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

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