Body image distortion in anorexics as a non-sensory phenomenon: a signal detection approach

Visual Self-Misperception in Eating Disorders

Many who suffer from eating disorders claim that they see themselves as "fat". Despite decades of research into the phenomenon, behavioural evidence has failed to confirm that eating disorders involve visual misperception of own-body size. I illustrate the importance of this phenomenon for our understanding of perceptual processing, outline the challenges involved in experimentally confirming it, and provide solutions to those challenges.

Use of a real-life practical context changes the relationship between implicit body representations and real body measurements

A mismatch exists between people's mental representations of their own body and their real body measurements, which may impact general well-being and health. We investigated whether this mismatch is reduced when contextualizing body size estimation in a real-life scenario. Using a reverse correlation paradigm, we constructed unbiased, data-driven visual depictions of participants' implicit body representations. Across three conditions-own abstract, ideal, and own concrete body-participants selected the body that looked most like their own, like the body they would like to have, or like the body they would use for online shopping. In the own concrete condition only, we found a significant correlation between perceived and real hip width, suggesting that the perceived/real body match only exists when body size estimation takes place in a practical context, although the negative correlation indicated inaccurate estimation. Further, participants who underestimated their body size or who had more negative attitudes towards their body weight showed a positive correlation between perceived and real body size in the own abstract condition. Finally, our results indicated that different body areas were implicated in the different conditions. These findings suggest that implicit body representations depend on situational and individual differences, which has clinical and practical implications.

Visual mapping of body image disturbance in anorexia nervosa reveals objective markers of illness severity

Body image disturbance (BID) is a core feature of eating disorders, for which there are few objective markers. We examined the feasibility of a novel digital tool, "Somatomap", to index BID related to anorexia nervosa (AN) severity. Fifty-five AN inpatients and 55 healthy comparisons (HC) outlined their body concerns on a 2-Dimensional avatar. Next, they indicated sizes/shapes of body parts for their current and ideal body using sliders on a 3-Dimensional avatar. Physical measurements of corresponding body parts, in cm, were collected for reference. We evaluated regional differences in BID using proportional z-scores to generate statistical body maps, and multivariate analysis of covariance to assess perceptual discrepancies for current body, ideal body, and body dissatisfaction. The AN group demonstrated greater regional perceptual inaccuracy for their current body than HC, greater discrepancies between their current and ideal body, and higher body dissatisfaction than HCs. AN body concerns localized disproportionately to the chest and lower abdomen. The number of body concerns and perceptual inaccuracy for individual body parts was strongly associated with Eating Disorder Examination Questionnaire (Global EDE-Q) scores across both groups. Somatomap demonstrated feasibility to capture multidimensional aspects of BID. Several implicit measures were significantly associated with illness severity, suggesting potential utility for identifying objective BID markers.

[Use of virtual reality in eating disorders]

Virtual reality is a new technology that can be used to model an environment with which an individual can interact using all five senses. It is notably used in psychiatry for anxiety disorders and addictions, and its use in eating disorders has been growing in recent years. Indeed, virtual reality offers interesting advantages, such as its ability to personalize any environment, which is also more secure and controllable. Recent studies show promising results in the understanding, evaluation, and therapeutic management of eating disorders. The use of avatars in anorexia nervosa allows for a correct assessment of the perceptual (body image distortion) and cognitive-affective (body dissatisfaction) components of the body image disorder in a similar way to conventional methods, but also for a better understanding of them. Moreover, avatars allow the development of innovative therapeutic protocols and are thus used in the context of exposure therapy. The new body swapping protocol, based on a multisensory illusion, offers particularly promising results in the reduction of body image disorder. For bulimia nervosa and binge eating disorder, virtual reality has made it possible to better characterize the triggering mechanisms of binge eating episodes through studies that have observed different responses to food-related environments and stimuli. At the therapeutic level, virtual reality cue exposure therapy has the most empirical support. Its aim is to reduce or eliminate the anxiety and craving felt by a patient in response to exposure to food or other food-related cues by preventing the patient from consuming food, and results show clear reductions in anxiety, craving and binge eating episodes. While all these results seem to indicate a bright future for virtual reality in eating disorders, further studies are needed to validate the positive impact of its use, but also its limitations. Notably, cyber sickness could alter the smooth running of virtual reality therapy sessions by causing nausea and disorientation. Moreover, it is important to verify that a therapeutic protocol does not lose its effectiveness when it is transposed into virtual reality. However, virtual reality seems to be a therapeutic tool that is better accepted by patients, and even better by adolescents, which is very interesting for eating disorders since adolescents are the most affected. Virtual reality could therefore help motivate patients to pursue treatment and reduce the dropout rate while offering good therapeutic results. Thus, studies conducted in recent years have shown that virtual reality is a promising tool in the understanding, assessment and treatment of eating disorders, and future research should confirm this, particularly in the adolescent population.

