title: Modulated textures with shape structures implied by a closed flow are processed globally.
abstract: Radial frequency (RF) patterns, shapes deformed from circular by a sinusoidal modulation of radius, have been used to demonstrate global integration of shape information around a closed path by showing that the modulation depth required to detect shape deformation decreases rapidly as larger segments of the contour are modulated. In this psychophysical study we use a field of Gabor patches to examine integration of shape information in sampled RF patterns either alone or placed within an orientation-noise background and show that orientation-noise can be disregarded during the integration of modulation information. We also examine integration in modulated textures with local orientations that flow parallel or perpendicular to an underlying RF shape-structure. In using modulated textures comprising of elements with a random radial position but with orientation modulated such that it conforms to the local orientation of an RF pattern (RF texture) we demonstrate integration around texture patterns that imply shape. Texture patterns with element orientations locally orthogonal (RFO textures) to those of RF textures, however, exhibit a rate of decrease in modulation threshold, which is substantially reduced. When the textures are scrambled by permuting the polar positions of the patches the rate of decrease in threshold with increasing number of patches modulated in orientation is reduced for RF textures but not RFO textures. Detection of modulation in both scrambled textures is shown to be consistent with the detection of local cues. We conclude that implied closure in a modulated flow appears to be critical for global integration of textures.
authors: School of Psychology, University of Western Australia, Crawley, Western Australia, Australia.
authors: Ken W S
authors: KW
authors: Tan
authors: School of Psychology, University of Western Australia, Crawley, Western Australia, Australia.
authors: Vanessa K
authors: VK
authors: Bowden
authors: School of Psychology, University of Western Australia, Crawley, Western Australia, Australia.
authors: J Edwin
authors: JE
authors: Dickinson
authors: School of Psychology, University of Western Australia, Crawley, Western Australia, Australia.
authors: David R
authors: DR
authors: Badcock
mesh_terms: D003463:Cues; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D010364:Pattern Recognition, Visual / Q000502:physiology; D011601:Psychophysics
keywords: RF patterns; integration; radial frequency patterns; texture perception