Road climbing: Principles governing asymmetric route choices on maps

The focus of this paper was on how people plan routes when using maps. This issue is relevant not only to the design of maps, but also to the construction of new navigation systems built to help people plan routes. The research was concerned with the principles that people follow when selecting a route. Specifically, the authors investigated why people's route choices are often asymmetric - why a different route is chosen when traveling between two locations depending on which point is the origin and which is the destination. It is contended that this path asymmetry does not occur randomly; subjects' route selection is systematic and predictable. Often, subjects will employ a heuristic termed here as road climbing, which is similar to hill climbing strategies used in problem-solving. Road climbing is a preference for long and straight routes in the local area containing the origin. In Experiment 1, subjects chose paths predicted by a road climbing model even when the selected paths were 50 per cent longer than alternative paths. Moreover, this effect was exaggerated when subjects processed the maps on a region-by-region basis. In Experiment 2, the results were extended to include real maps that subjects may encounter in their day-to-day routines. These results are discussed in terms of their relevance to current problem-solving and spatial cognition research. Practical applications are also considered.