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PubMed2003

A phoneme-grapheme feedback consistency effect.

Recent studies examining the feedback consistency effect have been criticized for poor item selection (Peereman, Content, & Bonin, 1998). In the present study, an experiment was run with a new set of items, in which feedback consistency was manipulated at a phoneme-grapheme level. The results suggested that participants responded faster to feedback-consistent words than to feedback-inconsistent words. This was despite the feedback-consistent and feedback-inconsistent word groups' being matched on many other dimensions, including word frequency and subjective orthographic frequency. These results may differ from those of previous studies, since previous studies in English have measured feedback consistency at the rime-body level.

Choice Behavior↗
PubMed1988

[The effect of social feedback on receiver's self-concept change: an examination of the role of receiver's perception on sender's self-concept].

Cognitive processes for feedback information on self-concept as influenced by the receiver's perception of the sender's trait were examined in 40 male and female undergraduates. Subjects in the consistent and inconsistent feedback situations received information consistent and inconsistent with their initial self-rating of a trait, respectively. The sender (confederate) had a higher or lower scale score for the same trait than the subjects. Subsequently, subjects did final self-rating. Inconsistent feedback produced self-concept changes no more than consistent feedback only when the sender had a higher trait tendency than the subjects. This finding suggests: (1) only in the inconsistent feedback situation, the receiver sets out to search cause of feedback; (2) whether or not the receiver changes one's self-concept depends on causal attribution of inconsistent feedback; and (3) the direction of causal attribution is influenced by the receiver's consideration of the sender's trait tendency.

Adult↗
PubMed1999

Glucocorticoid fast feedback is not altered in rats prenatally exposed to ethanol.

Animals exposed in utero to ethanol exhibit hormonal hyperresponsiveness to stressors in adulthood. One possible mechanism for this hyperresponsiveness is a deficit in negative feedback regulation of the hypothalamic-pituitary-adrenal axis. The present study tested the hypothesis that a deficit in the fast feedback time domain may play a role in the hormonal hyperresponsiveness in ethanol-exposed rats. Sprague-Dawley offspring from prenatal ethanol (E), pair-fed (PF), and ad lib-fed control (C) groups were tested in two experiments. Experiment 1 used a swim stress paradigm and tested animals at the trough of the corticosterone (CORT) circadian rhythm. Experiment 2 used ether stress and tested animals at the peak of the circadian rhythm. Animals were injected subcutaneously with CORT or saline and were immediately subjected to either a 5-min swim stress or a 1-min ether stress. Half the animals were terminated immediately after stress (5-min postinjection), and the rest were terminated 25 min later. Plasma levels of CORT and ACTH were assayed to determine whether E animals differed from control animals in showing a CORT-induced blunting of the ACTH response to the stressor, indicating alterations in fast feedback regulation. Injection of CORT significantly blunted the ACTH response to swim stress (experiment 1) in E, PF, and C females and males, compared with their saline-injected counterparts. There were no significant differences among groups. Similarly, CORT-injected males in E, PF, and C groups all exhibited a significantly blunted ACTH response to ether stress (experiment 2). CORT-injected C females also exhibited a significantly blunted ACTH response to ether stress, whereas E females showed an obvious CORT decrease that approached significance. However, PF females showed a clear deficit in fast feedback regulation. Together, these data suggest that: (1) CORT injection can serve as a fast feedback signal that can blunt the ACTH response to a stressor; and (2) prenatal ethanol exposure does not produce a deficit in hypothalamic-pituitary-adrenal feedback regulation in the fast feedback time domain.

Adrenal Cortex Hormones↗
PubMed1999

Defining the role of haptic feedback in minimally invasive surgery.

