Three-dimensional computer graphic displays contain the information that viewers use to understand the shapes of depicted objects. We have devised techniques for carrying out experiments that examine the factors that influence the accuracy of this shape understanding. We construct simple convex objects using the superquadric equation. The objects are graphically rendered and displayed in rotation in a variety of perceptual tasks. In this paper, we summarize the results of our previous experiments that examined the relative contribution of shading and occluding contour, and the effects of including specular reflectance. We also report experiments designed to determine the influence that light source direction and surface striping have on shape understanding.