The Hollow Face Illusion is probably one of the most amazing optical illusions we have come across. The mask can be stood up in a window and the whole face seems to follow you as you move around the room. Truly, an amazing illusion...

Grand Illusions has commissioned this particular version of the Hollow Face Illusion, featuring Albert Einstein. It is made from a very strong plastic (opal styrene) and is virtually unbreakable.

Richard Dawkins mentions this illusion in his recent book 'The God Delusion.'

How does it work? Well, when we 'see' something, our view of the world has been processed by our brain. And our brain 'knows' that a face is convex, not concave, so that is the way we see it. When we move, the face does not move in the way that a convex face would move, so our brain comes up with a different explanation, and we see the face move, following us wherever we go!

The mask is 43cm high and 31cm wide.

The BBC television programme QI, hosted by Stephen Fry, recently featured the Einstein Mask. Watch the video.