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PubMed1997

Positive test strategies and confirmatory retrieval processes in the evaluation of personality feedback.

Cognitive-response analysis was carried out to investigate people's acceptance of personality feedback. In 3 studies with 223 male and female college students 18-38 years old, participants generated more confirming than disconfirming evidence for personality feedback. Availability of confirmatory evidence was found to be closely related to the rated accuracy of the feedback. Both rated accuracy and amount of confirmatory evidence were greater for general than specific and for true than false feedback. Analyses of covariance showed that availability of confirmatory evidence accounted for the effects of general versus specific and true versus false feedback on rated accuracy. Findings are discussed in terms of the use of positive test strategies and the influence of confirmatory evidence retrieval on working self-concepts.

Adolescent↗
PubMed1977

Perturbations of auditory feedback delay and the timing of movement.

Among theories concerned with the timing of movement sequences, an important distinction exists between those that assume closed-loop control (in which feedback contingent on one response starts the chain of events that leads to the next response) and those that assume open-loop control (in which feedback does not serve that function). An experiment is reported in which subjects had to make repetitive finger-tapping responses at fixed intervals of 350, 500, or 650 msec. A brief auditory signal was fed back to the subject after each response, and once in each trial, the auditory feedback delay associated with one response selected at random was perturbed by a small amount. It was found that such perturbations affected the immediately subsequent interresponse interval, which is evidence against the simple open-loop model. However, the effects, although in the same direction as the perturbation, were smaller in magnitude, a finding that rejects the simple closed-loop model. In discussing these results it is suggested that subjects operated chiefly in open-loop fashion but monitored the auditory feedback, making compensatory attempts when intervals between auditory feedback events grossly deviated from the desired interresponse interval.

Auditory Perception↗
PubMed2004

Developmental change in feedback processing as reflected by phasic heart rate changes.

Heart rate was recorded from 3 age groups (8-10, 12, and 20-26 years) while they performed a probabilistic learning task. Stimuli had to be sorted by pressing a left versus right key, followed by positive or negative feedback. Adult heart rate slowed following negative feedback when stimuli were consistently mapped onto the left or right key (response-dependent condition) but not when responses to stimuli were always followed by negative feedback (uninformative condition). Young children's heart rate showed slowing following both response-dependent and uninformative negative feedback. These findings suggest that the ability to assess the relevance of performance feedback improves with age, resulting in improved adjustment to dynamical changes in the task environment.

Adolescent↗
PubMed2003

Frontolimbic response to negative feedback in clinical depression.

Functional neuroimaging suggests that limbic regions of the medial frontal cortex may be abnormally active in individuals with depression. These regions, including the anterior cingulate cortex, are engaged in both action regulation, such as monitoring errors and conflict, and affect regulation, such as responding to pain. The authors examined whether clinically depressed subjects would show abnormal sensitivity of frontolimbic networks as they evaluated negative feedback. Depressed subjects and matched control subjects performed a video game in the laboratory as a 256-channel EEG was recorded. Speed of performance on each trial was graded with a feedback signal of A, C, or F. By 350 ms after the feedback signal, depressed subjects showed a larger medial frontal negativity for all feedback compared with control subjects with a particularly striking response to the F grade. This response was strongest for moderately depressed subjects and was attenuated for subjects who were more severely depressed. Localization analyses suggested that negative feedback engaged sources in the anterior cingulate and insular cortices. These results suggest that moderate depression may sensitize limbic networks to respond strongly to aversive events.

Adult↗
PubMed2004

Feedback specificity, exploration, and learning.

Greater feedback specificity is generally considered to be beneficial for performance and learning, but the evidence for this generalization is limited. The authors argue that increasing the specificity of feedback is beneficial for initial performance but discourages exploration and undermines the learning needed for later, more independent performance. The results of their transfer experiment demonstrate that increasing the specificity of feedback positively affected practice performance, but its benefits did not endure over time or modification of the task. In addition, feedback specificity negatively affected levels of exploration during practice and interacted with exploration strategies to affect learning. The results suggest that those who received feedback of varying specificity may have learned through different but equally beneficial mechanisms.

Adult↗
PubMed2004

Feedback specificity, learning opportunities, and learning.

