[Martin Taylor 2018.11.15.17.54]
A postscript to
[Martin Taylor 2018.01.15.12.30]
I mentioned that conscious perception involved qualia, but I should
also have mentioned that conscious perception and control of a
program is sometimes called a “plan”. In planning, one consciously
does perceive an imagined program or at least parts of one. Might we
speculate that this is an aspect of what working memory is for?
After I started writing this, another message arrived from Bruce
Nevin, to which I will respond here.
This is true of EVERY upward shift of level. That the additional
structure includes time makes them no different. The reason we have
levels of different kinds of perception is that each new level
introduces something not part of the existing levels.
Yes. And your point is?
As I understand it, the sequence perception will not be in error
while the “A” loop is operating, provided neither the “B” control
loop nor the “C” loop has just been active or is currently active.
The perceptions available to the sequence controller need not be of
the actions involved but are likely to be of the changing state of
the perceived environment, in which B should not be influenced
before A is near its reference value.
If you are asking about how a sequence perceptual function might
look in a simulation, I can’t answer with the kind of precision that
would allow you to build a model, but I can suggest some possible
components, the most obvious of which is a shift register (as Bill
P. described in the Figures from B:CP Chapter 11 that you cite). The
shift register provides reference values to lower levels that change
as the stage of the register moves from A to B to C, starting with
A. There must exist methods in the brain that allow for one control
loop to be active while another potentially conflicting one is
inactive, nd those same mechanisms are presumably invoked in the
operation of the sequence controller.
A question about controlling a sequence is "Why wait to control
B-ness" until after “A-ness” has done its work?“. If you want “B”
and you can control “B-ness” without doing “A” first, why invoke an
“A-ness” controller at all? One answer is that sequence controllers
are used to create a useable environmental feedback path for a
“B-ness” controller by first using an 'A-ness” controller. Another
is that “A-B-C” is part of a ritual in which the possibility of
“B”-ing independently does not contribute to a perception matching
the reference “A then B then C”, though I think this to me looks
more like the specialized kind of sequence called an “event” such as
the construction of a spoken or written word.
When the "A-ness" controller has completed its work so that the
“B-ness” controller has an effective environmental feedback path,
that may be adequate to trigger the shift register (if the
alternative circuit I described a few months ago works, that trigger
would be low error in the A perceiver). After being triggered, the
shift register would switch the active perceptual function so that
it produces as its output a value of B-ness, because that would mean
the sequence was proceeding as its reference value demanded, and so
on through the sequence, however long it might be. The inputs from
the sensors to the component lower-level perceptions determines
whether they are being properly performed.
As a parenthetical note, this "need for A to allow B to be
controlled" does not require a sequence controller as such, but even
without invoking a sequence controller it does create observable
actions that reliably mimic the actions that would be produced by a
sequence controller. Control of B reliably follows control of A in
either case.
The key point is that if a high reference value for the sequence
perception does not match the present value of the sequence
perception, the sequence is not yet being performed accurately, just
as is the case for any perception, and action is needed to bring the
sequence perception nearer its reference value. If control of B
doesn’t start soon after the state of A creates a trigger, then
something is wrong with the sequence control and it needs to be
fixed, just as is the case if any other perception is not properly
influenced by the output action.
There may well be a problem in creating a sequence perceptual
function that works; the same is true for just about every
perception in a natural world. That’s why it has taken the best part
of half a century to produce effective automatic speech recognition
or handwriting recognition functions. We know it can be done, but we
don’t know how it is done, which is probably very different from the
way artificial systems do it. Even when the problem is solved with
something like a deep neural net, we don’t know what the net does
that makes it succeed.
No. The action loops are lower level loops, not intrinsic to the
sequence perception. They are the content of what is sequenced. The
sequence itself is more abstract, consisting really of a pattern of
“That’s done, so let’s move on to the next thing” where the “that”
and “next thing” may not be built-in to any particular sequence
perception but may be linked in as needed by means not incorporated
in the pure hierarchy.
[Incidentally, I missed a necessary element of a control loop, but
since it is not a part, I forgive myself. That missing element is
the asymmetry between the low sensitivity of the environment to the
processing done in the perceptual function as compared to the high
sensitivity of the environment to that done in the output function.]
