Body size estimation in anorexia nervosa: a brief review of findings from 2003 through 2013

The psychological factors mediating/moderating the association between body-image disturbance and depression: A systematic review

Available evidence demonstrates that individuals with body-image disturbance (BID) are prone to suffer from depression. This systematic review provides, to our knowledge, the first synthesis of the psychological mechanism of the association between BID and depression. We conducted a thorough search of online databases, including PubMed, Web of Science, and PsycINFO, for articles published up until February 2024. The final analysis comprised a total of 23 studies that focused on the mediating or moderating effects of psychological factors between depression and BID. This review identifies self-esteem and social support as both mediators and moderators of the relationship between BID and depression, while perceived stress acted only as a mediator. High self-esteem and strong social support as well as low levels of perceived stress may help individuals experience lower levels of BID, thereby contributing to a decreased likelihood of depression. Interventions aimed at increasing self-esteem, developing strong support, and decreasing perceived stress may hold promise to reduce the risk of depression in those with BID.

Embodiment of underweight and normal-weight avatars affects bodily self-representations in anorexia nervosa

Body image distortion (BID) is a crucial aspect of anorexia nervosa (AN), leading to body overestimation, dissatisfaction, and low self-esteem. BID significantly influences the onset, maintenance, and relapse of the pathology. We assessed whether a Full Body Illusion (FBI) using under and normal-weight avatars' bodies affects perceptual body image and body schema estimations in both individuals with anorexia nervosa (AN) and healthy controls (HC). After each embodiment procedure, we asked participants to estimate the width of their hips (Perceptual Body Image Task) and the minimum aperture width of a virtual door necessary to pass through it (Body Schema Task). Additionally, we asked participants to rate the avatars in terms of self-similarity, attractiveness, and implicit disgust (i.e., pleasant/unpleasant body odour). Whereas participants with AN (N = 26) showed changes in body schema estimations after embodying the normal-weight avatar, no changes were found in HC (N = 25), highlighting increased bodily self-plasticity in AN. Notably, individuals with AN rated the normal weight avatar as the most similar to their real body, which was also considered the least attractive and the most repulsive. These ratings correlated with BID severity. Furthermore, at the explicit level, all participants reported feeling thinner than usual after embodying the underweight avatar. Overall, our findings suggest that BID in AN engages multiple sensory channels (from visual to olfactory) and components (from perceptual to affective), offering potential targets for innovative non-invasive treatments aimed at modifying flexible aspects of body representation.

Unlocking the potential of 'passive' modulation: How sensory stimulation shapes hand and face size

Knowledge of the body size is intricately tied to multisensory integration processes that rely on the dynamic interplay of top-down and bottom-up mechanisms. Recent years have seen the development of passive sensory stimulation protocols aimed at investigating the modulation of various cognitive functions, primarily inducing perceptual learning and behaviour change without the need for extensive training. Given that reductions in sensory input have been associated with alterations in body size perception, it is reasonable to hypothesize that increasing sensory information through passive sensory stimulation could similarly influence the perception of the size of body parts. The primary aim of this study was to investigate the potential modulatory effects of passive sensory stimulation on the perception of hand and face size in a group of young adults. Passive sensory stimulation effectively modulated the size representation of the stimulated hand, supporting the notion that access to somatosensory and proprioceptive information is prioritised for the hands but may not extend to the face. Increased somatosensory input resulted in a reduction of distortion, providing evidence for bottom-up modulation of size representation. Passive sensory stimulation can induce subjective changes in body size perception without the need for extensive training. This paradigm holds promise as a potential alternative for modulating distorted size representation in individuals with body representational deficits.

Testing the validity of online psychophysical measurement of body image perception

This body image study tests the viability of transferring a complex psychophysical paradigm from a controlled in-person laboratory task to an online environment. 172 female participants made online judgements about their own body size when viewing images of computer-generated female bodies presented in either in front-view or at 45-degrees in a method of adjustment (MOA) paradigm. The results of these judgements were then compared to the results of two laboratory-based studies (with 96 and 40 female participants respectively) to establish three key findings. Firstly, the results show that the accuracy of online and in-lab estimates of body size are comparable, secondly that the same patterns of visual biases in judgements are shown both in-lab and online, and thirdly online data shows the same view-orientation advantage in accuracy in body size judgements as the laboratory studies. Thus, this study suggests that that online sampling potentially represents a rapid and accurate way of collecting reliable complex behavioural and perceptual data from a more diverse range of participants than is normally sampled in laboratory-based studies. It also offers the potential for designing stratified sampling strategies to construct a truly representative sample of a target population.

The impact of weight and negative body image on the body schema in undergraduate women

BACKGROUND AND OBJECTIVES

Alterations of the sensory-motor body schema question the origins of such distortions. For example, in anorexia nervosa where patients think they are broader than they really are (body image) but act as if it was really the case (body schema). To date, the results of studies about what hinders the updating of the body schema so much (weight, body image) have been contradictory.

METHODS

We therefore conducted two studies that aimed to assess the impact of weight and body image problems on body schema in 92 young women without anorexia nervosa. For this purpose, we used a new body schema assessment tool (SKIN) that is sensitive enough to detect fine alterations of body schema in seven different body parts.

RESULTS

In Study 1, the thinness or overweight of the young women had a major impact on their tactile perception, especially because the assessed body part was a sensitive area for body dissatisfaction in young women (e.g., belly, thigh). In Study 2, the level of body dissatisfaction of the participants in its attitudinal and perceptual dimension also had a negative impact on their body schema, again in interaction with weight and body part.

CONCLUSIONS

These results imply that body dissatisfaction and thinness are predictors of massive body schema distortions. An oversized body schema could maintain various weight-control behaviors, thus risking the development, maintenance, or relapse of an eating disorder.

