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PubMed1986

Visual dominance in the cross-modal kinesthetic to kinesthetic plus visual feedback condition.

In previous studies subjects who have learned a positioning response with kinesthetic feedback tended to make greater errors when visual feedback was provided during later trials. These subjects have always performed with both kinesthetic and visual feedback available. This study determined whether subjects with only visual feedback would produce errors similar to those who received kinesthetic plus visual feedback. Blindfolded subjects learned to move a handle to a criterion location with knowledge of results following each trial. Subjects then were assigned to one of three experimental groups, with only kinesthetic feedback, with kinesthetic plus visual feedback, or with only visual feedback. Subjects had 9 trials without knowledge of results in these feedback conditions. When visual feedback was available, subjects tended to make longer response errors. This finding replicates previous studies. Also, the similarity of performances from the conditions with visual feedback indicated the dominance of visual information in the condition with kinesthetic plus visual feedback.

Feedback↗

PubMed1997

Effectiveness of visual feedback during isokinetic exercise.

Although previous investigators have observed that knowledge of performance via visual feedback tends to enhance performance during an isokinetic test, the time frame over which visual feedback remains advantageous is unclear. The purpose of this study was to compare knee extensor torques produced by visual feedback and no visual feedback groups on three occasions, completed over a 2-week period, and at 4 weeks after the third test. Healthy, sedentary subjects were each randomly assigned to either a visual feedback or a no visual feedback group (N = 10 males and 10 females per group). Visual feedback consisted of viewing a computer monitor which displayed the current and a target knee extension force. Torques produced by the visual feedback group were consistently greater (p < 0.05) and more reliable than those produced by the no visual feedback group. The effectiveness of visual feedback tended to decrease over the first three occasions, suggesting that visual feedback may not be as advantageous once a skill is well learned. Further research needs to examine the contribution of visual feedback to motor learning as well as retention and transfer of motor skills during more complex functional tasks.

Adult↗

PubMed1995

Pure feedback effects in absolute identification.

To reveal the pure effects of trial-by-trial feedback on judgmental accuracy and sequential dependencies independent of global anchoring effects and other influences, we presented subjects with sequences consisting alternately (within an experimental session) of short runs of trials with feedback (feedback sequences) and without feedback (no-feedback sequences). In Experiments 1 and 2 (absolute identification of sound intensity and sound frequency, respectively), judgmental accuracy was the same in the feedback and the no-feedback sequences, contrary to previous results. Also, in the feedback sequences, the dependency of the current response on the immediately preceding stimulus was larger than that in the no-feedback sequences, while the dependency on the previous response was larger in the no-feedback sequences. In Experiment 3 (absolute identification of sound frequency), we attempted to separate the effects of the number of response categories on sequential dependencies from the effects of the number of stimuli. The results showed that the number of response categories had a larger effect than the number of stimuli on most aspects of performance, but that both affected sequential dependencies. These results are generally consistent with a theory of absolute identification in which feedback affects judgmental accuracy by improving long-term memory for judgmental anchors, while feedback affects sequential dependencies by altering response biases.

Auditory Perception↗

PubMed2004

Word learning can be achieved without feedback: implications for aphasia therapy.

PURPOSE: Children acquire new words through exposure, without the necessity for explicit feedback by caregivers. In aphasia therapy, feedback to the patient is considered an important asset even though the empirical base demonstrating superior learning with online feedback is lacking. The present study examined if healthy adults and patients with chronic aphasia can acquire a new lexicon by intense frequency of exposure alone. METHODS: We compared learning rates with "frequency of exposure alone" (no-feedback condition: n=19 healthy adults; two patients with chronic Broca's and Wernicke's aphasia, respectively) with a condition where subjects additionally received online feedback (feedback condition; n=19). The learning principle was higher statistical co-occurrences of "correct" picture-pseudoword pairings as compared to "incorrect" pairings. In the feedback condition, immediate online feedback on the correctness of respective choices was additionally provided. RESULTS: Both healthy groups successfully acquired the vocabulary. Feedback led to a slight initial acceleration of learning but did not improve latency to peak performance or long-term retention of lexical knowledge. These findings show that high frequency interactive exposure is a potent word learning mechanism in adults and that feedback is not crucial. This is further corroborated by our successful training of two patients with chronic aphasia without online feedback. CONCLUSIONS: Our findings demonstrate that word re-learning in aphasia could benefit from maximizing on the frequency of exposure and exploiting the therapeutic principle of "massed practice", which has been successful in physical rehabilitation after stroke. Additionally, economizing on feedback may prevent patients becoming discouraged by continuous confrontation with their deficits.

