Distinct perceptual-metacognitive profiles of interoceptive and exteroceptive timing

Time perception is fundamental to human behavior and decision-making, yet its underlying processes remain debated. Interoception and exteroception, as channels of internal bodily and external environmental information, are both implicated in shaping duration perception, but their respective contributions have rarely been directly compared. Here, we employed a dual-task paradigm combining a heartbeat discrimination task with interval production to systematically contrast the effects of interoceptive and exteroceptive processing on timing accuracy and precision. Results revealed distinct patterns between the two channels: although interoceptive and exteroceptive timing showed comparable accuracy, the factors supporting this accuracy differed, with interoceptive perceptual accuracy linked to both perceptual and metacognitive indicators, whereas exteroceptive perceptual accuracy was not predicted by either. By contrast, the two channels diverged in temporal precision, with interoceptive timing becoming more precise at longer intervals and shaped by both metacognitive and perceptual indicators, while exteroceptive precision depended primarily on perceptual performance. These findings suggest that the brain achieves similar behavioral outcomes while relying on different patterns of perceptual and metacognitive involvement optimized for channels with different signal-to-noise profiles, consistent with predictive coding accounts. Future research should investigate the neural and computational bases of these partially separable mechanisms.