Body perception treatment, a possible way to treat body image disturbance in eating disorders: a case-control efficacy study

BACKGROUND

The body image disturbance (BID) is a common symptom in eating disorders, often observed and described in anorexia nervosa (AN) and bulimia nervosa (BN). Recently, this symptom has also been observed in binge eating disorder (BED). The research underlines that the BID presents three different altered components: affective, cognitive, and perceptual one. Current treatments for BID have mainly focused on the affective and cognitive components. Nowadays, the need emerges for treatments focused also on the perceptual component of the BID. In this paper, we present the results of an efficacy study on the body perception treatment (BPT), a new treatment for BID focused on the perceptual component of the disorder.

OBJECTIVE

We looked for an additional treatment effect on a protocol for ED inpatients to evaluate the efficacy of BPT. We performed the study through statistical analysis of admission and discharge scores.

METHODS

We conducted a case-control study in a hospital ward specialized in eating disorders. Two groups were identified: the control group (TAU; N = 91) and the experimental group (TAU + BPT; N = 91). The experimental group performed BTP activities in addition to the treatment at usual. All patients in both groups had an eating disorder diagnosis (AN, BN, BED and EDNOS/OSFED). Sampling occurred on a time basis and not by randomization. Moreover, all patients admitted in the ED hospital ward in the time frame considered (from end-2009 to mid-2017) were included in the study. BPT activities were introduced in mid-2013 and three psychometric instruments upon entry and discharge were used: Symptom Check List-90 (SCL-90) to measure the general psychopathological state; the Eating Disorder Inventory-3 (EDI-3) to estimate the incidence of personality traits strongly correlated to eating disorders; the body uneasiness test (BUT) to measure the body uneasiness. We performed a pre/post analysis for both groups; we studied the additional effect of the treatment through deltas analysis of the three questionnaires (Δ = assessment at discharge - assessment at the entrance). Data were analyzed using the Student T and the Wilcoxon rank-sum test.

RESULTS

The pre/post analysis showed statistically significant improvement in both conditions (TAU and TAU + BPT) in the general psychopathological state (SCL-90) and in the incidence of personality traits (EDI-3). Improvements in body uneasiness (BUT) were observed only in the experimental group (TAU + BPT). Furthermore, the analysis of the deltas shows more significant improvements in TAU + BPT compared to TAU in all the variables considered.

CONCLUSION

We found an additional effect of the BPT on TAU. The usual ED protocol added with BPT activities showed significantly better clinical results. We have interpreted these results in light of recent developments in the neuroscientific field of body image.

LEVEL OF EVIDENCE

Level II: controlled trial without randomization.

Visuo-tactile shape perception in women with Anorexia Nervosa and healthy women with and without body concerns

A key feature of Anorexia Nervosa is body image disturbances, the study of which has focused mainly on visual and attitudinal aspects, did not always contain homogeneous groups of patients, and/or did not evaluate body shape concerns of the control group. In this study, we used psychophysical methods to investigate the visual, tactile and bimodal perception of elliptical shapes in a group of patients with Anorexia Nervosa (AN) restricting type and two groups of healthy participants, which differed from each other by the presence of concerns about their own bodies. We used an experimental paradigm designed to test the hypothesis that the perceptual deficits in AN reflect an impairment in multisensory integration. The results showed that the discrimination thresholds of AN patients are larger than those of the two control groups. While all participants overestimated the width of the ellipses, this distortion was more pronounced in AN patients and, to a lesser extent, healthy women concerned about their bodies. All groups integrated visual and tactile information similarly in the bimodal conditions, which does not support the multi-modal integration impairment hypothesis. We interpret these results within an integrated model of perceptual deficits of Anorexia Nervosa based on a model of somatosensation that posits a link between object tactile perception and Mental Body Representations. Finally, we found that the participants' perceptual abilities were correlated with their clinical scores. This result should encourage further studies that aim at evaluating the potential of perceptual indexes as a tool to support clinical practices.

Comparison of body image evaluation by virtual reality and paper-based figure rating scales in adolescents with anorexia nervosa: retrospective study

PURPOSE

Assessment of the symptoms of body image disorder (BID) is crucial in anorexia nervosa (AN). Recent technological advancements such as virtual reality (VR) have improved the visual perception with 3D avatars and the feeling to be the avatar with the immersive conditions. This retrospective study examines the hypothesis that VR with standardized 3D avatars would improve body image perception and then body image evaluation by adolescents with AN, compared to the paper-based figure rating scales (FRS).

METHODS

Data of 31 female adolescents with AN were retrospectively studied. Paired data of perceived and desired body forms in addition to body perception index (BPI) (p = 0.2) and body dissatisfaction (p = 0.6), obtained by both VR and FRS were compared. Furthermore, correlation with validated psychometric questionnaires was also studied. Head-tracking technology allowed for the implicit measurement of explicit choices of patients.

