title: Individual differences in visual field shape modulate the effects of attention on the lower visual field advantage in crowding.
abstract: It has previously been reported that visual crowding of a target by flankers is stronger in the upper visual field than in the lower, and this finding has been attributed to greater attentional resolution in the lower hemifield (He, Cavanagh, & Intriligator, 1996). Here we show that the upper/lower asymmetry in visual crowding can be explained by natural variations in the borders of each individual's visual field. Specifically, asymmetry in crowding along the vertical meridian can be almost entirely accounted for by replacing the conventional definition of visual field location, in units of degrees of visual angle, with a definition based on the ratio of the extents of an individual's upper and lower visual field. We also show that the upper/lower crowding asymmetry is eliminated when stimulus eccentricity is expressed in units of percentage of visual field extent but is present when the conventional measure of visual angle is used. We further demonstrate that the relationship between visual field extent and perceptual asymmetry is most evident when participants are able to focus their attention on the target location. These results reveal important influences of visual field boundaries on visual perception, even for visual field locations far from those boundaries.
authors.affiliation: Department of Psychology, University of California, Berkeley, CA, USA Department of Veterans Affairs, Martinez, CA, USA Present address: Department of Veterans Affairs, Boston Healthcare System, Boston, MA, USA.
authors.forename: Francesca C
authors.initials: FC
authors.lastname: Fortenbaugh
authors.affiliation: School of Optometry, University of California, Berkeley, CA, USA Vision Science Graduate Group, University of California, Berkeley, CA, USA Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Silver
authors.affiliation: Department of Psychology, University of California, Berkeley, CA, USA Department of Veterans Affairs, Martinez, CA, USA Vision Science Graduate Group, University of California, Berkeley, CA, USA Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Robertson
mesh_terms: D001288:Attention; D003441:Crowding; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D007802:Language; D008297:Male; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: attention; coordinate system; crowding; space perception; visual field extent; visual space