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PubMed1997

Maximizing performance feedback effectiveness through videotape replay and a self-controlled learning environment.

This study was designed to examine whether participants who could control the schedule of performance feedback (KP) would learn differentially from those who received a rigid feedback schedule while learning a complex task. Participants (N = 48) were randomly assigned to self-controlled KP (SELF), summary KP (SUMMARY), yoked control (YOKE), or knowledge of results only (KR) conditions. Data collection consisted of an acquisition phase and a 4-day retention phase during which right-handed participants performed a left-handed ball throw. Overall, throwing form improved across trial blocks during acquisition, with the SUMMARY, SELF, and YOKE groups showing more improvement than the KR group. During retention, the SELF group retained a higher level of throwing form and accuracy in comparison to the other groups. Results suggest that when given the opportunity to control the feedback environment, learners require relatively less feedback to acquire skills and retain those skills at a level equivalent to or surpassing those who are given more feedback but receive it passively.

Biofeedback, Psychology↗
PubMedDate not supplied

Maximizing the motivational impact of feedback of lung cancer susceptibility on smokers' desire to quit.

This two-by-two factorially designed study evaluate approaches for communicating feedback of lung cancer susceptibility to smokers as a method for motivating smoking cessation. The study factors were: method of communicating feedback (by mail with telephone follow-up or in-person) and carbon monoxide feedback (yes or no). One-hundred-forty-four smokers were stratified on race and randomized to one of four conditions. Participants were surveyed at baseline and 2-month follow-up. Polymerase chain reaction (PCR) testing for the absence of the glutathione S transferase mu (GSTM1) gene was the susceptibility marker. Regardless of counseling method or carbon monoxide (CO) feedback, the majority (90%) of smokers accurately recalled the test result and 66% accurately interpreted the meaning of the test result. Smokers who received their result in person were significantly less likely to have read the result booklet than those in the telephone counseling group (OR = .28, 95%; CI .12-.62; p < .05). Neither counseling method nor CO feedback increased smokers' perceived risks for lung cancer. However, at the counseling session those who received in-person counseling were significantly less frightened by the test result than those who received telephone counseling (OR = .42, 95%; CI .20-86; p < .05) and at the 2-month follow-up those who received a CO test were significantly less frightened by their susceptibility result (OR = .40, 95%; CI .17-.92; p < .05) than those who did not have a CO test. Evaluation of further refinements in communicating the meaning of susceptibility results to motivate smoking cessation is warranted.

Adult↗
PubMed1992

Transfection of nonmuscle beta- and gamma-actin genes into myoblasts elicits different feedback regulatory responses from endogenous actin genes.

We have examined the role of feedback-regulation in the expression of the nonmuscle actin genes. C2 mouse myoblasts were transfected with the human beta- and gamma-actin genes. In gamma-actin transfectants we found that the total actin mRNA and protein pools remained unchanged. Increasing levels of human gamma-actin expression resulted in a progressive down-regulation of mouse beta- and gamma-actin mRNAs. Transfection of the beta-actin gene resulted in an increase in the total actin mRNA and protein pools and induced an increase in the levels of mouse beta-actin mRNA. In contrast, transfection of a beta-actin gene carrying a single-point mutation (beta sm) produced a feedback-regulatory response similar to that of the gamma-actin gene. Expression of a beta-actin gene encoding an unstable actin protein had no impact on the endogenous mouse actin genes. This suggests that the nature of the encoded actin protein determines the feedback-regulatory response of the mouse genes. The role of the actin cytoskeleton in mediating this feedback-regulation was evaluated by disruption of the actin network with Cytochalasin D. We found that treatment with Cytochalasin D abolished the down-regulation of mouse gamma-actin in both the gamma- and beta sm-actin transfectants. In contrast, a similar level of increase was observed for the mouse beta-actin mRNA in both control and transfected cells. These experiments suggest that the down-regulation of mouse gamma-actin mRNA is dependent on the organization of the actin cytoskeleton. In addition, the mechanism responsible for the down-regulation of beta-actin may be distinct from that governing gamma-actin. We conclude that actin feedback-regulation provides a biochemical assay for differences between the two nonmuscle actin genes.

