Three-dimensional object constancy: Coherence of a simulated rotating sphere in noise

Southeast Missouri State University, Cape Girardeau, Missouri 63 701 The maintenance of constant and coherent percepts of three-dimensional objects, even in the midst of visual noise, is important to our ability to navigate the environment. In the present experiments, observers viewed computer-animated simulations of three-dimensional spheres rotating around the vertical axis in depth. In the first experiment, the addition of noise in the form of randomly moving display elements reduced subjects’ judgments of depth and the accuracy of their rotation-direction judgments, although the phenomenal appearance of three-dimensional structure was maintained throughout. In the second experiment, a change from frame to frame in the orientation of the vectors that composed the simulation reduced, but did not destroy, perceived depth and rotation-direction accuracy. The effect of a change in orientation between vectors of successive frames of a simulation depended upon the length of those vectors. It is argued thatdynamic perspective— the information provided by movement and perspective together—is a significant factor in the maintenance of threedimensional object constancy.