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PubMed2002

Age-related differences and the role of augmented visual feedback in learning a bimanual coordination pattern.

The purpose of this study was to investigate the effects of aging and the role of augmented visual information in the acquisition of a new bimanual coordination pattern, namely a 90 degrees relative phase pattern. In a pilot study, younger and older adults received augmented visual feedback in the form of a real-time orthogonal display of both limb movements after every fifth trial. Younger adults acquired this task over three days of practice and retained the task well over periods of one week and one month of no practice while the older adults showed no improvement at all on the task. It was hypothesized that the amount of augmented information was not sufficient for the older adults to overcome the strong tendency to perform natural, intrinsically stable coordination patterns, which consequently prevented them from learning the task. The present study evaluated the age-related role of augmented visual feedback for learning the new pattern. Participants were randomly assigned within age groups to receive either concurrent or terminal visual feedback after every trial in acquisition. In contrast to the pilot study, all of the older adults learned the pattern, although not to the same level as the younger adults. Both younger and older adults benefitted from concurrent visual feedback, but the older adults gained more from the concurrent feedback than the younger adults, relative to terminal feedback conditions. The results suggest that when learning bimanual coordination patterns, older adults are more sensitive to the structure of the practice conditions, particularly the availability of concurrent visual information. This greater sensitivity to the learning environment may reflect a diminished capacity for inhibitory control and a decreased ability to focus attention on the salient aspects of learning the task.

Adult↗
PubMed2002

Short term and long term effects of enhanced auditory feedback on typing force, EMG, and comfort while typing.

Two studies were conducted to determine the effects of enhanced auditory feedback on typing force, electromyography (EMG) and subjective discomfort. The introduction of enhanced auditory feedback caused a 10-20% reduction in 90th percentile typing force, finger flexor EMG, and finger extensor EMG. Adaptation to the enhanced auditory feedback occurred in <3 min. After 1 week of intermittent enhanced auditory feedback there were no differences in typing force or EMG while subjects were typing with or without the enhanced auditory feedback. The continued use of auditory feedback did not further reduce the levels of typing force or EMG after 1 or 2 weeks of exposure.

Adult↗
PubMed1999

Unipedal balance in healthy adults: effect of visual environments yielding decreased lateral velocity feedback.

OBJECTIVE: To test the (null) hypotheses that the reliability of unipedal balance is unaffected by the attenuation of visual velocity feedback and that, relative to baseline performance, deterioration of balance success rates from attenuated visual velocity feedback will not differ between groups of young men and older women, and the presence (or absence) of a vertical foreground object will not affect balance success rates. DESIGN: Single blind, single case study. SETTING: University research laboratory. PARTICIPANTS: Two volunteer samples: 26 healthy young men (mean age, 20.0yrs; SD, 1.6); 23 healthy older women (mean age, 64.9 yrs; SD, 7.8). MAIN OUTCOME MEASURE: Normalized success rates in unipedal balance task. METHODS: Subjects were asked to transfer to and maintain unipedal stance for 5 seconds in a task near the limit of their balance capabilities. Subjects completed 64 trials: 54 trials of three experimental visual scenes in blocked randomized sequences of 18 trials and 10 trials in a normal visual environment. The experimental scenes included two that provided strong velocity/weak position feedback, one of which had a vertical foreground object (SVWP+) and one without (SVWP-), and one scene providing weak velocity/strong position (WVSP) feedback. Subjects' success rates in the experimental environments were normalized by the success rate in the normal environment in order to allow comparisons between subjects using a mixed model repeated measures analysis of variance. RESULTS: The normalized success rate was significantly greater in SVWP+ than in WVSP (p = .0001) and SVWP- (p = .013). Visual feedback significantly affected the normalized unipedal balance success rates (p = .001); neither the group effect nor the group X visual environment interaction was significant (p = .9362 and p = .5634, respectively). Normalized success rates did not differ significantly between the young men and older women in any visual environment. CONCLUSIONS: Near the limit of the young men's or older women's balance capability, the reliability of transfer to unipedal balance was adversely affected by visual environments offering attenuated visual velocity feedback cues and those devoid of vertical foreground objects.

