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Pavlovian Conditioning and its Concepts
DR DINESH RAMOO
Introduction
 In the late 1800s and early 1900s,
behaviourism was becoming a
dominant force within psychology.
Researchers
sought
simple,
mechanical explanations to displace
what they considered unscientific
accounts of thoughts, ideas, and other
mental processes.
 The mood of the time was ripe for the
theories of Ivan P. Pavlov, a Russian
physiologist who had won a Nobel
Prize in physiology in 1904 for his
research on digestion.
 As Pavlov continued his digestion research, one day he noticed that a dog would salivate or
secrete stomach juices as soon as it saw the lab worker who customarily fed the dogs.
 Because this secretion undoubtedly depended on the dog’s previous experiences, Pavlov called it
a ―psychological‖ secretion.
 He enlisted the help of other specialists, who then discovered that ―teasing‖ a dog with the sight
of food produced salivation that was as predictable and automatic as any reflex.
 Pavlov adopted the term conditional reflex, implying that he only conditionally (or tentatively)
accepted it as a reflex (Todes, 1997).
 However, the term has usually been translated into English as conditioned reflex, and that term
is now well established in the literature.
Pavlov’s Procedures
 Pavlov presumed that animals are born with certain automatic connections—
called unconditioned reflexes—between a stimulus such as food and a
response such as secreting digestive juices.
 He conjectured that animals acquire new reflexes by transferring a response
from one stimulus to another. For example, if a neutral stimulus (e.g., a
buzzer) always precedes food, an animal would respond to the buzzer as it
responds to food.
 The buzzer would begin to elicit digestive secretions. The process by which an
organism learns a new association between two paired stimuli—a neutral
stimulus and one that already evokes a reflexive response—is known as
classical conditioning, or Pavlovian conditioning. (It is called classical
because it has been known and studied for a long time.)
Pavlov’s Experiment

Pavlov used an experimental setup like the one in the figure (Goodwin, 1991).

First, he selected dogs with a moderate degree of arousal. (Highly excitable
dogs would not hold still long enough, and highly inhibited dogs would fall
asleep.)

Then he attached a tube to one of the salivary ducts in the dog’s mouth to
measure salivation. He could have measured stomach secretions, but
measuring salivation was easier.

Pavlov found that, whenever he gave a dog food, the dog salivated. The food
and salivation connection was automatic, requiring no training. Pavlov called
food the unconditioned stimulus, and he called salivation the unconditioned
response.

If a particular stimulus consistently, automatically elicits a particular
response, we call that stimulus the unconditioned stimulus (UCS), and the
response to it is the unconditioned response (UCR).
 Next Pavlov introduced a new stimulus, such as a metronome. Upon hearing the
metronome, the dog lifted its ears and looked around but did not salivate, so the
metronome was a neutral stimulus with regard to salivation.
 Then Pavlov sounded the metronome a couple of seconds before giving food to the
dog. After a few pairings of the metronome with food, the dog began to salivate as
soon as it heard the metronome (Pavlov, 1927/1960). We call the metronome the
conditioned stimulus (CS) because the dog’s response to it depends on the
preceding conditions—that is, the pairing of the CS with the UCS.
 The salivation that follows the metronome is the conditioned response (CR).
The conditioned response is simply whatever response the conditioned stimulus
begins to elicit as a result of the conditioning (training) procedure. At the start of
the conditioning procedure, the conditioned stimulus does not elicit a conditioned
response. After conditioning, it does.
At first
During training
After some number of repetitions
Conditioned and Unconditioned Response
 In Pavlov’s experiment the conditioned response (salivation) closely
resembled the unconditioned response (also salivation).
 However, in some cases it is quite different.
 For example, the unconditioned response to an electric shock includes
shrieking and jumping.
 The conditioned response to a stimulus paired with shock (i.e., a
warning signal for shock) is a tensing of the muscles and lack of activity
(e.g., Pezze, Bast, & Feldon, 2003).
Summary
 To summarise, the unconditioned stimulus (UCS), such as food, automatically elicits the unconditioned response
(UCR), such as salivating.
 A neutral stimulus, such as a sound, that is paired with the UCS becomes a conditioned stimulus (CS).
 At first this neutral stimulus elicits either no response or an irrelevant response, such as looking around.
 After some number of pairings of the CS with the UCS, the conditioned stimulus elicits the conditioned response
(CR), which usually resembles the UCR.
 The key difference between the CR and UCR is that the CS (conditioned stimulus) elicits the CR (conditioned
response) and the UCS (unconditioned stimulus) elicits the UCR (unconditioned response).
 All else being equal, conditioning occurs more rapidly if the conditioned stimulus is unfamiliar. For example, if
you heard a tone many times (followed by nothing) and then started hearing the tone followed by a puff of air to
your left eye, you would be slow to show signs of conditioning.
 Similarly, imagine two people who are bitten by a snake. One has never been near a snake before; the other has
spent years tending snakes at the zoo. You can guess which one will develop a fear of snakes.
Examples of Classical Conditioning
 Your alarm clock makes a faint clicking sound a couple of seconds
before the alarm goes off. At first the click by itself does not awaken you,
but the alarm does. After a week or so, you awaken as soon as you hear
the click.
Unconditioned
Stimulus
=
Alarm
Conditioned
Stimulus
=
Click

