What causes déjà vu, and why does it feel so uncanny?

You get déjà vu when your brain thinks it’s seeing something new, but actually remembers it from before, like when you walk into a room and think you’ve been there hundreds of times.

Imagine you have a favorite picture book. You see a page with a funny cat wearing sunglasses. One day, you look at that same page without remembering you’d seen it before, but your brain says, “Wait! I know this!” That’s déjà vu, like when your brain gives you a surprise reminder.

Think of your brain as a detective who sometimes gets confused. When you see something familiar, the detective tries to match it with old memories, but sometimes he mixes up the clues. That mix-up makes your brain feel like it’s getting a secret message from the past: “Hey! I’ve seen this before!”

It feels so uncanny because your brain is trying to tell you a story, and you’re listening, even if you don’t know why.