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PubMedDate not supplied

[Perception of musical sounds: contributions of positron emission tomography].

The perception of music is not a single global process. It encompasses the integration into conscience of various elements, such as sound pitch, tone, rhythm and impression of familiarity. Thus, it may be subjected to cognitive studies based on specific and complementary abilities of both cerebral hemispheres in these tasks. A number of selected medical cases reported previously had already suggested anatomic-clinical correlations for the perception of the various components of musical sounds. The left hemisphere subserves rhythm and pitch perception, the sense of familiarity and identification of a musical piece. The right hemisphere plays a part in the perception of tone and melodic line. Position emission tomographic studies in normal subjects have corroborated these assumptions on hemispheric lateralization in musical perception. In addition, they have demonstrated previously unsuspected facts, such as the role of visual areas in pitch perception and the role of frontal cortex and especially of Broca's area in the perception of rhythm.

Auditory Perception↗

PubMed2001

Perception viewed as an inverse problem.

The modern study of perception began when Fechner published his 'Elements of Psychophysics' in 1860. This book has guided most perception research ever since. It has become increasingly clear that there are problems with Fechner's approach, which assumes that the percept is completely determined by the sensory input. Fechner's approach cannot explain the processes that allow our percepts to be veridical. Post-Fechnerian schools (Helmholtzian, Structural, Gestalt and Gibsonian) have tried to deal with this problem, but have not been successful. An alternative to the Fechnerian approach is required. This paper describes an alternative that has been developing over the last 20 years within the computer vision community. It treats perceptual interpretation as a solution of an inverse problem that depends critically on the operation of a priori constraints. Contemporary research, which adopted this approach, has concentrated on verifying the usefulness of Bayesian and standard regularization methods. This paper takes the next step; it discusses theoretical and empirical aspects of studying human perception as an inverse problem. It reviews the literature that illustrates the power of the inverse problem approach. This review leads to the suggestion that progress in the study of perception will benefit if the inverse approach were to be adopted by experimentalists, as well as by the computational modelers, who have been actively exploring its potential to date.

Bayes Theorem↗

PubMed2006

The role of intensity upon pitch perception in cochlear implant recipients.

OBJECTIVES: Pitch plays a key role in the perception of speech and music, the recognition of a speaker's voice, and in analyzing complex auditory patterns. To date, little consideration has been given to the influence of stimulation level on pitch perception. The aim of this study was to investigate the impact of a sound's intensity on pitch perception in cochlear implant recipients using monopolar stimulation. STUDY DESIGN: Thirteen patients with an average implant use of 4.13 years took part in this study. All patients were implanted with MedEl Combi 40/40+ cochlear implants. METHODS: In the first part of the study, we performed a pitch ranking procedure to confirm that all patients were able to judge pitch changes. Using a visual scale, study participants were then asked to compare the pitch of an intensity-constant reference tone with the pitch of a test tone of varying intensity. RESULTS: Eleven (85%) patients were found to perceive a clear change in pitch with changing stimulus intensity. Statistical analysis showed a strong positive correlation in 10 patients (correlation coefficients between 0.99 and 0.71) and a strong negative correlation in 1 patient (r = -0.92). CONCLUSIONS: The results suggest that a distinct relationship exists between pitch perception and intensity of the stimulus. To date, speech coding strategies do not support these findings. Nevertheless, we believe that for the optimized most natural perception of sounds, especially music, the described particularities of pitch perception need to be respected, and further investigations on this topic are necessary.

Acoustic Stimulation↗

PubMed1990

Physician behaviors, patient perceptions, and patient characteristics as predictors of satisfaction of hospitalized adult cancer patients.

To examine potential predictors of cancer patient satisfaction with physician behavior, 366 cases were studied. Physician behavior was measured on morning rounds using the Physician Behavior Check List (PBCL). Patient satisfaction and perceptions were assessed after the visit. Patient characteristics were obtained from the chart and the physician. Results showed wide variation in physician behavior; no "standard" set of behaviors was seen in all interactions. Patient satisfaction was high (mean = 87.8 mm on a 100-mm scale). Path analysis showed four variables predicted 62% of the variance in patient satisfaction. The strongest predictor was the patient perception item, "perception of needs addressed that day." Other predictors were perception of emotional support provided by the physician, age (older), and one physician behavior, "discusses treatment." Patient perceptions of needs met or emotional support provided were predicted by perceptions of the occurrence of physician behaviors involving information such as the diagnosis and tests and treatment. Overall, patient perceptions of physician behaviors were stronger predictors of patient satisfaction than the actual occurrence or absence of those behaviors.

