Abstract
PURPOSE Grouping processes aid in the resolution of ambiguity that results from competing incompatible visual inputs. Can a grouping process act on representations from ambiguous objects when the ambiguity is created in different feature dimensions (e.g., only orientation or only chromaticity)? METHODS Two separate gratings were made ambiguous by binocular rivalry of two features, orientation and color, to determine if grouping processes can act across ambiguity created by different rivalrous features. Three observers viewed 1.5° dichoptic equiluminant chromatic square-wave 4-cpd gratings presented in interocular-switch rivalry, swapped at 3.75 Hz (Christiansen et al., JOV 2017). Each trial had two separate gratings, one above and one below fixation, with one of the gratings rivaling in only orientation (e.g., green-45° and green-135°) and the other in only chromaticity (e.g., green-45° and red-45°). Four percepts were measured: top and bottom gratings identical in only color (e.g., green-45° and green-135°), top and bottom gratings identical in only orientation (e.g., green-45° and red-45°), top and bottom gratings identical in both color and orientation (e.g., green-45° and green-45°), and top and bottom gratings different in both color and orientation (e.g., red-45° and green-135°). RESULTS All observers perceived gratings different in both color and orientation (e.g., green-45° and red-135°) more often than chance. They also perceived only identical orientation (e.g., green-45° and red-45°) more often than chance. Only one observer perceived gratings identical in color and orientation more often than chance. CONCLUSION These results suggest a disambiguating process that can enhance the difference between two ambiguous percepts. A difference-enhancing process, whereby the percepts of separate objects are resolved to be different in both features, may be an alternative to traditional grouping processes. Note that top and bottom gratings were consistently different in color more often than chance, suggesting that color disambiguation may enhance perceptual differences, rather than similarities.
Acknowledgement: Supported by NIH EY-026618