Sensory reliability takes priority over the central tendency effect in temporal and spatial estimation

Perception is influenced by contextual factors that help resolve sensory uncertainty. A well-known phenomenon, the central tendency effect, describes how perceptual estimates gravitate toward the mean of a distribution of stimuli, particularly when sensory input is unreliable. However, in multisensory contexts, it remains unclear whether this effect follows a generalized priority across modalities or might be influenced by task-relevant sensory dominance. We studied spatial and temporal estimation in the auditory and visual modalities, testing whether perceptual estimates are driven by a supra-modal prior or by modality reliability specific to the task, and applied Bayesian modeling to explain the results. Participants first performed baseline sessions using only one modality and then a third session in which the modalities were interleaved. In the interleaved session, we found that the changes in auditory and visual estimates were not towards a supra-modal (generalized) prior, but estimates related to the dominant modality (vision for space, audition for time) were stable, while estimates of the other sensory modality (audition for space, vision for time) were pulled towards the dominant modality's prior. Bayesian modeling also confirmed that the best-fitting models were those in which priors were modality-specific rather than supra-modal. These results highlight that perceptual estimation favors sensory reliability over a general tendency to regress toward the mean, providing insights into how the brain integrates contextual information across modalities.