The Role of Geographical Slant in Virtual Environment Navigation Sibylle

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. Signi cant di erences (circular F-test) of the mean angular deviations between the \ at" and the two \slanted" conditions were found. There was also a signi cant di erence 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.