Marlow Phillip, Gillam Barbara J
School of Psychology, University of New South Wales, Sydney 2052, NSW, Australia.
Perception. 2011;40(12):1413-27. doi: 10.1068/p7033.
Binocular disparity produces less stereoscopic depth if the targets are separated by several degrees. It is thus possible that separation decreases the influence of stereopsis as a relative depth cue. Here, four experiments tested the strength of disparity in determining the direction of relative depth in the face of strongly conflicting relative size for a range of target separations. Under conditions of natural fixation-permitting sequential stereopsis-disparity dominated completely at small separations (0.42 degrees) but gradually gave way to relative size domination at large separations. However, when brief presentations prevented changes in fixation, disparity completely dominated at a separation of 0.5 degrees while relative size mostly dominated by 0.75 degrees - 1 degrees of separation. By varying target separation at different retinal eccentricities, we showed that separation per se was the critical factor in the dominance switch. Stereoacuity as a function of target separation for the same observers did not predict the switch from disparity to relative size. Stereoscopic dominance was found for the same small separations that are immune to stereoscopic reversals (Gillam, 1993 Perception 22 1025-1036). Our results suggest that relative disparity has a compulsory influence on perceived depth at small separations, suggesting a different mechanism from the one operating at larger separations.
如果目标之间相隔若干度，双眼视差产生的立体深度就会减少。因此，间隔可能会降低立体视觉作为一种相对深度线索的影响力。在此，四项实验测试了在一系列目标间隔下，面对强烈冲突的相对大小时，视差在确定相对深度方向上的强度。在自然注视条件下（允许连续立体视觉），视差在小间隔（0.42度）时完全占主导地位，但在大间隔时逐渐让位于相对大小主导。然而，当短暂呈现阻止注视变化时，视差在0.5度的间隔时完全占主导地位，而相对大小在0.75度至1度的间隔时大多占主导地位。通过在不同视网膜偏心度下改变目标间隔，我们表明间隔本身是主导切换的关键因素。对于相同观察者而言，作为目标间隔函数的立体视敏度并不能预测从视差到相对大小主导的切换。在对立体反转免疫的相同小间隔中发现了立体视觉主导（吉勒姆，1993年，《感知》22卷，第1025 - 1036页）。我们的结果表明，相对视差在小间隔时对感知深度有强制性影响，这表明其机制与在大间隔时起作用的机制不同。
