Body size estimations: the role of visual information from a first-person and mirror perspective

Our perception of our body, and its size, is important for many aspects of everyday life. Using a variety of measures, previous research demonstrated that people typically overestimate the size of their bodies (Longo Haggard, 2010). Given that self-body size perception is informed from many different experiences, it is surprising that people do not perceive their bodies veridically. Here, we asked, whether different visual experiences of our bodies influence how large we estimate our body’s size. Specifically, participants estimated the width of four different body parts (feet, hips, shoulders, and head) as well as a noncorporeal object with No Visual Access, Self-Observation (1st person visual access), or looking through a Mirror (2nd person visual access) using a visual matching task. If estimates when given visual access (through mirror or 1st person perspective) differ from estimates made with no visual access, it would suggest that this method of viewing one’s body has less influence on how we represent the size of our bodies. Consistent with previous research, results demonstrated that in all conditions, each body part was overestimated. Interestingly, in the No Visual Access and Mirror conditions, the degree of overestimation was larger for upper body parts compared to lower body parts and there were no significant differences between the No Visual Access and Mirror conditions. There was, however, a significant difference between the Self-Observation condition and the other two conditions when estimating ones shoulder width. In the Self-Observation condition, participants were more accurate with estimating shoulder width. The similarity of results in the No Visual Access and Mirror conditions suggests that our representation of our body size may be partly based on experiences viewing one’s body in reflective surfaces