Science explains that weird déjà vu feeling

Ever had that eerie feeling you’ve lived a moment before—like reality is on a strange loop? That’s déjà vu, French for “already seen.” And it’s not just a quirky brain glitch; it’s actually a fascinating clash between a false sense of familiarity and what you know to be true. Surprisingly common, as studies show about two-thirds of people have experienced it at least once, scientists have been trying to crack its mystery for years, and for good reason.

Beyond ordinary memory

This insight shows how déjà vu is more complex than regular memory recall; it’s a rare mental glitch where your brain’s recognition system gets tangled, making the experience both puzzling and fascinating.

When perception plays tricks

In déjà vu, certain delusions arise from perception being fooled by illusions. These mental tricks create a misleading sense of familiarity, blurring the line between what’s real and what our mind imagines.

More questions than answers

So, if déjà vu isn’t a simple memory mistake, what causes it? For more than a century, experts have proposed various theories trying to explain this puzzling feeling.

Dopamine’s role

Dopamine, a neurotransmitter tied to pleasure and motivation, also plays a key role in déjà vu. It helps create that odd feeling when something feels both familiar and new, blending reward and recognition in the brain.

How age shapes déjà vu experiences

Age affects how often we experience déjà vu, and young people tend to have it more often. This may be due to stronger neural activity and sharper “fact-checking” in the frontal brain regions of younger minds.

The brain’s role in déjà vu

O’Connor explains that understanding what happens during déjà vu requires knowing how the brain is organized and how its different parts communicate to create that familiar-yet-strange feeling.

“Then there’s another brain region—the frontal cortex, located at the forehead—that handles higher thinking like reasoning, decision-making, and fact-checking. It plays a big role in how we process experiences like déjà vu,” says O’Connor.

When the brain overreacts

The brain then becomes overexcited, signaling that you’ve experienced a place or event before. This flood of activity creates the conscious feeling of familiarity that defines déjà vu.

Completing the déjà vu cycle

And when the fact-checking in the frontal cortex confirms the experience simply isn’t possible, it signals that the sensation was a mistake, completing the déjà vu cycle and leaving you with that weird feeling.

The truth about déjà vu

“People often worry about déjà vu, thinking it’s a memory glitch,” says O’Connor. “But in most cases, it’s actually a sign that your brain and mind are working well and keeping your memory systems in check.”

Jamais vu explained simply

Ever stared at a familiar word and suddenly questioned its spelling? Or walked into a well-known room and felt like it was brand new? That’s jamais vu: a common brain glitch where the familiar suddenly feels strange.

The strange effect of repeating words

Unlike déjà vu, jamais vu can be triggered quite easily. In their study, O’Connor and his team asked participants to repeatedly read or write the same word, leading many to feel the word suddenly looked strange or unfamiliar.

Why jamais vu feels so weird

“It makes sense,” says O’Connor, “because feeling unfamiliar with something super common like everyday words feels especially strange. That contrast makes the jamais vu effect even more noticeable.”