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).     

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 role of behavioral conditioning in the cardiovascular adjustment to exercise

The purpose of this study was to determine if normal subjects could be trained to attenuate their cardiovascular responses while exercising on a bicycle ergometer. Ten young, untrained subjects exercised on a bicycle ergometer for five sessions. Half of the group was asked to slow their heart rate while exercising with heart rate feedback during exercise. Their average heart rate increase was 20% less than that of the control subjects, who exercised without feedback. The control subjects subsequently also received feedback during exercise and they were able to attenuate their heart rate responses comparably. Systolic blood pressure was not affected by feedback training. Changes in rate-pressure product paralleled changes in heart rate. These data show that autonomically mediated adjustments to exercise can be brought under experimental control through the use of appropriate behavioral techniques.     

Voluntary heart rate deceleration: A critical evaluation

This experiment was designed as a test of the view that the human heart rate (HR) deceleration response can be brought under voluntary control, when some form of exteroceptive feedback is available. Sixteen female volunteers were randomly assigned to two groups. The first group received instructions to decrease their HR plus a continuous negative (failure) binary feedback, while the second group received only the instructions. Each subject was given four sessions of HR deceleration training. Two identical tests were presented, one before and the other after the series of training sessions. These tests were divided into two parts. In the first part, subjects attempted to decrease their HR while undergoing an ischemic arm pain stress. In the second part, subjects performed a 40-trial HR discrimination task. The results indicate that all subjects decrease HR during both rest and voluntary control periods within each training session, but there are no significant group differences, no improvement in HR deceleration control over the four training sessions, and no difference in performance between rest and voluntary control periods. Similarly HR, blood pressure (BP), and the HR×BP product levels during the ischemic stress condition and the HR discrimination performance do not show group differences. It is suggested that the HR deceleration response may not meet the criteria generally applied to the definition of a voluntary response.     

Varying temporal location of a conditioned stimulus in heart rate conditioning of Macaca mulatta

The several functions that a stimulus can assume were investigated in a Pavlovian conditioning procedure. The subjects were six rhesus monkeys; the response under observation was heart rate. The conditioning began with a temporal separation of zero between a signal and a regularly repeating electric shock; the signal was then moved to a series of earlier locations in the inter-shock interval. After six sessions at each location, two sessions followed in which only the shock was delivered periodically. The findings included: (1) A two-phased conditioned cardiac rate response seen at the first location became more multiphasic and irregular during longer intervals between signal and shock; (2) the location where the conditioned response peaked became increasingly variable as the signal was moved back, but this variability maintained a constant proportion to the signal-shock interval; and (3) heart rate during a presignal period, and during a comparable period in shock only sessions, was generally deceleratory early in training and acceleratory thereafter. Sessions with the signal showed heart rate in the presignal period to have become acceleratory earlier in training than sessions with shock only. The data pertain to stimulus control over heart rate as a function of: (A) the temporal proximity of a signal to an aversive stimulus; and, (B) the presence or absence of the signal. The use of appropriate response units in cardiac conditioning is also discussed.     

Behavioral and electroencephalographic correlates of 40-Hz EEG biofeedback training in humans

Two groups of eight adults successfully trained with biofeedback for increases in 40-Hz EEG responses in left or right hemispheres also demonstrated significant 40-Hz EEG increases during baseline periods, and increases in the contralateral hemisphere during training periods. No changes in heart rate, 40-Hz EMG, or 21- to 31-Hz beta, alpha, or theta EEG occurred over training days. Three subjects returning for additional training demonstrated suppression of 40-Hz EEG. A group of four subjects experiencing daily bidirectional training produced substantial within-session control of 40-Hz EEG but no changes over days. Data from posttraining tests without feedback for successful subjects in both groups indicated significant control of 40-Hz EEG responses in the initial parts of these sessions, and some correlated changes in other EEG responses. Measures of successful subjects' experiences during training and control tests indicated awareness of changes in subjective concomitants of EEG responses. This study suggests further strategies for research on behavioral correlates of EEG activity.     

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.     

