A tricky optical illusion challenges viewers to find a margarita glass without a lime. The puzzle tests observation skills ...

As one of the abstract styles developing in the 1960s, Optical illusion (or Op) Art features games of lines and geometric shapes in both black and white—like in the case of Bridget Riley, Jesús Rafael ...

If you think spotting a snail hiding among these rocks is just a game, think again. You are going to put your neural ...