Wilson H R, Richards W A
Department of Ophthalmology and Visual Science, University of Chicago, Illinois 60637.
J Opt Soc Am A. 1989 Jan;6(1):106-15. doi: 10.1364/josaa.6.000106.
Visual processing of contour curvature was investigated by measuring increment thresholds for curvatures from 0.31 to 25.4 deg-1. Curvature discrimination was assessed for three classes of stimuli: simple curved contours, high-frequency bandpass-filtered contours, and low-pass-filtered contours. High-frequency bandpass filtering had no effect on discrimination at low curvatures and only a modest effect at high curvatures. In contrast, low-pass filtering caused substantial threshold elevations at all curvatures. Thus the data lead to the surprising conclusion that high-spatial-frequency, orientation-selective mechanisms dominate curvature processing over the entire range of curvatures tested, a conclusion at odds with previous suggestions that large, low-spatial-frequency filters are involved in analyzing low curvatures. The data are explained accurately by a two-process model for curvature extraction: at high curvatures the local-processing model proposed by Wilson [J. Opt. Soc. Am. A. 2, 1191 (1985)] fits the data well, whereas at low curvatures orientations are compared at points displaced a fixed distance along the tangent to the curve.
通过测量0.31至25.4度-1曲率的增量阈值，研究了轮廓曲率的视觉处理。对三类刺激评估了曲率辨别能力：简单曲线轮廓、高频带通滤波轮廓和低通滤波轮廓。高频带通滤波在低曲率时对辨别没有影响，在高曲率时只有适度影响。相比之下，低通滤波在所有曲率下都会导致阈值大幅升高。因此，数据得出了一个惊人的结论，即在测试的整个曲率范围内，高空间频率、方向选择性机制主导着曲率处理，这一结论与之前认为大的低空间频率滤波器参与分析低曲率的观点不一致。曲率提取的双过程模型能够准确解释这些数据：在高曲率时，Wilson [《美国光学学会志A》2, 1191 (1985)] 提出的局部处理模型能很好地拟合数据，而在低曲率时，沿着曲线切线以固定距离位移的点处比较方向。
