Development of a computer-based system for studying human stereopsis: contribution to the study of human speed of detection of visual depth

We have developed a computer-based method for measuring the speed of human visual depth perception (stereolatency). Since it needs only a personal computer and special glasses, our method is easier to use than other techniques, which require electromechanical devices. We have tested 25 normal subjects and have found a mean stereolatency of 258.3 ms, which is similar to that reported by others with the use of such electromechanical methods. We have also identified a group of normal subjects who have stereolatencies in excess of 500 ms, who probably do not use stereoscopic vision in everyday life. Finally, the use of different experimental paradigms has provided evidence that increased environmental luminance is able to speed up stereoscopic perception. We postulate that such effect is due to an excitatory effect on retinal photoreceptors, which are brought to a level of hyperpolarization nearer the threshold for the production of afferent impulses to the visual system, resulting in faster phototransduction and shorter stereolatencies.