[From Rick Marken (960714.1420)]
Hans Blom (960712) --
Well, let me try again. I seem not able to make myself clear.
Have you considered the possibility that you are making yourself
perfectly clear?
Hans Blom (960712) --
I kind of like well-phrased withering sarcasm, but not if it is based
on misunderstandings and attacks a straw man. Well-phrased it was.
Straw man, too. Remember that you said it can't be done? I said it
can. Bill said it's different. I agree with that.
When I said that threading a needle blindfolded can't be done, I meant
that it can't be done as needle threading is normally done; in a reasonable
amount of time with assurance of success. Give a few hours in the
dark I'm sure I could thread a needle; but after a few billion years a
monkey at a typewrite could write the preface to B:CP too. Wouldn't it
be a bit gratuitous for me to have said that a monkey at a typewriter
_could_ write the preface to B:CP if you had said it couldn't?
There was no straw man in Bill's comments. If you actually agreed that
threading a needle blindfolded is done in a completely different way
compared to threading it with eyes open, then you would have objected
strongly when Bill said (sarcastically).:
So Hans, you are absolutely right. There is no difference between
threading a needle with your eyes open and threading it with your eyes
closed.
But you responded to the post as though Bill were actually agreeing with
you. Bill (and I) assumed (correctly, I believe, given your reply to Bill's
sarcasm) that you were saying that people _can_ thread needles blindfolded
because they produce a threaded needle by generating outputs open loop
based on a model of the environmental circumstances in which threading
takes place. This assumption was confirmed even more strongly when
you failed to protest Bill's most sarcastic comment of all:
The model that is used by the control system simply generates
the same outputs it normally generates, and since they produce needle-
threading movements when your eyes are open, they also produce needle-
threading movements when your eyes are closed.
Both Bill and I think you actually believe this (and since you didn't
see this as a joke it seems likely that you do believe it) because you
are always talking about how the model-based controller is the best
model of ordinary behavior because people don't really need to rely
on their perceptions in order to control. In other words, you continue
to argue for a model-based control of output model of behavior as though
there were tons of evidence for such a model. In fact, there is not a speck
of evidence for such a model; the only thing going for the model-based
control model is that many conventional control engineers, roboticists and
psychologists believe in it.
Bill's point in the post about Mary's ability to thread the needles with
eyes closed was that there is, in fact, no evidence _at all_ that people
generate the same outputs in order to produce the same result blindfolded
versus with eyes open. When Bill said "the model that is used by the
control system simply generates the same outputs it normally generates"
he was being sarcastic -- big time!
In fact, what Mary's data show is that people have to learn to control
different perceptions when the perceptions that are usually controlled
are no longer available. Blind people can thread needles because they
know how to control kinesthetic and touch sensations properly in
order to produce the objective result "threaded needle". Mary's data was
not evidence of "model based" control; in fact, it was a solid rejection
of model based control.
The needle threading data (blindfolded and not blindfolded) is another
powerful demonstration that behavior (the production of desired results
like threaded needles) is the control of perception.
Best
Rick