Science World: Exhibits: Optical Illusions: Two Faces or a Vase?

Vase Or Faces?

In this illusion there are two faces and a vase. Most people tend to see the two faces first, because when we process black on white information, the black information gets processsed first. This is probably because we have become accustomed to reading ink (usually black or a dark colour) on paper (usually white or a light colour). If you scroll down you will see the same image, with the colours inverted. You should see the vase first in this case.

The reason you cannot see both faces and the vase at exactly the same time is because our brain processes more visual information at the centre of our visual field rather than at the periphery. Therefore, when you look at the picture you can only recognize one of the two images at any given moment.