Adult↗

PubMed2004

Data feedback efforts in quality improvement: lessons learned from US hospitals.

BACKGROUND: Data feedback is a fundamental component of quality improvement efforts, but previous studies provide mixed results on its effectiveness. This study illustrates the diversity of hospital based efforts at data feedback and highlights successful strategies and common pitfalls in designing and implementing data feedback to support performance improvement. METHODS: Open ended interviews with 45 clinical and administrative staff in eight US hospitals in 2000 concerning their perceptions about the effectiveness of data feedback in supporting performance improvement efforts were analysed. The hospitals were chosen to represent a range of sizes, geographical regions, and beta blocker improvement rates over a 3 year period. Data were organized and analyzed in NUD-IST 4 using the constant comparative method of qualitative data analysis. RESULTS: Although the data feedback efforts at the hospitals were diverse, the interviews suggested that seven key themes may be important: (1) data must be perceived by physicians as valid to motivate change; (2) it takes time to develop the credibility of data within a hospital; (3) the source and timeliness of data are critical to perceived validity; (4) benchmarking improves the meaningfulness of data feedback; (5) physician leaders can enhance the effectiveness of data feedback; (6) data feedback that profiles an individual physician's practices can be effective but may be perceived as punitive; (7) data feedback must persist to sustain improved performance. Embedded in several themes was the view that the effectiveness of data feedback depends not only on the quality and timeliness of the data, but also on the organizational context in which such efforts are implemented. CONCLUSIONS: Data feedback is a complex and textured concept. Data feedback strategies that might be most effective are suggested, as well as potential pitfalls in using data to promote performance improvement.

Adrenergic beta-Antagonists↗

PubMed2005

The balance control of bilateral peripheral vestibular loss subjects and its improvement with auditory prosthetic feedback.

OBJECTIVES: We investigated whether long-term bilateral vestibular loss subjects could combine auditory biofeedback of trunk sway with their remaining natural sensory inputs on balance to provide an improved control of trunk sway. A successful integration of natural and artificial signals would provide a basis for a balance prosthesis. METHODS: Trunk sway of 6 bilateral peripheral vestibular loss subjects (BVL) was recorded using either angular position- or velocity-based auditory feedback or no feedback during stance and gait tasks. Roll and pitch trunk movements were recorded with angular velocity transducers mounted just above the waist and feedback without a delay to 4 loudspeakers placed at the left, right, front and rear borders of the 5 m long by 4 m wide test environment. The two types of auditory feedback or no feedback were provided to the subjects in random order. In the feedback modes, sway greater than a preset angle (ca. 0.5 deg) or velocity (ca. 3 deg/s) thresholds caused a tone to be emitted from the speaker towards which the subject moved. The tone volume increased with increasing angle or angular velocity amplitude. RESULTS: For all stance tasks BVL subjects without auditory feedback had a significantly different balance control with respect to that of normal controls. BVL sway values eyes open on a normal surface were reduced with auditory feedback with the greatest reductions in the roll plane. Specifically for the task of standing on 1 leg eyes open with position-auditory- feedback, amplitudes of pitch and roll angles and angular velocities were indistinguishable from those of normal controls. Sway during stance tasks on foam with eyes closed showed no improvement with feedback, remaining greater than normal. For some gait tasks there was a decrease in trunk sway with velocity feedback. CONCLUSION: These initial results indicate that subjects with vestibular loss could incorporate the auditory prosthetic sensory information into their balance commands, particularly in the roll plane if the balance task is performed with eyes open. Position information appears more useful than velocity information in reducing trunk sway during stance tasks. Future work will need to determine the effect of a training time on the improvement in balance control using such a prosthetic device and the ideal position and velocity auditory feedback combination.

