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Abstract:
Hierarchical theories of spatial memory propose that information about space is represented in nested levels of detail. Depending on physical properties and subjective evaluation of space, places are grouped together to regions. Such a spatial memory structure containing multiple levels of detail can be described as a graph containing basic and super ordinate nodes. Up to now support for the hierarchical theories came from distorted distance- and direction-judgments across regions as well as from priming effects and memory recall procedures in regionalized spatial layouts. To test the influence of regionalized spatial memory on navigation, we conducted an experiment using a virtual reality setup with a large half-cylindrical projection screen. Subjects navigated through a virtual environment that consisted of two islands that were interconnected by three bridges. Each of the islands carried six unique places that could be identified by their associated landmark; the islands ought to establish different regions in memory. Subsequent to an exploration- and learning-phase subjects were asked to navigate the shortest route connecting two of the places within the environment. The results reveal significant effects of the islands on route-planning when starting place and target place were located on different islands. If multiple paths with equal path length were available, subjects preferred the path with fastest access to the goal region with a frequency of over 70. These results are in line with a different series of experiments in which subjects minimized the number of region crossings in multi-goal navigations. Our results provide evidence from navigation experiments, supporting the hierarchical theories of spatial representations. We propose simple planning heuristics that make use of higher level structures of spatial memory and therefore allow minimizing computational effort when planning a route.
