[Martin Taylor 2004.01.02.1621]
From [Marc Abrams (2004.01.02.1309)]
> [Martin Taylor 2004.01.02.1016]
In standard PCT, an elementary control unit (ECU) consists of one
simple loop in which all signals are SCALAR variables.
OK. I assume by 'standard' you mean B:CP exclusively, correct?
B:CP and the generally accepted results of discussions on CSGnet over
the dozen years I've been reading it.
The output signal may be distributed to have effects on many, many,
aspects of the environment of the ECU. Likewise, the reference and
perceptual signals can have sources in many, many, places outside the
ECU. For most, perhaps all ECUs, ALL of those sources are inside the
organism. Why I say "most, perhaps all" is because I do not know the
extent to which the peripheral muscles and sensors have the
characteristics of ECUs. They are the only places where there is
contact between any ECU and the world outside the organism.
Martin, lets focus on the ECU for a moment. I'm afraid I'm a bit confused.
In studying PCT all these years I felt the environment was _always_
considered _outside_ the body, and disturbances from the _external_
environment were part of the model.
I can see where your confusion comes from (I think). It's true that
most discussion talks about "a control system" without distinguishing
between the entire complex (of which the hierarchy is the
hypothesised implementation) or an ECU (which is the hypothesised
atomic unit of the complex). When "a control system" means an
organism that is influencing its perceptions (very plural, and at
many different levels of abstraction) through its "environmental
feedback path", then indeed the environmental feedback path is
entirely outside the organism.
However, when one is dealing with ANY control system, whether it is
an ECU, a complex network of ECUs, a level in the hypothetical
hierarchy, or anything else, what is in the environment is everything
affected by the output(s) of that control system and everything that
influences its input(s). So, if the boundary of the control system
under consideration is not the skin of the organism, then some of the
environment is inside the organism.
No one ever tried to disuade me or
anyone else from this notion.
Probably either because it was not clear that you (or others) might
not recognize the distinction between control system and organism, or
because in most experimental cases, what an experimenter can observe
lies usually outside the organism, so the control system in question
is asserted to have its "skin" coincident with the organism's skin.
In fact in B:CP, LCS I, and Mind Readings, any
number of diagrams are shown with the control unit inside the organism and
the environment outside, clearly delineated as such.
True, I suspect for the second reason above. But you must recognize
that any diagram of a hierarchy shows ECUs at levels above the
peripheral sensors and muscles. All such ECUs have an environmental
feedback path partly inside the organism. In fact, if you think about
it, the environment of any ECU includes everything outside of it, and
that usually includes the source of the reference signal as well as
the ECU's environmental feedback path.
Your notion of the ECU
and its environment makes perfect sense. A disturbance to an ECU is a
disturbance, it doesn't make a difference where the disturbance actually
comes from, its _external_ to the ECU. But I do not believe that this is the
picture that is given in the PCT literature. I say this because in showing
HPCT, in Mind Readings for example pg. 137 is a diagram of a three level
hierarchy. In it the ECU's pass through the 'environment' only at the first
level and are exposed to disturbances only at that point. They are _not_
exposed to 'internal' disturbances on the way down the hierarchy from level
to level.
True, again. But the idea there is simply to show that multi-level
hierarchies can work in the face of external disturbances. I don't
think it would be too hard for Rick to extend his spreadsheet model ,
as a proof of concept, to incorporate disturbances that enter into
the second or third level perceptions (not to be used as a model of
actual human processing). Rick??
I am _not_ advocating the need for disturbances here. I believe the effects
of attention and emotion can be handled in the input function. This of
course is subject to change I like the notion Martin presents on the
ECU's and toward that end I have a question or two. How _do_ we distinguish
between an organism and its external environment when using ECU's?
I think that's easy, once you define what sensory inputs are
available to the (possibly complex) control system, and what
effectors it has. Let's get physiological for a moment (a terrain
with which I am barely familiar :-). It is (reasonably) clear that an
entire human under normal conditions has input sensors for certain
electromagnetic waves, whereas other EM waves have effects that are
not sensed but do affect internal states of the organism (think gamma
ray damage to DNA, for example). Both varieties affect the behaviour
of the organism, but only the sensed ones do so through the immediate
action of the hypothetical hierarchy. The others do so by affecting
the hierarchy itself, either through direct damage (in the case of
Gamma radiation) or through reorganization caused by the departure of
intrinsic variables from their reference values.
