I Will Choose "Free Will"
This is interesting for its implications with playing music, especially jazz. Everything we play is preceded by some brain activity micro-seconds before the conscious impulse to do it. Everyone is primed for musical ability, and those that develop it further have tapped into those more mysterious motivations. The Flow experience while playing music ("Caching") may mean that that Flow is over that whole range of "wills", not just the one we think is operating on the level of honed abilities.