pairing a previously neutral stimulus, such as the
sound of a cabinet being opened, with a stimulus that
generates an automatic response, such as presenting
meat, which automatically causes dogs to salivate, a
dog will come to associate the neutral stimulus with
the automatic response. After many pairings of the
neutral stimulus (sound) with the automatic stimulus
(meat), the response to the neutral stimulus, without
the presence of the automatic or unconditional stimu-
lus, produced salivation on its own. So, eventually,
just hearing the cabinet being opened was sufficient
for Pavlov’s dogs to begin salivating.
Under natural circumstances, food causes a dog
to salivate. This response is not learned or condi-
tioned so the food is called an unconditioned stimulus
while salivation is called an unconditioned response
because it occurs without any prior conditioning or
learning. After multiple pairings of the sound with
food, however, the sound alone would cause the dogs
to salivate. The sound has now become a conditioned
stimulus and the salivation is the conditioned re-
sponse because the dogs have been conditioned to
salivate to the sound.
Pavlov later found that he did not even need to
pair the conditioned stimulus (sound) directly with
the unconditioned stimulus (food) in order to cause
a conditioned response. He found that if he first con-
ditioned the dogs to salivate at the sound, and then
paired the sound with a wooden block, the dogs would
eventually salivate at the sight of the block alone even
though the block itself was never paired with the food.
This is called second-order conditioning; a second
neutral stimulus is paired with the conditioned stimu-
lus and eventually becomes a conditioned stimulus as
well.
In the 1920s John Watson, an American psychol-
ogist, applied the principles of classical conditioning
to human beings. He conducted an experiment on an
eleven-month-old baby, ‘‘Little Albert,’’ in which a
startling noise occurred as Albert was presented with
a white rat. Startling noises are unconditionally upset-
ting to infants, causing them to cry and crawl away,
while young children are not afraid of white rats.
After multiple pairings of the rat and the startling
noise, however, Little Albert developed a fear of the
rat, crying and crawling away even if the loud noise
did not occur. Watson thus showed that classical con-
ditioning also works with humans and that it works for
spontaneous emotional responses as well as physio-
logical ones.
Manipulating Classical Conditioning
Researchers have found many phenomena associ-
ated with classical conditioning. In some cases a neu-
tral stimulus very similar to the conditioned stimulus
will elicit the conditioned response even if it has never
been paired with the unconditioned stimulus before;
this phenomenon is known as generalization. An ex-
ample of generalization in Pavlov’s dogs would be the
dogs salivating to a sound of a different pitch than the
one that was paired with food. Discrimination train-
ing can eliminate generalization by presenting the
generalized stimulus without the unconditioned stim-
ulus (food).
It is possible to erase the effects of conditioning
by presenting the conditioned stimulus without the
unconditioned stimulus. In other words, after success-
fully conditioning a dog to salivate to a sound, experi-
menters can eliminate the effects of the conditioning
by presenting the sound many times without present-
ing the food. This process is called extinction. After
a period following extinction, the original condi-
tioned response might return again; this phenome-
non is called spontaneous recovery, and it can be
eliminated through a new series of extinction trials.Classical Conditioning and Psychopathology
Behavioral theorists believe that certain psycho-
logical disorders are a result of a form of classical con-
ditioning. Watson’s experiment on Little Albert
suggests that phobias might be learned through pair-
ing a neutral or harmless stimulus with an uncondi-
tionally frightening event, thus causing the person to
associate fear with the harmless stimulus. Treatment
for phobias involves extinguishing the association be-
tween fear and the neutral stimulus through so-called
systematic desensitization and flooding.
In systematic desensitization, patients are slowly
presented with the feared object in stages, beginning
with the least-feared situation and ending with a situ-
ation that provokes the most fear. The therapist
teaches the patient to remain relaxed as the feared
object approaches so eventually the patient associates
it not with fear but with calmness and relaxation. One
example is the case of Little Albert, in which Watson
attempted to extinguish the baby’s fear of the white
rat by giving him food (a stimulus that elicited plea-
sure) while showing the white rat. In this case, the
white rat ceases to be paired with a fear-inducing
stimulus and instead becomes linked to a pleasure-
inducing stimulus.
In flooding, the therapist attempts to alter the
pair that has been classically conditioned. In this case,
however, the patient agrees to be surrounded by the
fear-inducing stimulus and not attempt to escape the
situation. Flooding functions like extinction because
the stimulus is present without the aversive response,
so association weakens between the neutral stimulus
and the fear response. After a long period, the patient
ceases to be afraid of the stimulus.236 LEARNING