[From Bill Powers (2008.12.24.1524 MST)]
In PCT what motivates
behavior is error signals, differences between what is being perceived
and what a reference signal is specifying to be perceived. I don’t see
any ideas like that in this article.
It starts at page 555.
"An animal comes with a set of basic ‘drives’ that provide the
‘motor’
(motivation) for behavior.
According to PCT, this is incorrect. The cause of an animal’s behavior is
the same as the cause of a human being’s behavior: a difference between
what is being perceived and a magnitude or state that a reference signal
specifies as the desired or intended perception. There are no
“drives” and there is no such thing as “motivation.”
Those words go with a model of behavioral organization based on some bad
guesses, a model which PCT replaces entirely.
Most of the neural circuitry
underlying
these drives involves specific nuclei of the hypothalamus. Swanson
[24] introduced the notion of the ‘behavioral control column’
(Figure
1), comprising interconnected sets of nuclei in the hypothalamus
underlying specific survival behaviors: spontaneous locomotion,
exploration, ingestive, defensive and reproductive behaviors. The
hypothalamus sends this information to higher centers such as the
amygdala and the orbitofrontal cortex."
If PCT is correct, this paragraph is a remarkable collection of
confusions. The hypothalamus sends information to higher centers, yes:
but that is the set of perceptual signals (some of them) being controlled
by those higher centers, which compare the perceptions against
their reference signals and, on the basis of the error, adjust the
reference signals in the hypothalamus by a return path. This is the
somatic branch of the hierarchy to which I refer; I would guess that the
upgoing signals carry the “feeling” perceptions of which my
model speaks, though of course those can come from elsewhere, too. The
downgoing signals set reference signals for the patterns of physiological
states that are adjusted to fit with the actions governed by the
behavioral branch.
I’m aware of that error signals
motivate behaviors in PCT. In my
opinion, the stuff he was trying to refer to is more likely to be
the
reference, and Figure 2(a) looks like the diagram of a control
system
in PCT, if signals coming from the hypothalamus are reference of the
mentioned system. I don’t know much about structure of the brain;
the
hypothalamus seems to be just a third order structure instead of
some
ultimate level sending out the primitive reference, according to
B:CP.
I agree, I put it at the third order of control, too: the controlled
variables are configurations of somatic – biochemical –
sensations.
For reference, I’m
attaching another version of my ideas on emotion. I keep
trying to find clearer ways of describing it. This doesn’t sound
much like
what Arbib et. al. are saying.
The ideas are wonderful! From my perspective, interactions in the
hierarchy of control system might caused the emotion, a side-effect
as
you recognize it, to be perceived as a stimuli in the S-R
system.
What SR system? There are no SR systems in organisms. You have to get
used to that idea if you’re going to use PCT. Individual components of
control systems convert input signals to output signals, but these
components make up a set of control systems which are not SR systems.
They are not SR systems because they control, and they are not SR systems
because we do not conceive of inputs and outputs of components as
consisting of brief events (except at one proposed level, the fifth). In
lower-order systems, from intensities to relationships, neural signals
are continuously variable, not discrete, and at all levels there are
indications of an underlying continuum even when discrete variables are
used. I have mentioned that I think the “event” level is out of
place, but I don’t know where to put it.
For example, behaviors of
control system A bring up some changes, not only
in the controlled perceptions of system A but also in other parts
of
the whole system, and perceptions of these “other parts”
are
controlled by another system B, whose reference value is static at
that time. In this process, the signals go down a branch of system
A,
and go up through another path in the system B, then go down again.
People losing sight of the whole process could easily link the
emotion, brought up in the first “valley” of the go up and
down
process, with the behaviors produced in system B.
Yes, but wait until you see some of the demonstrations in the new book,
which show multiple control systems sharing a common environment which
they all sense and affect, yet continue to control independent aspects of
that environment. The phenomenon you describe is just the tip of the
iceberg.
Besides, it is exciting to see
the idea “Awareness is mobile”. I
recognize the awareness as a “rolling ice ball floating in the
water”;
the part beneath the water surface is what we are unaware of. It’s
nothing like Freud’s iceberg metaphor as his “iceberg” never
roll. If
there is something hard to be awared of, it is not included in this
ball. I am not quite sure about what kind of “forces” make the
ball
roll; it could be something like attention.
