ABSTRACT
Any single object can project an infinity of image configurations to the retina. The orientation of the object to tbe viewer can vary continuously, each giving rise to a different two-dimensional projection. The object can be occluded by other objects or texture iields, as when viewed behind foliage. The object need not be presented as a full-colored textured image but instead can be a simplifi.ed line drawing. Moreover, the object can even be missing some of its parts or be a novel exemplar of its particular category. But it is only with rare exceptions that an image fails to be rapidly and readily classified, either as an instance of a familiar ol!iect category or as an instance that cannot be so classified (itself a form of classification).
