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PubMed1991

Mass discrimination under Gz acceleration.

The purpose of this study was to assess how the perception of mass discrimination is affected by elevated Gz acceleration. Previous experiments studied mass discrimination under weightless conditions. Ten subjects were tested with the Dynamic Environment Simulator (DES) at Wright-Patterson Air Force Base. Masses of 105, 110, 115, 120, and 125 g were compared to a 100-g standard for delta Ms of 5, 10, 15, 20, and 25 g. The subject had to choose which mass felt heavier. This was done at 1, 2, and 4 Gz. Significant differences were found between each of the G levels, and the subjects made more errors at higher Gz. Significant differences were also found between each of the delta Ms, except between delta Ms of 20 and 25 g. Using regression lines, the difference limen was calculated at the 75% correct response level for each Gz. The Weber fraction was found by dividing the difference limen by the 100-g standard. Weber fraction of 0.085, 0.116, and 0.145 were found at 1, 2, and 4 Gz, respectively. Impairment to discrimination was shown by calculating the ratio of the Weber fraction of the elevated Gz to 1 Gz. This demonstrated an impairment to mass discrimination at 1.36 at 2 Gz and 1.71 at 4 Gz. Impairment of mass discrimination under elevated G indicates that loss of adaptation is more important than weight or mass constancy or any other factors which would increase gravitational sensory cues. This study attempted to show adaptation by comparing runs done on different days. To show aftereffect, intervals of 1 G were compared to each other. The study did not find any adaptation or aftereffect. When compared to previous studies done in weightlessness, microgravity was found to be more detrimental to mass discrimination than macrogravity, at least up to 4 Gz.

Acceleration↗
PubMed2001

Body mass index, menarche, and perception of dieting among peripubertal adolescent females.

OBJECTIVE: To examine perceptions of dieting among pre and postmenarchial female school students. METHOD: All 51 female students of mean (SD) age 12.6 (0.6) years from a state school volunteered to complete a questionnaire about general health, eating and weight control behaviors, and menstrual status. Height and weight were measured. Focus groups using structured questions and discussion were used to elicit responses about the meaning of dieting and its association with menarche. RESULTS: Postmenarchial females were significantly more likely than the same age premenarchial students to have increased their body mass index (BMI), to clearly articulate the meaning of dieting, to report trying to lose weight, and to use diet and exercise to lose weight. Premenarchial females did not have a clear perception of dieting. Premenarchial females who reported trying to lose weight equated dieting with healthy eating and did not include losing weight or the behaviors and feeling associated with the concept of dieting unless their BMI had increased and menarche was imminent. DISCUSSION: The concept of dieting that may result in weight loss and the behaviors and feelings associated with dieting did not develop until menarche and is likely to be associated with the rapid increase in height, weight, and body fat that precedes menarche. Educational interventions aimed at preventing eating disorders among premenarchial adolescents may therefore be inappropriate, ineffective, and potentially dangerous.

Adolescent↗
PubMed1999

Wellness profile of midlife women with a chronic illness.

Among issues important to women's health are their wellness profiles including indicators such as activity level, weight status, breakfast and snacking patterns, health status perceptions, and alcohol and tobacco use. This is particularly true for midlife women with a long-term illness. The purpose of this study is to identify the wellness profile of a group of midlife women with multiple sclerosis (MS), and to compare their life-style indicators with national health statistics. Overall, the women in the study group indicated a lower perception of their health status and were less active. However, the women in this study group demonstrated healthier body weights, used less tobacco and alcohol, had better breakfast patterns, and comparable snacking patterns, indicating that may be more attuned to their bodies than women without chronic illnesses. Identifying women's wellness profiles can assist practitioners in addressing the issues of health for women managing a long-term illness.

Activities of Daily Living↗
PubMed2003

The impact of the Pathways intervention on psychosocial variables related to diet and physical activity in American Indian schoolchildren.

BACKGROUND: The purpose of this study was to examine the impact of the Pathways intervention on pychosocial variables related to physical activity and diet in American Indian children. METHODS: Schools serving American Indian children were randomized to a multicomponent intervention or control condition. At baseline (fall of third grade) and in the spring semester of third, fourth, and fifth grades 755 boys and 692 girls completed a classroom-administered questionnaire. The questionnaire assessed self-efficacy, knowledge, and behavioral intentions related to diet and physical activity, as well as weight loss behaviors and body image. RESULTS: Knowledge of nutrition and physical activity messages increased in both boys and girls in the intervention group compared to controls; however, knowledge of which foods contained more fat did not increase consistently. Compared to controls, self-efficacy to be physically active increased among girls in intervention schools, but not among boys, whereas self-efficacy to make more healthy food choices did not increase more than in controls in either gender. In the intervention group, compared to controls, healthy food intentions and participation in physically active behaviors increased in both boys and girls. Perception of healthy body size and weight loss attempts did not differ in the intervention and control groups. CONCLUSION: The Pathways intervention program had a positive impact on several aspects of obesity-related knowledge, attitudes, and behaviors.

