Key result
Comparing heart rate control to an initial pre-experiment baseline artifactually favors finding large decreases, whereas using a running pretrial baseline favors finding large increases.
Why the study?
Does the choice of baseline (pre-experiment vs. pretrial) affect the measured magnitude of voluntary bidirectional control of heart rate in male undergraduates?
Does the choice of baseline (pre-experiment vs. pretrial) affect the measured magnitude of voluntary bidirectional control of heart rate in male undergraduates?
The magnitude of voluntary directional heart rate control is artifactually influenced by the choice of baseline (initial vs. running pretrial), highlighting methodological considerations in biofeedback studies.
Baseline choice may artifactually bias heart rate biofeedback results; leaves open true voluntary control magnitude pending standardized pretrial methods.
The purpose of this study was to compare two methods of analyzing the effects of exteroceptive feedback training on the voluntary bidirectional control of human cardiac rate with the use of a within-subject control design. In this design heart rate (HR) during an experimental period (increase or decrease) is compared with that recorded during some other control period, generally a baseline "rest" period. Ten male undergraduates were instructed to control HR and given visual feedback of heart activity. Trials on which Ss were to raise and to lower HR were both given in a single training session. The data were analyzed in two ways: (a) cardiac rate during HR control periods was compared to an initial pre-experimetn baseline; (b) cardiac rate during HR control periods was compared to a running pretrial baseline. The results support the argument that the former procedure fails to take account of habituating levels of cardiac rate and favors finding large magnitude decreases in HR but small increases, whereas the latter procedure favors finding large magnitude increases but small decreases. It is suggested that magnitude of directional control will be artifactual when initial values are used to assess change. Contaminating influences on the running pretrial baseline were also discussed.
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Blankstein et al. (1976) studied this question. Exteroceptive feedback training vs. Pre-experiment baseline vs running pretrial baseline was evaluated on Cardiac rate during HR control periods. Comparing heart rate control to an initial pre-experiment baseline artifactually favors finding large decreases, whereas using a running pretrial baseline favors finding large increases.
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