I do a form of this all the time and I've always wondered "how." I can copy Morse Code--hearing the code and writing it down--while carrying on a conversation with someone else. I'm only "encoding" it, in that I have to read it to know what I just copied. The process of hearing a letter or word in Morse and moving my hand to write it has become so automatic that I can do it while having a live conversation with someone in the room.

It would be interesting to know what's going on in my head with an EEG or FMRI...