Brain Responses To Symmetries In Naturalistic Novel Three-Dimensional Objects

Human brains are sensitive to symmetry, especially vertical reflection, which is present in human faces and many other biological forms. However, symmetries in most visual scenes are rotated relative to the observer’s viewing location, failing to produce symmetry in the retinal image. We investigated the differences between perspective-distorted symmetry, and images that produce symmetry on the retina, and measured the association between responses to symmetry and autism spectrum disorder (ASD). We found that perspective-distorted symmetry with cues to 3D shape elicited responses, and both image-level and perspective distorted 3D symmetry elicited stronger responses than 2D symmetry. 3D image-level symmetry created stronger responses than 3D perspective-distorted symmetry. Lastly, there was no association between responses to symmetry and ASD. We conclude that symmetry processing occurs in the absence of a symmetry-related task, even for perspective-distorted symmetry. Additionally, there may not be any association between conditions that affect global processing and symmetry processing.