Heartfelt imitation: high interoceptive awareness is linked to greater automatic imitation.

'Interoceptive awareness', defined as the individual's awareness of internal body signals, modulates self/other distinction under conditions of multisensory integration. We examined here, for the first time, the potential impact of interoceptive awareness on self/other distinction in the motor domain. In automatic imitation, inhibition of imitation is an index of an individual's success in distinguishing internally generated motor representations from those triggered by observing another person's action. This is measured by the 'congruency effect', which is the difference between mean reaction times when the observed action is 'incongruent' with the required action and when it is 'congruent'. The present study compared the congruency effect in a typical finger lifting paradigm, with interoceptive awareness measured by heartbeat perception. Contrary to expectation, interoceptive awareness was positively correlated with the congruency effect and this effect depended on mean reaction times in the incongruent condition, indicating that good heartbeat perceivers had more difficulty inhibiting the tendency to imitate. Potentially, high interoceptive awareness involves stronger interoceptive representations of the consequences of an action, implying higher empathy, greater motor reactivity in response to observed action and hence a greater tendency to imitate. Our results may also tentatively be explained within a predictive coding account of interoception.