Yes. That's Bill's quasi-neural implementation of the shift register
I was talking about, The loops in the figures are simply what Bill
calls “recirculation” neural loops that sustain a value until a
trigger moves the sequence perceiver on to the next stage.
Yes, that's how I see it, except that I see the sequence perceptions
not as part of the program perception but as lower-level perceptions
performed at the right time in the same way as the “A-B-C” controls
are not part of the sequence controller that invokes them in turn.
I’m not sure from what you write how you see them, because it could
be interpreted as taking the sequence after a choice point to be
part of the program perception of which the choice point is part.
I would suspect that conception fails to match reality, on the
grounds of inefficient use of neural resources. But as I said
previously, we are in an area where data is sparse or non-existent,
so disagreements are likely to be based on misinterpretations or on
duelling intuitions. Neither possibility provides a good reason to
sustain a conflict.
Yes. In that case, the sequence would not be at all abstract, and
would have the content “baked in”. Maybe everything we ascribe to
“sequence control” is actually “event control” or the actions of
individual controllers such as the B-ness controller that cannot
effectively influence its perception without using an A-ness
controller, as, for example to see the room contents requires light
and to perceive that there is light requires turning a switch or
acquiring a flashlight.
That sounds right, too.
Martin
···
[From Bruce Nevin (2018.01.15.17:40 ET)]
MMT: I would not say that the program control system
is structured any differently from any other control
system. To bring it down several levels, imagine a
configuration control system, and to make it concrete
let’s say that the reference configuration is a simple
wooden chair, and you have on hand four legs, a seat,
and a back pre-built. What do you control and do? From
outside, it looks as though you take the seat and attach
to it the five other elements one after the other.
Yes, the input perceptions that constitute a
configuration are (or may be assumed to be) simultaneous.
They do not have to be perceived or controlled at
different times in order to perceive the configuration.
But no, programs, sequences, and events have some
additional structure.
Unlike e.g. a configuration, the input perceptions
that make up a sequence or a program are separated
temporally. In the sequence A, then B, then C, control of
A is a precondition for controlling B, and control of B is
a precondition for controlling C. Insert key in lock, then
turn key, then pull on the handle of the cabinet door. In
the program if A, then B, else C, A must be controlled
for first as a precondition for either controlling B or
controlling C, depending upon the result of controlling
for A.
MMT: The parts are
MMT: 1. A perceptual function that produces a scalar
value called the perception. This is the value that the
loop controls. The number of stages of processing
between sensors and the inputs to the perceptual
function define the level of the control loop in the
hierarchy.
MMT: 2. A comparator, which exists only when the
control loop is to be able to vary the value at which
the perception is controlled – in other words a
comparator exists in a control loop at all levels of the
hierarchy except the top.
MMT: 3. An output function that provides a scalar
value as its output.
MMT: 4. An environmental feedback path through which
the scalar action output influences the inputs to the
perceptual function. This feedback path includes all the
processing that occurs between the scalar output and the
organism’s effectors as well as what happens between the
effectors and the sensors and between the sensors and
the perceptual function inputs.
MMT: 5. Two external inputs (one if there is no
comparator): a variable reference value input at the
comparator and a variable disturbance that affects
variables on the environmental feedback path.
MMT: That's it. In my view, every control loop
consists only of this, with the caveat that inputs to
the perceptual function may come eventually from
imagination as well as from sensors.
Nice summary. In a sequence, there is more than one
such loop, each of which has all five of those parts.
Each comparator receives a reference signal if and when
the prior one is perceived. I refer you to B:CP Figures
11.1 - 11.3 for one proposal of a neural mechanism.
A program consists of such sequences linked by choice
points at which only one of a set of sequences branching
from there receives a reference signal for the initial
perception that it requires, depending on whether the
perception specified at the choice point was perceived or
not.
This is also true of an event perception, as Bill
proposed it. In his view, a word is an event – a brief,
well-practiced sequence perceived and controlled as a
unit.
The structure proposed in Chapter 11 of B:CP
illustrates control of a word event, and could serve for
both events and sequences, the chief difference being in
the ease of controlling each of the series of perceptions
and of shifting one’s physical means of control from one
to the next.