Child↗
PubMed2001

Body dissatisfaction among White and African American male and female college students.

Body size perception has been shown to be highly influenced by cultural factors including race. This study assessed body size perceptions of a convenience sample of college students (N=630). Included in a paper-and-pencil survey were current height and weight (body mass index (BMI)=wt [kg]/ht(2) [m]), perceived BMI, desired MI and perceptions of BMIs desired by others. Also assessed were perceptions of underweight, acceptable weight and overweight/obesity. African American females were found to have a higher current BMI than Whites (P< or =.001), higher desired BMI (P< or =.001) and higher BMI perceived to be desired by others (P< or =.001). African American and White males did not differ on any of these measures. Most (83%) underweight (BMI<19) African American females perceived themselves as underweight while only about one-half of underweight (56%) White females perceived themselves as underweight. Almost half (43%) of White females and about a fourth (27%) of African American females of acceptable BMI range (BMI=19-25) desired to be in the underweight range. Of those who were overweight (BMI=25-30), 20% of the Whites and only 3.0% of the African Americans chose an underweight silhouette as being desired. While African Americans and White males tended to have similar perceptions that there remains sociocultural influences in African American females regarding acceptance of a large body size.

Journal Article↗
PubMed1998

International consensus recommendations. Summary statement and additional suggested guidelines. European Consensus Conference, November 1991. American College of Chest Physicians consensus statement of 1995. International Consensus Statement, 1997.

Since the NIH Consensus Conference in 1986, the developments in the field of prevention and treatment of venous thromboembolism were mainly characterized by a more specific and extended use of new prophylactic agents such as low-molecular-weight heparins as well as the perception that out-patients may be at risk for thromboembolic complications, too. Therefore, in 1991 and 1995, consensus conferences were held in Europe and North America in order to analyze the risk constellation of various patient populations and to give recommendations for primary prophylaxis and treatment of thromboembolic complications. The most recent, the 1997 International Consensus Recommendations are also discussed.

Anticoagulants↗
PubMed1999

Why should obesity be managed? The obese individual's perspective.

Weight loss can be achieved using a variety of different methods, alone or in combination, including energy restricted diets, drug treatment and surgical intervention. The difficulty is maintaining weight loss over a prolonged period. Physicians, dietitians and nurses are often pessimistic about their ability to manage obesity. Such negative attitudes, combined with the erroneous belief that obesity is not a serious medical condition, have adversely affected the level of care received by obese patients. Despite this, the family doctor is often approached for help with weight control. Obese patients are generally well informed about diet and weight issues, and are in a good position to critically assess the weight loss advice given by their doctor. The perception of such advice formed part of a questionnaire completed by obese people (346 female/24 male) who successfully reduced their weight while attending a weight loss group. Eighty per cent had previously been advised by their doctor to lose weight, but guidance on how to do this was generally judged to be poor. Only 22% of subjects received positive advice, although 23% of subjects reported that their doctor's advice was indirectly responsible for their weight loss. Patients derived evident health benefits from their weight loss and were generally given a positive response on returning to their doctor. To help patients lose weight, doctors must realise that obesity is a serious chronic medical condition. Ongoing help and support from doctors and other healthcare professionals is a key element in successful long-term weight management.

Attitude of Health Personnel↗
PubMed1998

Neuropsychological consequences of extreme weight loss and dietary restriction in patients with anorexia nervosa.

This study examined the effects of weight loss and nutritional status on the cognitive performance of patients with anorexia nervosa. The intellectual, memory, attentional, verbal fluency and visuospatial abilities of 34 females with anorexia were compared to that of 31 normal weight-for-height females. Group differences in anxiety and depression were found but neither variable was related to the cognitive performance of patients with anorexia. Moreover, nutritional status and weight loss bore little relationship to the cognitive scores of the patient group. Overall, patients with anorexia were found to be deficient in their ability to recall meaningful prose and visuospatial information. The failure to find many cognitive deficits in this sample may reflect the fact that few patients with anorexia exhibited frank nutritional deficiencies.

Adult↗
PubMed2001

Motion capture depends on signal strength.

