Abstract
Grouping by similarity of a stimulus-level feature, such as chromaticity, can contribute to the perceptual resolution of multiple visually ambiguous objects (Wang & Shevell, VSS 2016). When two objects are presented with different degrees of ambiguity, the proportion of time the separate objects are grouped to give the same perceptual resolution is reduced compared to when both objects have the same degree of ambiguity (Grossman & Dobbins, 2003, Vision Research). The present study investigates whether the degree of ambiguity of an object is a stimulus-level feature itself that contributes to grouping and, if so, how it interacts with other stimulus features that contribute to grouping. Methods: Observers viewed multiple equiluminant chromatically-rivalrous discs that were exchanged between the eyes at 3.75Hz (i.e. in interocular switch rivalry) and reported whenever all discs were perceived to be a single color, either "red" or "green". These ambiguous chromatically-rivalrous discs could be presented together with unambiguous non-rivalrous colored discs. Up to 8 discs could be presented simultaneously, arrayed along a circular contour. Observers fixated at the circle's center. Five stimulus displays with different proportions of ambiguous and unambiguous discs were tested: 8 ambiguous discs, 7 ambiguous discs, 7 ambiguous discs with 1 unambiguous disc, 4 ambiguous discs with 4 unambiguous discs, and 4 ambiguous discs alone. Results/Conclusion: Including unambiguous colored discs reduced by 50% or more the time during which all discs were perceived to be the same color. This indicates that the stable unambiguous discs did not bias chromatic perceptual resolution of the rivalrous ambiguous discs. The proportion of ambiguous versus unambiguous discs had no significant effect. These results indicate that ambiguity itself is indeed a feature of an object used to group the objects so they are perceived to have a common color.
Meeting abstract presented at VSS 2018