This website is now archived. While it is fully functioning, I no longer maintain it and comments are turned off on most posts. Please visit the updated

The Knowledge of London Cab Drivers

‘Patient TT’ is a London Black Cab driver who has suffered Hippocampus damage on both sides of his brain after a brain infection. This may strike you as odd if you’ve heard that London Black Cab drivers have enlarged Hippocampi – a part of the brain that helps with memory and spatial navigation. Patient TT can still navigate around London and does not seem to have lost ‘The Knowledge’. This is according to a recent study that I came across over at MindHacks.

What really struck me as amazing however, was what ‘The Knowledge‘ actually is – it is the test all London cab drivers must pass in order to get a licence to operate in the city, and is the world’s most demanding training course for cab drivers, taking an average of 12 sittings and 34 months of preparation!

They must know the 320 ‘standard routes’ through central London, over 25,000 streets and all places of interest on each of these roads. It is worth noting however, that by ‘places of interest’ The Knowledge refers to clubs, hospitals, hotels, theatres, government and public buildings, railway stations, police stations, courts, diplomatic buildings, important places of worship, cemeteries, crematoria, parks and open spaces, sports and leisure centres, places of learning, restaurants and historic buildings. Now that is a lot of places, and a very daunting task… all before you hear that they must know the order of every theatre on Shaftesbury Avenue – the central street in London’s theatre district!

As for the test itself, the prospective cab drivers must first pass a written test allowing them to proceed to the final, and incredibly difficult, oral examination. It is here where they must, without looking at a map, identify the quickest and most sensible route between any two points in metropolitan London that their examiner chooses. For each route the applicants must recite the names of the roads used, when they cross junctions, use roundabouts, make turns, and what is alongside them at each point.”

Next time I’m in London I’m definitely going to have a different experience when I jump in a cab.

As for Patient TT, it is believed that his ability to navigate London’s streets was not impaired by his brain damage, as throughout his life as a cab driver, his Knowledge became semantic. That is, he no longer had to ‘think’ of routes, destinations, and places of interest, as the repetition meant these things became ‘second nature’ to him. It’s the difference between me ‘just knowing’ that London is the capital of the United Kingdom and me knowing that Ulaanbaatar is the capital of Mongolia because I found this out recently whilst reading a book on the country.