Global contour processing in amblyopia
Global contour processing in amblyopia
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DOI：
10.1016/j.visres.2006.10.014
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发表时间：
2007-02-01
期刊：
影响因子：
1.8
通讯作者：
Rislove, Elizabeth
中科院分区：
文献类型：
--
作者：
Levi, Dennis M.;Yu, Cong;Rislove, Elizabeth
这里描述的实验的目的是使用需要全局处理的方法来研究全局图像处理，同时消除或补偿低水平异常：可见性、形状感知和位置不确定性。为了实现这一点，我们使用了由噪声中或空白字段中的 Gabor 补丁组成的闭合图形。刺激是圆形或椭圆形轮廓，由 N 个等距的 Gabor 斑块形成。我们进行了两个单独的实验：在一个实验中，我们固定 N 并使用阶梯改变纵横比来确定阈值纵横比；在第二个实验中，我们保持纵横比恒定（纵横比阈值的两倍）并改变 N 以测量判断形状所需的元素阈值数量。我们的结果证实并扩展了之前的研究，表明患有自然弱视的人在轮廓处理方面表现出缺陷。我们的结果表明，缺陷在很大程度上取决于空间尺度（目标大小和空间频率）。全局轮廓处理中的噪声（需要轮廓链接）的缺陷比空白字段大得多。当低水平缺陷（能见度降低、位置不确定性增加和形状感知异常）最小化时，缺陷的程度是适度的，并且似乎不太依赖于敏锐度、拥挤度或立体视度。这里报告的残余赤字不能简单地归因于能见度降低或位置不确定性增加，因此我们得出结论，这些是全球轮廓隔离和整合的真正赤字。 (c) 2006 Elsevier Ltd. 保留所有权利。
The purpose of the experiments described here was to investigate global image processing using methods that require global processing while eliminating or compensating for low level abnormalities: visibility, shape perception and positional uncertainty. In order to accomplish this we used a closed figure made up of Gabor patches either in noise or on a blank field. The stimuli were circular or elliptical contours, formed by N equally spaced Gabor patches. We performed two separate experiments: in one experiment we fixed N and varied the aspect ratio using a staircase to determine the threshold aspect ratio; in the second experiment we held the aspect ratio constant (at twice the threshold aspect ratio) and varied N in order to measure the threshold number of elements required to judge the shape. Our results confirm and extend previous studies showing that humans with naturally occurring amblyopia show deficits in contour processing. Our results show that the deficits depend strongly on spatial scale (target size and spatial frequency). The deficit in global contour processing is substantially greater in noise (where contour-linking is required) than on a blank field. The magnitude of the deficits is modest when low-level deficits (reduced visibility, increased positional uncertainty, and abnormal shape perception) are minimized, and does not seem to depend much on acuity, crowding or stereoacuity. The residual deficits reported here cannot be simply ascribed to reduced visibility or increased positional uncertainty, and we therefore conclude that these are genuine deficits in global contour segregation and integration. (c) 2006 Elsevier Ltd. All rights reserved.