Respiration–action coupling and intentional binding in a Libet clock paradigm

Abstract Interoception, the physiological sensing of internal bodily states, has been proposed to contribute to the sense of self. However, empirical research that directly investigates interoceptive contributions to the sense of agency remains limited. Based on the observed synchronisation between respiratory phase and the initiation of voluntary action, we implemented the Libet clock task to test the hypothesis that the respiratory phase would modulate intentional binding (IB), a temporal binding phenomenon often used as an implicit measure related to agency. Additionally, we aimed to replicate respiration–action synchronisation and to examine exploratory cardiac-phase effects on binding. The overall key-binding effect was small and did not reach statistical significance, whereas tone binding was significant. Neither key nor tone binding showed reliable respiratory-phase modulation, although respiration–action synchronisation was replicated. Bayesian model comparisons strongly favoured models in which binding did not vary with respiratory phase. For cardiac phase, a frequentist mixed-effects model suggested phase-dependent modulation of key binding, but Bayesian model comparison did not support including cardiac-phase interactions. Together, these findings show that respiration–action coupling was present in the task but was not accompanied by detectable respiratory-phase modulation of intentional binding; the cardiac finding should be considered exploratory.