5 ms·

A study came out in 2000, back when I was driving a taxi, showing that London cabbies with "the Knowledge" had changes to their brain anatomy.[0] My girlfriend

A study came out in 2000, back when I was driving a taxi, showing that London cabbies with "the Knowledge" had changes to their brain anatomy.[0] My girlfriend at the time spotted it in a college course and showed it to me. I remember her joking that she was only with me for the size of my hippocampus. I would hypothesize that it's more related to spacial/geographic memory than simply navigating spaces one visually perceives. My guess is the effect would be much less pronounced in people who drive for a living now relying on GPS maps. London taxi drivers, apparently, still must pass the notoriously difficult Knowledge test.[1] A similar (but less rigorous) test was required for Los Angeles cab drivers when I drove. And of course, if you weren't familiar with the street where your next call was (or where your passenger wanted to go), you had only seconds at a red light to leaf through the enormous Thomas Guide and memorize how you would get there.[2] [0] https://www.pnas.org/doi/full/10.1073/pnas.070039597 https://www.pnas.org/doi/full/10.1073/pnas.070039597 [1] https://london-taxi.co.uk/the-knowledge/ https://london-taxi.co.uk/the-knowledge/ [2] https://archive.org/details/losangelescounty0000thom/page/n9/mode/2up https://archive.org/details/losangelescounty0000thom/page/n9...

dang 2y ago
There have been a few HN threads about that over the years—here are some (I think there may be others?) Streetwise (1996) – BBC doc about The Knowledge (memorising every London street) - https://news.ycombinator.com/item?id=26581295 https://news.ycombinator.com/item?id=26581295 - March 2021 (1 comment) The Knowledge of London for cab drivers - https://news.ycombinator.com/item?id=25485509 https://news.ycombinator.com/item?id=25485509 - Dec 2020 (45 comments) The Guardians of London's Black Cab 'Knowledge' - https://news.ycombinator.com/item?id=10717003 https://news.ycombinator.com/item?id=10717003 - Dec 2015 (20 comments) London’s Legendary Taxi-Driver Test Puts Up a Fight in the Age of GPS - https://news.ycombinator.com/item?id=8585781 https://news.ycombinator.com/item?id=8585781 - Nov 2014 (105 comments) World's Hardest Geography Test - https://news.ycombinator.com/item?id=8306536 https://news.ycombinator.com/item?id=8306536 - Sept 2014 (1 comment) For London's Cabbies, Job Entails World's Hardest Geography Test - https://news.ycombinator.com/item?id=8295264 https://news.ycombinator.com/item?id=8295264 - Sept 2014 (68 comments)
- liontwist 2y ago
  I think it’s also in a Malcom gladwell book.
yieldcrv 2y ago
I would hypothesize thats its related to getting ousted from the job as a taxi driver if you have just early Alzheimer’s meaning no cognitive benefits from just navigating around a city more often
- LorenPechtel 2y ago
  That wouldn't surprise me in the least. Beyond the basic health things (weight, activity, smoking, diet, blood pressure) just about everything that they come up with that relates to living longer could also be filtering. I remain unimpressed because of this.
- robwwilliams 2y ago
  Brilliant comment—-The effect could easily be an ascertainment bias that is downstream of winnowing 55-70 year-old drivers who cannot hack route selection effectively anymore. They drop out and take on other jobs.
  - noduerme 2y ago
    I'm not so sure. The study didn't stipulate that taxi driving was the patient's last occupation, nor how long they did the job for. Also, with Alzheimers, aren't older memories the last to go? A driver would probably be more likely to have trouble finding their keys before they forgot the streets they'd been driving for 30+ years. At that point, it would be hard to train for another job. Additionally, I've never heard of a cab driver losing their license for getting confused en route. Taking the wrong way on purpose can lead to some disciplinary action, but even that is rarely if ever pursued.
    - robwwilliams 2y ago
      I am not sure either. The authors (more correctly, the author of the review of the the parent paper) imply that the constant challenges to adapt to complex spatial navigational tasks is the most likely explanation. Familiarity with routes is not the key variable (no bus driver benefit). It is active navigational adjustment or perhaps just ascertainment. Controlling for ascertainment bias would be possible but hard because you would face secular confounds (e,g., impact of COVID-19 on taxi drivers vs other professions). By the way, the original l”London taxi drivers have larger hippocampii paper” was NOT replicated. So sad since this is such a fun story.
alsetmusic 2y ago
A friend had a job installing security equipment and kept Thomas Guides in his car. This is only the second time I’ve seen the name. I’m so glad to live now, as I used to get very lost before GPS.