Adult↗

PubMed2004

Visual feedback reduces bimanual coupling of movement amplitudes, but not of directions.

To what extent does visual feedback shape the coordination between our arms? As a first step towards answering this question, this study compares bimanual coupling in simultaneous bimanual reversal movements that control cursor movements on a vertical screen. While both cursors were visible in the control condition, visual feedback was prevented in the experimental condition by deleting one or both cursors from the screen. Absence of visual feedback for one or both arms significantly increased the reaction times of both arms and the movement amplitude of the occluded arm. Temporal coupling between the arms remained unchanged in all feedback conditions. The same was true for spatial coupling of movement directions. Amplitude coupling, however, was significantly affected by visual feedback. When no feedback for either arm was available, amplitude correlations were significantly higher than when feedback for one or both arms was present. This finding suggests that online visual feedback decreases bimanual amplitude coupling, presumably through independent movement corrections for the two arms. The difference between movement amplitudes and movement directions in their susceptibility to visual feedback supports the idea that they are subserved by different control mechanisms. Analysis of eye movements during task performance revealed no major differences between the different feedback conditions. The eye movements of all subjects followed a stereotypical pattern, with generally only one saccade after target onset, directed towards the average position of all possible targets, irrespective of feedback condition and target direction.

Adult↗

PubMed2005

The involvement of glutamate-gated channels in negative feedback from horizontal cells to cones.

Photoreceptors are the light sensitive cells in the retina. They project to horizontal cells and bipolar cells via a glutamatergic feed forward pathway. Horizontal cells are strongly electrically coupled and integrate in that way the input from the photoreceptors. Horizontal cells feedback to cones negatively. The combined signal from the photoreceptors and the horizontal cells is sent to the bipolar cells. The feedback pathway from horizontal cells to cones is thought to form the basis for the center/surround organization of bipolar cells. The nature of the feedback pathway is an issue of intense debate. It was thought for a long time that this feedback pathway was GABAergic, because cones have GABA-receptors and horizontal cells release GABA via a GABA-transporter working in the reversed direction. However, recently we showed in goldfish that horizontal cells feed back to cones via an alternative mechanism. In goldfish, negative feedback from horizontal cells to cones shifts the calcium current of the cone to more negative potentials. This feedback pathway is independent of GABA, since feedback cannot be blocked by either saturating concentrations of PTX, the GABA-transporter blocker SKF89976A, or application of GABA. The mechanism of negative feedback from horizontal cells to cones involves hemichannels located at the tips of the invaginating horizontal cells, just opposite to the calcium channels of the cones. Current flowing through these hemichannels changes the extracellular potential deep in the synaptic cleft and in that way modulates the calcium current of the cones. Such a modulation of the extracellular potential is called ephaptic. If negative feedback from horizontal cells to cones is indeed ephaptic, other channels present in the synapse should also be able to act as a current source, i.e., should also be able to change the output of the cone. We showed that glutamate-gated channels present at the tips of the horizontal cell dendrites can also mediate feedback responses. Surprisingly, although the glutamate-gated conductance of the horizontal cells is eight times the hemichannel conductance, glutamate-gated channels are not the major current source in negative feedback from horizontal cells to cones. In this chapter we present evidence that this is due to the more focal localization of the hemichannels, compared to a diffuse and extrasynaptic localization of the glutamate-gated channels.

Animals↗

PubMed2005

Force feedback plays a significant role in minimally invasive surgery: results and analysis.

