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Chien-Chung Chen, Lee Lin, Yih-Shiuan Lin; Estimating the relative strength of similarity and proximity in perceptual grouping with tripole Glass patterns. Journal of Vision 2017;17(10):165. doi: https://doi.org/10.1167/17.10.165.
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© ARVO (1962-2015); The Authors (2016-present)
In Gestalt tradition, proximity and similarity are important cues for perceptual organization. We investigated how the visual system integrates these cues by measuring their relative strength when they produced conflicting grouping signals. We used tripole Glass pattern (tGP) which composed of randomly distributed sets of three dots, including a seed and two context dots. The tripoles were arranged in a way that linking the seed with one context dot would produce a percept of clockwise (CW) spiral while the other, counter-clockwise (CCW) spiral. The contrast of context ranged from -30 to 0dB while the seed contrast kept at -20dB. The distance between the seed and the context dots were between 5 and 20 min. The observers' task was to indicate whether the tGP they perceived in each trial was CW or CCW. When the distance between the seed and the two context dots were the same, the probability of seeing CW spiral first increased and then decreased with CW dot contrast, forming an Inverted-U shape psychometric function. The peak of the inverted-U function shifted rightward as CCW dot contrast increased. When all dots had the same contrast, it was 10-20% more likely to see the pattern formed by linking seed and the context dot at a half distance than the other dot. Such proximity advantage was canceled by decreasing the contrast of the proximity dot by about 6dB (50%), suggesting a linear trade-off between proximity and contrast similarity. Our result cannot be accounted for either by similarity or contrast energy theories for Glass pattern, but was well fit by a pattern normalization model, in which the response of a pattern detector was the sum of the excitations of linear filters operating on local dipoles raised by a power and divided by an inhibition signals from all other dipoles.
Meeting abstract presented at VSS 2017
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