INTRODUCTION: The applications of Minimally Invasive Surgery (MIS) and Laparoscopy are rapidly expanding. Despite this expansion, the technology related to our understanding of the importance of haptic feedback related to laparoscopic surgery remains in its infancy. While many surgeons feel that the use of minimally invasive techniques eliminates force feedback and tactile sensation, the importance of haptics in MIS has not been fully evaluated. Moreover, there is considerable interest in the development of haptic simulators for MIS even though the importance of force feedback remains poorly understood. This study was designed to determine the ability of novice surgeons to interpret haptic feedback with respect to texture, shape and consistency of an object. METHOD: Subjects were presented objects in a random order and participants were blinded as to their identity. Inspection by direct palpation, palpation with conventional instruments, and palpation with laparoscopic instruments was performed on all objects. Statistical analysis of the data was performed using a Fischer exact probability test. RESULTS: Direct palpation provided the greatest degree of haptic feedback and was associated with the highest accuracy for texture discrimination, shape discrimination, and consistency discrimination. A significant decrease in the ability to identify shapes was noted with both CI and LI. A significant decrease in the ability to differentiate consistency was noted for LI only. When comparing palpation with conventional instruments to palpation with laparoscopic instruments, there was no significant difference in shape or texture discrimination. There was, however, a significant decrease in consistency discrimination. CONCLUSION: This data indicates that laparoscopic instruments do in fact provide the surgeon with haptic feedback. While the instruments change the information available to the surgeon, interpretation of the texture, shape and consistency of objects can be performed. Our ongoing work is directed at further defining force interactions. Through the use of force feedback impulse devices in VR simulators, one should be able to create a more realistic theatre in which the novice surgeon can learn operative skills that will readily translate into the operating room.

Feedback↗
PubMed1992

Need for and influence of feedback from the Finnish birth register to data providers.

Data for the Finnish medical birth register (established 1987) are collected by local hospital personnel as a part of their routine work. The purpose of this study was to study the need of personnel for feedback and the impact of feedback on later data quality. Furthermore, we studied whether such feedback tends to modify extreme cesarean section rates. Data on attitudes towards the birth register and on the need for feedback of data providers were collected through interviews and observations. In March 1988, an information package describing births, birth procedures and infant outcomes in each hospital compared with other hospitals was sent to a random stratified sample of 26 hospitals out of a total of 53. Opinions of the package were obtained by questionnaire from 104 physicians and nurses (82% response rate). Most hospital personnel, especially physicians, had negative attitudes towards the birth register. Comparison of the hospitals which had received feedback with other hospitals in terms of quality of data furnished in 1987 and 1988 suggested that feedback may improve the technical quality of data. There was no evidence, however, that feedback caused hospitals to change their practices in regard to cesarean sections.

Attitude of Health Personnel↗
PubMed2002

Objective surgical performance evaluation based on haptic feedback.

In order to develop effective virtual reality training systems for surgery there is a need to provide appropriate sensory and performance feedback to the user. This paper aims to demonstrate a method by which performance data can be collected. This is used to investigate the effect of haptic feedback on performance. A PHANTOM desktop device was used in conjunction with a suturing simulation A pair of needle-holders was instrumented with strain gauges and attached to the stylus of the PHANTOM allowing the measurement of force application and time. Suturing performance was evaluated in terms of stitch completion time, peak force application, and the length and straightness of the stitch. The effect of the level of force feedback provided by the simulation and performance over time was considered. The results indicate that the presence of force feedback affected task completion time, peak force application and the straightness of the stitch. Task completion time was shown to increase with the level of force feedback provided. Performance was seen to improve over time in terms of task completion time and the accuracy ofthe stitch. The work has examined how the presence and level of force feedback affects performance of a simple task. The accuracy of haptic feedback is important in the design of surgical simulation systems to ensure effective training transfer. A data collection method by which objective performance evaluation can be made is demonstrated. The method can be applied to training using bench models, simulations and potentially in the operating theatre.

Clinical Competence↗
PubMed2004

Giving feedback to learners in the practice.

