by SIMON ROBERTS, Stripe Partners Today I turned left out of London Bridge station. I usually turn right and take the Tube but instead I went in the other direction and took the bus. I can’t explain why I did that. Perhaps I was responding to a barely discernible change in crowd density or the fact that it was a bit warm today and I didn’t want to ride the Tube. Either way, I was trusting instincts that I am not able to translate into words. Often when I travel around London I reach for the CityMapper app. I rely on it to tell me how best to get from A to Z but I don’t really know how it makes the recommendations it does. Likely it has access to information about the performance of the Tube today or real time knowledge of snarl-ups on London’s medieval roads. It’s clever and I love it. It knows more than I do about these things and what to do about them. The workings of CityMapper are a mystery to me—but so are the workings of my brain. Even if I had a sophisticated understanding of neuroscience, physiology...