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。

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.