Cardiac Influences on Bistable Perception in the Auditory System

Auditory perception has traditionally been understood as the passive encoding of acoustic energy from the external environment. However, recent research suggests that internal bodily signals, particularly cardiac signals, may also influence how external auditory information is organized in the brain. The present study examined whether the cardiac cycle has a role in modulating auditory stream segregation, a bistable auditory phenomenon. Twenty participants listened to sequences of tones (ABA- triplet), with the timing of the B tone synchronized to either cardiac systole or diastole. Results from the mixed-effects logistic regression showed that stimuli presented during cardiac systole were more likely to be perceived as two separate streams. Notably, this effect did not depend on whether participants could consciously perceive their own heartbeat, suggesting that interoceptive signals are unconscious when modulating the auditory percept. This finding challenges the traditional baroreceptor view that baroreceptors would inhibit sensory processing during cardiac systole. It supports that interoceptive signals dynamically shape perceptual processes. The evidence that cardiac signals influence perception extends from the visual to the auditory domain, suggesting a broad role for interoceptive signals in multisensory information processing.