Evidence of a Role for Response Plans and Self-Monitoring in Biofeedback

Subjects in a control group were given feedback training for two unidentified visceral responses (increases and decreases in heart rate) and were then asked to provide a verbal report describing what they had done to control the feedback displays. Judges were given these reports and asked to determine training condition (increase heart rate on A trials and decrease heart rate on B trials, or the reverse) from them. Subjects in an experimental group received the same procedure but were also asked for a verbal report prior to receiving their first feedback display and thenceforth after each of the first 10 trials of feedback training. The results showed that: a) success at biofeedback learning is accompanied by verbal awareness of activities contributing to response production, and b) learning can be predicted (r= .80) by probing the subject's problem space before he has seen his first feedback trial. Extensive verbal probing of experimental subjects did not eventuate in superior learning in this group. The nature and role of problem-solving activity in biofeedback are discussed.     

Cognitive and Somatic Events Associated With Discriminative Changes in Heart Rate

In Experiment 1, 23 males were given instructions to think about anxiety-provoking cognitive events (n= 12) or relaxing cognitive events (n= 11) during 20 30-sec training trials. Significant pretrial-to-trial increases in heart rate were noted during anxiety instructions and significant pretrial-to-trial decreases in heart rate were detected during relaxation instructions. In Experiment 2,39 males were again given instructions to think about anxiety-provoking events (n= 19) or relaxing events (n= 20) during 20 30-sec training trials. In addition, half of the subjects in each of these instructional conditions were given digital heart rate feedback consistent with their instructions (e.g., were reinforced for heart rate increases during anxiety instructions), whereas half of the subjects in each instructional condition were given feedback inconsistent with their instructions (e.g., were reinforced for heart rate decreases during anxiety instructions). As in Experiment 1, significant pretrial-to-trial increases in heart rate occurred during anxiety instructions and significant pretrial-to-trial decreases in heart rate were noted during relaxation instructions. The type of feedback which subjects received had no effect on the heart rate changes. The heart rate changes in both experiments were generally accompanied by parallel changes in respiratory rate but not by changes in chin muscle tension. It appears that cognitive events can produce increases and decreases in heart rate which are comparable in magnitude to those noted during biofeedback.     

Effect of Feedback Sensitivity Upon Learned Heart Rate Acceleration

Twelve undergraduate volunteers received 12 sessions of heart rate biofeedback training involving one of two experimental conditions. One-half of the subjects received 4 sessions of high sensitivity analogue heart rate biofeedback, followed by 4 sessions of low sensitivity feedback, and then, 4 final sessions of high sensitivity feedback. The other half of the subjects received the exact opposite order of feedback conditions. All subjects were instructed to accelerate heart rate during 8 trials in each session. The results were contrary to the hypothesis derived from a motor skills model of visceral learning, i.e., the low feedback sensitivity condition consistently produced larger magnitude heart rate acceleration in comparison to the high sensitivity condition. These findings were discussed in terms of methodological suggestions for future research and in terms of the motor skills model of visceral learning.     

Acquisition of the control of a novel muscular activity by electromyograph biofeedback

Present study aimed at to examine the process that people acquire the control of a novel muscular activity, of which they have had little experience of voluntary control, by electromyograph (EMG) biofeedback. Thirty undergraduate students who were unable to move their ears served as subjects. They were asked to give tension unto the m. auricularis posterior (the muscle to draw an ear backward). A factorial design was employed with two levels of strategy (transferring, non-transferring) and three methods of how to provide with the EMG feedback signals from the m. auricularis posterior during training session (no-feedback, biofeedback, intermittent biofeedback). The experiment was consisted of four sessions: rest, pre-test, training, and post-test. Main results were as follows: (1) Two groups, which subjects used the transferring strategy and the feedback signals, significantly increased the integrated EMG of the m. auricuralis posterior from pre- to post-tests. (2) Furthermore, the EMG-increase was significantly greater in one group, which feedback signals were intermittently given at every other training trial, than another group, which feedback signals were given at all trials. (3) It was also found that no increase of awareness to the muscular tension occurred despite the increase of EMG activity.     