RESULTS

Participants with AN overestimated own body size regardless of the assessment tool used. BPI and body dissatisfaction did not differ significantly between FRS and VR. VR-based evaluation was correlated with the psychometric parameters BID and body dissatisfaction. Head tracking revealed significantly longer participant engagement with avatars representing malnutrition and underweight states, while those least engaged corresponded to obesity.

CONCLUSIONS

Results of BID evaluation by VR standardized 3D avatars are comparable to those obtained by paper-based FRS. These findings suggest that comparable results obtained by both tools of evaluation reflect primarily the role of affective-cognitive perturbation in BID. The perceptive component could be better evaluated using biometric-enhanced assessment tools.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study (evaluation data retrospectively studied).

Which Body Would You Like to Have? The Impact of Embodied Perspective on Body Perception and Body Evaluation in Immersive Virtual Reality

In this experiment, we aimed to measure the conscious internal representation of one's body appearance and allow the participants to compare this to their ideal body appearance and to their real body appearance. We created a virtual representation of the internal image participants had of their own body shape. We also created a virtual body corresponding to the internal representation they had of their ideal body shape, and we built another virtual body based on their real body measures. Participants saw the three different virtual bodies from an embodied first-person perspective and from a third-person perspective and had to evaluate the appearance of those virtual bodies. We observed that female participants evaluated their real body as more attractive when they saw it from a third-person perspective, and that their level of body dissatisfaction was lower after the experimental procedure. We believe that third-person perspective allowed female participants to perceive their real body shape without applying the negative prior beliefs usually associated to the "self", and that this resulted in a more positive evaluation of their body shape. We speculate that this method could be applied with patients suffering from eating disorders, by making their body perception more realistic and therefore improve their body satisfaction.

Are attitudinal and perceptual body image the same or different? Evidence from high-level adaptation

We used a high-level adaptation paradigm to distinguish between two hypotheses: (1) perceptual and attitudinal body image measurements reflect conceptually different mechanisms which are statistically independent of each other; (2) attitudinal (e.g., questionnaire) and perceptual (e.g., visual yes-no) body image tasks represent two different ways of measuring exactly the same construct. Forty women, with no history of eating disorders, carried out the experiment. Each participant carried out five adaptation blocks, with adapting stimuli representing female bodies at: extreme-low body mass index (BMI), mid-low BMI, actual BMI of the observer, mid-high BMI, and extreme-high BMI. Block order was randomized across participants. The main outcome variable was percentage error in participants' self-estimates of body size, measured post-adaption. In regressions of this percentage error on the strength of the adapting stimuli together with observers' attitudinal body image as a covariate, we found positive regression slopes and no evidence for any interaction between the fixed effects. Therefore, we conclude that perceptual and attitudinal body image mechanisms are indeed independent of each other. In the light of this evidence, we discuss how people with eating disorders, like anorexia nervosa, may come to over-estimate their body size.

Immersive Virtual Reality and Virtual Embodiment for Pain Relief

A significant body of experimental evidence has demonstrated that it is possible to induce the illusion of ownership of a fake limb or even an entire fake body using multisensory correlations. Recently, immersive virtual reality has allowed users to experience the same sensations of ownership over a virtual body inside an immersive virtual environment, which in turn allows virtual reality users to have the feeling of being "embodied" in a virtual body. Using such virtual embodiment to manipulate body perception is starting to be extensively investigated and may have clinical implications for conditions that involve altered body image such as chronic pain. Here, we review experimental and clinical studies that have explored the manipulation of an embodied virtual body in immersive virtual reality for both experimental and clinical pain relief. We discuss the current state of the art, as well as the challenges faced by, and ideas for, future research. Finally, we explore the potentialities of using an embodied virtual body in immersive virtual reality in the field of neurorehabilitation, specifically in the field of pain.

The visual cues that drive the self-assessment of body size: Dissociation between fixation patterns and the key areas of the body for accurate judgement

A modified version of the bubbles masking paradigm was used in three experiments to determine the key areas of the body that are used in self-estimates of body size. In this paradigm, parts of the stimuli are revealed by several randomly allocated Gaussian "windows" forcing judgements to be made based on this partial information. Over multiple trials, all potential cues are sampled, and the effectiveness of each window at predicting the judgement is determined. The modified bubbles strategy emphasises the distinction between central versus edge cues and localises the visual features used in judging one's own body size. In addition, eye-movements were measured in conjunction with the bubbles paradigm and the results mapped onto a common reference space. This shows that although observers fixate centrally on the torso, they are actually directing their visual attention to the edges of the torso to gauge body width as an index of body size. The central fixations are simply the most efficient way of positioning the eye to make this estimation. Inaccurate observers are less precise in their central fixations and do not evenly allocate their attention to both sides of the torso's edge, illustrating the importance of efficiently sampling the key information.