Although increasing feedback specificity is generally beneficial for immediate performance, it can undermine certain aspects of the learning needed for later, more independent performance. The results of the present transfer experiment demonstrate that the effects of increasing feedback specificity on learning depended on what was to be learned, and these effects were partially mediated through the opportunities to learn how to respond to different task conditions during practice. More specific feedback was beneficial for learning how to respond to good performance and detrimental for learning how to respond to poor performance. The former relationship was partially mediated by feedback specificity's effect on learning opportunities during practice. The results have implications for designing feedback interventions and training to maximize the learning of various aspects of a task.

Adolescent↗
PubMed2005

The role of feedback information for calibration and attunement in perceiving length by dynamic touch.

Two processes have been hypothesized to underlie improvement in perception: attunement and calibration. These processes were examined in a dynamic touch paradigm in which participants were asked to report the lengths of unseen, wielded rods differing in length, diameter, and material. Two experiments addressed whether feedback informs about the need for reattunement and recalibration. Feedback indicating actual length induced both recalibration and reattunement. Recalibration did not occur when feedback indicated only whether 2 rods were of the same length or of different lengths. Such feedback, however, did induce reattunement. These results suggest that attunement and calibration are dissociable processes and that feedback informs which is needed. The observed change in variable use has implications also for research on what mechanical variables underlie length perception by dynamic touch.

Adult↗
PubMed2003

Distorted retrospective eyewitness reports as functions of feedback and delay.

Participant-witnesses viewed a crime video and attempted to identify the culprit from a culprit-absent lineup. The 253 mistaken-identification eyewitnesses were randomly given confirming, disconfirming, or no feedback regarding their identifications. Feedback was immediate or delayed 48 hr, and measures were immediate or delayed 48 hr. Confirming, but not disconfirming, feedback led to distortions of eyewitnesses' recalled confidence, amount of attention paid during witnessing, goodness of view, ability to make out facial details, length of time to identification, and other measures related to the witnessing experience. Unexpectedly, neither delaying the measures nor delaying feedback for 48 hr moderated these effects. The results underscore the need for double-blind lineups and neutral assessments of eyewitnesses' certainty and other judgments prior to feedback.

Attention↗
PubMed1982

Relationship between tubulo-glomerular feedback responses and perfusate hypotonicity.

Previous studies have established that during orthograde perfusion from a late proximal tubule site, there is a direct relationship between the magnitude of the feedback response and the level of distal tubular fluid sodium chloride concentration. The present study was conducted in the rat to extend this observation by assessing stop flow pressure (SFP) feedback responses during retrograde perfusion into the early distal tubule with solutions varying in total solute concentration and in the anionic constituent. SFP was measured after blockade of the intermediate proximal and late distal tubular segments with wax. Retrograde perfusion was initiated from an early distal tubular site at 15 nl/min. All solutions contained a 38 mOsm/kg matrix base, and the total solute concentration was increased with either sodium chloride or sodium isethionate to achieve osmolalities of 68, 85, and 120 mOsm/kg. For comparison, feedback responses during perfusion with a 120 mOsm/kg choline chloride solution were evaluated. During perfusion with the 120 mOsm/kg solutions, SFP decreased by 13 +/- 1.3 mm Hg with the sodium chloride solution, 12 +/- 1.5 mm Hg with the sodium isethionate solution, and 12 +/- 1.3 mm Hg with the choline chloride solution. During perfusion with solutions having an osmolality of 85 mOsm/kg, SFP decreased by 8 +/- 1.3 mm Hg with sodium chloride and 8 +/- 0.8 mm Hg with sodium isethionate. The 68 mOsm/kg solutions elicited decreases in SFP of 4.4 +/- 0.4 mm Hg and 5 +/- 0.5 mm Hg. During perfusion with the 38 mOsm/kg matrix solution, SFP decreased by an average of 1.4 +/- 0.9 mm Hg. Linear regression analysis revealed a 1 mm Hg decrease in SFP for every 7.7 mOsm/kg decrease in perfusate osmolality below 120 mOsm/kg. These results confirm previous findings that the magnitude of the feedback response is associated closely with the concentration of the perfusate over a narrow range from 38 to 120 mOsm/kg. Since the responses with sodium isethionate solutions were similar to the responses obtained with sodium chloride containing solutions, these studies provide evidence that the magnitude of the feedback responses are not specifically dependent on alterations in chloride concentration.