BACKGROUND: Many general practitioners accept vocational registrars and medical students into their practice. Giving feedback to students on their work performance is an essential component of teaching in general OBJECTIVE: This article examines the central role of feedback in the teaching of medical students and registrars and provides practical guidelines on how to provide feedback in the setting of a busy general practice, describes some barriers and pitfalls, and provides a registrar's perspective on what learners see as important. DISCUSSION: For feedback to be effective, it must be given in a supportive environment. Feedback that is specific to the learner performance is highly valued by learners, whereas nonspecific evaluative feedback is less valued. The mentoring relationship between teacher and learner is crucial to giving effective feedback. Learners appreciate a teacher's help identifying any area for improvement, then being given the chance to work out the answers for themselves instead of being told exactly what to do by the more experienced teacher.

Education, Medical↗
PubMed1993

Behavioral assessment of adaptive feedback equalization in a digital hearing aid.

An evaluation was made of the efficacy of a digital feedback equalization algorithm employed by the Central Institute for the Deaf Wearable Adaptive Digital Hearing Aid. Three questions were addressed: 1) Does acoustic feedback limit gain adjustments made by hearing aid users? 2) Does feedback equalization permit users with hearing-impairment to select more gain without feedback? and, 3) If more gain is used when feedback equalization is active, does word identification performance improve? Nine subjects with hearing impairment participated in the study. Results suggest that listeners with hearing impairment are indeed limited by acoustic feedback when listening to soft speech (55 dB A) in quiet. The average listener used an additional 4 dB gain when feedback equalization was active. This additional gain resulted in an average 10 rationalized arcsine units (RAU) improvement in word identification score.

Adaptation, Physiological↗
PubMed1996

Mortyn Jones Memorial Lecture--1995. Calcium checks cyclic AMP--corticosteroid feedback in adenohypophysial corticotrophs.

This paper summarizes a particular aspect of the stress response-the negative feedback control of anterior pituitary adrenocorticotrophin secretion with special focus on the mechanism of action of protein(s) rapidly induced by glucocorticoids. The main thesis is that the principal intracellular mechanism underlying corticosteroid inhibition of corticotroph secretory function is the opposition of cAMP-mediated activation by calcium ions. An increase of intracellular cAMP levels in corticotrophs produces a rise in intracellular free Ca2+ known to be essential for triggering hormone secretion. In parallel, calcium regulates agonist-induced cAMP accumulation through inhibition of adenylyl cyclase and the stimulation of cAMP-degrading phosphodiesterase. Furthermore, a key action of cAMP is the inhibition of a slow, sustained potassium current which is activated by calcium ions. Collectively, the actions of calcium constitute a powerful intracellular feedback inhibition of cAMP-induced cellular activation. Analysis of corticosteroid action in mouse corticotroph tumour (AtT20) cells indicates that the essence of corticosteroid feedback inhibition is the amplification of intracellular calcium feedback. A common mediator of the inhibitory actions of calcium may be the calcium receptor protein calmodulin the de novo synthesis of which is rapidly stimulated by glucocorticoid hormones. Targets of glucocorticoid-induced calmodulin may include the protein phosphatase calcineurin, calmodulin-activated phosphodiesterase(s), and BK-type potassium channels. The net result of calcium feedback inhibition is a reduction of Ca2+ available for the facilitation of secretory activity i.e. calcium-induced desensitization. It is proposed that the intracellular calcium feedback loop outlined above also operates in the CNS components of negative corticosteroid feedback. A personal note: Professor Mortyn Jones introduced me to this field of research. His open-minded and critical approach to experimental work has always remained a guiding principle for my own efforts, and I hope that this paper which is dedicated to his memory will be found worthy of its purpose.

Adrenocorticotropic Hormone↗
PubMed1996

Hypercortisolemia, hippocampal glucocorticoid receptors, and fast feedback.

