Two lines touch the top and bottom of both black dots.
Bigger or smaller?
Delboeuf illusion
Which black dot is bigger?
They are the same size, though the one in the tight ring looks bigger.
Why? A ring that hugs the dot makes it look larger, and a lot of empty space around it makes it look smaller. It’s why the same meal can look bigger on a smaller plate.
Picture: Washiucho, Public domain · Wikipedia(opens in a new tab)