Bodily context sharpens visuotactile synchrony perception through causal inference

To maintain stable representations of both the bodily self and the external world, the brain must infer whether sensory signals arise from the same source or from different objects and events. Temporal synchrony provides a critical cue for this inference, but it remains unclear whether the bodily self constitutes a privileged perceptual context that systematically modulates multisensory integration beyond what is observed for external objects. Here, we investigated how bodily context and sensory uncertainty influence visuotactile synchrony perception. Participants viewed a rubber hand being tapped by a robot while receiving precisely timed tactile stimulation on their real hidden hand and judged whether the touches were synchronous. Asynchronies between seen and felt touches ranged from ±100 ms to ±400 ms. Critically, the rubber hand was either aligned with their real hand (bodily context) or rotated 180° (nonbodily context), and visual noise was manipulated to vary sensory reliability. Psychophysical and signal-detection analyses revealed that synchrony detection depended on asynchrony, rubber hand orientation, and visual noise: participants were more sensitive to asynchrony when the hand was aligned and when visual noise was low. A comparison of alternative computational models revealed that Bayesian causal-inference models incorporating both sensory uncertainty and bodily context best explained these effects, revealing that the two cues jointly shaped the decision criterion. These results demonstrate that the bodily context sharpens temporal multisensory sensitivity and that this sharpening is mechanistically accounted for by shifts in the causal-inference process in the bodily context.