Glucocorticoids are critical for survival. The absence of glucocorticoids leads to the inability of the organism to cope with stress and subsequent death. However, diseases of glucocorticoid excess, such as Cushing's disease, make it clear that 'too much circulating glucocorticoids is also bad.' The need to control the circulating levels of glucocorticoids to prevent oversecretion leads to an elaborate set of checks and balances, in particular, the levels of glucocorticoid 'feedback' to the controlling elements to turn off glucocorticoid secretion and consequently maintain the homeostatic range of glucocorticoids. In order to accomplish these goals, multiple types of feedback exist which appear to use different intracellular mechanisms. In addition to multiple types of feedback, there are multiple sites of feedback including numerous limbic areas that influence the inhibition of the stress response. In this article, we will discuss the role of hippocampal limbic circuits in modulation of the stress response and the evidence which support the theory that changes in these circuits are associated with feedback abnormalities. We will review studies in humans which suggest that damage to the hippocampus can lead to changes in glucocorticoid feedback, and finally we will review the evidence that glucocorticoids themselves can lead to changes in hippocampal neurons resulting in feedback abnormalities.

Feedback↗
PubMed1997

Effect of fetal ethanol exposure on the in vitro release of growth hormone, somatostatin and growth hormone-releasing factor induced by clonidine and growth hormone feedback in male and female rats.

This study was designed to examine the effect of fetal ethanol (ETOH) exposure on the sensitivity of the hypothalamic-growth hormone (GH) axis to clonidine (an alpha 2-adrenoreceptor agonist) stimulation and GH feedback. During gestation, dams were fed either a liquid diet in which 36% of the calories were derived from ETOH, or pair-fed an isocaloric control liquid diet without ETOH. A second set of controls were fed lab chow ad libitum. After birth, offspring of ETOH-fed dams were cross-fostered to a separate group of ad libitum control dams. The hypothalami and pituitaries of 10-, 20-, 30-, and 50-day-old offspring were separated by age, diet, and sex; pooled 6 to 8 per chamber; and tested in a hypothalamic-pituitary coperifusion system. Chambers were perifused with either clonidine (2 x 10(-8) M) alone, which mimics the endogenous trigger for GH release, or clonidine in combination with human GH (2 x 10(-9) M) to determine sensitivity of tissue to feedback regulation. Both stimuli act at the hypothalamic level and indirectly modulate GH release via effects on hypothalamic factors. Results of this study indicate that tissue from control male rats is responsive to the clonidine-induced GH surge by 10 days of age and to feedback depression of GH release by 20 days of age. This sensitivity persists after puberty and is associated with corresponding changes in somatotropin-release inhibiting factor (SRIF) and GH-releasing factor (GRF) release (i.e., clonidine inhibits SRIF and stimulates GRF release, and human GH reverses this pattern). Fetal ETOH exposure depresses GH sensitivity to both stimuli in male pups (age x diet x drug: p < 0.002), and this depressed sensitivity is expressed by 30 days of age by reduced responses to alpha 2-adrenergic stimulation and GH feedback (drug x diet: p < 0.002 and p < 0.001 for 30 and 50 days of age, respectively). This effect of ETOH on GH release was associated with feedback insensitivity of SRIF (drug x diet: p < 0.003, at 50 days of age) and GRF [drug x diet; p < 0.044 at 30 days; clonidine vs. clonidine and GH: p > 0.05 (NS) at 50 days of age for ETOH pups]. The depressed response of GH to clonidine after puberty may be attributable to a combination of the trends toward decreased sensitivity of both SRIF and GRF at this age. The female GH axis was both less sensitive to stimuli and less effected by ETOH than corresponding tissue from male rats (sex x age x drug x diet: p < 0.011). GH release from control female pituitaries was sensitive to clonidine before, but not after, puberty and insensitive to GH feedback at both developmental stages. On the other hand, there was a specific effect of ETOH on SRIF release at 10 days of age (diet x drug: p < 0.014), and SRIF release remained sensitive to clonidine in pups from all diet groups after puberty. Because GH release was not influenced by these changes in SRIF, these findings suggest that GH release is less sensitive to SRIF in females. In conclusion, this study suggests that fetal ETOH exposure interferes with the development of the sensitivity of the GH axis to alpha 2-adrenergic stimulation and feedback in males. Thus, the male GH axis is both more sensitive to the stimuli tested in this study and more effected by ETOH than the female axis. Furthermore, the effects of ETOH on these mechanisms do not alter GH release in males until the peripubertal period. It is likely, therefore, that the GH regulatory mechanism examined in this study does not contribute to growth retardation before puberty. If the effects of ETOH on GH release contributes to growth retardation in prepubertal males and in females, it most likely involves other regulatory mechanisms. On the other hand, because the adult pattern of GH release is programmed during development, the influence of ETOH on these developmental events may influence the male pattern of GH release and GH activity in adulthood.

