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Results for “Weight Perception”

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At least 19 recordsLinked to original sources
PubMed1979

Effect of thumb anaesthesia on weight perception, muscle activity and the stretch reflex in man.

1. We have confirmed the results of Gandevia & McCloskey (1977) on the effect of thumb anaesthesia on perception of weights lifted by the thumb. Weights lifted by flexion feel heavier and weights lifted by extension feel lighter. 2. The change in size of the long-latency stretch reflex in flexor pollicis longus or extensor pollicis longus after thumb anaesthesia cannot explain the effect on weight perception by removal or augmentation of the background servo assistance to muscular contraction. 3. During smooth thumb flexion, thumb anaesthesia increases e.m.g. activity in flexor pollicis longus and extensor pollicis longus for any given opposing torque. 4. During smooth thumb extension the opposite occurs: e.m.g. activity in both extensor and flexor pollicis longus decreases. 5. Clamping the thumb at the proximal phalanx to limit movement solely to the interphalangeal joint reduces or abolishes the effect of anaesthesia on both weight perception and e.m.g. activity during both flexion or extension tasks. 6. Gandevia & McCloskey's findings on the distorting effects of thumb anaesthesia on weight perception cannot be used to support the hypothesis of an efferent monitoring system of the sense of effort. Our results emphasize the close functional relationship between cutaneous and joint afferent information and motor control.

Anesthesia, Local↗
PubMed1991

Body-weight perceptions and selected weight-management goals and practices of high school students--United States, 1990.

Among adults, overweight is associated with elevated serum cholesterol levels, elevated blood pressure, and noninsulin-dependent diabetes and is an independent risk factor for coronary heart disease. Youth who are overweight and remain overweight as adults may increase their risk for certain chronic diseases in adulthood. However, overemphasis on thinness during adolescence may contribute to potentially harmful weight-management practices and eating disorders such as anorexia nervosa and bulimia nervosa. This report presents self-reported body-weight perceptions and selected weight-management goals and practices among high school students in the United States.

Adolescent↗
PubMed1991

Self-reported eating disorders of black, low-income adolescents: behavior, body weight perceptions, and methods of dieting.

This study identified black, low-income adolescents who thought they had anorexia nervosa or bulimia nervosa, identified behaviors common to those who thought they had the disorders, and compared their actual and perceived body weight as well as methods of dieting. Of the 1,930 students in grades 7-12 who participated, about 12% thought they might have an eating disorder. These students also reported having food-related behaviors similar to individuals with eating disorders and which differed significantly from those reported by their peers. Gender was more likely to affect food behavior than age. Though most students were within their expected weight range, those with self-reported eating disorders perceived themselves to be heavier more often than their peers and when their actual weights were compared, they were more likely to weigh more. Of those who had dieted to lose weight, fasting was the most frequently reported restrictive method used.

Adolescent↗
PubMed1990

Weight and perceptions of body image in women and men in a Sydney sample.

Using a modification of the distorting camera technique, 50 obese women (body mass index (BMI; kg/m2 35.1 +/- 1.1), 40 obese men (BMI 38.2 +/- 1.5) and their respective normal weight controls estimated their body size. The obese women, control women and obese men overestimated their body size, whilst control weight men were accurate. The control men were satisfied with their body size, control women less so and the obese were unsatisfied. Whilst the control women considered themselves overweight (BMI 26.7 +/- 0.8 compared to actual BMI 23.1 +/- 0.5, P less than 0.001) their preferred and actual body sizes were identical. There were no differences between obese subjects and controls in the sizes they considered healthy and attractive. The accepted normal size range for a woman was lower than that accepted for men. Older men (both obese and normal weight) accepted larger sizes for women than younger men. These results show that the obese overestimated their body size and supports the notion that there is social pressure on women to strive towards a slimmer ideal, whilst overweight men are more accepted.

Adult↗
PubMed1991

Perceptions of weight and attitudes toward eating in early adolescent girls.

