Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SIZE 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 1,261 records · Page 70Linked to original sources
PubMed2005

Intergenerational perceptions of body image in hispanics: role of BMI, gender, and acculturation.

OBJECTIVE: To assess role of BMI, gender, and acculturation on maternal and children's perception of body size, body ideal, and attractiveness. RESEARCH METHODS AND PROCEDURES: Eighty mothers and their 6- to- 12-year-old children (41 boys, 39 girls) participated. Maternal and children's perceptions of body size (actual and ideal) and attractiveness were assessed through a pictorial instrument. Mother and child height and weight, demographic, and acculturation characteristics were also assessed. RESULTS: Seventy-nine percent of the mothers were overweight, and 32% of the boys and 34% of the girls were overweight or at-risk for overweight. BMI influenced the children's selection of perceived ideal size. Overweight or at-risk for overweight children were more likely to select thinner figures as the ideal size than non-overweight children. Gender and acculturation differences concerning children's perceptions of body size and attractiveness were also found. Girls perceived the obese figure as being less attractive than did the boys. More acculturated children were likely to select thinner figures as more attractive than their less acculturated counterparts. Maternal acculturation was associated positively with the girls' choice of thinner figures as an ideal body size, but not with the boys. Mothers viewed their daughters' actual body size and BMI as ideal, although 34% of the girls were at-risk for overweight. Mothers perceived average body size figures as more attractive for their sons. DISCUSSION: Findings from this study provide empirical data about the role of BMI, gender, acculturation, and familial influences on children's perceptions of actual and ideal body sizes and attractiveness.

Acculturation↗
PubMed1984

Perceiving affordances: visual guidance of stair climbing.

How do animals visually guide their activities in a cluttered environment? Gibson (1979) proposed that they perceive what environmental objects offer or afford for action. An analysis of affordances in terms of the dynamics of an animal-environment system is presented. Critical points, corresponding to phase transitions in behavior, and optimal points, corresponding to stable, preferred regions of minimum energy expenditure, emerge from variation in the animal-environment fit. It is hypothesized that these points are constants across physically similar systems and that they provide a natural basis for perceptual categories and preferences. In three experiments these hypotheses are examined for the activity of human stair climbing, by varying riser height with respect to leg length. The perceptual category boundary between "climbable" and "unclimbable" stairs is predicted by a biomechanical model, and visually preferred riser height is predicted from measurements of minimum energy expenditure during climbing. It is concluded that perception for the control of action reflects the underlying dynamics of the animal-environment system.

Adult↗
PubMed1992

The discriminability of remembered magnitudes.

Psychometric functions and the associated indices of discriminative performance (i.e., the point of subjective equality [PSE], just noticeable difference, and Weber fraction) were obtained with the method of constant stimuli using perceptual and remembered line-length standards. Three important results were obtained. First, comparisons with a perceptual or a remembered standard were sensitive to variations of absolute stimulus differences with a common ratio; that is, Weber's law was violated. Second, relative to discriminative performance with the longest and shortest remembered standards, comparisons involving mid-range remembered standards displayed increased variability in the PSE and inflated Weber fractions, characteristic of a reduction in the quality of the memorial representation. Finally, large and negative time-order errors (TOE) were observed for successive line judgments but not for those involving remembered standards. The implications of these findings for research concerned with the relationships between perception and memory, as well as the TOE phenomenon, are discussed.

Adult↗
PubMed2006

[The influence of geometric visual illusions on saccadic eye movements].

BACKGROUND: The aim of this study was to investigate whether visually perceived length differences of Mueller-Lyer figures result in amplitude differences of saccadic eye movements along the figures. METHODS: Video recordings of eye movements were obtained from 35 healthy volunteers (aged 18 - 30 years) when scanning the endpoints of Mueller-Lyer targets. RESULTS: Saccades between the ends of lines with inward-pointing arrowheads had significantly greater amplitudes than saccades between the ends of lines with outward-pointing arrowheads. This bias was observed for both horizontal and vertical target orientations, and was maintained with a smaller amplitude, after fixation periods were extended from 1 s to 4 s. CONCLUSIONS: Changes in length perception by visual illusions correspond with changes in the amplitude of saccadic eye movements. Therefore, recordings of saccadic eye movements offer the opportunity to assess changes in visual object perception based on changes of central image processing at the cortical level.

