Visual processing of contours and textures

这项申请是为了继续和发展我的研究，研究涉及处理轮廓和纹理的视觉大脑机制，使用心理物理学和大脑成像作为技术。轮廓和纹理是物体的关键组成部分，因此了解大脑如何处理轮廓和纹理对于我们理解如何识别物体至关重要。我最近开发了一种研究人类轮廓/纹理形状感知的新技术，使用具有正弦形状轮廓的轮廓(即以给定频率在空间中上下摇摆的轮廓)。如果通过凝视这些轮廓中的一个来适应它大约一分钟，则具有略微不同的物理形状频率的随后观看的轮廓的感知形状频率在远离适应形状频率的方向上移位。我把这称为形状-频率后效应，简称SFAE。通过测量在运动、深度、颜色等方面具有相同特征的适应测试组合的SFAE，并将这些SFAE与从具有不同特征(如具有不同运动方向、不同颜色等)的适应测试组合获得的SFAE进行比较，我可以确定整个特征的轮廓形状机制有多具体。这反过来将使我能够在关于大脑如何计算形状的两个假设之间进行测试：它是否使用高度简化的、卡通式的物体素描，或者，形状是从更丰富的物体表征中计算出来的吗？我对轮廓-形状处理的心理物理学研究将扩展到纹理-形状处理，并得到使用fMRI的大脑成像研究的补充。

This application is for funds to continue and develop my research into the visual brain mechanisms involved in processing contours and textures, using psychophysics and brain imaging as techniques.  Contours and textures are critical components of objects, and so an understanding of how contours and textures are handled by the brain is essential to our understanding of how objects are recognised. I have recently developed a novel technique for studying human contour/texture shape perception, using contours that have a sinusoidal shape profile (ones that 'wiggle' up and down across space with a given frequency, or 'shape-frequency'). If one adapts to one of these contours by staring at it for a minute or so, the perceived shape-frequency of a subsequently viewed contour with a slightly different physical shape-frequency is shifted in a direction away from that of the adaptation shape-frequency. I call this the 'shape-frequency after-effect', or SFAE.  By measuring SFAEs for adaptation-test combinations that have identical characteristics in terms of their motion, depth, colour etc., and compare these with SFAEs obtained from adaptation-test combinations with different characteristics (such as having different directions of motion, different colours etc.), I can determine how specific are contour-shape mechanisms for a whole range of characteristics.  This in turn will enable me to test between two hypotheses as to how the brain computes shape: does it use a highly reduced, cartoon-like sketch of an object, or is shape computed from a much richer object representation ?   My psychophysical studies of contour-shape processing will be extended to texture-shape processing and complemented by brain imaging studies using fMRI.