Animals↗
PubMed1985

Cyclic AMP-calcium interaction in the transmission of tubuloglomerular feedback signals.

Recent studies have suggested that cytosolic calcium serves in the transmission of signals between distal tubular fluid and glomerular vascular elements. Since cAMP can modify calcium-mediated events, it was of interest to determine if agents that elevate intracellular cAMP could influence feedback responses and to assess the interaction of cAMP and intracellular calcium in the transmission of feedback signals. Stop flow pressure (SFP) was measured in the rat during retrograde microperfusion into the distal tubule at 15 nl/min. SFP averaged 37.5 +/- 0.5 mm Hg and decreased by 12.8 +/- 0.8 mm Hg (N = 44) during perfusion with an isotonic Ringer's solution. Addition of 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor, decreased the magnitude of SFP feedback responses; 89 +/- 4.5% (N = 16) inhibition was observed at an IBMX concentration of 500 microM. In addition, SFP decreased by only 3 +/- 1 mm Hg (N = 8) during perfusion with 10 mM dibutyryl cAMP in the presence of a low concentration of IBMX and by 1.6 +/- 0.7 mm Hg (N = 12) during perfusion with forskolin, an agent that stimulates adenylate cyclase activity. Calcium ionophore (A23187) significantly increased the magnitude of SFP feedback responses obtained with IBMX alone from 5 +/- 1.0 mm Hg (N = 9; 250 micron IBMX) to 10 +/- 1.2 mm Hg (N = 11). These results indicate that agents which elevate intracellular cAMP markedly attenuate tubuloglomerular feedback responses and that calcium ionophore can reverse the inhibitory effects of increased cAMP.

1-Methyl-3-isobutylxanthine↗
PubMed2006

Noise in transcription negative feedback loops: simulation and experimental analysis.

Negative feedback loops have been invoked as a way to control and decrease transcriptional noise. Here, we have built three circuits to test the effect of negative feedback loops on transcriptional noise of an autoregulated gene encoding a transcription factor (TF) and a downstream gene (DG), regulated by this TF. Experimental analysis shows that self-repression decreases noise compared to expression from a non-regulated promoter. Interestingly enough, we find that noise minimization by negative feedback loop is optimal within a range of repression strength. Repression values outside this range result in noise increase producing a U-shaped behaviour. This behaviour is the result of external noise probably arising from plasmid fluctuations as shown by simulation of the network. Regarding the target gene of a self-repressed TF (sTF), we find a strong decrease of noise when repression by the sTF is strong and a higher degree of noise anti-correlation between sTF and its target. Simulations of the circuits indicate that the main source of noise in these circuits could come from plasmid variation and therefore that negative feedback loops play an important role in suppressing both external and internal noise. An important observation is that DG expression without negative feedback exhibits bimodality at intermediate TF repression values. This bimodal behaviour seems to be the result of external noise as it can only be found in those simulations that include plasmid variation.

Computer Simulation↗
PubMed2001

Effects of frequency-shifted auditory feedback on fundamental frequency of long stressed and unstressed syllables.

Twenty-four normally speaking subjects had to utter the test word /tatatas/ with different stress patterns repeatedly. Auditory feedback was provided by head-phones and was shifted downwards in frequency during randomly selected trials while the subjects were speaking the complete test word. If the first syllable was long stressed, fundamental frequency of the vowel significantly increased by 2 Hz (corresponding to 25.5 cents) under frequency-shifted auditory feedback of .5 octave downwards, whereas under a shift of one semitone downwards a trend of an increase could be observed. If the first syllable was unstressed, fundamental frequency remained unaffected. Regarding the second syllable, significant increases or a trend for an increase of fundamental frequency was found in both shifting conditions. Results indicate a negative feedback mechanism that controls the fundamental frequency via auditory feedback in speech production. However, within a syllable a response could be found only if the syllable duration was long enough. Compensation for frequency-shifted auditory feedback still is quite imperfect. It is concluded that control of fundamental frequency is rather important on a suprasegmental level.

Adult↗
PubMed1981

Regulation of vocal intensity in the presence of feedback filtering and amplification.

