The exposure to body size distortions affects allocentric distance perception in extra-personal space

Abstract

Previous research demonstrated that body size distortions induced by body illusion can influence spatial perception in near space. We investigated whether manipulating body size through a Full-Body Illusion-like paradigm influences allocentric distance perception in extra-personal space. Participants estimated the distance between landmarks in far space before and after a body illusion with standard or big bodies in anatomical (i.e., virtual and actual legs were aligned) or non-anatomical orientation (i.e., virtual legs were rotated by 45 degrees). We analysed space perception via Multidimensional Scaling for landmark configuration and distance misestimation. Embodiment occurred with bodies in anatomical orientation, while exposure to bigger bodies increased perceived distance, regardless of the presence of the embodiment. However, no significant changes emerged in the perception of landmark configuration. Findings indicated that, in extra-personal space, the distance perception between objects, rather than their shape configuration, is scaled based on a metric reference related to a seen body.