Consumer Behavior↗

PubMed1991

Perception of forearm angles in 3-dimensional space.

The purpose of this study was to determine a preferred coordinate system for representation of forearm orientation in 3-dimensional space. In one experiment, the ability of human subjects to perceive angles of the forearm in 3-dimensional space (forearm elevation and yaw--extrinsic coordinate system) was compared to their ability to perceive elbow joint angle (intrinsic coordinate system). While blindfolded, subjects performed an angle reproduction task in which the experimenter first positioned the upper limb in a reference trial. This was followed, after movement of the subject's entire upper limb to a different position, by an attempt to reproduce or match a criterior angle of the reference trial by motion of the forearm in elbow flexion or extension only. Note that matching of the criterion forearm angle in the new upper limb position could not be accomplished by reproducing the entire reference upper limb position, but only by angular motion at the elbow. Matching of all 3 criterion angles was accomplished with about equal accuracy in terms of absolute constant errors and variable errors. Correlation analysis of the perceptual errors showed that forearm elevation and elbow angle perception errors were not biased but that forearm yaw angle matching showed a bias toward elbow angle matching in 7 of 9 subjects. That is errors in forearm yaw perception were attributed to a tendency toward a preferred intrinsic coordinate system for perception of forearm orientation. These results show that subjects can accurately perceive angles in both extrinsic and intrinsic coordinate systems in 3-dimensional space. Thus, these data conflict with previous reports of highly inaccurate perception of elbow joint angles in comparison to perception of forearm elevation. In an attempt to resolve this conflict with previous results, a second experiment was carried out in which perception of forearm elevation and elbow joint angles with the forearm motion constrained to a vertical plane. Results of this experiment showed that during a two-limb elbow angle matching task, four of five subjects exhibited a clear bias toward forearm elevation angle. During a one-limb angle reproduction task only two of five subjects exhibited such a bias. Perception of elevation angles show little bias toward elbow angle matching.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1984

The effect of smoking on perception of muscle tension.

It has been suggested that smoking may reduce affect in high-arousal situations by blocking peripheral physiological cues. The effects of smoking on perception of one type of physiological response, muscle activity, was evaluated in two studies. In study 1 male and female smokers were exposed to four conditions: high and low arousal crossed with smoking or deprivation. Results showed that smokers produce less muscle activity during high- than low-arousal situations, and that smoking reduced sensitivity to muscle activity in females, but enhanced it in males. These perception differences were not related to arousal as assessed by heart rate, which was elevated in all high-arousal situations. When compared to nonsmokers, smokers in a deprived state generate more muscle activity during the perception task, but showed no differences in sensitivity. These results represent the initial demonstration that smoking can alter the perception of physiological processes. Study 2 was designed to determine whether the effects of smoking were specific to muscle tension or indicative of a more generalized perceptual change. Perception of muscle tension and decibel levels were compared in smoking or deprived female smokers who were in the high-arousal situation. Results for muscle-tension perception in high-arousal situations were similar to those in study 1, but smoking did not alter perception of auditory stimuli.

Adolescent↗

PubMed2002

Percept-related changes in horizontal optokinetic nystagmus at different body orientations in space.

Large-field motion of the visual environment is a powerful stimulus to induce the perception of contra-directional self-motion in a stationary observer. We investigated the interrelations between horizontal optokinetic nystagmus and subjective states of motion perception under variation of subjects' orientation with respect to gravity. Subjects were tested sitting upright and lying supine, and signalled transitions between object- and self-motion perception whilst viewing an optokinetic stimulus rotating about the subjects' longitudinal axis at a range of angular velocities. Optokinetic stimulation in the supine condition resulted in subjects perceiving a graviceptive conflict and the illusory perception of whole body tilt in a direction opposite to optokinetic stimulus rotation, whereas during upright viewing the axis of stimulus rotation was aligned with the direction of gravity and thus did not result in a conflict or perception of tilt. In both postures, self-motion perception coincided with an increased deviation of mean horizontal gaze position in the perceived direction of heading with a concurrent reduction in optokinetic nystagmus slow-phase gain. Slow-phase gain was also significantly reduced in the supine position as well as at increasing stimulus velocities. The results demonstrate that spontaneous transitions between the perception of object-motion and that of self-motion consistently coincide with spatial attentional and orientational strategies, shifting from passive monitoring to active oculomotor exploration and anticipation.