Heart Rate Biofeedback and Cold Pressor Pain

This study addressed the relative contributions of self-regulated heart rate change and belief that heart rate is changing in an instructed direction to the perception of cold pressor pain. Forty male volunteers were each assigned to one of four combinations of increase or decrease heart rate instructions and increase or decrease feedback conditions. Subjects were given an initial 45-sec cold pressor test, 25 feedback trials, and a final cold pressor in which they were told to change their heart rate in the instructed direction, but without the aid of feedback. Subjects were instructed specifically that increased heart rate was associated with increased pain and decreased heart rate with decreased pain. The veridical groups (consistent instructions and feedback) showed appropriate heart rate changes during biofeedback training and parallel changes in heart rate and pain perception during the final cold pressor. The non-veridical (reverse) feedback groups showed no heart rate change during biofeedback training and no relationship between heart rate and pain perception changes during the final cold pressor test. EMG, respiration, and skin conductance data are presented, and several mechanisms are proposed to explain the physiological and subjective changes.     

The Effects of Feedback Sensory Modality, Feedback Information Content, and Sex on Short-Term Biofeedback Training of Three Responses

In three factorial experiments, auditory vs visual vs tactile feedback, analog feedback vs analog feedback which was anchored, and sex, were varied to assess the effects of these variables on performance in short-term biofeedback training of heart rate reduction, hand temperature increase, and forehead muscle tension reduction. A total of 108 subjects served in the study. Moderate but reliable changes were found during the course of the training session for all three physiological responses. The ability to reduce heart rate in a single training session did not appear to be a function of any of the variables manipulated in this study, but rather could be attributed to adaptation. In both muscle tension and temperature training, however, there were significant interactions between sex and sensory modality of the feedback stimulus and, in the case of muscle tension training, between information content of the feedback signal and sex. The overall pattern of results indicated that performance during biofeedback training is a complicated function of sex and the type of signal used to provide feedback, and that this function is not constant across physiological response systems.     

The Effects of Slow Cortical Potentials on Response Speed

The relationship between slow cortical potentials (SCPs) and response speed was investigated by training subjects to induce different cortical shifts by means of a biofeedback procedure. During two identical experimental sessions trials with visual feedback of the actual DC-shifts alternated with reaction time trials without feedback. In reaction time trials only the signal for the required change in polarity was provided. At the end of the signal interval an immediate button-press was required to stop a hissing noise. Two groups of 10 subjects each were investigated, one group receiving feed back from the left precentral recording(C₃) and the other from the right precentral recording (C₄). Results showed that subjects achieved control over their SCPs. At the end of the training period in the second session significant differences in SCPs between trials of the different required polarities were observed, during feedback trials as well as during reaction time trials without feedback. Subjects responded faster during trials in which a change toward more cortical negativity was required as compared to trials requiring less negativity.     

Voluntary Control of Systolic Blood Pressure During Postural Change

The effects of biofeedback and voluntary control procedures on systolic blood pressure and heart rate during postural change were investigated in 30 normotensive men. Systolic pressure was measured with a continuous blood pressure tracking cuff, and blood pressure feedback was provided on a beat-to-beat basis. Postural changes in pressure, and corresponding heart rate changes, were examined in three experimental groups (N = 10 each). In two groups, subjects were given feedback training to increase or to decrease systolic blood pressure. In the third group, subjects were simply asked to increase their pressure but were not given feedback about their performance. Voluntary control of systolic pressure was attempted while subjects were seated and during postural change—sitting to standing. Subjects were also instructed to maintain voluntary blood pressure control in subsequent no-feedback test trials. During postural change, voluntary control procedures caused significant alterations in tonic levels of systolic pressure, but phasic blood pressure reactivity was unaffected. With respect to postural changes in heart rate, both tonic and phasic treatment effects were observed. Implications of the findings for basic and clinical research are discussed.     

