Welcome to Wonderland: The Apparent Size of the Body Influences Perceived Extents in Virtual Environments

Abstract

According to the functional approach to the perception of spatial layout, angular optic variables that indicate extents are scaled to the action capabilities of the body (see Proffitt, 2006, POPS, for a review). For example, reachable extents are perceived as a proportion of the maximum extent to which one can reach, and the apparent sizes of graspable objects are perceived as a proportion of the maximum extent that one can grasp (Linkenauger et al., 2009, JEP:HPP; Linkenauger, Ramenzoni, & Proffitt, 2010, Psychol Sci; Witt, Proffitt, & Epstein, 2005, JEP:HPP). Therefore, apparent distances and sizes can be influenced by changing the action capabilities of the body. In order to directly manipulate the perceived action capabilities of the body, participants were immersed into a full cue virtual environment. In real time, participants' hand, arm, and head movements were mapped onto a self-avatar which the participant viewed from the first-person perspective via a head-mounted display. To manipulate perceived action capabilities, the apparent size of the participants' hand was altered by decreasing or increasing the size of the self-avatar's virtual hand (small, normal, and large). Participants estimated the sizes of various objects in the virtual environment. Participants perceived objects to be larger when their virtual hand was smaller and perceived objects to be smaller when their virtual hand was larger. Consistent with the functional approach, the differences in apparent size across the conditions increased as a function of object size, suggesting changes in the scaling metric rather than a constant bias.