OBJECTIVE: To evaluate the role of force feedback with applications to minimally invasive surgery (MIS). Two research hypotheses were tested using our automated laparoscopic grasper. SUMMARY BACKGROUND DATA: Conventional laparoscopic tools do not have the ability of providing force feedback to a surgeon when in use with or without robotic surgical systems. Loss of haptic (force and tactile) feedback in MIS procedures is a disadvantage to surgeons since they are conventionally used to palpating tissues to diagnose tissues as normal or abnormal. Therefore, the need exists to incorporate force feedback into laparoscopic tools. METHODS: We have developed an automated laparoscopic grasper with force feedback capability to help surgeons differentiate tissue stiffness through a haptic interface device. We tested our system with 20 human subjects (10 surgeons and 10 nonsurgeons) using our grasper to evaluate the role of force feedback to characterize tissues and answer 2 research hypotheses. RESULTS: Our experiments confirmed 1 of our 2 research hypotheses, namely, providing both vision and force feedback leads to better tissue characterization than only vision feedback or only force feedback. CONCLUSIONS: We have validated 1 of our 2 research hypotheses regarding incorporating force feedback with vision feedback to characterize tissues of varying stiffness.

Biocompatible Materials↗

PubMed1980

Characteristics and ionic processes involved in feedback spikes of turtle cones.

In about 20% of the cones of untreated retinas of turtles, bright flash illumination of the periphery of their receptive field evokes a spike through the feedback mechanism from the L-horizontal cell. Such feedback spikes, never observed with central stimulation, are labile, but after they have disappeared they can be regained by depolarizing the cone. Feedback spikes are actual regenerative responses, since they show a critical threshold potential, are facilitated by cone depolarization and are blocked by hyperpolarization. They are associated with a membrane resistance decrease; tetrodotoxin (10(-5) M) does not block them. High Ca2+ media facilitate their appearance, but their effect is transient because of the cone hyperpolarization and the light response block that Ca2+ ions induce. Sr2+ ions (4-10 mM) facilitate the discharge of feedback spikes in response to peripheral illumination in every cone, whether or not it has previously shown feedback effects. In Sr2+ media, feedback spikes are stable and can be evoked by dim lights. Ba2+ (2-6 mM) also facilitates and stabilizes the discharge of feedback spikes. Co2+ and D-600 block the feedback spikes. Pharmacological agents that depolarize the L-horizontal cells, such as GABA, glutamate or nicotine, also block the feedback spikes. Both Sr2+ and Ba2+ also induce the appearance of spontaneous and off spikes, which are also blocked by Co2+, but these are not related to the feedback mechanism. These results strongly suggest that every turtle cone receives a feedback input from the L-horizontal cells, which would be able to induce an increase of the cone Ca2+ conductance, which may become regenerative.

Action Potentials↗

PubMed2006

The effects of different forms of feedback on fuzzy and verbatim memory of science principles.

BACKGROUND: Previous models of the effects of feedback account for lower-order learning outcomes but do not adequately describe experimental findings for higher-order learning. AIMS: Based on a connectionist model of feedback effects, this investigation aims to show that feedback that allows only one learner response facilitates proposition-specific verbatim encoding, while feedback that requires the learner to try again on error facilitates relational fuzzy encoding. Sample and methods. Volunteer high school students were randomly assigned to one of 5 print-based lesson treatments that consisted of four science expository texts with adjunct inference-level questions covering science principles. The five treatments included delayed feedback, single-try immediate feedback, multiple-try immediate feedback, and two control treatments, questions without feedback, and text only. A post-test given 5 days after instruction was designed to measure both verbatim and fuzzy outcomes. RESULTS: Multiple-try immediate feedback was best for paraphrased post-test questions (fuzzy) and worse for verbatim post-test questions. CONCLUSIONS: Fuzzy trace theory complements a connectionist model of feedback, and may provide a fruitful approach for describing the effects of feedback on different learning outcomes.

Adolescent↗

PubMed2005

Effect of tactile feedback on movement speed and precision during work-related tasks using a computer mouse.

