EMG stability as a biofeedback control

Factors that may confound comparisons between electromyographic (EMG) biofeedback training and its control conditions include feedback quality and experience of success. We investigated the usefulness of a control procedure designed to overcome these potential sources of confounding. The procedure consisted of training muscle tension stability. We used it as a control for frontal EMG relaxation training in children with asthma. To equate the groups for feedback quality and experience of success, we gave each child in the control condition audio feedback decreasing in pitch when muscle tension was at or near baseline levels, and feedback increasing in pitch when muscle tension was either substantially above or below baseline levels. Children in both groups were instructed to decrease the pitch of the tone. In comparison to children in the relaxation condition, the children in the control condition exhibited stable levels of muscle tension throughout eight training sessions. We concluded that feedback for stable muscle tension may be a useful control procedure for EMG biofeedback training whenever experimental and control procedures differ in either feedback quality of degree to which they permit subjects to experience success.This research was supported by NIH-Grant HL 27402. We are grateful to Paul Schnitter who constructed the EMG stability feedback device.     

The effects of EMG feedback training during problem solving: a case study.

The present case study investigated the effects of competing task demands on biofeedback training to reduce frontalis muscle tension. Baseline levels of frontalis muscle tension were recorded for relaxation and problem solving. The subject was trained to decrease muscle tension with biofeedback for the problem-solving task alone. The results indicated that EMG training during problem-solving was successfully accomplished. Frontalis muscle tension during relaxation baseline did not change as a result of reductions in muscle tension during problem-solving feedback training. This suggests that the decrease of muscle tension cannot be attributed to reductions in overall muscle tension levels. Instead, training was specific to the problem-solving feedback phases. Additionally, it was found that accuracy in problem-solving did not decline as a result of simultaneous feedback training. Thus EMG biofeedback training can be accomplished and exercised without disruption of ongoing mental activity.     

The effects of EMG feedback training during problem solving

The present case study investigated the effects of competing task demands on biofeedback training to reduce frontalis muscle tension. Baseline levels of frontalis muscle tension were recorded for relaxation and problem solving. The subject was trained to decrease muscle tension with biofeedback for the problem-solving task alone. The results indicated that EMG training during problem solving was successfully accomplished. Frontalis muscle tension during relaxation baseline did not change as a result of reductions in muscle tension during problem-solving feedback training. This suggests that the decrease of muscle tension cannot be attributed to reductions in overall muscle tension levels. Instead, training was specific to the problem-solving feedback phases. Additionally, it was found that accuracy in problem-solving did not decline as a result of simultaneous feedback training. Thus EMG biofeedback training can be accomplished and exercised without disruption of ongoing mental activity.     

Generalization of lowered EMG levels during musical performance following biofeedback training

Electromyographic (EMG) biofeedback training offers a means by which musicians can control excess muscle tension during performance. Music instructors generally agree that unnecessary muscle tension not only leads to physical problems but also can interfere with performance quality. It is important, however, that the reduced EMG levels resulting from biofeedback training generalize to situations in which feedback is not available, and that the reduction in muscle tension not result in decreased performance quality. Eight intermediate to advanced clarinet players participated in four EMG biofeedback training sessions during which short-term and extended generalization of lowered EMG levels was assessed along with trill and scale speed scores. Significant reductions in EMG levels associated with biofeedback training generalized to short-term and extended situations, while trill and scale performances remained at or above pretest levels.     

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.     

Expectancies of reinforcement control in biofeedback and cognitive performance

This study investigated the effects of expectancies concerning the controllability of outcomes in a biofeedback task. Forty-eight college undergraduates were subjects. Frontal (forehead) electromyographic (EMG) responses were measured during baseline (no treatment), pretreatment, and test sessions. During pretreatment, subjects were assigned to one of three groups. Using a fictitious blood vessel control task, the success group received false feedback and instructions that conveyed that outcomes had been successfully controlled. The failure group received feedback and instructions that conveyed that outcomes had not been controlled. A control group was given no specific task. During the subsequent test stage, all subjects were asked to reduce frontal muscle tension levels through relaxation while assisted with true EMG feedback. Relative to the success and control groups, EMG levels of the failure group reflected more rapid acquisition of frontal muscle relaxation. However, performance on a cognitive task was not affected by the pretreatment. It was concluded that expectancies generated during the false feedback pretreatment were related to later biofeedback performance. The results were discussed in terms of concepts of locus of control and theories of learned helplessness and reactance.A version of this paper was presented at the annual meeting of the Biofeedback Society of America, San Diego, 1979.     

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 (1) contingent EMG feedback from the frontal region (Veridical), (2) contingent feedback for vertical eye movements (Ocular), or (3) 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.This research was supported in part by grants from the National Institutes of Health (AM31500) and the Robert Wood Johnson Foundation. Portions of this research were presented at the Sixth Annual Meeting of the Society of Behavioral Medicine, New Orleans, March 1985.     

