[From Bill Powers (950626.0630 MDT)]
Bill Leach (950625.13:07 U.S. Eastern Time Zone) --
You bring up a number of interesting points about reinforcement theory
and PCT. One recurrent theme is that the environment does have some
controlling effects on our behavior -- but then again, it doesn't!
Within limits, it is not unreasonable to conclude that the
"environment makes us "behave" the way that we do behave."
That some environmental factors have a consistant, testable cause
effect relationship to living beings is beyond dispute (at least
with anyone even pretending a scientific approach). For example,
placing a human (or any mammal) in a normal atmosphere except that
it is oxygen free for a sufficient length of time will result in
the organism's death.
But in another post:
If my goal is to drink a glass of milk, there are quite literally
thousands of different ways in which that goal might be satisfied
including the many different actions that would occur should there
not be any milk in the house or what exists is spoiled, etc.
One of the main points of the PCT model is to explain how it is that
there are quite literally thousands of different ways in which a given
goal might be satisfied, yet somehow an organism finds just the way that
will do the trick -- most of the time. This goes clear back to the basic
puzzle about behavior that William James noticed: variable behavior
producing consistent ends.
Probably the greatest hole in reinforcement theory was patched by the
most casual plastering job. Skinner noticed way back in the beginning
that what we casually describe as "the same behavior as before" is most
often a very different behavior from the one we saw before. The actions
of organisms, in the sense of the outputs they produce with muscles and
limbs, do not actually repeat from one instance of behavior to another.
What repeats is some particular consequence of acting. Rather than
asking how this can possible be, Skinner simply defined "the operant" as
any class of actions that has a particular effect.
At that point a serious question for a materialist explanation of
behavior arises: how is it that the same effect can be produced by
different actions? If Skinner had been inclined to take a physical-
science approach to behavior, this would have been a serious question
indeed. And a physical-science answer would have been of little comfort
to a behaviorist. The only way in which a consistent result can come
from variable actions is for the environment to vary in just the way
needed to make up for the variations in the actions.
That, of course, is putting it the wrong way around. The right way
starts by asking what the same consequence would have looked like
without the organism's actions. Where would the milk that you drank have
been if you had not acted? It might have been in a thermos jug, in a
carton in the refrigerator, in a grocery bag waiting to be unpacked, in
a store, or in a cow. Yet no matter where it is, you end up getting a
drink of milk. The only POSSIBLE explanation is that under each
different environmental circumstance, you produced just the physical
action required for the milk to end up in a glass and the glass to be
emptied down your gullet. Your action does not produce the final effect.
All it does is make up the difference between a particular final effect
and the effect that would have happened without the action. If someone
goes and gets the milk and puts it into a glass and tips the glass into
your mouth, the only action required from you to get a drink of milk is
to open your mouth and swallow.
The subject matter of PCT lies in the very part of behavior that Skinner
dismissed as basically unexplainable. When he said that behavior is
"emitted," he ceased to talk about the physical actions of the organism
and began talking about _physical consequences_ of those actions. What
is "emitted" is a change in the physical observable world due to a
change in the organism's action coupled with any change in the physical
world capable of altering that same physical variable. What we commonly
call behavior is really a resultant; the outcome of combining forces
created by an organism with forces that originate elsewhere.
When we see it this way, we realize how strange it is that an organism
can actually appear to emit the same physical consequence of action over
and over. We can't just say, as Skinner did, "Oh, well, the organism
just did one of the many things that could have had the same physical
effect." It's not as simple as that. In any one physical situation,
there is only ONE action the organism can take that will have a
particular physical effect. If the local environment changes in any way,
there is still only ONE action the organism can take to create the same
effect as before, but now it is a DIFFERENT action.
What's really going on is that when the organism emits a particular
physical effect, its action is PRECISELY THE ONLY ACTION THAT COULD HAVE
PRODUCED THAT EFFECT AT THAT TIME. Given the same state of the
environment, any other action would have resulted in a DIFFERENT effect.
As Skinner noted, there are many actions that can have the same effect.
But what he failed to notice is that this is true only over a large
number of instances of the actions. In any one instance, it is not true
that any number of actions can have the same effect. Given the current
effects of the environment on a particular variable, for that variable
to be in or remain in a particular state requires ONE AND ONLY ONE
ACTION by the organism. It is that action which, when added to all other
influences acting at the same time, will produce that particular effect.
When this fact finally sinks in, the problem of explaining purposive
behavior returns with full force. We can no longer just wave vaguely at
the details and say that one of the actions that could have had the
observed effect must have occurred. We must account for the fact that
the observed effect is produced and produced again, each time by THE
ONLY ACTION THAT COULD HAVE PRODUCED IT AT THAT TIME.
If you think of the process of getting from one state of the environment
to another, there are of course many trajectories by which this can
happen even in a single instance of behavior. To understand the import
of the point I'm trying to make you have to see the world at each
instant, not over a series of instants. At any point during any action,
the state of any variable including all its time derivatives is
determined by the sum of all influences on it. If the trajectory is to
repeat, then the action of the organism must at all times be exactly
what is required to make up the difference between the trajectory that
would have occurred without the influence of the action and the
trajectory that is to be reproduced. And at every instant, there is only
ONE action that can do this.
The basic problem in explaining behavior, therefore, is to explain how
it is that the one action that is necessary to produce a given result is
the one that is produced by the organism -- even when each instance of
"the same behavior" requires that a specific different action be
produced. This is the very question that Skinner's definition of "the
operant" bypassed.
