Why do we experience déjà vu and how does it happen?

We experience déjà vu when our brain thinks it has seen something before, even though it hasn’t, like remembering a toy you just saw for the first time.

Imagine you’re playing with your favorite building blocks. You stack them up and look at them. Then, later, you see someone else stacking blocks in almost the same way, and suddenly you think, “I’ve seen this before!” That’s déjà vu, it feels like a memory from earlier.

Our brain has two parts that help us remember things: one that notices what is happening right now, and another that checks if something feels familiar. Sometimes these two parts get confused, the “familiar” part says “I know this!” even though the “noticing” part just saw it for the first time.

It’s like when you hear a song that sounds familiar, but you can’t place where you’ve heard it before. Your brain is trying to match something new with an old memory, and sometimes it gets mixed up!

So, déjà vu is your brain having a little mix-up between what it sees now and what it remembers from earlier. It’s like when you think you’ve seen the same toy twice, but you just saw it once!