Anomalous Stereoscopic Depth Perception*

Normal or complete stereoscopic depth perception is based upon at least two and probably three mechanisms. These mechanisms may be isolated by studying depth judgments made by stereoanomalous individuals who are unable to discriminate disparities over wide ranges of disparity. The nature of the reductions observed among these stereoanomalous observers suggests that at least three ranges of the disparity are sampled in order to create three different pools of binocular activity. The pools correspond roughly to crossed, near-zero, and uncrossed disparities.