Big Foot: Using the Size of a Virtual Foot to Scale Gap Width

Spatial perception research in the real world and in virtual environments suggests that the body (e.g., hands) plays a role in the perception of the scale of the world. However, little research has closely examined how varying the size of virtual body parts may influence judgments of action capabilities and spatial layout. Here, we questioned whether changing the size of virtual feet would affect judgments of stepping over and estimates of the width of a gap. Participants viewed their disembodied virtual feet as small or large and judged both their ability to step over a gap and the size of gaps shown in the virtual world. Foot size affected both affordance judgments and size estimates such that those with enlarged virtual feet estimated they could step over larger gaps and that the extent of the gap was smaller. Shrunken feet led to the perception of a reduced ability to step over a gap and smaller estimates of width. The results suggest that people use their visually perceived foot size to scale virtual spaces. Regardless of foot size, participants felt that they owned the feet rendered in the virtual world. Seeing disembodied, but motion-tracked, virtual feet affected spatial judgments, suggesting that the presentation of a single tracked body part is sufficient to produce similar effects on perception, as has been observed with the presence of fully co-located virtual self-avatars or other body parts in the past.