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

Abstract

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.

Mirror exposure following visual body-size adaptation does not affect own body image

“…Consequently, the fact that these aftereffects have been observed after prolonged exposure to an extreme body size suggests that adaptation only affects test stimuli, whereas participants' internal body image remains unchanged, contrary to some interpretations of adaptation aftereffects (e.g. [ 10 ]). Ambroziak et al .…”

“…Exposure to low-BMI bodies in the mass media is linked to body shape misperception, in association with body dissatisfaction and eating disorders [ 1 ]. Some authors have mentioned [ 4 , 13 , 18 ] or argued [ 10 ] that this phenomenon is partly due to adaptation aftereffects caused by prolonged and repeated exposure to low-BMI bodies. After adapting to thin media figures, people should see all bodies as larger than before and, according to the internalization hypothesis, the distorted reflection of their own body in the mirror could influence their perceptual body image [ 13 ].…”

“…First, body representation is highly flexible and can be altered rapidly, as is most spectacularly demonstrated in body illusions [ 37 ]. Second, body-size adaptation aftereffects seem to last relatively long, as illustrated by the detection of aftereffects 18 min after a 5 min adaptation period, but they also somewhat tend to fade with time [ 10 ]. If mirror exposure was sustained, the perceptual aftereffects should further diminish with time, as the participants' own reflection might cause a deadaptation, progressively nullifying the initial aftereffects.…”

“…This media influence could pose a public health problem, as misperception of one's own body shape is a risk and severity factor in eating disorders such as anorexia nervosa [5]. This misperception resembles the aftereffects of visual adaptation to extreme body sizes [6–10]. In this study, we investigated the hypothesis that adaptation can specifically affect participants' own body image.…”

“…Authors have indeed proposed that visual adaptation could help develop an ‘experimental model of body image distortion’ [ 8 , p. 9]. Some authors have taken this idea a step further, interpreting adaptation aftereffects as proof that ‘[visual adaptation] impacts the internal representation of body size' [ 10 , p. 9]. The perceptual component of body image, understood as a stored representation [ 13 ] with which ‘a person can judge the physical dimensions of their own body' [ 14 , p. 35], could well be influenced by visual adaptation.…”