ABSTRACT

In a perception-action coupling perspective, virtual environment technologies are often used to evidence the influence of visual information on human locomotion patterns (e.g., Bardy et al., 1996; Warren et al., 2001). For example, walking is influenced by optical flow velocity: With large velocities, human participants tend to decelerate their preferred walking speed (Prokop et al., 1997) or transition to the running pattern earlier (Mohler et al., 2004). The laws of control suggested by Gibson (1979) and formalized by Warren (1988) perfectly capture this interelation: Forward forces applied onto the ground surface create an optical flow at the observation point which contains relevant structure (e.g., expansion, motion parallax) that can in turn be used to modulate the free parameters of the action system.