Actin Cytoskeleton↗
PubMed1999

Human factors in telesurgery: effects of time delay and asynchrony in video and control feedback with local manipulative assistance.

This paper presents the results of experiments examining the performance of a telesurgeon and an assistant local to the patient performing simulated laparoscopic tasks under a variety of time-delay conditions. Of particular interest is a comparison between the surgeon provided with audio/video and force feedbck synchronously with various time delays, and the surgeon performing asynchronously, where video is delayed relative to force feedback. These conditions are relevant since current telecommunication systems have limited bandwidth, and video signals must be compressed for efficient transmission. This produces a time lag between the video camera and the surgeon's monitor, Force feedback and position commands from a surgical teleoperator require much lower bandwidth, and can be transmitted in near-real time. In the first of two series of experiments, two laparoscopic training tasks were performed under different time-delay conditions, with force and video feedback delayed by equal amounts. In the second series, using the same tasks, the force feedback was more immediate, while the video delay lagged by the time required for compression and decompression. In both experiments, there were various role assignments in terms of whether the telesurgeon or the assistant controlled the laparoscope and/or the various surgical tools required. The three most striking results are that (1) nontrivial time delays significantly degraded the performance of the surgical tasks, (2) asynchronous force feedback resulted in significantly faster task-performance than did synchronous performance when the surgeon operated the laparoscopic tools, and (3) there was no difference between synchrony and asynchrony when the remote surgeon operated the laparoscope and gave commands while the local assistant operated the surgical tools.

Humans↗
PubMed1986

Visually displayed EMG feedback: single case studies of hemiplegic upper extremity rehabilitation.

The efficacy of visually displayed EMG feedback in treating hemiplegic upper limb motor disorders was investigated in 5 patients (0.5-4 years poststroke). A single case experimental method "multiple-baseline across target behaviors" was used to compare performance during the feedback phase to that occurring in the monitored baseline phase. The nonfeedback baseline phase was followed by the staggered introduction of audiovisual feedback for each of the targeted pairs of muscles. EMG feedback obtained from muscle pairs (shoulder: anterior deltoid and upper trapezius; elbow: brachial triceps and biceps; digits: extensor digitorum communis and digit flexors) was displayed as two distinct waveforms on a videomonitor during therapy. Nonfeedback assessment of each of the three pairs was performed during each session. The effects of feedback were not uniformly distributed. Elbow control responded best, and statistical tests confirmed the effects of intervention observed clinically in all 5 patients. Clinical improvements in shoulder flexion were observed in 4 patients but could be statistically attributed to EMG gains in just 1. Improvement in finger extension observed clinically in 3 patients was statistically attributable to EMG gains in 2. All patients regained control of at least one target activity. EMG gains were accompanied by increases in active range of motion and by varying functional improvement. Marked functional gains in 3 patients were obtained with recovery of finger control.

Adult↗
PubMed1978

Effects of electromyographic feedback training on motor control in spastic cerebral palsy.

Electromyographic feedback training may play a special role in increasing active range of motion in spastic cerebral palsied individuals. The effects of electromyographic feedback training were documented on four persons with spastic diplegic cerebral palsy within a single subject design. Subjects received immediate auditory and visual feedback twice daily during ten consecutive days. Electromyographic feedback training resulted in increases in the active range of motion of the ankle joint of from 20 percent to 500 percent in the limbs trained during the first five days with electromyographic feedback and of from 33 percent to 450 percent in the limbs trained in the last five days. The acquired active range of motion was maintained by two of the subjects over intervals of from four to nine weeks.

Adolescent↗
PubMed1981

Clinical electromyographic feedback following meniscectomy. A multiple regression experimental analysis.