When flickering dots are superimposed onto a drifting grating, the dots appear to move coherently with the grating. In this study we examine: (i) how the perceived direction of a compound stimulus composed of superimposed grating and dots, moving in opposite directions with equal speeds, is influenced by the relative strength of the motion signals; (ii) how the perceived speed of a compound stimulus composed of superimposed grating and dots, moving in the same direction but at different speeds, is influenced by the relative strength of the motion signals; and (iii) whether this stimulus is discriminable from its metameric speed match. Dot signal strength was manipulated by using different proportions of signal dots in noise and different dot lifetimes. Both the perceived direction and speed of these compound stimuli depended upon the relative motion-signal strengths of the grating and the dots. Those compound stimuli that appeared coherent were not discriminable from the speed-matched metameric compound stimuli. When the signals were completely integrated into a coherent compound stimulus, the local motion signals were no longer perceptually available, though both contributed to the global percept. These data strongly support a weighted-combination model where the relative weights depend on signal strength, instead of a winner-takes-all model.

Humans↗
PubMed1997

Effects of communication, information overlap, and behavioral consistency on consensus in social perception.

Three experiments (N = 69, 162, and 201, respectively) were conducted to test the mathematically derived predictions of the Weighted Average Model (D. A. Kenny, 1991) of consensus in interpersonal perception. Study 1 estimated the effect of perceiver communication. Study 2 estimated the effects of communication and stimulus overlap, and Study 3 estimated the effects of communication, overlap, and target consistency on consensus. The strongest consensus was found when perceivers communicated about highly overlapping information about targets who were cross-situationally consistent. Conversely, the lowest level of consensus was observed when perceivers did not communicate and had nonoverlapping information about targets who were cross-situationally inconsistent. Both stimulus variables (overlap and consistency) and an interpersonal variable (communication) affected consensus as predicted by the Weighted Average Model.

Adolescent↗
PubMed1992

The overview effect: the impact of space exploration on the evolution of nursing science.

The purpose of this article is to explore the overview effect, an experience evoked by space travel that has the capacity to transform all patterns of human existence and evolution toward greater potentials in human diversity and creativity. As nurses migrate with humanity into the solar system and beyond, they will experience the overview effect. The core components of the effect include changed perceptions of space, time, sound, and weight which have the potential to transform the evolution of nursing science. Nursing paradigms will encompass a view of humanity as integral with an infinite evolutionary universe. After generations of living in space in a diversity of new environments, the physical body will undergo radical changes, and the meaning of health will be transformed. The article concludes with a discussion on the parallels between Rogers' science of unitary human beings and the overview effect.

Forecasting↗
PubMed1995

Development of the perceptions of racism scale.

Racism may be a factor in low-birth-weight (LBW) and preterm delivery in African American childbearing women. Because no satisfactory measure of racism existed, the Perception of Racism Scale (PRS) was developed. The PRS was pilot tested on 109 participants from churches and community organizations. The scale was then used in a study of 136 childbearing women to investigate LBW and preterm delivery. Twenty items rated on a 4-point Likert-type scale were scored with 1 as the lowest and 4 as the highest perception of racism. Alpha reliabilities were .88 for the pilot and .91 for the study. Content validity was strengthened by expert panel critique. Reliability, content validity, and construct validity were demonstrated and no undue participant burden was observed. The scale is an effective instrument to measure perceptions of racism by African American women.

Adolescent↗
PubMed2005

Where does your own action influence your perception of another person's action in the brain?

Activation of premotor cortex during the observation and imitation of human actions is now increasingly accepted, but it remains unclear how the CNS is able to resolve potential conflicts between the observation of another person's action and the ongoing control of one's own action. Recent data suggest that this overlap leads to a systematic bias, where lifting a box influences participant's perceptual judgments of the weight of a box lifted by another person. We now investigate the neural basis of this bias effect using fMRI. Seventeen participants performed a perceptual weight judgment task or two control conditions while lifting a light box, a heavy box or no box during scanning. Brain regions related to perceptual bias were localized by correlating individual differences in bias with BOLD signal. Five regions were found to show correlations with psychophysical bias: left inferior frontal gyrus, left central sulcus, left extrastriate body area, left lingual gyrus and right intraparietal sulcus. The cluster in primary motor cortex was also activated by box lifting, and the cluster in extrastriate body area by the observation of hand actions and the weight judgment task. We suggest that these brain areas are part of a network where motor processing modulates perceptual judgment of observed human actions, and thus visual and motor processes cannot be thought of as two distinct systems, but instead interact at many levels.

Adolescent↗
PubMed1994

A Perceived Health Index for use in persons with advanced HIV disease: derivation, reliability, and validity.

