Blood glucose discrimination training in patients with Type II diabetes

This study was designed to determine whether patients with Type II diabetes could be taught to discriminate blood glucose after experiencing a variety of blood glucose levels and receiving feedback on the accuracy of their estimates. Thirty-six subjects (18 on oral agents and 18 on insulin) were randomly assigned to one of two feedback conditions: (1) current feedback, which received accurate information regarding their blood glucose levels, (2) noncurrent feedback, which received blood glucose levels from the preceding session. Subjects were exposed to a wide range of blood glucose values in six training sessions by ingesting drinks with three different caloric loads. In pre/post comparisons using several indices of accuracy, both groups showed significant improvement in estimating blood glucose levels. However, feedback on current blood glucose levels did not produce greater improvement than noncurrent. Accuracy was unrelated to the degree to which subjects reported associating internal sensations to their estimates. Failure to find differences between the two feedback conditions may have been due to the noncurrent feedback group's receiving fairly accurate information, to the difficulty of the discrimination task, and to the limited number of training trials.The authors thank Marsha D. Marcus, Ph.D., for her contributions to this study.     

Blood glucose discrimination training with insulin-dependent diabetics: a clinical note

Two insulin-dependent diabetic adults were exposed to a blood glucose discrimination training program. Following baseline, during which subjects estimated their blood glucose levels twice daily, subjects received immediate feedback regarding the accuracy of their estimates. The procedure resulted in a large increase in accuracy of blood glucose level estimation. The implications of the findings were discussed.     

Blood glucose discrimination training with insulin-dependent diabetics: A clinical note

Two insulin-dependent diabetic adults were exposed to a blood glucose discrimination training program. Following baseline, during which subjects estimated their blood glucose levels twice daily, subjects received immediate feedback regarding the accuracy of their estimates. The procedure resulted in a large increase in accuracy of blood glucose level estimation. The implications of the findings were discussed.The authors thank Joe Quattrini, Maria Bohnert, Jenifer Dale, Kathy Cogan, and Ruth Tarlow for their help in conducting this study. This research was supported in part by Grant AM 30840 from the National Institutes of Health.     

Blood glucose discrimination training in insulin-dependent diabetes mellitus (IDDM) patients

Self-management of insulin-dependent diabetes mellitus (IDDM) is dependent on a negative feedback loop of blood glucose (BG) fluctuations, which in turn directs treatment decisions to maintain normal BG. Although this feedback is typically accomplished by self-monitoring of blood glucose (SMBG), SMBG has limitations, and patients often rely on what their BG "feels" like. Two studies were performed to evaluate whether patients could learn to more accurately "feel"/discriminate their BG on the basis of internal cues or internal plus external BG cues. In Study I, BG Awareness Training significantly improved pre- to posttreatment BG estimation accuracy, relative to a control group. Study II replicated BG Awareness Training efficacy in improving BG estimation accuracy. Improvement in estimation accuracy was related only to initial accuracy; those who were initially less accurate improved the most. This improvement was represented in a 31% reduction in dangerous BG estimation errors and a 9% increase in accurate estimates. Resulting estimations were, however, still significantly less accurate than SMBG at the end of training.     

Accuracy of subjective blood glucose estimation by patients with insulin-dependent diabetes

A between-groups design using a baseline, treatment, follow-up procedure was used to investigate the accuracy of 20 patients with insulin-dependent diabetes when subjectively estimating their blood glucose levels. Patients were encouraged to attend to their mood for cues when making estimates of their blood glucose. Their capacity for reducing estimation errors when given immediate or delayed feedback of actual blood glucose was examined. The results showed that neither delayed nor immediate feedback produced a significant improvement in the mean estimation accuracy of these groups of patients or in their ability to predict whether their blood glucose was in the acceptable or unacceptable range. Patients were particularly inaccurate in detecting Low [less than 4.0 mmol/L (less than 72.0 mg/dl)] and Very High [greater than 16.0 mmol/L (greater than 288.0 mg/dl)] blood glucose levels. Examination of mood-blood glucose relationships revealed consistent patterns for individual subjects and considerable differences between subjects.     

Accuracy of subjective blood glucose estimation by patients with insulin-dependent diabetes

A between-groups design using a baseline, treatment, follow-up procedure was used to investigate the accuracy of 20 patients with insulin-dependent diabetes when subjectively estimating their blood glucose levels. Patients were encouraged to attend to their mood for cues when making estimates of their blood glucose. Their capacity for reducing estimation errors when given immediate or delayed feedback of actual blood glucose was examined. The results showed that neither delayed nor immediate feedback produced a significant improvement in the mean estimation accuracy of these groups of patients or in their ability to predict whether their blood glucose was in the acceptable or unacceptable range. Patients were particularly inaccurate in detecting Low [<4.0 mmol/L (<72.0 mg/dl)] and Very High [>16.0 mmol/L (>288.0 mg/dl)] blood glucose levels. Examination of moodblood glucose relationships revealed consistent patterns for individual subjects and considerable differences between subjects.The authors wish to thank the consultant physician Dr. J. D. Ward, and Drs. G. Knight and A. J. M. Boulton from the Royal Hallamshire Hospital, Sheffield, for referring the patients who took part in the study. The research was funded by NIH Grant number AM28196 to Dr. C. Bradley.     

