Body size perception in anorexia nervosa: a signal detection approach.

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

Body perception index: benefits, pitfalls, ideas.

Estimates of body size are often expressed as a ratio of actual size [body perception index or BPI = (estimated size/actual size) x 100%]. In this article, we examine the possibility that overestimation of body size in patients with anorexia nervosa, as measured by the BPI, is due to their smaller body size rather than to their being anorexic. Using 50 mean body sizes derived from seven studies we investigated whether the error of estimation is a constant proportion of the body size to be estimated, as the use of the BPI assumes. A negative linear relation between BPI and actual body size was found, confirming that smaller size is associated with greater overestimation. However, although both groups showed a strong tendency to overestimate smaller sizes, anorexic subjects showed even greater overestimation than controls. Hence, overestimation of body size in AN can only partially be accounted for by the smaller body size of anorexic patients. Recommendations for future use of the BPI are put forward.

The influence of methodological differences on the outcome of body size estimation studies in anorexia nervosa.

A major problem that has dogged research into body image disturbance in anorexia nervosa concerns the diversity of measurement procedures employed in studies of body size estimation. Many researchers believe that results obtained with different procedures cannot meaningfully be compared with each other, because the methods used measure different aspects of the body image. A meta-analysis of 33 body size estimation studies was conducted to investigate whether methodological differences do indeed influence outcome. This analysis revealed a general overestimation of body size among anorexia patients. Although a difference in mean effect size was found between studies using Body Part and Whole Body methods, this difference was absent when only the most commonly used Body Part method, the visual size estimation procedure, was considered. Among Whole Body methods, silhouette methods could not be distinguished from the rest in terms of effect size. It was concluded that Whole Body methods and the visual size estimation procedure assess correlated aspects of the body image.