Clockwise Bias in 2D Rotation: A Cognitive Rather Than Sensory Phenomenon

Abstract

Previous studies have documented a preference for clockwise (CW) over counterclockwise (CCW) rotation in various visual tasks, but the underlying mechanisms remain unclear. To determine at what stage the CW bias emerges, we tested this preference across multiple visual awareness paradigms using consistent 2D rotation stimuli. In Experiment 1, we found a strong CW bias in apparent motion, with CW dominating perception 1.6 times longer than CCW during long-term presentations and eliciting an average of 74% CW percepts in short-term presentations. By contrast, no CW bias was observed in binocular rivalry, suggesting its absence in low-level perceptual conflict. Experiment 2 employed the breaking continuous flash suppression (b-CFS) paradigm to assess unconscious preferences, revealing no difference in breakthrough times between CW and CCW rotations. Specifically, although apparent motion stimuli showed a higher frequency of CW percepts, breakthrough times for stimuli reported as CW and CCW were similar, indicating that the CW bias occurs after stimuli reach awareness. In Experiment 3, we manipulated the ambiguity of apparent motion stimuli and found significant interactions between the CW bias and input ambiguity, further ruling out a fixed sensory or response bias. These findings suggest that the CW bias in 2D rotation may be driven by higher-level cognitive processes, offering insights into how the visual system resolves perceptual ambiguity.