Effects of tactile feedback on movement accuracy and speed were studied. Younger and older participants performed three tasks (1, select and drag word; 2, menu navigation; 3, select and drag cell) using commercial software and a mouse with or without tactile feedback. Task time and error number were recorded. Tasks were divided according to presence or absence of tactile feedback, and participants were divided into subgroups (high, average, low) based on Task 1 performance. Overall, older participants took longer (p < .0001) and made more errors (p < .001) than younger participants. There was an effect of feedback by task in younger participants for all six outcomes (p < 0.02). At the task level, with feedback, younger participants reduced performance time (13%) and errors (24%) on Task 1. Low- and average-performance younger participants benefited most from feedback for Task 1. Older low-performance participants also benefited from feedback for Task 1. For Task 3, older participants tended to take more time and make more errors with feedback. Tactile feedback may enhance performance when feedback is event related. Older people may not integrate sensation as well as younger individuals to enhance performance. Potential applications of this research include the development of tactile feedback interfaces to facilitate computer use.

Adult↗

PubMed2005

[Educative effect of feedback after medical interview in objective structured clinical examination].

OBJECTIVE: Objective Structured Clinical Examination (OSCE) is widely used to assess the core competency of dental residents. However, the educative effect of feedback in OSCE has not been fully examined. Therefore, we investigated the educative effect of formative feedback in a medical interview station. METHODS: The subjects were 51 residents in the clinical training course of our dental hospital. After completing the medical interview station, residents were individually given formative feedback by evaluators and standardized patients. Two months later, residents were asked to fill in a questionnaire about the contents of feedback and self-rating mental strain level during OSCE. Videotaped performance and feedback were reviewed by investigators to check the answers to the questionnaire. RESULTS: Evaluators provided an average of 3.1 feedback items, and standardized patients provided an average of 1.6 feedback items for each resident. However, each resident remembered an average of 1.3 feedback items from evaluators and 0.9 from standardized patients. The lower the score of residents in the medical interview station, the more feedback items were given to residents. A significant negative correlation was found between the score of evaluators and self-rating mental strain level (Spearman rho = -0.326, p = 0.019). CONCLUSION: For effective feedback, evaluators or standardized patients should focus on 2 to 3 items of essential points in OSCE. Repetition of feedback using videotaped performance may be useful to improve communication skills for medical interview.

Education, Dental↗

PubMed2001

A comparison between different formats of educational feedback to junior doctors: a prospective pilot intervention study.

OBJECTIVES: Audit feedback is conventionally given in the format of an average performance of the department relative to established guidelines. The impersonality of this feedback format may compromise audit outcome. The aim of the study was to compare personal, peer-comparison feedback, an effective method of changing physician practice, to the 'conventional' departmental one. METHODS: Eleven SHOs working at a central London A&E department were audited in terms of the adequacy of their documentation process. The study comprised patients presenting with closed head injury, acute asthma and chest pain of possible cardiac origin. Personal peer-comparison feedback and average departmental feedback was given for the first two groups, respectively. No feedback was given for the chest pain group, acting as a temporal control. The outcome measure was documentation of the minimum variables, as specified by departmental guidelines. RESULTS: The peer-comparison feedback group showed a significant improvement (p-value<0.0001) in two out of three target variables audited, in contrast to the departmental feedback group and the control group which did not show a significant improvement in any of the variables. CONCLUSIONS: Personal, confidential peer-comparison feedback was more effective than departmental feedback, in an audit of process of junior doctors. This pilot study should form the basis of a larger study (more SHOs, wider range of conditions) to establish unequivocally the best format for educational feedback.

Education, Medical, Continuing↗

PubMed1982

Feedback effects on target search and velocity extrapolation by mentally retarded and nonretarded adolescents.

Equal-CA EMR and nonretarded adolescents stylus-tracked an intermittently disappearing rotary pursuit target with no feedback, auditory feedback, and visual feedback. With no feedback both groups demonstrated an approximately equal increase in distance errors during an 18-second period following disappearance of the target. With auditory and visual feedback, the nonretarded group remained closer to the target than with no feedback and closer than the retarded group under all three feedback conditions. Retarded subjects made more distance errors on a static search task requiring the use of auditory or visual feedback to locate a stationary target. Matching subsets of subjects from both groups on the basis of performance during the static search task eliminated differences in tracking performance during feedback. The ability to use feedback during static search predicted the ability to use feedback during rotary pursuit tracking.