Acceptance of health status as an outcome in clinical trials of new treatments for HIV disease has been hampered by the lack of valid and clinically relevant means of summarizing differences across multiple dimensions. We formed a summary Perceived Health Index from health status measures adapted from RAND Medical Outcomes Study scale and contained in the HIV-PARSE survey instrument, which had been administered to a large number of participants in clinical trials for advanced HIV disease. The psychometric properties of the included health status scales were assessed using multitrait scaling and test-retest stability. Weights for the index were derived from regressions of Current Health Perceptions on the domain-specific health status scales. The effect of participant characteristics on weights was tested. Finally, the reliability and known-clinical groups validity of the index was assessed. Data were obtained from 1,862 clinical trial participants who provided a total of 7,352 observations. The mean CD4 count was 131. The internal consistency reliability of the multi-item scales ranged from 0.86 to 0.90, and items demonstrated excellent discrimination across scales. The domain-specific scales explained 59% of the variation in the Current Health Perceptions scale (P < 0.00001). The resulting Perceived Health Index was equal to 0.20 Physical Functioning + 0.15 Pain + 0.41 Energy/Fatigue + 0.10 Emotional Well-being + 0.05 Social Functioning + 0.09 Role Functioning. The strong positive bivariate relationship between the Cognitive Function/Distress scale and the Current Health Perceptions scale was subsumed by the combination of the other domain-specific scales in multiple regressions, so it does not appear independently in the index. The proportional weights used in the index were insensitive to variations in demographics. The reliability of the index was conservatively estimated to be 0.94. Patients with index scores in the lowest quartile had a 2- to 11-fold higher probability than those in the highest quartile of reporting various specific clinical events, and the index correlated significantly more highly with the number of such events than did the current health perceptions scale. The modified MOS health status scales included in the HIV-PARSE are reliable and valid in patients with advanced HIV disease. The Perceived Health Index provides a reliable and valid means of summarizing self-reported current health, correlates strongly with clinical indicators, and should be useful as a outcome measure in patients enrolling into clinical trials of therapies for advanced HIV disease. Regression based weights are a useful means of summarizing multidimensional measures.

Adolescent↗
PubMed1998

Body-size estimation by obese subjects.

The present aim was to explore the body-image perception of a group of 60 hospitalized obese subjects, aged between 25 and 50 years, undergoing a weight loss treatment and 60 normal-weight persons. The 1978 modified version of the Askevold perception test by Allamani, Marasco, Michele, and Morandi was given. This nonverbal test is aimed at evaluating subjects' perception of the dimensions of different parts of the body by exploiting their projection into space. Each body area (head, the thoracic area, the abdominal area, and the pelvic area) perceived by a subject was calculated using a specifically designed software program (AREA.BASIC2); the same program was used to calculate actual body area. After obtaining the percentage deviation index for each individual [(perceived area/real area) x 100], mean values were analyzed. Obese subjects significantly underestimated the four body areas, unlike the normal weight subject who largely overestimated the abdominal and pelvic areas.

Adult↗
PubMed2001

Dieting behavior in Norwegian adolescents.

In a sample of Norwegian adolescents (n = 1117) 27, 4% of the girls and 9% of the boys reported that they were dieting. Using multiple regression analyses, we were able to predict 50% of girls dieting behavior and 24% of boys dieting behavior. Psychological concerns relating to weight and eating (WEC) as well as perceptions of feeling fatter than others were the only significant predictors of dieting in girls, whilst dieting in boys could also be predicted by their Body Mass Index. Dieting girls who scored high on the Weight and Eating Concerns Inventory were found to suffer constipation and binge eating attacks more often than other dieting girls. This was taken as an indication that these girls were at risk of developing an eating disorder.

Adolescent↗
PubMed1988

Haptically perceiving the distances reachable with hand-held objects.

Nine experiments are reported on the ability of people to perceive the distances reachable with hand-held rods that they could wield by movements about the wrist but not see. An observed linear relation between perceived and actual reaching distances with the rods held at one end was found to be unaffected by the density of the rods, the direction relative to the body in which they were wielded, and the frequency at which they were wielded. Manipulating (a) the position of an attached weight on an otherwise uniformly dense rod and (b) where a rod was grasped revealed that perceived reaching distance was governed by the principal moment(s) of inertia (I) of the hand-rod system about the axis of rotation. This dependency on moment of inertia (I) was found to hold even when the reaching distance was limited to the length of rod extending beyond an intermediate grasp. An account is given of the haptic subsystem (hand-muscles-joints-nerves) as a smart perceptual instrument in the Runeson (1977) sense, characterizable by an operator equation in which one operator functionally diagonalizes the inertia and strain tensors. Attunement to the invariants of the inertia tensor over major physical transformations may be the defining property of the haptic subsystem. This property is discussed from the Gibsonian (ecological) perspectives of information as invariants over transformations and of intentions as extraordinary constraints on natural law.

Adult↗