Chen B, Makous W, Williams D R
Center for Visual Science, University of Rochester, NY 14627.
Vision Res. 1993 Feb;33(3):413-27. doi: 10.1016/0042-6989(93)90095-e.
Observers viewing two superimposed laser interference fringes of nearly equal spatial frequency see an illusory grating of low spatial frequency, even when the spatial frequency of the fringes exceeds the resolution limit. This grating is a product of nonlinear distortion within the visual system [MacLeod, Williams and Makous (1992) Vision Research, 32, 347-363]. By separately manipulating the spatial frequencies of the interference fringes and the distortion gratings, we decomposed the contrast sensitivity function into two serial components separated by the nonlinear process. Losses in the optics of the eye were avoided by use of laser interferometry. Spatial summation preceding the nonlinear stage was restricted to the light-collecting area of individual cones and was directly proportional to the diameters of cone inner segments at three retinal eccentricities; this suggests that light is trapped within cones at the level of their inner segments. Even 30 degrees from the fovea, the nonlinear stage precedes the site where separate signals from individual cones are no longer maintained; this leads us to suggest that the nonlinear process lies within the retina. In addition, spatial antagonism precedes the nonlinear stage; this places the nonlinear process at a site following the outer segments of the cones. Dichoptic presentation of the interference fringes failed to produce illusory gratings; that is, the nonlinearities within the binocular pathway do not produce distortions like those produced by the monocular nonlinearity.
观察者在观看两个空间频率几乎相等的叠加激光干涉条纹时，即使条纹的空间频率超过了分辨率极限，也会看到一个低空间频率的虚幻光栅。这个光栅是视觉系统内非线性失真的产物[麦克劳德、威廉姆斯和马库斯（1992年）《视觉研究》，32卷，347 - 363页]。通过分别操纵干涉条纹和失真光栅的空间频率，我们将对比敏感度函数分解为两个由非线性过程分隔的串行分量。通过使用激光干涉测量法避免了眼睛光学系统中的损失。非线性阶段之前的空间总和被限制在单个视锥细胞的光收集区域内，并且与三个视网膜离心率下视锥细胞内节的直径成正比；这表明光在视锥细胞内节水平被捕获在视锥细胞内。即使在离中央凹30度的位置，非线性阶段也先于单个视锥细胞的单独信号不再维持的位置；这使我们认为非线性过程位于视网膜内。此外，空间拮抗作用先于非线性阶段；这将非线性过程置于视锥细胞外节之后的位置。干涉条纹的双眼呈现未能产生虚幻光栅；也就是说，双眼通路内的非线性不会产生像单眼非线性那样的失真。
