Abstract
Previous studies reported idiosyncratic preferences in binocular rivalry during the onset stage (Carter & Cavanagh, 2007; Stanley, Carter, & Forte, 2011). Meanwhile, other studies revealed that there are idiosyncratic preferences to perceive certain motion directions in front during motion transparency depth rivalry (Mamassian & Wallace, 2010; Schütz, 2014). These directional preferences appear to be a fast process that relies on early, 1D motion signals (Schütz & Mamassian, 2016), but it is not clear if they originate at a monocular or binocular processing stage. Here we investigate the relationship of idiosyncratic preferences in motion transparency and binocular rivalry. We presented two overlapping dot clouds that were moving in opposite directions and had opposite contrast polarity (black vs. white). Across trials, the motion direction of the black cloud was varied in 15° steps (24 possible directions). Participants performed two consecutive experimental phases. In the transparent motion phase, both dot clouds were presented to both eyes and participants had to report the color of the dot cloud they perceived in front. In the binocular rivalry phase, the dot clouds were presented to different eyes and participants had to report the color of the dominant dot cloud. We calculated individual preferences for contrast polarity and motion direction separately for each experimental phase. Replicating previous findings, there were strong idiosyncratic directional preferences in transparent motion and rather weak preferences for contrast polarity. The results were reversed in binocular rivalry, showing weak preferences for motion direction but strong preferences for contrast polarity. These findings show that idiosyncratic preferences in a visual feature can be dissociated at different stages of processing. The weak directional preferences in binocular rivalry are in stark contrast to findings from other types of ambiguous stimuli and suggest that the directional preferences in transparent motion arise at a binocular processing stage.
Meeting abstract presented at VSS 2018