[Avery Andrews 930212.11258]
(Bill Powers (930911.0700 MDT))
>I think you're forgetting about disturbances. Choice a) can't
>possibly work, because the initial conditions are never the same
No, I'm not forgetting about disturbances. What matters to get a
good hit is that the bat be in the right place, with the right
orientation, at the right time, moving in the right manner. This
can be achieved by getting the right trajectory of kinesthetic
perceptions from the joints. The CPG specifies the trajectories,
the the lower level systems produce them, dealing with the effects
of the uniform, arm musculature,
>They are quite distinct. Under the assumptions of choice a), two
>identical pitches will result in two identical swings of the bat
>The bat will hit the ball only if the batter and bat begin in
>exactly the same initial conditions each time, and if the muscle
Not if the CPG has parameters, so that it converts info about
(the beginning of) the pitch into appropriate kinesthetic reference
levels, so that it's a sort of transducer. Maybe VR experiments could
distinguish the possiblities: the trajectory of the virtual ball is
altered as it approaches the batter, and we see if any change in the
swing results. Incidentally, I find the watchability of a sport
inversely proportional to the plausibility of it involving CPGs, e.g.
Ice Hockey or soccer, quite watchable; golf, absolutely un.
>But all first order perceptions don't have control systems to
>control them: only certain of the kinesthetic perceptions and a
>very few others do, and then control is only in the dimension of
>intensity. Furthermore, control that requires more than one
>first-order control system (such as creating the sound of two
>hands clapping) requires control using two kinesthetic position
>control systems.
But if the perception is linear, you can still do it algebraically,
without 2nd order _control_ systems (2nd order would be feedforward).
But I'm sure the the 2nd order control systems will actually work
better, for the sorts of reasons you describe. Especially because you
can add an additional 2nd order system without altering the previously
existing ones, whereas a feedforward approach would require complete
rewiring of the whole system (I think). I hope this is the basic
point of what you say about evolution.
>The mere fact that people are able to control something only when
>others are trying to control a similar thing relative to a
>similar goal is not enough to establish the reality of group
>control systems. If you have an option as to whether to interpret
But that's not what I was trying to do. The stretcher bearers maintain
levelness against disturbances, so it looks like they are functionally
equivalent to a control system, so either a group is a control system
or a non-control system can do the same job as a control system. An
attendant issue is whether we want to recognize the pair of stretcher
bearers as an entity in our ontology - one certainly does in everyday
life (`stretcher team 3, get into Ambulance #6'), so it seems reasonable
to me to do so.
Returning to the main thread of the sophistry, it seems to me that organisms
might perfectly well contain groups of control systems related in a similar
way to the two stretcher bearers - maybe one system control the concentration
of enzyme A, keeping it at a reference level determined somehow or another,
while another system keeps the concentration of enzyme B at 1/2 that
of A. If there are groups of control systems in biochemistry, why not
psychology, etc.?
(Rick Marken (930911.0900))
>>Incidentally, my article contrasts Newell's view of how to
>>explain behavior with the Noam Chomsky's idea of a "competence" account.
>
>In what way does Chomsky's model of behavior differ from a behaviorist
>model (other than by the fact that he says that it does)?
Principally in that Chomsky doesn't have, and never has claimed to
have, any model of behavior. He has frequently argued that this is
a wildly overambitious aim, the causation of behavior being a
`mystery' rather than a `problem', in his terminology.
(Rick Marken (930911.1100))
>>This reminds me, Rick: Avery's date is frequently ahead of ours
>>by one day because he's across the International Date Line.
>
>I know and LOVE that fact. My crack about Australia was made when
>Avery mistyped the date so that it was a MONTH rather than a day
>off (I think he typed 930809 when it was 930908).
Actually, Australia is wierder than you think - down here we normally
write date/month/year rather than month/year/date. Reporting financial
transactions done in one country to the tax authorities in the other
is a real treat ...
Interesting observations about the water jar stuff.
Avery.Andrews@anu.edu.aung