How skilled are London taxi drivers at learning routes through unfamiliar towns?

London taxi drivers have to undertake years of intense training known as 'the knowledge' to gain their operating licence, including learning the layout of over 25,000 of the city's streets. A new study by Katherine Woollett and Eleanor Maguire asks whether their expertise will generalise to skilled way-finding in new situations. The answer is far from obvious given that previous research using 'table-top' tests of visuospatial memory have actually found taxi drivers to perform worse than controls, almost as if their London expertise comes at a cost. Incidentally, Maguire is the psychologist who brought us the famous 'cab drivers have enlarged hippocampi' study (pdf).

Twenty male London taxi drivers and 18 IQ-matched male controls (London residents) watched four repeats of a five minute video of two unfamiliar routes through a town in Ireland. Afterwards all the participants completed several tests of their knowledge of the new routes, including looking at photos of buildings and other scenes and saying which route, if any, the photo came from; making judgments about the relative proximity between landmarks; and sketching out a map of the routes. The important finding here was that the two groups performed equally on their categorisation of the street scenes and their proximity judgments, but that the taxi drivers were substantially better at navigating new routes within and across the two areas, and were superior at sketching out the routes with a pencil and paper.

'Taxi drivers undergo years of training ... Similarly in their job, day in day out, they are required to plan and execute routes,' the researchers said. 'Clearly these general attentional, learning and memory mechanisms are finely-tuned and readily called upon when they are required to learn a new town.'

However, it wasn't all good news for the cab drivers. A second investigation tested their ability to learn unfamiliar routes (taken from Bath and featuring similar architecture) that were integrated into familiar areas of London. At this task, the taxi drivers struggled compared with their performance when learning entirely new routes. Woollett and Maguire speculated that in this case the drivers' expertise was getting in the way of learning the new routes: 'When presented with new information to learn that is similar to their existing knowledge, their poorer performance may reflect expert inflexibility and an inability to inhibit access to existing (and now competing) memory representations.'

This finding tallies with the real-life experiences of taxi drivers. For example, several of them reported struggling a few years ago to incorporate new layouts around the Canary Wharf district into their existing knowledge.

The issue of why taxi drivers struggle at 'table-top' tests of visuospatial memory (as shown in earlier research), such as reproducing a complex drawing from memory, remains unexplained.
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Woollett, K., and Maguire, E. (2010). The effect of navigational expertise on wayfinding in new environments. Journal of Environmental Psychology, 30 (4), 565-573 DOI: 10.1016/j.jenvp.2010.03.003

Previously on the Digest: How to give directions.