Contingently faded heart rate biofeedback: Attempted replication of large-magnitude decreases

McKinney et al. (1980) reported large-magnitude reductions in heart rate (HR) from resting baseline levels, employing shaping and fading techniques and a reinforcement program in which a secondary reinforcer was awarded both contingently and immediately during training. The four male subjects in this group showed significantly greater HR decreases than a group of four males receiving beat-by-beat analogue HR feedback. The present study compared decreases in HR in 20 male subjects receiving the contingently faded biofeedback procedure to those shown by 10 male subjects for whom reinforcement was contingent on vigilant observation of a visual display, and independent of HR. The former group showed significantly greater decreases in HR that could not be attributed to elevated baseline levels. However, the decreases in HR were not as large as those reported by McKinney et al. (1980). It is argued that future research should assess variables contributing to individual differences in performance.This research was supported by Ontario Heart Foundation Research Grant 15–37 to R. Pavloski.     

Biofeedback training in frontalis muscle relaxation and enhancement of belief in personal control

The hypothesis that biofeedback training in frontalis muscle relaxation increases beliefs in internal (personal) locus of control was tested. Subjects were divided into two groups (internals and externals) based on Mirels' (1970) factor analyzedpersonal control subscale of Rotter's (1966) I-E Scale. Internal and external subjects were assigned randomly to one of three conditions: biofeedback (BF), false feedback (FF), or no feedback (NF). All subjects were measured on frontalis electromyographic (EMG) activity. Training consisted of three sessions spaced 1 week apart. Each session was comprised of a 5-minute baseline (nonfeedback) trial followed by a 20-minute experimental session. After each experimental session, subjects completed a questionnaire which assessed the extent to which they attributed their EMG performance to personal and environmental sources. After three sessions, subjects were posttested on the I-E Scale. Results indicated that subjects receiving BF reduced their EMG activity more than did subjects in either the FF or NF conditions, and this effect was maintained across all three sessions. Subjects who received BF shifted toward internal personal locus of control from pre- to posttesting, whereas no such change was found for either FF or NF subjects. Also, the relationship between BF training and change in personal locus of control was mediated by subjects attributing their EMG reduction more to personal effort than to properties of the task. Results are discussed in terms of the importance of contingent feedback as a determinant of cognitions of control.     

Simultaneous biofeedback of heart rate and frontal EMG as a pretraining for the control of EEG theta activity

Following one base-line session, 20 normal subjects received four half hour sessions consisting of simultaneous feedback of heart rate and frontalis muscle (pretraining). Ten subjects received contingent (CF), the other ten noncontingent feedback (NCF). Subjects were asked to lower heart rate and frontal muscle tension (EMG). Heart rate within sessions decreased up to 19 bpm, with a mean of 4 bpm for the CF group. There was only a weak decrease over sessions, however, because of the strong habituation effect. The following events accompanied the heart rate decrease: (1) an increase of the variability of the heart rate, (2) a decrease of the variance of the EMG, (3) an increased correlation between heart rate slowing and EMG decrease, and (4) an increasing subjective experience of control of heart rate and EMG. After pretraining, subjects received eight sessions of auditory feedback of their frontal EEG theta activity (four sessions with CF and four sessions with NCF in balanced order). There was a weak increase of theta for the CF condition over sessions, but a decrease within the sessions. Pretraining on heart rate and frontal EMG control had no influence on the performance during theta training. It was hypothesized that control of heart rate slowing and theta control involve different mechanisms.     

The effect of frontal EMG biofeedback training on the behavior of children with activity-level problems

N=1 withdrawal designs were employed with three children evidencing activity-level problems. Tutoring sessions occurred daily over a 2 1/2-month period. Each child was reinforced for decreasing frontalis muscle tension during auditory feedback while working arithmetic problems. Feedback was faded while tension reduction reinforcement was maintained. These procedures were repeated with reinforcement for increasing, rather than decreasing, muscle tension. Frontal EMG level, percent time on task, and motoric activity rate were obtained during sessions. Parent ratings of problem behavior in the home were recorded daily. Biofeedback with reinforcement was effective in both raising and lowering muscle tension. Effects were maintained by reinforcement. Results suggest a direct relationship between tension and activity levels. Academic performance and problem behavior improved significantly with reductions in EMG activity, although individual exceptions to these findings were present. Results lend support to the efficacy of frontal EMG biofeedback training in reducing activity, increasing attention to an academic task, and reducing problem behaviors.     

