PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Size Perception”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 19 recordsLinked to original sources
PubMed2000

Object recognition may distort size perception.

Size estimation may be influenced by characteristics recalled about the object viewed. This study evaluated the influence of object familiarity on estimation of size. We compared size estimates of several familiar objects with size estimates of undefined objects matched for dimensions of pattern and color. Those estimating the size of the familiar objects made significantly larger errors than those estimating the size of the undefined objects. In a second study size estimation errors from memory were larger than when objects were directly viewed. Experience with the objects appears to decrease accuracy of estimates of size but errors may be reduced by directly observing the object.

Color Perception↗
PubMed1993

Preattentive processing of object size: implications for theories of size perception.

Information about the visual angle size of objects is important for maintaining object constancy with variations in viewing distance. Although human observers are quite accurate at judging spatial separations (or cross-sectional size), they are prone to error when there are other spans nearby, as in classical illusions such as the Müller-Lyer illusion. It is possible to reconcile these aspects of size perception by assuming that the size domain is sampled sparsely. It was shown by means of a visual search procedure that the size of objects is processed preattentively and in parallel across the visual field. It was demonstrated that an object's size, rather than its boundary curvature or spatial-frequency content, provides the basis for parallel visual search. It was also shown that texture borders could be substituted for luminance borders, indicating that object boundaries at the relevant spatial scale provide the input to size perception. Parallel processing imposes a severe computational constraint which provides support for the assumption of sparse sampling. An economical model based on several broadly tuned layers of size detectors is proposed to account for the parallel extraction of size, the Weberian behaviour of size discrimination, and the occurrence of strong interference effects in the size domain.

Attention↗
PubMed1996

A motor signal and "visual" size perception.

Recent models of the visual system in primates suggest that the mechanisms underlying visual perception and visuomotor control are implemented in separate functional streams in the cerebral cortex. However, a little-studied perceptual illusion demonstrates that a motor-related signal representing arm position can contribute to the visual perception of size. The illusion consists of an illusory size change in an afterimage of the hand when the hand is moved towards or away from the subject. The motor signal necessary for the illusion could be specified by feedforward and/or feedback sources (i.e. efference copy and/or proprioception/kinesthesis). We investigated the nature of this signal by measuring the illusion's magnitude when subjects moved their own arm (active condition, feedforward and feedback information available), and when arm movement was under the control of the experimenter (passive condition, feedback information available). Active and passive movements produced equivalent illusory size changes in the afterimages. However, the illusion was not obtained when an after-image of subject's hand was obtained prior to movement of the other hand from a very similar location in space. This evidence shows that proprioceptive/kinesthetic feedback was sufficient to drive the illusion and suggests that a specific three-dimensional registration of proprioceptive input and the initial afterimage is necessary for the illusion to occur.

Afterimage↗
PubMed1992

An experimental study of the effect of mood on body size perception.

The study presented is an experimental investigation of the effect of mood on body size perception. Female students estimated their body size and indicated their degree of dissatisfaction with their body size before and after the induction of a negative or positive mood state. Compared with women who received the positive induced mood, the induction of low mood led to greater disturbances in body size perception in the form of a tendency to overestimate their body size more and significantly greater dissatisfaction with their body size. Furthermore, among the women who received the negative mood condition, compared with those with little or no concern with their body shape, for those with such concerns the induction of low mood led to greater disturbances in body size perception in the form of overestimating their body size significantly more and a tendency towards greater dissatisfaction with their body size. These findings suggest that depressed mood may play an important role in determining the extent of disturbance in body size perception in clinical populations.

Adult↗
PubMed2001

Size perception in hemianopia and neglect.

