Abstract
When a walker is faced with two competing goals, what determines route selection? Fajen & Warren's (2003) steering dynamics model suggests that relative distance and eccentricity should trade off in influencing the locomotor path. We presented participants with two stationary goals of equal valence but varying distance and eccentricity, and asked them to walk to the goal(s) as quickly as possible. The study was conducted in the Virtual Environment Navigation Lab, a 12m × 12m ambulatory virtual environment with a head-mounted display (60° H × 40° V) and a hybrid sonic/inertial tracking system (latency 50–70 ms). The goal objects were blue textured posts. In control trials, the two goals appeared at the same distance and the same target-heading angle (left/right) from the participant's initial heading. In experimental trials, one goal remained in the control position while the initial distance or target-heading angle of the other was manipulated. Preliminary results indicate that, on control trials, participants walk to one goal rather than between them, indicating a nonlinear competition between two goals. On experimental trials, when the initial target-heading angles are equal, participants walk to the closer goal; whereas when their initial distances are equal, they walk toward the goal with the smaller target-heading angle. These two variables appear to trade off. We seek to model these effects by elaborating a nonlinear steering dynamics model. Further experiments will investigate how an obstacle positioned in front of two competing goals influences route selection.