Adolescent↗
PubMed2006

Response times seen as decompression times in Boolean concept use.

This paper reports a study of a multi-agent model of working memory (WM) in the context of Boolean concept learning. The model aims to assess the compressibility of information processed in WM. Concept complexity is described as a function of communication resources (i.e., the number of agents and the structure of communication between agents) required in WM to learn a target concept. This model has been successfully applied in measuring learning times for three-dimensional (3D) concepts (Mathy and Bradmetz in Curr Psychol Cognit 22(1):41-82, 2004). In this previous study, learning time was found to be a function of compression time. To assess the effect of decompression time, this paper presents an extended intra-conceptual study of response times for two- and 3D concepts. Response times are measured in recognition phases. The model explains why the time required to compress a sample of examples into a rule is directly linked to the time to decompress this rule when categorizing examples. Three experiments were conducted with 65, 49, and 84 undergraduate students who were given Boolean concept learning tasks in two and three dimensions (also called rule-based classification tasks). The results corroborate the metric of decompression given by the multi-agent model, especially when the model is parameterized following static serial processing of information. Also, this static serial model better fits the patterns of response times than an exemplar-based model.

Adolescent↗
PubMed1994

[Standardized analysis of visuospatial perception. Studies of objectivity, reliability and validity].

Retest reliability and validity of a computational method (VS, [19]) for the analysis of visual spatial perception in brain damaged patients was investigated. Retest reliability was tested in 20 patients (retest interval: 1 week; range: 1-3) and varied from r = 0.65-0.95 for the different subtests for the "point of subjective equality" and r = 0.39-0.89 for the "interval of uncertainty". In the several investigations concerning the validity of VS. 234 patients and 10 normal subjects participated. In the first place, we found significant relationships of some of the subtests of VS to similar visual-spatial tests, but no relationship to tests of visual object perception. Secondly, we found significant relationships to certain tasks which approximated daily functioning. In summary, the present results demonstrate the objectivity, retest-reliability and validity of VS in brain damaged patients.

Adolescent↗
PubMed1996

Effortful touch with minimum movement: revisited.

The ecological static moment-torque model proposed by C. Carello, P. Fitzpatrick, I. Domaniewicz, T.C. Chan, and M.T. Turvey (1992) does not uniquely explain the perception of rod length by static holding. Guided by a mechanical analysis of the gravitational forces and torques produced in the hand as it statically holds rods of different lengths and materials at different orientations, we offer 2 additional theoretical explanations, the force-torque and weight-percept models. Experiment 1 demonstrates that all 3 models predict perceived rod length with considerable success. Experiment 2 provides clear experimental support for the force-torque and weight-percept models over the static moment-torque model. Experiment 3 pits the former 2 models against each other. Current results favor the weight-percept model. Implications for theories of haptic weight perception and design of a new tactile sensor are also considered.

Adolescent↗
PubMed2005

Eyetracking and selective attention in category learning.

An eyetracking version of the classic Shepard, Hovland, and Jenkins (1961) experiment was conducted. Forty years of research has assumed that category learning often involves learning to selectively attend to only those stimulus dimensions useful for classification. We confirmed that participants learned to allocate their attention optimally. We also found that learners tend to fixate all stimulus dimensions early in learning. This result obtained despite evidence that participants were also testing one-dimensional rules during this period. Finally, the restriction of eye movements to only relevant dimensions tended to occur only after errors were largely (or completely) eliminated. We interpret these findings as consistent with multiple-systems theories of learning which maximize information input in order to maximize the number of learning modules involved, and which focus solely on relevant information only after one module has solved the learning problem.

Association Learning↗
PubMed1976

Body perception upon awakening.

12 male subjects were evaluated with a battery of body perception measures before sleep and just after awakening. Personality measures were also obtained. The results indicated a borderline, but not significant, trend at the time of awakening for the body boundary to be reduced in definiteness; and there were sensations that one's body is more dirty, that its openings are more blocked, and that its size is of less expansive proportions. There were also trends for the traits of stability and reflectiveness to predict bodily experiences upon awakening.

Adult↗
PubMed2005

Perceived arm posture and remote haptic perception of whether an object can be stepped over.