Great minds think in the same channels, right? I can add to your rolling
iceberg a balloon overhead. Awareness tends to dwell in the middle levels
of the hierarchy, and not so much in the lower or upper levels. If
I asked you to tell me right now what goals are behind the fact that
you’re reading this post at this instant, the first thing you’d have to
do would be to stop reading. Then you would have to look inward, and
goals would come to your awareness, and you would tell me. But you
couldn’t tell me the answer until you had moved your awareness away from
the main thing you were consciously doing. The higher goals and control
systems were obviously operational all the time, but you weren’t
conscious of them.
ps:
Here is another interesting example about the controller in robots.
In
a summary of evolutionary robotics:
http://www.mae.cornell.edu/ccsl/papers/Biomimetics05_Lipson.pdf
Professor Lipson described an experiment in the section
"Evolving
Controllers" on page 4. In Figure 1(b), there are two
“mysterious”
nodes B1 and B2 without any explanation in the related text, which
is
filled up with the words like “mapping inputs to outputs”. In
the
reference "Evolved Sensor Fusion and Dissociation in an
Embodied
Agent" about the original work
http://www.cs.uvm.edu/~jbongard/papers/BongardWGW02.pdf
there is a single sentence mentioning these two:
"There is an additional bias neuron at the input and hidden
layers
that outputs a constant signal of 1."
In this experiment, 200 candidate controllers were evolved for 50
generations, and the Quadrapod succeeded in moving towards high
concentration of simulated chemicals at last. I don’t know how
output
weights of B1 and B2 evolve in the simulation, but I guess their
outputs are recognized as reference signals and negative feedback
emerged.
I’ll read those papers later. It’s interesting that in all of these
“genetic algorithm” models that I have seen, the designers have
to let the evolving organism reproduce even though it hasn’t yet learned
how to do what is necessary to survive. In your last quote above, we see
that 50 generations had to pass before the Quadropod “succeeded in
moving towards high concentration of simulated chemicals at last.”
If it didn’t actually reach the chemicals, how did it survive through 49
generations? It survived because the kindly programmer saw it was
changing in the right direction, and allowed it to survive. There is no
kindly programmer helping real organisms that way.
In PCT we use a different basic principle, that of reorganization.
Reorganization depends on sensing some critical variable and detecting
whether it is changing toward or away from some specific reference level.
Changes in system’s properties – the coefficients in the equations that
define it – are always going on at different rates; those different
rates are like E. coli swimming in a straight line in some hyperspace of
coefficients. If the error signal is decreasing, those changes continue.
If the error signal ever increases, however, this reorganizing system
“tumbles” by altering the rates of change of all the
coefficients, at random. The random tumbles continue until the error is
once again decreasing. The system now swims in a new direction through
the coefficient hyperspace. To make the system converge to a final result
properly, the speed of swimming is determined by the total squared error
in all the critical variables. As the error decreases, the changes become
slower. They may stop at some minimum but nonzero error level.
You knew all that, but I thought I’d just say it again. You can see that
the genetic algorithm programmers have had to do this too – they are
serving as the comparators in the reorganizing system, because they can
see when the changes are leading toward the goal or away from it. Their
system tries to work by “rewarding” behavior that leads toward
a favorable result, which is the idea behind reinforcement theory
(though Skinner’s version demands that the favorable result actually
occurs). In reorganization theory, the organization of behavior is
altered only when the result of behavior is actually
unfavorable.
In all theories of learning, it turns out that something has to detect
whether the changes have more-favorable or more-unfavorable results. If
that’s not done, survival becomes far too unlikely. The difficulties
arise when we ask how an organism, or the environment, can know that a
change took the organism closer to a favorable result, when that result
didn’t actually occur. Reorganization theory offers a solution for that
problem that doesn’t involve a helpful programmer.
Best,
Bill P.
P.S. Please tell us which is your family name and which is your personal
name. It’s very confusing because Chinese writers, being friendly and
polite people, sometimes switch the two names around and put the personal
name first so we Westerners (who live to the east of you) will know which
is the “first name”. But of course, some Chinese writers
don’t do that, so we never know whether to switch the names back
or not.
In the English-speaking American navy, I would write my name on forms or
speak it to superior officers as “Powers, William, 7275198.”
The comma, or a little drop in tone and a pause when speaking, indicate
that the last name is being given first (to please clerks who like to
list people alphabetically by their family names). So ALL YOU GUYS OVER
THERE, how about simply writing your names the way you like to see them,
and putting a comma after the family name, as in
“Wang, Bo” – or is it “Bo, Wang”? If you want to
write it our way, just leave out the comma. You can send the Nobel Peace
Prize to my current address.
···
At 08:14 PM 12/24/2008 +0800, Wang Bo wrote: