VOR as Open-Loop?

[from Gary Cziko 931114.1646 GMT]

Bill Powers (931112.0815 MST) said:

The main issue we have to clear up is whether a purely open-loop
model is EVER a plausible representation of the mechanisms of
behavior.

Bill, wouldn't you agree that the vestibulo-ocular reflex (VOR) is a good
candidate for purely open-loop behavior, given that there appears to be no
non-visual feedback concerning the position of the eyes?

It would be interesting to use Rick Marken's test for open-loop behavior on
the VOR. If it passed, then we could point with confidence to one example
of open-loop behavior and it wouldn't appear that we were dismissing out of
hand all S-R models of behavior. The trouble is finding a way to attach
rubberbands to the eyeball to see if it resists disturbances!

Then we could invite others to find any other open-loop behaviors. Perhaps
the VOR is the only one. It's hard to imagine any other behavior that is
so removed from disturbances as the eyeball movements.--Gary

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[From: Bruce Nevin (Mon 931115 08:25:52 EST)]

Gary Cziko 931114.1646 GMT

The trouble is finding a way to attach
rubberbands to the eyeball to see if it resists disturbances!

Then we could invite others to find any other open-loop behaviors. Perhaps
the VOR is the only one. It's hard to imagine any other behavior that is
so removed from disturbances as the eyeball movements.

When I started thinking about disturbances to speech I considered the
difficulty of introducing disturbances manipulated by the experimentor
and neglected the possibility of other naturally occurring disturbances
that might be measured and experimentally observed to be resisted.
Perhaps you are doing the same? Muscle fatigue is an obvious
naturally-ccurring disturbance that Bill has mentioned from time to time.
How hard is it to meter? Electromyography can give an idea of something
like effort or magnitude of neural signals to muscles as a variable. If
this signal varies with no observed difference in movement, a disturbance
can be inferred.

The muscle pulses involved in phonation (movements of the bones and vocal
bands in the larynx during voice production) seem pretty protected from
experimentor-manipulable error. Various impediments to speech can be
introduced in the mouth, but how to make these gradual and metered
variables I don't yet know.

    Bruce
    bn@bbn.com