Distorted body image influences body schema in individuals with negative bodily attitudes

There is now a considerable body of evidence to suggest that internal representations of the body can be meaningfully separated into at least two general levels; body image as a perceptual construct and body schema as a motor metric. However, recent studies with eating disordered individuals have suggested that there may in fact be more interaction between these two representations than first thought. We aimed to investigate how body image might act to influence body schema within a typical, healthy population. 100 healthy adult women were asked to judge the smallest gap between a pair of sliding doors that they could just pass through. We then determined whether these estimates were sufficient to predict the size of the smallest gap that they could actually pass through, or whether perceptual and attitudinal body image information was required in order to make these predictions. It was found that perceptual body image did indeed mediate performance on the egocentric (but not allocentric) motor imagery affordance task, but only for those individuals with raised body image concerns and low self-esteem; body schema was influenced by both the perceptual and attitudinal components of body image in those with more negative bodily attitudes. Furthermore, disparities between perceived versus actual size were associated with body parts that had larger variations in adipose/muscle-dependent circumference. We therefore suggest that it may be the affective salience of a distorted body representation that mediates the degree to which it is incorporated into the current body state.

Assessing body image in anorexia nervosa using biometric self-avatars in virtual reality: Attitudinal components rather than visual body size estimation are distorted

BACKGROUND

Body image disturbance (BID) is a core symptom of anorexia nervosa (AN), but as yet distinctive features of BID are unknown. The present study aimed at disentangling perceptual and attitudinal components of BID in AN.

METHODS

We investigated n = 24 women with AN and n = 24 controls. Based on a three-dimensional (3D) body scan, we created realistic virtual 3D bodies (avatars) for each participant that were varied through a range of ±20% of the participants' weights. Avatars were presented in a virtual reality mirror scenario. Using different psychophysical tasks, participants identified and adjusted their actual and their desired body weight. To test for general perceptual biases in estimating body weight, a second experiment investigated perception of weight and shape matched avatars with another identity.

RESULTS

Women with AN and controls underestimated their weight, with a trend that women with AN underestimated more. The average desired body of controls had normal weight while the average desired weight of women with AN corresponded to extreme AN (DSM-5). Correlation analyses revealed that desired body weight, but not accuracy of weight estimation, was associated with eating disorder symptoms. In the second experiment, both groups estimated accurately while the most attractive body was similar to Experiment 1.

CONCLUSIONS

Our results contradict the widespread assumption that patients with AN overestimate their body weight due to visual distortions. Rather, they illustrate that BID might be driven by distorted attitudes with regard to the desired body. Clinical interventions should aim at helping patients with AN to change their desired weight.

Investigating Body Image Disturbance in Anorexia Nervosa Using Novel Biometric Figure Rating Scales: A Pilot Study

This study uses novel biometric figure rating scales (FRS) spanning body mass index (BMI) 13.8 to 32.2 kg/m² and BMI 18 to 42 kg/m² . The aims of the study were (i) to compare FRS body weight dissatisfaction and perceptual distortion of women with anorexia nervosa (AN) to a community sample; (ii) how FRS parameters are associated with questionnaire body dissatisfaction, eating disorder symptoms and appearance comparison habits; and (iii) whether the weight spectrum of the FRS matters. Women with AN (n = 24) and a community sample of women (n = 104) selected their current and ideal body on the FRS and completed additional questionnaires. Women with AN accurately picked the body that aligned best with their actual weight in both FRS. Controls underestimated their BMI in the FRS 14-32 and were accurate in the FRS 18-42. In both FRS, women with AN desired a body close to their actual BMI and controls desired a thinner body. Our observations suggest that body image disturbance in AN is unlikely to be characterized by a visual perceptual disturbance, but rather by an idealization of underweight in conjunction with high body dissatisfaction. The weight spectrum of FRS can influence the accuracy of BMI estimation. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

Body size estimation in women with anorexia nervosa and healthy controls using 3D avatars

A core feature of anorexia nervosa is an over-estimation of body size. However, quantifying this over-estimation has been problematic as existing methodologies introduce a series of artefacts and inaccuracies in the stimuli used for judgements of body size. To overcome these problems, we have: (i) taken 3D scans of 15 women who have symptoms of anorexia (referred to henceforth as anorexia spectrum disorders, ANSD) and 15 healthy control women, (ii) used a 3D modelling package to build avatars from the scans, (iii) manipulated the body shapes of these avatars to reflect biometrically accurate, continuous changes in body mass index (BMI), (iv) used these personalized avatars as stimuli to allow the women to estimate their body size. The results show that women who are currently receiving treatment for ANSD show an over-estimation of body size which rapidly increases as their own BMI increases. By contrast, the women acting as healthy controls can accurately estimate their body size irrespective of their own BMI. This study demonstrates the viability of combining 3D scanning and CGI techniques to create personalised realistic avatars of individual patients to directly assess their body image perception.