Cardiac-Respiratory-Somatic Relationships and Feedback Effects in a Multiple Session Heart Rate Control Experiment

An experiment addressing several unresolved issues in operant conditioning of heart rate (HR) in human subjects was performed. Cardiac-respiratory relationships, cardiac-somatic relationships, effects of biofeedback, and individual differences were examined in terms of their stability across multiple training sessions. Thirty subjects participated in 3 training sessions. Each session began with 4 trials of attempted HR change without feedback followed by 8 trials with “proportional” feedback of HR. On half the trials HR decrease was attempted while HR increase was attempted on the other half. Subjects were instructed to keep their respiration rate (RR) constant and not to engage in undue movement or muscle activity. Results indicated that subjects were able to produce significant HR increases and decreases from baseline levels, but these changes were accompanied by parallel changes in respiratory and somatic variables which persisted across sessions. Analysis of data from individual subjects was performed to explore the nature of individual differences in cardiac-respiratory-somatic patterns. The effects of biofeedback were unimpressive, suggesting at best a minor improvement in cardiac control with increased respiratory concomitance. Cardiac control, feedback effects, and cardiac-somatic patterns were stable over sessions. There was evidence of some reduction in cardiac-respiratory parallelism across sessions.     

Voluntary Heart Rate Control as a Function of Individual Differences in Electrodermal Lability

Twenty-four male subjects were run in a paradigm in which they were first asked to rest for 10 min and then given 20 1-min training trials of analog and digital feedback of their heart rate, with instructions to increase the rate. Subjects were rewarded with 0.2 cents for each interbeat interval that was faster than a designated criterion. Subjects were subdivided into “labile” and “stabile” groups on the basis of frequency of spontaneous skin conductance fluctuations during the baseline period. Mean heart rate for the training trials was compared with the baseline period for the most labile and most stabile subjects. Results indicated that there was a significant treatment effect for stabile subjects only, but not for labile subjects.     

Biofeedback of baroreflex sensitivity in patients with mild essential hypertension

An attempt was made to reduce blood pressure by increasing the baroreflex sensitivity (BRS) via biofeedback. Six patients with mild essential hypertension and 5 normotensive participants were studied during 8 biofeedback sessions. Each session consisted of 5 trials, 5 min each. The first and the last trials served as baselines of heart rate, blood pressure, respiration, and BRS. During the3 middle trials the BRS was calculated online using the sequencing technique. The resulting value was used as a visual analogue feedback signal. Participants were asked to increase BRS. The mean BRS was 8.3 [ms/mmHg] for the hypertensive patients and 12.2 [ms/mmHg] for the normotensive participants. During biofeedback trials as well as across sessions neither the hypertensive nor the normotensive group showed a statistically significant increase of BRS, only heart rate variability increased significantly. Contrary to expectation blood pressure increased in both groups. One hypertensive subject made significant progress during the training by performing valsalva maneuvers. The data show that BRS is reduced in hypertensive subjects. The increase of the heart rate variability could be a sign of the activation of the baroreflex although the BRS itself did not increase. Despite the successful technical and organizational im plementation of this biofeedback approach, it was not effective to systematically reduce blood pressure. A further development in the direction of guiding the patient to use the valsalva breathing pattern and/or a prolonged duration of the biofeedback training might be promising.     

Electromyograph Biofeedback: Generalization and the Relative Effects of Feedback, Instructions, and Adaptation

The present research describes two experiments. The first experiment examined training conditions designed to enhance generalization during electromyograph (EMG) biofeedback. Twelve female and 12 male subjects were randomly assigned to one of four conditions: frontalis EMG biofeedback; frontalis, forearm extensor and masseter biofeedback; frontalis, forearm extensor and semispinalis/splenius biofeedback; and a no-feedback (instructions only) condition. EMG and heart rate were monitored during 3 training sessions. Although reliable decreases in EMG and heart rate were obtained, no differential effect of single- versus multiple-muscle biofeedback was observed; nor, indeed, were differences between biofeedback and no-feedback apparent. A second experiment was conducted to determine whether EMG and heart rate reductions reflected a general relaxation response or were simply due to the effects of adaptation. Twenty-four female subjects were randomly assigned to either a frontalis EMG biofeedback, a no-feedback or an adaptation control condition. Results indicated that decreases in frontalis EMG levels were due to the instructions to relax whereas heart rate decreases were attributable to adaptation. Equivalence between biofeedback and no-feedback conditions was again apparent. It was concluded that this finding raises serious questions about the presumed critical role of the feedback signal in EMG biofeedback.     

