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要旨

We investigated the role of global and local landmarks in the navigation of the `Hexatown' virtual environment (Gillner Mallot, 1998, Journal of Cognitive Neuroscience). Hexatown consists of a regular hexagonal grid of streets and junctions. Each junction was identified by the presence of distinct `local landmarks' (buildings, phone box, etc.). Additionally, global direction or compass information was provided by `global landmarks' (hilltop, television tower, and city skyline). According to subjects' movement-decisions, egomotion was simulated, and displayed on a 180-degree-projection screen. Subjects learned the route back-and-forth between two local landmarks. In the test-phase individual junctions were approached and the subject's movement-decision was recorded. We performed two experiments involving landmark changes after learning: In the first, we used conflicting cues by transposing landmarks. In the second experiment we reduced either local or global landmark information. Results show that both local and global landmarks are used in way-finding decisions. However, different subjects rely on different strategies. In the first experiment (cue conflict) for example, some of the subjects used only local landmarks while others relied exclusively on global landmarks. There were also subjects who used local landmarks at one location and global landmarks at the other. When removing one landmark type in the second experiment, the other type could be used by almost all subjects indicating that information about the neglected landmark type was present in memory.