Fine Tuning Your Heart: a novel method for measuring interoceptive accuracy

Interoception research is hampered by the lack of an agreed gold standard test of interoceptive accuracy. To avoid several confounds of heartbeat perception tasks, we devised a novel method of ‘heartbeat matching’, whereby participants use a custom-made slider to adjust the rate at which a heart icon is pulsing on a PC screen, to match this to the pace of their own heart. Because heartbeat counting has been shown to modulate with posture, participants completed both heartbeat matching and a standard heartbeat counting task while standing and when lying down. Accuracy was significantly higher in the heartbeat matching task. Moreover, ability to estimate elapsed time was also more accurate using the matching task but was not significantly correlated with interoceptive accuracy. Participants were more accurate on both tasks when lying down. However, participants underestimated the pace of their hearts in both methods. We discuss possible interpretations and how these might be distinguished.