Fig. 6 Relative perceived depth versus stimulus disparity averaged for three observers. Near (convergent) disparities only. Each curve represents a separate bar width: dots, 0.5 degrees; open circles, 0.1 degrees; triangles, 0.2 degrees; crosses, 0.4 degrees; squares, 0.8 degrees. Bar height was fixed at 0.5 degrees. Stimuli were perceived as fused only on the rising portion of the curves. (Richards W, Kay MG: Local versus global stereopsis: Two mechanisms? Vision Res 12:437, 1972)