Comparisons of high, medium, and low feedback sensitivity for the control of heart-rate acceleration

Thirty-four student volunteers were randomly assigned to one of three feedback sensitivity conditions: high sensitivity, medium sensitivity, or low sensitivity. Each subject received four sessions of biofeedback training with instructions to accelerate heart rate. In each condition, analogue feedback was provided during heart-rate acceleration trials. In addition to heart rate, frontal EMG and digital skin temperature were also recorded. Results replicated and extended the findings of a previous study in that medium and low sensitivity feedback was found to be superior to high sensitivity feedback during the final training session. These results confirm previous findings that a high sensitivity feedback produces very poor control of heart-rate acceleration. These data were discussed in terms of motor skills theory and in terms of possible effects of feedback sensitivity upon the motivation of subjects.     

Differential shaping of EEG theta rhythms

Heart rate, EEG, frontal EMG, and forearm EMG were recorded in 20 subjects for 3 baseline, 8 feedback, and 2 postbaseline sessions in order to compare two biofeedback methods of teaching subjects to increase theta EEG activity. Subjects were divided into high- and low-EMG groups. Five high-EMG subjects, and 5 low-EMG subjects then received 8 sessions of strictly theta feedback. The remaining 10 subjects, 5 from the high-EMG group, and 5 from the low-EMG group, received a “graduated” training which involved shaping the target response. This procedure consisted of 4 initial sessions of EMG feedback, followed by a second phase consisting of 4 sessions of theta feedback. Results showed a clear relationship between subjects' baseline frontal EMG levels and the effect of the training methods. Although subjects with high-EMG baseline increased their theta output only with the two-phase training, subjects with low-EMG baseline levels performed better when given theta feedback only. This result shows not only that amounts of theta can be reliably increased, but that training techniques should be adapted to the physiological characteristics of the individual—in this case, baseline levels of frontal EMG levels.     

The effects of the distribution of training on learning feedback-assisted cardiac acceleration

In order to test a hypothesis derived from a motor skills learning model of cardiac acceleration control, groups of subjects were given biofeedback training for four sessions to learn cardiac acceleration under four different training schedules: (1) all sessions in one day, (2) daily sessions, (3) sessions every other day, and (4) weekly sessions. Ability to accelerate heart rate both with and without feedback was determined at each session. Also ability to accelerate heart rate without feedback was determined 1 week after the last training session as a measure of retention. Although there was highly significant (p less than.0001) evidence of heart rate control both with and without feedback, there were no differences in degree of control attributable to distribution of training sessions. There was, however, a trend (p less than .10) for subjects trained under the most distributed training schedule (weekly) to show more retention than subjects trained under a less distributed schedule (daily).     

Maintenance and generalization of 40-Hz EEG biofeedback effects

Maintenance of conditioning of 40-Hz EEG activity was investigated in six adults 1 to 3 years after they had experienced biofeedback training to increase 40-Hz EEG. Subjects were first retrained to alternately increase and suppress 40-Hz EEG. All six subjects achieved a preset performance criterion in 16–20 minutes. Five of these subjects also subsequently demonstrated significant control of 40-Hz EEG without feedback. The sixth subject did not demonstrate control after 76 minutes and four sessions of attempted retraining with feedback. Transfer of 40-Hz EEG control to a problem-solving task was tested in all subjects in a final session. Cognitive test items were presented and subjects were instructed to alternately increase and suppress 40-Hz EEG while solving the problems. Rates of 40-Hz EEG in suppression periods during problem solving were significantly greater than during suppression periods without problems. No significant differences in problem-solving performance were found comparing 40-Hz increase and suppression periods. This study supports previous research suggesting an association between 40-Hz EEG and mental activity, and suggests methods for further study of transfer of EEG biofeedback effects.     

