SENSITIVITY TO MECHANICAL STIMULI AND THE ROLE OF GENERAL SENSORY ANDPERCEPTUAL PROCESSES IN HEARTBEAT DETECTION

Sensitivity to heartbeat sensations is commonly assessed using tasks t hat require individuals to judge the simultaneity of heartbeats and to nes. In two experiments, we investigated the suitability of this parad igm for examining cardioception. In the first experiment, participants judged the simultaneity of near-threshold vibrations and suprathresho ld tones. Precision in judging vibration-tone simultaneity was directl y related to the detectability of the mechanical stimuli, thereby supp orting use of the simultaneity paradigm to assess heartbeat detection. In the second experiment, we examined the influences of sensitivity t o mechanical stimuli and the ability to make intermodality simultaneit y judgments on the precision of heartbeat detection. We measured parti cipants' vibrotactile thresholds, precision in judging light-tone simu ltaneity, and precision in judging heartbeat-tone simultaneity. The ab ility to judge the simultaneity of lights and tones accounted for 24.3 % of the variance in precision of heartbeat detection, and mechanical sensitivity accounted for a further 8.5%.