Perceptual Dysfunction in Eating Disorders

Eating disorders (EDs) are characterized by abnormal responses to food and weight-related stimuli and are associated with significant distress, impairment, and poor outcomes. Because many of the cardinal symptoms of EDs involve disturbances in perception of one's body or abnormal affective or cognitive reactions to food intake and how that affects one's size, there has been longstanding interest in characterizing alterations in sensory perception among differing ED diagnostic groups. Within the current review, we aimed to critically assess the existing research on exteroceptive and interoceptive perception and how sensory perception may influence ED behavior. Overall, existing research is most consistent regarding alterations in taste, visual, tactile, and gastric-specific interoceptive processing in EDs, with emerging work indicating elevated respiratory and cardiovascular sensitivity. However, this work is far from conclusive, with most studies unable to speak to the precise etiology of observed perceptual differences in these domains and disentangle these effects from affective and cognitive processes observed within EDs. Further, existing knowledge regarding perceptual disturbances in EDs is limited by heterogeneity in methodology, lack of multimodal assessment protocols, and inconsistent attention to different ED diagnoses. We propose several new avenues for improving neurobiology-informed research on sensory processing to generate actionable knowledge that can inform the development of innovative interventions for these serious disorders.

Understanding and treating body image disturbances in eating disorders through body illusion interventions: a scoping review protocol

BACKGROUND

We plan a scoping review aimed to synthesize what is known about the use of sensory-driven body illusion (BI) interventions for understanding and treating body image disturbance (BID) in people diagnosed with clinical eating disorders (EDs) and people with subclinical ED symptomatology. Our study will provide an outline of the current literature, identify gaps within the literature, and suggest novel directions for future research.

METHODS/DESIGN

The scoping review process will be guided by the methodological framework of Arksey and O'Malley, subsequent recommendations by Levac et al., and the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols Extension for Scoping Reviews guidelines. The following electronic databases will be systematically searched: MEDLINE (via PubMed), Web of Science, PsycINFO, and Scopus. Furthermore, to identify additional studies, we will use a search engine such as Google Scholar, and for grey literature, we will include Proquest for Dissertations and Theses. A search strategy has been identified and agreed upon by the research team in conjunction with a research librarian. Two researchers will screen the titles and abstracts independently and then assess the full text of the selected citations for the inclusion criteria. A third reviewer will be involved in cases of disagreement. Data will be extracted, collated, and charted to summarize all the relevant methods, outcomes, and key findings in the articles.

DISCUSSION

A better understanding of this topic will aid in the development and refinement of current treatments aimed at treating BID in people with EDs. Implications and recommendations for research, policy, and practice in the context of the ED community will be discussed.

SYSTEMATIC REVIEW REGISTRATION

https://osf.io/3bcm6/?view_only=83b2e8a2445d4266909992e3dfb51929.

A conceptual framework on body representations and their relevance for mental disorders

Many mental disorders are accompanied by distortions in the way the own body is perceived and represented (e.g., eating disorders, body dysmorphic disorder including muscle dysmorphia, or body integrity dysphoria). We are interested in the way these distortions develop and aim at better understanding their role in mental health across the lifespan. For this purpose, we first propose a conceptual framework of body representation that defines this construct and integrates different perspectives (e.g., cognitive neuroscience, clinical psychology) on body representations. The framework consists of a structural and a process model of body representation emphasizing different goals: the structural model aims to support researchers from different disciplines to structure results from studies and help collectively accumulate knowledge about body representations and their role in mental disorders. The process model is reflecting the dynamics during the information processing of body-related stimuli. It aims to serve as a motor for (experimental) study development on how distorted body representations emerge and might be changed. Second, we use this framework to review the normative development of body representations as well as the development of mental disorders that relate to body representations with the aim to further clarify the potential transdiagnostic role of body representations.

Accuracy of estimating self and other body size among adolescent girls with anorexia nervosa

This study aimed to analyze body size estimates of others by patients with anorexia nervosa (AN) and to identify any differences with the perception of their own body size. Adolescent females (age, 13-17 years) were enrolled into AN (n = 30) and control(n = 23) groups. The Subjective Body Dimensions Apparatus (SBDA) was used to evaluate body size estimates for oneself (self-estimation) and others (other-estimation). Participants also completed questionnaires assessing eating disorders and depressive symptoms. The AN and control groups scored significantly higher in self-estimation than in other-estimation. However, the AN group showed higher self-estimation scores than the control group for all the body parts and for the global silhouette (p < .001). Patients with more severe eating disorder symptomatology showed more distorted self-estimation (p < .05). No statistically significant differences were found in the other-estimation scores between the groups (p = .714), indicating that AN and control patients estimate the body sizes of others similarly. Eating disorder symptomatology correlates with self-estimation scores but not with other-estimation scores in adolescents with AN. No correlations existed between clinical symptomatology and other-estimation.

Measuring implicit associations between food and body stimuli in anorexia nervosa: a Go/No-Go Association Task

PURPOSE

The present study aimed to explore the implicit associations between food and bodily stimuli in patients with anorexia nervosa (AN) and control subjects (HC).

METHODS

A Go/No-Go Association Task was administrated to 55 participants (28 AN and 27 HC), using food stimuli (low-calorie food vs. high-calorie food) and body stimuli (underweight vs. overweight bodies).

RESULTS

We evidenced an implicit association between food and body stimuli in the AN group, whereas the HC group only showed a tendency. AN and HC groups also exhibited different categorization strategies: the AN group tended to categorize stimuli as low-calorie foods and underweight bodies less than the HC group, and they tended to categorize stimuli as high-calorie foods and overweight bodies more than the HC group.

CONCLUSION

The present study revealed for the first time specificities of the AN population's implicit association between food and body stimuli in terms of association strength and categorization strategy. Furthermore, the results suggest that combining implicit methodologies with other methods could contribute to a better characterization of the physiopathology of AN.

LEVEL OF EVIDENCE

Level I, experimental study.

The impact of floatation therapy on body image and anxiety in anorexia nervosa: a randomised clinical efficacy trial

Background

Body image disturbance and anxiety are core features of anorexia nervosa (AN), a psychiatric disorder with one of the highest mortality rates. This study examined the efficacy of a novel non-pharmacological treatment, floatation-REST (Reduced Environmental Stimulation Therapy) on body image disturbance and anxiety in inpatients with AN.

