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Jan Skerswetat, Monika Formankiewicz, Sarah Waugh; Testing Levelt's laws for interocular grouping using contrast- and luminance-modulated stimuli. Journal of Vision 2018;18(10):446. doi: 10.1167/18.10.446.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual rivalry or grouping can arise when different stimuli are presented to the two eyes. We initiated interocular grouping (IOG) using orthogonally oriented split-gratings for which complementary halves were of the same stimulus type. Stimulus types were luminance-modulated (LM) or contrast-modulated (CM) noise gratings. Levelt's modified laws (Brascamp et al. 2015) were tested for IOG using these stimuli. Estimates of multiples above contrast detection threshold served as a measure for the visibility of each stimulus component. A stimulus presented to one eye (with the two orientations) could have been all LM (LMvsLM) or included LM and CM types (LMvsCM). The gratings had a spatial frequency of 2/deg and a diameter of 2deg. The noise was interocularly correlated and had an amplitude of 0.2. To test the first three laws, the CM component was always 7x visibility and the LM visibility was one of 3.5, 7, or 44x. To test the fourth law, the visibility of the whole stimulus in both eyes was either 3.5 or 7x (LMvsCM and LMvsLM) and 44x (LMvsLM). Nine participants with normal binocular vision indicated whether a horizontal, vertical, piecemeal, or superimposed percept was seen. The results for the LMvsLM condition tended to follow the predictions based on Levelt's modified laws, whereas the results for the LMvsCM condition tended not to. These results are similar to findings from a previous investigation using conventional binocular rivalry with full CM and LM gratings (Skerswetat et al. 2016, VSS poster). Our findings suggest that conventional binocular rivalry and IOG with LM stimuli are processed differently compared to when both stimulus types are used.
Meeting abstract presented at VSS 2018
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