Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Weight Perception”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed2003

Self-pacing and cognitive performance while walking.

Ten hikers completed a 4 km hike on hilly terrain three times: once self-paced without load, once self-paced with a backpack load of 10% body weight, and once externally paced with a backpack load of 10% body weight. Subjects performed mental arithmetic tasks and provided ratings of perceived exertion while walking. No differences in speed or accuracy of performance of mental arithmetic problems were observed. A battery of cognitive and physical tests was performed prior to walking and after each of the three walks. Significant differences between pre-walk baselines and post-walk tests were found only for the pattern-matching task. Subjects altered their pace in response to the addition of the backpack load, and altered their speed on downhill terrain in response to external pacing. Ratings of perceived exertion were found to correlate relatively well (r = 0.80) with heart rate, but consistently underestimated actual heart rate. Underestimation was much greater for downhill than for uphill terrain. Underestimation of heart rate by rating of perceived exertion was least when subjects carried an external load of 10% body weight.

Adolescent↗
PubMed2000

Psychophysical and psychosocial comparison of squat and stoop lifting by young females.

Psychophysical and psychological criteria are accepted risk measures for manual handling task assessment, yet few reports have compared squat and stoop using these criteria. Seventeen university students participated in a within-subjects cross over design study to compare squat and stoop techniques using maximum acceptable weight (MAW), perceptions of exertion (RPE), discomfort and preference. Mean (SD) MAW for squat was lower than for stoop (7.0 (2.2) kg vs 8.5 (2.4) kg) and RPE for squat was greater than for stoop (15.2 (1.5) kg vs 13.3(1.5) kg). More subjects reported discomfort following squat and a preference for stoop. The results provide limited support for use of stoop rather than squat technique for lifting a medium sized box from floor to knuckle height.

Journal Article↗
PubMed1999

Affordance, proper function, and the physical basis of perceived heaviness.

The physical basis of perceived heaviness requires consideration of the haptic perceptual system's role in controlling actions (the system's proper function) and the relation of an object's inertial properties to properties of the human movement system (the object's affordance). We show that the mass of a wielded object and particular scalar variables calculated from the object's inertia tensor combine linearly in determining perceived heaviness. The tensor-derived scalars reflect the symmetry and volume of the corresponding inertia ellipsoid. These measures bear directly on the object's wieldability, that is, on the patterning and level of muscular forces required to move the object in a controlled fashion.

Adult↗
PubMed2006

Sense of motor effort in patients with schizophrenia.

We tested the hypothesis suggesting that internally generated signals related to motor command would not be processed in schizophrenic patients with first rank symptoms (FRS). To address this question, we investigated an aspect of the efference copy not yet investigated in schizophrenia, namely its implication in sensation of effort. We assessed sensation of effort in healthy subjects (n = 17) and in schizophrenic patients with (n = 6) and without (n = 11) FRS using two tasks. In the first, subjects were required to produce isometric target-forces under visual control with one hand (reference hand), and then, without external feedback, to transfer the same effort to the other hand (matched hand). In the second, subjects had to produce force impulses whose magnitude was proportional to numerical values. The results of the first experiment showed that all subjects could maintain a significant relationship between the force exerted by the reference hand and the force exerted by the matching hand. Results from the second experiment indicated that the strength of the relationship between desired efforts and achieved peak forces was lower in both patient groups compared to controls. Taken together our findings indicate that one component of efference copy--its implication in sensing achieved effort--is preserved in schizophrenia. We propose that schizophrenic patients and particularly those with FRS are impaired in the ability to represent intended effort. The detection threshold of centrally generated signals by the higher order level of the motor representation may be abnormally high in these patients.

Adult↗
PubMed2000

Weighing the evidence for cross over in neglect.

When patients with left-sided neglect are asked to bisect horizontal lines, they tend to place their marks to the right of the line's objective mid-point. However, when asked to bisect short lines they are either more accurate or paradoxically cross over and place their marks to the left of the objective mid-point. Previous explanations of the cross over phenomenon have considered specific aberrations of spatial attention. However, these explanations make no predictions about judgments of non-spatial stimuli. Two patients with right brain damage were asked to judge weights placed on both hands simultaneously. They were biased in reporting weights on the right as being heavier than those on the left. This rightward bias changed with lighter pairs of weights presented in the context of equal reference weights. In one patient the directional bias was eliminated and in the other the bias was reversed so that she was more likely to report the left weight as heavier than the right. These data suggest that a phenomenon analogous to cross over in line bisections also occurs with judgments of non-spatial stimuli. Representations of stimuli appear to be influenced by features of the stimuli encountered on-line and by memory traces of similar stimuli encountered previously. With an attentional deficit, memory traces influence the magnitude of the representation derived on-line disproportionately.

