The following is a summary of “Masking, crowding, and grouping: Connecting low and mid-level vision,” published in the February 2022 issue of Ophthalmology by Reuther, et al.
For a study, researchers sought to investigate the similarities and differences among masking, crowding, and grouping, which are spatial interactions between neighboring elements, and to create a unified framework for low- and mid-level vision.
Using a common stimulus grid consisting of nine Gabor elements, contrast thresholds for Gabor detection, discrimination, and contour integration were measured as a function of inter-element spacing and eccentricity. The baseline contrast required to perform each task and the spatial extent over which task performance was stable were calculated from these thresholds. The spatial window was used to identify the field size, where elements within a potential field are readily combined.
The results showed that inter-element distance modulated contrast thresholds universally, with a shallower and inverted effect for grouping than for masking and crowding. Furthermore, the baseline contrasts required to detect and discriminate stimuli were positively correlated across retinal locations, while those required for integrating elements and discriminating their properties were negatively correlated. The spatial windows for masking and crowding remained uncorrelated across eccentricity but were correlated across participants, suggesting that the computation performed by each type of visual field operates over different distances that co-vary across observers but not across retinal locations.
Therefore, contrast-processing units may be at the core of the shared idiosyncrasies across tasks reported in previous studies, despite the fundamental differences in the extent of their spatial windows.