The features that control discrimination of an isodipole texture pair. (May 2019)

• Record Type: Journal Article
• Authors: Groulx, Kier; Chubb, Charles; Victor, Jonathan D.; Conte, Mary M.
• Is Part Of: Vision research. Volume 158(2019)
• Page Start: 208
• Page End: 220
• Publication Date: 2019-05
• Subjects: Isodipole texture -- Centroid method -- Preattentive vision; Vision -- Periodicals; 573.88
• DOI: 10.1016/j.visres.2019.03.006
• Languages: English
• ISSNs: 0042-6989

Abstract

Abstract: Visual features such as edges and corners are carried by high-order statistics. Previous analysis of discrimination of isodipole textures, which isolate specific high-order statistics, demonstrates visual sensitivity to these statistics but stops short of analyzing the underlying computations. Here we use a new texture centroid paradigm to probe these computations. We focus on two canonical isodipole textures, the even and odd textures: any 2 × 2 block of even (odd) texture contains an even (odd) number of black (and white) checks. Each stimulus comprised a spatially random array of black-and-white texture-disks (background = mean gray) that varied in their fourth-order statistics. In the Even (Odd) condition, disks varied along the continuum between random coinflip texture and pure (highly structured) even (odd) target texture. The task was to mouse-click the centroid of the disk array, weighting each disk location by the target structure level of the disk-texture (ranging from 0 for coinflip to 1 for even or odd). For each of block-sizes S = 2 × 2, 2 × 3, 2 × 4 and 3 × 3, a linear model was used to estimate the weight exerted on the subject's responses by the differently patterned blocks of size S . Only the results with 2 × 4 and 3 × 3 blocks were consistent with the data. In the Even condition, homogeneous blocks exerted the most weight; in the odd condition, block-pattern symmetry was important. These findings show that visual mechanisms sensitive to four-point correlations do not compute evenness or oddness per se, but rather are activated selectively by features whose frequency varies across isodipole textures.