Methods

This parallel group randomised controlled trial compared floatation-REST vs. care as usual in women and girls hospitalised for treatment of AN in Tulsa, Oklahoma, USA. Participants were randomised on a 2:1 ratio to receive eight, twice-weekly, 60-min floatation-REST sessions for 4 weeks, in addition to care as usual, or to receive care as usual. The primary outcome was the average change in body dissatisfaction from pre- to post-float as measured by the Photographic Figure Rating Scale. The secondary outcome was the average change in anxiety from pre- to post-float as measured by the state version of the State Trait Anxiety Inventory. Longitudinal effects of floatation-REST on body dissatisfaction were also examined. All analyses were conducted using the intention-to-treat principle. Planned linear mixed models tested the effect of floatation-REST vs. care as usual. The trial was preregistered (clinicaltrials.govNCT03610451).

Findings

Between March 16, 2018 and February 25, 2021, 133 participants were screened for eligibility, and 86 were consented. Eighteen were excluded after consent, for a final randomisation sample of 68 participants (45 floatation-REST; 23 care as usual). There were two session by condition interactions on body dissatisfaction (p = 0.00026) and state anxiety (p < 0.0001), such that the floatation-REST group exhibited acute (i.e., pre- to post-session) reductions in body dissatisfaction (floatation-REST group mean change (Δm) = -0.43; 95% CI -0.56 to -0.30, p < 0.0001, Cohen's d = 0.23), and acute reductions in anxiety (floatation-REST group Δm = -15.75; 95% CI -17.95 to -13.56, p < 0.0001, Cohen's d = 1.52); however, the care as usual group exhibited no significant changes. With regard to longitudinal results, there was a significant time by treatment interaction between baseline and immediately post intervention (p = 0.012) and baseline and six-month follow up (p = 0.0019). At immediately post intervention, there was a trending reduction in body dissatisfaction for the floatation-REST group (Δm = -0.41, 95% CI -0.86 to 0.03, p = 0.068) and care as usual group (Δm = 0.61; 95% CI -0.04 to 1.27, p = 0.070). At six-months post-intervention, the floatation-REST group exhibited lower body dissatisfaction (Δm = -0.91; 95% CI -1.37 to -0.45, p = 0.0020, Cohen's d = 0.53) whereas the care as usual group reported no change in body dissatisfaction (Δm = 0.35; 95% CI -0.28 to 0.98, p = 0.96) relative to baseline. There were no adverse events related to the trial during the study.

Interpretation

Our findings suggest that Floatation-REST decreased body dissatisfaction compared to care as usual acutely after each float session and at six-month follow-up. Floatation-REST has potential utility for the treatment of body image disturbance and anxiety in AN. These results may be limited by some generalisability concerns given the recruitment of a modest sample receiving inpatient treatment at a single site.

Funding

The William K. Warren Foundation.

Mental health meets computational neuroscience: A predictive Bayesian account of the relationship between interoception and multisensory bodily illusions in anorexia nervosa

Mental health disorders pose a significant challenge to society. The Bayesian perspective on the mind offers unique insights and tools that may help address a variety of mental health conditions. Psychopathological dysfunctions are often connected to altered predictive and active inference processes, in which cognitive and physiological pathogenic beliefs shape the clinical condition and its symptoms. However, there is a lack of general empirical models that integrate cognitive beliefs, physiological experience, and symptoms in healthy and clinical populations. In this study, we examined the relationship between altered predictive mechanisms, interoception, and pathological bodily distortions in healty individuals and in individuals suffering from anorexia nervosa (AN). AN patients (N=15) completed a Virtual Reality Full-Body Illusion along with interoceptive tasks twice: at hospital admission during an acute symptomatological phase (Time 1) and after a 12-week outpatient clinical weight-restoring rehabilitative program (Time 2). Results were compared to a healthy control group. Our findings indicated that higher levels of interoceptive metacognitive awareness were associated with a greater embodiment. However, unlike in healthy participants, AN patients' interoceptive metacognition was linked to embodiment even in multisensory mismatching (asynchronous) conditions. In addition, unlike in healthy participants, higher interoceptive metacognition in AN patients was related to prior abnormal bodily distortions during the acute symptomatology phase. Prediction errors in bodily estimates predicted posterior bodily estimate distortions after the illusion, but while this relationship was only significant in the synchronous condition in healthy participants, there was no significant difference between synchronous and asynchronous conditions in AN patients. Despite the success of the rehabilitation program in restoring some dysfunctional patterns in the AN group, prediction errors and posterior estimate distortions were present at hospital discharge. Our findings suggest that individuals with AN prioritize interoceptive metacognitive processes (i.e., confidence in their own perceived sensations rather than their actual perceptions), disregarding bottom-up bodily inputs in favour of their prior altered top-down beliefs. Moreover, even if the rehabilitative program partially mitigated these alterations, the pathological condition impaired the patients' ability to coherently update their prior erroneous expectations with real-time multisensory bottom-up bodily information, possibly locking the patients in the experience of a distorted prior top-down belief. These results suggest new therapeutic perspectives and introduce the framework of regenerative virtual therapy (RVT), which aims at utilizing technology-based somatic modification techniques to restructure the maladaptive priors underlying a pathological condition.

Bodily self-recognition and body size overestimation in restrictive anorexia nervosa: implicit and explicit mechanisms

It is widely known that among others, a pervasive symptom characterizing anorexia nervosa (AN) concerns body image overestimation, which largely contributes to the onset and maintenance of eating disorders. In the present study, we investigated the nature of the body image distortion by recording accuracy and reaction times in both a group of healthy controls and AN patients during two validated tasks requiring an implicit or explicit recognition of self/other hand stimuli, in which the perceived size of the stimuli was manipulated. Our results showed that (1) the perceived size of hand stimuli modulated both the implicit and explicit processing of body parts in both groups; (2) the implicit self-advantage emerged in both groups, but the bodily self, at an explicit level (perceptual, psycho-affective, cognitive) together with the integration and the distinction between self and other, was altered only in restrictive anorexia patients. Although further investigations will be necessary, these findings shed new light on the relationship between the different layers of self-experience and bodily self-disorders.

