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Satoru Suzuki, Marcia Grabowecky; Rapid temporal coincidence of spatially separated shapes can be resolved using sustained emergent percepts. Journal of Vision 2001;1(3):56. doi: https://doi.org/10.1167/1.3.56.
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© ARVO (1962-2015); The Authors (2016-present)
In a rapidly changing display it is difficult to detect the temporal coincidence of objects, parts, or features across space. However, we discovered that under certain conditions rapid temporal coincidence can be resolved based on emergent percepts. These include perceptual stability, depth segregation, monocular rivalry, and a shimmering apparent motion, with the last two percepts persisting through very fast alternation rates. Observers were given unlimited time to decide which of two rapidly alternating images contained circular targets. The alternating images consisted of a pair of orthogonally-oriented luminance-defined single bars or square wave gratings (2 deg extent, with no ISI). Targets occurred at the intersection of bars where the two images had identical color and luminance. Consequently the task required rapid binding across space of the target and bar to determine which bar contained the target. Detection of coincidence was slow when the target was defined by equiluminous color (∼150 ms/frame) or when the target was presented only once (∼100 ms/frame). When the target was defined by both luminance and color performance improved and, under appropriate conditions, generated emergent percepts. When targets appeared with single bars (.7 deg wide) and had a diameter similar to the bar width, a shimmering apparent motion allowed reliable detection of the target-bar coincidence to alternation rates of 27 ms/frame. When gratings of midrange spatial frequency (4.5 cycles/deg) alternated, monocular rivalry (1–2 sec/orientation phase) became salient when alternation rates neared the fusion rate (∼40 to 67 ms/frame for stimulus contrasts used). This rivalry percept preserved information about the target-grating coincidence in this range of intervals. These results suggest that the visual system has temporal summation mechanisms that preserve rapid temporal coincidences in the form of sustained emergent percepts.
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