Dicrimination of systolic blood pressure

The ability of humans to discriminate systolic blood pressure (BP) was investigated in two experiments. In Experiment 1, 14 normal subjects were asked to make estimates of their systolic BP while performing both BP-elevating and BP-lowering tasks. They were given intermittent feedback throughout all 10 45-min sessions. Results indicated significant correlations and small absolute differences between estimated and measured BP for all subjects in almost all sessions. Experiment 2, undertaken 6 months after Experiment 1, assessed whether estimation accuracy by subjects who had available both external and interoceptive cues surpassed that of subjects which access to external cues only. Three subjects from the original group who showed consistently high motivation, and who improved in accuracy across the 10 sessions in the previous experiment, made estimates of BP while performing novel tasks with no feedback. Correlations between estimated and measured BP remained high for 2 of the 3. These results were compared with the accuracy of control subjects (3 for each experimental subject) who were asked to estimate experimental subjects' BP using only the cognitive information available to the experimental subjects. Control subjects also had high correlations between their estimates and the experimental subjects' measured BP but at lower levels than two experimental subjects. These findings are discussed in relation to subjects' possible use of interoceptive information.     

Blood glucose discrimination training in insulin-dependent diabetes mellitus (IDDM) patients

Self-management of insulin-dependent diabetes mellitus (IDDM) is dependent on a negative feedback loop of blood glucose (BG) fluctuations, which in turn directs treatment decisions to maintain normal BG. Although this feedback is typically accomplished by self-monitoring of blood glucose (SMBG), SMBG has limitations, and patients often rely on what their BG feels like. Two studies were performed to evaluate whether patients could learn to more accurately feel/discriminate their BG on the basis of internal cues or internal plus external BG cues. In Study I, BG Awareness Training significantly improved pre- to posttreatment BG estimation accuracy, relative to a control group. Study II replicated BG Awareness Training efficacy in improving BG estimation accuracy. Improvement in estimation accuracy was related only to initial accuracy; those who were initially less accurate improved the most. This improvement was represented in a 31% reduction in dangerous BG estimation errors and a 9% increase in accurate estimates. Resulting estimations were, however, still significantly less accurate than SMBG at the end of training.This research was supported by NIH grants AM282880, AM24177, AM22125, and RR00847 and by the Ames Company. The authors express their appreciation for the contribution made by trainers Leslie Butterfield and Linda Zimbelman, by the nursing staff at the University of Virginia's Clinical Research Center and the Diabetes and Nutrition Unit, and by Dr. James May from the Medical College of Virginia in soliciting subjects. We would also like to thank Andrea Snyder for her assistance.     

The effect of feedback-assisted reduction in heart rate reactivity on videogame performance

In 67 male volunteers, we examined the reduction of cardiovascular responsivity to a psychomotor challenge (videogame) achieved by use of heart rate (HR) feedback and effects of these procedures on concomitant behavioral performance. Each subject participated in a pretraining assessment of his cardiovascular responses to the videogame, a training condition, and a posttraining assessment identical to the initial evaluation. During training, subjects were assigned to one of four conditions: (a) a habituation control group receiving no instructions to alter HR (HC); (b) an instructions-only control group receiving instructions to maintain a low or unchanged HR during videogame presentations (IC); (c) a feedback group receiving instructions to reduce HR using ongoing HR feedback (FB-); or (d) a feedback group receiving instructions to lower HR and given HR feedback plus a score contingency in which total game score was jointly determined by subjects' game performance and success at HR control (FB+). Subjects receiving feedback (FB+, FB-) exhibited greater reductions in HR response to the videogame in the posttraining assessment than control (HC, IC) subjects; FB+ subjects showed greater HR reductions than subjects in any other group. FB+ and FB- subjects showed a lower SBP at posttraining relative to the two control groups, but no reduction in task-induced blood pressure reactivity. There were no group differences in videogame performance, either before or following training.     