Adrenergic alpha-Agonists↗
PubMed1999

Differential subcellular localization of forward and feedback interareal inputs to parvalbumin expressing GABAergic neurons in rat visual cortex.

In rat visual cortex, forward and feedback interareal pathways innervate both pyramidal and gamma-aminobutyric acid (GABA)ergic (Johnson and Burkhalter [1996] J. Comp. Neurol. 368:383-398). GABAergic neurons consist of different cell types of which the largest group expresses parvalbumin (PV; Gonchar and Burkhalter [1997] Cereb. Cortex 4:347-358). Here, we report that PV neurons in layers 2/3 are synaptic targets of forward and feedback projections between area 17 and the lateromedial area (LM) of rat visual cortex. In both forward and feedback pathways, approximately 90% of axon terminals in layer 2/3 labeled by tracing with biotinylated dextran amine formed synapses with PV-negative profiles. In both pathways, most of these profiles resembled dendritic spines. Although there were no differences in the innervation of PV-negative targets, the two pathways differed in the innervation of PV-positive neurons. In each pathway, approximately 10% of terminals formed synapses with PV-positive profiles. However, in the forward pathway, the size of the contacted PV-positive profiles was larger than in the feedback pathway. Moreover, in the forward pathway, axon terminals on PV-positive profiles were larger, contained more mitochondria and docked synaptic vesicles than feedback synapses on PV neurons. Our results show that PV neurons provide a major target for area 17 <-> LM forward and feedback pathways terminating in upper layers. In each pathway, the proportion of axons contacting PV neurons is similar. However, both pathways differ in the subcellular localization and morphology of synapses on PV neurons. These asymmetries may contribute to the inequality in the strength of disynaptic inhibition evoked by forward and feedback inputs (Shao and Burkhalter [1996] J. Neurosci. 16:7353-7365).

Afferent Pathways↗
PubMed2000

Feedback Delays: How Can Decision Makers Learn Not to Buy a New Car Every Time the Garage Is Empty?

Decision makers in dynamic environments (e.g., stock trading, inventory control, and firefighting) learn poorly in experiments where feedback about the outcomes of their actions is delayed. In searching for ways to mitigate these effects, this paper presents two computational models of learning with feedback delays and contrasts them against human decision-makers' performance. The no-memory model hypothesizes that decision makers always perceive feedback as immediate. The with-memory model hypothesizes that, over time, decision makers are able to develop internal representations of the task that help them to perform with delayed feedback. As borne out by human subjects, both models predict that a display of past history improves learning with delay and that increasing delay increasingly degrades performance. Even though the length of training in this task exceeds that used in many laboratory-based dynamic tasks, neither the two models nor the subjects are able to effectively learn without decision aids when faced with feedback delays. When given an amount of training that more closely approximates that provided in functioning dynamic environments, the with-memory model predicts that human decision makers may learn without decision aids over the long term if feedback delays are simple. These results raise several issues for continued theoretical investigation as well as potential suggestions for training and supporting decision makers in dynamic environments with feedback delays. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Training to Improve Calibration and Discrimination: The Effects of Performance and Environmental Feedback.

