Google has tweaked its “deep learning” AI to use an external memory bank. It’s an attempt to replicate the way human brains use short term memory to simplify reasoning.

The company demonstrated the approach by having the system teach itself the London Underground (subway) map and figure out the quickest route between stops. It’s a simple task to humans, but the process – which involves comparing multiple branching options with 270 stops over 11 lines – is exactly the type of problem that poses a challenge to artificial intelligence.

Because the system was allowed temporary access to stored memory, it was able to more effectively process and categorize the possible routes without having to start from scratch each time. That’s similar to how a human brain could use short term memory to filter down all the possible routes by ruling out every one that involves travelling in a particular direction from a specified stop, repeating the process until only the optimum answer remained.