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Classical Conditioning
Learning & Memory
Arlo Clark-Foos
What is classical conditioning?
• Learning to associate previously neutral
stimuli with the subsequent events.
• Howard Eichenbaum’s Thanksgiving
Pavlov’s
psychic secretion
Are you conditioned?
• Some examples of every day
conditioning…
– Holiday Traditions
– Food Associations
– Fears
– Superstitions
– Habits
– Skills?
Ivan Pavlov
• How are digestive fluids controlled?
– Historical view
– Pavlov’s view
– Pavlov’s Original Experiment
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Pavlov’s Experiments
• Psychic Secretion
– Specialized procedure for introducing food
• Claude Bernard’s psychic secretion in horses
– Pavlov’s psychic secretion was unreliable but…
Pavlov Museum, Ryazan, Russia
Stimuli and Responses
This is appetitive
conditioning. What is an
example of aversive
conditioning?
Conditioned Emotional Response
Estes & Skinner
(Dudai, Jan, Byers, Quinn, &
Benzer, 1976)(Domjan, Lyons, North, &
Bruell, 1986)
Appetitive
Slapping and Blinking in the Name of Research
Clark HullErnest Hilgard
Electromyography (EMG) Photo Sensors
Very well
studied
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Rabbit Eyeblink Conditioning
reactive
predictive
It gets more complicated…
• Similarity among species
• Tolerance, compensatory responses, and homeostasis
• Stimulus Timing and Presentation
– Contemporaneous Presentation
• Not spaced too far apart in time
– Is there an ideal spacing?
– Order and Consistency
• Reliable relationship/expectation
Conditioning Procedures
Forw
ard
Conditio
nin
g
Interstimulus
Interval
Intertrial
Interval
Learning Not to Respond
Conditioned Inhibition: Decrease in CR in
response to CS.
– Need Baseline
CS+1(Tone) US
CS-2(Light)
CS1 ?
CS2 ?
Baseline
CS1 + CS2
CRs diminish
over time as CS-
inhibits CS+
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Transfer of Learning
• Generalization
• Discrimination
CS(Tone,1200mHz) US
CS800mHz CR
CS1200mHz Max CR
CS1600mHz CR
CS(Tone,300mHz)
CS(Tone,500mHz) US
CS(Tone,800mHz)
CS300mHz
CS500mHz CR
CS800mHz
Context as CS
• Penick & Solomon (1991)
– Eyeblink conditioning in rats
– Hippocampal Lesions
Transfer Appropriate Processing
& Encoding Specificity
What is being conditioned?
• How is it learned and what is the nature of the
association?
S-S or S-R Association?
• Stimulus Substitution Theory (Pavlov)
– Definition (S-R Association)
– US, CS, and Response centers in the brain
– Problem: a CR is not a UR
• CR eyeblink is often more gradual and less complete
US
Response
CS S-R Association
S-S Association
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Rescorla (1973)
US Devaluation
Less CR after US devaluation.
S-S Association
Conditioned
Suppression
(Light/CS +
Loud Noise/US)
Lever RewardHabituate Noise
Lever + Light?
US
Response
CS S-R
Association
S-S
Association
After Conditioning
• After learning, what happens when you
present the CS alone?
Extinction
What happens in extinction?
• What do we (researchers) see?
– No CR = Forgetting?
– Excitatory and Inhibitory Associations (Pavlov)
• CC
• Extinction
Human eyeblink conditioning and the reduction in responses during extinction.
Extinction = Forgetting?
• Spontaneous Recovery
– Pavlov: Inhibitory connections are weak, fade
– Alt. Theory: Attention/Interest in CS (habituation?)
Human eyeblink conditioning and the reduction in responses during extinction.
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Extinction = Forgetting?
• Disinhibition
– Surprising, typically arousing, new stimulus
– Return of CR (akin to sensitization)
• Rapid Reacquisition
– Retraining vs. Original Conditioning
– Something is retained
Extinction is NOT Forgetting
Compound Conditioning
• Context, Multiple Cues
– Extinction: “respond” and “don’t respond”
• Overshadowing
– Salience
Error Correction
• Problems with Aristotle’s contiguity
• Informational value of cues
• Kamin’s (1969)
Compound
conditioning
Rescorla-Wagner (1972)
• Learning on Trains
– Contiguity is not enough
• Competition for associative strength
• Prediction Error
– Positive vs. Negative prediction errors
– Error-correction learning
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R-W in Humans
• Error Correction in Human Category Learning
– Bower & Trabasso, 1964
• Informational value of dot
Modelling Conditioning
• Associative Weights
– Connectionist Models (e.g., McClelland & Rumelhart)
Pay Attention!
• Exposure to CS alone retards later learning
– Attention to stimuli
– Latent inhibition
• Lubow & Moore (1959)
– Sheep and Goats
• Where is the surprise?
– US Modulation Theory
• Prediction error (Rescorla & Wagner, 1972)
– CS Modulation Theory
• Attention to stimuli (Mackintosh, 1975)
Properties of C Conditioning
• It takes time
– 4-5 mo., no eyeblink conditioning in
first block but exposure necessary for
later learning.
• Other Factors
– Intensity of CS-US
– Timing, ISI
Ivkovich et al., 1999
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Intensity of CS-US
• Faster and More effective
US Intensity
Decreased
US Intensity
Maintained
Timing, ISI
• Timing is critical!
– Ideal ISI for rapid learning
– Humans = AnimalsPavlov observed no CRs
with Backward
Conditioning: CS does not
predict US.
Animals must be learning
association AND temporal
contiguity
Taste Aversion (Garcia Effect)
• Temporal Contiguity
– Food poisoning after a date…
• Belongingness: CS-US pairings.
– Tone + Food Shock or Poison
– (Garcia & Koelling, 1966)
• Neurological basis: gustatory cortex
• Coyotes (Gustavson et al., 1974)
Neural Basis in Mammals
• Cerebellum
– Purkinje cells
• Inhibitory connection to
interpositus nucleus
– Interpositus nucleus
• CR output pathway
• Error correction
• Brain Stem
– Pontine nuclei (CS)
• Specialized sensory processing
– Inferior Olive (US)
• Activates interpositus nucleus and
Purkinje cells
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Neural Bases of CC
A simpler
diagram of
Rabbit
eyeblink
conditioning
Cerebellum
• Electrical activity
• Stimulating the inferior olive
– Even specific tones, lights, etc.
– Substitute for actual US
• CC impaired after damage
Purkinje cells
CS Modulation
• Latent inhibition not explained by RW
• Mackintosh (1975)
– Salience of Sensory cues
– Hippocampus
• Animals without do NOT
show latent inhibition
Back to Aplysia
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CC in Aplysia
1. Aplysia and Eric Kandel
Neural Bases of CC
In the long run,
it’s all just LTP
Proteins
• Two routes to long lasting memory
– Activate CREB-1
• Synaptic growth
– Deactivate CREB-2
• Rapid learning
Addiction and Tolerance
• Homeostasis and compensatory responses
– Environmental cues as CS
• Reducing reliance on drugs?
+ +
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