Aged↗
PubMed2002

Sensation of effort is altered in Huntington's disease.

In this study, we investigated sensation of effort in Huntington disease (HD). We tested the hypothesis that the basal ganglia are involved in processing effort sensation. The experimental paradigm consisted in a contralateral matching procedure where normal subjects (N=6) and HD patients (N=6) were required to lift a reference weight with their non-dominant index, and then compare the target-weight with variable weights lifted by the dominant index. Two kinds of sequences were administered: (1) increasing, where the first weight was lighter than the reference weight and progressively increased in 20g steps, (2) decreasing, where trials started with a heavier weight and progressively decreased. We calculated the discrimination threshold (DT) across sequences as the weight for which the subject's response changed sign. The difference between the higher and the lower threshold was defined as "uncertain area". We predicted that controls should overestimate the reference weight lifted by their non-dominant hand because the same effort produces more force when applied to stronger muscles. If the basal ganglia mediates sensation of effort, patients' capability to discriminate weights should be degraded. As expected, normal subjects overestimated the reference weight lifted by their non-dominant index and showed a restricted uncertain area, thus, indicating that were able to discriminate minimal differences in generated forces. By contrast, patients with HD underestimated the reference weight lifted by their non-dominant hand and showed a broad uncertain area, thus, demonstrating that they could detect only important differences in the matched efforts. These results suggest that effort sensation critically involves the basal ganglia. In normal conditions, in parallel with the efferent command of force, an efferent copy reflecting the magnitude of the voluntary motor command is transmitted to sensory centres. This signal and/or the integration of sensory feedback which generates what is experienced as the sense of effort, would be altered in HD.

Adult↗
PubMed1998

Basolateral amygdala lesions block the disruptive effects of long-term adrenalectomy on spatial memory.

The present study examined, in rats with N-methyl-D-aspartate-induced lesions of the basolateral amygdala, the effects of long-term adrenalectomy (i.e. 12-13 weeks) on memory for spatial and cued learning in a water maze. In sham amygdala-lesioned rats, adrenalectomy induced impairments in acquisition and retention performance for the spatial, but not the cued water-maze task. The adrenalectomized rats sustained selective degeneration and death of granule cells in the dentate gyrus dorsal blade. Continuous supplementation of the animals' drinking water with an extremely low dose of corticosterone (20 microg/ml) did not block the retention deficit, but blocked the acquisition deficit and the dentate gyrus neurodegenerative changes. The finding that the memory impairments and dentate gyrus neurodegeneration are dissociable supports the view that the adrenalectomy-induced memory effects are due to the loss of activational effects of circulating adrenal hormones at the time of learning. In adrenalectomized rats which received corticosterone as well as those which did not, lesions of the basolateral amygdala blocked the impairing effects of adrenalectomy on spatial learning and memory. However, the basolateral amygdala lesions did not affect the neurodegenerative changes in the dentate gyrus. In conclusion, the present findings provide further evidence that the basolateral amygdala is involved in regulating stress hormone effects on learning and memory.

Adrenalectomy↗
PubMedDate not supplied

Development of spatial navigation following prenatal cocaine and malnutrition in rats: lack of additive effects.

The effects of prenatal cocaine exposure and protein malnutrition on the development of spatial navigation were assessed in rats. Sprague-Dawley dams were fed a low-protein (6% casein), adequate protein (25% casein), or a laboratory chow diet prior to mating and throughout pregnancy. Within each diet group, rats received either cocaine injections (30 mg/kg i.p. two times per week prior to mating and then 30 mg/kg s.c. daily from day 3 to 18 of pregnancy) or saline injections. All litters were fostered on the day of birth to saline-injected mothers fed either the 25% casein diet or the chow diet. Gestation length was decreased by prenatal cocaine exposure whereas litter size was reduced by prenatal malnutrition. On postnatal days 21, 25, 30, or 70, rats were tested for their ability to locate a submerged platform in a Morris water maze. In well-nourished rats, prenatal cocaine increased the mean distance swum during acquisition over days 21-30, a difference that was abolished in rats with prenatal malnutrition. In the absence of drug exposure (saline groups), prenatal malnutrition was itself associated with longer swim paths. Neither prenatal insult affected the accuracy of the spatial navigation at these ages, as determined by their search pattern when the platform was removed. On postnatal day 25, rats raised on the chow diet exhibited superior performance to that of rats raised on the 25% casein diet, but by day 30 these two well-nourished groups were comparable. At day 70, prenatal cocaine impaired spatial performance on the first session, in well-nourished rats only. Thus, these results provide no support for the hypothesis that prenatal cocaine and protein malnutrition combine to produce a greater effect on behavioral development than either insult alone.

