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Philip Kellman, Gennady Erlikhman, Susan Carrigan; Is There a Common Mechanism for Path Integration and Illusory Contour Formation?. Journal of Vision 2016;16(12):311. doi: 10.1167/16.12.311.
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"Path integration" refers to the perceptual grouping of oriented elements embedded in a field of randomly arranged elements. Pop-out of a path of Gabor elements is not accompanied by the perception of illusory contours connecting the elements. The relation of path integration to contour interpolation, as in illusory and occluded contours, has remained unclear. Some theories (Grossberg & Mingolla, 1985; Kellman, Guttman & Wickens, 2001) posit an early, "promiscuous" contour-linking stage of processing, resulting in an intermediate representation; further constraints (e.g., presence or absence of homogeneous surface characteristics within and between elements) determine whether visible contours appear in final scene representations. We hypothesize that path detection reveals this intermediate representation that is shared with contour interpolation. Consistent with this idea, altering Gabor elements so that their centers match the background produces clear illusory contours connecting the elements in the path. We tested the connection between path integration and contour perception in a series of objective performance and subjective rating experiments, using standard Gabor elements and modified elements with centers matching the background that supported illusory contours along paths. Participants searched for targets composed of elements that were either perfectly aligned or misaligned by varying degrees in a standard 2IFC path detection paradigm. The results reveal a clear correspondence between the two kinds of displays: path detection performance decreased as a function of degree of misalignment, and was indistinguishable for the two path types. Both sets of results confirmed earlier findings that illusory and occluded contour interpolation break down at about 15-20 arc min of retinal misalignment (Kellman & Shipley, 1991). Subjective ratings of perceived illusory contours as a function of misalignment, for the modified element displays, mirrored the path detection results. These results suggest that path integration reflects the earlier stage of a common contour-linking and contour interpolation mechanism.
Meeting abstract presented at VSS 2016
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