Ukkonen O, Rovamo J, Näsänen R
Department of Vision Sciences, University of Aston, Birmingham, U.K.
Optom Vis Sci. 1995 Jun;72(6):387-95. doi: 10.1097/00006324-199506000-00006.
We studied the effect of spatial location and orientation uncertainty on r.m.s. contrast sensitivity with and without external spatial noise in peripheral and foveal vision.
In the first experiment we used a small circular cosine grating with randomized location embedded in spatial noise and exposed for 33 to 533 ms in peripheral vision. In the second experiment, performed with and without noise, we varied the randomization range of stimulus location in a foveal search task with free eye movements and an unlimited exposure time. In the third experiment we used a vertical cosine grating exposed for 500 ms and varied the randomization range of aperture orientation in the fovea with and without noise.
Uncertainty of spatial location had no effect on r.m.s. contrast sensitivity in the periphery or fovea. However, sensitivity decreased with increasing randomization range of aperture orientation in the fovea.
Uncertainty of spatial location had no effect because the accuracy of positional information is inherently poor in peripheral vision, whereas in the fovea the effect of location uncertainty was compensated for by searching eye movements. Randomization of aperture orientation reduced contrast sensitivity in the fovea because in this case the effect of randomization could not be compensated for.
我们研究了空间位置和方向不确定性对周边视觉和中央凹视觉中均方根对比度敏感度的影响，有无外部空间噪声时的情况均在研究范围内。
在第一个实验中，我们使用了一个嵌入空间噪声中的位置随机的小圆形余弦光栅，在外周视觉中曝光33至533毫秒。在第二个实验中，在有噪声和无噪声的情况下进行，我们在一个可自由眼动且曝光时间无限制的中央凹搜索任务中改变刺激位置的随机范围。在第三个实验中，我们使用一个垂直余弦光栅曝光500毫秒，在有噪声和无噪声的情况下改变中央凹中孔径方向的随机范围。
空间位置的不确定性对外周或中央凹的均方根对比度敏感度没有影响。然而，中央凹中孔径方向的随机范围增加时，敏感度会降低。
空间位置的不确定性没有影响是因为外周视觉中位置信息的准确性本来就很差，而在中央凹中，位置不确定性的影响通过搜索性眼动得到了补偿。孔径方向的随机化降低了中央凹中的对比度敏感度，因为在这种情况下随机化的影响无法得到补偿。
