ANOMALIES OF DISPARITY DETECTION IN HUMAN VISUAL-SYSTEM

Oculomotor and psychophysical depth responses were investigated in 30 individuals by use of briefly exposed disparities in the range from 0.6-4.6.degree. (1-8 centrads). The results confirmed the common occurrence of specific types of stereoanomalies within a sample from the normal population. These forms of stereoanomalies are apparently limited to coarse stereopsis and spare mechanisms concerned with fine disparity, high resolution stereopsis. A relatively high proportion of individuals manifested deficiencies of vergence eye movement under these stimulus conditions. These vergence-anomalies were characterized by a marked reduction, or absence, of either convergent or divergent eye movements to briefly exposed stimuli. The vergence-anomaly was not detrimental under normal seeing conditions since it can be present in persons with adequate binocular vision and normal fine stereopsis. The presence of vergence-anomaly was always associated with the occurrence of stereoanomaly; however, the converse was not true. The results suggest how disparity information is organized prior to its influence upon the processes of coarse stereopsis and vergence initiation.