Knowledge of resting heart rate mediates the relationship between intelligence and the heartbeat counting task.

Evidence suggests that intelligence is positively associated with performance on the heartbeat counting task (HCT). The HCT is often employed as measure of interoception - the ability to perceive the internal state of one's body - however it's use remains controversial as performance on the HCT is strongly influenced by knowledge of resting heart rate. This raises the possibility that heart rate knowledge may mediate the previously-observed association between intelligence and HCT performance. Study One demonstrates an association between intelligence and HCT performance (N = 94), and Study Two demonstrates that this relationship is mediated by knowledge of the average resting heart rate (N = 134). These data underscore the need to account for the influence of prior knowledge and beliefs when examining individual differences in cardiac interoceptive accuracy using the HCT.