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Within‐texture alignment improves human texture segmentation
Author(s) -
Harrison S. J.,
Keeble D. R. T.
Publication year - 2002
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.2002.00086_32.x
Subject(s) - collinearity , texture (cosmology) , artificial intelligence , pattern recognition (psychology) , computer science , mathematics , offset (computer science) , psychophysics , spatial frequency , orientation (vector space) , computer vision , perception , optics , statistics , psychology , physics , geometry , neuroscience , image (mathematics) , programming language
Purpose: Spatial arrangement has been shown to be a critical factor both in detection facilitation of a threshold target by collinear flankers and in detection of smooth chains within random arrays of suprathreshold elements. Here, we investigate the effect of alignment between texture elements on human texture perception. Methods: Texture displays, consisting of arrays of elements, were presented to observers for 100 ms. Trials were completed with both line elements and with Gabor patches. A discrimination task consisted of one stimulus presentation, and observers distinguished between two possible orthogonal orientations of a central block, which differed from the surround by the orientation of its elements. A detection task required observers to indicate in which of two presentations the central block was present. For both tasks, the degree of alignment within stimuli was varied either by increasing orthogonal offset between elements or by decreasing the length of chains of aligned elements. Both alterations result in an overall reduction of collinearity within the display. A close‐spaced and a far‐spaced condition were tested. Global element density was kept constant within all line trials and within all Gabor trials. Results: For nearly all conditions, alignment was found to improve thresholds. The effect was robust to orientational jitter up to a standard deviation of the array‐element population of 8°. Conclusions: Our results suggest that collinearity between elements results in both short and long‐range interactions, which contribute to the formation of a texture‐defined surface. Interactions between close‐spaced elements might be explicable in terms of a linear‐filter summation paradigm, but results for far‐spaced elements would definitely require additional mechanisms.