Some debate remains as to whether underestimation of the horizontal size of objects in the left part of visual space is a general disturbance in spatial neglect. The issue is unclear because size perception may be influenced by factors other than neglect, e.g. visual field defects such as hemianopia. To disentangle these effects, we compared the performance of patients with pure neglect, pure hemianopia or both on the same size-comparison test. Whereas pure neglect was accompanied by misperception of horizontal object size, patients with pure hemianopia showed an even greater impairment of size perception. Accordingly, the area of maximum lesion overlap of these patients with impaired size perception was not centred around the parietotemporal cortex, which is typically associated with spatial neglect, but rather was found in the occipital lobe (Brodmann areas 17 and 18). The results suggest that spatial neglect is not an inevitable consequence of distorted size perception. The perceptual distortion of objects in the leftward parts of visual space is not sufficient to account for the occurrence of visuospatial neglect.

Aged↗
PubMed2004

Size perception is less context-sensitive in males.

Context sensitivity of size perception has previously been used to study individual differences related to the distinction between local, analytic, or field-independent and global, holistic, or field-dependent perceptual styles. For example, it has been used in several recent studies of autistic spectrum disorders, which may involve an excessive bias toward local processing. Autism is much more common in males, and there is evidence that this may be in part because males in general tend to be less context-sensitive than females, and thus are more affected by conditions that further reduce context sensitivity. There is also evidence that a bias to local processing is more common in professions that require attention to detail. Context sensitivity of size perception was therefore studied as a function of sex and academic discipline in sixty-four university staff and students by a simple, sensitive, and specific psychophysical measure based on the Ebbinghaus illusion. The results show that in this task males are on average less context-sensitive than females, that the overlap is large, and that subjects with very high or very low context sensitivity tend to have the sex and profession predicted by the above hypotheses.

Discrimination, Psychological↗
PubMed1996

Do Polynesians still believe that big is beautiful? Comparison of body size perceptions and preferences of Cook Islands, Maori and Australians.

AIMS: To examine body size perceptions in a group of Polynesians from the Cook Islands and compare these with perceptions of Australians of European decent. METHODS: Residents of Tutakimoa village on the island of Rarotonga, Cook Islands completed a questionnaire on body size perception (83 females, 49 males, 80% response rate). The responses were compared with the same number of Australian subjects who were matched for sex, age and body mass index (BMI). Culturally appropriate, graded sets of photographs (one female and one male for each ethnic group) were used as the stimuli for questions on body perception. RESULTS: Cook Islands women were the most accurate in their perception of their current size; other groups overestimated. All groups preferred to be smaller, particularly women, with similar preferences (BMI 23-24) in women of both ethnic groups. Cook Islands subjects chose larger ideal sizes than Australians for both females (BMI 24.4 vs 22.5) and males (BMI 27 vs 24.2). CONCLUSIONS: The traditional Polynesian concepts of very large body sizes being considered healthy and attractive are not evident in the modern day Cook Islanders. The excessive pursuit of western fashions for small female body size may have longer term detrimental effects in Polynesian women.

Adolescent↗
PubMed2001

The independence of size perception and distance perception.

Research on distance perception has focused on environmental sources of information, which have been well documented; in contrast, size perception research has focused on familiarity or has relied on distance information. An analysis of these two parallel bodies of work reveals their lack of equivalence. Furthermore, definitions of familiarity need environmental grounding, specifically concerning the amount of size variation among different tokens of an object. To demonstrate the independence of size and distance perception, subjects in two experiments were asked to estimate the sizes of common objects from memory and then to estimate both the sizes and the distances of a subset of such objects displayed in front of them. The experiments found that token variation was a critical variable in the accuracy of size estimations, whether from memory or with vision, and that distance had no impact at all on size perception. Furthermore, when distance information was good, size had no effect on distance estimation; in contrast, at far distances, the distances to token variable or unknown objects were estimated with less accuracy. The results suggest that size perception has been misconceptualized, so that the relevant research to understand its properties has not been undertaken. The size-distance invariance hypothesis was shown to be inadequate for both areas of research.

Adult↗
PubMed2005

Is size perception based on monocular distance cues computed automatically?