Relating different Dimensions of Bodily Experiences: Review and proposition of an integrative model relying on phenomenology, predictive brain and neuroscience of the self

How we mentally experience our body has been studied in a variety research domains. Each of these domains focuses in its own ways on different aspects of the body, namely the neurophysiological, perceptual, affective or social components, and proposes different conceptual taxonomies. It is therefore difficult to find one's way through this vast literature and to grasp the relationships between the different dimensions of bodily experiences. In this narrative review, we summarize the existing research directions and present their limits. We propose an integrative framework, grounded in studies on phenomenal consciousness, self-consciousness and bodily self-consciousness, that can provide a common basis for evaluating findings on different dimensions of bodily experiences. We review the putative mechanisms, relying on predictive processes, and neural substrates that support this model. We discuss how this model enables a conceptual assessment of the interrelationships between multiple dimensions of bodily experiences and potentiate interdisciplinary approaches.

Risk of eating disorders and the relationship with interest in modern culture among young female students in a university in Bangladesh: a cross-sectional study

BACKGROUND

Eating disorders (EDs) emerge most often in adolescent girls. While the basic neural and psychiatric mechanisms of ED development remain unknown, their incidence has increased with sociocultural modernization. To determine what aspects of modern culture are related to EDs, we examined the relationship between predisposition to EDs and interest in several modern cultural factors among young female university students in Bangladesh.

METHODS

A cross-sectional study was conducted in a population of 196 female students aged 18-29 years in a university in Bangladesh. Their predisposition to EDs was examined using the Eating Attitudes Test-26 (EAT-26), and their interest in modern culture was evaluated by grading interest in fashionable clothes, Indian TV shows/serials, luxury food and social network activities, and by examining involvement in cultural activities such as playing, dancing, parties and singing. The relationship between predisposition to EDs and interest in modern culture was then examined. The relation between EAT-26 score and body mass index (BMI) was also examined.

RESULTS

The EAT-26 revealed that 37% of the participants were at risk of developing an ED. Correlation analyses showed that a high EAT-26 score was correlated with a high interest in fashionable clothes and Indian TV shows/serials, but not with a high interest in luxury food or social network activities, or involvement in cultural activities, such as playing, dancing, parties and singing. Further, EAT-26 questions in the dieting category and oral control category, but not the bulimia and food preoccupation category, were correlated with interest in cultural factors. EAT-26 score showed no significant correlation with BMI.

CONCLUSIONS

The results of this study indicate that the risk of EDs is related to an interest in several facets of modern culture. Monitoring the cultural interests of adolescent females, who are continually exposed to modern culture and highly susceptible to EDs, will contribute to the prevention of EDs.

Body image distortion among Brazilian and Portuguese women with children: A comparative study between the ELSA-Brasil and Generation XXI cohorts

Solid evidence indicates that body image distortion is associated with various physical and mental health problems in women (e.g. Lee and Lee, 2016; Mölbert et al., 2017; Raj and Ploriya, 2020; Sagar, 2005; Shin et al., 2015). Furthermore, body image has been shown to vary according to life context and stage, particularly after a woman has had children. This scenario justifies the comparison between different countries and cultures. The objective of the present study was to evaluate the prevalence and associated factors of body image distortion/accuracy in Brazilian and Portuguese women with children. The study assessed women selected from two epidemiological cohorts: ELSA-Brasil in Brazil (n = 1468) and Generation XXI in Portugal (n = 3380). The data analyzed were based on multidimensional questionnaires from which sociodemographic and family characteristics as well as data associated with lifestyle and health were obtained. The results show that most women in both cohorts had an accurate perception of their own body size. In cases of distorted self-perception, the likelihood of the Brazilian women perceiving themselves as being heavier was greater if they had had cancer, whereas the Portuguese women were less likely to perceive themselves as heavier when they had less schooling. Perceiving themselves as thinner than they actually are, was associated with poorer self-perception of their own state of health in the Brazilian women and with poorer schooling in both the Brazilian and Portuguese women. The present findings contribute towards improving understanding of the influence of body image distortion on the health and wellbeing of Brazilian and Portuguese women, possibly leading to the implementation of health-promoting policies in both countries.

What happens in the course of positive mirror exposure? Effects on eating pathology, body satisfaction, affect, and subjective physiological arousal in patients with anorexia and bulimia nervosa

OBJECTIVE

Mirror exposure (ME) is a therapeutic technique to improve body image disturbance. However, evidence on the effectiveness of different forms of ME in clinical populations is lacking. The present study therefore analysed effects of ME on trait-like and state measures of body image in patients with anorexia nervosa (AN) and bulimia nervosa (BN).

METHOD

The present study therefore analysed effects of ME on trait-like and state measures of body image in patients with anorexia nervosa (AN) and bulimia nervosa (BN). In total, 47 inpatients underwent 3 ME sessions guided by a therapist, with instructions to exclusively verbalise positively about their whole body. Participants completed questionnaires on trait-like eating pathology and body image at the start and end of the study, and instruments on state affect and body satisfaction were administered directly before and after each ME session. Subjective physiological arousal and emotional valence relating to each body part were assessed within each session.

RESULTS

The results indicate significant improvements in eating pathology and body image regarding trait-like measures in patients with AN and BN. Concerning state measures, negative affect significantly decreased and body satisfaction increased during ME. Physiological arousal decreased and positively valenced emotions relating to the various body parts increased.

CONCLUSIONS

These findings suggest that positively verbalising about one's body during ME improves eating pathology, body image, affect, and subjective physiological arousal, and thus seems to be an effective form of ME.

Changes in the perceived size of the body following exposure to distorted self-body images

Inaccurate perceptions, such as under- or over-estimation of body size are often found in clinical eating disorder populations but have recently been shown also in healthy people. However, it is not yet clear how body size perception may be affected when the internal body representation is manipulated. In this study, visual adaptation was used to investigate whether exposure to distorted visual feedback alters the representation of body size and how long any such effects might last. Participants were exposed for five minutes to a distorted life-size image of themselves that was either 20% wider or 20% narrower than their normal size. Accuracy was measured using our novel psychophysical method that taps into the implicit body representation. The accuracy of the representation was assessed at 6, 12 and 18 min following exposure to adaptation. Altered visual feedback caused changes in participants' judgements of their body size: adapting to a wider body resulted in size overestimation whereas underestimations occurred after adapting to a narrower body. These distortions lasted throughout testing and did not fully return back to normal within 18 min. The results are discussed in terms of the emerging literature indicating that the internal representation of the body is dynamic and flexible.

