title: Conditions for view invariance in the neural response to visual symmetry.
abstract: Symmetry detection is slow when patterns are distorted by perspective, perhaps due to a time-consuming normalization process, or because discrimination relies on remaining weaker regularities in the retinal image. Participants viewed symmetrical or random dot patterns, either in a frontoparallel or slanted plane (±50°). One group performed a color discrimination task, while another performed a regularity discrimination task. We measured a symmetry-related event-related potential (ERP), beginning around 300 ms. During color discrimination, the ERP was reduced for slanted patterns, indexing only the remaining retinal structure. During regularity discrimination, the same ERP was view invariant, and identical for frontoparallel or slanted presentation. We conclude that normalization occurs rapidly during active symmetry discrimination, while symmetry-sensitive networks respond only to regularity in the retinal image when people are attending to other features.
authors.affiliation: Department of Psychological Sciences, University of Liverpool, Liverpool, UK.
authors.forename: Alexis D J
authors.initials: AD
authors.lastname: Makin
authors.forename: Giulia
authors.initials: G
authors.lastname: Rampone
authors.forename: Marco
authors.initials: M
authors.lastname: Bertamini
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Event-related potentials; Perspective distortion; Sustained posterior negativity; Symmetry; View invariance