Figure 1

The upper panel shows a number of cues that may contribute to recognition of a given object. Although 3D cues are not available in this stimulus, the color, texture, shading, internal contours, and boundary contours all allow the monkey to be identified. The silhouette in the middle panel provides only the boundary contours, but this is still adequate for recognition. The bottom panel has replaced the boundary contours with an array of dots. This stimulus is sufficient for recognition with substantial reliability even when the dots are displayed for only a brief moment. It is possible that identification of the shape does not depend on registering collinearity of the dots that are serving as contour markers.