On gradients and texture "gradients."

Comments on J. E. Cutting and R. T. Millard's article (see record 1985-08483-001) on the extent to which texture gradients, systematic variations in image texture due to perspective projection of surface texture, provide information about the shape and disposition of surfaces relative to a viewer. The present author suggests that it is difficult to conclude that the perception of flatness or curvature derives from processes that capitalize on these gradient relationships, per se. The difficulty becomes most apparent when attempting to formalize the perceptual computations and the spatial information that is made explicit. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)