Abstract
This study investigated how color and motion are integrated during binocular rivalry, by taking advantage of previous findings that binocular preceding stimuli phenomenally suppress one of the rivalrous stimuli having the same stimulus feature (e.g., Abe et al., VSS2010). Specifically, using moving chromatic gratings, this study examined how the preceding stimulus sharing color and/or motion with rivalrous stimuli modulated subsequent rivalry resolution. Rivalrous test stimuli were green-black rightward-moving vs. red-black leftward-moving gratings (540 msec). The preceding stimulus (1080 msec) corresponded to one of the rivalrous stimuli under the same-combination condition, whereas color and moving direction were combined differently under the different-combination condition (i.e., it was either green leftward-moving or red rightward-moving gratings). The results showed that modulative effects of the preceding stimulus produced exclusive dominance on most of the trials (>75%) under the same-combination condition; i.e., one of the rivalrous stimuli having different features from the preceding stimulus became dominant. Furthermore, very frequent misbinding of color and motion (about 60% of trials) were found under the different-combination condition. The misbound percept consisted of the features opposite to those in the preceding stimulus; e.g., a green leftward-moving preceding stimulus induced the percept of a red rightward-moving grating during subsequent rivalry, although the actual rivalrous stimuli were green rightward-moving and red leftward-moving gratings. These results suggested that color rivalry was resolved independently of motion rivalry. However, when the preceding stimulus was either achromatic moving gratings or static chromatic gratings, which shared only motion or color with the rivalrous stimuli, exclusive dominance was predominant (about 60% of trials) and misbinding occurred infrequently (<15%). Thus, color and motion were more associated under these conditions. Taken together, the present results indicated that although color and motion rivalry can be resolved independently, additional conditions need to be met for color and motion to be dissociated.