Individual differences in heart rate regulation : an exploratory investigation
Date
1976
Authors
Egner, Karl
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Abstract
Demonstrations of heart rate regulation in humans have frequently revealed marked individual differences in performance. These differences appear to be reliable over time and have prompted several investigations aimed at their elucidation. These investigations have, however, dealt primarily with psychological (personality) variables, neglecting potentially important physiological variables. The present study was primarily concerned with an invesĀtigation of two such variables, tonic heart rate preceeding regulation trials (initial level) and heart rate reactivity. The psychological variable of incentive was also examined.
Exploration of the effects of initial level across subjects involved a comparison of absolute level scores (uncorrected) and transformed level scores (corrected) which adjusted for individual differences in the upper and lower bounds of cardiac rate. Reactivity was estimated, prior to the attempted heart rate regulation, using a respiratory manipulation to elicit both acceleratory and deceleratory heart rate responses, The relationships between these physiological variables and heart rate increase and decrease regulation were assessed in separate multiple regression analyses for each direction.
The regulation procedure itself involved five 4 min trials for each direction of attempted regulation with visual, analogue feedback being available on the last four trials. The incentive manipulation was introduced in conjunction with the regulation segment of the experiment: for incentive subjects a monetary reward was offered for the best overall regulation performance and for no-incentive subjects an identical sum of money ($20) was awarded according to a random draw.
Analyses of the regulation data revealed significant heart rate changes in both directions, with increases being larger than decreases. Changes in both directions were, however, relatively small in comparison with other reports in the literature. This difference was attributed to the fact that, in the present study, instructions to the subjects may have more effectively restricted somatic changes. The incentive manipulation proved ineffective, likely for reasons specific to the particular incentive condition used in this study.
The multiple regression analyses revealed nonĀ-significant overall regression effects, however some interesting trends did appear. Uncorrected and corrected initial level showed some relationship to increase and decrease performance respectively and these relationships were discussed in the context of the Law of Initial Values (Wilder, 1957).
The correlation between decrease reactivity and decrease regulation also approached significance: it was suggested that this relationship might reflect the involvement of a respiratory strategy in regulation.