Heart beat interoception: a study of individual differences.

There were two principal aims of the study: to carry out preliminary evaluation of a novel heartbeat tracking technique for objectively measuring cardiac interoception; and to determine whether good and poor heartbeat perceivers could be differentiated with respect to other parameters reflecting individual differences in emotionality, including gender and 'emotional character'. Subjects first completed a battery of self-report questionnaires designed to measure characteristics of emotional experience, and then underwent a series of heartbeat tracking trials in which they used the index finger to tap in synchrony with their ongoing heartbeat activity (interoceptive tracking) and also with an audiotape of pre-recorded heartbeat sounds (exteroceptive tracking). The perceptual index was based on the variability of beat to tap latency. Concurrent validity findings suggested that the tracking index reflects a promising measure of cardiac interoceptive acuity. Good perceivers were found to have higher heart-rate measures than poor perceivers. With regard to 'emotional character' good perceivers had higher state anxiety, and were less emotionally expressive, although these differences were only marginally significant (P less than 0.08) with multivariate testing. Applications of the heartbeat tracking technique for further empirical evaluation of the role of interoception in emotion are discussed.