Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)




The effects of sensitivity of heart rate feedback on bidirectional heart rate control were examined by comparing two groups of 10 subjects who received feedback signals of either high or low sensitivity. Subjects in the high sensitivity condition received a feedback signal in which 1 cm of feedback meter needle movement was equivalent to an 8.57 beat-per-minute (BPM) change in momentary heart rate. The low sensitivity condition received a feedback signal which was one-half as sensitive, i.e. 1cm = 17.14 BPM change. All subjects received 8 sessions of training and each session included three within-session phases. The three within-session phases consisted of two (pre- and post-Feedback) Instructional Control phases during which subjects were instructed to accelerate or decelerate heart rate without the aid of feedback, and a Feedback phase during which bidirectional heart rate control was assisted by analogue heart rate feedback. Heart rate, frontal EMG, and respiration rate were recorded during all phases. The results showed that the low sensitivity condition produced larger mean heart rate accelerations than did the high sensitivity condition across all sessions and in the final session. No significant differences between the sensitivity conditions were found for heart rate decelerations or for the within-session phases. No differences between the sensitivity conditions were seen in frontal EMG or respiration rate. These findings were discussed in terms of Brener and Lang's models of learned heart rate control. Both models received some support from the present findings but it was concluded that both models are in need of revision. Possible effects of situational and biological constraints and motivational influences on this study's findings were examined. Finally, these findings were discussed in terms of implications for heart rate biofeedback research and applications.