Seeing Shape: Shape Appearances and Shape Constancy

A coin rotating back in depth in some sense presents a changing, elliptical shape. How are we to understand such (in this case) 'appearances of ellipticality'? How is the experiential sense of such shifting shape appearances related to the experiential sense of enduring shape definitive of perceived shape constancy? Is the experiential recovery of surface shape based on the prior (perhaps more fundamental) recovery of point or element 3D spatial locations?-or is the perception of shape a largely independent perceptual achievement? Do we gain access to enduring shape properties by first detecting and working from 'shape appearances'? These are some of the topics taken up in this paper.