Optical illusion with woman's hidden face can only be seen by

We love a good optical illusion and this one is up there, but it may make you feel a tad dizzy if you look for too long.

Optical Illusion Challenge: Only a Genius can find the Sad Woman

Three visual illusions that reveal the hidden workings of the brain - The University of Sydney

A Century-Old Optical Illusion: Can you Spot an Old Woman & a

What Is An Optical Illusion?, Blog

The Brain's Face Recognition System Is Easy to Fool

Solving donkey brainteaser in six seconds means you have

Seek And Find Puzzles : Can You Find The Face Of 2nd Woman

How many faces do you see? Optical illusion leaves viewers baffled

50 Optical Illusions That Will Blow Your Mind - Parade