The use and utility of EMG biofeedback with chronic schizophrenic patients

This study examined the efficacy of muscle relaxation training via electromyographic (EMG) biofeedback from the frontalis and forearm extensor muscles of schizophrenic inpatients. Thirty chronically hospitalized patients were randomly assigned to one of three conditions: EMG biofeedback from the forearm extensor and frontalis muscles, progressive relaxation, and a control group. Treatment consisted of one session of orientation and baseline, and six sessions of training. The results indicated that the schizophrenic patients receiving EMG training had significantly lower EMG recordings than the progressive relaxation group, which, in turn, was significantly lower than the control group. Analyses of covariance on the Tension-Anxiety scale from the Profile of Mood States revealed no significant effects, while finger-tapping rates were significantly improved only for the arm receiving feedback training in the EMG group. On the Nurses Observation Scale for Inpatient Evaluation the biofeedback group significantly improved on the Social Competence and Social Interest factors.     

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.     

Awareness during electromyographic biofeedback: Of signal or process?

During relaxation training, awareness of trial-to-trial changes in frontalis-muscle tension levels was assessed with and without auditory electromyographic(EMG) biofeedback. Immediately after each 128-sec training trial, the subject was required to guess whether muscle tension indexed by EMG activity increased(“Up”) or decreased(“Down”) relative to the immediately preceding trial. The probability of correct guessing, P(c), improved as the absolute difference in EMG increased between trials only when biofeedback was presented. For subjects not receiving biofeedback, P(c) remained low even when the absolute difference between trials was large. Subjects in each condition employed a strategy to guess “Down” more often consistent with the expectation that they were being trained to relax. The “Down” set strategy was shown to be separable from the informational basis of P(c) provided by biofeedback. This procedure can be employed to evaluate central assumptions of biofeedback relating to posttraining awareness of changes in muscle tension and the relationship between awareness and control of muscle tension.     

The relative effectiveness of three techniques to induce the trophotropic response.

The purpose of this study was to examine the relative effectiveness of electromyographic biofeedback training (EMG BFT), meditation, and progressive muscle relaxation (PMR) in eliciting a relaxation or trophotropic response as measured by frontalis muscle tension, heart rate, electrodermal response, respiration rate, and skin temperature. Fifty-four college students were randomly assigned to one of five groups: (1) control, (2) placebo control, (3) EMG BFT, (4) meditation, (5) PMR. After baseline measures were obtained subjects were trained in 10 30-minute training sessions and posttested. Comparisons by ANOVAs indicated there was a significant decrease in muscle tension in the EMG BFT and meditation groups and significant decreases in respiration rate in the meditation and PMR groups. No other changes were attributed to treatment.     

Cognitive and physiologic responses to EMG biofeedback and three types of pseudofeedback during a muscular relaxation task

Four groups of normal human subjects were tested for their ability to reduce frontal muscle tension levels during presentation of veridical auditory biofeedback or auditory pseudofeedback. A double-blind methodology was used. Three groups of subjects assigned to the pseudofeedback conditions received a feedback signal that was not contingent on EMG activity but that followed one of three different patterns. One group received a truly random signal, the second received a signal that gradually increased in frequency (apparent failure), and the third received a signal that gradually decreased in frequency (apparent success). Dependent measures included both physiologic (frontal and neck EMG) and subjective reactions to the relaxation task. The different patterns of pseudofeedback did produce reliably different subjective responses, suggesting that the manipulations succeeded in producing unequal nonspecific effects that were unrelated to the feedback contingency specifically. However, these differential subjective effects were not strongly reflected in the physiologic responses since the differences in EMG levels among the four groups did not differ significantly at any stage of training. An analysis of the integrity of the double-blind procedure showed that although experimenters were effectively kept blind to group assignment, subjects' responding suggested a response bias as well as the possibility that the double-blind was breached. The utility of the double-blind methodology in biofeedback experiments is discussed and suggestions for future research are offered.     

Crosscultural differences in frontalis muscle tension levels: An exploratory study comparing Japanese and Westerners

This paper describes a comparison between Japanese (N=20) and Westerners (N=20) in their respective frontal EMG levels and their ability to relax during one 5-minute biofeedback training session. The data indicated a significantly lower baseline muscle tension level in Japanese than in Westerners. After EMG biofeedback, however, no significant difference was found between the two groups. Japanese females showed significantly higher tension levels both during baseline and biofeedback phases than did Japanese males.     

Crosscultural differences in frontalis muscle tension levels: an exploratory study comparing Japanese and Westerners

This paper describes a comparison between Japanese (N = 20) and Westerners (N = 20) in their respective frontal EMG levels and their ability to relax during one 5-minute biofeedback training session. The data indicated a significantly lower baseline muscle tension level in Japanese than in Westerners. After EMG biofeedback, however, no significant difference was found between the two groups. Japanese females showed significantly higher tension levels both during baseline and biofeedback phases than did japanese males.     