The production and generalization of large-magnitude heart rate deceleration by contingently faded biofeedback

Eight subjects were taught to decrease their heart rates via biofeedback training. Four of these received contingently faded, beat-by-beat analogue feedback and contingent reinforcement each time their performance met a specified and adjusting criterion. The other four received continuous, beat-by-beat analogue feedback, but not the contingent reinforcement. Subjects in the two groups were yoked to ensure equal densities of reinforcement. Subjects in the first group were asked to decrease heart rates 15% from baseline and were then trained using only 75%, 50% and 25% of beat-by-beat feedback. It was hypothesized that the immediate reinforcement of appropriate behavior and the contingent fading(following mastery) of feedback would aid in the generalization of the response. Following completion of all criterion steps or 10 training sessions, whichever came first, all subjects were tested with no feedback and no contingent reinforcement. The group receiving contingently faded feedback training showed a significantly greater heart rate decrease in the training sessions and also the test session. These results were interpreted as indicating that biofeedback can be conceptualized as an operant conditioning paradigm, and that the use of operant techniques may help subjects produce clinically significant changes.This research was supported in part by a grant to Robert J. Gatchel from the National Heart, Lung, and Blood Institute (Grant No. NIH HL 21426-01).     

Specificity of finger pulse volume feedback during relaxation

The effect of biofeedback during brief periods of relaxation was examined. Two groups (10 subjects in each group) were asked to relax as completely as possible during a series of six 3-minute relaxation periods in each of two 1-hr sessions. One group received biofeedback based on finger pulse volume (FPV) during the relaxation trials, while the other group received no biofeedback. Measures of heart rate, respiration rate, skin conductance level, and FPV were recorded during the sessions, and subjective ratings concerning relaxation were obtained after each session. The results showed that FPV scores for the groups differed during the relaxation trials of the second session, but other measures failed to distinguish between the groups. The group that received FPV feedback revealed a significantly higher level of FPV (relative to baseline) than the group that received no feedback.     

Central control of cardiovascular adjustments to exercise

Voluntary heart rate (HR) control during moderate exercise on a bicycle ergometer was studied in 10 healthy physically conditioned men (5 experimental and 5 control). The results showed that subjects could learn to attenuate the tachycardia of exercise while exercising at a steady work level of 60-70% of maximum HR. Experimental subjects who saw beat-to-beat displays of HR and were instructed to slow HR showed 22% less increase in HR than did control subjects who exercised without HR displays or instruction to slow HR (42.6 vs. 54.6 beats/min). When the control subjects were given feedback in additional sessions, they also decreased HR significantly by 9% (54.6 vs. 49.9 beats/min). Analyses of concomitant respiratory and metabolic data showed that HR attenuation was accompanied by decreased O2 consumption (P less than 0.06) and pulmonary ventilation (P less than 0.01). Rate pressure product also fell, indicating a decrease in myocardial O2 consumption. Comparisons among pre- and postsubmaximal and cardiovascular pulmonary and humoral responses during maximal test sessions suggested that the improvement in cardiopulmonary function during feedback training occurred with no sacrifice to working muscle requirements because blood lactate concentrations were similar. The attenuation of the HR response obtained in the present study indicates that feedback training in physically conditioned subjects can influence cardiovascular responses even under conditions of heavy local demands imposed by working muscles.     

Learned control of heart rate during exercise in patients with borderline hypertension

Twelve patients with borderline hypertension [less than or equal to 21 X 33/12.6, greater than or equal to 18 X 6/12.0 kPa (less than or equal to 160/95; greater than or equal to 140/90 mm Hg)] participated in an experiment aimed at testing whether they could learn to attenuate heart rate while exercising on a cycle ergometer. Six experimental (E) subjects received beat-to-beat heart-rate feedback and were asked to slow heart rate while exercising; six control (C) subjects received no feedback. Averaged over 5 days (25 training trials) the exercise heart-rate of the E group was 97.8 bt min-1, whereas the C group averaged 107 bt min-1 (P = 0.03). Systolic blood pressure was unaffected by feedback training. Generally, changes in rate-pressure product reflected changes in heart-rate. Oxygen consumption was lower in the E than in the C group late in training. We conclude that neurally mediated changes associated with exercise in patients with borderline hypertension can be brought under behavioral control through feedback training.     

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.     

