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Local versus global contrasts in texture segregation

In a texture pair (TP) yielding a vertical or horizontal edge, the local (luminance or color) contrast or the local orientation of the individual textels is traded off with the global strength of the luminance-, color-, or orientation-defined TP edge so as to keep the latter at the detection threshold. Local and global contrasts are defined along within-domain or transdomain conditions; in the latter case local luminance or color contrast is traded off against global orientation. Textels differ from the background in either luminance or color so that the TPs are respectively equichromatic or equiluminant. TP edge strength is modulated by means of swapping variable proportions of textels between the 2 textures in the TP. Local-global relationships are fitted with a version of the equivalent noise model for contrast coding modified to include the presentation time factor. The extension of the standard model in the time domain is meant to allow comparison between equivalent noise estimates for variable duration stimuli. Model fits of the within-domain data yield equivalent noise energy values significantly different for color- and luminance-defined TPs but are not applicable for the transdomain experiments. (PsycINFO Database Record (c) 2005 APA, all rights reserved)



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