An automated system for determining psychophysical stereo-threshold to dynamic random dot stimuli

We describe an approach to the problem of measuring stereoscopic thresholds to images of random dot stereograms. This involves using an Apple Macintosh computer with 640x480-pixel monitor with shutter glasses alternating the view to left and right eyes, while simultaneously changing the horizontal disparity of a pair of images on the screen so that it has ‘depth’. While this approach is not new, the process of generating the images during the operation of the program is novel and eliminates the requirement for massive libraries of images. A second feature is the inclusion of maximum likelihood threshold estimation in the operation of the program, so that psychophysical thresholds can be measured, either in the complete image, or separately in the right and left visual fields. This system is now in operation in Germany and being duplicated in Australia.