Here’s How Déjà Vu Works

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Have you ever had that strange sensation that you’ve been somewhere or met someone before. This strange yet ubiquitous phenomenon is known as déjà vu. But what exactly is it and why do we get it?


DÉJÀ VU is french for “already seen”. Which makes sense since a deja vu episode consists of a feeling of already having seen or experienced something before. And these episodes can last anywhere between 10 to 30 seconds.

What actually causes it is still a mystery, but there are a few theories, and they typically fall under two main categories: Associative and Biological.

The associative category is comprised of theories that suggest that environmental stimuli like sounds or smells are triggering déjà vu experiences. And biological theories point to a structural or chemical abnormality in the brain as the déjà vu trigger.


One such theory has to do with brain development, since young people experience déjà vu the most, and it tapers off with age. Other research links déjà vu to temporal lobe epilepsy.

Epilepsy is a condition that causes brain cells to send out-of-control electrical signals that affect the cells around them.

These haywire signals create a domino effect amongst the brain’s cells and results in a seizure. Which is when a person loses control of their thoughts and body movements. But what does that have to do with déjà vu exactly?


Well, temporal lobe epilepsy in particular starts in the temporal lobe. Which is the area of your brain just on top of your ears and is responsible for making and remembering memories. People who have temporal lobe epilepsy frequently report having déjà vu just before they have a seizure.

Which means that, for people who do NOT have temporal lobe epilepsy, déjà vu could just be a mini seizure that stops before it grows too large. What’s likely happening is, the familiar feeling you get is signalled by cells in the temporal lobe.

But gets ignored by other parts of the brain that check to make sure whether the signals make sense. A simpler biological theory is called Dual Processing Theory, in which the brain processes new stimuli twice, and the second time mistakes it as something it’s already familiar with.


Scientists can’t explain exactly why this mistake occurs, but it’s one of the more widely accepted déjà vu theories.

There’s also an associative theory called Divided Attention Theory, which suggests that the experience giving you déjà vu is actually something you’ve experienced before. Only you weren’t paying enough attention at the time to make a full memory of it.

Pretty cool stuff huh?

Unfortunately, it’s really difficult to test déjà vu theories as personal reports of it are varied. Which continues to make it an extremely fascinating topic of study.

What’s your déjà vu theory?