A method of constant stimuli for examining heartbeat detection: comparison with the Brener-Kluvitse and Whitehead methods.

A method of constant stimuli (MCS) for measuring heartbeat detection was examined by comparing performance on this method with the Brener and Kluvitse (BK) method and a variant of the Whitehead (WH') method. All methods required subjects to judge the simultaneity of heartbeat sensations and tones, and each yielded measures of judgment precision and of the temporal location of heartbeat sensations relative to the electrocardiogram R-wave. Both measures were found to be significantly correlated across tasks. A greater proportion of subjects met criteria for classification as heartbeat detectors on the MCS (54%) and BK (50%) tasks than on the WH' task (33%). In the MCS and BK tasks, subjects judged tones presented 100-300 ms after the R-wave to be most simultaneous with heartbeat sensations. Intratask correlations showed that only the MCS procedure yielded stable measurements of both judgment precision and temporal location. The MCS procedure possesses commendable psychometric properties and provides a simpler means than the BK procedure of examining heartbeat detection.