Localization of speed differences of context stimuli during fixation and smooth pursuit eye movements
Localization of speed differences of context stimuli during fixation and smooth pursuit eye movements
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DOI：
10.1016/j.visres.2010.07.028
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发表时间：
2010-12-01
期刊：
影响因子：
1.8
通讯作者：
Gegenfurtner, Karl R.
中科院分区：
文献类型：
--
作者：
Braun, Doris I.;Schutz, Alexander C.;Gegenfurtner, Karl R.
视觉系统只能通过视网膜图像运动的改变来检测运动物体的速度变化，而视网膜图像运动也会受到头部或眼球运动的影响。本文研究了平滑追踪眼球运动是否影响对大背景刺激的短速度扰动的定位能力。在两种背景刺激下，测量了定位辨别和检测两种背景刺激之一的速度扰动的心理物理阈值。注视试验的主要条件在追踪试验中，受试者注视中心静止点，他们的眼睛跟随水平移动的目标。背景刺激是垂直取向的正弦波光栅，其同时在注视或追踪目标的上方和下方以与追踪目标相同或不同的速度沿相同方向移动1秒。在移动期间，其中一个光栅突然改变其速度500 ms并恢复到原来的速度，要求观察者辨别速度变化的位置（二选一空间强迫选择任务）（二区间强迫选择）和速度扰动类型的辨别阈值在正常范围内，速度扰动位置的韦伯分数阈值从10-15%急剧增加到30-50%。当视网膜运动主要由背景运动引起时，如注视或慢追踪时，定位阈值特别高，而当视网膜运动主要由追踪引起时，定位阈值显著降低。这一结果表明，视网膜运动的起源无论是由物体运动引起还是由自主追踪引起都是重要的。影响两个外围运动物体之一的速度扰动对于视觉系统来说是非常复杂的，这可能是由于相对运动的主导作用。在平滑追踪期间，通过从追踪获得的附加信息（例如推论放电），似乎可以提高定位非中央凹物体的速度扰动的能力（C）2010 Elsevier Ltd保留所有权利
The visual system can detect speed changes of moving objects only by means of alterations of retinal image motion which is also subject to changes induced by head or eye movements Here we investigated whether smooth pursuit eye movements affect the ability to localize short speed perturbations of large context stimuli Psychophysical thresholds for localization discrimination and detection of speed perturbations in one of two context stimuli were measured under two main conditions in fixation trials subjects fixated a central stationary spot in pursuit trials they followed a horizontally moving target with their eyes Context stimuli were vertically oriented sine wave gratings moving simultaneously above and below the fixation or pursuit target for one second in the same direction at the same or a different speed as the pursuit target During the movement one of the gratings suddenly changed its speed for 500 ms and returned to its original speed Observers were asked to discern the location of the speed change (two-alternative spatial forced choice task) While detection (two-interval forced choice) and discrimination thresholds for the kind of speed perturbation were in the normal range of Weber fractions of 10-15% thresholds for the location of the speed perturbation were dramatically increased to 30-50% Localization thresholds were particularly high when the retinal motion was mainly due to the context movements as during fixation or slow pursuit and significantly reduced when the retinal motion was mainly due to pursuit This result indicates that the origin of retinal motion whether it is caused by object motion or by voluntary pursuit is important We conclude that the localization of speed perturbations affecting one of two peripheral moving objects is exceedingly complicated for the visual system probably due to the dominance of relative motion During smooth pursuit the ability to localize speed perturbations of non-foveated objects seems to be improved by additional information gained from pursuit such as corollary discharge (C) 2010 Elsevier Ltd All rights reserved