The Role of Visual Information in Body Size Estimation

Abstract

The conscious representation of our physical appearance is important for many aspects of everyday life. Here, we asked whether different visual experiences of our bodies influence body width estimates. In Experiment 1, width estimates of three body parts (foot, hips, and shoulders) without any visual access were compared to estimates with visual feedback available in a mirror or from a first-person perspective. In the no visual access and mirror condition, participants additionally estimated their head width. There was no influence of viewing condition on body part width estimates. Consistent with previous research, all body part widths were overestimated with greater overestimation of hip and head width. In Experiment 2, participants estimated the size of unfamiliar noncorporeal objects to test whether this overestimation was partially due to the metric body size estimation method or our experimental conditions. Object width was overestimated with visual feedback in a mirror available as compared to when directly looking at the object, but only for objects placed at shoulder and head height. We conclude that at least some of the overestimation of body part width seems to be body specific and occurs regardless of the visual information provided about the own body.

Keywords: body image; body perception; body size estimation; mirror; visual perspective.

Figure 1.

Overview of the three experimental conditions in Experiment 1. Participants either estimated their body size without visual access with visual feedback in the mirror available or from a first-person perspective.

Figure 2.

Body perception index as a function of body part, collapsed across the three experimental conditions of Experiment 1. Values higher than 100 indicate overestimation in terms of percentage of the actual body size. Error bars represent one standard error from the mean.

Figure 3.

Overview of the two experimental conditions in Experiment 2. Participants either estimated the object widths attached to the occluder with visual feedback in the mirror available or by directly looking at the objects without a mirror.

Figure 4.

Object perception index for objects placed at the height of each participant’s right foot, hip, shoulder, and head when viewed directly (no mirror) or when viewed in a mirror (mirror) in Experiment 2. Values higher than 100 indicate overestimation in terms of percentage of the actual size. Error bars represent one standard error from the mean.