Optical illusions that hide words and objects in plain sight are great for testing your visual acuity, attention to detail, ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. Credit: Gaetano Kanizsa Optical illusions come in all forms, from the cognitive to the ...

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 ...