Adult↗
PubMed1998

Force feedback control of motor unit recruitment in isometric muscle.

The use of simple force feedback in an isometric muscle control system utilizing orderly recruitment of motor units is explored. Cat medial gastrocnemius motor units were stimulated with and without simple force feedback gain ranging from 0.7 to 0.9. Ramp, triangular, staircase, sinusoidal and bandwidth-limited pseudo-random input recruitment signals were used to study tracking accuracy through linear correlation in ramp and triangular signals, cross correlation in sinusoidal and random signals, and rise time and steady state error in staircase signals. Dramatic improvements were found in most tested tracking variables with the use of feedback; squared correlation coefficients increased from a mean of 0.93 to 0.99 for ramp signals and from 0.76 to 0.98 in triangular signals. Mean peak cross-correlations improved from 0.85 to 0.98 in random signals and from 0.93 to 0.98 for sinusoidal inputs, and mean time to peak cross-correlations decreased from 144 to 24 ms in random signals and from 156 to 25 ms in sine waves. Rise times in staircase signals decreased from a mean of 520 to 175 ms, and mean steady state error decreased from 12 to 3%. Significant effects of the triangle cycle time, sinusoidal frequency and staircase step were found on the performance of the muscle force control system. In addition, the possible effects of intrinsic feedback mechanisms on the control system were examined by repeating the closed loop part of the study but with the sciatic nerve cut proximally. The tracking results were essentially and statistically the same as in the closed loop condition. It was concluded that a simple feedback configuration provided superior tracking performance for a practical application in which orderly recruitment is used to control muscles; furthermore, it was concluded that this type of system would be virtually immune to external disturbances such as spasticity resulting from intact spinal neural feedback mechanisms found in paralyzed individuals.

Analysis of Variance↗
PubMed2003

Improving CPR performance using an audible feedback system suitable for incorporation into an automated external defibrillator.

BACKGROUND: It has been shown that a computer-based audible feedback system can improve acquisition and retention of basic life support (BLS) skills. This system is being developed to work in association with an automated external defibrillator (AED). AIM: To determine if such a feedback system is likely to improve the quality of CPR performed by trained nurses whilst using an AED. METHOD: Thirty-six general nurses performed 3 min of BLS on a manikin connected to a laptop computer running an experimental software program. After initial testing they were randomly allocated to control or 'feedback' groups. Both groups then performed a further 3 min of BLS, but those in the feedback group received audible corrective instructions from the computer when errors of technique were detected. RESULTS: The group receiving feedback were significantly better than the control group at performing inflations (P=0.004) and achieving the correct depth of chest compression (P<0.0005). CONCLUSIONS: The results suggest that if the feedback system were to be incorporated into an AED, it could lead to better performance of CPR during a resuscitation attempt.

Adult↗
PubMed2003

Attentional blink modulation in a reaction time task: performance feedback, warning stimulus modality, and task difficulty.

The present research investigated the effect of performance feedback on the modulation of the acoustic startle reflex in a Go/NoGo reaction time task. Experiment 1 (n = 120) crossed warning stimulus modality (acoustic, visual, and tactile) with the provision of feedback in a between subject design. Provision of performance feedback increased the number of errors committed and reduced reaction time, but did not affect blink modulation significantly. Attentional blink latency and magnitude modulation was larger during acoustic than during visual and larger during visual than during tactile warning stimuli. In comparison to control blinks, latency shortening was significant in all modality conditions whereas magnitude facilitation was not significant during tactile warning stimuli. Experiment 2 (n = 80) employed visual warning stimuli only and crossed the provision of feedback with task difficulty. Feedback and difficulty affected accuracy and reaction time. Whereas blink latency shortening was not affected, blink magnitude modulation was smallest in the Easy/No Feedback and the Difficult/Feedback conditions.

