guitarrista wrote: ↑
Tue Nov 21, 2017 4:48 pm
Rasputin wrote: ↑
Mon Nov 20, 2017 10:15 pm
guitarrista wrote: ↑
Mon Nov 20, 2017 7:14 pm
I personally dislike using the single gesture/compound [single] stroke terminology because I see it as potentially confusing matters. What that is referring to is conscious versus subconscious control; however when we execute a series of movements subconsciously they are still individual (i.e. not synchronous but separated in time) movements, just not individual conscious movements.
Yes, the distinction exists at the level of unconscious initiation of the motor program, and at the level of conscious command, but not usually at the level of the muscles. We live at the level of conscious command, so I still think there is a place for it - we just have to remember that at some point in the chain, it is broken down into individual tasks.
I think where we differ is when you say "not usually at the level of the muscles". The motor program is still a series of separate commands driving separate muscles or muscle bundles in some memorized and internalized sequence; hence I don't like it being called a single gesture or stroke. As an easy example, consider fast i-m alternation at tempo 150x4 or faster. Even if you are convinced that the flexor muscle activation is the same command for both i and m (I don't since we have individual control over these fingers, but let's skip over that), there is an alternation of flexor, extensor, flexor, extensor for each i-m-i-m set, done subconsciously at that speed. ("Passive return" is not fast enough to accomplish the finger reset for its next stroke at that speed). Or perhaps I've misinterpreted your view on this.
What I meant is that it may often make sense to draw a distinction between single commands and bundled commands at the level of unconscious initiation of the movement, and at the level of the perceived command, but it will only rarely make sense at the level of the individual muscles, because the command is almost always individualised by that point. I agree that in the case of im alternation, there are individual commands arriving at the muscles controlling i and m. I think that must be so even if the flexor is shared, because that would mean that flexing i by itself involves contracting the shared flexor while simultaneously contracting an extensor that acts on m but not i. The exception I had in mind (I wrote ma when I should have written am) was where you flex a and m comes along for the ride. In that case you have one muscular contraction bringing about two strokes, and in that sense there is bundling even at the muscular level.
A motor program has to consist of individual commands, I agree – but to call it a program is not to deny that so much as to suggest that, for the purpose at hand, it is more useful to look at it as one bundle. I suspect we agree on that and your point is that once we get down to the level of the muscles, it is no longer useful to look at them as a bundle. That is exactly what I was trying to say though.
I am starting to think that the idea of bundling is quite useful. I’m not sure I really follow Berg’s logic when he relates it to feedback time, because I can’t see how bundling instructions reduces feedback time. It does make sense though if you assume that HQ (wherever we consider that to be) can only give so many commands per unit of time, but that its minions can handle a lot more. If HQ’s instructions are to carry out pre-prepared bundles of commands, rather than individual ones, it can get more commands executed in the same time. This suggests that we need to spend practice time making up our bundles (I guess through slow/fast practice). I have a hunch that we are better off putting tricky bits in the middle of a bundle, but I haven’t rationalised that yet. I am well into the realm of speculation here, but then so is Berg, and his version doesn’t even seem to make sense.