An event that already happened or an illusion of consciousness? The truth behind déjà vu

You are sitting in a place you have never been, having a conversation you have never had, and suddenly it happens: a strong and strange feeling takes hold of you — "I have been here before." "I have already heard this sentence." "I know this moment." But when you try to remember when it happened, you have no answer. You know the moment is new, yet the brain sends you a completely opposite feeling. So why does this happen and what is actually going on in the brain during these seconds?

The feeling of déjà vu, which means "already seen" in French, is a sense of familiarity with a new situation, as if we have already experienced it in the past. It is a very common phenomenon that can occur in completely healthy people and usually lasts a few seconds. The confusing part is that the feeling can be very convincing: for a moment we really feel that we have already experienced this situation in the past, even though we know we have no clear memory of the previous time.

The brain does not have time to process information

According to studies, one of the central hypotheses is that déjà vu is created when there is a mismatch between the way the brain processes new information and its memory mechanisms. At any given moment, the brain absorbs many details and tries to simultaneously compare them to information already stored within it. When a feeling of familiarity is created without a clear memory being retrieved to explain it, we may interpret the feeling as something we have already experienced.

Another possibility is that the brain processes the same information twice, with a fraction of a second difference. The first time we may not even notice what we have absorbed, and when the brain processes the same information again, it may cause us to feel that we have already seen or experienced it before.

Some people experience it more than others

Although every person can experience déjà vu, studies have found some characteristics that recur in people who report the phenomenon more frequently. Among other things, links were found to a relatively young age, a higher level of education, frequent travel, and a better ability to remember dreams. Déjà vu is reported frequently, especially among young people, with the ages of 15–25 considered a period when the phenomenon is more common.

Ultimately, déjà vu is perhaps one of the most fascinating examples of the fact that our brain does not just remember reality — it also interprets it in real time. The feeling that we "have been here before" can be strong and convincing, even when the moment never occurred. And precisely because of this gap between what we feel and what we know, déjà vu continues to be one of the most intriguing phenomena in the study of memory and consciousness.