Abstract
Background: Fajen & Warren (JEP:HPP, 2003) modeled locomotor behavior as a dynamical system in which stationary targets and obstacles function as attractors and repellers of an agent's target-heading angle. Subsequent work extended this model to the case of a moving target (Warren & Fajen, Psychonomics 2002) or a moving obstacle (Warren, Sun, & Fajen, VSS 2003). Our purpose is to test whether these four components can be integrated into a general model of locomotor behavior. The present study examines intercepting a moving target in the presence of a stationary obstacle.
Research Question: Participants are asked to intercept a moving target when a stationary obstacle is placed in the vicinity of their interception path. We test model predictions about (1) when and where participants start to avoid the obstacle, and (2) under what conditions participants pass left or right of the obstacle.
Design: Testing is done in the VENLab, a 12 × 12 m virtual environment in which participants can walk freely. Participants wear a head-mounted display (60 deg H × 40 deg V) that presents a textured ground plane with colored poles that serve as obstacles and targets. Head position is recorded at 30Hz, and we analyze the 2D path and the time series of target-heading angle. The moving target's trajectory (90 deg (frontal plane) or 120 deg) and speed (.4, .5, .6 m/s) are varied, as is the presence of a stationary obstacle near the interception path.
Implications: This study is part of a research program to develop a general model of locomotor behavior that can predict human paths through complex environments. Such a model demonstrates that locomotor paths may emerge on-line from the interaction between an agent and a structured environment, rather than being explicitly planned.
NIH EY10923, NSF LIS IRI-9720327