Cardiac Response to Speech Sounds in Preterm Infants: Effects of Postnatal Illness at Three Months

The effect of postnatal illness, specifically respiratory distress syndrome (RDS), on preterm infants’ attention to auditory stimuli at 3 months of age was examined in three groups of infants; healthy preterm, preterms who had RDS, and a sample of normal term infants. Infants were presented 2 sessions of 9 trials of synthesized consonant-vowel sounds. The first 7 trials consisted of a binaural presentation in which the CV stimulus /ba/ or /pa/ was presented simultaneously to both left and right ears. The eighth and ninth trials consisted of a dichotic presentation in which the speech stimuli /ba/ and /pa/ were presented, one sound to the left ear and one sound to the right ear. EKG was recorded throughout the presentation. Analyses of covariance with prestimulus heart period as the covariate and heart period during stimulus presentation as the dependent measure were computed to investigate cardiac orienting, habituation and recovery. Results reveal significant cardiac orienting by healthy term and preterm infants on trial 1, habituation across trials 1–7, and recovery of cardiac orienting to stimulus change on the second novel presentation by healthy term and preterm. RDS preterm infants exhibited cardiac orienting to the first stimulus presentation but they did not evidence a change in cardiac level across redundant trials or a response recovery to the novel stimulus. RDS preterms throughout exhibited shorter heart period levels (faster heart rates) than either healthy term or healthy preterm infants. Results are discussed in relation to the effect of RDS on autonomic reactivity.     

Training and Transfer of Training Effects in EMG Biofeedback Assisted Muscular Relaxation

Twenty-two normal adults participated in an electromyographic (EMG) biofeedback experiment designed to test if the feedback stimulus is necessary in obtaining EMG reductions during typical laboratory procedures, and if prior training on one muscle facilitates the training of a second muscle. One group of subjects received forearm feedback training followed by frontalis training. A second group received training in the reverse order. Two control groups relaxed first on their own followed by either forearm or frontalis training. Attention was directed toward motivating control subjects to perform maximally during relaxation without feedback. Heart and respiration rates and skin conductance and temperature were also recorded. Both trained and untrained subjects produced significant EMG reductions but did not differ from each other; nor did a transfer of training effect emerge. No differences resulted between feedback and non-feedback conditions for the other physiological measures or for changes in state anxiety. These data compromise somewhat the previous demonstrations of EMG biofeedback “learning,” and are unsupportive of EMG biofeedback as a general relaxation training technique.     

The effect of chronic anxiety level upon self control of heart rate

A sample of 90 subjects were rated on the IPAT anxiety scale and 5 subjects (3 male and 2 female) per group were selected from each of the high and low anxiety categories. All subjects were naive participants in heart rate biofeedback sessions utilising analogue visual feedback. Following a heart rate baseline (no feedback) session, all subjects were required to raise their heart rate and lower their heart rate in two separate trials, a visual ‘target’ criteria being provided. The data collected consisted of a resting baseline heart rate value, mean heart rate increase, and mean heart decrease values expressed as beats per minute. Results indicated a marked ability for highly anxious subjects to self-induce heart rate increases only and for low anxious subjects to decrease their heart rate only.     

Electroencephalographic and reaction time asymmetries to musical chord stimuli

EEG was recorded over left and right hemispheres at temporal leads (T3, T4) referred to the vertex (Cz) in 16 right-handed male subjects. Musical chords were presented randomly in monaural sequence, during a task which required a selective motor response to stimuli presented to one ear. The integrated amplitude of the 8-13 Hz alpha rhythm was measured when subjects listened passively. Under all conditions, a lower mean alpha amplitude was recorded over the right hemisphere than the left, regardless of which ear was stimulated. Alpha suppression over the right temporal area was accentuated when the performance task directed attention to the stimulus. Reaction time to left ear stimulation was shorter than that for the right ear. With monaural stimulus presentation behavioral asymmetry, and various EEG asymmetries can be observed. There is hemispheric asymmetry associated with attention to task relevant stimuli indicated by reduction in the alpha rhythm over the right temporal area and asymmetry in reaction time with greater efficiency of the left ear to muscial chords.     