Adult↗

PubMed2000

Gaze direction effects on perceptions of upper limb kinesthetic coordinate system axes.

The effects of varying gaze direction on perceptions of the upper limb kinesthetic coordinate system axes and of the median plane location were studied in nine subjects with no history of neuromuscular disorders. In two experiments, six subjects aligned the unseen forearm to the trunk-fixed anterior-posterior (a/p) axis and earth-fixed vertical while gazing at different visual targets using either head or eye motion to vary gaze direction in different conditions. Effects of support of the upper limb on perceptual errors were also tested in different conditions. Absolute constant errors and variable errors associated with forearm alignment to the trunk-fixed a/p axis and earth-fixed vertical were similar for different gaze directions whether the head or eyes were moved to control gaze direction. Such errors were decreased by support of the upper limb when aligning to the vertical but not when aligning to the a/p axis. Regression analysis showed that single trial errors in individual subjects were poorly correlated with gaze direction, but showed a dependence on shoulder angles for alignment to both axes. Thus, changes in position of the head and eyes do not influence perceptions of upper limb kinesthetic coordinate system axes. However, dependence of the errors on arm configuration suggests that such perceptions are generated from sensations of shoulder and elbow joint angle information. In a third experiment, perceptions of median plane location were tested by instructing four subjects to place the unseen right index fingertip directly in front of the sternum either by motion of the straight arm at the shoulder or by elbow flexion/extension with shoulder angle varied. Gaze angles were varied to the right and left by 0.5 radians to determine effects of gaze direction on such perceptions. These tasks were also carried out with subjects blind-folded and head orientation varied to test for effects of head orientation on perceptions of median plane location. Constant and variable errors for fingertip placement relative to the sternum were not affected by variations in gaze direction or head orientation. Thus, the perceived position of the trunk-fixed median plane is not altered by varying gaze direction. The implications of these results for mechanisms underlying kinesthetic perceptions and their potential roles in programming of upper limb movements to visual targets are discussed.

Adult↗

PubMed2006

Factors affecting patients' perceptions of choice regarding adjuvant chemotherapy for breast cancer.

INTRODUCTION: Patients' perceptions of having had freedom of choice in treatment decision-making are shown to have implications for their quality of life. It is, therefore, important to determine what factors underlie these perceptions. One factor that has been studied is whether or not patients believed that their doctor had offered choice of treatment. However, even when choice is actually offered, patients may still feel that they have no choice. Little attention has been paid to other factors that may contribute to patients' perceptions of having had no choice. Our purpose was to explore (1) whether early-stage breast cancer patients perceived to have had a choice with regard to adjuvant chemotherapy, and (2) their reasons for having perceived no choice. PATIENTS AND METHODS: The determinants of no choice that we examined were: (1) (preferred) involvement in treatment decision-making, (2) perceived clinical benefits of chemotherapy (e.g., cure), (3) perceived psychological benefits (e.g., less worries), and (4) perception of being able to cope with the side effects. All predictors, as well as patient and clinical characteristics, were entered simultaneously in a multiple logistic regression analysis and non-significant predictors were removed step-by-step, until only significant predictors (p<0.05) remained. Because determinants may differ between patients with experience of chemotherapy and those without, both treatment groups were analyzed separately. RESULTS: Four hundred and forty-six patients filled out the questionnaire (62%). Sixty-six percent of patients who had been treated with chemotherapy and 86% of inexperienced patients had perceived no treatment choice. In both treatment groups, patients who preferred a shared role or a passive role in treatment decision-making were statistically significantly more likely to have perceived no treatment choice than patients who preferred an active role. Surprisingly, beliefs about the clinical and psychological benefits of chemotherapy did not influence patients' perceptions of having had choice of treatment. CONCLUSION: If we adhere to patient autonomy and shared decision making, we may consider the perception of no treatment choice as a negative outcome of treatment decision-making. However, if this is the result of the patients' preference for less active involvement in treatment decision-making, the topic of perception of no treatment choice may be viewed in a different light.

Adult↗

PubMed1994

Psychological aspects of pain perception.

