Optical illusions occur naturally in different habitats and conditions across the world. Cloud formations can sometimes make it seem like there's an ocean or a UFO in the sky. Whether it is salt flats ...

Hidden number and letter optical illusions are some of the most satisfying puzzles because they look unbelievably simple until you actually try them. In this challenge, you are shown a neat grid ...

A couple of years ago an optical illusion came along and almost broke our site. Over three million people read an article about the most dizzying illusion ever to grace our screens – the rotating ...

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 ...

Chances are you’ve encountered some version of the “Ebbinghaus illusion,” in which a central circle appears to be smaller when encircled by larger circles and seems larger when surrounded by smaller ...

The famous Ebbinghaus illusion, named for its discoverer, the German psychologist Hermann Ebbinghaus (1850–1909). Despite appearances, the two orange circles are the same size. Have you ever looked at ...