ABSTRACT
This chapter proposes an Angle and Ratios Together (ART) theory to reconcile robustness (constancy) and its opposite, distortion. The ART theory is tested with diamond-shaped tiles, since these are a challenge to theories of constancy. The ART theory proposes that the perception is determined by a combination of “visual angle ratio” and “angle from normal.” The first is the ratio of the visual angle of the depth of an object divided by the visual angle of the width of an object. The “angle from normal” is the angle between the line of sight joining the observer to the central vanishing point and the line of sight to the object. For convenience, the line of sight intersects the object on the base of the object where it is farthest laterally from the observer. Each subject, tested individually, judged the depth of an indicated tile relative to the width, with the width of every tile set at 100.
