Symmetry as a cue to object and scene representations in human visual cortex

人类视觉系统必须将到达视网膜的2D图像转换为视觉场景的3D表示，我们可以用它来感知和与世界互动。视觉对称是这一过程的一个重要线索，并被发现在视觉敏感的大脑区域引起强烈的反应。大多数关于视觉感知中对称的研究使用了有限的刺激参数：(1)反射而不是其他类型的对称，(2)单个图像位置的对称轴，(3)正面平行图像平面的对称。为了解决这些限制，并加强我们对对称作为物体和场景感知线索的理解，拟议的研究计划建立在最近的进展之上。项目1将探索如何通过对称类型、平铺和倾斜来调节对对称的敏感性。我之前的工作表明，视觉脑区对对称比反射更敏感，而对称的纹理在平面上平铺会产生强烈的视觉反应，但平铺和对称类型如何调节大脑区域的活动尚不清楚。虽然对称现象在自然世界中普遍存在，但对称的像平面投射到视网膜上的现象在自然观察中很少发生，这一事实激发了扭曲操纵的动机。因此，人们很自然地会问，当世界上的对称性在视网膜上产生“扭曲”的投影时，视觉系统能在多大程度上克服这种扭曲。为了解决这些操作差异驱动人类视觉皮层中不同的对称敏感子网络的假设，我将使用脑成像方法以高时空精度测量对称响应的幅度，时间和皮层来源。该项目将提供视觉系统中对称调谐的更完整的表征，并有可能连接文献的不同分支。项目2将解决这样一个假设，即对对称的敏感性是婴儿和幼儿在视觉环境中接触对称时学习的结果，因此，人类视觉皮层对对称的反应应该在早期发展中发生变化。我将通过比较婴儿和成人的对称反应来验证这一点。据我们所知，这将是第一个研究婴儿或幼儿对称感知的脑成像研究。这项研究将揭示在早期视觉发展中可能存在的对对称的任何敏感性，并为对称编码如何随着暴露于自然世界而变化提供线索。本研究计划利用控制良好的刺激结合最先进的脑成像技术，解决了对称和3D物体和场景感知文献之间的重要差距。这些发现有可能加深我们对对称在自然视觉中的作用的理解，并为视觉神经科学和计算机视觉的相关研究提供信息。

The human visual system must convert the 2D image arriving at the retina into a 3D representation of the visual scene that we can use to perceive and interact with the world. Visual symmetry is an important cue to this process and has been found to elicit strong responses in visually responsive brain areas. Most studies of symmetry in the context of visual perception have used a limited range of stimulus parameters: (1) Reflection rather than other types of symmetry, (2) symmetry axes at a single image location, and (3) symmetries in the fronto-parallel image plane. The proposed research program builds on recent advances in order to address these limitations and enhance our understanding of symmetry as a cue to object and scene perception. Project 1 will explore how sensitivity to symmetry is modulated by symmetry type, tiling and skew. My prior work shows that visual brain areas are sensitive to symmetries other than reflection, and that textures in which symmetries are tiled across the plane produce robust visual responses, but it is unclear how tiling and symmetry type modulate activity across brain areas. The skew manipulation is motivated by the fact that although symmetries commonly occur in the natural world, symmetrical image-plane projections onto the retina rarely occur under natural viewing. It is thus natural to ask to what extent the visual system can overcome distortions introduced when symmetries in the world produce "skewed" projections onto the retina. To address the hypothesis that these manipulations differentially drive distinct symmetry-sensitive sub-networks in human visual cortex, I will use brain imaging methods to measure the amplitude, timing and cortical sources of responses to symmetry with high temporal and spatial precision. This project will provide a more complete characterization of symmetry tuning in the visual system and has the potential to connect distinct branches of the literature. Project 2 will address the hypothesis that sensitivity to symmetry is the result of learning as infants and young children are exposed to symmetries in their visual environment, and that responses to symmetry in human visual cortex should therefore change over early development. I will test this by comparing symmetry responses in infants and adults. To our knowledge, this will be the first brain imaging study to investigate symmetry perception in infants or young children. This study will reveal any sensitivity to symmetry that may exist in early visual development, and provide cues as to how encoding of symmetry changes with exposure to the natural world. This research program addresses an important gap between the symmetry and 3D object and scene perception literatures using well-controlled stimuli combined with state-of-the-art brain imaging techniques. The findings have the potential to deepen our understanding of the role of symmetry in natural vision, and inform related research in visual neuroscience and computer vision.