The study reported here examined whether size perception based on monocular distance cues is computed automatically. Participants were presented with a picture containing distance cues, which was superimposed with a pair of digits differing in numerical value. One digit was presented so as to be perceived as closer than the other. The digits were of similar physical size but differed in their perceptual size. The participants' task was to decide which digit was numerically larger. It was found that the decision took longer and resulted in more errors when the perceptual size of the numerically larger digit was smaller than the perceptual size of the numerically smaller digit. These results show that perceived size affects performance in a task that does not require size or distance computation. Hence, for the first time, there is empirical support for the working assumption of the visual perception approach that size perception based on monocular distance cues is computed automatically.

Cues↗
PubMed1997

Black-white differences in body size perceptions and weight management practices among adolescent females.

OBJECTIVE: This study compares body size perceptions and weight management practices of black and white adolescent females. DESIGN: Subjects were selected through a statewide, three-stage sampling procedure designed to provide a sample statistically representative of high school students in South Carolina. SUBJECTS: Participants included black (n = 1824) and white (n = 2256) females, 14-18 years of age, enrolled in South Carolina public high schools. METHODS: Respondents were asked to assess their perceived body size as overweight, underweight, or about right. Self-reported weight management practices included dieting (reducing caloric intake), exercise, and other methods (including diet pills and vomiting). Chisquare analysis was used to assess the differences in body size perception and weight management behaviors. Polychotomous logistic regression was performed to examine association while controlling for socioeconomic status. RESULTS: Forty-one percent of the white adolescents and 29% of the black adolescents perceive themselves as overweight (p < 0.005). In the week prior to the survey, 28% of the white adolescents and 13% of the black adolescents reported dieting 34% of the while versus 23% of the black adolescents reported exercising to lose weight; and 45% of the white and 16% of the black students reported both dieting and exercising. Polychotomous logistic regression analysis showed that white adolescent girls were almost twice as likely to perceive themselves as overweight as black adolescent girls. The white students had 6.04 [95% confidence interval (CI), 1.77, 20.67] times the odds of using pills and vomiting and 3.76 (95% CI, 2.99, 4.72) times the odds of engaging in dieting and exercising as methods of weight management compared to the black students. CONCLUSIONS: These findings suggest that white adolescents are more likely to perceive themselves as overweight than black adolescents and are more likely to engage in unhealthy weight management practices than black adolescents.

Adolescent↗
PubMed1992

Body size perception and body satisfaction in restrained and unrestrained eaters.

In 21 restrained and 20 unrestrained eaters body size perception was measured using the video distortion technique (VDT), the image marking procedure (IMP) and the kinesthetic size estimating apparatus (KSEA). Body satisfaction was assessed by questionnaires (Body Shape Questionnaire, Dieting scale of the Eating Attitudes Test). Restrained eaters showed no systematic over- or underestimation of the body size but less perceptual accuracy (in VDT and KSEA). Furthermore, they were clearly more dissatisfied with their bodies than unrestrained eaters. Both findings were unrelated to each other. In both groups depressive mood or thoughts seemed to be associated with body dissatisfaction but not with body size misperception. Objective body measures (body mass index, body fat content) were not related to either body size perception or body satisfaction. The findings suggest that a perceptual uncertainty in regard to body size (either for visual or for somatosensory aspects) has already developed in restrained eaters, which may constitute a predisposition for more overt forms of body size misperception as found in eating disorder patients.

Behavior Therapy↗
PubMed1994

Body size perceptions and eating attitudes in elderly men.

The majority of studies on eating attitudes, dieting and body size perceptions have focused on young adults and women. This study examined these attitudes in 334 black and white men, ages 55 to 98 years, who were members of the Charleston Heart Study cohort. Associations of the eating attitude variable with race, education and weight status were examined. Eighty-two percent of the overweight white men studied had dieted to lose weight, whereas only 49% of slimmer white men had dieted. In contrast, overweight black men did not diet more than slimmer black men. Overall black men dieted less than white men (37% reported dieting). Black men who were high school graduates were 1.3 times more likely to have dieted than were less educated black men. Overweight white men were over twice as likely as slimmer white men to feel guilty after overeating. This difference was not found in overweight versus slimmer black men. Education was not associated with measured body mass index (BMI) or perceived or ideal body size. However, there were some racial differences in these variables. White men preferred to be slightly thinner than black men (ideal BMI 25.6 vs. 26.1 kg/m2), and the difference between actual and desired BMI was 0.6 kg/m2 greater in white than in black men. These results indicate that effects of race and weight status on eating restraint and body size perceptions seen in younger subjects and in women are also present, at least to some degree, in elderly men.

