[Hans Blom, 951101]
Bill Powers (951031.1050) replying to Bruce Abbott (951030.1715)
A nice essay on Thorndyke and his cats. Let me try my own
interpretation using the biases of PCT.
Your reply makes the distinctions very clear. And also that you pit
one theory against another. Some remarks:
To the observer, the cat's actions are the "doing," but to the cat,
the consequences of those actions are what is being done.
How do you know? Unfortunately you are locked into the position of an
observer and cannot be the cat. You're only guessing (i.e. theoriz-
ing). Since YOU BELIEVE THAT the consequences of actions are what is
being done, you attribute the same point of view to the cat. Are you
doing more than Thorndyke, i.e. formulating a hypothesis which needs
further corroboration?
Since the cat was probably not controlling for brushing against the
pole (unless it was intentionally marking it as cats are wont to
do), this side-effect of its control actions was not connected to
any subsequent event. From the cat's point of view, the door simply
fell open by itself while the cat was engaged in controlling other
things.
Do you really think so? In my view, the cat was trying to solve a
problem; to gain control, one might say, over its situation. Then
suddenly, unexplainedly, the solution was there and, moreover, was
immediately recognized as such. A far more important event, I think,
than "the door simply fell open by itself". So important, maybe, that
some internal mechanisms made something of a "snapshot" of the situ-
ation, not only of the door falling open but of everything else that
happend at/around that moment too. Now I am theorizing ;-).
But after this had happened a number of times, and after the cat had
tested each of the controlled variables for an instrumental effect
on opening the door, one controlled variable proved to have a
connection ...
An alternative explanation: Superimpose a number of those "snapshots"
that were taken when solutions occurred, kind of like averaging, and
a pattern might present itself: a more or less reliable and signifi-
cant connection between the door opening and some action. No certain-
ty yet, but at least a possible way to a solution that ought to be
given a higher priority over other ways.
The relative frequency of the different behaviors is probably not
pertinent to the cat's actions ...
Maybe it is. Goals, except the topmost ones of the hierarchy, are
means, methods, tools, that can be employed to reach the topmost
goals. Try out the methods that appear most promising first, and
relative frequency becomes an important notion.
... the ordering of the frequencies and the connection with
probabilities happened in Thorndyke's brain, not the cat's.
In probabilistic model-building, degrees of certainty (or relative
frequencies) are an important notion. They don't only exist object-
ively -- where an observer can watch them -- but also internally in
the model itself. So your remark
All the probabilities and orderings into a hierarchy are part of
Thorndyke's behavior, not the cat's behavior.
is not correct from the point of view of model building.
This assumption shows Thorndyke's theoretical slant; he begins by
assuming that there must be something about the situation that is
causing the behaviors he sees: the basic S-R assumption.
Is this not natural? In order to perform The Test, you first need an
assumption, a theory/theorem. Or preferably more of them, so that, in
a process of differential diagnosis you can eliminate what doesn't
work and keep what does. But the people -- unless rigorously trained
-- have this weakness to grab the first explanation that seems to
work and not try out different ones. Just like one of Thorndyke's
cats might think it has discovered that rubbing the pole opens the
cage door, whereas in reality it is rubbing the pole FROM A CERTAIN
DIRECTION that does the trick. If the cat did not try all directions
but in each case happened to be in a position that worked, it would
not have discovered the "true" solution, but only one that "worked".
If Thorndyke had simply asked how he would figure out how to escape
from the box if he were the cat (and knew only what the cat probably
knows), he would have realized that the relative frequencies of the
behaviors have little to do with the matter: the real problem is to
figure out what to control in order to control something else.
But in solving this "real problem" whose solution in terms of specif-
ic actions is as yet unknown, (un)certainties or relative frequencies
might play a major role, if only in ordering the possible means of
solving the problem in terms of what seems most promising. Note that
this is different from the standard PCT approach, in which _one_ non-
discrete action (u) must be quantified. Now the problem is _which_ of
a (discrete) number of actions (mechanisms) is to be employed, and
how to perform this selection.
All that matters is eliminating those behaviors that are not having
the desired effect on another variable.
This assumes that one can reach _certainty_ that a certain type of
behavior does not contribute towards the solution. Initially, this
will be unknown. Is it just rubbing against the pole that works? Or
rubbing in a certain position? Or must something else have been done
before? It is not difficult to think of problems that cannot easily
be solved, except through helping the animal to discover a solution
(shaping).
Of course in putting oneself into the cat's position (as I did
above), one gives the cat too much credit for reasoning, but once
the basic problem facing the cat has been seen, one can try to
imagine more cat-like processes by which the same result could be
achieved.
The problem is simpler, in my opinion. You have a problem that needs
to be solved, so you try all approaches to a solution that you can
"think" of and that you have in your repertoire, either innate or
learned. That seems simple. What is not so simple is the order in
which to try out all those possible solutions. Here you need some
(assumed) knowledge about which approaches are most promising. This
is where mechanisms that can handle uncertainty are needed.
And don't forget one other thing, which is extremely important.
Initially the cat has no idea that the solution from case to case
will be the same: rubbing the pole. This is something that has to be
discovered as well. If this were known initially, a "reasoned" or
systematic approach might work well If not, then not, and probably
trial and error (guided by impressions about what might be tried out
first) are all that remains.
Greetings,
Hans