HOYEON YOON¹ (), JONGMIN MOON², OH-SANG KWON¹; ¹Ulsan national institute of science and technology, ²The University of Texas at Austin

Despite numerous studies on serial dependence in visual perception, the locus of the serial dependence within the perceptual process remains unclear. Moon and Kwon (2022) proposed that repulsive serial dependence occurs at an early encoding stage, while attractive serial dependence arises at a later estimation stage of visual processing. This hypothesis was based on their finding that the estimation of the current stimulus is repelled away from the previous stimulus but attracted toward the previous response. In contrast, Cicchini et al. (2021) demonstrated that attractive serial dependence occurs prior to surround tilt illusion, suggesting that attractive serial dependence occurs at an early stage of processing. Here, we investigated serial dependence using a motion repulsion stimulus, in which two directions of random dot motion move transparently. Motion repulsion exaggerates the perceived difference between adjacent motions and is known to occur at an early stage of motion processing (Grunewald, 2004). To distinguish the two sets of random dots, we used color. On each trial, participants were informed of the target color before stimulus presentation and were asked to report the motion direction of the target. A total of 14 participants completed 1533 trials. As expected, we observed robust motion repulsion and attractive serial dependence. More importantly, we tested whether serial dependence occurs before or after motion repulsion. This was achieved by examining whether the center of serial dependence depends on the magnitude of motion repulsion across participants and conditions. Statistically significant positive correlations (r=0.2878, p=0.0157) were found between the magnitude of motion repulsion and the pattern of serial dependence, indicating that serial dependence occurs after motion repulsion. These results align with the hypothesis that repulsive serial dependence reflects efficient coding at early stages, while attractive serial dependence reflects perceptual inference at later stages of visual processing (Moon & Kwon, 2022).

Acknowledgements: This work was supported by National Research Foundation of Korea: [Grant Number NRF-2020S1A3A2A02097375]