[From Bill Powers (951201.1430 MST)]
Bruce Abbott (951201.1510 EST) --
yes, you are misreading it. Pigeons (without training) peck at
seeds etc. they see on the ground and sieze them. (They soon learn
which visual objects usually turn out to be palatable and which do
not.) Through classical conditioning, another stimulus, not
necessarily resembling the US in any way, triggers the same
response.
Wait a minute. Let's see if we can't get explicit about what you're
proposing here.
1. "Pigeons peck at seeds" you say. "Peck" I understand, and "seeds" I
understand, but what does it mean to say that the pigeons peck AT the
seeds? If a seed is an unconditional stimulus, is the effect of the
stimulus connected to the muscles that create pecking so that the
pecking response brings the beak near or on the seed that stimulated it
(wherever it happens to be) instead of somewhere else? Is this
phenomenon accounted for in EAB (remembering that it is said to be
innate)?
2. When you say "through classical conditioning" another stimulus comes
to trigger the "same response," are you saying that another stimulus
acts on the nervous system to have the same effect that a seed has; that
is, triggering a pecking action that is aimed at a seed? Or does it now
trigger the same response but in such a way that it is aimed at the new
stimulus instead of a seed?
3. Exactly what is it _about_ classical conditioning that produces this
result? Are you sure that you're not just naming this effect "classical
conditioning" and then using the name to explain the effect?
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Where a keypeck is required (operant conditioning), food cannot be
expected in the absence of the response and classical conditioning
to the illuminated key per se will not occur.
Is the first phrase, "food cannot be expected in the absence of the
response" an explanation of the second one, "classical conditioning ...
will not occur?" Or are you only saying that classical conditioning is
defined as the case where food can occur when the key is illuminated and
without any pecking, and not as the case where pecking is required to
produced food?
If the first phrase is meaningful, what does the term "expected" mean?
Do the pigeon's expectations play a role in differentiating between
classical and operant conditioning?
So no, all new experiments are not analyzed with that in mind,
nor need they be. Once it is recognized that a particular response
_can_ be classically conditioned, one can predict under which
conditions such conditioning is to be expected.
OK. If I understand you correctly, if food is produced by a peck on a
key, classical conditioning is not predicted, but if the key is
illuminated and food follows even without a keypeck, classical
conditioning is predicted. What happens during the time that the key is
illuminated but before the noncontingent delivery of food occurs? Does
the food appear immediately upon a keypeck when the key is illuminated?
I have to presume it does, because otherwise the food would appear at
the end of the delay whether or not there was a peck. And if so, is not
the delivery of food contingent on the keypeck just as in operant
conditioning? I fail to see any rigorous distinction between the
classical and operant phenomena in autoshaping.
It seems to me that the so-called classical conditioning doesn't work
properly. Why shouldn't it produce pecks wherever they happen to be
occurring when the light turns on? Those pecks, just as surely as pecks
on the key, will be followed by delivery of food. If the pigeon pecks 6
inches to the left of the key each time the light turns on, food will
appear. So if the light turns on, the pigeon should peck 6 inches to the
left of the key. How does classical conditioning ever get it to peck ON
the key?
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Guessing about reinforcers is a lot like guessing about controlled
perceptions, and in both cases a good model cannot be built until
the empirical work has identified those things. But control theory
is fundamental: tell me what perception is under control, and I'll
tell you what sorts of things can serve as the "reinforcers."
Fine, as far as it goes, but this doesn't differentiate between
reinforcers and controlled variables completely enough. A reinforcer is
said to increase the probability of the response that created it. A
controlled variable is maintained at a specific level by _variations_ in
the actions that affect it. The difference can be seen only in the
presence of independent disturbances of the controlled variable or
reinforcer. There is confusion between controlled variables and
reinforcers in the normal operant conditioning experiment only because
independent disturbances are kept from occurring.
If you introduce disturbances in an operant conditioning experiment, you
will no longer be able to define a reinforcer, because no state of the
variable in question will increase the probability of any particular
response. In fact, the responses can be made independent of the state of
the reinforcer, yet control will continue.
I have repeatedly brought this point up, without a comment from you. If
you will promise to discuss this point, I will work up a simple
experiment to illustrate it. But if you're just going to let it slide
past again, I won't bother. What about it?
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Best,
Bill P.