This study was designed to evaluate the relative effectiveness of electromyographic feedback and conventional physical therapy in the recovery of quadriceps femoris muscle function following uncomplicated meniscectomy. Contributions of patient characteristics and elements related to the surgery were also evaluated, using multiple regression techniques. Twenty-two men and four women were randomly assigned to two groups. One group received a traditional approach of 20 minutes of isometric exercises while the other performed 20 minutes of isometrics with electromyographic feedback. Pretreatment and posttreatment electromyographic output and strength were measured. The average difference between pretest and posttest electromyographic output for the feedback group was over 10 times higher than that of the standard therapy group. The feedback group also had significantly greater (p less than .01) changes in manual muscle test scores after each treatment. Change in maximum electromyographic output was significantly correlated with total number of days following surgery, regardless of treatment. A multiple regression analysis revealed that the greatest predictors of change in maximum electromyographic output were treatment group and days after surgery. Electromyographic feedback is demonstrated to be an efficacious and specific therapeutic modality for the patient who has had a meniscectomy.

Adult↗
PubMed1984

Perceptions of medical school faculty members and students on clinical clerkship feedback.

The authors in this study investigated faculty members' and students' perceptions of the feedback they provided or received, respectively, during the clerkships in all clinical departments at a university hospital. All faculty members who teach students in the clinical years and all third- and fourth-year medical students were surveyed. Respondents were asked to indicate, on a 7-point scale, the importance they attributed to eight feedback categories and to rate the frequency of actual feedback they felt was provided or received in these eight categories. The results indicate that while both faculty members and students perceived six of the eight feedback categories as equally important, they differed substantially in their ratings of the actual feedback provided or received.

Arizona↗
PubMed1999

Changing physicians' practices: the effect of individual feedback.

OBJECTIVE: To determine whether physicians who received feedback from six peers, six referring/referral physicians, six co-workers, and 25 patients about 55 aspects of their medical practices (e.g., able to reach doctor by phone after office hours) would make changes to their practices based on that feedback. METHOD: In an earlier study, 308 physicians were given feedback about 106 aspects of their practices in the form of mean Likert-scale ratings that (1) the peers made on 26 aspects; (2) the referring/referral physicians made on 23 aspects; (3) the co-workers made on 17 aspects; and (4) the patients made on 40 aspects. Three months later 255 of these physicians responded when asked to indicate whether they had contemplated or initiated changes, or whether no change had been necessary, regarding 31 practice aspects, each of which was a summary of one or more of 55 of the original 106 aspects on which they had received ratings. These 55 were considered the aspects most amenable to change over a short period. The physicians were also asked about the educational interventions that they felt would help them make changes. Multivariate analysis of variance was used to see whether the types of changes reported for the specific aspects of practice were associated with the feedback ratings received for those aspects. RESULTS: An examination of the responses showed that 83% of the 255 physicians reported having contemplated a change, and 66% reported having initiated a change for at least one aspect of practice. Changes were contemplated most frequently for aspects of practice associated with clinical skills and resource use. Changes were initiated most frequently for aspects of practice associated with communication with patients and support of patients. Physicians who contemplated or initiated changes had lower (i.e., more negative) mean ratings than did physicians who reported that no change was necessary, which suggests that the physicians did use their feedback ratings to decide about changes, although their qualitative comments indicated other sources as well. Printed material was chosen most often as a method of receiving continuing medical education related to making changes in the practice areas examined.

Analysis of Variance↗
PubMedDate not supplied

E.E.G. alpha feedback--a comparison of two control groups.

It is controversial whether or not veridical feedback is necessary to bring about increases in alpha activity in the feedback situation and has been suggested that the instructional variable may be a crucial determinant of outcome. In this experiment two groups of subjects were both given false feedback. One group was misled into believing that the feedback was contingent. Increases in alpha index occurred only in those subjects who believed that they were receiving contingent feedback, indicating that subjects knowledge and belief concerning the experiment were important in determining the outcome.

Acoustic Stimulation↗
PubMedDate not supplied

The self-control of the cardiovascular response to exercise using feedback of the product of interbeat interval and pulse transit time.

