[dfan]

I did some moderately serious dual n-backing a year or so back in an effort to improve my chess game. Of course it wasn't a remotely scientific experiment so I can't tell if it really helped, but I did feel that my ability to concentrate increased, if not my ability to reason. I felt more able to take a breath after working out a variation and take a few seconds to really concentrate on the final (imagined) position and scrutinize it for tricks.

(My USCF rating did go up fairly significantly around then but it's no proof of any causation, plus I was doing plenty of other things at the same time to increase my chess results anyway.)

[marquis]

I feel the same way while learning a new technique on an instrument. It's having that focus and attention to detail that you can draw upon in your work when you need it.