And yes, it does work with other faces besides Einstein.
Stephen Fry, on the BBC TV quiz show "QI", shows participants a rotating Einstein mask optical illusion, an example of a hollow face illusion, where "your eye tells you it's poking outwards, and yet, it isn't."
Your brain so wants to see a face curving outwards that it ignores other information and refuses to let you see that the face is actually curving inwards.
(Watch till the end of the video for a bonus illusion which makes the queen of England happy or sad using a five pound note.)
Optical Illusion with an Einstein Mask on QI
- Buy Einstein Hollow Face Mask at Grand Illusions>>
- BBC2 QI>>
- Hollow-Face Illusion, Wikipedia>>