Abstract
Although visual input is noisy and unreliable, we can perceive the identities of objects as stable and continuous. The mechanism contributing to this perceptual stability is called serial dependence, and it has been reported that the perception of stimulus features are assimilated toward stimuli presented in previous trials. Whereas the serial dependence has been reported for a variety of stimuli, the underlying mechanism remains unclear. In a previous study, we examined the correlation between individual differences in perceptual serial dependence for orientation and working memory capacity in order to determine whether serial dependence requires working memory, but no significant correlation was found between them across subjects (Zhang and Whitney, VSS2017). Here, we investigated the spatial tuning of perceptual serial dependence by examining whether the individual differences in orientation serial dependence are distinct for foveal and peripheral vision. In addition, we also examined serial dependence for orientation over two different days for the same subjects to confirm the stability of perceptual serial dependence. On each trial, subjects viewed Gabor patches and reported the perceived orientation of each Gabor by adjusting the orientation of a bar. For each subject, the Gabor's position was in the foveal or peripheral (10° eccentricity) visual field on both days or changed from day to day. The results showed that the assimilation effect toward the 1-back trial was significantly correlated in both foveal (r=.76) and peripheral vision (r=.77), even though they were measured on different days. Interestingly, these high within-subject correlations were also found when the assimilation effect was examined with foveal and peripheral vision on different days (r=.71). These results suggest that visual serial dependence is not mediated by separate systems in foveal and peripheral vision, but by a continuity field operator with broad spatial tuning that could facilitate perceptual stability of orientation information over time.