Depictive and metric body size estimation in anorexia nervosa and bulimia nervosa: A systematic review and meta-analysis

A distorted representation of one's own body is a diagnostic criterion and core psychopathology of both anorexia nervosa (AN) and bulimia nervosa (BN). Despite recent technical advances in research, it is still unknown whether this body image disturbance is characterized by body dissatisfaction and a low ideal weight and/or includes a distorted perception or processing of body size. In this article, we provide an update and meta-analysis of 42 articles summarizing measures and results for body size estimation (BSE) from 926 individuals with AN, 536 individuals with BN and 1920 controls. We replicate findings that individuals with AN and BN overestimate their body size as compared to controls (ES=0.63). Our meta-regression shows that metric methods (BSE by direct or indirect spatial measures) yield larger effect sizes than depictive methods (BSE by evaluating distorted pictures), and that effect sizes are larger for patients with BN than for patients with AN. To interpret these results, we suggest a revised theoretical framework for BSE that accounts for differences between depictive and metric BSE methods regarding the underlying body representations (conceptual vs. perceptual, implicit vs. explicit). We also discuss clinical implications and argue for the importance of multimethod approaches to investigate body image disturbance.

Brazilian Photographic Figure Rating Scale: Development and Psychometric Investigation

This study reports on the development, reliability, and validity of a new instrument for obtaining respondents' body image perception, the Brazilian Photographic Figure Rating Scale (BPFRS). This instrument consists of eight photographic images (seven distorted and one accurate) of respondents themselves in standardized poses, taken just prior to requesting respondents to make self-ratings on the instrument. Participants involved in developing and evaluating this instrument were 142 Brazilian women (age 21.8 ± 3.0 years). Ten experts assessed content validity and showed high agreement (defined by ratings of 4-5 on a 5-point scale) with items measuring underlying constructs and high (>70%) interrater agreement. A Pearson correlation demonstrated convergence between the BPFRS and other related scales; a positive correlation was also evident between actual and respondent-perceived body mass index. Both test-retest and Kappa confirmed temporal stability. These findings indicate that the BPFRS can accurately and reliably assess body image dissatisfaction and body perception in young women by deploying realistic, personalized images as stimuli for self-ratings. Implications for further research and treatment of body image problems are discussed.

The Perceptual and Affective Components of Body Image Disturbances in Anorexic and Normal Females

The literature is inundated with studies reporting the body image experiences of anorexia nervosa patients and normal weight people. Such studies have not, however, yielded consistent results. The present study reinvestigated the issue bearing in mind the theoretical and methodological limitations of previous research. The perceptual and affective aspects of body image were investigated in 11 white, female anorexic patients and 51 white, female psychology undergraduate university students. A combination of the movable caliper technique and image-marking procedure was used to assess body size perception, that is, the perceptual aspect, and the Body Cathexis scale was used to assess body satisfaction, that is, the affective aspect. It was found that anorexic females overestimate the width of their waist and thighs significantly more than normal females ( p < 0.05) and that they have a significantly lower body satisfaction ( p < 0.001). It was concluded that the DSM IV criterion of a disturbance in body image has specific diagnostic relevance in anorexia nervosa.

Spinal cord injury affects the interplay between visual and sensorimotor representations of the body

The brain integrates multiple sensory inputs, including somatosensory and visual inputs, to produce a representation of the body. Spinal cord injury (SCI) interrupts the communication between brain and body and the effects of this deafferentation on body representation are poorly understood. We investigated whether the relative weight of somatosensory and visual frames of reference for body representation is altered in individuals with incomplete or complete SCI (affecting lower limbs’ somatosensation), with respect to controls. To study the influence of afferent somatosensory information on body representation, participants verbally judged the laterality of rotated images of feet, hands, and whole-bodies (mental rotation task) in two different postures (participants’ body parts were hidden from view). We found that (i) complete SCI disrupts the influence of postural changes on the representation of the deafferented body parts (feet, but not hands) and (ii) regardless of posture, whole-body representation progressively deteriorates proportionally to SCI completeness. These results demonstrate that the cortical representation of the body is dynamic, responsive, and adaptable to contingent conditions, in that the role of somatosensation is altered and partially compensated with a change in the relative weight of somatosensory versus visual bodily representations.

Body size overestimation and its association with body mass index, body dissatisfaction, and drive for thinness in anorexia nervosa

BACKGROUND

Body size overestimation is a fundamental feature in anorexia nervosa (AN). There have been inconclusive findings about the extent to which this feature distinguishes psychopathology and some authors have argued that overestimation may be a function of lower body mass index (BMI).

METHODS

We examine body size estimation accuracy and body dissatisfaction in 74 females with AN and 11 age-matched female controls using two well-established psychophysical procedures.

RESULTS

Participants with AN overestimated their body size more and had greater body dissatisfaction than controls. Size accuracy was found to be independent of BMI and correlated with body dissatisfaction and drive for thinness in participants with AN.

CONCLUSIONS

We conclude that overestimation of body size in AN is related to the psychopathology associated with the disorder and is not due to any perceptual tendency for people with lower BMI to overestimate their body size. We discuss the implications of these findings for treatment of AN.

