[lit-ideas] Re: Geary-Pavlov Experiment/Garcia's Rats vs. Pavlov's Dogs
- From: Donal McEvoy <donalmcevoyuk@xxxxxxxxxxx>
- To: lit-ideas@xxxxxxxxxxxxx
- Date: Sun, 16 Jan 2011 17:26:25 +0000 (GMT)
What is presented as "Pavlov's Dog" is a misinterpretation (by Pavlov, who
should have stuck to merringue-based desserts, and others) of certain
experiments. In effect, Pavlov's experiments are put forward as demonstrating
the truth of an associationist psychology a la Hume and Locke. But the
experiments permit a non- or anti-associationist interpretation, and therefore
the experiments do not demonstrate which of the two interpretations is correct.
A better way into this, perhaps, is not Pavlov's work, which permits rival
interpretations, but the work of John Garcia which undermines the
associationist interpretation. In Garcia's experiments, as explained by Martin
Seligman:-
"Every time his rats licked at their drinking spouts, they tasted saccharin,
and a burst of light and noise came on. This is called a _compound CS_ -
bright, noisy saccharin water. Then a burst of X rays occurred. Within a few
hours the rats were sick to their stomachs. When the rats recovered, Garcia
tested the elements of the compound CS separately to see what the rats had
learned to fear. They now hated saccharin, but they were completely unperturbed
by the bright noise. When they got sick, they blamed it on the taste and
ignored everything else.
"Maybe they had just failed to notice the bright noise duing conditioning? So
Garcia counterbalanced the experiment. Other rats were given the same bright,
noisy saccharin paired now with foot shock instead of stomach illness. What did
they learn? They now cringed in fear of bright noise, but they still loved
saccharin. When they suffered pain, they blamed it on the bright noise and
ignored the taste.
"So the bright noise and the saccharin were noticeable, but only the taste
became aversive when the rats became nauseated, and only the bright noise
became aversive when the rats suffered pain. How could this be?"
Seligman points out difficulties in fitting this within the framework of
Pavlovian conditioning ['PC']. These include:- PC is not selective whereas the
rats are selective as to what they associate with what; PC depends on short
time gaps whereas the rats 'associated' "saccharin" and the nausea they felt
hours later; PC depends on repetition whereas the rats were put off the food
after a single episode of post-food nausea; PC is meant to involve 'awareness'
but rats nauseated while anaesthetised woke up with an aversion to saccharin;
PC is meant to be as easily extinguished but this is not true of the rat's
'learned' aversions.
Seligman concludes, however, that all these difficulties "_can_ be reconciled
with Pavlovian conditioning, because evolution is at work". Be that as it may,
Popper argues that PC, and its arc of the conditioned/conditional reflex, is a
misinterpretation that cannot be easily reconciled with a Darwinian view of
evolution: instead it is a Lamarckian and an inductivist misinterpretation.
It might be tempting (particularly to those pre-conditioned or predisposed that
way) to see the rats' aversive reactions as a special subset of Pavlovian
conditioning that have arisen given their usefulness as a survival mechanism
(survival mechanisms for avoiding poisonous foods or electrical shocks).
But for a thinker like Popper the correct conclusion is that Garcia's rats give
us the better clue to the general picture, not Pavlov's dogs; and that Pavlov's
dogs reactions are a special subset of the model of Darwinian trial-and-error
learning, not associationist learning, that better accounts for the rats' and
the dogs' behaviour.
Absent poisonous after-effects, which it would be evolutionarily useful to
learn from, and bearing in mind the gradual winnowing from the gene-pool of
creatures that are over-apt to eat poisonous things (a winnowing so successful
that other creatures can take advantage and avoid being eaten by dissembling
that they are poisonous or harmful to eat):- creatures like dogs and rats would
be well-advised to eat whenever the opportunity arises and will do so provided
prior disposition or past experience does not cast the food as harmful.
As dogs need to salivate to help their eating, evolution will favour a great
readiness to salivate in order to that the dog be able to take advantage of any
eating opportunity: this predisposition to salivate at the slightest
expectation of an eating opportunity explains why dogs will readily salivate if
the person who normally feeds them turns up or if it is normal 'feeding time'
etc. _This predisposition is not the result of PC rather what looks like PC is
a result of this predisposition_.
The same is true of the rats. They are not conditioned as per PC: rather they
are evolutionarily prepared both to eat and to avoid poison, and evolutionarily
prepared with mechanisms for differentiating what will nourish them and what
will poison them - one such mechanism is a learning-mechanism where they
'learn' from post-feed nausea to avoid the kind of food in question. This
learning is not associationist in the sense of PC but is better understood as
an imperfect 'trial-and-error' mechanism that has evolved by natural selection.
Donal
Enjoying Mozart
London
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