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.

Men's perception of current and ideal body composition and the influence of media internalization on body judgements.

Introduction: To determine men's body ideals and the factors that influence these choices, this study used a matrix of computer generated (CG) male bodies (based on an analysis of 3D scanned real bodies) which independently varied in fat and muscle content. Methods: Two hundred and fifty-eight male participants completed a range of psychometric measures to index body concerns and body ideal internalization and then chose the CG body that best reflected their own current body, as well as the body that reflected their personal ideal. A subset of participants was then retested to check that these judgements were stable over time. Results: While judgements of the ideal body seem to be influenced by a shared appearance ideal, the degree to which this ideal was internalized showed significant variability between participants. The effect of this internalization was reflected in the difference between the estimated current body and the ideal. Discussion: Higher internalization led to a preference for higher muscle and lower fat content. This preference was most marked for fat content, although reducing adiposity also made the underlying musculature more salient. Additionally, the ideal body composition was modulated by the composition the participant believed his current body had (i.e., it seemed that a participant's ideal body was anchored by what they believed to be their current body and what change was possible from this starting point).

The Effect of Own Body Concerns on Judgments of Other Women's Body Size.

We investigated the relationships between healthy women's estimates of their own body size, their body dissatisfaction, and how they subjectively judge the transition from normal to overweight in other women's bodies (the "normal/overweight" boundary). We propose two complementary hypotheses. In the first, participants compare other women to an internalized Western "thin ideal," whose size reflects the observer's own body dissatisfaction. As dissatisfaction increases, so the size of their "thin ideal" reduces, predicting an inverse relationship between the "normal/overweight" boundary and participants' body dissatisfaction. Alternatively, participants judge the size of other women relative to the body size they believe they have. For this implicit or explicit social comparison, the participant selects a "normal/overweight" boundary that minimizes the chance of her making an upward social comparison. So, the "normal/overweight" boundary matches or is larger than her own body size. In an online study of 129 healthy women, we found that both opposing factors explain where women place the "normal/overweight" boundary. Increasing body dissatisfaction leads to slimmer judgments for the position of the "normal/overweight" boundary in the body mass index (BMI) spectrum. Whereas, increasing overestimation by the observer of their own body size shifts the "normal/overweight" boundary toward higher BMIs.

Fat talk is predicted by body dissatisfaction and social comparison with no interaction effect: Evidence from two replication studies.

Verbal denigration of personal body size and shape ("fat talk") is correlated with, and can have a causal influence on body dissatisfaction and disordered eating. What is less clear is who is most likely to fat talk. To address this, Corning and Gondoli (2012) conducted a study confirming that a woman's body dissatisfaction directly predicted their fat talk. But this effect was scaled so that the likelihood of engaging in fat talk intensified if she had a stronger tendency to socially compare: the relationship was multiplicative. Here, we carried out two replications of Corning and Gondoli's (2012) study, the first with 189 UK participants and the second with 371 US participants. We found that multiple regression models predicting fat talk showed additive, but not multiplicative relationships. A robust Bayesian meta-analysis combining the results of our two studies with the results of the original study confirmed this. In conclusion, these studies show an additive relationship between fat talk and social comparison on fat talk.

Women's self-estimates of body size are more accurate and precise when made with three-quarter view than front-view stimuli.

Recently, Cornelissen, Cornelissen, Groves, McCarty and Tovée (2018) asked which image orientations (e.g. front-, side-, or three-quarter view) are most appropriate for tasks which are used for self-estimates of body size and shape. Based on psychophysical measurements, they showed that front view stimuli showed substantially poorer content validity compared to side- and three-quarter view stimuli. Here, we tested the real-world consequences of Cornelissen et al.'s (2018) findings. We carried out a body size self-estimation task in a sample of healthy adult women, once with front view stimuli, and once with three-quarter view stimuli. The order in which front- and three-quarter view tasks were carried out was randomized across participants. Compared to three-quarter view stimuli, we found that: a) the precision of participants' judgements was worse with front view stimuli, and b) that front view stimuli led to over-estimation of body size by ∼1.7 BMI units. While these results need to be replicated, they do suggest that careful consideration needs to be given to stimulus orientation in future studies.

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.

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.

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.

View-dependent accuracy in body mass judgements of female bodies.

A fundamental issue in testing body image perception is how to present the test stimuli. Previous studies have almost exclusively used images of bodies viewed in front-view, but this potentially obscures key visual cues used to judge adiposity reducing the ability to make accurate judgements. A potential solution is to use a three-quarter view, which combines visual cues to body fat that can be observed in front and profile. To test this hypothesis, 20 female observers completed a 2-alternative forced choice paradigm to determine the smallest difference in body fat detectable in female bodies in front, three-quarter, and profile view. There was a significant advantage for three-quarter and profile relative to front-view. Discrimination accuracy is predicted by the saliency of stomach depth, suggesting that this is a key visual cue used to judge body mass. In future, bodies should ideally be presented in three-quarter to accurately assess body size discrimination.