Acoustic Stimulation↗
PubMed2001

Comparison of an enhanced versus a written feedback model on the management of Medicare inpatients with venous thrombosis.

BACKGROUND: A multistate randomized study conducted under the Health Care Financing Administration's (HCFA's) Health Care Quality Improvement Program (HCQIP) offered the opportunity to compare the effect of a written feedback intervention (WFI) with that of an enhanced feedback intervention (EFI) on improving the anticoagulant management of Medicare beneficiaries who present to the hospital with venous thromboembolic disease. METHODS: Twenty-nine hospitals in five states were randomly assigned to receive written hospital-specific feedback (WFI) of feedback enhanced by the participation of a trained physician, quality improvement tools, and an Anticoagulant Management of Venous Thrombosis (AMVT) project liaison (EFI). Differences in the performance of five quality indicators between baseline and remeasurement were assessed. Quality managers were interviewed to determine perceptions of project implementation. RESULTS: No significant differences in the change from baseline to remeasurement were found between the two intervention groups. Significant improvement in one indicator and significant decline in two indicators were found for one or both groups. Yet 59% of all quality managers perceived the AMVT project as being successful to very successful, and more EFI quality managers perceived success than did WFI managers (71% versus 40%). In the majority of EFI hospitals, physician liaisons played an important role in project implementation. CONCLUSION: Study results indicated that the addition of a physician liaison, quality improvement tools, and a project liaison did not provide incremental value to hospital-specific feedback for improving quality of care. Future studies with larger sample sizes, lengthier follow-up periods, and interventions that include more of the elements shown to affect practice behavior change are needed to identify an optimal feedback model for use by external quality management organizations.

Aged↗
PubMed2000

Merging information in speech recognition: feedback is never necessary.

Top-down feedback does not benefit speech recognition; on the contrary, it can hinder it. No experimental data imply that feedback loops are required for speech recognition. Feedback is accordingly unnecessary and spoken word recognition is modular. To defend this thesis, we analyse lexical involvement in phonemic decision making. TRACE (McClelland & Elman 1986), a model with feedback from the lexicon to prelexical processes, is unable to account for all the available data on phonemic decision making. The modular Race model (Cutler & Norris 1979) is likewise challenged by some recent results, however. We therefore present a new modular model of phonemic decision making, the Merge model. In Merge, information flows from prelexical processes to the lexicon without feedback. Because phonemic decisions are based on the merging of prelexical and lexical information, Merge correctly predicts lexical involvement in phonemic decisions in both words and nonwords. Computer simulations show how Merge is able to account for the data through a process of competition between lexical hypotheses. We discuss the issue of feedback in other areas of language processing and conclude that modular models are particularly well suited to the problems and constraints of speech recognition.

Cognition↗
PubMed1975

The effects of feedback on focal epileptic discharges in man. A preliminary report.

The history of the control of epileptic disturbances by conditioning techniques is reviewed. The preliminary results of a three year trial of feedback techniques in 13 epileptic patients are presented. Thirteen epileptic patients (age 2.5 leads to 39 mean, 15.1 years) with lateralized focal discharges in the EEG were given repeated trials of feedback, the focal discharges being used to trigger auditory and somatosensory stimuli. Dosages and serum levels of medication were unchanged throughout the experimental period. The number of epileptic spikes per 15 seconds was assessed by automatic trend analysis during 20 to 30 minute control, biofeedback and post-feedback epochs. On-going EEG activity was quantified by 8 channel frequency analysis over 10 second epochs. The patients made efforts to increase and decrease the number of spike discharges with and without feedback and the results of both triggered and random auditory, somatosensory, photic and combined stimulation were compared at various intervals over a period of up to three years. A marked reduction in the number of focal discharges was noted in eight (61.5%) patients during and immediately following the sessions. Intermittent biofeedback sessions were not associated with a serial reduction in the number of focal EEG discharges. There was a reduction in the number of clinical epileptic disturbances in six patients (46%) and possible reasons for this improvement are discussed. One patient suffered an increase in focal temporal lobe discharges during triggered and random auditory stimulation whereas there was a marked reduction in the number of discharges during minimal electrical stimulation of the contralateral arm. The need for careful assessment of each patient to determine appropriate feedback stimulation is stressed. One aim of this research has been to assess the feasibility of using miniature units for continuous feedback of focal discharges in epileptic patients.

