Logan:  Basic Principles of Learning

                      CLASSICAL CONDITIONING

          If an unconditional stimulus (US) that reliably elicits an 
          unconditional response (UR) is regularly preceded by an
          antecedent stimulus (S), a conditioned response (CR)
          resembling the UR will come to occur before the US.

    This principle was first systematically studied by Pavlov in Russia and his
work became influential in the United States shortly after the First World War.
He used dogs as subjects and salivaton as an unconditioned ALIMENTARY response 
to food and a DEFENSE response to acid-in-the-mouth.  (An unlearned reflex is 
called and "unconditioned response" and is symbolized "UR"; its eliciting 
stimulus is called an "unconditioned stimulus" and is symbolized "US").  
In either case, salivation could be conditioned to any of a variety of 
antecedent (conditioned) stimuli (S or CS) such as a flashing light or the 
beat of a metronome.  (When a response is elicited by a stimulus that has been 
paired with a US, it is called a "conditioned response" and is symbolized (CR).
Among the most common responses studied in the U. S. Is the eye blink
elicited by a puff of air to the eye of human subjects.  Any reflex response 
(change in heart rate, sweating in the palm, sleeping, awakening, leg flexion, 
etc.) can be conditioned to any initially neutral stimulus that is
detectable by the organism, at least in all mammals.

     The most important feature of the classical conditioning paradigm is that 
the scheduled events occur without regard to the behavior of the organism.  
Whether or not a CR occurs has no bearing on what happens.  However, this fact 
does not necessarily mean that there is no functional significance to the CR.  
It is quite reasonable to argue that the CR is beneficial because dry food 
tastes better, and acid hurts less, in a moist mouth than a dry one.  In sum, 
although the organism cannot affect the occurrence or nonoccurrence of events 
in classical conditioning, it is possible for the CR to affect the way those 
events affect the organism.

     Although there is no argument about the empirical Principle of Classical 
Conditioning, there is a difference of opinion as to whether the organism
learns a cognitive S-S association between the two stimuli or a behavioristic 
S-R association between the antecedent stimulus and the UR.  According to
the former approach, the organism comes to expect the occurrence of the US and 
behaves adaptively in an anticipatory fashion.  According to the latter
approach, the CR is directly elicited by the antecedent S.  Most embarrassing 
to the cognitive view are the facts that CR's cannot be successfully
inhibited voluntarily and often occur without conscious awareness.  Most
embarrassing to the behavioristic view are the facts that the CR is usually 
different in detail from the UR and conditioning can be obtained even if
the UR is blocked by a drug such as curare during conditioning.  Although 
theorists have been inclined to adopt one or the other approach, it is
perfectly possible that both types of associations are formed in classical 
conditioning.

     A very important extension of the Principle of Classical Conditioning is 
HIGHER-ORDER CONDITIONING.  In place of a US that reflexively elicits a UR, it 
is possible to use an S that has a well-established CR to condition the CR to 
another S.  For example, after salivation has been conditioned to a
metronome, one can pair a light with the metronome, now without food being 
given.  As long as salivation is elicited by the metronome, it will be
effective in conditioning salivation to the light.  Then, in principle, the 
light could be used to condition salivation to yet another S.  However, there 
are practical limits to how far higher-order conditioning can be extended, 
because the absence of food ultimately leads to extinction of responding to 
all stimuli.

     Classical conditioning is not a peculiar laboratory demonstration.  Very 
much on the contrary, such responses are common in much of our everyday 
behavior.  Of greatest practical significance is that most of our feelings, 
emotions, and attitudes are molded by this very fundamental principle.  The 
fear that you may have of an upcoming examination, the excitement you may feel 
before an important ball game, the relaxation that comes with thoughts of
home and family, and the inner pressures we call our conscience, are products 
of classical conditioning.


TERMS: Association, awareness, classical conditioning, extinction, 
higher-order conditioning, inhibition, response (alimentary,
antecedent, conditioned, defense, unconditioned), stimulus (antecedent, 
conditioned, neutral, unconditioned)