Animals↗
PubMed2003

Preventing sexually transmitted infections and unintended pregnancy, and safeguarding fertility: triple protection needs of young women.

The problems and risks of unprotected sex, unintended pregnancy and sexually transmitted infections are inextricably linked. In this context, the critical yet overlooked problem of infertility also needs to be addressed. Dual protection means concurrent protection against unintended pregnancy and STI/HIV. This paper argues for a more comprehensive notion of "triple protection" to include the safeguarding of fertility. This is intended explicitly to draw out the connection between infertility and STIs--using the "visibility" of fertility and infertility and people's immediate connection with them--and in so doing to bolster STI prevention and control efforts. It could also serve to highlight the connections between infertility and unsafe abortion and delivery practices, which still exist in many developing countries. Understanding differences in perception and weighting of protection concerns by young women and men, whether they wish to start, postpone or avoid pregnancy, is essential for the creation of effective programmes. Building on efforts to promote dual protection, a strategic opportunity exists to include prevention of infertility into safer sex messages and to address the fragmentation of reproductive health and HIV/AIDS programmes.

Attitude to Health↗
PubMed2003

Cigarette smoking for weight loss or control among adolescents: gender and racial/ethnic differences.

PURPOSE: To describe gender and racial/ethnic differences in the prevalence of cigarette smoking for weight loss or control in an adolescent population-based sample, and relationships among heavy smoking, weight concerns and smoking to lose or control weight. METHODS: Anonymous questionnaires were administered to 81,247 9th and 12th grade public school students across the state of Minnesota in 1998. Variables of interest included smoking frequency, weight concerns, and smoking for weight loss or control. Logistic regression analyses were used to estimate the odds of smoking to lose or control weight by race/ethnicity and gender, and to evaluate the relationships between smoking to lose or control weight and heavy smoking, perceptions of overweight, and weight concerns by race/ethnicity and gender. RESULTS: With the exception of black females, female smokers of different racial/ethnic groups were as likely as white girls to smoke for weight loss or control. Compared to white male smokers, American Indian and Asian American male smokers were more likely to smoke for weight loss or control, and black, Hispanic, and mixed race male smokers were equally likely to smoke for weight loss or control. Heavy smokers, smokers who perceived themselves as overweight or were weight-concerned were significantly more likely to report smoking as a weight control method. CONCLUSIONS: Smoking for weight control is prevalent across many race/ethnic groups and both genders among adolescents.

Adolescent↗
PubMed1984

Weight of evidence supports one operation for "ratios" and "differences" of heaviness.

This paper investigates an apparent contradiction between recent studies of "ratios" and "differences" of heaviness. Birnbaum and Veit (1974) found a single rank order for judgments in the two tasks, whereas Rule, Curtis, and Mullin (1981), who used a different stimulus set, procedure, and experimental design, reported two orders. To investigate the cause of this discrepancy, the present study manipulated the experimental design using the same stimuli and procedure as Rule et al. (1981). In one experiment (within-subject designs), each subject judged all combinations of the standard and comparison stimulus; in the other experiment (between-subjects designs) each subject received only one standard, and different groups of subjects were given different standards. "Ratios" and "differences" of heaviness were monotonically related for the majority of subjects who judged all combinations of standards and comparisons. Variations in the modulus and response examples did not affect the rank order of "ratios" within subjects. These results suggest that the contradiction in results is due to the difference in experimental design rather than differences in stimuli or procedure. In the between-subjects designs, the rank order of the "ratio" judgments depended on the standards and examples. Both previous and present results are consistent with the theory that subjects use one operation, subtraction, for both tasks and that the judgment function varies with between-subjects manipulations of the standard, examples, and modulus.

Humans↗
PubMed2000

Sensation weighting in comparison and discrimination of heaviness.

Participants lifted pairs of successively presented weights and compared them for heaviness, using the constant method with 2, 3, or 6 judgment categories. The standard weight (St) was 100, 200, or 300 g, either roving or fixed within a block. For each St, there were 5 comparison (Co) weights. The lifting orders were St-Co and, with 6 categories, Co-St. Time-order errors were negatively related to St magnitude, particularly with roving St. In terms of Hellström's sensation-weighting theory, this result was accounted for by a smaller weighting coefficient for the first-presented stimulus than for the second. Time-order errors were negative on average, which was explained as the result of this weighting in conjunction with a low position of the reference level because of light background heaviness. With roving St, the dispersion of the subjective intrapair difference increased with St magnitude, providing evidence for Ekman's law (G. Ekman, 1956, 1959).

