Transport makes cities: transit maps as major cognitive frames of metropolitan areas.

Spatial representations play a fundamental role in navigation, decision-making, and overall interaction with our environments. Understanding how individuals construct and use them holds significant importance in spatial cognition research, and even bears practical implications for urban planning as it can explain how we interact with the spaces we inhabit. In large urban areas, transit maps stand as prominent visual aids, guiding people through public transportation systems. These maps, while designed for navigational purposes, may influence how individuals perceive and represent their cities. For instance, Vertesi (Social Studies of Science 38:09-35, 2008) showed through a series of interviews including a "sketch mapping" phase, that London Tube Map seems to structure residents' spatial representation of their city. However, thorough quantitative research on this subject have not been carried out yet. Two experimental studies have been conducted to demonstrate how residents' representations of metropolitan areas closely resemble the schematic representations of their public transport networks. First, we show that residents of Greater Paris-public and private transport users alike-plot city landmarks in a layout more closely resembling that of the Parisian transit map than the geographical map. Next, we asked Greater Berlin, London and Paris residents to place landmarks of their cities on different map backgrounds. A similar procedure was followed for landmarks from an unknown city, after a dedicated learning phase. For known cities, the sketch maps produced were closer to transit maps than to the geographical ones, although less so if the test map background presented topographical elements (e.g., rivers, etc.). For learnt cities, participants' sketch maps were almost exclusively dependent on the map provided during the learning phase. These results suggest that familiarity with transit maps has a direct impact on the metric properties of spatial representation in memory, a phenomenon we propose to call the 'schema effect'.