Woodward M, Ettinger E R, Yager D
Schnurmacher Institute for Vision Research, SUNY College of Optometry, NY 10010.
Spat Vis. 1985;1(1):13-7. doi: 10.1163/156856885x00035.
Spatial frequency difference thresholds for sinewave gratings near contrast threshold were measured using a two-alternative forced-choice technique, and the threshold frequency differences were plotted as a proportion of standard frequency for standards from 2 to 7 cycles/degree. This function shows reliable local maxima and minima, and these features are more pronounced than they are when stimuli of 30% contrast are used. This result is consistent with the notion that at low contrasts, fewer spatial frequency channels are above threshold in the area of the visual field covered by the stimulus than when the stimulus is at high contrast.
使用二选一强制选择技术测量接近对比度阈值的正弦波光栅的空间频率差异阈值，并将阈值频率差异绘制为标准频率的比例，标准频率范围为2至7周/度。该函数显示出可靠的局部最大值和最小值，并且这些特征比使用30%对比度刺激时更明显。这一结果与以下观点一致：在低对比度下，与高对比度刺激相比，刺激所覆盖的视野区域中高于阈值的空间频率通道更少。
