Have you ever walked on a lane you have never visited before but you still feel a sense of familiarity? Or whether you have finished a conversation with someone contemplating about how you have exchanged the same exact words but cannot recollect when? Well, you are clearly experiencing a Déjà vu.
This French word refers to something as already seen and is a mental sensation of experiencing intense familiarity along with full knowledge that this familiarity is mistaken.
Dr Akira O’Connor, a senior psychology lecturer at the University of St Andrews, explains, “Déjà vu is basically a conflict between the sensation of familiarity and the awareness that the familiarity is incorrect. And it’s the awareness that you’re being tricked that makes déjà vu so unique compared to other memory events.”
“Most healthy people don’t tend to believe the sensation of familiarity and change their behavior – like Neo in The Matrix, they logically know something isn’t right,” he further adds.
One theory explains that this happens when you see something two different times due to split perception. This implies that when you experience an event for the first time it lacked your full attention and hence after it entered your perception it was felt like two different events. However, in reality, it was the continued perception of the same event.
Healthline explains, “The first time you see something, you might take it in out of the corner of your eye or while distracted. Your brain can begin forming a memory of what you see even with the limited amount of information you get from a brief, incomplete glance. So, you might actually take in more than you realize.”
According to some experts, a certain kind of brain malfunction might cause this sesnsation. They state that when your brain contains information, it follows a specific route from short-term memory storage to long-term memory storage. However, this theory says that in certain situations the information might not follow the original path and can take a shorter route to long-term memory storage. Thus, you may perceive it as reliving a long-ago memory rather than something that occurred a while ago. Another theory offers an explanation of delayed processing. The information transmitted in your brain adopts two separate routes and one of the routes processes the information a little faster than the other. The delay might be extremely insignificant but with passing time your brain interprets the same event as two ferent experiences.
James Giordano Ph.D. a professor of neurology at Georgetown University Medical Center explains how déjà vu. occurs as things might come out of sync from your brain. "Networks of the temporal lobe and frontal cortex 'interpret' this mismatch and we experience this as a memory playing out in real-time, which makes it seem as if we're 're-experiencing' something that is actually new," says Giordano.
A study in Frontiers in Psychology in 2013 further discovered that déjà vu stems from a memory conflict in the brain, where the brain tries to distinguish what is real memory and what is not.
Leigh Winters talks about how déjà vu might be a consequence of your brain sensinf familiarity. " You may also be more familiar with the situation that sparks déjà vu than you think. "It might be possible that déjà vu occurs when you detect familiarity, stimulating the rhinal cortices, but don’t activate the hippocampus, which helps you recall more concrete memory details," says Winters.
"Some propose that this is why déjà vu has that eerie feeling of semi-remembering, or feeling like you’ve been there before but can’t seem to put your finger on it." Because, let's be honest, who hasn't felt a sense of eeriness when it comes to déjà vu? "Because déjà vu often occurs suddenly — with no warning — and is fleeting in duration, it’s incredibly hard to study in a clinical setting in a healthy population," adds Winters.
It has been witnessed that most experiences of déjà vu occur between the age periods of 15 and 25. Hence, although about 60 to 70% of people report having déjà vu, the occurrence of this phenomenon is more common and likely to happen with younger people. This phenomenon is also associated with stress and is reported that the higher the degree of stress, the higher the probability of déjà vu.
It is true that déjà vu is another marvel of the human brain, and is a testament that a tiny mismatch or glitch can make you relive an entire moment. Giordano mentions, “Déjà vu is actually a good sign, and seems to reflect the brain's ability to process memories at different levels and at differing speeds."