title: Behavioral Differences in the Upper and Lower Visual Hemifields in Shape and Motion Perception.
abstract: Perceptual accuracy is known to be influenced by stimuli location within the visual field. In particular, it seems to be enhanced in the lower visual hemifield (VH) for motion and space processing, and in the upper VH for object and face processing. The origins of such asymmetries are attributed to attentional biases across the visual field, and in the functional organization of the visual system. In this article, we tested content-dependent perceptual asymmetries in different regions of the visual field. Twenty-five healthy volunteers participated in this study. They performed three visual tests involving perception of shapes, orientation and motion, in the four quadrants of the visual field. The results of the visual tests showed that perceptual accuracy was better in the lower than in the upper visual field for motion perception, and better in the upper than in the lower visual field for shape perception. Orientation perception did not show any vertical bias. No difference was found when comparing right and left VHs. The functional organization of the visual system seems to indicate that the dorsal and the ventral visual streams, responsible for motion and shape perception, respectively, show a bias for the lower and upper VHs, respectively. Such a bias depends on the content of the visual information.
authors.affiliation: Gerontechnology and Rehabilitation Group, University of Bern Bern, Switzerland.
authors.forename: Giuseppe A
authors.initials: GA
authors.lastname: Zito
authors.affiliation: Gerontechnology and Rehabilitation Group, University of BernBern, Switzerland; ARTORG Center for Biomedical Engineering Research, University of BernBern, Switzerland.
authors.forename: Dario
authors.initials: D
authors.lastname: Cazzoli
authors.affiliation: Gerontechnology and Rehabilitation Group, University of BernBern, Switzerland; Division of Cognitive and Restorative Neurology, Department of Neurology, University Hospital Inselspital, University of BernBern, Switzerland.
authors.forename: René M
authors.initials: RM
authors.lastname: Müri
authors.affiliation: Gerontechnology and Rehabilitation Group, University of BernBern, Switzerland; Privatklinik WyssMünchenbuchsee, Switzerland; University Hospital of Old Age Psychiatry and Psychotherapy, University of BernBern, Switzerland.
authors.forename: Urs P
authors.initials: UP
authors.lastname: Mosimann
authors.affiliation: Gerontechnology and Rehabilitation Group, University of BernBern, Switzerland; University Hospital of Old Age Psychiatry and Psychotherapy, University of BernBern, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Nef
keywords: motion perception; perceptual asymmetries; shape perception; upper and lower hemifields; visual test