[From Bill Powers (950104.0600 MST)]
Martin Taylor (950103.1130) --
The localized reorganizing system is different from the separate
reorganizing system, yes. It is an attempted answer to the
question "Is it absolutely necessary at this stage of understanding
PCT to assume that there exists a separate system devoted to
reorganization." It is necessarily different from the separate
reorganizing system in that it suggests that the answer to the
question might be "No, it is not absolutely necessary to assert
that reorganizing is done by a system separate from the main
in B:CP, p. 182:
"This _reorganizing system_ may some day prove to be no more than a
convenient fiction; its functions and properties may some day prove to
be aspects of the same systems that become organized. That possibility
does not reduce the value of isolating these special functions and
thinking about them as if they depended on the operation of some
So my answer to your question was given 21 years ago: no, it is not
necessary, but it is a conceptual convenience to see the properties of
"the" reorganizing system as being different from those of the hierarchy
of control systems "it" brings into being.
I proposed that the outputs of the control systems for the
intrinsic variables contribute to reference signals in the main
hierarchy, rather than causing changes in the structure of the main
hierarchy. This seems to me to be reducing the number of ad-hoc
processes, not increasing them.
I had commented:
If the higher system affects the lower only by varying the value of
its reference signal (first paragraph), how does it also vary its
linkages and functions and cause new ECU's to grow (second paragraph)?
You need to give each ECU capacities for doing those operations as
well as varying the values of reference signals for lower systems,
and your reply was:
I don't suppose it is worthwhile restating it yet again. But, YES.
Each ECU in the localized reorganizing scheme is allotted the
capacities that are allocated to the separate reorganizing system
in that scheme, but they apply only to its OWN local environment.
You seem to forget your own words within one page of having uttered
them. You want to "simplify" the process of reorganization by
eliminating the capacity to alter the hierarchy structurally, but you
then claim that your model "... is allotted the same capacities that are
allocated to the separate reorganizing system...".
By eliminating structure change as a consequence of reorganization, you
eliminate the fundamental property that I gave it in order to account
for the development of the hierarchy. By making reorganization work only
through adjustments of reference signals, you assume that there are
already places to send reference signals, so the hierarchy must already
be in existence in order for reorganization to work. This assumption, of
course, is what requires you to think of the initial reorganizing
process as equivalent to a highest level of control in the hierarchy
which works initially by sending reference signals directly to the motor
output systems. And having made that assumption, you must then propose
that new ECUs are "inserted" between the highest level and the lowest
(this somehow happening only through sending reference signals to lower
systems which do not yet exist, and without structural changes).
By proposing that reorganization works only through adjustments of
reference signals, you add to the reorganizing process an effect that I
did not put in it. In my proposal, changes in reference signals come
about through structural changes in the systems that are generating the
reference signals. It would make no sense for reorganization to set
reference signals directly, because in general there is no one "right"
reference signal. All reference signals must be adjusted by higher
systems on the basis of current disturbances and higher reference
signals, not be set to particular values. In my system, reorganization
does not produce any particular reference signals; it alters the
_relationship_ between the reference signal in one system and the error
signals in higher systems. That is a structural change, not a change in
In short, I proposed a reorganizing system that works _strictly_ through
making structural changes, not through manipulating signals in the
hierarchy. You have proposed one that works exclusively through
manipulating signals in the hierarchy, not through making structural
Anyway, all this sounds quite incompatible with the Genetic Algorithm
approach, in which new ECUs are developed not by experience with the
current environment or failure to control in that environment, but by
combining ECUs from the parents.
What kind of dormitive principle is this you are espousing? New
ECUs developed "by experience with the current environment or
failure to control in that environment"? How, pray?
When the current environment is such as to cause intrinsic errors, or
renders existing control system ineffective so they contain large and
persistent error signals, reorganization starts, altering the
organization of existing control systems and, especially during
development, creating new control systems out of "uncommitted neurons."
The Genetic Algorithm, however, creates new control systems only by
combining the properties of control systems that existed in the parents.
This proposal attributes an entirely different origin to the control
systems in the offspring. It says that the newborn child contains
control systems in a hierarchy that resembles the hierarchy in the
parents, except that the properties of each new control system are some
combination of the properties of the parent's equivalent control
systems. Under the Genetic Algorithm approach, there is no need for a
reorganizing system except perhaps to tune the properties of the
inherited hierarchy of control. The inherited hierarchy contains all the
levels and connections that are in the adult parents, from the very
beginning, complete with the organization of perceptual functions and
output functions as well as the interconnections from level to level.
