Thomas J P
Department of Psychology, University of California, Los Angeles 90024.
J Opt Soc Am A. 1989 Jul;6(7):1102-11. doi: 10.1364/josaa.6.001102.
Experiments were done to examine the minimum separation with respect to spatial frequency required for two superimposed gratings to be processed independently in the visual system. The contrasts of all stimuli were well above the detection threshold. The lack of independent processing was measured by the observers' failure to see both gratings as separate sinusoids; changes in the apparent contrast or spatial frequency of one grating when the other was present; and changes in the ability to discriminate small differences in the contrast or spatial frequency of one grating when the second grating was present. All measures point to a lack of independent processing when the gratings differ by less than 2 octaves. When they differ by more than 2 octaves, they are seen as separate, apparent spatial frequency is not altered systematically, and discrimination performance essentially is unaffected. However, the apparent contrast of the high-frequency grating varies, depending on whether its bars are seen against the bright bars or against the dark bars of the low-frequency grating.
进行了实验，以研究在视觉系统中两个叠加光栅要被独立处理所需的关于空间频率的最小间隔。所有刺激的对比度都远高于检测阈值。通过观察者无法将两个光栅视为单独的正弦波来衡量缺乏独立处理；当另一个光栅存在时，一个光栅的表观对比度或空间频率的变化；以及当第二个光栅存在时，区分一个光栅的对比度或空间频率的微小差异的能力变化。所有测量结果都表明，当光栅的差异小于2倍频程时，缺乏独立处理。当它们的差异超过2倍频程时，它们被视为分开的，表观空间频率不会系统地改变，并且辨别性能基本上不受影响。然而，高频光栅的表观对比度会有所不同，这取决于其条纹是与低频光栅的亮条纹相对还是与暗条纹相对。
