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Abstract

Previous research on own body size estimation has only looked at estimates made by comparing own body size to a test body in front view (e.g., Mölbert et al. 2017). However, people constantly see and compare themselves to bodies in different viewpoints. Depending on the viewpoint, shape cues potentially used to judge body size, such as the waist-to-hip ratio or the overall body outline, vary. Here, we asked whether viewpoint influences estimates of own body size in female participants. For each participant, a personalized female avatar was generated using weight, height, inseam, and arm span, and then variations of the personalized avatar having different weights (±5, ±10, ±15, ±20, and ±25) were created using a statistical body model. These eleven test bodies were presented in life-size in immersive virtual reality in six viewpoints: 0°, ±45°, ±90°, 180°. In a one-alternative forced choice paradigm, participants were asked to judge whether the test body was thinner or fatter than themselves. Results showed no significant influence of viewpoint on either the accuracy of body size estimation (PSE) or the sensitivity to weight changes (JND). Across all viewpoints, participants on average slightly overestimated their body weight (3.1) and could detect a weight difference of 5.2 in 50 of the trials. To further investigate whether females are also able to estimate own body size when the shape of the test bodies is clearly different to theirs, a set of personalized male avatars was generated for each participant and presented in front view using the same task. There was no difference in results between female and male test bodies. These results suggest that people are rather good at extracting body size independent of the viewpoint, and also from bodies with a very different shape.