Feedback delays and relaxation expectancies in EMG biofeedback

The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yield results confounded by differential expectancies for relaxation. Furthermore, the role of expectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects of feedback delays and induced relaxation expectancies on EMG activity and experienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one of four computerized feedback delay conditions (0.0037, 0.7493, 2.2481, 6.7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affecting EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expectancies. Instrumental and expectancy factors in EMG biofeedback appear to operate independently of each other by reducing physiological activity and producing psychological relaxation respectively.     

The use and utility of EMG biofeedback with chronic schizophrenic patients

This study examined the efficacy of muscle relaxation training via electromyographic (EMG) biofeedback from the frontalis and forearm extensor muscles of schizophrenic inpatients. Thirty chronically hospitalized patients were randomly assigned to one of three conditions: EMG biofeedback from the forearm extensor and frontalis muscles, progressive relaxation, and a control group. Treatment consisted of one session of orientation and baseline, and six sessions of training. The results indicated that the schizophrenic patients receiving EMG training had significantly lower EMG recordings than the progressive relaxation group, which, in turn, was significantly lower than the control group. Analyses of covariance on the Tension-Anxiety scale from the Profile of Mood States revealed no significant effects, while finger-tapping rates were significantly improved only for the arm receiving feedback training in the EMG group. On the Nurses Observation Scale for Inpatient Evaluation the biofeedback group significantly improved on the Social Competence and Social Interest factors.We would like to express our appreciation for the contributions the following people made to this project: Drs. Barry Smith, Robert Steele, Agnes Hartfield, Jeffrey Barth, Althea Wagman, and the late Harold Weiner; Earl Downs and the participating staff at Springfield State Hospital Center; and Robert Kline and Michael Kelley, who performed the data analyses. This research was supported in part by a grant from the Computer Science Center at the University of Maryland.     

Effectiveness of multiple muscle-site EMG biofeedback and relaxation training in reducing the aversiveness of cancer chemotherapy

A 44-year-old female cancer patient was given progressive muscle relaxation training and multiple muscle-site EMG biofeedback to reduce the conditioned negative responses she had apparently developed to her chemotherapy treatments. Following three baseline chemotherapy sessions, the patient was given relaxation training and biofeedback during four consecutive chemotherapy treatments and was asked to practice her relaxation skills daily in the hospital or at home. After the patient felt able to relax on her own, relaxation training and biofeedback were terminated and three follow-up sessions were held. Results indicated that during the chemotherapy sessions in which the patient received relaxation training and biofeedback, she showed reductions in physiological arousal (EMG, pulse rate, systolic blood pressure, and diastolic blood pressure) and reported feeling less anxious and nauseated. Moreover, these changes were maintained during the follow-up sessions. These results suggest that relaxation training plus multiple muscle-site biofeedback may be an effective adjunctive procedure for reducing some of the adverse side effects of cancer chemotherapy.     

Effectiveness of multiple-site EMG biofeedback in the reduction of arousal

During the training phase, 36 subjects received (a) EMG biofeedback from multiple muscle sites, (b) EMG biofeedback from the frontal site, or (c) no biofeedback. Results indicated that neither biofeedback procedure reduced self-reports of anxiety, but that multiple-site biofeedback was effective in reducing several indices of autonomic arousal (pulse rate, finger pulse volume, and skin temperature) while frontal biofeedback was not. During the generalization/stress phase, all subjects were threatened with and received electric shocks and were told to apply the relaxation techniques they learned during the training phase even though no additional biofeedback would be provided. Results indicated that multiple-site biofeedback was effective in reducing self-reports of anxiety and autonomic arousal but that frontal biofeedback was not. These results confirm previous data indicating that frontal biofeedback is not an effective procedure for controlling stress, but suggest that EMG biofeedback can be effective in reducing self-reported anxiety and autonomic arousal if a multiple muscle-site feedback procedure is employed.     

Feedback delays and relaxation expectancies in EMG biofeedback

The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yield results confounded by differential expectancies for relaxation. Furthermore, the role of expectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects of feedback delays and induced relaxation expectancies on EMG activity and experienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one of four computerized feedback delay conditions (0.0037, 0.7493, 2.2481, 6.7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affecting EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expectancies. Instrumental and expectancy factors in EMG biofeedback appear to operate independently of each other by reducing physiological activity and producing psychological relaxation respectively.This study was completed by the first author under the direction of the second author in partial fulfillment of the requirements for the Master of Arts degree. We gratefully acknowledge the computerization advice and assistance provided by Larry Wheeler, and the assistance in data collection provided by Dawn Dexter and Michael Winstanley.     

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.This research was supported by Grant 2 S06RR08038-17 funded by the National Institutes of Mental Health.