Abstract
A single experiment evaluated observers' ability to visually discriminate 3-D object shape, where the 3-D structure was defined by motion, texture, Lambertian shading, and occluding contours. The observers' vision was degraded to varying degrees by blurring the experimental stimuli using 2.0, 2.5, and 3.0 diopter convex lenses. The lenses reduced the observers' acuity from 1.26 min-1 (in the no blur conditions) to 0.13 min-1 (in the conditions with the most blur, 3.0 diopter lenses). This severe reduction in visual acuity (approaching legal blindness) had significant, but not meaningful, effects upon the observers' ability to discriminate 3-D shape (the observers d' values dropped from 3.6 in the no-blur conditions to 3.2 in the most severely blurred conditions). The observers' performance was facilitated by the objects' rotation in depth, regardless of the amount of blur. Our results indicate that high visual acuity is not a requirement for accurate global shape discrimination.