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 integrating information over successive moments. 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 employed 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. This result highlights the critical role of presentation format in cross-modal serial dependence. Furthermore, this effect was still observed when inducer stimuli was presented at different spatial positions, in contrast to previous studies on serial dependence within the visual modality. These findings suggest the involvement of a higher-level processing stage. Specifically, a representation that is not selective to specific modality or strictly tied to spatial position, although it remains selective to presentation format, may be involved in the observed effect.