Checker shadow illusion

Okay, so you know how when you look at a checkerboard, some squares are black and some are white, right?

Now imagine you put a bunch of objects on top of that checkerboard, like a toy car or a teddy bear. When you shine a light on those objects, they will cast a shadow onto the checkerboard.

So let's say you take a picture of that checkerboard with the objects and shadows on it, and you look at the picture. You might think that some of the squares in the shadow are darker than the squares that aren't in the shadow, right? But, here's the trick:

If you actually measured the brightness of each square with a tool, like a light meter, you would find out that all the squares are actually the same brightness!

It's like magic! Or an illusion, really. This is called the checker shadow illusion, and it happens because our brains are really good at making assumptions and shortcuts about what we see.

When we see a checkerboard with objects and shadows on it, our brain automatically assumes that the squares that are in the shadow are darker than the squares that aren't in the shadow. It's just the way our brains work.

But, when we measure the brightness of each square with a tool, we realize that our brain was tricking us, and that all the squares are actually the same brightness.

So, even though it looks like some of the squares are darker than others, they're not! It's just an illusion. Cool, huh?