The authors investigated whether the perceived posture of the arm plus a hand-held object influences remote haptic perception of whether an object can be stepped over. Blindfolded participants (N = 20) determined whether they could step over bars at different heights by exploring the bars with a T-shaped rod. The rod was weighted so that the perceived posture of the arm-plus-rod was shifted up, down, or left unchanged. Both the leg length of the participant and the perceived posture of the arm-plus-rod systematically influenced perception of whether the bar could be stepped over. The results highlight the role of perceived posture of the arm-plus-rod in remote haptic perception and have potential implications for the design of navigation aids for the visually impaired.

Adult↗
PubMed1993

Electrophysiological correlates of hierarchical stimulus processing: dissociation between onset and later stages of global and local target processing.

In the discussion of whether the processing of hierarchically structured stimuli proceeds from the more global to the more local level or vice versa, it is frequently assumed that the relative speed of global/local target identification (response time (RT) advantage) and the direction of interference from local/global distractors reflect the order of processing. Studies both in brain-injured patients and in normals, however, have demonstrated that RT advantage and interference are dissociable, leading to the conclusion that they do not provide a valid index of the order of global/local processing. The aim of the present event-related brain potential (ERP) study was to assess electrophysiological correlates of global/local processing and to determine how the relative speed of responding to global and local targets is related to these ERP measurements. In a divided-attention paradigm, subjects were asked to respond to hierarchically structured letter stimuli that contained a target letter either at the global or at the local level. The behavioral results confirmed a dissociation between RT advantage and interference. ERP analysis revealed an early posterior negative component (denoted as N250) as a sign of early global/local target perception. It was found that RT advantage is not a valid measure of the onset nor of the time course of this component. Furthermore, the N250 components to global and local targets exhibited a different time course and a different topographical distribution, suggesting that they are determined by separate processing structures. Together, the behavioral and electrophysiological results support the view that global and local target perception may be mediated by separate brain systems acting, at least initially, in parallel.

Adolescent↗
PubMedDate not supplied

Contribution of peripheral input to length discrimination during use of a precision grip.

This study examined the ability of 63 subjects to discriminate a length difference, using a precision grip with the thumb and the index finger. To assess the relative contribution of different peripheral inputs associated with the discriminative ability of precision grip, three tasks were performed under each of three conditions-normal conditions; when vibratory stimuli were delivered to the forearm muscles; and when a local anesthetic was administered to the index finger. Under the first and second conditions, the length difference detected most frequently was 2.0 mm; in the third task, it was 3.0 mm. When a 100-Hz vibratory stimulus was applied to the forearm muscles, no difference in the threshold for length discrimination was observed for three of seven subjects. After injection of lidocaine into the metacarpophalangeal joint of the index finger, the threshold for length discrimination was significantly different for five of seven subjects. The detected length difference ranged from 1.0 to 4.0 mm. The authors question whether a single peripheral input is likely to make a major contribution to the complex perception that is used for discrimination tasks.

Adolescent↗
PubMed1982

Visual, kinaesthetic and cross-modal judgements of length by normal and clumsy children.

The ability of normal and clumsy children to match the length of lines within and between the modalities of vision and kinesthesis was studied. The clumsy children showed perceptual impairments, as indicated by their poor performance on the visual, kinaesthetic and cross-modal judgements of length and also by their low scores on spatial subtests of the WISC. Variations in motor skill correlated with performance on the visual perceptual measures, but not with performance on the kinaesthetic or cross-modal tasks. The idea that clumsiness may be caused by an impairment of visual perception is discussed, together with some alternative interpretations of this pattern of results.

Agnosia↗
PubMed1977

Subjective frequency in flicker perception.

The discrepancy between the actual flicker frequency and the perceived rate was investigated. We tried to quantify the subjective rate of successive visual flicker by matching it with a second stimulus, the audio flutter. The wave form of each stimulus employed in the present study was sinusoidal. The auditory stimulus employed as a reference was a pure tone which was frequency-modulated by a sine wave. The perceived rate of flicker increases approximately in direct proportion to the frequency presented when target size is small and tends to be lower than the actual rate when target size is large. Perceived rate never exceeds approximately 10 Hz regardless of the presented flicker frequency or the luminance of the target. These tendencies are observed commonly in the fovea and in the periphery of the retina.

Acoustic Stimulation↗