Perceptual body image tasks require ethnically appropriate stimuli

Current body ideals and perceived weight status are often assessed with tests that include images which depict BMI dependent morphological changes in body shape. These images are almost exclusively based on White European (WE) bodies. However, East Asian (EA) and South Asian (SA) people have a different body composition and pattern of adipose deposition for a given BMI. As such, matching someone's body from an EA or SA background to a WE body may lead to errors in estimation, as there are no equivalent bodies to match against. Therefore, we 3D scanned EA, SA and WE female volunteers and constructed computer-generated imagery (CGI) bodies based on a statistical analysis of the size and shape variation specific to each ethnic identity. We then asked participants to make judgements between pairs of bodies of the same or different ethnic identity as themselves. When presented with ethnically different stimuli, EA and SA participants significantly over-estimate body size and WE participants significantly under-estimate. Additionally, ethnically mismatched stimuli lead to significantly greater uncertainty about body size judgements. For the first time, we show that ethnically appropriate stimuli need to be used to assess body judgements and should be developed as a matter of urgency.