Adult↗
PubMed2001

Visual localization of the center of mass of compact, asymmetric, two-dimensional shapes.

This study aimed at understanding how visual information is used to locate the center of mass. The center of mass is an important physical property of objects that must be taken into account when grasping and/or manipulating them. Participants were instructed to identify the point of equilibrium of compact, bidimensional, massless shapes displayed on a touch screen. The point of equilibrium was defined as the point on the face of the object that would allow one to balance the object in the horizontal position. Seven different triangles and 18 different quadrilaterals in different orientations were used as stimuli. It was found that participants can accurately and consistently estimate the position of the center of mass. The small observed errors were systematically influenced by the shape of the object. The participants tended to locate the center of mass at the center of an inscribed circle instead of the true center of mass. In general, the shape effect was impervious to the orientation of the figure and to the mode of response (left hand, right hand, or mouse).

Adult↗
PubMed1981

Subjective ratios and differences in perceived heaviness.

In previous studies, judgments of ratios and differences in subjective magnitude have yielded similar orders, consistent with a hypothesis that a single perceived relation underlies both judgment tasks. In the present research, 15 subjects estimated heaviness differences between 28 pairs of eight weights and each of 8 groups of 10 subjects evaluated heaviness ratios of eight variable stimuli with respect to a different standard stimulus. Presenting stimuli that were equally spaced on a cube-root scale of weight enhanced expected ordinal discrepancies between ratio and difference estimates, and employing independent groups for each standard stimulus in ratio estimation eliminated a possible bias due to varying standards within the presentation sequence. Differences in orders of ratio and difference estimates together with differences in scales obtained from non-metric analyses in terms of a difference model indicated that the judgments were based on two perceived relations that are ordinally consistent with arithmetic operations of ratios and differences. A ratio scale of heaviness was derived from the combined orders of subjective ratios and differences.

Discrimination Learning↗
PubMed1989

Performance of a weight-lifting task by normal and deafferented monkeys.

The role of topographic information from a moving limb in controlling the trajectory of the limb was explored by comparing the ability of 3 normal and 2 unilaterally deafferented monkeys to generate criterion elbow flexions when opposed by different weights. When lifting initially unknown weights, both groups of monkeys reached maximum positions that were inversely related to load. The performance of the deafferented monkeys approached that of the normal monkeys on these first lifts of initially unknown weights. The preceding load had a greater effect on the initial lifts of the deafferented monkeys than on those of the normal monkeys. When allowed to repeatedly lift the same weight, both groups obtained a high density of reinforcement, but the responses of the deafferented monkeys were more dependent on the weight. The results are consistent with the hypothesis that the mechanical properties of muscle make an important contribution to compensation.

Afferent Pathways↗
PubMed2005

Somatosensory processing and schizophrenia liability: proprioception, exteroceptive sensitivity, and graphesthesia performance in the biological relatives of schizophrenia patients.

In the present study, the authors examined somatosensory processing in 30 biological relatives of persons with schizophrenia (hereafter called "schizophrenia relatives"), 30 biological relatives of persons with bipolar affective disorder (psychiatric family control subjects), and 30 healthy control subjects with no family history of psychopathology. All 3 groups completed a weight discrimination task, a 2-point discrimination task, and a complex cognitive somatosensory task (i.e., graphesthesia). The schizophrenia relatives performed significantly worse on all 3 somatosensory tasks compared with both the healthy control subjects and the bipolar relatives. The healthy control subjects and psychiatric family control subjects showed no significant differences on any of the somatosensory tasks. Within the weight discrimination and 2-point discrimination tasks, schizophrenia relatives showed group differences on the d' index, the measure of sensitivity, whereas all 3 groups did not differ on lnbeta, the measure of response bias, suggesting a genuine difference in weight and touch sensitivity. The d' value of the weight discrimination task was significantly associated with both the cognitive-perceptual factor and negative symptom factor of the clinical questionnaire (e.g., Schizotypal Personality Questionnaire; SPQ), whereas the 2-point discrimination d' value and graphesthesia scores were significantly associated only with the cognitive-perceptual factor of the SPQ. Implications for the possible relation between somatosensory task performance and schizophrenia liability are discussed.

Adolescent↗