Have you ever stood in front of a subway map in a big city, completely perplexed and unable to plan your route, especially if it required several connections? According to new research at Oxford University, there’s nothing wrong with you. The system may be too complex for human minds.
For the study, a team of physicists and mathematicians found that most big-city transportation systems do, in fact, exceed human cognitive abilities, particularly when the rider needs to plan out a complex trip which would require at least two connections.
“Human cognitive capacity is limited, and cities and their transportation networks have grown to the point where they have reached a level of complexity that is beyond human processing capability to navigate around them,” said Dr. Mason Porter, professor of nonlinear and complex systems in the Mathematical Institute at the University of Oxford.
“In particular, the search for a simplest path becomes inefficient when multiple modes of transport are involved and when a transportation system has too many interconnections. There are so many distractions on these transport maps that it becomes like a game of ‘Where’s Waldo?’” said Porter.
Using journeys with exactly two connections as their basis (that is, visiting four stations in total), the researchers found that navigating transportation networks in major cities can most definitely push the limits of humans’ cognitive powers.
As part of the study, the researchers wanted to determine at which point the complex urban transport system surpasses the limits of human cognition.
After analyzing the 15 largest metropolitan transport networks in the world, the researchers estimated that the information limit for human brains in planning a trip is around eight bits. (A ‘bit’ is a binary digit, the most basic unit of information.) This eight bit limit is similar to the “Dunbar number,” which estimates a limit to the size of an individual’s friendship circle.
Based on this eight bit limit, the researchers say that transportation maps should consist of no more than 250 connection points overall. Furthermore, when multiple interchanges or other modes of transport such as buses or trams are added to the route, the complexity of networks can rise well above the eight bit threshold. The researchers demonstrated this using the multimodal transportation networks from New York City, Tokyo and Paris.
“Put simply, the maps we currently have need to be rethought and redesigned in many cases. Journey-planner apps of course help, but the maps themselves need to be redesigned. We hope that our paper will encourage more experimental investigations on cognitive limits in navigation in cities,” says Porter.
Source: University of Oxford