Subjects read while their voices were fed back with 0 and 20 dB of amplification. In Experiment I, feedback was returned unfiltered or low-pass filtered with cut-off frequencies of 1000, 500, and 300 Hz. Subjects decreased vocal intensity with amplified feedback when the feedback was unfiltered or low-pass filtered with cut-off frequencies of 1000 or 500 Hz. The amplification effect disappeared when the cut-off frequency was 300 Hz. In Experiment II, feedback was low-pass filtered and amplified in the presence of a steady background noise. The presence of noise potentiated the amplification effect in the unfiltered condition. When filtering was introduced and/or the cut-off frequency was lowered, the amplification effect decreased. In Experiment III, subjects heard their voices unfiltered and high-pass filtered with cut-off frequencies of 500, 1000, and 2000 Hz. The amplification effect was the same across filtering conditions. It is suggested that subjects respond differently and high- and low-pass filtering because air- and bone-conducted feedback interact differentially in these conditions. It is hypothesized that changes may be mediated by self-perception of loudness or intelligibility.

Adult↗
PubMed1996

Fluency effect of frequency alterations of plus/minus one-half and one-quarter octave shifts in auditory feedback of people who stutter.

The effect of frequency alterations in auditory feedback of people who stutter on stuttering frequency was investigated. Twelve participants who stutter read aloud under nonaltered auditory feedback (NAF) and four conditions of frequency-altered feedback ([FAF], plus/minus one-half and one-quarter octaves) at normal and fast speech rates. Stuttering frequency was significantly higher while reading aloud with NAF relative to the four conditions of FAF (p < 0.05). There were no differences among participants' stuttering frequency between the four FAF conditions (p > 0.05). Reductions in stuttering frequency of approximately 50% to 60% were found with FAF relative to NAF. More disfluencies occurred with the fast versus the normal speech rate condition (p = .0007) irrespective of auditory feedback condition. These findings suggest that slight alterations in the frequency of auditory feedback of people who stutter are fluency-enhancing.

Adult↗
PubMed2002

Involvement of GABA and cholinergic receptors in the nucleus accumbens on feedback control of somatodendritic dopamine release in the ventral tegmental area.

The objectives of the present study were to examine the involvement of GABA and cholinergic receptors within the nucleus accumbens (ACB) on feedback regulation of somatodendritic dopamine (DA) release in the ventral tegmental area (VTA). Adult male Wistar rats were implanted with ipsilateral dual guide cannulae for in vivo microdialysis studies. Activation of the feedback system was accomplished by perfusion of the ACB with the DA uptake inhibitor GBR 12909 (GBR; 100 microm). To assess the involvement of GABA and cholinergic receptors in regulating this feedback system, antagonists (100 microm) for GABAA (bicuculline, BIC), GABAB (phaclofen, PHAC), muscarinic (scopolamine, SCOP), and nicotinic (mecamylamine, MEC) receptors were perfused through the probe in the ACB while measuring extracellular DA levels in the ACB and VTA. Local perfusion of the ACB with GBR significantly increased (500% of baseline) the extracellular levels of DA in the ACB and produced a concomitant decrease (50% of baseline) in the extracellular DA levels in the VTA. Perfusion of the ACB with BIC or PHAC alone produced a 200-400% increase in the extracellular levels of DA in the ACB but neither antagonist altered the levels of DA in the VTA. Co-perfusion of either GABA receptor antagonist with GBR further increased the extracellular levels of DA in the ACB to 700-800% of baseline. However, coperfusion with BIC completely prevented the reduction in the extracellular levels of DA in the VTA produced by GBR alone, whereas PHAC partially prevented the reduction. Local perfusion of the ACB with either MEC or SCOP alone had little effect on the extracellular levels of DA in the ACB or VTA. Co-perfusion of either cholinergic receptor antagonist with GBR markedly reduced the extracellular levels of DA in the ACB and prevented the effects of GBR on reducing DA levels in the VTA. Overall, the results of this study suggest that terminal DA release in the ACB is under tonic GABA inhibition mediated by GABAA (and possibly GABAB) receptors, and tonic cholinergic excitation mediated by both muscarinic and nicotinic receptors. Activation of GABAA (and possibly GABAB) receptors within the ACB may be involved in the feedback inhibition of VTA DA neurons. Cholinergic interneurons may influence the negative feedback system by regulating terminal DA release within the ACB.

Animals↗
PubMed2001

Improving benzodiazepine prescribing for elderly hospital inpatients using audit and multidisciplinary feedback.

