We will present to you some of the theories on deja vu that seem most likely:
Between short and long term memory
All the studies that have been made today, agree on the same point is that this phenomenon is due to a psychic anomaly and not to a paranormal experience. What confirms this thesis is that deja vu is rather frequent in patients who suffer from epilepsy, which links it to excessive activity in the temporal lobe of the brain, where memory and sensory perception are located.
One of the predominant theses is that there is an overlap between short-term memory and long-term memory, that is to say, that we store as long-term memory something that we have just perceived, which causes that for a few moments we have the feeling that this situation belongs to the past when we have just experienced it for the first time.
Between the conscious and the unconscious
Nevertheless, the most accepted theory within the scientific community is the one that we are going to explain to you in the rest of this article, This theory states that the feeling of having experienced something before is due to a delay in the optical path. Our eye perceives an image, but between the thousandths of a second that this organ takes to send this stimulus to the brain, our unconscious has already stored the image and when our brain analyzes it, we are unable to remember the origin of this memory, which causes this feeling of already lived.
To illustrate this explanation, you could be told that it is a bit like visiting a city that you have already seen in a film, by visiting it, the latter would seem familiar to you but you would not be able to remember why.
The feeling of “déjà-vu” deciphered by science
A few years ago, Alan Brown, professor and researcher at Southern Methodist University in Dallas in the United States, tried to see a little more clearly about this curious phenomenon of “déjà-vu”. After having ruled out anything resembling the paranormal and analyzing many studies on the subject, including many testimonials from people, he was able to establish some fundamental conclusions on this phenomenon.
Contrary to what one might think, he was able to determine that not everyone has had this kind of experience in their life. According to him, two out of three people have one day had this feeling of “deja-vu”. He also noticed that in the majority of cases, the first triggers are a scene or a given place and the second trigger is a conversation. Finally, he also established a link between this sensation and certain types of epileptic seizures.
Alan Brown’s work has been useful to other scientists who have studied the feeling of “déjà-vu” in people with epilepsy. During an epileptic seizure, the passage of nerve impulses is disturbed. This dysfunction, which manifests itself as a kind of short circuit, spreads throughout the brain and in particular in the medial temporal lobes, generating a feeling of “deja vu”. It is a region close to the hippocampus called the rhinal cortex that is responsible for this sensation in people who have epileptic seizures.
Psychologists at Colorado State University have investigated an old hypothesis based on Gestalt’s Law of Familiarity. According to this law, the sensation of “deja-vu” can take place when there is a spatial resemblance between a current scene and a scene “engraved” in memory, but which we do not necessarily remember, Still according to the Gestalt hypothesis, the fact of being confronted with a scene which resembles another encountered in the past will not necessarily materialize by a memory, but rather by a strong feeling of familiarity.
To study this idea in the laboratory, the scientists subjected participants to scenes generated by virtual reality techniques. They used this technology to immerse people in scenes created from scratch. Some of them had the same spatial arrangements while 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 the participants were in a virtual scene with the same spatial layout as an earlier scene they had seen, but had no memory of it.
These results are interesting, but they do not mean that spatial resemblance is the only triggering factor for this feeling of “déjà-vu”. Many other factors must most likely be involved. Further research will therefore be necessary to deepen knowledge of this very curious phenomenon.