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 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.

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.