The Role of Geographical Slant in VirtualEnvironment

for providing the VR{models used in this experiments. The authors thank Pavel Zahorik for comments and suggestions on an earlier draft of this manuscript. We are grateful to Scott Yu for providing the 3D model of our virtual environments lab shown in Fig. 1. Abstract. We have investigated the role of geographical slant in simple navigation and spatial memory tasks, using a computer graphics town called \Hexatown" (Gillner & Mallot 1998). This environment was a hexagonal grid of streets with landmarks placed in each angle between two streets. The whole environment could be slanted by an angle of 4. Three slant conditions were used: at: no slant; slanted NW: slant direction 30 Northwest with respect to some arbitrarily chosen \North"; slanted NE: slant direction 30 Northeast. Twelve subjects participated in each condition. Images were projected on a 180 half cylindrical projection-screen. Subjects could interact with the virtual environment by pedaling with force-feedback on a bicycle simulator (translation) or by hitting buttons (discrete rotations in 60 steps). Subjects explored the environment by searching 15 routes to various goals presented to them as pictures. After learning, spatial memory was accessed by three tasks, using an across subjects design: (i) pointing from various positions to the learned goals (19 pointings per subject); (ii) choosing the more elevated of two landmarks from memory in a forced choice paradigm; (iii) drawing a sketch map of the environment. The number of navigation errors (wrong motion decisions with respect to the goal) was strongly reduced (p < 0:001) in the slanted conditions. Furthermore, subjects were able to point to currently invisible targets in virtual environments. Adding a geographical slant improves this performance. Signiicant diierences (circular F-test) of the mean angular deviations between the \\at" and the two \slanted" conditions were found. There was also a signiicant diierence between the two slanted conditions (p < 0:01). We conclude that geographical slant plays a role either in the construction of a spatial memory, or in its readout, or in both. 1 Introduction \Navigation refers to the practice and skill of animals as well as humans in nding their way and moving from one place to another by any means. Generally moving from place to place requires knowledge of where one is starting, where the goal is, what the possible paths are, and how one is progressing during the movement" (Pick 1999). One source of information that may be salient …