Unconditioned
Response
=
Awakening

Conditioned
Response
=
Awakening
Examples of Classical Conditioning
 You hear the sound of a dentist’s drill shortly before the unpleasant
experience of the drill on your teeth. From then on the sound of a
dentist’s drill arouses anxiety.
Unconditioned
Stimulus
=
Drilling
Conditioned
Stimulus
=
Sound of the drill

Unconditioned
Response
=
Tension

Conditioned
Response
=
Tension
Examples of Classical Conditioning
 A nursing mother responds to her baby’s cries by putting the baby to her
breast, stimulating the flow of milk. After a few days of repetitions, the
sound of the baby’s cry is enough to start the milk flowing.
Unconditioned
Stimulus
=
Baby sucking
Conditioned
Stimulus
=
Baby’s cry

Unconditioned
Response
=
Milk flow

Conditioned
Response
=
Milk flow
Examples of Classical Conditioning
 Note the usefulness of classical conditioning in each case: It prepares an individual
for likely events. In some cases, however, the effects can be unwelcome. For
example, many cancer patients who have had repeated chemotherapy or radiation
become nauseated when they approach or even imagine the building where they
received treatment (Dadds, Bovbjerg, Redd, & Cutmore, 1997).
Unconditioned
Stimulus
Conditioned
Stimulus
=
Chemotherapy or
radiation
=
Approaching the
building