Adolescent↗
PubMedDate not supplied

Cobalt ions inhibit negative feedback in the outer retina by blocking hemichannels on horizontal cells.

In goldfish, negative feedback from horizontal cells to cones shifts the activation function of the Ca2+ current of the cones to more negative potentials. This shift increases the amount of Ca2+ flowing into the cones, resulting in an increase in glutamate release. The increased glutamate release forms the basis of the feedback-mediated responses in second-order neurons, such as the surround-induced responses of bipolar cells and the spectral coding of horizontal cells. Low concentrations of Co2+ block these feedback-mediated responses in turtle retina. The mechanism by which this is accomplished is unknown. We studied the effects of Co2+ on the cone/horizontal network of goldfish retina and found that Co2+ greatly reduced the feedback-mediated responses in both cones and horizontal cells in a GABA-independent way. The reduction of the feedback-mediated responses is accompanied by a small shift of the Ca2+ current of the cones to positive potentials. We have previously shown that hemichannels on the tips of the horizontal cell dendrites are involved in the modulation of the Ca2+ current in cones. Both the absence of this Co2+-induced shift of the Ca2+ current in the absence of a hemichannel conductance and the sensitivity of Cx26 hemichannels to low concentrations of Co2+ are consistent with a role for hemichannels in negative feedback from horizontal cells to cones.

Animals↗
PubMedDate not supplied

GABA-mediated component in the feedback response of turtle retinal cones.

The negative feedback from horizontal cells to cone photoreceptors contributes to the formation of the receptive-field surround in cone photoreceptors. Recently, studies on the modulation of voltage-gated Ca(2+) currents in cone photoreceptors have led to great progress in our understanding of the mechanism of horizontal-cone feedback. Another highly probable hypothesis is that GABA mediates this feedback. This hypothesis is supported by the facts that cone photoreceptors respond to GABA and that horizontal cells release GABA. However, GABA-mediated synaptic inputs from horizontal cells to cone photoreceptors have not been demonstrated. In the present study, we examined whether cone photoreceptors receive GABAergic inputs from horizontal cells using a slice patch technique in the turtle retina. When 1 mM of GABA was applied to the cone photoreceptors, GABA-induced currents were activated. GABA-induced currents reversed their polarity at the equilibrium potential of Cl-. The application of 30 microM of SR95531, an antagonist of GABAA receptors, alone did not produce any change in the holding currents. When 200 microM of pentobarbital was introduced to potentiate the GABAergic inputs to the cone photoreceptors, however, the inhibitory action of SR95531 on GABAergic inputs became detectable. The amplitude of the GABAergic inputs, potentiated by pentobarbital, increased when the horizontal cells were depolarized by the application of 20 microM of kainate, while the amplitude decreased when the horizontal cells were hyperpolarized by the application of 10 microM of CNQX. When the cone photoreceptors were voltage clamped at a potential at which the voltage-gated Ca(2+) current was inactive, horizontal-cone feedback was not observed. However, the horizontal-cone feedback became detectable when the GABAergic inputs to the cone photoreceptors were potentiated by pentobarbital. We concluded that the contribution of GABAergic inputs from horizontal cells to cone pedicles in the formation of the receptive-field surround in cone photoreceptors is very limited but that the modulation of voltage-gated Ca(2+) currents in cone photoreceptors is a physiologically relevant mechanism for horizontal-cone feedback.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2003

Mailed feedback reduces consumption among moderate drinkers who are employed.

