That we think slow. I've been self-teaching myself piano, and was talking to an opera singer once about how I find it hard to play with both hands (a common struggle for beginners) – she does too, as she only uses a piano sometimes to tune her voice during warmups. Anyway, she tells me "you've mentioned before that you stutter. Is it possible that you also have trouble processing or coordinating separate pieces of music with both hands? like, something to do with–" \*points at her temple\* "–the same part of the brain?"