title: Lost in transportation: Information measures and cognitive limits in multilayer navigation.
abstract: Cities and their transportation systems become increasingly complex and multimodal as they grow, and it is natural to wonder whether it is possible to quantitatively characterize our difficulty navigating in them and whether such navigation exceeds our cognitive limits. A transition between different search strategies for navigating in metropolitan maps has been observed for large, complex metropolitan networks. This evidence suggests the existence of a limit associated with cognitive overload and caused by a large amount of information that needs to be processed. In this light, we analyzed the world's 15 largest metropolitan networks and estimated the information limit for determining a trip in a transportation system to be on the order of 8 bits. Similar to the "Dunbar number," which represents a limit to the size of an individual's friendship circle, our cognitive limit suggests that maps should not consist of more than 250 connection points to be easily readable. We also show that including connections with other transportation modes dramatically increases the information needed to navigate in multilayer transportation networks. In large cities such as New York, Paris, and Tokyo, more than 80% of the trips are above the 8-bit limit. Multimodal transportation systems in large cities have thus already exceeded human cognitive limits and, consequently, the traditional view of navigation in cities has to be revised substantially.
authors.affiliation: Institut de Physique Théorique, CEA-Saclay, Gif-sur-Yvette F-91191, France.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Gallotti
authors.affiliation: Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK.; CABDyN Complexity Centre, University of Oxford, Oxford OX1 1HP, UK.
authors.forename: Mason A
authors.initials: MA
authors.lastname: Porter
authors.affiliation: Institut de Physique Théorique, CEA-Saclay, Gif-sur-Yvette F-91191, France.; Centre d'Analyse et de Mathématique Sociales, École des Hautes Études en Sciences Sociales, 190-198, Avenue de France, 75244 Paris Cedex 13, France.
authors.forename: Marc
authors.identifier: 0000-0003-0890-9713
authors.initials: M
authors.lastname: Barthelemy
mesh_terms: D002947:Cities; D003071:Cognition; D006801:Humans; D008960:Models, Psychological; D008962:Models, Theoretical; D009518:New York; D010297:Paris; D014041:Tokyo; D014186:Transportation; D014505:Urban Population
keywords: mutlilayer networks; networks; transportation; urban navigation