Plasma catecholamine levels during temperature biofeedback training in normal subjects

Thirty-nine normal volunteers of both sexes were randomly assigned to receive 8 sessions of temperature biofeedback or autogenic training to increase finger temperature. Temperature biofeedback subjects produced significant elevations in finger temperature during training, whereas those who received autogenic training did not. Temperature feedback subjects had significantly higher heart rates and diastolic blood pressures during training compared to autogenic subjects. There were no significant changes or group differences in plasma catecholamine levels. These data do not support the hypothesis that feedback-induced vasodilation is accompanied by decreased sympathetic activation in normal populations, when only temperature biofeedback is employed.Supported by research grant No. HL-30604 from NHLBI. Dr. Angela McGuady served as Action Editor for this paper.     

Biofeedback-assisted sexual arousal in females a comparison of visual and auditory modalities

This study was undertaken to investigate the effects of instructional set and biofeedback modality upon the ability of 23 females to achieve control over sexual arousal. Two levels of instructional set (increase, decrease) were completely crossed with three feedback modalities (audio, visual, no feedback). Changes in vaginal blood volume (VBV) and vaginal pulse amplitude (VPA) were monitored by a vaginal plethysmograph and reduced on line by a microcomputer. During feedback trials, all subjects received audio- or visual feedback of the VBV response. Subjects participated in two sessions, each consisting of six 3-minute trials, one in each instruction/feedback combination. Order of trials was counterbalanced. Subjective levels of arousal, VBV, and VPA were significantly higher under increase instructions. Also, a significant feedback effect was noted in the subjective measure and the VBV measure, favoring visual feedback for overall control of sexual arousal. However, the feedback effect accounted for a small portion of the variance, and it was concluded that performance was not appreciably superior with or without feedback. Thus practical considerations may determine the feedback modality to be used for vaginal vasocongestion in future research. Higher positive correlations of subjective ratings with vaginal blood volume occurred during feedback trials, which suggests that biofeedback may be helpful in discrimination training to facilitate awareness of the feelings associated with different arousal levels and correct labeling of increased vasocongestion as sexual. Further research is necessary to see if sexually dysfunctional women can benefit from a biofeedback component in a comprehensive therapy program and to determine the effect of many training sessions on discrimination and self-control of arousal.     

Biofeedback-assisted sexual arousal in females: a comparison of visual and auditory modalities

This study was undertaken to investigate the effects of instructional set and biofeedback modality upon the ability of 23 females to achieve control over sexual arousal. Two levels of instructional set (increase, decrease) were completely crossed with three feedback modalities (audio, visual, no feedback). Changes in vaginal blood volume (VBV) and vaginal pulse amplitude (VPA) were monitored by a vaginal plethysmograph and reduced on line by a microcomputer. During feedback trials, all subjects received audio- or visual feedback of the VBV response. Subjects participated in two sessions, each consisting of six 3-minute trials, one in each instruction/feedback combination. Order of trials was counterbalanced. Subjective levels of arousal, VBV, and VPA were significantly higher under increase instructions. Also, a significant feedback effect was noted in the subjective measure and the VBV measure, favoring visual feedback for overall control of sexual arousal. However, the feedback effect accounted for a small portion of the variance, and it was concluded that performance was not appreciably superior with or without feedback. Thus practical considerations may determine the feedback modality to be used for vaginal vasocongestion in future research. Higher positive correlations of subjective ratings with vaginal blood volume occurred during feedback trials, which suggests that biofeedback may be helpful in discrimination training to facilitate awareness of the feelings associated with different arousal levels and correct labeling of increased vasocongestion as sexual. Further research is necessary to see if sexually dysfunctional women can benefit from a biofeedback component in a comprehensive therapy program and to determine the effect of many training sessions on discrimination and self-control of arousal.     

