The Sense of Body Ownership Shapes the Visual Representation of Body Size

The conscious body image includes the visual representation of body-parts size; whether this component of body perception can flexibly adapt to changes of the sense of ownership of one’s body-parts remains to be demonstrated. The present study addresses this issue, showing that the ownership of a novel hand affects the conscious visual perception of the size of the really owned hand. Through a series of experiments in healthy adults, we assess how the embodiment of fake hands of different sizes (i.e., Rubber Hand Illusion, RHI) affects visual size estimation of the own hand. Our results demonstrate that the embodiment of a fake hand bigger in size than the own hand (Experiment 1), but not of a smaller fake hand (Experiment 2), affects the perception of similarity in size between the own hand and a visual model of the own hand, with a tendency toward an overestimation of the size of the hand exposed to the RHI (Experiment 1). The illu-sory ownership of a bigger hand does not affect the visual estimate of object size (Experiment 3). These findings show the tight link between the body image and the sense of ownership, the latter being able to change stored representations of body-parts size. This evidence might pave the way for restoring pathologi-cal alteration of body image through strategies accessing the body schema.