Brown A M
Ohio State University, College of Optometry, Columbus 43210-1240.
Vision Res. 1994 Aug;34(15):1947-64. doi: 10.1016/0042-6989(94)90025-6.
In these experiments, the amounts of intrinsic contrast noise and contrast-dependent noise were independently estimated from optokinetic nystagmus (OKN) contrast discrimination thresholds in 7-week-old human infants and adults. This report shows that the poor contrast sensitivity of infants occurs mostly because there is about 106 times more intrinsic contrast noise in the infant visual system than in the adult visual system. The intrinsic contrast noise is combined nearly linearly with the visual signal in infancy, whereas noise and visual signal are combined in a highly non-linear way for adults. The standard deviation of the visual signal differs between infants and adults by a factor of about 2 for OKN data and a factor of 13 for behavioral data. The large amount of intrinsic contrast noise found by this analysis is quantitatively consistent with data obtained by forced-choice preferential looking (FPL), and visually evoked potential (VEP) contrast sensitivity is correctly predicted to be near adult values in infancy.
在这些实验中，通过对7周大的人类婴儿和成年人的视动性眼震（OKN）对比度辨别阈值，分别独立估计了内在对比度噪声和对比度相关噪声的量。本报告表明，婴儿对比度敏感性较差，主要是因为婴儿视觉系统中的内在对比度噪声比成人视觉系统中多约106倍。在婴儿期，内在对比度噪声几乎与视觉信号呈线性组合，而在成年人中，噪声和视觉信号以高度非线性的方式组合。对于OKN数据，婴儿和成年人视觉信号的标准差相差约2倍，对于行为数据则相差13倍。该分析发现的大量内在对比度噪声在数量上与通过强迫选择优先注视（FPL）获得的数据一致，并且视觉诱发电位（VEP）对比度敏感性在婴儿期被正确预测为接近成人值。