This study investigated whether calibration and discrimination are distinct or related aspects of probability judgment accuracy by examining the effects of two different training techniques. Participants received either performance feedback or environmental feedback, and we measured their improvement in calibration and discrimination as a function of feedback type. Whereas performance feedback reduced participants' overconfidence and environmental feedback improved discrimination, neither type of feedback led to an improvement on the other component. In fact, environmental feedback led to an increase in overconfidence. We take these results as evidence that calibration and discrimination are dissociable abilities that require separate training techniques for improvement. Copyright 2000 Academic Press.

Journal Article↗
PubMed1978

Experimental analysis of EMG feedback in treating cerebral palsy.

Three subjects diagnosed as having severe choreoathetoid cerebral palsy were trained in the use of EMG feedback procedures. Both between- and within-session controls, including reversals of baseline, attempted muscle control with feedback, and muscle control without feedback, were employed to analyze the contribution of feedback procedures to improvements in muscle control. The data (1) indicate that feedback enhanced muscle control and (2) provide evidence of generalization of feedback effects to no-feedback conditions and untrained muscles.

Adult↗
PubMed1987

Detection of noncontingent feedback in EMG biofeedback.

Noncontingent feedback is frequently used as a placebo control procedure in biofeedback research. Researchers, however, have criticized this procedure for lacking credibility because of easy detection. The present study examined detection of false feedback in biofeedback with EMG. Contingent feedback (CF), truly random false feedback (FF), and controlled false feedback (CFF) groups were compared for changes in EMG levels, report of inaccurate feedback, and report of learning muscle activity reduction. The results indicated that FF procedures are easily detected; therefore, difference found between the FF and CF groups may be influenced by extraneous variables. The CFF group did not detect false feedback, but subjects reported some suspicions in later trials. With more trials, CFF may have also been detected. These results indicate a need for more attention to appropriate placebo control procedures in evaluating the parameters and efficacy of biofeedback.

Adult↗
PubMed1976

Control of cardiac response under aversive stimulation. Superiority of a heart-rate feedback condition.

The relative heart rate effects of biofeedback training, deep muscle relaxation, and a no-feedback/music procedure were compared during two criterion situations. The first consisted of a 25-min training period during which subjects received the assigned treatments. The second consisted of the pre- to posttraining reductions in heart rate reactivity to a series of aversive tone-shock trials. On the first criterion, the heart rate decreases of the feedback and no-feedback/music groups were not clearly distinguishable; however, both groups fell significantly below the muscle-relaxation group. By contrast, on the second criterion, the three groups were clearly distinguishable, with feedback subjects evidencing the most heart rate "control", followed by the muscle-relaxation and no-feedback/music groups, respectively. On the segment of the posttraining aversive trials conducted in the absence of the feedback signal, transfer of heart rate control was incomplete for feedback subjects, but still remained below the level of the other two groups. Training effects were more pronounced on tonic than on phasic heart rate changes. The difference between the two criterion situations suggests the possible need for and feasibility of employing a situational arousal methodology in evaluating the extent and limitation of physiological training procedures.

Adolescent↗
PubMed1979

Effects of contingent versus yoked temperature feedback on voluntary temperature control and cold stress tolerance.

Twenty-four male internals (locus of control) and 24 externals were instructed to increase finger temperature under one of three conditions: (1) contingent feedback (CF), (2) yoked sham feedback (YF), or (3) no feedback (NF). Five 13-min training sessions were given. Feedback was then removed and subjects tested for voluntary temperature control. Finally, the cold pressor test, a laboratory analogue of natural cold stress, was administered under no-feedback conditions. Results demonstrated voluntary control of peripheral temperature following contingent feedback training, but not after yoked feedback temperature training. Contrary to expectation, the acquisition of voluntary control did not attenuate the stress response to thermal pain. Differences between internals and externals throughout the study were generally insignificant.

Biofeedback, Psychology↗