Interest in the assessment and management of pain increased dramatically after 1965, when the gate control theory was introduced. This increase is concurrent with enormous advances in our understanding of the plasticity and complexity of pain processing. New information about internal pain-inhibitory systems and the factors that trigger them has revolutionized traditional approaches to pain control. This article describes some of the new information on the factors that influence human pain perception, specifically the environmental and psychological factors that modify how pain is experienced. Pain is a complex, multidimensional perception that varies in quality, strength, duration, location, and unpleasantness. The strength and unpleasantness of pain is neither simply nor directly related to the nature and extent of tissue damage. Even newborn infants may experience different pains from the same stimulus, because of the differences in the situations in which it is administered. Pain experiences can range from an inability to perceive pain, regardless of the strength of stimulation, to the actual perception of pain in a limb that has been amputated. The perception of, expression of, and reaction to pain are influenced by genetic, developmental, familial, psychological, social and cultural variables. Psychological factors, such as the situational and emotional factors that exist when we experience pain, can profoundly alter the strength of these perceptions. Attention, understanding, control, expectations, and the aversive significance can affect pain perceptions. Consequently, the understanding of pain requires not only understanding of the nociceptive system, but recognition and control of the many environmental and psychological factors that modify human pain perceptions.

Acute Disease↗

PubMed1995

Perception and reflex responses to intestinal distention in humans are modified by simultaneous or previous stimulation.

BACKGROUND & AIMS: Intestinal reflexes induced by distention in dogs are facilitated by either simultaneous or previous distentions. The aim of this study was to determine whether these phenomena also modulate the responses to intestinal distention, particularly perception, in humans. METHODS: Perception and intestinal relaxation were measured in 11 healthy subjects in response to increasing jejunal balloon distentions tested (by stimulus-response trials) alone, as control, and with conditioning distentions applied either simultaneously, immediately (10 seconds) before at the same site, or immediately before and 5 cm distant. In 8 additional subjects, the effect of prolonged (90-minute) conditioning distention was tested. RESULTS: Conditioning had more pronounced effects on perception than on intestinal reflexes. Perception of intestinal distention increased (by 84 +/- 47%; P < 0.05) when a simultaneous distention was applied nearby. By contrast, perception decreased (by 38 +/- 12%; P < 0.05) when a previous distention was applied at the same but not at an adjacent site. Prolonged intestinal distention elicited remarkably stable perception during a 90-minute period. The effects of conditioning were unrelated to intestinal compliance because it remained unchanged. CONCLUSIONS: In humans, temporospatial interactions of gut stimuli activate modulatory phenomena that determine the perception intensity of the stimuli.

Adult↗

PubMed2006

Illness perceptions predict attendance at cardiac rehabilitation following acute myocardial infarction: a systematic review with meta-analysis.

OBJECTIVE: Early reports indicated that the illness perceptions of patients following acute myocardial infarction (AMI) predict attendance at cardiac rehabilitation. However, null findings have subsequently been reported, and there is variation between studies in terms of which illness perception constructs predict attendance. The aim of this meta-analysis was to examine whether illness perceptions really predict attendance at cardiac rehabilitation and to examine factors that moderate this relationship. METHODS: The strategy and procedures recommended by Hunter and Schmidt [Hunter JE, Schmidt FL. Methods of meta-analysis: correcting error and bias in research findings. Thousand Oaks (CA): Sage, 2004] were followed. Based on a systematic literature search, eight studies (N=906 patients) that examined the relationship between illness perceptions and attendance at cardiac rehabilitation were included. RESULTS: Four illness perception constructs significantly predicted attendance at cardiac rehabilitation: patients with more positive identity (r=.123), cure/control (r=.111), consequences (r=.081), and coherence (r=-.160) beliefs were more likely to attend cardiac rehabilitation. For all relationships, except that between cure/control beliefs and rehabilitation attendance, there was significant heterogeneity, which was attributable to two studies: one that assessed illness perceptions after leaving the hospital yielded higher effect size estimates, whereas another that involved an intervention yielded effect size estimates in the direction opposite to those of most other studies. The exclusion of these studies resulted in largely unchanged, but homogeneous, effect size estimates. CONCLUSION: Illness perceptions of AMI patients predict attendance at cardiac rehabilitation, although the effect sizes are small and often heterogeneous. AMI patients who view their condition as controllable, as symptomatic, and with severe consequences, and who feel that they understand their condition are more likely to attend.

Attitude to Health↗

PubMed1999

Gastric wall tension determines perception of gastric distention.