Visualizing Emotional Arousal within the Context of Body Size Evaluation: A Pilot Study of Steady-State Visual Evoked Potentials in Women with Anorexia Nervosa and Healthy Controls

Maladaptive body size evaluation processes and body dissatisfaction are known as central risk factors for the development and maintenance of anorexia nervosa (AN). This study aimed to experimentally test potential key facets, such as (psycho)physiological, cognitive-verbal and behavioral mechanisms, within the context of these evaluation processes. Twenty-two females with AN (AN-G) and 22 healthy controls (HC-G) looked at pictures of their body gradually increasing in weight using a morphing technique. Implicit emotional arousal was assessed using steady-state visual evoked potentials (SSVEP) in electroencephalography. Additionally, in a forced-choice body size evaluation task, participants were asked to classify pictures of their own body as not big or big while reaction times were captured. A significantly earlier increase in SSVEPs emerged in AN-G compared to HC-G (p <.05), with AN-G evaluating their bodies in the morphing process as big at a significantly thinner body size (p <.05). The AN-G showed faster reaction times in the categorical evaluation of body stimuli (p <.05). Findings from this multimodal paradigm underline the importance of body size evaluation mechanisms and underlying emotional arousal for AN. A differentiated understanding of these processes is essential, since the effectiveness of therapeutic interventions for AN is limited and relapses are frequent.

eLoriCorps Immersive Body Rating Scale and eLoriCorps Mobile Versions: Validation to Assess Body Image Disturbances from Allocentric and Egocentric Perspectives in a Nonclinical Sample of Adolescents

A growing number of studies have used virtual reality (VR) for the assessment and treatment of body image disturbances (BIDs). This study, conducted in a community sample of adolescents, documents the convergent and discriminant validity between (a) the traditional paper-based Figure Rating Scale (paper-based FRS), (b) the VR-based Body Rating Scale (eLoriCorps-IBRS 1.1), and (c) the mobile app-based Body Rating Scale (eLoriCorps-IBRS 1.1-Mobile). A total of 93 adolescents (14 to 18 years old) participated in the study. Body dissatisfaction and body distortion were assessed through the paper-based FRS, the eLoriCorps-IBRS 1.1 and the eLoriCorps-IBRS 1.1-Mobile. Eating disorder symptoms, body image avoidance, and social physique anxiety were also measured. Correlation analyses were performed. Overall, the results showed a good and statistically significant convergence between allocentric perspectives as measured by the paper-based FRS, the eLoriCorps-IBRS 1.1 and the eLoriCorps-IBRS 1.1-Mobile. As expected, the egocentric perspective measured in VR produced different results from the allocentric perspective, and from cognitive–attitudinal–affective dimensions of BIDs, with the exception of body distortion. These differences support the discriminant validity of the egocentric perspective of eLoriCorps-IBRS 1.1 and are consistent with emerging evidence, highlighting a difference between experiencing the body from an egocentric (i.e., the body as a subject) and allocentric (i.e., the body as an object) perspective. The egocentric perspective could reflect a perceptual–sensory–affective construction of BIDs, whereas allocentric measures seem to be more related to a cognitive–affective–attitudinal construction of BIDs. Moreover, the results support the validity of the eLoriCorps-IBRS 1.1-Mobile with promising perspectives of implementation among young populations.

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.

Spatial hand representation in anorexia nervosa: a controlled pilot study

Body representation distortion (BRD) is a core criterion of Anorexia Nervosa (AN), and is usually assessed subjectively, focusing on body shape. We aimed to develop a new assessment to evaluate body representation independently from socially-mediated body image, on a body part with low emotional salience (hands). In a monocentric open label pilot study, we measured hand representations based on explicit (verbal) and implicit (tactile) instructions. Participants, with eyes closed, had to point targeted locations (knuckles and nails of each finger) based on verbal instructions and tactile stimulations to evaluate body representations respectively. Ratios between hand width and finger length were compared between AN (n = 31) and controls (n = 31) and correlated with current body mass index, AN subtype and disease duration. To control that hand distortion was specific to body representation, we also assessed object representation. Hand representation’s width/length ratio was significantly increased in patients with AN, whereas no difference was found in object representation. We found no correlation between hand wideness and clinical traits related to eating disorders. Our results propose that BRD is not limited to body parts with high emotional salience, strengthening the hypothesis that anorexia nervosa is associated with profound unspecific BRD.

Towards a Comprehensive Understanding of Body Image: Integrating Positive Body Image, Embodiment and Self-Compassion

Body image (BI) disturbance is a relevant factor in the etiology and treatment of eating disorders (ED). Although progress has been made in recent decades in understanding BI and its relationship with ED, the efficacy of BI disturbance prevention and intervention programs is still limited. In order to reach deeper understanding of BI disturbance and clarify the interactions between some protective and risk factors related to this construct, we carried out a literature review on some specific BI-related factors that so far have been analyzed independently. We specifically examined positive and negative BI; embodiment and its role in the development of positive and negative BI; and self-compassion as a protective factor that promotes positive embodiment (vs. disembodiment) and protection against body shame. We conclude that integrating the available evidence on these factors into BI models may be used to enhance our understanding of BI and improve the efficacy of prevention and intervention programs to help fight negative BI (by reducing body shame and disembodiment) and promote positive BI (by increasing self-compassion and positive embodiment).

The Perceived Match Between Observed and Own Bodies, but Not Its Accuracy, Is Influenced by Movement Dynamics and Clothing Cues

