Interoception modulates fear detection in binocular onset rivalry

Interoception is the body-to-brain axis of sensation concerning the state of the internal body. Interoceptive signals from the heart can modulate emotional processing. Moreover, the degree to which people accurately detect their own heart beating at rest can predict their emotional responsivity. Here we determine how interoceptive signals can modulate the perception of faces by exploiting phasic cardiac activity within a binocular onset rivalry paradigm. We demonstrate that afferent cardiac signals facilitate the early processing of fearful face images in individuals with high interoceptive (heartbeat detection) accuracy: The contraction of heart at cardiac systole enhanced the detection of fearful faces (during initial image selection in rivalrous presentations), and shortened reaction times for subsequent emotional judgements. However, cardiac systole does not lead to an overall bias in increased fear categorisation. Our findings highlight interactive contributions of interoception in shaping perceptual and behavioural aspects of emotional processing. Our results thereby add to empirical data regarding mechanisms of body-brain integration underpinning emotional experience. (Preprint of manuscript under review)