Allen D, Norcia A M, Tyler C W
Am J Optom Physiol Opt. 1986 Jun;63(6):442-9. doi: 10.1097/00006324-198606000-00008.
We measured the human contrast sensitivity function (CSF) both electrophysiologically with the steady-state visual evoked potential (VEP) and psychophysically using a method of ascending limits. VEP contrast thresholds were determined using a rapid recording technique in which the contrast of a counterphase modulated sine wave grating was swept logarithmically from 0.5 to 40% over a period of 10 s. For this pattern reversal stimulus the amplitude and phase of the second harmonic response as a function of contrast were measured using a discrete Fourier transform (DFT). Psychophysical thresholds were determined on the same trials used to record the VEP. Near threshold the VEP amplitude vs. contrast function was approximately linear and VEP contrast thresholds were estimated by a linear extrapolation to zero amplitude. The contrast thresholds obtained by the two methods correlated at 0.914 for 5 observers, with a mean discrepancy of only 12%. At higher contrasts, the VEP amplitude vs. contrast function often became nonmonotonic, sometimes showing two amplitude peaks.
我们通过稳态视觉诱发电位（VEP）以电生理方式测量了人类对比敏感度函数（CSF），并使用极限递增法以心理物理学方式进行了测量。VEP对比阈值是使用一种快速记录技术确定的，在该技术中，反相调制正弦波光栅的对比度在10秒内从0.5对数扫至40%。对于这种模式反转刺激，使用离散傅里叶变换（DFT）测量二次谐波响应的幅度和相位作为对比度的函数。心理物理学阈值是在用于记录VEP的相同试验中确定的。在接近阈值时，VEP幅度与对比度函数近似呈线性，VEP对比阈值通过线性外推至零幅度来估计。5名观察者通过两种方法获得的对比阈值的相关性为0.914，平均差异仅为12%。在较高对比度下，VEP幅度与对比度函数通常变得非单调，有时会出现两个幅度峰值。