To test the efficacy of mailed feedback for drinking reduction among employees of a manufacturing firm, 48 drinkers were recruited and alternately assigned to receive mailed feedback on their drinking either immediately or after an 8-week waiting period. Using a delayed treatment design, participants were assessed by mail at baseline, 8, and 16 weeks. After viewing their feedback, participants indicated a higher level of importance of making a change, but not confidence in their ability. There were also significant decreases in consumption after receiving the feedback, and these changes were mediated by participants' increased perceptions regarding the "riskiness" of alcohol consumption. An additional 26 nondrinkers at baseline volunteered to participate and also were mailed feedback. Among this group, receipt of feedback indicating a very low level of risk did not lead to increased drinking. This cost-effective intervention appears to reduce consumption among light-to-moderate drinkers, and may warrant a larger place in the framework of workplace alcohol reduction programs.

Alcohol Drinking↗
PubMed2000

Rapid non-genomic feedback effects of glucocorticoids on CRF-induced ACTH secretion in rats.

PURPOSE: The present study investigates fast negative feedback actions of corticosterone (corticosteroid type I/type II receptor agonist) and RU 28362 (corticosteroid type II receptor agonist) on corticotropin-releasing factor (CRF)-induced adrenocorticotropic hormone (ACTH) secretion in rats. METHODS: To induce fast feedback, glucocorticoids were administered intravenously immediately before injection of the hypophyseotropic stimulus CRF. Plasma ACTH levels, being determined 5 to 30 min thereafter, were used as markers of fast feedback. RESULTS: Fast inhibitory effects on CRF-induced ACTH secretion became evident within 15 min (corticosterone) and 5 min (RU 28362) after steroid administration. Rapid feedback inhibition was also observed in the presence of other corticosteroids (cortisol, dexamethasone, aldosterone), whereas structurally-unrelated steroids (beta-estradiol, progesterone, potassium canrenoate, alphaxalone) were inactive in this respect. Pretreatment of rats with the corticosteroid type II receptor antagonist RU 486 or the transcription inhibitor actinomycin D left fast feedback effects unaltered. CONCLUSIONS: Our results demonstrate that glucocorticoids exert fast negative feedback at the pituitary level via a mechanism that is independent of corticosteroid type II receptor occupation and de novo synthesis of mRNA. In conclusion, corticosteroid-specific nongenomic effects may underly rapid glucocorticoid responses on CRF-induced ACTH secretion.

Adrenocorticotropic Hormone↗
PubMed1998

Feedback to minorities: evidence of a positive bias.

This research tested the prediction that Whites supply more lenient feedback to Blacks than to fellow Whites. In Study 1, White undergraduates were led to believe that they were giving feedback on essays written by either a Black or a White fellow student. As predicted, feedback was less critical when the supposed feedback recipient was Black rather than White. It was also predicted that the feedback bias would be selective for subjective evaluative domains (i.e., essay content) in contrast to objective evaluative domains (i.e., essay mechanics). An interaction between recipient race and evaluative domain confirmed this prediction. The domain-specific quality of the feedback bias suggests that the bias may arise from social motives rather than from more automatic processes. Study 2 replicated these results.

Adult↗
PubMed2006

Being controlled by normative influences: self-determination as a moderator of a normative feedback alcohol intervention.

The objectives of this research were to evaluate the efficacy of computer-delivered personalized normative feedback among heavy drinking college students and to evaluate controlled orientation as a moderator of intervention efficacy. Participants (N = 217) included primarily freshman and sophomore, heavy drinking students who were randomly assigned to receive or not to receive personalized normative feedback immediately following baseline assessment. Perceived norms, number of drinks per week, and alcohol-related problems were the main outcome measures. Controlled orientation was specified as a moderator. At 2-month follow-up, students who received normative feedback reported drinking fewer drinks per week than did students who did not receive feedback, and this reduction was mediated by changes in perceived norms. The intervention also reduced alcohol-related negative consequences among students who were higher in controlled orientation. These results provide further support for computer-delivered personalized normative feedback as an empirically supported brief intervention for heavy drinking college students, and they enhance the understanding of why and for whom normative feedback is effective.

