Bell Jason, Gheorghiu Elena, Kingdom Frederick A A
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
J Vis. 2009 Nov 10;9(12):3.1-11. doi: 10.1167/9.12.3.
We have used a curvature after-effect, or CAE, to explore whether curvature detectors are tuned for the overall orientation of a curve. CAEs were measured for half-cycle cosine-shaped contours as a function of adaptor contour orientation for a fixed test contour orientation. CAEs (i) were greatest when the adaptor and test contours had the same orientation, (ii) decreased rapidly as the orientation of the adapting contours rotated away from the test, the data being well fit by a Gaussian function with a standard deviation of 16 degrees , (iii) increased again to a secondary peak when the adapting contours were rotated 180 degrees relative to the test. Control experiments showed that the shape of the curvature-orientation tuning function could not be explained by local orientation adaptation, and that instead curvature encoding mechanisms are tuned for orientation. The secondary peak in the CAE at 180 degrees is argued to be inconsistent with curvature opponency and instead a result of the combination of polarity-selective and polarity-non-selective curvature mechanisms. The results are discussed in relation to recent psychophysical and physiological models of form processing and the possible significance of the findings with regard to symmetry processing.
我们利用一种曲率后效（CAE）来探究曲率探测器是否针对曲线的整体方向进行了调谐。针对半周期余弦形状的轮廓，在固定测试轮廓方向的情况下，测量了作为适应器轮廓方向函数的CAE。CAE具有以下特点：（i）当适应器和测试轮廓方向相同时最大；（ii）随着适应轮廓的方向偏离测试轮廓而迅速减小，数据能很好地拟合标准差为16度的高斯函数；（iii）当适应轮廓相对于测试轮廓旋转180度时再次增加到一个次峰。对照实验表明，曲率方向调谐函数的形状无法通过局部方向适应来解释，相反，曲率编码机制是针对方向进行调谐的。CAE在180度处的次峰被认为与曲率对立性不一致，而是极性选择性和非极性选择性曲率机制相结合的结果。结合近期关于形状处理的心理物理学和生理学模型对结果进行了讨论，并探讨了这些发现对于对称性处理可能具有的意义。
