Endogenously-Supplied Visual Attributes of Depth

Abstract

Two-dimensional objects misperceived to be three-dimensional, have a smaller “near” face and its elements are sharper and narrower than those of the “far” face. In addition, the object acquires a number of attributes of “real” depth—the “near” face is brighter, more sharply delineated, and clearly is interposed before the “far” face. If the stimulus is rotating, even differential blur due to apparent differences in velocities of “near” and “far” parts is evident as O fixates one or the other face. The first effect, the size constancy scaling mechanism, has been treated elsewhere. Here, an hypothesis is presented that the depth effects result from the operation of another steady-state physiological mechanism that also serves to stabilize visual percepts, the apparent depth mechanism. A third such mechanism becomes evident as a real cube is “seen” in reversed perspective, one involving the perception of depth per se. In contrast to a flat “cube” all evidence of apparent depth disappears in the percept of the “reversed” real cube, yet Os still perceive depth. The integration of these three mechanisms into the over-all optical data processing system is discussed.