Unconditioned
Response
=
Nausea

Conditioned
Response
=
Nausea
Try this
 Form an image of a lemon, a nice fresh juicy one. You cut it into slices
and then suck on a slice.
 Imagine that sour taste.
 As you imagine the lemon, do you notice yourself salivating?
 If so, your imagination produced enough resemblance to the actual sight
and taste of a lemon to serve as a conditioned stimulus.
The Phenomena of Classical Conditioning
Acquisition
 The process that establishes or strengthens a conditioned response is
known as acquisition.
 Once Pavlov had demonstrated how classical conditioning occurs,
curious psychologists wondered what would happen after various
changes in the procedures.
 Their
investigations have extended our knowledge of classical
conditioning.
Extinction
 Suppose I sound a buzzer and then blow a puff of air into your eyes. After a few
repetitions, you will start to close your eyes as soon as you hear the buzzer.
 Now I sound the buzzer repeatedly without the puff of air. What do you do?
 You will blink your eyes the first time and perhaps the second and third times,
but before long you will stop.
 This decrease of the conditioned response is called extinction.
 To extinguish a classically conditioned response, repeatedly present the
conditioned stimulus (CS) without the unconditioned stimulus (UCS).
 That is, acquisition of a response (CR) occurs when the CS predicts the UCS;
extinction occurs when the CS no longer predicts the UCS.
Extinction
 Extinction is not the same as forgetting. Both weaken a
learned response, but they arise in different ways.
 You forget during a long period with no relevant experience
or practice.
 Extinction occurs as the result of a specific experience—
perceiving the conditioned
unconditioned stimulus.
stimulus
without
the
Extinction
 Extinction does not erase the original connection between the CS and the UCS. We
can regard acquisition as learning to do a response and extinction as learning to
inhibit it.
 For example, suppose you have gone through original learning in which a tone
regularly predicted a puff of air to your eyes. You learned to blink your eyes at the
tone. Then you went through an extinction process in which you heard the tone
many times but received no air puffs.
 You extinguished, so the tone no longer elicited a blink. Now, without hearing a
tone, you get another puff of air to your eyes. As a result, the next time you hear the
tone, you will blink your eyes. Extinction inhibited your response to the CS (here, the
tone), but a sudden puff of air weakens that inhibition (Bouton, 1994).
Spontaneous Recovery
 Suppose you are in a classical-conditioning experiment.
 At first you repeatedly hear a buzzer sound (CS) that precedes a puff of air to your
eyes (UCS).
 Then the buzzer stops predicting an air puff. After a few trials, your response to the
buzzer extinguishes.
 Now, suppose you sit there for a long time with nothing happening and then
suddenly you hear another buzzer sound.
 What will you do? Chances are, you will blink your eyes at least slightly.
Spontaneous recovery is this temporary return of an extinguished response
after a delay. Spontaneous recovery requires no additional CS–UCS pairings.
Spontaneous Recovery
 Why does spontaneous recovery take place?
 Think of it this way: At first the buzzer predicted a puff of air to your
eyes, and then it didn’t.
 You behaved in accordance with the more recent experiences.
 Hours later, neither experience is much more recent than the other, and
the effects of the original acquisition are almost as strong as those of
extinction.
Stimulus Generalisation
 Suppose a bee stings you. You quickly learn to fear bees.
 Now you see a similar large insect, such as a wasp or hornet. Will you
fear that too? You probably will.
 However, you probably will not show any fear of ants, fleas, or other
insects that don’t resemble bees.
 The more similar is a new stimulus to the conditioned stimulus, the
more likely you are to show a similar response.
Stimulus Generalisation
 Stimulus generalization is the extension
of a conditioned response from the training
stimulus to similar stimuli.
 This
definition
may
sound
pretty
straightforward, but psychologists find it
difficult to specify exactly what ―similar‖
means (Pearce, 1994).
 For example, after a bee stings you, you might
fear the sound of buzzing bees when you are
walking through a forest but not when you
hear the same sounds as part of a nature
documentary on television. Your response
depends on how similar the total
configuration of stimuli is to the set on which
you were trained, and that similarity is hard
to measure.
Discrimination
 Suppose your alarm clock makes one kind of click when the alarm is about to
ring but you hear a different kind of click at other times.
 You will learn to discriminate between these two clicks: You will respond
differently because the two stimuli predicted different outcomes.
 You awaken when you hear one click but not when you hear the other.
 Similarly, you discriminate between a bell that signals time for class to start
and a different bell that signals a fire alarm.
 You might learn to discriminate between a poisonous snake and a similar
looking, harmless snake.
Classical Conditioning
EXAMPLES
Drug Tolerance
 Classical conditioning shows up in places you might not expect. One example is
