Two years ago I discovered that if I walked while studying Chinese flashcards (using Anki), both activities — walking and studying — became easier. I could walk much longer on my treadmill and I could study much longer. Walking made studying more pleasant and vice-versa. Around the same time, Jeremy Howard, the president of Kaggle, made the same discovery independently. In an email to me, he writes:
I came up with the idea accidentally a couple of years ago – I needed to go to the gym every day, and that included 30 minutes on a cross-trainer (but I only managed to do 15 min most days). I needed something to do to keep me amused, so I brought along my PC and started doing my Anki whilst on the cross-trainer. I discovered I could do my cross-trainer for at least twice as long, and my Anki results were better too. Later I added treadmill walking to my Anki study too.
He says more about it, including how much it helped him, in a QS talk.
As Nabokov says in Pale Fire,
If on some nameless island Captain Schmidt
Sees a new animal and captures it,
And if, a little later, Captain Smith
Brings back a skin, that island is no myth.
Learning methods that use this effect are going to have a big advantage over learning methods that don’t.