Define the "skin" of your control system (complex) and you have
defined the external environment. It's everything not inside that
"skin".
I thought
a reference condition was endogenous to a PCT control system. That is the
reference condition is set by internal rather than external means. How do we
distinguish this with ECU's?
A reference condition is the input to some process that creates a
reference signal. That process has been much less studied or
discussed than has the perceptual input process. Nevertheless, in the
hypothetical hierarchy, there must be some process that allows the
outputs of many higher-level ECUs to combine into the scalar that is
the reference signal for one lower-level ECU.
What this means is that there is an easy confusion between the terms
"reference condition" and "reference signal." I don't think that
distinction has been articulated on CSGnet as far as I can remember,
but it should be. The "reference condition" is a good way to describe
the vector of signals that combine through a "reference input
process" to form a scalar "reference signal." Normally, when we talk
about the behaviour of an ECU, we are concerned only with the
reference signal, not the reference condition.
> If the "imagination loop" exists in some or all of the ECUs that
compose the hierarchy, then there must be a means of merging or
switching between the perceptual input from outside the ECU (but
within the organism) and the perceptual input through the imagination
loop. At high levels, when the signals to and from the world outside
the ECU are switched out, we call the process "planning"
Why the need for switching?
I said "merging or switching". The reason is that the perceptual
signal is a scalar. At best, the input from outside and the input
from imagination form a 2-vector.
If we understand how perceptions are constructed
(or can come close in theorizing about them _functionally_) I believe that
will provide us with some key insights into how memory functions. (at least
as far as the PCT model is concerned) I am much less concerned with the
actual mechanisms of how memory works than I am in how it functions and is
integrated into our ability to make perceptions, plan, etc.
No problems here. It's a worthy enterprise. But to deal with it in
terms that can be accommodated in a discussion of PCT, it's a good
idea to be clear about just what construct is under consideration.
There are lots of possible ways imagination and memory may enter the
model, and (Gods of PCT forgive me) everyday experience and much
clinical and experimental psychological evidence tells us that there
are several different kinds of memory (kinds, according to how they
manifest in experience and in behaviour). There's the "know how to
ride a bike" kind, the "I went to the beach last summer" kind, just
to name two.
> Thanks. I hope this message makes it yet clearer.
Yes, and raises some questions as well. Thank you
Good questions are always welcome.
> (2) Remember that outside an ECU is the rest of the organism, and
emotions and the like come from outside the ECU, just as do signals
from the world outside the organism (unless, of course, they are
generated in one of the ECU's processes, meaning that the ECU's job
is to create an emotion corresponding to a reference value for that
emotion).
Not to nit here Martin but 'signals' don't exist in the external
environment.
I didn't say they did. I referred to "signals from outside the
organism" which doesn't mean that the signals themselves exist
outside the organism. Remember Bill's attempt to define a signal?
It's an information-carrying device, and there's no information
without a receiver of that information. The signal is a signal only
when received.
Various energy stimuli do, and I think the distinction here is
important for a number of reasons. Our sensory organs (our 5 main senses)
transduce the _external_ energy stimuli into internal 'signals'. It is these
internal signals and not the external energy that is 'controlled' in our
bodies.
I don't think you'll hear a peep of disagreement from me, Bill P., or
Rick, about that. Or at least, I hope not
Second, emotions, I believe, are a side-effects of what ECU's
produce and do not 'come' from the outside. How about an ECU's job of
creating an emotion based on an error signal?
A whole nother domain of enquiry. It's well worth pursuing.
For what it is worth, I personally don't believe that emotion is a
general consequence of error in just any ECU. But then again, I could
easily be wrong. For all the evidence I have at hand, your guess is
as good as mine. But to talk about it, we need an agreed substrate of
understood material, and on CSGnet, that usually is an acceptance of
the idea of an ECU and of ECUs being organized into a hierachy. When
that basis is not accepted, the deviation has to be spelled out (as I
have done on one or two occasions in the past, and no doubt will
again in the future).
Martin