drug tolerance: Users of certain drugs experience progressively weaker effects
after taking the drugs repeatedly.
 Some long-time users inject more heroin or morphine into their veins than it would
take to kill a nonuser.
 Consequently, the users crave larger and larger amounts of the drug.
 Drug tolerance results partly from automatic chemical changes that occur in cells
throughout the body to counteract the drug’s effects (Baker & Tiffany, 1985).
 It also depends partly on classical conditioning.
 Consider: When drug users inject themselves with morphine or heroin,
the drug injection procedure is a complex stimulus that includes the
time and place as well as the needle injection.
 This total stimulus predicts a second stimulus, the drug’s entry into the
brain, which triggers a variety of body defences against its effects—for
example, changes in hormone secretions, heart rate, and breathing rate.
1st Stimulus
Injection
Procedure
2nd Stimulus
Drug enters
brain
3rd Stimulus
Body’s
Defences
 Whenever one stimulus predicts a second stimulus that produces an
automatic response, classical conditioning can occur. The first stimulus
becomes the CS, the second becomes the UCS, and its response is the
UCR.
 So we can relabel as follows:
CS
Injection
Procedure
UCS
Drug enters
brain
UCR
Body’s
Defences
 If conditioning occurs here, what would be the consequences? Suppose the CS (drug
injection) produces a CR that resembles the UCR (the body’s defences against the drug).
 As a result, as soon as the person starts the injection, before the drug enters the body, the
body is already mobilizing its defences against the drug.
 Therefore, the drug will have less effect—the body develops tolerance.
 Shepard Siegel (1977, 1983) conducted several experiments to confirm that classical
conditioning occurs during drug injections. That is, after many drug injections, the injection
procedure by itself evokes the body’s antidrug defences:
CS
Injection Procedure
CR
Body’s defences
 One prediction was this: If the injection procedure serves as a conditioned stimulus,
then the body’s defence reactions should be strongest if the drug is administered in
the usual way, in the usual location, with as many familiar stimuli as possible. (The
whole experience constitutes the conditioned stimulus.)
 The evidence strongly supports this prediction for a variety of drugs (Marin, Perez,
Duero, & Ramirez, 1999; Siegel, 1983).
 For example, a rat that is repeatedly injected with alcohol develops tolerance,
improving its balance while intoxicated. But if it is now tested in the presence of
loud sounds and strobe lights, its balance suffers.
 Conversely, if it had practiced its balance while intoxicated in the presence of loud
sounds and strobe lights, its balance suffers if it is tested without those stimuli
(Larson & Siegel, 1998). In short, the tolerance depends on learning.
 Why do some people die of a drug overdose that is no larger than the
dose they normally tolerate?
 They probably took the fatal overdose in an unfamiliar setting.
 For example, someone who is accustomed to taking a drug at home in
the evening could suffer a fatal reaction from taking it at a friend’s
house in the morning.
 Because the new setting did not serve as a CS, it failed to trigger the
usual drug tolerance.
Emotional Conditioning Without Awareness
Introduction
 In many situations conditioning occurs fastest when people are aware of the
connection between the CS and UCS (Knuttinen, Power, Preston, &
Disterhoft, 2001). (With laboratory animals, it is hard to ask!)
 However, emotional responses sometimes become conditioned without
awareness. The implications are far-reaching.
 We shall examine one study in detail. In some ways this discussion will seem
out of place: The whole idea of discussing attitudes, emotions, and so forth is
contrary to the customs of radical behaviourism.
 Nevertheless, we see here how other psychologists have taken the idea of
classical conditioning and applied it more broadly.
Hypothesis
 People will form favourable attitudes toward items paired with
something they like and unfavourable attitudes toward items paired
with something they dislike, even if they are not aware of the connection
(Olson & Fazio, 2001).
Method
 Forty-five female college students viewed a series of slides. Most included a Pokémon image, although a few
were blank.
 Most of those with a Pokémon also included another picture or a word. Each student’s task was to look for a
particular ―target‖ Pokémon and press a computer key whenever she saw it, ignoring all the other pictures
and words.
 Most of the other Pokémon images were paired with neutral words and pictures, but one of them was
always paired with something likable (e.g., a picture of tasty food or the word ―excellent‖), and one was
always paired with something negative (e.g., a picture of a cockroach or the word ―terrible‖).
 After viewing all the slides repeatedly, each student was asked to look at all the Pokémon images (by
themselves) and rate how pleasant or unpleasant they were.
 They were also asked whether they remembered what other items had paired with each Pokémon.
Results
 On the average the women gave a higher pleasantness rating to the
Pokémon that had been associated with favourable words and pictures
and lower ratings to the one associated with unfavourable words and
