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The Science of Depth Perception and the Reverse Perspective Illusion

Reverse perspective is of interest because of the light it sheds on normal perception.

From everyday visual experience, all human beings learn that distant objects generally appear smaller than near objects, and that shading reveals which parts of an object are protrusions and which parts are recessions. Moreover, from early childhood we soon come to understand that as we move around a physical object, we will be able to see more of the object's other surfaces and less of the surface initially facing toward us.

The reverse perspective illusion adds a real third dimension to the artwork itself while manipulating perspective and shading information in ways that are contrary to the actual 3-D structure. In brief, the receding parts of the 3-D artwork are drawn larger to make them appear near, while the protruding parts of the sculpture are drawn smaller to make them appear far. The illusion of reverse perspective becomes interesting when we move in front of the scene.

Suddenly, the third dimension becomes important, because as we move the changing angle on the 3-D structure provides us with visual information that is contrary to what we expect on the basis of the perspective and shading information. The viewer cannot reconcile what they are seeing with what they thought they would see. The mind then conjures up a whole three dimensional scene that is in fact not there. This is the essence of the reverse perspective illusion.