van de Grind W A, Koenderink J J, van Doorn A J
J Opt Soc Am A. 1987 Aug;4(8):1643-52. doi: 10.1364/josaa.4.001643.
The detection of coherent motion was studied in stroboscopically displayed moving random-dot patterns disturbed by incoherent noise. We determined the threshold signal-to-noise ratio S as a function of velocity V at eccentricities of 0 degrees, 3 degrees, 6 degrees, 12 degrees, 24 degrees, 48 degrees in the temporal visual field of the right eye. At each eccentricity the measurements of S = f(V) were repeated for a range of rms contrast values from 60% (0 dB) in steps of 3 dB down to 1.9% (-30 dB). All stimuli were scaled with eccentricity to keep the ratio of pixel size to acuity constant (about 2). It is shown that the S values in our paradigm are never determined by contrast-threshold effects. They are true correlational thresholds. Bilocal movement detectors are assumed to underlie the detection of coherent motion. The bilocal correlation proves to be rather insensitive to rms contrast down to contrast levels of about 10%. Despite the eccentricity scaling, which is quite effective at high contrast levels, differences between the eccentricities become noticeable at lower contrast levels (below about 30-20%). The fovea is the least, and the far periphery the most, resistent to contrast degradation.
我们在受非相干噪声干扰的频闪显示移动随机点图案中研究了相干运动的检测。我们确定了右眼颞侧视野中0度、3度、6度、12度、24度、48度偏心率下阈值信噪比S作为速度V的函数。在每个偏心率下，对于均方根对比度值从60%（0分贝）以3分贝为步长降至1.9%（-30分贝）的范围，重复测量S = f(V)。所有刺激均根据偏心率进行缩放，以保持像素大小与视敏度的比率恒定（约为2）。结果表明，我们实验范式中的S值从未由对比度阈值效应决定。它们是真正的相关阈值。假设双局部运动探测器是相干运动检测的基础。双局部相关性被证明对均方根对比度相当不敏感，直至对比度水平约为10%。尽管偏心率缩放在高对比度水平下相当有效，但在较低对比度水平（低于约30 - 20%）时，偏心率之间的差异变得明显。中央凹对对比度降低的抵抗力最小，而远周边的抵抗力最大。
