Classical Conditioning Module 18
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Learning
•  Unlike most animals, we do not have a genetic blueprint for life. –  E.g., Migrating birds know where they are supposed to go and how to go. •  Much of what we do, we learn from experience. 2
Learning
  Learning is a relatively permanent change in behavior, or behavior potential, that occurs as the result of practice or experience.
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Learning
1.  Classical (or Pavlovian) conditioning
• 
Associate two stimuli • 
Associate a response and its consequence, and repeat acts followed by rewards and avoid acts followed by punishments
2.  Operant conditioning
3.  Observational learning
• 
We learn from others’ experiences and examples (e.g., a kid modeling his father dealing with a problem) 4
Classical Conditioning
•  Associative Learning
–  learning that two events occur together
•  Conditioning –  is the process of learning associations.
•  We learn by association: Our minds naturally connect events that occur in sequence
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But first non-associative simple
forms of learning
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Habituation
•  Habituation is an extremely simple form of
learning, in which an animal, after a period
of exposure to a stimulus, stops
responding.
Habituation of the Startle Response in Rats
http://go.owu.edu/~deswartz/videos/habituation.mov
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Habituation
•  E.g., after 10 weak
tactile stimulations,
animal shows little or
no reaction.
•  Duration of the
memory for habituation
is a function of
repetition.
Kandel, 2001
Bear et al, 2007
Sensitization
• 
Sensitization is an increase in the
response to an innocuous stimulus
when that stimulus occurs after a
punishing stimulus.
• 
When Aplysia receives a shock to its
tail, its reaction to siphon stimulation is
substantially strengthened: it
withdraws its gill more completely.
• 
A single shock to the tail results in
short term memory that lasts for
minutes. 4-5 shocks produce a long
term memory that lasts two or more
days. Further training, results in
memory that lasts for weeks.
Sensitization
Classical Conditioning
Ideas of classical conditioning originate from old philosophical theories (Aristotle, John Locke, David Hume). However, it was the Russian physiologist Ivan Pavlov who elucidated classical conditioning. His work provided a basis for later behaviorists like John Watson.
Ivan Pavlov (1849-­‐‑1936)
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Nature vs. Nurture
Behaviorism
  An approach to psychology that emphasizes the study of observable behavior and the role of the environment as a determinant of behavior.
“Give me a dozen healthy infants, well-­‐‑formed, and my own special world to bring them up in, and I’ll guarantee to take any one at random and train him to be any type of specialist I might select -­‐‑ doctor, lawyer, artist, merchant-­‐‑
chief, and yes, beggar-­‐‑man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors.”
J. B. Watson, 1928
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Classical Conditioning
•  Ivan Pavlov
  Russian physiologist
  Nobel prize winner (for his work on physiology of digestion)
  Conditioning was just an accident: dogs salivating before food was given
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Classical Conditioning: Terminology
  Unconditioned Stimulus (UCS)
  stimulus that unconditionally-­‐‑-­‐‑automatically and naturally-­‐‑-­‐‑triggers a response
  Unconditioned Response (UCR)
  unlearned, naturally occurring response to the unconditioned stimulus
 salivation when food is in the mouth 22
  Conditioned Stimulus (CS)
  originally irrelevant (neutral) stimulus that, after association with an unconditioned stimulus, comes to trigger a conditioned response
  Conditioned Response (CR)
  learned response to a previously neutral conditioned stimulus (e.g., salivating to tone after learning)
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Conditioning Process
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Conditioning Process
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Conditioning Process
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An Example: Birds
An MIT student spent an entire summer going to the Harvard football field every day wearing a black and white striped shirt (referee shirt), walking up and down the field for ten or fifteen minutes throwing bird seed all over the field, blowing a whistle and then walking off the field. At the end of the summer, it came time for the first Harvard home football game, the referee walked onto the field and blew the whistle, and the game had to be delayed for a half hour to wait for the birds to get off of the field.
The student wrote his thesis on this, and graduated. 29
Processes of Conditioning
  Acquisition
  Extinction
  Spontaneous Recovery
  Stimulus Generalization/ Discrimination 30
Acquisition
  Acquisition is the initial learning stage in classical conditioning in which an association between a neutral stimulus and an unconditioned stimulus takes place.
  The time in between the two stimuli should be about half a second. Is it really? More on this later!
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Stimulus-Response (S-R)
Learning
Classical Conditioning:
TONE
Airpuff
Sensory Neurons
Large EPSP
AIR PUFF
TONE
BLINK
Motor
Neuron
Small EPSP
S-R Learning: Classical
Conditioning
•  Classical Conditioning:
TONE
Airpuff
Sensory Neurons
AIR PUFF
BLINK
TONE
TONE
TONE
Motor
Neuron
Classical Conditioning Learning Curve
•  The more
often the
pairing
occurs, the
stronger the
response
•  Early
pairings are
more
important
than later
pairings
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Classical Conditioning
•  Classical conditioning of emotional
responses.
Demonstration
Timing of CS before UCS
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Extinction
  Diminishing of a CR
  When the US (food) does not follow the CS (tone), CR (salivation) begins to decrease and eventually causes extinction.
Example:
Ring the bell but do not present the food... When done repeatedly.. The learned association will become weaker and weaker...
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Spontaneous Recovery
After a rest period, an extinguished CR (salivation) spontaneously recovers.
The CR reappears in a weaker form.
But if the CS (tone) persists alone, the CR becomes extinct again.
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Spontaneous Recovery
Spontaneous recovery suggests that extinction does not eliminate the conditioned response but rather supresses it.
