314 Chapter 9 Learning and Conditioning
Biology and Conditioned Fears. Back when
John Watson was using counterconditioning to
help young Peter overcome his fear of rabbits,
techniques for understanding the biological basis
of classical conditioning were limited. But today,
with technology and a better understanding of the
brain, scientists can explore methods for helping
people overcome debilitating fears in ways that
Watson could scarcely have imagined.
The amygdala plays a central role in the
conditioning of fear, in part because of a receptor
for the neurotransmitter glutamate. Giving rats
a drug that blocks this receptor prevents extinc-
tion of a conditioned fear, whereas giving a drug
that enhances the receptor’s activity speeds up
extinction (Walker et al., 2002). Inspired by these
results, researchers set out to discover whether
the receptor-enhancing drug (which is safe in
humans) could help people with a conditioned
phobic fear of heights (Davis et al., 2005). Using a
double-blind procedure, they gave the drug to 15
people with the phobia and a placebo to 15 others.
All participants then underwent two therapy ses-
sions in which they donned virtual reality goggles
and “rode” a glass elevator to progressively higher
floors in a virtual hotel—an incredibly scary thingended early, Watson and Rayner had no opportu-
nity to reverse the conditioning. However, Watson
and Mary Cover Jones did reverse another child’s
conditioned fear—one that was, as Watson put it,
“home-grown” rather than psychologist-induced
( Jones, 1924). A 3-year-old named Peter was
deathly afraid of rabbits. To reverse Peter’s fear,
Watson and Jones used a method called counter-
conditioning, in which a conditioned stimulus is
paired with some other stimulus that elicits a re-
sponse incompatible with the unwanted response
(see Figure 9.5). In this case, a rabbit (the CS) was
paired with a snack of milk and crackers, and the
snack produced pleasant feelings that were incom-
patible with the CR of fear.
At first, the researchers kept the rabbit some
distance from Peter, so that his fear would re-
main at a low level. Otherwise, Peter might have
learned to fear milk and crackers! Then gradually,
over several days, they brought the rabbit closer
and closer. Eventually Peter learned to like rabbits
and was even able to sit with the rabbit in his lap,
playing with it with one hand while he ate with
the other. A variation of this procedure, called sys-
tematic desensitization, was later devised for treat-
ing phobias in adults (see Chapter 12).counterconditioning
In classical conditioning,
the process of pairing a
conditioned stimulus with
a stimulus that elicits a
response that is incom-
patible with an unwanted
conditioned response.
CSCRUSURNeutral CS
stimulusUSURFigURE 9.4 The Creation of a Fear
In the Little Albert study, noise from a hammer striking a steel bar was an unconditioned stimu-
lus for fear (left). When a white rat, a neutral stimulus, was paired with the noise (center), the
rat then became a conditioned stimulus for fear (right).USURCSCRCS USURCSNew CRFigURE 9.5 The Counterconditioning of a Fear
Three-year-old Peter had acquired a conditioned fear of rabbits. To countercondition this fear, the researchers paired a rabbit (the CS)
with a snack of milk and crackers (a US), which produced feelings of pleasure that were incompatible with the conditioned response of
fear. Eventually, Peter felt as comfortable with the rabbit as with the crackers.