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Sharon Guttman; Grouping by similarity and temporal structure: Evidence for a common mechanism. Journal of Vision 2012;12(9):1297. doi: 10.1167/12.9.1297.
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© ARVO (1962-2015); The Authors (2016-present)
What neural mechanisms signal the binding of local image features into global spatial forms? Numerous studies indicate that temporally correlated image changes promote visual grouping, prompting the suggestion that neural synchrony plays a role in binding. However, evidence for the involvement of a similar mechanism for grouping based on non-temporal cues remains limited. In the current study, observers viewed arrays of Gabor patches changing stochastically in spatial frequency. Elements within a central rectangular region changed according to one point process whereas all remaining patches changed according to a second point process, giving rise to a figure defined by temporal structure (TS). On some trials, a similarity cue complemented the TS-defined rectangle: "figure" Gabor patches shared one orientation, whereas "ground" patches shared the orthogonal orientation. On other trials, this similarity cue opposed the TS-defined rectangle: the orientations of the Gabor patches suggested a horizontal rectangle whereas TS suggested a vertical rectangle, or vice versa. In a third condition, the similarity cue was absent: orientations of the Gabor patches were randomly arranged within the array. In all cases, observers’ judged the orientation of the rectangle defined by temporal structure. The results suggest that although temporal structure provided a strong basis for grouping—observers accurately identified the orientation of the TS-defined rectangle when the similarity cue was absent or complementary—accurate temporal judgments could not be made in the presence of a conflicting similarity cue, especially as the strength of the temporal cue decreased. These results are consistent with the notion that elements grouped by similarity trigger temporally correlated neural responses, negating the ability to make competing judgments about temporally cued grouping. These findings will be discussed in the context of ongoing debates regarding the role of neural synchrony in the binding of local features into coherent global forms.
Meeting abstract presented at VSS 2012
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