Adolescent↗

PubMed1976

On the self-regulation of the occipital alpha rhythm: control strategies, states of consciousness, and the role of physiological feedback.

In an experiment investigating the self-control of occipital alpha strength, a factorial design was employed with two levels of feedback (available or non-available), three levels of instruction (Cognitive, Oculomotor, and none), and two levels of lighting (on and off), except that the no-feedback-no-instruction group was not run. The Cognitive instructions were based on the strategies reported in the literature: To generate alpha, persons were instructed to relax, "let go", try to feel pleasant and serene, and allow themselves to review pleasant personal experiences; to suppress alpha, persons were instructed to concentrate, try hard, exert themselves mentally, and try to fell anxious or frustrated. The Oculomotor instructions to generate alpha were to visually blur and not focus, and to suppress alpha were to "look" and focus. The results led to the following conclusions: (a) Feedback-augmented enhancement and suppression of occipital alpha strength is always mediated by learned control of oculomotor processes, although sometimes persons are not aware that they are employing this strategy, especially in the case of alpha enhancement; alpha feedback trainees learn to "not look" in order to enhance alpha strength. (b) Whenever Cognitive strategies are successful in producing alpha strength changes, this is due to the fact that they can be efficient mediators of changes in oculomotor processes. (c) Feedback together with simple Oculomotor instructions leads to more successful alpha control than either alone. (d) High or enhanced levels of occipital alpha strength are not invariably accompanied by the "alpha experience", in fact, if a person is not led to expect it, the alpha experience will usually not occur during occipital alpha enhancement feedback. (e) States of nonsensory awareness, such as an absorption in thoughts and feelings, are reliably associated with enhanced occipital alpha strength. This association is what would be expected: Since vision is the dominant sensory modality in humans, it is reasonable that when visual processing is reduced during alpha enhancement feedback that there is also reduced sensory awareness in general and often greater attention to thoughts and feelings. (f) Alpha feedback per se is neither necessary for nor especially facilitative of the achievement of the alpha experience. Thus, if the alpha experience is more likely to occur with alpha feedback than without it, this is due to the special circumstances that make up the feedback situation and not due to alpha feedback per se.

Alpha Rhythm↗

PubMed1985

Sensory feedback in the learning of a novel motor task.

The role of different forms of feedback is examined in learning a novel motor task. Five groups of ten subjects had to learn the voluntary control of the abduction of the big toe, each under a different feedback condition (proprioceptive feedback, visual feedback, EMG feedback, tactile feedback, force feedback). The task was selected for two reasons. First, in most motor learning studies subjects have to perform simple movements which present hardly any learning problem. Second, studying the learning of a new movement an provide useful information for neuromuscular reeducation, where patients often also have to learn movements for which no control strategy exists. The results show that artificial sensory feedback (EMG feedback, force feedback) is more powerful than "natural" (proprioceptive, visual, and tactile) feedback. The implications of these results for neuromuscular reeducation are discussed.

Journal Article↗

PubMed1991

Event-related potentials to different feedback stimuli.

Event-related potentials (ERPs) were recorded in a time estimation task under different feedback conditions, in which the informative value of the feedback signals (true versus false) was manipulated. A control condition was added in which no signal was presented. Fifteen subjects pressed a button 3 seconds after presentation of a warning signal. Two seconds after the response, a visual feedback signal was presented, indicating whether the preceding interval was estimated correctly. Two different slow waves were observed: the response was preceded by a readiness potential and the feedback stimulus was preceded by a negative slow wave called the stimulus-preceding negativity. The readiness potential was not influenced by the different feedback conditions. The stimulus-preceding negativity was larger in the true feedback condition compared to the false feedback and no feedback conditions. The P300 to the feedback signal was also larger following a true as compared to a false feedback signal. The conclusion is that the stimulus-preceding negativity is an anticipatory component contingent upon the presentation of an informative feedback signal.

Adult↗