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.

An interactive training programme to treat body image disturbance.

OBJECTIVES: Anorexia nervosa (AN) is a life-threatening mental health condition. A core feature is a disturbance of body image, such that sufferers see themselves as fatter than they actually are. DESIGN: We tested the effectiveness of a novel training programme to recalibrate our participants' perception of body size. METHODS: In a novel adaptation of a cognitive bias training programme, participants judged the body size of a series of female bodies and were given feedback to improve their accuracy over four daily training sessions. In Study 1, we recruited young women with high concerns about their body size for a randomized controlled study. In Study 2, we then applied the training programme to a case series of women with atypical AN. RESULTS: In Study 1, the training programme significantly improved the body size judgements of women with high body concerns compared to controls. We also found evidence of improved body image and reduced eating concerns in this group. In Study 2, the programme again recalibrated the body size judgements of women with atypical AN. We also saw evidence of a clinically meaningful reduction in their body size and eating-disordered concerns. CONCLUSIONS: This training has the potential to be a valuable treatment used together with more traditional talking therapies. Statement of contribution What is already known on this subject? A core feature of anorexia nervosa (AN) is an overestimation of body size; sufferers believe themselves to be larger than they are in reality. This study shows that an individual's perceptual boundary between what they classify as a fat versus a thin body is not immutable; it can be changed through a cognitive bias training programme. What does this study add? This means that body size overestimation may now be treatable. Critically, as well as improving the accuracy of body size judgements, we also found a clinically significant improvement in participants' eating-disordered concerns. This demonstrates that a targeted behavioural training regime can change body perception, and the central role that body overestimation has in eating-disordered beliefs.

Fixation patterns, not clinical diagnosis, predict body size over-estimation in eating disordered women and healthy controls.

OBJECTIVE: A core feature of anorexia nervosa (AN) is an over-estimation of body size. Women with AN have a different pattern of eye-movements when judging bodies, but it is unclear whether this is specific to their diagnosis or whether it is found in anyone over-estimating body size. METHOD: To address this question, we compared the eye movement patterns from three participant groups while they carried out a body size estimation task: (i) 20 women with recovering/recovered anorexia (rAN) who had concerns about body shape and weight and who over-estimated body size, (ii) 20 healthy controls who had normative levels of concern about body shape and who estimated body size accurately (iii) 20 healthy controls who had normative levels of concern about body shape but who did over-estimate body size. RESULTS: Comparisons between the three groups showed that: (i) accurate body size estimators tended to look more in the waist region, and this was independent of clinical diagnosis; (ii) there is a pattern of looking at images of bodies, particularly viewing the upper parts of the torso and face, which is specific to participants with rAN but which is independent of accuracy in body size estimation. DISCUSSION: Since the over-estimating controls did not share the same body image concerns that women with rAN report, their over-estimation cannot be explained by attitudinal concerns about body shape and weight. These results suggest that a distributed fixation pattern is associated with over-estimation of body size and should be addressed in treatment programs. © 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:507-518).

Visual biases in judging body weight.

OBJECTIVES: There has been a steady rise in obesity levels in Western countries, and a contributory factor is people's failure to recognize weight gain. Two important visual perceptual biases, contraction bias and Weber's law, that have hitherto been ignored in the obesity literature could contribute to this problem. Contraction bias predicts that the weight of obese bodies will be underestimated and the degree of underestimation will increase as body mass index (BMI) increases. Weber's law predicts that change in the body size will become progressively harder to detect as their BMI increases. METHODS: In Experiment 1, 29 women participants estimated the weight of 120 women varying in their body mass. In Experiment 2, 28 women participants judged which body was the heavier in a 2-alternative forced choice paradigm. RESULTS: In Experiment 1, as predicted the participants showed a progressive underestimation of overweight and obese bodies, ß1  = 0.71, t = 26.96, p < .0001. For Experiment 2, there was a significant effect of the BMI of the bodies being judged on the just noticeable difference needed to discriminate between them: F(1, 196) = 89.39, p < .0001 for 3D bodies and F(1, 86.5) = 44.57, p < .0001 for digital photographs. CONCLUSIONS: Normal visual perceptual biases influence our ability to determine body size: contraction bias and Weber's law mean that as bodies become overweight and obese, it is harder to judge their weight and detect any increase in size. These effects may therefore compromise people's ability to recognize weight gain and undertake compensatory weight control behaviours. Statement of contribution What is already known on this subject? It is common knowledge that obesity levels in the West are rapidly rising and that people fail to recognize weight gain. What has not been widely recognized before is that there are sound perceptual reasons for this failure. Here, we identify two such perceptual biases. What does this study add? Weber's law and contraction bias compromise people's ability to recognize weight gain. It becomes progressively harder to discriminate the size of bodies as their body mass index increases. This compromises the ability to recognize weight gain and undertake compensatory behaviours.

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.