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 effect of feedback-assisted reduction in heart rate reactivity on videogame performance

In 67 male volunteers, we examined the reduction of cardiovascular responsivity to a psychomotor challenge (videogame) achieved by use of heart rate (HR) feedback and effects of these procedures on concomitant behavioral performance. Each subject participated in a pretraining assessment of his cardiovascular responses to the videogame, a training condition, and a posttraining assessment identical to the initial evaluation. During training, subjects were assigned to one of four conditions: (a) a habituation control group receiving no instructions to alter HR (HC); (b) an instructions-only control group receiving instructions to maintain a low or unchanged HR during videogame presentations (IC); (c) a feedback group receiving instructions to reduce HR using ongoing HR feedback (FB–); or (d) a feedback group receiving instructions to lower HR and given HR feedback plus a score contingency in which total game score was jointly determined by subjects' game performance and success at HR control (FB+). Subjects receiving feedback (FB+, FB–) exhibited greater reductions in HR response to the videogame in the posttraining assessment than control (HC, IC) subjects; FB+ subjects showed greater HR reductions than subjects in any other group. FB+ and FB– subjects showed a lower SBP at posttraining relative to the two control groups, but no reduction in task-induced blood pressure reactivity. There were no group differences in videogame performance, either before or following training.The authors wish to thank Fred Claus, who served as a research assistant for this study.     

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.     

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.     

Operant conditioning of skin resistance tonic levels

The purpose of the current investigation was to determine whether increases and decreases in skin resistance tonic level could be controlled by individuals given discrete visual feedback of such activity. Thirty-six male undergraduate students served as subjects. They were assigned randomly in equal numbers to four groups; two of the groups received accurate feedback of skin resistance level changes and two received inaccurate feedback. The two accurate-feedback groups differed with respect to the order in which increases and decreases in skin resistance level were reinforced. Each noncontingent group was matched with one of the contingent groups in terms of reinforcement density. The results indicated that accurate feedback produced skin resistance level changes consistent with the type of reinforcement employed. However, operant control was not clearly sustained subsequent to a reversal in the type of tonic level change reinforced. Some problems related to the clinical application of skin resistance level training are discussed.     

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.     

A comparison of direct blood pressure feedback and electromyographic feedback on the blood pressure of normotensives

Groups of 20 normotensive subjects were assigned to one of three conditions to help them lower their blood pressure: (1) intermittent visual feedback of blood pressure; (2) continuous analogue auditory feedback of frontal EMG; (3) an instructed, no-feedback condition. Both groups receiving feedback showed greater within-session lowering of systolic blood pressure than the no-feedback control group. Although the group receiving intermittent visual feedback of blood pressure lowered blood pressure more than the EMG feedback group at the first session, in three subsequent sessions, the two feedback groups did not differ.     

Operant conditioning of skin resistance tonic levels

The purpose of the current investigation was to determine whether increases and decreases in skin resistance tonic level could be controlled by individuals given discrete visual feedback of such activity. Thirty-six male undergraduate students served as subjects. They were assigned randomly in equal numbers to four groups; two of the groups received accurate feedback of skin resistance level changes and two received inaccurate feedback. The two accurate-feedback groups differed with respect to the order in which increases and decreases in skin resistance level were reinforced. Each noncontingent group was matched with one of the contingent groups in terms of reinforcement density. The results indicated that accurate feedback produced skin resistance level changes consistent with the type of reinforcement employed. However, operant control was not clearly sustained subsequent to a reversal in the type of tonic level change reinforced. Some problems related to the clinical application of skin resistance level training are discussed.Portions of this paper were presented at the meeting of the Midwestern Psychological Association, Chicago, 1973.     

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).     

Testing the accuracy of non-experts in biodiversity monitoring exercises using fern species richness in the Ecuadorian Amazon

Assessing environmental change is often constrained by time, money and expertise. Community-based monitoring schemes attempt to address these limitations by providing local communities with the skills to measure changes in natural resources and contribute locally relevant information for local and regional management decisions. Despite the increasing popularity of community-based monitoring schemes, there is little information about the accuracy of the data they produce. In this study we use visual guides and hands-on training to teach groups of leaders from local communities in the Ecuadorian Amazon to measure the species richness of ferns. We compare their results to data obtained by experienced field biologists and show strong positive correlations in species richness estimates between the results obtained by groups receiving visual guides, groups receiving hands-on training and biologists. Our results show that, even with relatively little training, communities can use simple and cost-effective methodologies to yield data that accurately reflect levels of species richness.     

Instructed heart rate control

Forty subjects participated in an experiment designed to test the effects of different feedback displays on instructed heart rate speeding and slowing. One group of subjects received information about interpulse interval length every beat. This display included specific information about when systole occurred, in addition to information about performance relative to a criterion. Two other groups received similar information about performance, but their displays were not triggered by systole; rather, information about average interpulse interval was presented either every second or every 6 seconds. A fourth group of subjects participated in a perceptual motor task in which no instructions were given to control heart rate.Results indicated that the instructed subjects generated significantly greater heart rate speeding than slowing. Groups receiving feedback produced greater changes when compared to the control group only during the speeding seassions. No differences among feedback groups were present in the slowing task. During speeding, the 1-second group's performance deteriorated dramatically in the second session. The results suggested that, in the context of a feedback task, it is information about the occurrence of systole that facilitates heart rate speeding. Real-time displays are less facilitating of heart rate change and may disrupt speeding performance when information is presented at certain critical frequencies. Slowing performance was again shown to be unrelated to information frequency or reinforcement rate.