···
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The other question raised by your comments concerns the role of the
natural environment in behavior. Does the enviroment "make" organisms do
anything? I claim it does not. But if it doesn't, what _is_ the part
played by the environment in behavior?
One thing the environment does is to determine the physical effects of
any action generated by the organism. The organism has, generally
speaking, no way of altering the physical laws that determine these
effects. If you exert a force on a free mass, it will accelerate; the
only way you can keep it from accelerating is to remove the force or add
a second cancelling force. There is no way any organism can learn to
apply a net force to a free mass without accelerating it.
A second thing the environment does is to have physiological and
physical effects on the bodies of organisms. A human organism will die
without oxygen, food, water, the right temperature range, and protection
against physical damage, to mention a few items. There is nothing an
organism can learn that will free it from such effects.
And a third thing the environment does is to stimulate sensory nerve
endings. When we speak about the environment causing behavior, the
causal path we usually mean involves the sensory systems. The question
really is, can the environment make the organism produce certain actions
by stimulating its sensory endings in the right way?
Let's not confuse this causal path with others. It's true that if the
environment is suddenly depleted of oxygen, a person would "respond" by
dying. So a requirement of continued life is a continued supply of
oxygen. But this fact does not make the organism seek oxygen. If the
organism did nothing to counteract the lack of oxygen, it would simply
die. The question is not whether it is necessary for life that the
environment be in a certain state; it is whether deviations from that
state can, in themselves, make an organism do anything in particular.
The answer is, of course, no. The only possible way in which lack of
oxygen could stimulate an organism to seek oxygen would be for the
organism to possess sensory equipment that could report on the state of
the oxygen supply, and internal organization that would convert a bad
report into an action that would have the effect of restoring the oxygen
supply. Whether such an action would occur does not depend on anything
in the environment. It depends on processes inside the organism. If
those processes are missing, the organism will die. If a lack of oxygen
could make an organism behave to restore the oxygen supply, then
organisms would never die from lack of oxygen. The environment would
make them do what is necessary.
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A search for "bigger" reinforcers or for the CCEV could look very
much alike.
Suppose we say that food is a reinforcer: more food, more behavior that
produces food.
If we are looking at food as a CCEV, then we see it a little
differently. We say, the more food there is, the less behavior there is
to produce food. When the amount of food reaches a certain level, the
behavior that produces it disappears altogether.
Are you sure you want to say that searching for reinforcers looks very
much like searching for CCEV's?
It seems to me that this, not the points you cite, is the basic
irreconcileable difference between EAB and PCT. We are talking about a
FACTUAL difference. When the amount of reinforcement increases, does
behavior increase (EAB) or decrease (PCT)?
In recent posts, I have suggested, and Bruce Abbott has tentatively
agreed, that the apparent increase in behavior due to an increase in
reinforcement that is seen under some schedules of reinforcent is
actually due to the organism's turning to other kinds of behavior when
the reinforcement rate is low, and spending more time on a particular
behavior when the reinforcement rate associated with that behavior is
higher than for other behaviors. The implication is that if the organism
continued to be engaged in a particular reinforcment-producing behavior,
the relationship would be that an increase in reinforcement goes with a
decrease in behavior and vice versa -- the opposite of the basic
assumption of EAB, but consistent with PCT.
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PCT then takes the position that events in the environment are only
the ultimate cause of behaviour overall because the subject would
not even exist in the environment if some events had not occurred.
The cause of existence is different from the cause of behavior -- i.e.,
specific actions. Not so?
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If I have a reference for "picking up mount Shasta with my hands",
the "environment" will "stop me" from doing such. To PCT the
"consequences" of my attempt are neither a "reinforcer" nor a
"punisher". PCT does recognize that somehow my "control failure
experience" is "learned". PCT does NOT predict that I will
immediately discontinue attempting to pickup mountains as a result
of this failure or any other. THE MEAR FACT OF THE EXISTANCE OF A
CONTROL FAILURE IS NOT A GUARANTEE OF BEHAVIOURAL CHANGE!
I think you're treating this on too intellectual a plane. If you picture
actually trying to pick up Mount Shasta with your hands as a REAL
PROCESS, I think you would discover a lot of reasons for reorganizing.
Your hands would be raw and bleeding; you would have ruptured tendons
and torn muscles all over your body; you would be in a state of chronic
and complete exhaustion. I predict that you would very quickly give up
this attempt because of extreme errors in other control systems,
including intrinsic systems that are involved in reorganization. It's
not the environment that stops you from having this goal; it's the felt
consequences of trying to carry it out. If you didn't mind bleeding and
aching and gasping for breath, nothing else could keep you from going
right on with the attempt. The environment doesn't care how you feel,
and it won't stop you from even suicidal efforts.
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Direct post:
Have you tried removing the "world model" code and running his
program?
Not yet, but I will.
There are some restrictions as to the compatibility between the
Amiga Pascal that I have and Turbo Pascal.
I understand that you have to take special precautions when using a
mouse as a control device on an Amiga to prevent time-sharing with other
processes, thus throwing the timing off. Are there other Amiga users out
there who can help with this?
I believe that I will have to rewrite the display routine to get a
useable display and there is something "funny" about keyboard
control attempts.
Right. My experiences with the Amiga led me to give up on it. To read a
keystroke and display the character on the screen takes a whole lot of
foreplay that, in the end, I wasn't willing to go through.
If you can get our programs to run on an Amiga, there might be others
who would be interested in seeing how you do it.
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Best,
Bill P.