This is necessary because a single ECU has no meaning in isolation; it
perceives only though lower perceptual processes, and it acts only
through lower control systems, so its properties must be appropriate to
the properties of all the systems below it. If one ECU is inherited,
then necessarily all ECUs below it that are related to it must also be
In my proposal, all that is inherited in a human being is a set of
levels of brain function, each one containing the basic materials from
which control systems of a particular type can be constructed, but with
no other pre-organization, or very little. The capacity to adapt
behavior for controlling a given environment is inversely related to the
amount of inherited organization in a system. I have chosen as a
starting point the assumption that _all_ structural organization in the
human brain arises through reorganization and that _none_ is inherited.
I will no doubt have to relax that rather extreme assumption some day,
but the more we can account for without relying on help from genetics,
the less burden we place on genetics to account for the events of a
I hope I have made my position clearer.
Take as the watchword in understanding it: Everything about the
reorganizing system is the same in the two proposals, EXCEPT its
distribution or localization.
Then whether it is distributed or localized, the reorganizing system
operates strictly through making structural changes in the brain, and
not through manipulation of the same signals that flow in the hierarchy
of behavioral control systems. The variables it controls are not the
variables that the hierarchy controls, but intrinsic variables at a
level of which the hierarchy knows nothing. If this is what you mean,
then I can accept the above "watchword." Somehow, I doubt that this is
what you mean.
As to the three types of perceptual function you have been mulling over,
I don't think you have considered how they would work as input functions
in a control system.
For the curious, the three different kinds of perceptual function I
have mulled over are: (1) functions that combine incoming values
with some kind of weighting function, possibly with mutual
multiplication, and apply a non-linear saturating function to the
You seem to be forgetting that a control system controls its perceptual
signal, not the inputs to the perceptual function. If the perceptual
signal is being made to track a changing reference signal, then the
inputs to the perceptual function must vary as the inverse perceptual
function of the reference signal (or one of the inverses). A saturating
input function would thus require the inputs to become extremely large
when the reference signal demands a perceptual signal near (or above!)
the saturation point.
All you're doing here is adopting (loosely) the architecture that others
have proposed for adaptive neural nets. This architecture is designed to
produce categorical outputs on the basis of varying inputs; it is not
designed to create a perceptual signal whose variations are proportional
to variations in some external physical variable. This kind of input
function could not be used to model tracking behavior; its presence in a
control system would lead to behavior that we do not observe.
Your other two types of input functions are even worse-adapted to the
requirements of control, as you would find out if you tried to build a
simulation based on them.
Don't forget that in the original attempts to get a Little Baby going,
your team was unable to make even a single control system operate using
the proposed integrating sigmoid input function until I persuaded them
to try a simple linear input function. That was at least two years ago.
What makes you think the nonlinear saturating input function is going to
work any better now?
A general comment based not only on the above interchanges but on papers
I've been receiving from various people:
When an attempt is made to bring together the latest or most influential
thinking to produce a model of behavior, the result -- even not
considering PCT -- impresses me as a mess, not an advance. The problem
is that reinforcement theory, Freudian theory, information theory, goal-
setting theory, genetic theory, quantum theory, neural network theory,
fractal theory, dynamic systems theory, classical conditioning theory,
Gibsonian theory, and all those other theories were never designed to
work together. Each one was developed from specific assumptions (both
covert and overt) and from observations that the others did not take
into account. A composite of all these theories is not an improvement on
any one of them. It is just a confusion of random ideas pulling in
When you try to mix PCT with all these other theories, the confusion
just becomes worse. If you stir a Big Mac, fries, and milkshake into a
big bowl with breakfast, tea, and dinner, the result is not an
improvement in the Big Mac lunch but garbage. Even the Big Mac becomes
just more garbage. That is what happens when PCT is combined with all
these older theories: it turns into garbage. It may not have been the
ultimate gourmet repast to begin with, but it is not improved by trying
to combine it with a mishmash of other ideas thrown together at random.
PCT covers a lot of ground and it was constructed to hang together
without internal contradictions. It is based on a fundamental phenomenon
that none of the other theories it keeps getting mixed in with took into
account, and in many cases it offers alternative explanations of
behavior that contradict the explanations offered by other theories. For
essentially every other theoretical explanation, PCT leads to a
_different_ and usually _incompatible_ explanation. You can't just start
plugging other theories into PCT, or vice versa, and expect to get some
magical synergistic (oh, yeah, synergism theory) whole that is greater
than its parts.
I think it may be have been Dag Forssell who came up with an analogy:
building a car by using the best features of all the automobile
manufacturers. Combine the wheels of a Mercedes, the carburetor of a
Maserati, the engine of a Rolls Royce, the suspension of a Volkswagen,
the body of a Chevrolet truck, and the electronics of an Infiniti, and
what do you get? A nonfunctional monstrosity.
Best to all,