Feedback of the product of interbeat interval and pulse transit time (this product being a close correlate of the product of heart rate and systolic blood pressure) was compared with relaxation training and simple habituation to the experimental task. The subjects were 36 healthy volunteers tested both when inactive and when cycling on a bicycle ergometer. Subjects receiving product feedback were markedly more successful in minimizing the decrease in interbeat interval and pulse transit time caused by exercise (i.e., their rate pressure product rose less). Subjects who received relaxation training or simply exercised showed similar changes in interbeat interval and pulse transit time. In the inactive subject, the superiority of product feedback was much less evident but it did enable subjects to increase pulse transit time (i.e., decrease systolic blood pressure) compared to the other two conditions, which again did not differ. It is proposed that the superiority of product feedback may relate to its value as an index of sympathetic input to the heart and that such feedback may find clinical application in the treatment of angina pectoris.

Adolescent↗
PubMed2006

Visual-feedback therapy for antipsychotic medication adherence.

This pilot study aimed to examine the effectiveness of visual-feedback therapy for individuals with psychotic disorders. Visual-feedback therapy combines structured psychodynamic therapy and visual feedback achieved via an electronic monitoring medication cap to increase insight about medication behaviours. Thirty subjects were randomly assigned either to visual feedback or to a supportive counselling group. Medication adherence was measured by both electronic monitoring and blood plasma drug concentration levels. The results showed that, at the end of the 3-month, intervention (bimonthly sessions), adherence rates of the visual-feedback group slightly increased, but declined during the course of the study for the supportive counselling control group (P=0.026).

Adult↗
PubMed2006

Coincident scales of forest feedback on climate and conservation in a diversity hot spot.

The dynamic relationship between vegetation and climate is now widely acknowledged. Climate influences the distribution of vegetation; and through a number of feedback mechanisms vegetation affects climate. This implies that land-use changes such as deforestation will have climatic consequences. However, the spatial scales at which such feedbacks occur remain largely unknown. Here, we use a large database of precipitation and tree cover records for an area of the biodiversity-rich Atlantic forest region in south eastern Brazil to investigate the forest-rainfall feedback at a range of spatial scales from ca 10(1)-10(4) km2. We show that the strength of the feedback increases up to scales of at least 10(3) km2, with the climate at a particular locality influenced by the pattern of landcover extending over a large area. Thus, smaller forest fragments, even if well protected, may suffer degradation due to the climate responding to land-use change in the surrounding area. Atlantic forest vertebrate taxa also require large areas of forest to support viable populations. Areas of forest of ca 10(3) km2 would be large enough to support such populations at the same time as minimizing the risk of climatic feedbacks resulting from deforestation.

Animals↗
PubMed2002

Random walks with feedback on fractal lattices.

We study numerically a random walk under the competitive processes of a self-organized feedback coupling, characterized by a strength lambda and an underlying fractal lattice. Whereas a fractal structure favors a subdiffusive behavior, a dynamical feedback leads either to localization in case of an attractive feedback, lambda>0, or to superdiffusion for a repulsive memory strength lambda<0. Under the influence of both processes the dynamical exponent z is changed. For a Sierpinski gasket or a Sierpinski carpet with repulsive feedback coupling we get 2/z=1.04 or 2/z=1.08, respectively. When an attractive feedback is dominant, the system offers localization as in the case of a random walk in regular lattices. The numerical results are strongly supported by analytical studies based on scaling arguments.

Journal Article↗
PubMed1993

Feedback Regulation of Nitrate Influx in Barley Roots by Nitrate, Nitrite, and Ammonium.

The short-lived radiotracer 13N was used to study feedback regulation of nitrate influx through the inducible high-affinity transport system of barley (Hordeum vulgare L. cv Steptoe) roots. Both wild-type plants and the mutant line Az12:Az70 (genotype nar1a;nar7w), which is deficient in the NADH-specific and NAD(P)H-bispecific nitrate reductases (R.L. Warner, R.C. Huffaker [1989] Plant Physiol 91: 947-953) showed strong feedback inhibition of nitrate influx within approximately 5 d of exposure to 100 fmu]M nitrate. The result with the mutant, in which the flux of nitrogen into reduced products is greatly reduced, indicated that nitrate itself was capable of exercising feedback regulation upon its own influx. This conclusion was supported by the observation that feedback in wild-type plants occurred in both the presence and absence of L-methionine sulfoximine, an inhibitor of ammonium assimilation. Nitrite and ammonium were also found to be capable of exerting feedback inhibition upon nitrate influx, although it was not determined whether these ions themselves or subsequent metabolites were responsible for the effect. It is suggested that feed-back regulation of nitrate influx is potentially mediated through several nitrogen pools, including that of nitrate itself.

Journal Article↗
PubMed1990

Rhizobium meliloti exopolysaccharide Mutants Elicit Feedback Regulation of Nodule Formation in Alfalfa.

Nodule formation by wild-type Rhizobium meliloti is strongly suppressed in younger parts of alfalfa (Medicago sativum L.) root systems as a feedback response to development of the first nodules (G Caetano-Anollés, WD Bauer [1988] Planta 175: 546-557). Mutants of R. meliloti deficient in exopolysaccharide synthesis can induce the formation of organized nodular structures (pseudonodules) on alfalfa roots but are defective in their ability to invade and multiply within host tissues. The formation of empty pseudonodules by exo mutants was found to elicit a feedback suppression of nodule formation similar to that elicited by the wild-type bacteria. Inoculation of an exo mutant onto one side of a split-root system 24 hours before inoculation of the second side with wild-type cells suppressed wild-type nodule formation on the second side in proportion to the extent of pseudonodule formation by the exo mutants. The formation of pseudonodules is thus sufficient to elicit systemic feedback control of nodulation in the host root system: infection thread development and internal proliferation of the bacteria are not required for elicitation of feedback. Pseudonodule formation by the exo mutants was found to be strongly suppressed in split-root systems by prior inoculation on the opposite side with the wild type. Thus, feedback control elicited by the wild-type inhibits Rhizobium-induced redifferentiation of host root cells.

Journal Article↗
PubMed2004

Use of an innovative video feedback technique to enhance communication skills training.

CONTEXT: Despite growing interest in medical communication by certification bodies, significant methodological and logistic challenges are evident in experiential methods of instruction. OBJECTIVE: There were three study objectives: 1) to explore the acceptability of an innovative video feedback programme to residents and faculty; 2) to evaluate a brief teaching intervention comprising the video feedback innovation when linked to a one-hour didactic and role-play teaching session on paediatric residents' communication with a simulated patient; and 3) to explore the impact of resident gender on communication change. DESIGN: Pre/post comparison of residents' performance in videotaped interviews with simulated patients before and after the teaching intervention. Individually tailored feedback on targeted communication skills was facilitated by embedding the Roter Interaction Analysis System (RIAS) within a software platform that presents a fully coded interview with instant search and review features. SETTING/PARTICIPANTS: 28 first year residents in a large, urban, paediatric residency programme. RESULTS: Communication changes following the teaching intervention were demonstrated through significant improvements in residents' performance with simulated patients pre and post teaching and feedback. Using paired t-tests, differences include: reduced verbal dominance; increased use of open-ended questions; increased use of empathy; and increased partnership building and problem solving for therapeutic regimen adherence. Female residents demonstrated greater communication change than males. CONCLUSIONS: The RIAS embedded CD-ROM provides a flexible structure for individually tailoring feedback of targeted communication skills that is effective in facilitating communication change as part of a very brief teaching intervention.

Adult↗
PubMed2006

Temporal variation in plant-soil feedback controls succession.

Soil abiotic and biotic factors play key roles in plant community dynamics. However, little is known about how soil biota influence vegetation changes over time. Here, we show that the effects of soil organisms may depend on both the successional development of ecosystems and on the successional position of the plants involved. In model systems of plants and soils from different successional stages, we observed negative plant-soil feedback for early-successional plant species, neutral feedback for mid-successional species, and positive feedback for late-successional species. The negative feedback of early-successional plants was independent of soil origin, while late-successional plants performed best in late- and worst in early-successional soil. Increased performance of the subordinate, late-successional plants resulted in enhanced plant community diversity. Observed feedback effects were more related to soil biota than to abiotic conditions. Our results show that temporal variations in plant-soil interactions profoundly contribute to plant community assemblage and ecosystem development.

Biodiversity↗