title: Hemispheric differences in visual search of simple line arrays.
abstract: The effects of perceptual organization on hemispheric visual-information processing were assessed with stimulus arrays composed of short lines arranged in columns. A visual-search task was employed in which subjects judged whether all the lines were vertical (same) or whether a single horizontal line was present (different). Stimulus-display organization was manipulated in two experiments by variation of line density, linear organization, and array size. In general, left-visual-field/right-hemisphere presentations demonstrated more rapid and accurate responses when the display was perceived as a whole. Right-visual-field/left-hemisphere superiorities were observed when the display organization coerced assessment of individual array elements because the physical qualities of the stimulus did not effect a gestalt whole. Response times increased somewhat with increases in array size, although these effects interacted with other stimulus variables. Error rates tended to follow the reaction-time patterns. The results suggest that laterality differences in visual search are governed by stimulus properties which contribute to, or inhibit, the perception of a display as a gestalt. The implications of these findings for theoretical interpretations of hemispheric specialization are discussed.
authors.affiliation: Department of Neuropharmacology, Research Institute of Scripps Clinic, La Jolla, CA 92037.
authors.forename: J
authors.initials: J
authors.lastname: Polich
authors.forename: D P
authors.initials: DP
authors.lastname: DeFrancesco
authors.forename: J F
authors.initials: JF
authors.lastname: Garon
authors.forename: W
authors.initials: W
authors.lastname: Cohen
mesh_terms: D000328:Adult; D001288:Attention; D004193:Discrimination Learning; D004292:Dominance, Cerebral; D005556:Form Perception; D006801:Humans; D008297:Male; D009949:Orientation; D010364:Pattern Recognition, Visual; D011930:Reaction Time