The influence of personal BMI on body size estimations and sensitivity to body size change in anorexia spectrum disorders

In this cross-sectional study, we investigated the influence of personal BMI on body size estimation in 42 women who have symptoms of anorexia (referred to henceforth as anorexia spectrum disorders, ANSD), and 100 healthy controls. Low BMI control participants over-estimate their size and high BMI controls under-estimate, a pattern which is predicted by a perceptual phenomenon called contraction bias. In addition, control participants' sensitivity to size change declines as their BMI increases as predicted by Weber's law. The responses of women with ANSD are very different. Low BMI participants who have ANSD are extremely accurate at estimating body size and are very sensitive to changes in body size in this BMI range. However, as BMI rises in the ANSD participant group, there is a rapid increase in over-estimation concurrent with a rapid decline in sensitivity to size change. We discuss the results in the context of signal detection theory.

Memory versus perception of body size in patients with anorexia nervosa and healthy controls

The objective of this study was to compare body size estimation based on memory versus perception, in patients with anorexia nervosa (AN) and healthy controls, adjusting for possible confounders. Seventy-one women (AN: 37, controls: 35), aged 14-29 years, were assessed with a computerized body size estimation morphing program. Information was gathered on depression, anxiety, time since last meal, weight and height. Results showed that patients overestimated their body size significantly more than controls, both in the memory and perception condition. Further, patients overestimated their body size significantly more when estimation was based on perception than memory. When controlling for anxiety, the difference between patients and controls no longer reached significance. None of the other confounders contributed significantly to the model. The results suggest that anxiety plays a role in overestimation of body size in AN. This finding might inform treatment, suggesting that more focus should be aimed at the underlying anxiety.

Body size over-estimation in women with anorexia nervosa is not qualitatively different from female controls

Over-estimation of body size is a cardinal feature of anorexia nervosa (AN), usually revealed by comparing individuals who have AN with non-AN individuals, the inference being that over-estimation is pathological. We show that the same result can be reproduced by sampling selectively from a single distribution of performance in body size judgement by comparing low BMI individuals with normal BMI individuals. Over-estimation of body size in AN is not necessarily pathological and can be predicted by normal psychophysical biases in magnitude estimation. We confirm this prediction in a dataset from a morphing study in which 30 women with AN and 137 control women altered a photograph of themselves to estimate their actual body size. We further investigated the relative contributions of sensory and attitudinal factors to body-size overestimation in a sample of 166 women. Our results suggest that both factors play a role, but their relative importance is task dependent.

Reconceptualizing second-person interaction

Over the last couple of decades, most neuroscientific research on social cognition has been dominated by a third-person paradigm in which participating subjects are not actively engaging with other agents but merely observe them. Recently this paradigm has been challenged by researchers who promote a second-person approach to social cognition, and emphasize the importance of dynamic, real-time interactions with others. The present article's contribution to this debate is twofold. First, we critically analyze the second-person challenge to social neuroscience, and assess the various ways in which the distinction between second- versus third-person modes of social cognition has been articulated. Second, we put forward an alternative conceptualization of this distinction-one that gives pride of place to the notion of reciprocity. We discuss the implications of our proposal for neuroscientific studies on social cognition.

Mental body distance comparison: a tool for assessing clinical disturbances in visual body image

Despite numerous body size estimation studies, it cannot be concluded that the disturbance of body image in anorexia nervosa (AN) is specifically one of the visual body images. We adopted a visual imagery method, the Distance Comparison task, to enable across-population testing of differences in visual body image with respect to shape. Participants were asked to mentally scan across two body widths (e.g. hips and shoulders) and to decide as quickly as possible which one was longer or shorter. If the mental representation accessed to make such comparisons is visual, an inverse relation would be expected between RT and distance difference on the body to be judged (i.e. actual difference in size between the two body widths), with accuracy increasing with increasing distance difference. Females with high body shape concern (scoring high on the Body Shape Questionnaire: BSQ, n=23) were compared to females with low body shape concern (scoring low on the BSQ, n=19). RT and distance differences on the body demonstrated standard distance differences effects: RT increased and accuracy decreased with decreasing distance differences on the body. Groups differed with respect to accuracy, in that females high on body shape concern were significantly less accurate than females low on body shape concern when making evaluations involving small (9cm) differences, which implies a less appropriate visual image of the own body in the former group. With respect to the relation between RT and body distance difference, on the other hand, there were no differences between groups. We concluded that evaluations of own body size employ visual imagery and that the distance comparison task holds promise for the assessment of visual disturbances in body image in clinical populations.

Body Image Assessment Software: psychometric data

The aim of the present study was to analyze the psychometric characteristics of the Body Image Assessment Software (BIAS), an innovative interactive computer program developed to assess body image disturbances. The program was tested on 252 psychology students at the University of Barcelona and 51 patients with an eating disorder (ED). The subjects filled in the Eating Attitudes Test-26, the Body Shape Questionnaire, the body dissatisfaction scale of the Eating Disorders Inventory-2, and the Body Image Assessment-Revised (a test of silhouettes). Results showed good validity and very high reliability. Furthermore, BIAS was able to discriminate between people who were at risk of an ED and those who were not, as well as between people with and without a history of an ED. Those at risk of having an ED and those with a current ED showed more body image distortion (overestimation of body size) and higher levels of body image dissatisfaction.

