Words under the skin: Physiological responses to interoceptive metaphors

Embodied accounts of language propose that linguistic meaning is grounded in sensorimotor systems. While previous research has focused on the central nervous system, the involvement of the autonomic nervous system (ANS) in language comprehension remains underexplored. To fill this gap, we investigated whether processing interoceptive metaphors, namely figurative expressions referring to internal bodily sensations (e.g., 'I feel butterflies in my stomach'), modulates the ANS. Forty-five healthy participants read interoceptive metaphors and non-bodily-related literal sentences while cardiac, electrodermal, and respiratory signals were continuously recorded. We further distinguished between two types of interoceptive metaphors, depending on whether the interoceptive element served as the target (INT-target, e.g., 'I feel butterflies in my stomach') or source domain (INT-source, e.g., 'I thirst for success' to convey ambition) of the metaphor. Results revealed subtle but measurable effects: compared to non-bodily-related literal sentences, interoceptive metaphors were associated with higher heart rate variability and longer inspiratory duration. No significant differences emerged between INT-target and INT-source metaphors. These findings provide the first evidence that language grounded in internal bodily experience is associated with subtle differences in selected autonomic indices relative to non-bodily-related literal sentences.