Own-perceived body matching - the ability to match one's own body with an observed body - is a difficult task for both general and clinical populations. Thus far, however, own-perceived body matching has been investigated in situations that are incongruent with how we are used to experience and perceive our body in daily life. In the current study, we aimed to examine own-perceived body matching in a context that more closely resembles real life. More specifically, we investigated the effects of body movement dynamics and clothing cues on own-perceived body matching. We asked participants to match their own body with an externally perceived body that was a 3D-generated avatar based on participants' real bodies, fitted with a computer-generated dress. This perceived body was (1) either static (non-walking avatar) or dynamic (walking avatar), (2) either bigger, smaller, or the same size as participants' own body size, and (3) fitted with a dress with a size either bigger, smaller, or the same as participants' own dress size. Our results suggest that movement dynamics cues did not improve the accuracy of own-perceived body matching, but that confidence about dress fit was higher for dynamic avatars, and that the difference between dynamic and static avatars was dependent on participants' self-esteem. Furthermore, when participants were asked to rate the observed body in reference to how they wanted to represent themselves to others, dynamic avatars were rated lower than static avatars for the biggest-sized bodies only, possibly reflecting the influence of movement cues on amplifying socio-cultural stereotypes. Finally, while smaller body/dress sizes were systematically rated higher than bigger body/dress sizes for several self-report items, the interplay between body and dress size played an important role in participants' self-report as well. Thus, while our research suggests that movement and garment dynamics, allowing for realistic, concrete situations that are reminiscent of daily life, influence own-body perception, these cues did not lead to an improvement in accuracy. These findings provide important insights for research exploring (own-) body perception and bodily self-awareness, with practical (e.g., development of online avatars) and clinical (e.g., anorexia nervosa and body dysmorphic disorder) implications.

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.

Changing your body changes your eating attitudes: embodiment of a slim virtual avatar induces avoidance of high-calorie food

The virtual-reality full-body illusion paradigm has been suggested to not only trigger the illusory ownership of the avatar's body but also the attitudinal and behavioral components stereotypically associated to that kind of virtual body. In the present study, we investigated whether this was true for stereotypes related to body size: body satisfaction and eating control behavior. Healthy participants underwent the full-body illusion paradigm with an avatar having either a larger or a slimmer body than their own, and were assessed for implicit attitudes towards body image and food calorie content at baseline and after each full-body illusion session. Results showed that the illusion emerged regardless of the avatar's body size, whereas the perceived dimension of the own body size changed according to the avatar's body size (i.e., participants felt to be slimmer after embodying their slim avatar and larger after embodying their large avatar). Crucially, we found that implicit attitudes towards food, but not those towards one's own body, were modulated by the size of the virtual body. Compared to baseline, ownership of a slimmer avatar increased the avoidance of high-calorie food, whereas ownership of a larger avatar did not induce changes. Our findings suggest that the illusory feeling of being slimmer drives also the food-related stereotypes associated with that body size, increasing the regulation of eating behaviors.

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.

Targeting body image in eating disorders

Eating disorders, such as anorexia nervosa, are challenging to treat successfully and have a very high relapse rate. Body image disturbance (BID) is a core component of these eating disorders. It is a predictor of onset, treatment outcome and future relapse. However, recent studies suggest that BID can be improved by an adaptation of cognitive bias training. This does not target the accuracy of body size judgements, but instead focuses on how a body of a particular size is categorized by a patient. This recalibration of the categorical boundary at which bodies are judged as overweight, which challenges a patient's existing preconceptions about which constitutes an acceptable body size, seems to lead to a more general reassessment of eating disordered attitudes and a significant improvement in their psychological profile. These promising findings need further trials to determine the long-term effectiveness of such a targeted intervention, but it potentially provides an important additional treatment option. In addition, this cognitive bias training may also be an effective augmentation to treatment in other conditions that feature BID, such as bulimia nervosa and body dysmorphia.

[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 size overestimation in anorexia nervosa: Contributions of cognitive, affective, tactile and visual information

Body image disturbance (BID) in anorexia nervosa (AN) is poorly understood and the individual contribution of perceptual, cognitive, and affective components remains unclear. This study compared females with AN and matched healthy controls (HC) on a perceptual size estimation task. Participants (AN n=19 M[SD] age=16.97[2.24], HC n=19, age=15.77[2.17]) were blindfolded and estimated the size of neutral objects, safe foods, unsafe foods, and parts of their bodies (hips, waist, knees, ankle) over three blocks using: 1) no sensory information (baseline), 2) tactile information, and 3) added visual information. There were no significant differences between AN and HC on neutral and safe or unsafe food objects. Participants with AN were significantly more likely to overestimate their body size across blocks compared to HC. Both groups made fewer errors on unsafe foods and body parts when using tactile or visual information compared to baseline. Exploratory analyses revealed significant correlations between body size overestimation and drive for thinness and body dissatisfaction in the AN group, with body dissatisfaction being the most robust. Results suggest that both deficits in tactile and visual perception and affective factors play a role in BID for young women with AN.

Body image disturbance in children and adolescents with anorexia nervosa and bulimia nervosa: a systematic review

PURPOSE

While several meta-analyses and reviews revealed a worse body image disturbance (BID) in adults with anorexia nervosa (AN) or bulimia nervosa (BN) than in controls, no systematic evidence is available on BID in children and adolescents. Since the usual onset of AN and BN is before the age of 21 years, being aware of BID in children and adolescents is crucial for preventing and treating eating disorders. This systematic review aims to provide an initial overview of differences in the BID components perception, global subjective satisfaction, affect/cognition, and behavior between children and adolescents with AN and BN and healthy controls.

METHODS

We conducted a systematic data search in PubMed and PsycINFO based on a priori eligibility criteria (AN or BN group; gender-matched healthy control group; each group n ≥ 20; maximum age 19 years; BID outcome compared between groups; published in English or German).

RESULTS

We were able to include k = 8 records. Compared to healthy controls, children and adolescents with AN and BN scored higher in the BID components perception, global subjective satisfaction, affect/cognition, and behavior.

CONCLUSIONS

As previously found in adults, BID in children and adolescents is associated with AN and BN. Interventions and treatments are needed to alleviate BID in children and adolescents with BN and AN. We also noted that we need more investigations on BID differences in children and adolescents to improve the database.

LEVEL OF EVIDENCE

Level I, Systematic review.

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).

Using immersive virtual reality to modify body image

We tested the efficacy of a training programme, delivered in virtual reality (VR), to modify the perceptual boundary between what participants classify as a fat versus a thin body. Three cohorts of 20 female volunteers with high body image concerns were recruited to two intervention groups and one control group. All participants completed a 4-day training programme in VR where they categorised a series of 3D models as either thin or fat; one intervention group was presented with the stimuli briefly, while the other group had no time limits imposed. Both intervention groups were given inflationary feedback to shift their categorisations of the stimulus models towards higher BMIs. Our results show that, compared to controls, both intervention groups shifted their categorical boundaries between Day 1 and follow-up on Day 14. Unlimited stimulus presentation times were associated with a larger training effect. Furthermore, both intervention groups experienced statistically significant reductions in their concerns about their own body shape, weight and eating habits. However, only in the group with longer stimulus presentation times were these reductions consistent with a clinically meaningful effect. These findings suggest that manipulating categorical perception in VR might provide a complementary addition to existing treatments for eating disorders.