Contingentvs. noncontingent EMG feedback and hand temperature in relation to anxiety and locus of control

This study was designed to measure the effects of contingent and noncontingent EMG feedback on hand temperature, anxiety, and locus of control. Two groups of six subjects each were selected on the basis of high test-anxiety scores. The groups participated in a reverse design study in which Group 1 received five sessions of contingent EMG feedback followed by five sessions of noncontingent feedback. Group 2 received noncontingent feedback followed by contingent feedback. Results indicate a significant order of treatment effect. Subjects who received contingent feedback first produced lower EMG readings, lower test-anxiety scores, and higher hand temperatures during noncontingent feedback sessions. Receiving noncontingent feedback first may actually have interfered with utilizing contingent feedback.     

Effects of contingent versus yoked temperature feedback on voluntary temperature control and cold stress tolerance.

Twenty-four male internals (locus of control) and 24 externals were instructed to increase finger temperature under one of three conditions: (1) contingent feedback (CF), (2) yoked sham feedback (YF), or (3) no feedback (NF). Five 13-min training sessions were given. Feedback was then removed and subjects tested for voluntary temperature control. Finally, the cold pressor test, a laboratory analogue of natural cold stress, was administered under no-feedback conditions. Results demonstrated voluntary control of peripheral temperature following contingent feedback training, but not after yoked feedback temperature training. Contrary to expectation, the acquisition of voluntary control did not attenuate the stress response to thermal pain. Differences between internals and externals throughout the study were generally insignificant.     

Contingent vs. noncontingent EMG feedback and hand temperature in relation to anxiety and locus of control

This study was designed to measure the effects of contingent and noncontingent EMG feedback on hand temperature, anxiety, and locus of control. Two groups of six subjects each were selected on the basis of high test-anxiety scores. The groups participated in a reverse design study in which Group 1 received five sessions of contingent EMG ffedback followed by five sessions of noncontingent feedback. Group 2 received noncontingent feedback followed by contingent feedback. Results indicate a significant order of treatment effect. Subjects who received contingent feedback first produced lower EMG readings, lower test-anxiety scores, and higher hand temperatures during noncontingent feedback sessions. Receiving noncontingent feedback first may actually have interfered with utilizing contingent feedback.     

Biofeedback modification of frontal EMG in normal subjects

We carried out a controlled study on the voluntary control of the frontalis muscle by biofeedback procedures employing 20 normal subjects. Subjects were randomly divided into two groups of 10: (1) the biofeedback group and (2) the control group. Each of the two groups received five training sessions of about 40 minutes' duration each on different days. The results obtained are as follows: (1) In the biofeedback group, mean EMG levels decreased progressively and markedly from 2.16µVp-p min in the first session to 1.54µVp-p min in the last session. On the contrary, the control group did not show constant decreases in EMG levels over sessions. (2) The changes in the heart rate did not correlate with the changes in EMG activity. (3) The changes in the respiratory rate correlated with the changes in EMG activity.     

Respiratory Sinus Arrhythmia Versus Neck/Trapezius EMG and Incentive Inspirometry Biofeedback for Asthma: A Pilot Study

This pilot study compared biofeedback to increase respiratory sinus arrhythmia (RSA) with EMG and incentive inspirometry biofeedback in asthmatic adults. A three-group design (Waiting List Control n = 5, RSA biofeedback n = 6, and EMG biofeedback n = 6) was used. Six sessions of training were given in each of the biofeedback groups. In each of three testing sessions, five min. of respiratory resistance and EKG were obtained before and after a 20-min biofeedback session. Additional five-min epochs of data were collected at the beginning and end of the biofeedback period (or, in the control group, self-relaxation). Decreases in respiratory impedance occurred only in the RSA biofeedback group. Traub-Hering-Mayer (THM) waves (.03-.12 Hz) in heart period increased significantly in amplitude during RSA biofeedback. Subjects did not report significantly more relaxation during EMG or RSA biofeedback than during the control condition. However, decreases in pulmonary impedance, across groups, were associated with increases in relaxation. The results are consistent with Vaschillo's theory that RSA biofeedback exercises homeostatic autonomic reflex mechanisms through increasing the amplitude of cardiac oscillations. However, deep breathing during RSA biofeedback is a possible alternate explanation.     

