Serial dependence in numerosity perception generalizes across different sensory modalities: evidence from sequential numerosity comparison

Serial dependence is a phenomenon in which current perception is attracted to the immediately preceding perception and is thought to reflect a mechanism for stabilizing perception by using autocorrelation in the world. It has been demonstrated across a variety of stimuli and has also been observed in the numerosity perception. A previous study suggested that cross-modal serial dependence in numerosity perception from audition to vision did not occur. However, differences in the stimulus presentation format might have prevented serial dependence from emerging. Therefore, we used a standardized temporal presentation format consisting of sequences of white noise and visual flashes. As a result, we observed bidirectional cross-modal serial dependence between audition and vision. The effects in each direction were not consistent within individuals. Furthermore, our investigation revealed no evidence for spatial selectivity in the observed cross-modal effects, despite previous studies on serial dependence within the visual modality confirming such spatial selectivity. These findings provide important insights into the mechanisms underlying serial dependence. It is suggested that both higher-level processing, such as abstract numerical representation, and lower-level processing, such as auditory and visual cortex involvement, are engaged in cross-modal serial dependence in numerosity perception. Moreover, our results align with predictive coding models, in which serial dependence arises when a prior generated at higher-level processing stages is fed back to lower-level sensory processing.