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Josephine Reuther, Ramakrishna Chakravarthi, Jasna Martinovic; Masking, crowding and grouping: studying low and mid-level vision in a diverse cohort using a common framework. Journal of Vision 2020;20(11):1209. doi: https://doi.org/10.1167/jov.20.11.1209.
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Whether visual information is individuated or texturized is susceptible to modulation at multiple processing levels. Commonly, low and mid-level visual processes are studied using disparate stimuli and tasks in a relatively small number of often well-trained observers. Here, we examine the dependencies in processing across multiple levels by investigating three phenomena (masking, crowding and grouping) that target these levels of processing within the same participants while using a common stimulus consisting of 9 Gabor elements. Contrast thresholds were assessed in more than 50 observers (age range: 20 to 70) for several inter-element distances in parafoveal (3.5 deg) and peripheral (7 and 10.5 deg) locations using a spatial two-alternative forced-choice procedure. The aim of the study is to build a unitary framework of low and mid-level vision and to assess the extent to which perceptive fields (masking), integration fields (crowding) and association fields (grouping) are co-dependent. Using tasks that incentivize participant behavior (integrate vs. individuate) in line with the phenomena of interest, we elicited signatures of masking, crowding and grouping. For all three phenomena we find that contrast thresholds were modulated by inter-element distance, with a shallower and inverted effect for grouping compared to masking and crowding. That is, the pattern of results was qualitatively similar for masking and crowding, but not for grouping. Inter-observer variability increased with eccentricity and with the putative size of the visual field upon which visual processing is reliant, with the highest variation at 10.5 degrees eccentricity for grouping.
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