Disparity Processing in Sensory and Motor Functions

追溯到154年前惠斯顿时代的传统理论认为，立体深度感知是在视觉皮层的早期由左右眼视网膜图像之间的差异（视网膜视差）刺激的。另外，立体视觉和双眼眼球运动可以通过两个眼睛图像感知方向之间的双眼差异（头部中心差异）在大脑的感觉运动区域受到刺激。这些感知到的方向是由视网膜图像定位和眼睛位置信息的结合产生的。在正常的观看条件下，视网膜视差与头部中心视差无法区分，因此无法确定立体视觉是基于哪一种。然而，当一个短暂闪过的目标在快速眼动（扫视）开始时出现一个小的眼间时间延迟时，这两种形式的视差确实有不同的大小。扫视引起两只眼睛感知方向的不平等扭曲，这些差异产生立体深度。这是第一个证明眼球运动可以影响立体视觉的双眼视差刺激，并且双眼视差在头部中心坐标中表示。在美国国家科学基金会（National Science Foundation）的支持下，肖尔博士将研究快速（跳眼）眼球运动是如何导致立体深度感知失真的。这些深度扭曲揭示了大脑如何表现刺激立体视觉和双眼运动的双眼差异。除了提高我们对立体视觉的基本理解外，这项工作还涉及眼球运动如何影响计算机模拟的立体显示器所刺激的深度准确性，这种显示器向两只眼睛分别呈现交替的帧。由此产生的空间扭曲可能影响深度定位和瞄准任务的性能。

Traditional theories going back 154 years to Wheatstone propose that stereoscopic depth perception is stimulated early in the visual cortex by disparities between the retinal images on the left and right eyes (retinal disparity). Alternatively, stereopsis and binocular eye movements could be stimulated in sensory-motor regions of the brain by binocular disparities between perceived directions of the two ocular images (head-centric disparity). These perceived directions result from a combination of retinal image location and eye position information. Under normal viewing conditions, retinal disparities are indistinguishable from headcentric disparities, so it is not possible to determine which stereoscopic vision is based on. However, the two forms of disparity do have different magnitudes when a briefly flashed target is presented with a small interocular time delay near the onset of a rapid eye-movement (saccade). The saccade causes unequal distortions of perceived direction by the two eyes, and these differences produce stereo-depth. This is the first evidence that eye movements can influence binocular disparity stimuli for stereopsis and that binocular disparity is represented in headcentric coordinates.With support of the National Science Foundation, Dr. Schor will investigate how rapid (saccadic) eye movements produce distortions of stereoscopic-depth perception. These depth distortions reveal how the brain represents binocular disparities that stimulate stereopsis and binocular eye movements. In addition to improving our basic understanding of stereopsis, this work has implications concerning how eye movements might influence the accuracy of depth stimulated by computer-simulated stereo displays that present alternate frames to each of the two eyes. The resulting distortions of space could influence performance in depth localization and aiming tasks.