Effects of the spatial frequency of test and reference stimuli on stereo-thresholds

The perceived depth of adjacent regions of stereoscopic stimuli may be influenced, in part, by differences in the spatial frequency composition of adjacent stimuli. Consequently, it would be predicted that, if the test and reference stimuli differ in their spatial frequency composition, depth discrimination thresholds should be asymmetric about the retinal disparity of the reference stimulus. We measured depth discrimination thresholds with test and reference stimuli that differed by up to 2 octaves in their spatial frequency composition. Stereo-thresholds decreased as a function of spatial frequency to about 2-4 c/deg and were then constant. However, in contrast to the predicted effects, our results show that, for the range of spatial frequencies used, differences of up to 2 octaves in spatial frequency, between test and reference stimuli, do not affect depth discrimination thresholds.