Sixth grade girls (n = 206) responded to questions about their weight, body image, dieting practices, and attitudes toward weight and eating. Results suggested that feeling too fat and wishing to lose weight were becoming normative for young adolescent girls in that the majority of girls wished to weigh less and said that they dieted at least occasionally. For most girls, weight concerns had emerged between the ages of 9 to 11. A sizeable proportion of girls seemed to have adopted a "dieting mentality," claiming to be avoiding fat, counting calories, thinking excessively about food, feeling guilty after eating and overeating, and exercising to lose weight. Such practices were common even among girls who did not describe themselves as overweight or who were satisfied with their appearance. The emergence of these attitudes and behaviors at increasingly younger ages is of grave concern, as several of them are risk factors for the development of serious eating disorders.

Attitude to Health↗
PubMed1992

Adolescents' perceptions of relative weight and self-reported weight loss activities.

Data from the 1990 North Carolina Youth Risk Behavior Survey (YRBS) were used to examine adolescents' perceptions of relative weight and the relationship of these perceptions to physical activity levels, efforts to lose weight, and time spent viewing television. A total of 3,437 ninth and 12th grade respondents to the May 1990 survey were included in the analysis. Of this sample, 25% perceived themselves as "too fat." Of that group, 68% were trying to lose weight. Females made up 75% of those reporting they were "too fat" and were trying to lose weight. White females were more likely to think of themselves as overweight and were more likely to be trying to lose weight than black females. Adolescents who perceived themselves as "too fat" reported fewer days of strenuous activity, fewer hours of strenuous exercise in physical education classes, and more hours spent viewing television on school days.

Adolescent↗
PubMed1979

Quantitative protein changes in the hypothalamic neurons of pubertal male rats, castrated neonatally.

The effect of neonatal castration of male rats on the sexual differentiation of the hypothalamus at puberty was studied. Male rats were castrated on days 1, 5 and 7 after birth. Their brains were processed for study on days 83-85. The neurons and cell nuclei of the preoptic area, mediobasal and ventromedial nuclei were assessed for changes in cell and nuclear sizes and dry weight (calculated using interferometric methods). Neonatal castration resulted in size as well as dry weight increase in the neurons of the anterior and mediobasal hypothalamus. The dry weight increased by 34% (P less than 0.001) in the medial preoptic area, by 25% (P less than 0.001) in the arcuate neurons and by 22% (P less than 0.001) in the ventromedial nucleus. The cell nuclei exhibited perceptible weight increase too--in the medial preoptic area 68% (P less than 0.001); 55% in the arcuate neurons (P less than 0.001), and 39% in the ventromedial region. The weight and size increases in neonatally castrated males were equal to those of females of the same age. In rats castrated on day 7, the cell sizes and dry weights of the ventromedial nucleus increased but the cell nuclei exhibited only little change. It is assumed that the changes in the dry weight may be the result of increased synthetic processes in these groups of neurons which are connected with the tonic and cyclic release of gonadotropins. These changes also point to the hypothalamic differentiation shifting to the female type in the absence of the inducing effect of androgens.

Animals↗
PubMed2025

Differential gene expression study in whole blood identifies candidate genes for psychosis in African American individuals.

Genome-wide association has identified regions of the genome that mediate risk for psychosis. It is possible that variants in these regions confer risk by altering gene expression. This work has predominantly been conducted in individuals of European descent and has focused narrowly on schizophrenia rather than psychosis as a syndrome. In the present study we investigated alterations in gene expression in African American individuals with a range of psychotic diagnoses to increase understanding of the etiology in an underserved population. We performed RNA-seq in whole bloody to survey the transcriptome in 126 patients with a psychosis-spectrum disorder and 217 healthy controls and applied differential gene expression analyses across the genome while controlling for age, sex, population stratification and batch. We found 18 differentially expressed genes (DEGs), some of the locations of the corresponding genes overlap with previously implicated regions for psychosis, but many of which were novel associations. Enrichment analysis of nominally significant genes (p&#xa0;<&#xa0;0.05) revealed overrepresentation of biological processes relating to platelet, immune and cellular function, and sensory perception. Weighted gene co-expression network analysis, applied to identify modules of co-expressed genes associated with psychosis, revealed 10 modules, one of which was significantly associated with psychosis. This module was significantly enriched for DEGs, and for platelet function. These results support the potential role of immune function in the etiology of psychosis, identify novel candidate gene expression phenotypes that correspond to both established and new genomic regions, in individuals of African American ancestry.

