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Barbara Dosher, Shiau-Hua Liu, Nathaniel Blair, Zhong-Lin Lu; The spatial footprint of the perceptual template. Journal of Vision 2003;3(9):562. doi: 10.1167/3.9.562.
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© ARVO (1962-2015); The Authors (2016-present)
Visual stimulus discrimination or identification requires input from and weighting of information presented in spatial regions incorporating the signal stimulus. In this study, we evaluate the spatial “footprint” of information integration in Gabor orientation identification by evaluating the impact of high contrast external noise in different spatial sub-regions of the display. From prior studies of spatial attention, it is known that external noise masking is primarily effective in the region of the target stimulus and not other masked regions in the display (1); what is not known is the distribution of relevance within the target region. We divided the spatial region in and around the neighborhood of the Gabor (standard deviation of the spatial window of 12 pixels) into four concentric rings (demarked by radii of 12, 17, 21, or 24 pixels incorporating an approximately equal number of pixels into successive rings) and measured the psychometric functions for orientation discrimination (top far left, near left, near right, and far right) in the presence of different combinations of external random Gaussian noise rings (e.g., R1 alone; R1+R2; etc.). If a spatial region has non-zero weight in the perceptual template for discrimination, then noise in that region should have little or no effect on performance. In both fovea and attended periphery, effective noise regions aligned fairly closely with the presence of the signal in the Gabor patches — the template “shrink wrapped” the informative stimulus region. There was also evidence supporting some implementation of adaptive and selective input weighting of different spatial regions. However, in unattended periphery, the perceptual template was less selective. (1) Lu, Lesmes, & Dosher, JOV, 2002.
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