I can't sight-read, and I can't play by ear, so I sometimes jokingly say that I play 'by hand'. That's fairly apt though, because when I'm improvising/exploring it has a lot more to do with what feels right tactile-ly rather than auditorily. Obviously I still have a feedback loop of listening to whether what I'm playing sounds good, but it ends up being more of a filter steering me away from things that sound bad than a pull to what sounds good. It seems to me it's more the motor-control portion of my brain that's leading the way in improvisation.

Because of all this, I find it interesting when my hands 'want' to play something more difficult than they are (initially) capable of. In this songlet, I gravitated towards the trills, but they were at the edge of my ability to play well so I had to practice a decent bit to make them sound right in addition to feel right.