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Second (Higher) Order
Conditioning
•  Once a stimulus has been developed as a
CS, it can then serve as a US to develop a
second CS
•  This is known as second-order conditioning
•  This second CS can then serve as a US to
develop still another CS (third-order), etc.
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Second (Higher) Order
Conditioning
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Classical Conditioning
  Generalization
  Tendency to respond to stimuli similar to the CS
  Can be adaptive: children who are taught to fear moving cars on street respond similarly to trucks and motorcycles on the street
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Classical Conditioning
  Discrimination
  the learned ability to distinguish between a CS and other stimuli that do not signal a UCS
  E.g., fear pitbulls but not golden retrievers
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Extending Pavlov’s Understanding
Pavlov and Watson considered consciousness, or mind, unfit for the scientific study of psychology. However, they underestimated the importance of cognitive processes and biological constraints.
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Cognitive Processes
Later behaviorists suggested that animals learn the predictability of a stimulus, meaning they learn expectancy or awareness of a stimulus.
Thought/expectation of the CS-­‐‑UCS link macers for conditioning
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Cognitive Processes: Blocking
Rescorla & Wagner (1972) showed that animals learn the predictability of an event.
If a shock always is preceded by a tone, and then may also be preceded by a light that accompanies the tone, a rat will react with fear to the tone but not to the light.
The tone is a becer predictor and the more predictable the association, the stronger the CR.
It is as if the animal learns an expectancy, an awareness of how likely it is that the US will occur.
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Cognitive Processes
Some therapies for alcohol dependency administer a nauseating drug that accompanies alcohol.
If classical conditioning was simply a result of “stamping in” stimulus associations, one would expect alcohol to be associated with nausea and thus its avoidance.
But the awareness that the nausea is induced by the drug, not the alcohol, often weakens the association between drinking alcohol and feeling sick.
Thus, beliefs macer even for very simple form of learning such as classical conditioning.
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Biological Predispositions
Pavlov and Watson believed that laws of learning were similar for all animals. Therefore, a pigeon and a person do not differ in their learning.
According to this view, every “neutral” stimulus should have the same degree of associability with the unconditioned stimulus.
However, behaviorists later suggested that learning is constrained by an animal’s biology. 49
Biological Predispositions
Taste aversion in rats (Garcia & Koelling, 1966): Rats are biologically prepared to learn associations between the taste of a particular food and the onset of an illness, but not between sights and sounds and an illness.
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Biological Predispositions
Taste aversion in rats (Garcia & Koelling, 1966): Rats are biologically prepared to learn associations between the taste of a particular food and the onset of an illness, but not between sights and sounds and an illness.
1-­‐‑
Violation of the notion that for conditioning to occur, US must immediately follow the CS.
2-­‐‑ Violation of the notion that any perceivable stimulus can serve as CS.
Taste aversion supports Darwin’s principle of natural selection – those who avoid toxic food will be more likely to survive and reproduce.
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Biological Predispositions
Biological preparedness also explain why we humans seem to be predisposed to learn associations between the color red and women’s sexuality (Elliot & Niesta, 2008).
e.g., Female primates display reddened genital regions when when nearing ovulation. Women have enhanced blood flow to the skin, are more likely to blush, and expose the skin during this time.
Thus, the frequent pairing of red and sex (e.g., Valentine’s Day candy, red-­‐‑
light districts, red lip stick, red lingerie) is found to enhance men’s acraction to women).
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Biological Predispositions
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Biological Predispositions
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Biological Predispositions
“Men who viewed a woman in a red shirt perceived her to be more attractive,
were more sexually attracted to her, and indicated a greater likelihood of
asking her on a date and spending money on a date with her.”
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Pavlov’s Legacy
•  Many responses other than salivation to
many other stimuli can be classically
conditioned in many other organisms
ranging from sea slugs to earthworms to
rats to dogs to monkeys to humans.
•  Through classical conditioning virtually all
organisms learn to adapt to their
environment.
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Pavlov’s Legacy
•  Pavlov has also shown how a process
such as learning can be studied
objectively across many organisms.
•  e.g., amount of salivation, freezing
response, nosepoke
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Applications of Classical Conditioning
Nausea Conditioning in Cancer Patients
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Applications of Classical Conditioning
Classical Conditioning of Emotions
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Applications of Classical Conditioning
•  Former drug abusers often feel a craving when they
are again in the drug-using context – with people
and in places they associate with previous highs 
thus, they are advised to stay away from people and
setting that may trigger these cravings (Siegel,
2005).
•  E.g., Former crack cocaine users should avoid cues
(people, places) associated with previous drug use.
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Applications of Classical Conditioning
•  Classical conditioning even works on the immune
system  when a particular taste accompanies a
drug that influences immune responses, the taste
eventually by itself may produce an immune
response (Ader & Cohen, 1985)
•  Clinical psychologists use extinction procedure or
even new conditioning to help people change
unwanted responses to emotion-arousing stimuli
(e.g., fear of elevators, phobias).
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Watson’s Licle Albert
•  John B. Watson argued that human behavior is a collection of conditioned responses. •  He found that a loud sound is a potent unconditioned stimuli for fear and demonstrated that fear can be conditioned in infants.
•  He conditioned an 11-­‐‑month-­‐‑old baby named Albert to fear laboratory rats by making a loud sound when Albert was paying acention to the rat.
•  Albert was playing happily with the rat, then he was exposed to 6 stimulations with a loud sound.
•  After Albert was conditioned to fear the rat, he exhibited generalization by crying at the sight of other furry creatures including a rabbit.
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Watson’s Licle Albert
Demo
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