BACKGROUND & AIMS: The primary mechanism that originates symptoms in response to gastric distention remains undefined. The aim of this study was to determine which factor, whether intragastric volume, pressure, or wall tension, determines perception of gastric distention. METHODS: Healthy subjects underwent increasing gastric distentions (2-minute duration at 5-minute intervals) either at fixed pressure levels using a conventional barostat (n = 10) or at fixed tension levels using a newly developed computerized tensostat (n = 12); perception was scored by a 0-6 scale. Distentions were performed during basal conditions (intravenous saline) and during gastric relaxation by glucagon administration (4.8 microgram/kg intravenous bolus plus 9.6 microgram. kg-1. h-1 infusion). RESULTS: Isobaric distentions with the conventional barostat produced more intense perception during glucagon (95% +/- 40% higher; P < 0.05). However, the factor that determined higher perception could not be ascertained, because at the same pressure levels both intragastric volume and wall tension were greater during glucagon administration (174% +/- 56% and 34% +/- 8% greater, respectively; P < 0.05 vs. saline for both). The tensostat evidenced that perception was selectively related to tension, not to elongation; during glucagon administration, intragastric volumes were significantly larger (80% +/- 28% larger increase; P < 0.05), but perception of isotonic distentions remained the same (27% +/- 22%; nonsignificant change). CONCLUSIONS: Gastric wall tension, but not intragastric volume, determines perception of gastric distention, at least below nociception.

Adult↗

PubMedDate not supplied

Motion perception in glaucoma patients: a review.

Most of the histopathological and psychophysical studies in glaucoma reveal a preferential damage to the magnocellular (M) pathway although a few of them support a damage to the parvocellular (P) pathway as well. In glaucoma, the visual fields are usually evaluated by conventional perimetry. However, it has been demonstrated that 20-40% of ganglion cells are lost before field defects are detected using conventional perimetry. Therefore, new psychophysical tests have recently been designed in order to specifically isolate and evaluate the visual mechanisms that are impaired at the early stages of glaucoma. In this context, several authors have addressed the issue of motion perception under the hypothesis of a predominant damage of the M pathway in glaucoma, and that motion perception is mediated mainly by M pathway. The results of these studies depict a large variation in the percentage of patients showing anomalous motion perception. Overall, motion thresholds are elevated in both glaucoma and ocular hypertensive patients as compared to control subjects, irrespective of the stimulus size and eccentricity. The test which discriminates best between patients and normal subjects is motion perimetry. The visual field defects in glaucoma patients identified by conventional perimetry and motion perimetry are similar, but the sizes of the defects are usually larger with motion perimetry. However, motion tests in central vision have no correlation with visual field defect on conventional perimetry. In glaucoma, loss of performance on motion perception tests does not necessarily support the existence of a specific deficit in the M pathway, because some behavioral studies suggest that the P pathway can also mediate motion perception. It is also difficult to conclude that motion perception is specifically affected in glaucoma because most of these studies do not yield a comparison with other visual functions. Despite these difficulties, localized motion perception tests at eccentricities of more than 15 degrees can be considered as a promising diagnostic tool.

Glaucoma, Open-Angle↗

PubMed2003

Scaling of letter size and contrast equalises perception across eccentricities and set sizes.

Double E(2)N(2) scaling, i.e. magnifying size and contrast, allows modelling of the deterioration of face recognition performance with increasing eccentricity (E) and the size (N) of the set from which a target face has to be identified. E(2) and N(2) values represent the eccentricities and set sizes at which stimulus size and contrast must double in order to keep performance unchanged, whilst parameter K represents the multiplicative interaction between E and N. In the current study we investigated whether double E(2)N(2) scaling can model performance deterioration with increasing eccentricity and set size in letter perception too. Contrast sensitivity for letter perception was investigated as a function of letter size at N=1-8 and E=0 degrees -10 degrees. The superimposition of contrast sensitivity functions produced two scaling surfaces, one for letter size and another for contrast, which allowed modelling of the changes in letter perception with increasing E and N. With increasing eccentricity/set size the change of scale was much faster for contrast than letter size. Thus, in letter perception, contrast scaling was more important than spatial scaling. When compared with face perception, the change of spatial scale with increasing eccentricity was slower for letters whereas the change of contrast scale was similar for both. With increasing set size the changes of both spatial and contrast scales are faster for faces. In spatial scaling the interaction between eccentricity and set size was similar for letters and faces whereas in contrast scaling letters showed no interaction. Thus, letter perception was less affected by eccentricity and set size than face perception.