Changes in autonomic responding to stress after practice at controlling heart rate

Subjects in this experiment viewed a stressful film and then received one of five treatments: (a) practice at increasing heart rate without feedback, (b) practice at decreasing heart rate without feedback, (c) practice at increasing heart rate with feedback, (d) practice at decreasing heart rate with feedback, or (e) a control condition. Subjects then returned on the following day, practiced controlling heart rate again (or sat quietly, for subjects in the control condition), and then viewed the stressful film again. Heart-rate results indicated that subjects in both feedback groups manifested tonic decreases in heart rate from the first viewing of the film to the second, whereas subjects in both of the no-feedback groups manifested no changes in heart rate between viewings, and subjects in the control condition manifested increases in heart rate between viewings. However, all five groups of subjects displayed phasic increases in heart rate during specific stressors in the film during both viewings. The tonic changes in heart rate noted between viewings of the film for the feedback groups were not accompanied by parallel changes in electrodermal activity or respiration rate. Self-report ratings of subjects' beliefs about ability to control heart rate were significantly correlated with the tonic changes in heart rate that were noted between viewings of the stressful film.     

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.     

A comparison of the mechanisms and some properties of instructed sudomotor and cardiac control

Instructed control defined as differential compliance with verbal instructions to increase and decrease a response was assessed when a change in sudomotor activation or heart rate was specified as the behavioral goal. Instructed control of heart rate was evident prior to explicit feedback training for this response, but instructed control of sudomotor activation defined as finger sweating and measured as skin conductance was not. Feedback training subsequently established instructed control of sudomotor responding, but such training did not lead to a significant improvement in control of heart rate. Explicit strategy suggestions emphasizing emotional responding and intended or actual movement appeared to interfere with the performance of instructed control under both target conditions. Instructed changes in heart rate were attended by correlated changes in somatomotor and respiratory function. Somatomotor and respiratory responses were also observed when subjects were instructed to change sudomotor activation, but these correlated activities were of small magnitude and were not augmented by feedback training as was target responding. Several accounts of the basis for differences that were evident between the target conditions with respect to feedback effects and response patterns are discussed.These experiments constituted a doctoral dissertation submitted to McMaster University by J. M. Lacroix. The research was supported by grants from the National Research Council of Canada (A0132) and the Ontario Mental Health Foundation (345) to L. E. Roberts, who was thesis supervisor. Supplementary data analyses were supported by a grant from Glendon College to J. M. Lacroix. We wish to thank A. H. Black for his comments on this work.     

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.     

Feedback control of human alpha rhythm from the central area

Twenty subjects, aged 17 to 25, were given from 5 to 10 sessions of training in controlling alpha. They were divided into three groups, respectively reinforced for increasing alpha from the central area, reinforced for decreasing alpha from the central area, and given noncontingent reinforcement. Compared with the initial baseline, the alpha of the noncontingent subjects did not change, while those reinforced for increases were reliably higher and those reinforced for decreases reliably lower than the noncontingent group. A slight trend toward improvement during successive sessions was not reliable. Since the experiment was conducted in the Soviet Union, the subjects had no expectations of an “alpha experience.” Although tests showed a slight elevation in mood at the end of the sessions, there were no differences among the groups. There was an increase in reports of fatigue after the training sessions. There were no reports of using visual or somatomotor maneuvers as a means of controlling alpha. Furthermore, alpha rhythm control was not found to be consistently correlated with changes in heart rate, respiration, or mood, as determined by cross-correlation analysis.     

Feedback control of human alpha rhythm from the central area.

Twenty subjects, aged 17 to 25, were given from 5 to 10 sessions of training in controlling alpha. They were divided into three groups, respectively reinforced for increasing alpha from the central area, reinforced for decreasing alpha from the central area, and given noncontingent reinforcement. Compared with the initial baseline, the alpha of the noncontingent subjects did not change, while those reinforced for increases were reliably higher and those reinforced for decreases reliably lower than the noncontingent group. A slight trend toward improvement during successive sessions was not reliable. Since the experiment was conducted in the Soviet Union, the subjects had no expectations of an "alpha experience." Although tests showed a slight elevation in mood at the end of the sessions, there were no differences among the groups. There was an increase in reports of fatigue after the training sessions. There were no reports of using visual or somatomotor maneuvers as a means of controlling alpha. Furthermore, alpha rhythm control was not found to be consistently correlated with changes in heart rate, respiration, or mood, as determined by cross-correlation analysis.     

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.