Role of feedback in voluntary control of heart rate.

The relative effectiveness of biofeedback techniques on the voluntary control of heart rate was examined by randomly assigning 32 Ss to one of four feedback conditions in a bi-directional heart-rate control task: (1) no feedback, (2) binary feedback--S was signaled when an interbeat interval had changed in the correct direction, (3) "real-time," proportional feedback--S was provided information about the relative duration of successive interbeat intervals, and (4) numerical, proportional feedback--each interbeat interval was represented as a numeral indicating its relationship to pre-trial mean by direction and magnitude. Significant over-all heart-rate changes were evidenced for both increase and decrease directions, but no differences were found between the feedback conditions. While these data suggest that feedback may be a relatively insignificant factor in voluntary heart-rate control, it was recommended that further investigation examine the role of feedback within the context of other training, mediating and motivational variables.     

Contact-free measurement of heart rate, respiration rate, and body movements during sleep

We describe a noncontact method for the ambulant measurement of basic sleep physiology parameters in humans, particularly for field studies involving sleep research and sleep disturbances. This method traces the body movements, respiration, and heart action of a person at rest or asleep on a bed, using four high-resolution force sensors installed under the bedposts. The recoil movement of the body at each heartbeat, known as the cardioballistic effect, as well as the lifting and lowering of the thorax, while breathing, causes very small shifts of the center of gravity of the bed and the subject. These shifts are reflected in the altering force distributions across the four sensors. Cardiac and respiratory parameters and the subject’s movement activity can be calculated from the sensor signals. Neither electrodes nor other kinds of transducers are in direct contact with the subject, which is the main advantage of this technique over conventional methods. Laboratory experiments were carried out to estimate validity and practicability. The method has been found to be adequate, especially for automated and unattended sleep-data collection over long periods of time.     

Developmental change in feedback processing as reflected by phasic heart rate changes

Heart rate was recorded from 3 age groups (8-10, 12, and 20-26 years) while they performed a probabilistic learning task. Stimuli had to be sorted by pressing a left versus right key, followed by positive or negative feedback. Adult heart rate slowed following negative feedback when stimuli were consistently mapped onto the left or right key (response-dependent condition) but not when responses to stimuli were always followed by negative feedback (uninformative condition). Young children's heart rate showed slowing following both response-dependent and uninformative negative feedback. These findings suggest that the ability to assess the relevance of performance feedback improves with age, resulting in improved adjustment to dynamical changes in the task environment.     

Opportunity for information search and the effect of false heart rate feedback

The role of information search in the attribution of physiological states was investigated by manipulating the subject’s opportunity for information search following the presentation of false information about his heart-rate reactions to photographs of female nudes. Consistent with the self-persuasion hypothesis proposed by Valins, the rated attractiveness of the slides was not affected by the false heart-rate feedback for those subjects who were prevented from visually searching the slides. Those subjects who had ample opportunity to view the slides rated those slides accompanied by false information of a heart-rate change as more attractive than those slides which were not paired with a change in heart rate.     

Emotional responsivity to nonveridical heart rate feedback as a function of anxiety

The purpose of the present investigation was to examine the effects of nonveridical heart rate feedback and anxiety on electrodermal responses and verbal reports to emotionally laden stimuli. Forty-eight female subjects were divided into high and low anxious groups on the basis of their Taylor Manifest Anxiety Scale scores and resting level electrodermal activity. All subjects viewed 10 autopsy slides while hearing continuous auditory tones supposedly representing their own heartbeats. Twenty-four subjects heard the tones increase in rate with slide onset. The other 24 subjects heard no change in rate with slide onset. The high resting autonomic activity group responded with significantly larger electrodermal responses to the heart rate feedback-slide combination than the low resting level autonomic activity group. The high autonomic activity group also reported that the slides were significantly more unpleasant than the low autonomic activity group, particularly those slides accompanied by an increase in heart rate feedback. Implications of these findings for a cognitive-visceral model of emotion are discussed.     

Associations between heart rate,perceived heart rate,and anxiety during acute psychological stress

ABSTRACT

Background: Acute psychological stress elicits increases in heart rate (HR) and anxiety. Theories propose associations between HR, perceived HR, and anxiety during stress. However, anxiety is often measured as a unidimensional construct which limits a comprehensive understanding of these relationships.

Objectives: This research explored whether HR reactivity or perceived HR change was more closely associated with cognitive and somatic anxiety during acute psychological stress.

Design: Two laboratory-based studies were conducted.

Methods: In a single laboratory session, healthy male (N?=?71; study 1) and female (N?=?70; study 2) university students completed three laboratory psychological stress tasks (counterbalanced), each with a preceding baseline. Heart rate, perceived HR change, and cognitive and somatic anxiety intensity and interpretation of anxiety symptoms were assessed immediately following each task. Data were aggregated across tasks.

Results: Actual HR change was unrelated to anxiety intensity, but was associated with more debilitative interpretations of anxiety (study 2). Perceptions of HR change were consistently associated with greater intensity of cognitive (study 1) and somatic (study 1 and 2) anxiety.

Conclusions: Perceived HR rather than actual HR is more closely associated with anxiety intensity during psychological stress. The findings have implications for stress management and the clinical treatment of anxiety symptoms.     

