Stereoscopic Vision and the Duration of the Stimulus

Abstract

Introduction Dove (1841)* showed that stereoscopic depth could be perceived when drawings viewed in a stereoscope were illuminated by a flash of very short duration from an electric spark. The results of this experiment, and of the many others based on it subsequently, have been cited as evidence that neither convergence movements of the eyes nor proprioceptive influences from the external muscles of the eyes are necessary for a stereoscopic perception of depth. Hering's² falling-bead test, in which the bead would be in view between 1/20 and 1/50 second, and other studies such as those of Smith,³ provided similar evidence. Karpinska⁴ sought to show that these experiments succeeded, however, only when the observer knew beforehand for what he was looking. Skubich⁵ extended Karpinska's introspective experiments to include real objects and found that the depth distance between two objects such as beads could be recognized distinctly with