Ocular and stabilization feedback: an evaluation of two EMG biofeedback control procedures

This study evaluated the adequacy of two novel EMG biofeedback control procedures. During a single training session, 36 subjects received either contingent EMG feedback from the frontal region (Veridical), contingent feedback for vertical eye movements (Ocular), or a feedback condition where the signal increased with deviations in any direction from baseline EMG levels (Stabilization). The results supported the use of Ocular but not Stabilization feedback as a control procedure in frontalis EMG biofeedback studies. Ocular feedback did not produce reductions in frontalis EMG but did lead to changes in subjective measures of nonspecific treatment effects that were at least comparable to those obtained with Veridical feedback. Stabilization subjects produced small but significant reductions in EMG, felt the most bored as a result of their feedback training, and were the most likely to rate themselves as having received false feedback. The implications of attribution theory and multiprocess relaxation theory for the evaluation of nonspecific treatment effects are discussed.     

Control of cardiac response under aversive stimulation

The relative heart rate effects of biofeedback training, deep muscle relaxation, and a no-feedback/music procedure were compared during two criterion situations. The first consisted of a 25-min training period during which subjects received the assigned treatments. The second consisted of the pre- to posttraining reductions in heart rate reactivity to a series of aversive tone-shock trials. On the first criterion, the heart rate decreases of the feedback and no-feedback/music groups were not clearly distinguishable; however, both groups fell significantly below the muscle-relaxation group. By contrast, on the second criterion, the three groups were clearly distinguishable, with feedback subjects evidencing the most heart rate control, followed by the muscle-relaxation and no-feedback/music groups, respectively. On the segment of the posttraining aversive trials conducted in the absence of the feedback signal, transfer of heart rate control was incomplete for feedback subjects, but still remained below the level of the other two groups. Training effects were more pronounced on tonic than on phasic heart rate changes. The difference between the two criterion situations suggests the possible need for and feasibility of employing a situational arousal methodology in evaluating the extent and limitation of physiological training procedures.     

Variations in digital temperature during frontal EMG biofeedback training in normal subjects

During frontal EMG biofeedback training, the relationship between frontal EMG and digital skin temperature was investigated in two experiments, which varied the number of baseline and feedback sessions. The results of Experiment 1 suggested a "general relaxation effect," where digital temperature increased as frontal EMG decreased, especially for subjects with initially low hand temperature. Experiment 2 extended the number of baseline and feedback sessions and qualified the results of Experiment 1. EMG and digital temperature did not simultaneously converge toward general relaxation over the extended baseline or feedback sessions in Experiment 2. Furthermore, when the feedback signal was introduced, digital temperature dropped quickly but recovered to baseline levels within three feedback sessions; this drop in digital temperature was interpreted within the context of attentional demands of the biofeedback task. The results appeared consistent with the view that frontal biofeedback training teaches a discriminative skill of lower frontal EMG, and that this skill does not readily generalize to digital skin temperature.     

Heart-rate reactivity to cold pressor stress following biofeedback training

Three previous studies have shown that biofeedback training is useful in modifying heart-rate and pain ratings during ice water stimulation (cold pressor test). Subjects were given an initial cold pressor followed by heart-rate biofeedback training and a final cold pressor test in which they were instructed to control their heart rate in accordance with the prior training. It was assumed that a heart-rate control skill had been learned. In the present study, two groups of subjects (N = 9 each) were given either increase or decrease heart-rate biofeedback training following the same procedures as previously, but subjects were not instructed to control their heart rate during the final cold pressor test. Heart rate, skin conductance, electromyographic activity, and respiration were measured. The biofeedback training effects replicate the previous results. However, no heart-rate or pain rating differences were found between the two groups during the final cold pressor test. Thus, previous findings cannot be accounted for simply by a shift in heart rate and/or pain reactivity following training itself. The findings suggest that a biofeedback strategy may be useful in modifying physiological and subjective responses to painful stimuli but only if it can be used as an active coping skill.