At first glance, this photo looks like a simple patterned rug with a pair of shoes tossed casually on the floor. But look closer - there’s a sneaky object hiding in plain sight. A photo posted 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 ...