Beyond the Periphery: Child and Adult Understanding of World Map Continuity

It is well established that map projections make it difficult for a map reader to correctly interpret angles, distances, and areas from a world map. A single map projection cannot ensure that all of the intuitive features of Euclidean geometry, such as angles, relative distances, and relative areas, are the same on the map and in reality. This article adds an additional difficulty by demonstrating a clear pattern of naïveté regarding the site at which a route that crosses the edge of a world map reappears. The argument is that this naïve understanding of the peripheral continuation is linear, meaning that the proposed continuation is along the straight line that continues tangentially to the original route when it crosses the edge. In general, this understanding leads to an incorrect interpretation concerning the continuation of world maps. It is only in special cases—such as radial routes on a planar projection and peripherally latitudinal routes on a cylindrical or pseudocylindrical projection with a normal aspect—that the actual peripheral continuation of the world map is linear. The data used in this article are based on questionnaires administered to 670 children aged nine to fifteen and eighty-two adults. This naïve understanding of the peripheral continuation, which leads to errors, was found to be entirely dominant among the children, regardless of the projection, and was clearly observed among the adults when the projection was cylindrical with a normal aspect.