Time course of body recognition in women with weight and shape concerns assessed by steady-state visual evoked potentials (SSVEP)

This study aimed to examine self-body recognition in women with high (HWSC) and low weight and shape concerns (LWSC). Thus, the detection rate, the reaction time and the perceptual threshold for recognizing one's own body in a morphed body were measured in n = 25 women with HWSC and n = 26 women with LWSC. Furthermore, by using steady-state visual evoked potentials (SSVEPs), neuronal correlates of body recognition were recorded. The perceptual threshold for recognizing one's own body was higher for women with HWSC in the case of a morph with a thinner body. No group differences emerged for morphs with obese or average-weight bodies. The SSVEP amplitudes did not differentiate between one's own and another body in either group. The results suggest that for women with HWSC, their negative body schemata might hamper recognition of their own body in a thinner morph. Otherwise, self-body recognition is similar in women with LWSC and HWSC.

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.

The Representation of Body Size: Variations With Viewpoint and Sex

Perceived body size is a fundamental construct that reflects our knowledge of self and is important for all aspects of perception, yet how we perceive our bodies and how the body is represented in the brain is not yet fully understood. In order to understand how the brain perceives and represents the body, we need an objective method that is not vulnerable to affective or cognitive influences. Here, we achieve this by assessing the accuracy of full-body size perception using a novel psychophysical method that taps into the implicit body representation for determining perceived size. Participants were tested with life-size images of their body as seen from different viewpoints with the expectation that greater distortions would occur for unfamiliar views. The Body Shape Questionnaire was also administered. Using a two-alternative forced choice design, participants were sequentially shown two life-size images of their whole body dressed in a standardized tight-fitting outfit seen from the front, side, or back. In one image, the aspect ratio (with the horizontal or vertical dimension fixed) was varied using an adaptive staircase, while the other was undistorted. Participants reported which image most closely matched their own body size. The staircase honed in on the distorted image that was equally likely as the undistorted photo to be judged as matching their perception of themselves. From this, the perceived size of their internal body representation could be calculated. Underestimation of body width was found when the body was viewed from the front or back in both sexes. However, females, but not males, overestimated their width when the body was viewed from the side. Height was perceived accurately in all views. These findings reveal distortions in perceived size for healthy populations and show that both viewpoint and sex matter for the implicit body representation. Though the back view of one’s body is rarely–if ever–seen, perceptual distortions were the same as for the front view. This provides insight into how the brain might construct its representation of three-dimensional body shape.

Characterizing Body Image Distortion and Bodily Self-Plasticity in Anorexia Nervosa via Visuo-Tactile Stimulation in Virtual Reality

We combined virtual reality and multisensory bodily illusion with the aim to characterize and reduce the perceptual (body overestimation) and the cognitive-emotional (body dissatisfaction) components of body image distortion (BID) in anorexia nervosa (AN). For each participant (20 anorexics, 20 healthy controls) we built personalized avatars that reproduced their own body size, shape, and verisimilar increases and losses of their original weight. Body overestimation and dissatisfaction were measured by asking participants to choose the avatar that best resembled their real and ideal body. Results show higher body dissatisfaction in AN, caused by the desire of a thinner body, and no body-size overestimation. Interpersonal multisensory stimulation (IMS) was then applied on the avatar reproducing participant’s perceived body, and on the two avatars which reproduced increases and losses of 15% of it, all presented with a first-person perspective (1PP). Embodiment was stronger after synchronous IMS in both groups, but did not reduce BID in participants with AN. Interestingly, anorexics reported more negative emotions after embodying the fattest avatar, which scaled with symptoms severity. Overall, our findings suggest that the cognitive-emotional, more than the perceptual component of BID is severely altered in AN and that perspective (1PP vs. 3PP) from which a body is evaluated may play a crucial role. Future research and clinical trials might take advantage of virtual reality to reduce the emotional distress related to body dissatisfaction.

Muscle and fat aftereffects and the role of gender: Implications for body image disturbance

Body image disturbance - a cause of distress amongst the general population and those diagnosed with various disorders - is often attributed to the media's unrealistic depiction of ideal bodies. These ideals are strongly gendered, leading to pronounced fat concern amongst females, and a male preoccupation with muscularity. Recent research suggests that visual aftereffects may be fundamental to the misperception of body fat and muscle mass - the perceptual component of body image disturbance. This study sought to establish the influence of gender on these body aftereffects. Male and female observers were randomly assigned to one of four adaptation conditions (low-fat, high-fat, low-muscle, and high-muscle bodies) and were asked to adjust the apparent fat and muscle levels of male and female bodies to make them appear as 'normal' as possible both before adaptation and after adaptation. While neither the gender of observers nor of body stimuli had a direct effect, aftereffect magnitude was significantly larger when observers viewed own-gender (compared with other-gender) stimuli. This effect, which may be due to attentional factors, could have implications for the development of body image disturbance, given the preponderance of idealized own-gender bodies in media marketed to male and female consumers.

The Cash effect: Shaping the research conversation on body image and eating disorders

Cash and Deagle (1997) examined the associations between body image disturbance (BID) and the eating disorders (EDs) of anorexia nervosa (AN) and bulimia nervosa (BN) in a meta-analytic review. They found almost twice as many studies employing perceptual measures of body size evaluation compared to cognitive-evaluative measures of body dissatisfaction, even though effect sizes were larger for studies with cognitive-evaluative measurement. We examined 109 "influential" (i.e., well-cited) studies that cited the Cash and Deagle meta-analysis. We found a slight, continued emphasis on research using body size evaluation measures that implied a biological correlate for perceptual differences (especially for those with AN). We found proportionally more studies using cognitive-evaluative measures than was true in 1997, and more variability in the types of measures used. In these studies researchers emphasized the role of sociocultural factors in the link between BID and EDs. Theory and research that integrate a variety of factors to conceptualize the association between BID and EDs are still needed.

