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 ...

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 ...

Hold a pencil upright in front of your face. Close one eye, look at the pencil, then open that eye, and close the other. Did you notice that your view of the pencil shifted slightly when you looked ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. Credit: Nastynice1 via Reddit A supposedly 3D optical illusion has been posted online and is ...