(or "About Face") provides a startling example of
the major role of memory and past experience in perception.
Two photographs of a womans face (Vanna White) are mounted
on a turntable which is fixed to a wall. The turntables are
weighted so that the photos are normally seen upside down,
and they appear normal. However, when the visitor flips the
pictures right side up, one photo looks grotesquely strange:
the eyes and mouth in the photo have been cut out and inverted.
The alteration of the photo is painfully obvious when viewed
right side up, but much less noticeable when upside down.
This is because eyes and mouth are the two areas where we
focus our attention most strongly when we look at faces.