Humans↗
PubMed1992

Temporal patterning in cascade juggling.

A key variable in cascade juggling is the proportion of time that a juggler holds onto a juggled object during a hand cycle, that is, the time from catch to throw in relation to the time from catch to catch. Space-time constraints and principles of frequency locking suggest 3/4 as the primary ratio and 2/3 and 5/8 as the most accessible options. In 5 experiments, object number, mass, and type (ball or scarf) were manipulated together with the frequency at which the objects were juggled. With 5 or 7 balls, the ratio was 3/4, independent of frequency. With 3 balls, the ratio decreased with frequency, with 3/4, 2/3, and 5/8 tending to predominate independently of the force variations induced by variation in object mass. With 3 scarves, ratios varied inversely with frequency and often exceeded 3/4. Implications for a dynamical theory of juggling were discussed with the issue of relative timing in coordination and the manipulation of task constraints as an experimental strategy.

Attention↗
PubMed1975

On the psychophysical law: an information theory interpretation.

For more than a century Fechner's psychophysical law has been the subject of dispute and debate. Fechner based his law on Weber's indisputable observations and measurements. Yet, using these observations as a starting point, but measuring information instead of sensation, one may arrive at numerical laws quite different from Fechner's psychophysical law.

Differential Threshold↗
PubMed1989

Understanding collision dynamics.

In two experiments we investigated people's ability to judge the relative mass of two objects involved in a collision. It was found that judgments of relative mass were made on the basis of two heuristics. Roughly stated, these heuristics were (a) an object that ricochets backward upon impact is less massive than the object that it hit, and (b) faster moving objects are less massive. A heuristic model of judgment is proposed that postulates that different sources of information in any event may have different levels of salience for observers and that heuristic access is controlled by the rank ordering of salience. It was found that observers ranked dissimilarity in mass on the basis of the relative salience of angle and velocity information and not proportionally to the distal mass ratio. This heuristic model was contrasted with the notion that people can veridically extract dynamic properties of motion events when the kinematic data are sufficient for their specification.

Acceleration↗
PubMed1977

Social aspects of body image: perception of normalcy of weight and affect of college undergraduates.

Two aspects of body image, perception of normalcy of weight and affect, were studied by means of a paper-and-pencil test with 62 male and 117 female undergraduates. The relationship of the social characteristics of sex, age, race, and actual body weight (underweight, normal weight, overweight) to body-image distortion was investigated. Individuals who were underweight or overweight were more likely to perceptually distort their weight-related appearance than were normal weight respondents. Among those who misperceived their weight-related appearance, both underweight and overweight persons tended to normalize their appearance. Among those who misperceived their weight-related appearance, sex was also related to the type of perceptual distortion experienced. Females tended to perceive themselves as appearing heavier, whereas males tended to perveive themselves as appearing lighter, than they actually were. There was no relationship between perceptual distortion of body weight and body affect. Age, race, and actual body weight were related to affect. Affect was more negative among young respondents than older respondents. White individuals had poorer affect scores than non-whites. Overweight respondents also had more negative affect scores than other respondents.

Adolescent↗
PubMed1977

Effect of weight and sex on perception of line length.

56 obese and 103 normal-weight college students were asked to make line-length estimations of lines on either a light or dark background. Analysis of the results showed significant interactions between weight and contrast and sex and contrast, with the line estimations by women and normal weight individuals being more dependent on the contrast.

Body Weight↗