BACKGROUND: Benzodiazepines are commonly prescribed for older people. Inappropriate benzodiazepine prescribing may result in serious adverse effects, including confusion and falls. AIMS: To determine the prevalence and appropriateness of benzodiazepine prescribing for elderly inpatients at nine public hospitals in Victoria, Australia, and to assess the impact of multidisciplinary feedback on quality of benzodiazepine prescribing. METHODS: Clearance for the study was obtained from ethics committees of participating hospitals. Medication charts for 1301 patients aged 65 years and over were reviewed to identify patients prescribed a benzodiazepine. Using an evidence-based indicator of prescribing appropriateness, cross-sectional notes-based audits were conducted at three time points (baseline, 4-8 weeks and 6 months). Feedback of baseline audit results was provided to medical, pharmacy and nursing staff at multidisciplinary meetings. Changes in benzodiazepine prescribing over the following 6 months were assessed. RESULTS: At baseline, benzodiazepines were prescribed for 36% of patients, and 20% of prescriptions were appropriate. Four to six weeks after feedback, the proportion of patients prescribed a benzodiazepine had not changed significantly (31%, P = 0.125); however, more prescriptions were appropriate (44%, P < 0.0001). For patients who were using a benzodiazepine prior to admission and had a contraindication, there were more attempts to withdraw or reduce the dose (47% vs 21%, P = 0.002) and more prescriptions were for acceptable indications (7.4% vs 2.6%, P = 0.024). Six months after feedback, appropriateness of prescribing remained improved compared with baseline (50%, P = 0.002). CONCLUSIONS: Benzodiazepines were prescribed for approximately one in three elderly hospital inpatients and a large proportion was inappropriate. A multidisciplinary intervention based on audit and feedback improved prescribing and the impact of the intervention was still evident after 6 months.

Aged↗
PubMed1997

Primary care physicians' use of lumbar spine imaging tests: effects of guidelines and practice pattern feedback.

OBJECTIVE: To reduce variability in primary care physicians' use of procedures for imaging the lumbar spine. DESIGN: Controlled intervention using clinical practice guideline and practice pattern feedback. STUDY SAMPLE: Sixty-seven internists and 28 family practitioners in a large, group-model HMO. MEASUREMENTS AND MAIN RESULTS: Intervention group physicians received the clinical practice guideline for low back pain, followed after 4 months by three bimonthly feedback reports on their current use rates for lumber spine x-rays and computed tomography and magnetic resonance imaging scans of the lumbar spine. Control group physicians received neither the guideline nor the feedback reports. Automated radiology utilization data were used to compare intervention and control group physicians' changes in use rates and variability in use rates over the course of the study period. Neither the guideline alone nor the guideline plus feedback was associated with a significant decrease in use rates or in the variability in use rates for the lumbar spine imaging procedures under study. CONCLUSIONS: Clinical practice guidelines and practice pattern feedback fail to achieve their goals when features of the practice setting and patient expectations and behavior are not identified and addressed.

Adolescent↗
PubMed1996

[Estrogen feedback tests in women with laryngeal carcinomas].

BACKGROUND: The high incidence ratio males to females is the reason for considering a hormonal dependency of these tumours for many years. The low incidence of laryngeal cancer in women has generally been suggested as being due to "oestrogen defense". Although we do have some circumstantial evidence in the meantime, no final evidence on this topic is available so far. METHODS: The oestrogen feedback effect could be another more objective parameter to bring more light to the research of this question. As one of the regulation mechanisms of the hypothalamic-pituitary-adrenal axis the oestrogen feedback mechanism represents the regulation of LH and FSH production in the pituitary gland by peripheral oestrogens. The mechanism is known to exist lifelong under normal conditions. Whereas the positive oestrogen feedback is typical for women, a negative response pattern is mostly found in men. The positive response pattern is characterised by increasing LH values, higher than the starting level, on the 3 th and 4 th day after intravenious application of oestrogens. RESULTS: The results of the present investigation show some difference. 5 of 6 examined women with laryngeal cancer were found to have a clearly negative oestrogen feedback, whereas 4 of 5 healthy women had a positive oestrogen feedback effect. 5 healthy men showed the typical negative effect for men. CONCLUSION: We may assume a narrow relationship between the male regulation type and the occurrence of laryngeal cancer in women, if further trials including more patients are able to reproduce these results.

Adult↗