Adult↗

PubMed1998

Rectification nonlinearity in cortical end-stopped perceptive fields.

End-stopped perceptive fields associated with line targets were demonstrated previously with length and width Westheimer functions. In this study we investigated rectifying non-linearity in these perceptive fields to examine whether they directly reflect the organization of cortical receptive fields. Specifically, we reversed the polarity of parts of the background field associated with a specific perceptive field sub-region and examined threshold changes in corresponding length or width Westheimer functions. Results showed full-wave rectification in end-stopping and half-wave rectification in center summation and flank-inhibition preceding linear summation in end-stopped perceptive fields. Half-wave rectification in center summation and surround-inhibition preceding linear summation was also found in circular perceptive fields associated with spot targets. These results are inconsistent with direct links between perceptive fields and cortical receptive fields. Rather they suggest that these perceptive fields are likely the second-order fields formed by pooled non-linearly rectified outputs from cortical receptive fields.

Adult↗

PubMed2003

Environmental measures of physical activity supports: perception versus reality.

BACKGROUND: Perceptions of the environment and physical activity have been associated using survey methods, yet little is known about the validity of environmental surveys. In this study, perceptions of the environment at neighborhood and community levels were assessed (1) to determine validity by comparing respondent perceptions to objective measures and (2) to determine test-retest reliability of the survey. METHODS: A telephone survey was administered to a stratified sample of Sumter County, South Carolina adults. Respondents' home addresses were mapped using a geographic information system (GIS) (n =1112). As an indicator of validity, kappa statistics were used to measure agreement between perceptions and objective measures identified at neighborhood and community levels using GIS. A second survey in an independent sample (n=408) assessed test-retest reliability. RESULTS: When assessing perceptions of environmental and physical activity in a defined geographic area, validity and reliability for neighborhood survey items were kappa= -0.02 to 0.37 and rho=0.42 to 0.74, and for community survey items were kappa= -0.07 to 0.25 and rho=0.28 to 0.56. CONCLUSIONS: Although causality between perception of access and safety and actual physical activity level cannot be assumed, those meeting national physical activity guidelines or reporting some physical activity demonstrated greatest agreement with access to recreation facilities, while those not meeting the guidelines demonstrated greater agreement with safety of recreation facilities. Factors such as distance and behavior may explain differences in perceptions at neighborhood and community levels. Using local environments with short distances in survey methods improves validity and reliability of results.

Adult↗

PubMedDate not supplied

Altered perceptions after upper and lower extremity blocks: an initial investigation.

BACKGROUND AND OBJECTIVES: Nerve blocks frequently produce unusual altered perceptions in the extremities. We examined perceptual changes experienced after peripheral blocks. METHODS: Fifty consecutive patients having an upper or lower extremity block for surgery participated in this prospective study. Patients were divided into 2 groups: upper extremity (n = 20) and lower extremity (n = 30). Each group was asked a list of questions about perceptions of limb sensation, length, weight, and location and given a detailed 2-point discrimination test over the V(1)-V(3) divisions of the trigeminal nerve prior to block and sedation. While the extremity was still blocked, the exam was repeated before postanesthesia care unit discharge. RESULTS: In both groups, 98% of patients described altered limb perception. The perceptions in the upper extremity were: heaviness, 60%; numbness, 50%; warmth, 40%; pain, 30%; full or fat, 20%; floating, 5%; shorter, 0%; or thinner, 10%. The perceptions in the lower extremity were: numbness, 75%; heaviness, 46%; warmth, 33%; pain, 32%; full or fat, 36%; floating, 25%; shorter, 18%, or thinner, 7%. Upper extremity block patients were more likely to describe the limb as lighter (P <.0001); the lower extremity group was more likely to describe the limb as numb (P =.01) or floating (P =.0002). There was no difference in the ability to correctly identify the location of the limb between the groups. There was no difference in 2-point discrimination between each assessment for either group. CONCLUSION: The results of this study confirm and quantify the perceptions experienced by patients undergoing upper and lower extremity blocks. These perceptions are prevalent. This knowledge is helpful in providing patients with accurate preoperative preparation. Further investigation is warranted to determine the neurologic etiology of these observations.

Adult↗