pictures.
 However, they did not remember what words or pictures had been
associated with each Pokémon. (They hadn’t been told to remember
those pairings, and they didn’t.)
Interpretation
 These results show classical conditioning can alter people’s emotional responses to
pictures, even though people did not notice them enough to report explicit
memories.
 Additional research has shown conditioning of other kinds of emotional responses.
 In one study people saw words paired with pictures of faces, some of which were
smiling or frowning.
 For some of the participants, personally relevant words (their name, their birth date,
etc.) were consistently paired with smiling faces.
 As a result of this pairing, they showed increases in several measures of self-esteem!
Evidently, the pairings enhanced emotional responses to reminders of the
participants themselves (Baccus, Baldwin, & Packer, 2004).
Summary
 Classical conditioning. Ivan Pavlov discovered classical conditioning,
the process by which an organism learns a new association between two
stimuli that have been paired with each other—a neutral stimulus (the
conditioned stimulus) and one that initially evokes a reflexive response
(the unconditioned stimulus).
 The organism displays this association by responding in a new way (the
conditioned response) to the conditioned stimulus.
 Extinction. After classical conditioning has established a conditioned
response to a stimulus, the response can be extinguished by repeatedly
presenting that stimulus by itself.
 Spontaneous recovery. If the conditioned stimulus is not presented at all for
some time after extinction and is then presented again, the conditioned
response may return to some degree. That return is called spontaneous
recovery.
 Stimulus generalization. An individual who learns to respond to one stimulus
will respond similarly to stimuli that resemble it. However, it is difficult to
specify how we should measure similarity.
 Discrimination. If one stimulus is followed by an unconditioned stimulus and
another similar stimulus is not, the individual will come to discriminate
between these two stimuli.
 Emotional conditioning without awareness. In many situations conditioning
is strongest if the learner is aware of the CS–UCS connection. However,
emotional responses can be conditioned even if the learner is not aware of the
connection.
 Drug tolerance. Drug tolerance is partly a form of classical conditioning in
which the drug administration procedure comes to evoke defensive responses
by the body.
Questions?
 At the start of training, the CS
 At the start of training, the CS
elicits ___ and the UCS elicits
___.
elicits no response and the UCS
elicits the UCR.
 After many repetitions of the CS
 After many repetitions of the CS
followed by the UCS, the CS elicits
___ and the UCS elicits ___.
followed by the UCS, the CS elicits
CR and the UCS elicits UCR.
Some useful reading
 Bandura, A. (1986). Social foundations of thought and action. Upper
Saddle River, NJ: Prentice Hall. A review of social learning by its most
influential investigator.
 Kroodsma, D. (2005). The singing life of birds. New York: Houghton
Mifflin. Thorough account of research on a fascinating kind of animal
learning.
 Staddon, J. (1993). Behaviorism. London: Duckworth. A critique of
both the strengths and weaknesses of Skinner’s views.
References
Baccus, J. R., Baldwin, M. W., & Packer, D. J. (2004). Increasing implicit self-esteem through classical conditioning.
Psychological Science, 15, 498–502. (6)
Baker, T. B., & Tiffany, S. T. (1985). Morphine tolerance as habituation. Psychological Bulletin, 92, 78–108. (6)
Bouton, M. E. (1994). Context, ambiguity, and classical conditioning. Current Directions in Psychological Science, 3,
49–53. (6)
Dadds, M. R., Bovbjerg, D. H., Redd, W. H., & Cutmore, T. R. H. (1997). Imagery in human classical conditioning.
Psychological Bulletin, 122, 89–103. (6)
Knuttinen, M.-G., Power, J. M., Preston, A. R., & Disterhoft, J. F. (2001). Awareness in classical differential eyeblink
conditioning in young and aging humans. Behavioral Neuroscience, 115, 747–757. (6)
Larson, S. J., & Siegel, S. (1998). Learning and tolerance to the ataxic effect of ethanol. Pharmacology Biochemistry
and Behavior, 61, 131–142. (6)
References
Marin, R. H., Perez, M. F., Duero, D. G., & Ramirez, O. A. (1999). Preexposure to drug administration context blocks the
development of tolerance to sedative effects of diazepam. Pharmacology Biochemistry and Behavior, 64, 473–477. (6)
Olson, M. A., & Fazio, R. H. (2001). Implicit attitude formation through classical conditioning. Psychological Science, 12, 413–417.
(6)
Pavlov, I. P. (1960). Conditioned reflexes. New York: Dover. (Original work published 1927) (6)
Pezze, M. A., Bast, T., & Feldon, J. (2003). Significance of dopamine transmission in the rat medial prefrontal cortex for conditioned
fear. Cerebral Cortex, 13, 371–380. (6)
Siegel, S. (1977). Morphine tolerance as an associative process. Journal of Experimental Psychology: Animal Behavior Processes, 3,
1–13. (6)
Siegel, S. (1983). Classical conditioning, drug tolerance, and drug dependence. Research Advances in Alcohol and Drug Problems, 7,
207–246. (6)
Todes, D. P. (1997). From the machine to the ghost within. American Psychologist, 52, 947–955. (6)