The tilt aftereffect in plaids and gratings: Channel codes, local signs and ''patchwise'' transforms
The tilt aftereffect in plaids and gratings: Channel codes, local signs and ''patchwise'' transforms
复制标题
DOI：
10.1016/0042-6989(95)00212-x
复制
发表时间：
1996-05-01
期刊：
影响因子：
1.8
通讯作者：
Georgeson, MA
中科院分区：
文献类型：
--
作者：
Meese, TS;Georgeson, MA
由两个垂直倾斜+/-45°的正弦栅格制成的阈值以上格子的感知结构通常类似于模糊的棋盘，物理地增加部件远离垂直的倾斜将水平拉长图案，产生矩形格子。我们询问通过适应垂直栅导出的部件的虚幻倾斜是否也会使格子明显延长，使用阶梯法，我们发现，在适应后，部件方向必须设置为更接近垂直3-4°，以保持正方形、棋盘状的外观，这意味着+/-45°格子确实看起来拉长，这一结果表明，倾斜后效适应不仅会扭曲一维图案的方向，而且还会改变特征的相对位置，即使它们的方向没有改变，这在过滤器模型中很难解释，这些模型(通常隐含地)假设每个感受场带有一个固定的表示其在视网膜阵列中的位置。我们考虑一种表示，其中图像的局部斑块由二维傅里叶变换的系数编码，具有简单的减法适应模型，我们表明每个斑块携带的空间信息将以观察到的格子和栅格的方式失真，自适应后的感知结构是扭曲的和连贯的，而不是碎片化的，这一事实表明了一个额外的、更全局的过程，即局部块被组合成一个连贯的、合成的“神经图像”。我们提供了一个简单的原理来建立这种一致性，如果局部块的位置被调整以最大化合成图像的对比度能量，那么块的空间失真(由选择性自适应引起)被带到合成的全局结构中，从而解决了信道码和局部符号之间的冲突，但结果是感知失真。版权所有(C)1996爱思唯尔科学有限公司。
The perceived structure of a suprathreshold plaid made from two sinusoidal gratings tilted +/- 45 deg from vertical usually resembles a blurred checkerboard, Physically increasing the tilt of the components away from vertical elongates the pattern horizontally, yielding rectangular checks, We asked whether illusory tilt of the components induced by adaptation to a vertical grating would also give apparent elongation of the checks, Using a staircase method, we found that after adaptation the component orientations had to be set 3-4 deg closer to vertical to maintain a square, checkerboard-like appearance, implying that the +/- 45 deg plaid did appear elongated, This result suggests that the tilt aftereffect adaptation not only distorts the orientation of 1-D patterns but can also change the relative location of features, even when their orientation is not altered, This is not easy to explain within filter models that (often implicitly) assume each receptive field carries a fixed ''local sign'' indicating its position within the retinal array, We consider a representation in which localized patches of the image are encoded by the coefficients of a 2-D Fourier-like transform, With a simple subtractive model of adaptation, we show that the spatial information carried by each patch would be distorted in just the way observed for plaids and gratings, The fact that perceived structure is both distorted and coherent, not fragmented, after adaptation suggests an additional, more global process whereby local patches are combined to form a coherent, composite ''neural image'', We offer a simple principle that could establish this coherence, If the positions of local patches are adjusted so as to maximize the contrast energy of the composite image, then the spatial distortions of the patches (induced by selective adaptation) are carried through to the global structure of the composite, Thus, the conflict between channel codes and local signs is resolved, but perceptual distortion is the result. Copyright (C) 1996 Elsevier Science Ltd.