Developmental psychology.pdf

182 Learning and Information Processing
Figure 7.6
Extinction. As extinction trials
continued in Pavlov's laboratory, the
saliva drops were slower to appear
and fewer in number (Pavlov, 1927).
Trials
1
2
3
4
5
6
7
Latency
in
seconds
3
7
5
4
5
g
13
Drops
of Saliva
10
7
8
5
7
4
3
Extinction You may wonder how long the poor monk's punishment will last. If he
coughs continually without striking the cats again, they may become unafraid. The
devilish beasts may experience extinction, showing little or no fear at the sound of his
cough.
In extinction the conditioned stimulus is regularly presented without the unconditioned
stimulus, thus losing its acquired capacity. The conditioned response disappears.
This procedure is an intentional part of the process of differential conditioning.
When stimuli are not followed by the unconditioned stimulus, they lose whatever elic
king potential they may have had (Figure 7.6).
Number of trials
Series 1
Number of trials
Series 2
Number of trials
Series 3
Figure 7.7
Spontaneous Recovery. In series of
tests, the response reappears at a
much lower strength each time and
disappears more readily. Eventually, it
will not appear at all.
Spontaneous Recovery The monk's cough has now lost its power, and he has
temporarily lost his health. Transferred to the infirmary, sometime later he returns to
the monastery floor and, with a normal throat, coughs again. What will happen? In
all probability, the cats will scat, despite the earlier extinction and even without a new
beating in the bag. This outcome, called spontaneous recovery, is regarded as a forgetting
of extinction (Hill, 1981).
There is much evidence for spontaneous recovery, showing that extinction is
not necessarily permanent. After an interval of time, even with no new CS-US pairings,
a previously extinguished conditioned stimulus regains some of its earlier capacity,
eliciting the conditioned response. However, the recovery is weaker each time that
the conditioned stimulus is presented. In successive trials there is less and less response,
until eventually the conditioned response fails to appear at all (Figure 7.7).
Higher-Order Conditioning Now suppose that the fallen brother coughs once too
often. The watchful St. Ildefonso, noticing the cough's powerful effect on the animals,
forbids him to cough again. Is the monk's cause completely lost?
In approaching this problem assume that the cough has its full capacity and
that the monk has been eating alone with the cats. First, he claps his hands softly, then
coughs, and away the cats scat. He repeats this process again and again, and eventually