Scientific Explanation of Déjà vu

Imagine this: you're going about your day, all appears normal, when suddenly you're hit with a wave of certainty that you've lived this moment before. The following moments feel incredibly familiar, almost as if you've predicted them. While you've no doubt heard of deja vu, the unsettling theories behind this phenomenon could surprise you, unless of course you've heard them before. (eerie music) Deja vu is a French term meaning already seen. The term describes an eerie and sometimes uncanny sensation of already having lived an experience you find yourself in, or the feeling that an experience is incredibly familiar but not knowing why it feels that way, because it shouldn't.

Because of its random and sudden nature, it's difficult to recreate in a lab setting; therefore, it's unclear how many people experience deka vu. By some estimates, at least 30% of people have experienced Deja vu, though other estimates suggest that the range could be higher, from 60 to 80%. Many people who experience Deja vu do so for the first time at a young age, with many first-time cases reported to occur between the ages of 6 and 10; however, the most common time to have Deja vu experiences is in early adulthood between the ages of 15 and 25. After the age of 25, people generally report less and less instances of Deja vu.

Many people believe that this is an indication of an increasingly functional mind, as people over the age of 25 are better at discerning what is real and no longer associate unrelated experiences with their memories. Because Deja vu is so unexpected and fleeting, many associate the feeling as something mysterious, spiritual, or even paranormal. Some believe that experiencing Deja vu is a sign of recalling experiences or memories from a past life. This is a widely held spiritually-leaning belief about the sensation, as it makes someone feel like they've already been somewhere or experienced something before. Other spiritual explanations consider Deja vu as an indication that an individual is on their right path in life.

In an alternative theory, YouTuber and energy worker Diana Magic theorizes in one video that Deja vu occurs when the higher self, a term sometimes used to describe one's inner guidance that is separate from one's personality or ego, becomes conscious of the self on Earth experiencing life. In what is probably the most famous use of Deja vu in pop culture, the 1999 film "The Matrix" follows a protagonist computer hacker learning that the world is merely a computer simulation, the work of an elaborate cyber intelligence. During one scene, the protagonist Neo sees a black cat perfectly replicating behavioral twitches twice down a hallway, and refers to it as Deja vu.

In a larger plot line of the film, it is later explained as, quote, "a glitch in the matrix," something revealing the programmed reality had been altered. While it may be either a hint that our spirit is watching out for us, or perhaps a malfunction of our simulated reality, some theories are a bit more rooted in science. Some researchers believe that cases of Deja vu may be related to how memories are made and stored in the brain, which largely occurs in the temporal lobes, where long-term memories, experiences, and facts are stored. In support of this theory, scientists point out that one of the groups of people who most commonly and frequently report experiences of Deja vu are people who have epilepsy, the most common form of which is called temporal lobe epilepsy.

In cases of temporal lobe epilepsy, the seizures start in the temporal lobe. Studies also indicate that some patients who have temporal lobe epilepsy report experiencing Deja vu just before an epileptic event or seizure, with such frequency that it can function as sort of a warning sign. But of course, not everyone who experiences Deja vu also experiences epilepsy, though abnormal electrical impulses that contribute to epilepsy can occur in people that don't have it. Thus, some have posited that Deja vu is sort of a, quote, "short in the circuits of our brain," which can take many forms, such as neurons pertaining to recognition and familiarity firing mistakenly, making the brain mistake the present for the past, or neurons pertaining to short-term memory accidentally going across circuits for long-term memory, skipping over the short-term memory bank completely.

Similarly, the, quote, "mismatch in neural pathways" in the case of non-epileptic peoples may have to do with the multitude of ways that the brain creates the entire perception of a single memory, which includes all sensory information. As there are many different pathways for the brain to process sensory information to store memories, it's possible that a small amount of sensory information, like a curious smell, could trigger the feeling of familiarity that can't be placed with the exact memory with which it should be associated. The theory of delayed processing suggests that when you observe something, the information relayed to your brain by your senses runs along two very separate pathways.

 If one of these pathways is processed more rapidly than the other, even if it doesn't seem like a huge difference in timing, the brain might break the single event into two different experiences, and we cannot recall the memory as a whole entity. There is also a camp of researchers that believe that when it comes to perceiving familiarity in cases of Deja vu, it might have to do with the sensation of making sense of the feeling, rather than the issue with the feeling itself. One study used MRI imaging to do brain scans on participants experiencing a lab-induced simulation of Deja vu.

 They found that the areas of the brain most triggered were related to decision-making rather than to memory. In this theory, the feeling of Deja vu would be the result of the brain doing a very quick form of conflict resolution, trying to ascertain if there is a conflict between what we think we've experienced in the experiences and what has occurred. The multitude of theories both paranormal and scientific all speak to just how little we know about Deja vu, and whether it is just neural pathways misfiring, or the mistakes of artificially intelligent overlords. When it happens, it's definitely unsettling and incredibly curious.