It hits you out of nowhere, gets you thinking hard and leaves you utterly confused. Deja vu! You never understand what’s going on when deja vu happens. And it leaves you thinking - “I wonder why we deja vu.”
Well, here’s why.
Deja vu is as confusing for science to explain as it’s for you to feel. Since it’s not something that can be seen in brain scans, there’s no full proven explanation for it. But there are a few theories.
This first theory is related to how we recall our memories.
Our brain constantly checks our senses to look for things we find familiar. When it recognises something as familiar, a part of the brain recalls the memory associated with it.
What we see, what we smell, what we hear are all recorded at the same time to form one event.
So this theory says, if our brain receives these senses out of order - for example, if something sounds familiar, but we don’t receive the smell and sight of it at the same time, our brain won’t recall that memory.
That is deja vu. It’ll be seen as a different event but it’ll still feel familiar.
But this doesn’t explain why it happens for completely new situations. That’s where this theory fails and the second one comes in.
Everything we go through in our day-to-day lives is stored in our brain as memories.
Experiences are first stored in the short-term memory and then later sent to the long-term memory.
But in a deja vu - there’s a little detour. In this, an experience accidentally skips past the short-term memory and directly goes to the long-term memory.
This makes us feel like a new event is being recalled from the past. Yep, deja vu.
But hang on, there’s one last theory.
A region of the brain (rhinal cortex) detects familiarity and another one (hippocampus) recalls memories.
Normally, they’re good friends and go hand in hand. The confusion begins when one of them goes rogue.
So when the familiarity centre gets activated on its own, without switching on the recall memory button, deja vu happens.
All of these theories have one thing in common. They all point to deja vu being a glitch in how our brain works.
So why do we deja vu? That’s still a mystery, but these theories try to answer how it all goes down. Which theory do you find most convincing?
Direction and Graphics: Kunal Mehra
Video Editor: Ashish Maccune
Cameraperson: Athar Rather, Abhay Sharma and Abhishek Ranjan
Camera Assistant: James Kannanthara
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