Greenlee M W, Magnussen S
Vision Res. 1987;27(2):249-55. doi: 10.1016/0042-6989(87)90187-8.
Adaptation to a high contrast sinewave grating of 1 c/deg spatial frequency causes a large increase in the contrast threshold for a 1 c/deg test grating, but fails to raise the threshold for a squarewave grating of 0.33 c/deg, although the sensitivity of the "channel" tuned to both the third and fifth harmonic components of the squarewave test grating should be thoroughly suppressed. Following sequential adaptation to sinewave gratings of 1 and 3 c/deg spatial frequency, detection of squarewave gratings at 0.33 c/deg likewise remains unaffected. In contrast, after adaptation to a 0.33 c/deg squarewave grating with missing fundamental the contrast threshold for a squarewave test grating of the same frequency is increased by 0.25 log unit, although the higher harmonic component frequencies are less affected than by sequential sinewave adaptation. The results suggest that independent spatial frequency channels detecting harmonic components are not alone sufficient to account for the visibility of low frequency squarewaves.
适应1 c/deg空间频率的高对比度正弦波光栅会导致1 c/deg测试光栅的对比度阈值大幅增加，但不会提高0.33 c/deg方波光栅的阈值，尽管调谐到方波测试光栅的三次和五次谐波分量的“通道”灵敏度应被完全抑制。在相继适应1和3 c/deg空间频率的正弦波光栅后，0.33 c/deg方波光栅的检测同样不受影响。相比之下，在适应具有缺失基频的0.33 c/deg方波光栅后，相同频率的方波测试光栅的对比度阈值增加了0.25对数单位，尽管高次谐波分量频率受到的影响小于相继的正弦波适应。结果表明，检测谐波分量的独立空间频率通道不足以单独解释低频方波的可见性。
