title: A method for quantifying visual field inhomogeneities.
abstract: It is well known that performance is not homogeneous across the visual field, even at isoeccentric locations. Several inhomogeneities in particular have been identified - a Horizontal-Vertical Anisotropy (HVA - better performance in the horizontal than in the vertical direction); a Vertical Asymmetry (VA - better performance in the lower than the upper visual field); and a Vertical Meridian Asymmetry (VMA - better performance below than above the point of fixation on the vertical meridian). Performance has also been reported to be particularly poor at the location directly above the point of fixation, i.e., the "North" (N) location and sometimes at the location directly below the point of fixation, i.e., the "South" (S) location. These phenomena are typically characterized by statistics that compare performance across the visual field to a homogeneous (circular) model. Here we propose an alternative method for assessing visual field inhomogeneities, which involves comparing performance to an elliptical model of the visual field. We maintain that this method provides a more robust analysis of visual field inhomogeneities because it does not overestimate the North and South effects.
authors.affiliation: Department of Psychology, University of Illinois at Chicago, United States.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Anderson
authors.affiliation: Department of Psychological Science, Carthage College, United States; Department of Psychology, University of Illinois at Chicago, United States. Electronic address: lcameron@carthage.edu.
authors.forename: E
authors.initials: E
authors.lastname: Leslie Cameron
authors.affiliation: Department of Psychology, University of Illinois at Chicago, United States; Laboratory for Integrative Neuroscience, University of Illinois at Chicago, United States.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Levine
mesh_terms: D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D005403:Fixation, Ocular; D006801:Humans; D008962:Models, Theoretical; D010775:Photic Stimulation / Q000379:methods; D013028:Space Perception / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*
keywords: Ellipse; HVA; VMA; Vertical asymmetry; Visual field inhomogeneity