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Results for “SIZE PERCEPTION”

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PubMed1993

Influences of closure, occlusion, and size on the perception of fragmented pictures.

Two experiments examined the ability to recognize a repeated figure in stimuli where only fragments of the figures were presented. Fragments were either closed or open regions presented either with or without an occluder that filled the spaces between the fragments (Experiment 1). Recognition performance was significantly better for open fragments, with or without an occluder, contrary to previous assertions that the occluder is the important factor for recognition. When stimulus size was varied, an occluder hindered recognition performance in the smallest size condition relative to unoccluded stimuli, which were equally easy to recognize across all size conditions (Experiment 2). The size results support the idea of size invariance in object naming. The difficulty in the smallest occluded condition is discussed in terms of differences in global and local processing depending on visual angle and sparsity.

Adult↗
PubMed1998

Realistic weight perception and body size assessment in a racially diverse community sample of dieters.

Recently, a shift in obesity treatment away from emphasizing ideal weight loss goals to establishing realistic weight loss goals has been proposed; yet, what constitutes "realistic" weight loss for different populations is not clear. This study examined notions of realistic shape and weight as well as body size assessment in a large community-based sample of African-American, Asian, Hispanic, and white men and women. Participants were 1893 survey respondents who were all dieters and primarily overweight. Groups were compared on various variables of body image assessment using silhouette ratings. No significant race differences were found in silhouette ratings, nor in perceptions of realistic shape or reasonable weight loss. Realistic shape and weight ratings by both women and men were smaller than current shape and weight but larger than ideal shape and weight ratings. Compared with male dieters, female dieters considered greater weight loss to be realistic. Implications of the findings for the treatment of obesity are discussed.

Adult↗
PubMed2000

The effect of contrast and size scaling on face perception in foveal and extrafoveal vision.

PURPOSE: To determine whether face perception can be equalized across the visual field by scaling size and contrast simultaneously. METHODS: Contrast sensitivities were measured for detection (N = 1) and identification (N = 2-8) of a target face as a function of size (0.4 degrees-10 degrees) across eccentricities (E = 0 degrees-10 degrees). RESULTS: In all conditions contrast sensitivity first increased and then saturated, as a function of stimulus size. Maximum sensitivity (Smax) decreased, whereas critical size (where S = Smax/square root(2)) increased with eccentricity and set size (N). At each set size, sensitivities from all eccentricities could be equated by double scaling--i.e., translation in horizontal (size) and vertical (contrast) dimensions on log-log axes. Similarly, at each eccentricity, data from all set sizes could be superimposed using double scaling. Furthermore, all data could be superimposed onto the foveal detection curve when double scaled according to the equation F = 1 + E/E2i + logN/logN2i + E(logN)/K, where i is horizontal or vertical. This equation incorporates the eccentricity (E2) and set size (N2), where contrast and size double, as well as the interaction term (K). CONCLUSIONS: Double scaling superimposes data. Not only is this possible across set sizes or eccentricities separately, but by combining their effects, a function is provided that collapses all data to a single curve, explaining all performance variation across eccentricity and set size. Our results support the proposition based on numeral recognition that failures of spatial scaling across eccentricities may simply reflect the need for scaling both size and contrast.

Adult↗
PubMed1988

Abnormal perception of food size in anorexia nervosa.

The hypothesis that patients with anorexia nervosa exaggerate the perceived size of food was tested. Video recordings of five items of food and four neutral objects of a similar size were made such that the size of each object increased steadily from half to twice its normal size. Each of the nine objects was placed on a ledge inside a dummy television screen next to the video screen, the food items alternating with the neutral objects, and 20 female patients with anorexia nervosa and 20 female controls matched for age were asked to adjust the size of the video recording to that of the real object. Although there was no overall difference in perceptual accuracy between patients and controls, both groups perceived the food items as being bigger than the neutral objects, the patients exaggerating the size of the food significantly more than the controls. These results imply that patients with anorexia might start eating more easily when admitted if their food were presented as small portions on large plates.

Adolescent↗
PubMed2000

Care giver perception of children's obesity-related health risk: a study of African American families.

OBJECTIVE: To examine care giver perception of children's weight-related health risk in African American families. RESEARCH METHODS AND PROCEDURES: One-hundred and eleven families (representing 48 boys and 63 girls) screened for participation in a diabetes prevention study participated. Care givers completed a health awareness questionnaire that assessed their perception of the child's weight, eating habits, appearance, exercise habits, and health risk. The care givers also reported each subject's family history of obesity, diabetes, and other chronic diseases. After a physical examination, height and weight were used to compute an age- and sex-adjusted body mass index for each child. RESULTS: Despite the fact that a substantial number of children were obese (57%) and super-obese (12%), only 44% of the care givers perceived the child's weight to be a potential health problem. Regression analysis showed that 21% of the variance in parental perception of obesity-related health risk could be predicted by child age, body mass index, perception of frame size, and perception of exercise habits. DISCUSSION: A number of reasons for the apparent minimization of child health risk are discussed, including cultural differences in the acceptance of a large body habitus, lack of knowledge about the connection between childhood obesity and future health risk, and an optimistic bias in the perception of personal health risk.

Adult↗