The rubber hand illusion: Sensitivity and reference frame for body ownership

When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed 'Rubber Hand Illusion' (RHI). We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the two hands. We created the mismatch either by adjusting stimulation or posture of the subject's hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject's hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject's hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject's hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject's hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual-tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is 'me' is interpreted with respect to a prior mental body representation.

Accuracy of body size estimation: Role of biopsychosocial variables

This study evaluated factors related to the perceptual disturbances of body image. Using a digital body image computer program, 191 participants (107 women, 82 men) adjusted an image of their body to the perceived actual size at five body regions; chest, waist, hips, thighs and calves. A neutral object (a vase) was also adjusted to partial out the level of perceptual distortion present with a neutral object. Men and women overestimated the size of the neutral object and their body image. Among women, overestimation was primarily predicted by high levels of depression, and media and peer influences to be thinner and increase muscles. Among men, overestimation was predicted by high BMI, media influences to lose weight and increase muscles, and peer influences to increase muscles. These findings suggest that perceptual accuracy of body image is primarily predicted by biopsychosocial influences.

Anorexia nervosa in male adolescents: body image, eating attitudes and psychological traits

PURPOSE

To evaluate body image and its relationship with psychological and behavioral traits associated with anorexia nervosa in male patients.

METHODS

Thirty male adolescents with anorexia nervosa (AN) were compared with 421 male adolescents from the general population. Body image was evaluated with the Subjective Body Dimensions Apparatus. Eating attitudes were evaluated by the Eating Attitudes Test in its 26-item version (EAT-26). In 19 AN patients and 200 boys from the comparison group, the Eating Disorders Inventory (EDI) was also administered.

RESULTS

AN patients had higher mean scores in the EAT-26 and the Body Dissatisfaction scale on the EDI, but not on the other EDI scales. Both groups overestimated all parts of their bodies but AN patients presented a greater overestimation of shoulders (p = .007), hips (p = .01) and thighs (p = .019). Correlations in the anorexic group were high and negative between body overestimation and body mass index and also high but positive between overestimation and the EAT and the Drive for Thinness scale on the EDI. Overestimation did not correlate significantly with other EDI scales.

CONCLUSIONS

Male patients with anorexia nervosa overestimate some parts of their bodies more often than controls; this overestimation is related to body mass index, abnormal eating attitudes and drive for thinness, but not to other psychological traits evaluated by the EDI.

Amputees by choice: body integrity identity disorder and the ethics of amputation

Should surgeons be permitted to amputate healthy limbs if patients request such operations? We argue that if such patients are experiencing significant distress as a consequence of the rare psychological disorder named Body Integrity Identity Disorder (BIID), such operations might be permissible. We examine rival accounts of the origins of the desire for healthy limb amputations and argue that none are as plausible as the BIID hypothesis. We then turn to the moral arguments against such operations, and argue that on the evidence available, none is compelling. BIID sufferers meet reasonable standards for rationality and autonomy: so as long as no other effective treatment for their disorder is available, surgeons ought to be allowed to accede to their requests.

Body size estimation: testing a new mirror-based assessment method

OBJECTIVE

The aim of the current study was to compare a new ecologically valid method of body size estimation with an existing, commonly used method.

METHOD

The new method uses a "mirror-sized" image and measures perception rather than memory of body size. Fifty-five healthy women participated in the study.

RESULTS

Body size estimations with the new method were significantly larger than with the existing method (p <.001). This difference was specific to body size and was not seen for estimation of neutral images.

DISCUSSION

The results of the study show that different body size estimations are made with the new more ecologically valid method compared with the existing method. This finding has important implications for research into the factors influencing the perception of body size.

A new ecologically valid method to assess body size estimation and body size dissatisfaction

OBJECTIVE

The primary aim of the present study was to develop an ecologically valid method for assessing the perception of body size (as opposed to the memory of body size).

METHOD

Women with clinical eating disorders (N = 14) and no eating disorder (N = 24) estimated their actual and desired body size while looking in a mirror. Estimations were made using projected images that were the same height as the participants' reflections in the mirror.

RESULTS

This new method assessed the perception of body size under conditions that resembled the real-life situation of viewing oneself in a mirror. Participants with eating disorders significantly overestimated their body size relative to controls (p <.05) and tended to be more dissatisfied with their body size (p =.07).

DISCUSSION

It is argued that the new method assesses the perception of body size, is ecologically valid, and is the most clinically relevant of the methods developed to date.

