title: Orientation discrimination for bars defined by orientation texture.
abstract: A texture pattern consisting of short (0.2 deg) lines contained a 5.0 deg x 1.4 deg texture-defined bar. The bar was rendered visible by the difference in orientation (2 theta) between the lines inside the bar and outside the bar. Orientation-discrimination threshold for the texture-defined bar was a U-shaped function of 2 theta over the range 2 theta = 0 degree to 2 theta = 180 degrees. The lowest threshold was at 2 theta = 90 degrees, and was 0.57 degrees for both subjects tested. This threshold was little different from the lowest values of threshold for motion-defined bars, disparity-defined bars, and colour-defined gratings reported elsewhere. A luminance-defined bar was created by switching off all texture lines outside the texture-defined bar. Orientation-discrimination threshold fell to a limiting value as the luminance contrast of this bar was progressively increased. The lowest value of orientation discrimination for the luminance-defined bar (0.42 degrees and 0.35 degrees for the two subjects) was not greatly less than the lowest value for the texture-defined bar.
authors.affiliation: Department of Psychology, York University, North York, Ontario, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Regan
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D015348:Vision, Binocular; D014792:Visual Acuity; D014796:Visual Perception