title: Competition and sharing of processing resources in visual discrimination.
abstract: Discrimination thresholds for spatial frequency and contrast tested individually were compared with dual discrimination of contrast and spatial frequency, and dual discrimination of 2 contrast or spatial frequency components. The components were presented overlapping, forming a compound grating or as side-by-side simple gratings. When observers had to judge contrast and spatial frequency simultaneously, discrimination thresholds increased by an amount predicted by a model of stimulus uncertainty for orthogonal dimensions (1.7); when they had to judge 2 frequency or contrast components, discrimination thresholds increased by a factor of 3-6 compared with the single-judgment task. The relative spatial location of the components did not interact with task complexity. The results are consistent with a model assuming a set of parallel special-purpose attentional mechanisms.
authors.affiliation: Department of Psychology, University of Oslo, Norway. svein.magnussen@psykologi.uio.no
authors.forename: S
authors.initials: S
authors.lastname: Magnussen
authors.forename: M W
authors.initials: MW
authors.lastname: Greenlee
mesh_terms: D000704:Analysis of Variance; D001288:Attention; D015350:Contrast Sensitivity; D006801:Humans; D016015:Logistic Models; D008960:Models, Psychological; D012684:Sensory Thresholds; D013028:Space Perception