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.

Looking at the Figures: Visual Adaptation as a Mechanism for Body-Size and -Shape Misperception

Many individuals experience body-size and -shape misperception (BSSM). Body-size overestimation is associated with body dissatisfaction, anxiety, depression, and the development of eating disorders in individuals who desire to be thinner. Similar symptoms have been noted for those who underestimate their muscularity. Conversely, individuals with high body mass indices (BMI) who underestimate their adiposity may not recognize the risks of or seek help for obesity-related medical issues. Although social scientists have examined whether media representations of idealized bodies contribute to the overestimation of fat or underestimation of muscle, other scientists suggest that increases in the prevalence of obesity could explain body-fat underestimation as a form of renormalization. However, these disparate approaches have not advanced our understanding of the perceptual underpinnings of BSSM. Recently, a new unifying account of BSSM has emerged that is based on the long-established phenomenon of visual adaptation, employing psychophysical measurements of perceived size and shape following exposure to "extreme" body stimuli. By inducing BSSM in the laboratory as an aftereffect, this technique is rapidly advancing our understanding of the underlying mental representation of human bodies. This nascent approach provides insight into real-world BSSM and may inform the development of therapeutic and public-health interventions designed to address such perceptual errors.

An Assessment of Computer-Generated Stimuli for Use in Studies of Body Size Estimation and Bias

Inaccurate body size judgments are associated with body image disturbances, a clinical feature of many eating disorders. Accordingly, body-related stimuli have become increasingly important in the study of estimation inaccuracies and body image disturbances. Technological advancements in the last decade have led to an increased use of computer-generated (CG) body stimuli in body image research. However, recent face perception research has suggested that CG face stimuli are not recognized as readily and may not fully tap facial processing mechanisms. The current study assessed the effectiveness of using CG stimuli in an established body size estimation task (the “bodyline” task). Specifically, we examined whether employing CG body stimuli alters body size judgments and associated estimation biases. One hundred and six 17- to 25-year-old females completed the CG bodyline task, which involved estimating the size of full-length CG body stimuli along a visual analogue scale. Our results show that perception of body size for CG stimuli was non-linear. Participants struggled to discriminate between extreme bodies sizes and overestimated the size change between near to average bodies. Furthermore, one of our measured size estimation biases was larger for CG stimuli. Our collective findings suggest using caution when employing CG stimuli in experimental research on body perception.

Investigating the Components of Body Image Disturbance Within Eating Disorders

Body image disturbance has been highlighted as a common characteristic within the development and maintenance of clinical eating disorders (EDs), represented by alterations in an individual's bodily experience. However, whilst the perceptual stability of the sense of body ownership has been investigated in ED patients, the stability of the sense of body agency in those with ED is yet to be examined. Therefore, body ownership and body agency were investigated using the moving rubber hand illusion, alongside measures of explicit and implicit body satisfaction. Furthermore, with evidence demonstrating a direct link between perceptual and cognitive-affective components of body image in the healthy population, the relationship between measures of body perception and body satisfaction was investigated. Results showed that both ED and healthy individuals displayed a similar subjective experience of illusory ownership and agency towards the fake hand, following voluntary movement. However, whilst both groups initially overestimated their own hand width prior to the illusion, the ED group displayed a significant reduction in hand size estimation following the illusion, which was not matched to the same degree in healthy individuals. In addition, ED individuals displayed a significantly lower body satisfaction compared with healthy females, on both an explicit and implicit level. Such implicit outcomes were shown to be driven specifically by a weaker association between the self and attractiveness. Finally, a significant relationship was observed between specific perceptual measures and implicit body satisfaction, which highlights the important link between perceptual and cognitive-affective components of one's body image. Together, such findings provide a useful foundation for further research to study the conditions in which these two components relate with regard to body image and its disturbance, particularly in relation to the prognosis and treatment of EDs.

Evidence for a perceptual mechanism relating body size misperception and eating disorder symptoms

PURPOSE

There are known and serious health risks associated with extreme body weights, including the development of eating disorders. Body size misperceptions are particularly evident in individuals with eating disorders, compared to healthy controls. The present research investigated whether serial dependence, a recently discovered bias in body size judgement, is associated with eating disorder symptomatology. We additionally examined whether this bias operates on holistic body representations or whether it works by distorting specific visual features.

METHODS

A correlational analysis was used to examine the association between serial dependence and eating disorder symptomatology. We used a within-subjects experimental design to investigate the holistic nature of this misperception. Participants were 63 young women, who judged the size of upright and inverted female body images using a visual analogue scale and then completed the Eating Disorder Examination-Questionnaire (EDE-Q) to assess eating disorder symptoms.

RESULTS

Our findings provide the first evidence of an association between serial dependence and eating disorder symptoms, with significant and positive correlations between body size misperception owing to serial dependence and EDE-Q scores, when controlling for Body Mass Index. Furthermore, we reveal that serial dependence is consistent with distortion of local visual features.

CONCLUSIONS

Findings are discussed in relation to the broader theories of central coherence, cognitive inflexibility, and multisensory integration difficulties, and as providing a candidate mechanism for body size misperception in an eating disorder population.

LEVEL OF EVIDENCE

Level 1, experimental study.

Visuo-tactile congruency influences the body schema during full body ownership illusion

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Visuo-tactile congruency influences the body schema, but not the body image.

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Movement behavior may provide a window into the unconscious body schema.

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We present novel methods to distort avatars and Euclidean space in virtual reality.

Previous research showed that full body ownership illusions in virtual reality (VR) can be robustly induced by providing congruent visual stimulation, and that congruent tactile experiences provide a dispensable extension to an already established phenomenon. Here we show that visuo-tactile congruency indeed does not add to already high measures for body ownership on explicit measures, but does modulate movement behavior when walking in the laboratory. Specifically, participants who took ownership over a more corpulent virtual body with intact visuo-tactile congruency increased safety distances towards the laboratory’s walls compared to participants who experienced the same illusion with deteriorated visuo-tactile congruency. This effect is in line with the body schema more readily adapting to a more corpulent body after receiving congruent tactile information. We conclude that the action-oriented, unconscious body schema relies more heavily on tactile information compared to more explicit aspects of body ownership.