Perception of Gastric Contractions and Self-Control of Gastric Motility

The hypothesis was that self-control of a visceral response is dependent on ability to perceive occurrence of the response. Subjects were asked to judge whether or not a signal light coincided with a stomach contraction on each of approximately 200 trials. In a different session heart beat perception was tested by asking subjects to judge whether or not signal light flashes coincided with heart beats. Subjects then were tested for ability to increase and to decrease gastric motility prior to biofeedback training, after which half received 4 hrs of visual feedback while the others practiced without feedback. Control of motility without feedback was subsequently retested. Initially, subjects were unable to control gastric motility, but with feedback they could increase motility on command. Ability to perceive gastric contractions was unrelated to control of gastric motility before, during, or following biofeedback training, indicating that self-control of a visceral response is not dependent on perceptual sensitivity. Perception of stomach contractions correlated significantly (r= .51) with perception of heart beats, suggesting that there may be a generalized tendency to be aware of or to attend to visceral events.     

Instructed heart rate control in a high heart rate population

Forty college students were selected from a large number of introductory psychology students on the basis of high heart rate during an initial screening session. Subjects were then contacted and participated in two additional sessions during which heart rate, respiration rate, and skin conductance measures were obtained. Each session consisted of a baseline period followed by five trial periods during which subjects attempted to control their heart rate or performed a visual tracking task. Subjects were randomly assigned to one of four groups. One group served as a control and monitored a visual feedback display driven by their own heart rate but received no instructions to decrease their heart rate. In contrast, the three heart rate control groups were instructed to decrease heart rate during the trial periods by utilizing a relaxation procedure, proportional biofeedback, or proportional biofeedback plus criterion information. No group differences were present during the baseline periods. During feedback trials, however, all the training groups differed from the control in heart rate but did not differ from each other. It is suggested that feedback displays may not facilitate heart rate reduction beyond the level achieved by instructing subjects to use a general relaxation procedure.     

Quantitative Measurements of Finger Blood Flow During Behavioral Treatments for Raynaud''s Disease

Quantitative measurements of finger blood flow have not been performed during temperature biofeedback or other treatments for Raynaud's disease. In the present investigation, finger blood flow was determined with venous occlusion plethysmography, in addition to measurements of finger temperature, heart rate, blood pressure, and skin conductance level. After a maximum vasodilation test, subjects received 10 sessions of finger temperature biofeedback or autogenic training. There were no group differences during the maximum vasodilation test. During training, temperature feedback subjects showed significant elevations in finger blood flow, finger temperature, and skin conductance level, whereas those who received autogenic training did not. These findings could not be explained by group differences in other cardiovascular measures and are consistent with previous studies suggesting the involvement of an active vasodilating mechanism in temperature feedback.     

Cardiac concomitants of feedback processing

This study examined the heart rate changes associated with positive and negative performance feedback in a probabilistic learning task derived from Holroyd and Coles (Psychological Review, 109 (2002) 679). In this task, subjects were presented with six stimuli and asked to respond by pressing a left versus right key. Responses were followed by positive or negative feedback. Subjects had to infer the S-R mapping rule on the basis of feedback provided to them. Two stimuli were consistently mapped onto the left versus right key (100% mapping). Two other stimuli were randomly mapped onto the keys (50% mapping) and responses to the two remaining stimuli received always positive or negative feedback (always condition). Negative feedback was associated with heart rate slowing in the 100% condition. Heart rate slowed following both positive and negative feedback in the 50% condition, but only when the previous encounter with the stimulus was followed by alternate feedback. Heart rate did not differentiate between positive and negative feedback in the always condition. The results were interpreted in support of the hypothesis assuming that heart rate slowing is elicited when performance-based expectations are violated.