Public and private heart rate feedback in social phobia: a manipulation of anxiety visibility

According to cognitive behavioural models of social phobia, bodily symptoms are the main source of information concerning social evaluation for social phobics. Experience and perception of bodily symptoms therefore play an important role in social anxiety. In this study we evaluated the effects of anxiety visibility on patients and controls using feedback of veridical heart sounds. A total of 32 social phobics and 32 controls were asked twice to sit in a chair and appear relaxed while being evaluated. Half of the participants heard their heart sounds first via headphones and then via loudspeakers which were also audible to observers. The presentation order of the heart sound was reversed for the other half of the subjects. Social phobics reported substantially more anxiety than controls. Both groups showed habituation in heart rate from the first to the second presentation, and both groups reported perception of a higher heart rate, but only social phobics reported significantly more anxiety and were more worried about their heart rates in the public than in the private condition. These effects were in excess of actual heart rate differences. In conclusion, social phobics worried about the broadcast of a bodily anxiety symptom, whereas controls did not. Information about arousal made public has a strong potential to increase anxiety levels in social phobics.     

Anxiety, perception, and control of heart rate

8 women and 8 men took Cattell's IPAT-anxiety questionnaire and later McFarland's test of ability to perceive heart activity. The second test involved subjects' tracking their own heart rates, then they enrolled in an EKG biofeedback session to evaluate ability to increase and decrease heart rate from subjects' resting baselines. At the end of the session each subject completed Blanchard, et al.'s questionnaire to specify the cognitive strategies used for heart-rate control. Heart rate, abdominal respiration rate, respiration amplitude, EEG percent power in theta, alpha, and beta bands were evaluated. Success of heart-rate decrease seemed to depend mainly on activity levels: the subjects who achieved high scores on the activity test decreased heart rate significantly better than did low scorers. The relationship between scores for perception of heart and increases in heart rate was nonsignificant: increased heart-rate seemed to depend on differences in respiration between the rest and periods of increase. The significant, negative correlation between trait anxiety and perceptions of heart activity suggested that anxiety affected subjects' ability to perceive heart rate. The theta EEG power of the right hemisphere was significantly higher in subjects scoring high than for those low in perception of heart activity. During heart-rate increase tasks subjects mainly reported use of 'arousal responses,' similarly during heart-rate decrease tasks they reported use of relaxation responses.     

Awareness of the response after feedback training for changes in heart rate and sudomotor laterality

What is the relation between the ability to control visceral responding on a biofeedback task and the ability to report behaviors actually contributing to this performance? Subjects received biofeedback training for unidentified visceral responses and then gave written reports about what they had done to control the feedback displays. Independent judges were given these reports and, on the basis of knowledge about activities known to contribute to visceral activity, were asked to determine the visceral responses for which the subjects had been trained. The reports of subjects who succeeded at bidirectional control of heart rate (Experiment 1) or sudomotor laterality (Experiment 2) showed awareness of behaviors related to feedback as assessed by this procedure, whereas the reports of subjects who failed at bidirectional control did not. Subsequent experiments indicated that these results did not depend on a learning strategy that might have been specific to the initial studies. These findings call into question the view that people are unaware of what they have done to produce the response after training on biofeedback tasks. Earlier studies reporting lack of awareness in biofeedback are discussed in light of factors that affect the measurement of biofeedback learning and response awareness.     

Public and private heart rate feedback in social phobia: a manipulation of anxiety visibility

According to cognitive behavioural models of social phobia, bodily symptoms are the main source of information concerning social evaluation for social phobics. Experience and perception of bodily symptoms therefore play an important role in social anxiety. In this study we evaluated the effects of anxiety visibility on patients and controls using feedback of veridical heart sounds. A total of 32 social phobics and 32 controls were asked twice to sit in a chair and appear relaxed while being evaluated. Half of the participants heard their heart sounds first via headphones and then via loudspeakers which were also audible to observers. The presentation order of the heart sound was reversed for the other half of the subjects. Social phobics reported substantially more anxiety than controls. Both groups showed habituation in heart rate from the first to the second presentation, and both groups reported perception of a higher heart rate, but only social phobics reported significantly more anxiety and were more worried about their heart rates in the public than in the private condition. These effects were in excess of actual heart rate differences. In conclusion, social phobics worried about the broadcast of a bodily anxiety symptom, whereas controls did not. Information about arousal made public has a strong potential to increase anxiety levels in social phobics.     

Individual differences in imagery vividness and voluntary heart rate control

Dispositional differences in imagery vividness may account partially for the large individual differences in learning heart rate control. Based upon scores on the Betts QMI Vividness of Imagery Scale, 10 subjects were defined as a high imagery group and 10 subjects were defined as a low imagery group. All subjects were instructed to try to alter their heart rate as indicated by appropriately labeled lights. Six increasing, six decreasing and six rest, 45-sec trials were presented. During the trials, visual heart rate feedback was provided by a digital voltmeter. The dependent measure was computed by subtracting the mean of the last 5 beats of a 15-sec intertrial interval from the mean rate per trial. Results indicated that subjects were able to significantly raise and lower heart rate relative to rest trials. Furthermore, high imagery subjects demonstrated significantly larger changes than low imagery subjects on increase trials but not on decrease trials. Subjects in both groups typically reported using more specific images for increasing heart rate than for decreasing heart rate. These data suggest that dispositional differences in imagery vividness may have contributed to the differential performance of the two groups during the increase task.