Background: Perceptual history plays an important role in sensory processing and decision making, shaping how we perceive and judge external objects and events. Indeed, past stimuli can bias what we are currently seeing in an attractive fashion, making a current stimulus appear more similar to a preceding one than it actually is. Such attractive "serial dependence" effects concern virtually every aspect of perception, suggesting that they may reflect a fundamental principle of brain processing. However, it is unclear whether the ubiquitous nature of serial dependence is due to an underlying centralised mechanism, or to the existence of separate mechanisms implemented independently in different perceptual pathways. Here we address this question by assessing the behavioural and neural signature of serial dependence in the auditory and visual sensory modality (in separate conditions), in the context of time perception. Results: Our results first show a double dissociation between the two modalities, whereby auditory serial dependence is selective for the features of the stimuli (i.e. reduced effect when successive stimuli have different features) but not their position, and vice versa in vision. Electroencephalography results further support a difference between the visual and auditory modality, demonstrating that the signature of serial dependence unfolds according to different dynamics in the two modalities. Conclusions: Overall, our results suggest that the serial dependence effect is mediated by different and at least partially independent modality-specific mechanisms, potentially based on the same computational principle implemented in different sensory pathways.
