Look at these two upside-down pictures of Mona Lisa. Then look further below at both Monas right-side-up.
You probably recognized Mona Lisa right away--even upside-down. Two upside-down Monas may look strange (one perhaps stranger than the other), but turn them right-side-up and one looks normal, the other grotesque. Why the surprising difference?
Since an upside-down face is not a familiar point of view, you may not have noticed that one of these pictures has been altered. In the right-hand photo, Mona's eyes and mouth have been turned around. It's only when the photos are turned right-side-up, and the view is more familiar, that you notice the real distortion.
Since you are obviously using a computer to view this, you may have access to photo-processing software and image-capture hardware. Try to capture your own face and flip the eyes and mouth.
Apologies to Leonardo da Vinci for the desecration of his masterpiece.
©1994,1995,1996The Exploratorium