dang 2y ago

There have been a few HN threads about that over the years—here are some (I think there may be others?) Streetwise (1996) – BBC doc about The Knowledge (memorising every London street) - https://news.ycombinator.com/item?id=26581295 https://news.ycombinator.com/item?id=26581295 - March 2021 (1 comment) The Knowledge of London for cab drivers - https://news.ycombinator.com/item?id=25485509 https://news.ycombinator.com/item?id=25485509 - Dec 2020 (45 comments) The Guardians of London's Black Cab 'Knowledge' - https://news.ycombinator.com/item?id=10717003 https://news.ycombinator.com/item?id=10717003 - Dec 2015 (20 comments) London’s Legendary Taxi-Driver Test Puts Up a Fight in the Age of GPS - https://news.ycombinator.com/item?id=8585781 https://news.ycombinator.com/item?id=8585781 - Nov 2014 (105 comments) World's Hardest Geography Test - https://news.ycombinator.com/item?id=8306536 https://news.ycombinator.com/item?id=8306536 - Sept 2014 (1 comment) For London's Cabbies, Job Entails World's Hardest Geography Test - https://news.ycombinator.com/item?id=8295264 https://news.ycombinator.com/item?id=8295264 - Sept 2014 (68 comments)

liontwist 2y ago
I think it’s also in a Malcom gladwell book.

yieldcrv 2y ago

I would hypothesize thats its related to getting ousted from the job as a taxi driver if you have just early Alzheimer’s meaning no cognitive benefits from just navigating around a city more often

LorenPechtel 2y ago
That wouldn't surprise me in the least. Beyond the basic health things (weight, activity, smoking, diet, blood pressure) just about everything that they come up with that relates to living longer could also be filtering. I remain unimpressed because of this.
robwwilliams 2y ago
Brilliant comment—-The effect could easily be an ascertainment bias that is downstream of winnowing 55-70 year-old drivers who cannot hack route selection effectively anymore. They drop out and take on other jobs.
- noduerme 2y ago
  I'm not so sure. The study didn't stipulate that taxi driving was the patient's last occupation, nor how long they did the job for. Also, with Alzheimers, aren't older memories the last to go? A driver would probably be more likely to have trouble finding their keys before they forgot the streets they'd been driving for 30+ years. At that point, it would be hard to train for another job. Additionally, I've never heard of a cab driver losing their license for getting confused en route. Taking the wrong way on purpose can lead to some disciplinary action, but even that is rarely if ever pursued.
  - robwwilliams 2y ago
    I am not sure either. The authors (more correctly, the author of the review of the the parent paper) imply that the constant challenges to adapt to complex spatial navigational tasks is the most likely explanation. Familiarity with routes is not the key variable (no bus driver benefit). It is active navigational adjustment or perhaps just ascertainment. Controlling for ascertainment bias would be possible but hard because you would face secular confounds (e,g., impact of COVID-19 on taxi drivers vs other professions). By the way, the original l”London taxi drivers have larger hippocampii paper” was NOT replicated. So sad since this is such a fun story.

alsetmusic 2y ago

A friend had a job installing security equipment and kept Thomas Guides in his car. This is only the second time I’ve seen the name. I’m so glad to live now, as I used to get very lost before GPS.