Adult↗
PubMed2006

Comparison of meaning and graphophonemic feedback strategies for guided reading instruction of children with language delays.

PURPOSE: Guided reading is a common practice recommended for children in the early stages of literacy development. While experts agree that oral reading facilitates literacy skills, controversy exists concerning which corrective feedback strategies are most effective. The purpose of this study was to compare feedback procedures stemming from 2 different theoretical perspectives on literacy development. METHOD: Fourteen children with specific language impairment (SLI) and 21 with typically developing language read aloud 2 stories to an adult examiner who presented corrective feedback prompts when reading miscues (errors) occurred. One type of feedback based on whole language principles emphasized meaning aspects of a text. The other type consisted of graphophonemic (GP) word-decoding strategies. Before reading, participants were provided instruction on 5 key words taken from each story text. This instruction emphasized either meaning or GP aspects of specific key words. Story comprehension questions followed readings. RESULTS: Findings indicated that more miscued words were corrected overall through the use of GP feedback cues; however, some meaning-based instructional advantages were indicated for key word identifications for children with SLI. Higher story comprehension scores were yielded in the GP condition for both groups. CONCLUSIONS: Both meaning-based and phonemic key word reviews, prior to oral reading, appear to be effective strategies for children with SLI. The use of GP word-decoding cues may be more effective than meaning-based cues for facilitating correction of reading miscues during children's oral readings. Further research findings are discussed along with clinical implications for using corrective feedback procedures.

Analysis of Variance↗
PubMed1979

The effects of delayed auditory feedback and masking on the fundamental frequency of stutterers and nonstutterers.

This investigation determined if fluency of the reader or type of auditory feedback changed characteristics of fundamental frequency or duration in oral reading by stutterers or nonstutterers. Mingographic tracings were made of sentences excerpted from tape recordings of paragraphs read by 15 adult male stutterers and 15 adult male nonstutterers in three conditions of feedback: normal auditory feedback (under earphones), delayed auditory feedback (0.14 sec delay), and masking (90 dB SPL). The data included 15 measures of fundamental frequency and two measures of duration. Stutterers read sentences in greater total time and with more downward inflections than nonstutterers. Comparison of the delayed auditory feedback (DAF) conditions with the normal auditory feedback (NAF) condition showed that the numbers of total, upward, and downward inflections and upward pitch shifts increased under DAF. In the DAF condition, average rates of upward and downward inflections decreased, and mean and median fundamental frequencies and total time increased. The only changes from the NAF to the masking condition were increases in mean and median fundamental frequencies.

Adolescent↗
PubMed1980

Acoustic properties of masking/delayed feedback in the fluency of stutterers and controls.

This study examined specific acoustic variables such as auditory masking in the effect of delayed auditory feedback (DAF) on stuttered speech. Eleven stutterers and eleven controls read prose aloud under conditions of modified and masked feedback. The readers' speech was compared under conditions of synchronized and 100-msec delayed speech feedback and under four conditions of synchronized or 100-msec delayed feedback of a low frequency masker or a voice-like masker modulated by the amplitude envelope derived from the speech. Two conditions with continuous envelope masker not thus modulated were also employed. Numbers of syllables read and error frequency were scored. Control subjects were disrupted only by delayed speech feedback, but stutterers' speech was partially ameliorated by all the experimental presentations. In this respect, delayed speech feedback was not superior to the various speech-contingent masking conditions. Modulated masking was more effective than continuous masking, irrespective of delay. The ameliorative effects of DAF therefore appear nonspecific, and models for stuttering based on neural delay loops and the concept of perceptual interference are considered premature.

Adolescent↗