The Role of Feedback in Control of Heart Rate Variability.

The effects of contingent feedback (CF), non-contingent feedback (NCF), and no feedback (NFl on heart rate (HR) variability control were studied. Nine matched trios of subjects were given training in HR variability control on 3 consecutive days. CF and NCF subjects attempted HR variability control while HR feedback was continuously presented, and NF subjects attempted HR variability control without feedback. During the training periods the CF group produced reliably lower mean HR variance than the NF group, but the NCF group was not reliably different from either of those groups. There was no significant difference among groups in negative linear trend across training periods, and the CF group did not continue to produce decreasing HR variances over sessions. However, the CF and NCF groups showed reliable quadratic trends, Indicating an initial drop in HR variance followed by a return to pretraining levels. Both CF and NCF groups showed rapid, reliable increases in respiration rate during training periods. The results pose serious problems for studies which have reported feedback-related control of HR variability. [ABSTRACT FROM AUTHOR]

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