Aged↗
PubMed2006

The influence of size perception and internal modeling on the control process while lifting.

The present study sought to verify object size perception through internal modeling while lifting an object. Electromyography (EMG) activity of the upper limb muscles was recorded while 20 healthy females alternately lifted two containers of the same weight, but were unequal in size. When subjects lifted the small container, a significant increase was observed in the EMG activity. Most subjects determined that the small container was heavier than the large container, and predicted that the large container would be heavier than the small container due to size difference. The results may be explained by supporting that subjects predict object weight based on perception of size through internal modeling; however, predictions are cross-checked and modified through sensory feedback based on subjective weight.

Adult↗
PubMed2006

Body-size perception, body-esteem, and parenting history in college women reporting a history of child abuse.

This study investigated the relations among physical, emotional, and sexual abuse up to adolescence and subsequent perception of body size, detection of changes in body size, and body-esteem. The role of parenting history in abused participants was also examined. 38 college undergraduate women, half of whom had been abused, reported instances of abuse, childhood parenting history, and current body-esteem. A recently developed software program of Gardner and Boice was used to present a series of distorted frontal profiles of each participant's own body for the women to rate as being too wide or too thin. A psychophysical procedure called adaptive probit estimation was used to measure the amount of over- and underestimation of these ratings and whether these changes were statistically significant. Analysis showed abused participants had distorted perceptions of body size, although the direction of the distortion was not consistent. There was no difference in detection of changes in body size. Abused and nonabused participants differed on measures of body-esteem and on ratings of most parenting experiences, including experiences with both mothers and fathers.

Adolescent↗
PubMed1994

Perceived size of familiar objects and the theory of off-sized perceptions.

In three experiments, I examined the claim (Gogel, 1969; Gogel & Newton, 1969) that familiar objects viewed under reduced stimulus conditions frequently appear to be off-sized (i.e., larger or smaller than normal). In Experiments 1 and 2, I presented images of different familiar objects, one at a time, at distances of 1 and 2 m from the observers. The images were normal-, large-, or small-sized versions of familiar objects, and the observers judged the perceived size of each object relative to its familiar normal size. In Experiment 3, I presented normal-, large-, and small-sized versions of the same familiar object at physical distances of 1 and 2 m. The pattern of size results was similar across the three experiments. In general, normal-sized objects appeared normal-to small-sized at the 1-m distance and small-sized at the 2-m distance; small-sized objects appeared small-sized at the 1-m distance and even smaller at the 2-m distance; and large-sized objects appeared normal- to large-sized at the 1-m distance and normal- to small-sized at the 2-m distance. The distance results of Experiment 3 indicated that familiar size was an effective determinant of reported distance. These results are consistent with Gogel's theory of off-sized perceptions and, more generally, with the claim that familiar size is not an important determinant of perceived size.

Adult↗
PubMed1995

Comparison of three psychophysical techniques for estimating body-size perception.

Perception of body size was recorded for 63 university students (M age = 25.3 yr., 41 women) who estimated their own body size using three methods. Using the method of adjustment, subjects over- or underestimated their body size. A signal-detection analysis indicated that subjects were sensitive to detecting a 4% distortion in body size and that there was no systematic bias for reporting distortion as present or absent. Scores on the adaptive probit estimation task were significantly correlated with values for point of subjective equality and the size judgements with the method of adjustment. Over-all, this experiment demonstrated adaptive probit estimation as a reliable indicator of perceived body size, sensitivity in detecting size distortion, and response bias in making body-size judgements.

Adolescent↗