Body image of sexually and physically abused children

Body size perception was measured in 41 children aged 6-10 who had been either sexually or physically abused, or had no history of abuse. Two psychophysical methods were used, including the staircase method and a signal detection method. In the staircase methodology, children adjusted the direction of distortion of their continuously changing body size. In the signal detection method, children made judgments about the presence or absence of size distortion in presented images. Results using the staircase method indicated children overestimated their body sizes, with no differences between abuse conditions, gender, or age. For the signal detection methodology, no difference in ability to detect the presence/absence of size distortion (d') was found between abuse conditions, although females were less accurate than males. All groups were better able to detect distortion when the image was distorted too wide. Measures of response bias (Ln beta) indicated that sexually abused children had a greater bias to report size distortion as present, as compared with the physically abused children.

Predictors of eating disorder scores in children ages 6 through 14: a longitudinal study

The objective of this study was to identify variables that predict higher eating disorder scores in non-clinical boys and girls ages 6 through 14. Two hundred sixteen children participated and were tested annually for 3 years. A TV-video procedure was used to measure the accuracy of body size judgments. Variables examined included demographic, familial, sociocultural, social, esteem, and clinical variables. Predictors of higher eating disorder scores for both sexes included height and weight, children's perceptions of parental concerns about their body size, low body esteem, and depression. For girls only, a larger perceived body size and smaller idealized body size were also predictors. Teasing was a predictor for boys only. An analysis of longitudinal changes suggests that low body esteem becomes a significant factor around age 9, depression emerges as a predictor at age 10, and body size judgments in perceived and ideal sizes at ages 11 and 12. Changes over 2 years in individuals' weight and height, teasing, body dissatisfaction, and eating disorder scores were also found to predict higher eating disorder scores.

Body size perception in anorexia nervosa: a signal detection approach

This study investigated whether individuals with anorexia nervosa (AN) visualize themselves as fatter than they are because they perceive themselves as fatter. Females with AN who overestimated their own body size judged size differences between pictures of their own body, and then again of someone else's body. Signal detection analysis of the results showed no differences in perceptual sensitivity between the AN and normal and thin control groups. No significant correlations were found between body size estimates and perceptual sensitivity. The anorexic group did, however, show a bias to report seeing "thin" differences, which was opposite to that of thin controls. Because bias differences between the groups were significant while sensitivity differences were not, it was concluded that abnormalities of body image most probably arise during reconstruction of the visual body image, rather than during perception of the body.

Body image disturbances and their change with videofeedback in anorexia nervosa

Disturbance in the way the body is experienced is a diagnostic criterion for anorexia nervosa, and impedes recovery. A method relatively free of external prompts, to reduce the potential for experimentally induced biases, evaluated body image distortions (BID) in 18 patients with anorexia nervosa soon after admission to an inpatient unit, and 18 normal controls, before and after a videofeedback session. The BID were assessed in the affective and self/social domains by visual analogue scales in which the instructional set oriented subjects to (a) the sensation of fatness (Affective Response, AR), and (b) size compared with other young women (Comparative Size Response, CSR). The AR and CSR were significantly greater than normal in anorexia but decreased significantly with videofeedback, while values for controls were stable. The AR and CSR were only partially independent, indicating overlap of the domains. In anorexia only, the responses were related to two DSM-IV diagnostic criteria for anorexia, fear of gaining weight and health-weight concerns, as well as to drive for thinness and body dissatisfaction. Fear of gaining weight occupied a central position in determining the magnitudes of BID and the other measures, including anxiety and depression.

The earliest sense of self and others: Merleau-Ponty and recent developmental studies

Recent studies in developmental psychology have found evidence to suggest that there exists an innate system that accounts for the possibilities of early infant imitation and the existence of phantom limbs in cases of congenital absence of limbs. These results challenge traditional assumptions about the status and development of the body schema and body image, and about the nature of the translation process between perceptual experience and motor ability. Merleau-Ponty, who was greatly influenced by his study of developmental psychology, and whose phenomenology of perception was closely tied to the concept of the body schema, accepted these traditional assumptions. They also informed his philosophical conclusions concerning the experience of self and others. We re-examine issues involved in understanding self and others in light of the more recent research in developmental psychology. More specifically our re-examination challenges a number of Merleau-Ponty's conclusions and suggests, in contrast, that the newborn infant is capable of a rudimentary differentiation between self and non-self.

Body size estimation in eating disorder patients: testing the video distortion method on a life-size screen

The video distortion method on a life-size screen is a new method for studying eating disordered patients' estimations of their own body width. Testing this method in female patients (53 with anorexia nervosa, 38 with bulimia nervosa) and 36 normal females, yielded high to very high reliability scores (consistency and test-retest stability). A careful analysis of the 'just noticeable difference' showed that a 5% deviation from the undistorted image should be considered as within the range of accuracy. Taking this into account, anorectic patients appear to score below, above, as well as within the normal range. Bulimia nervosa patients are either accurate in their body estimations or overestimate their body width. All control Ss are correct in their estimations. With this method no significant differences were found between the anorectic patients and the controls. Bulimics differ significantly from anorectics and controls on their optative responses (i.e. what they wanted to look like) and their affective responses (i.e. what they felt they looked like).

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.