Throwing vs. walking as indicators of distance perception in real and virtual environments

In order for humans to act effectively in their environment, it is important for the visual system to determine the absolute size and distance of objects. Some measures of distance perception, characterized as visually directed walking tasks [Rieser et al. 1990; Loomis et al. 1992], indicate that humans are good at solving this problem given distances ranging from 2 to 25 meters in full-cue real-world environments. One example of this type of task is direct blind walking, in which observers walk without vision to previously viewed targets on the ground. Despite accurate behavior in the real-world, recent research in immersive virtual environments (VEs) using head-mounted displays (HMDs) has consistently found compression of distance to targets on the floor given the same blind walking tasks [Loomis and Knapp 2003; Thompson et al. in press].