title: Contextual influences in texture-segmentation: distinct effects from elements along the edge and in the texture-region.
abstract: Both neurophysiological and psychophysical evidence suggest a strong influence of context on texture-segmentation. Here we extend and further analyse this issue, with a particular focus on the underlying mechanism. Specifically, we use a texture-edge discrimination task and separately investigate the effect of elements far from and along the edge. Consistent with previous studies, we report both an iso-near contextual effect - whereby performance is better if elements along the edge are iso-oriented compared to ortho-oriented to the edge - as well as an ortho-far effect - whereby discrimination is higher when elements far from the edge are orthogonal to the edge. We found that backward mask, which is known to interrupt re-entrant processing from extrastriate areas, only interferes with the iso-near effect whereas perturbing orientation, position or contrast polarity of elements far from the edge only abolishes the ortho-far effect. This suggests that feedback processes may be involved in the iso-near effect. Instead, the ortho-far effect may be accounted for by recurrent interactions among 1st order filters.
authors.affiliation: Department of General Psychology, University of Padua, Via Venezia 8, 35131 Padua, Italy. valentina.robol@unipd.it
authors.forename: Valentina
authors.initials: V
authors.lastname: Robol
authors.forename: Massimo
authors.initials: M
authors.lastname: Grassi
authors.forename: Clara
authors.initials: C
authors.lastname: Casco
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004192:Discrimination, Psychological; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology
keywords: Backward mask; Contextual influences; Recurrent interactions; Texture-segmentation