Limb movements of another pedestrian affect crossing distance but not path planning during virtual over ground circumvention

Abstract

Circumventing another pedestrian is a frequent daily activity. The literature has provided a better understanding about anticipatory locomotor adjustments based on global (whole body) movement, but how local limb movements of another pedestrian affect one's circumvention is not well known. The purpose of this study was to understand how local limb movements of another pedestrian affect the planning and execution to circumvent them. Ten healthy young adults (24.5 ± 3.0 years) were immersed in a virtual environment representing a shopping mall. Participants walked to a shop located directly in front of them while circumventing a virtual agent which, when present, approached from straight ahead with one of four different locomotor patterns: 1-Normal locomotor movements; 2- No arm movements; 3- No leg movements; 4- No arm and leg movements (gliding to them). Circumvention trajectory, minimum clearance and coordination of head and trunk rotations along with center of mass lateral displacement were examined. Nonparametric Analysis of Longitudinal Data was used to compare variables across the different conditions. Minimum clearance was smaller for normal locomotor movements compared to all other conditions, but coordination of body movements and onset of circumvention trajectory deviations remained unchanged. These results suggest that global body movement is sufficient to plan circumvention trajectories in a predictable avoidance task, but clearance safety margins are influenced by the local limb movements of another pedestrian.

Keywords: Circumvention; Gaitt; Locomotion; Navigation; Obstacle avoidance; Virtual reality.