Optical illusions are older than you think. The first optical illusions date back to 20,000 BC and took the form of cave sculptings. Nowadays they are found all over the place – on screens, in books ...

Optical illusions play tricks on your brain and can make you see things that aren't really there, from static images swirling around the page to images that stay with you even after you look away.

An optical illusion is a visual phenomenon where the brain perceives an image differently from how it physically exists. These illusions occur due to the way our eyes and brain process light, colour, ...