Transcript Classical conditioning

Classical conditioning
Reminder of basic effect
What makes for effective conditioning?
How does Classical conditioning work?
Basic effect
If Unconditioned Stimulus  Unconditioned Response
(meat powder)
(salivation)
then pair
Conditioned stimulus with the unconditioned stimulus
(bell)
(meat powder)
then eventually
Conditioned stimulus  conditioned response
(bell)
(~salivation)
Who didn’t know this already?
Why is
Pavlov
famous?
Who didn’t know this already?
“Acts of recollection, as they occur
in experience, are due to the fact
that one movement has by nature
another that succeeds it in regular
order”
--Aristotle
Who didn’t know this already?
Are there foods that make you salivate?
Who didn’t know this?
If Unconditioned Stimulus--> Unconditioned Response
(sour taste)
(face)
then pair
Conditioned stimulus with the unconditioned stimulus
(sight of pickle)
(sour taste)
then eventually
Conditioned stimulus--> conditioned response
(sight of pickle)
(~face)
Measurement
• You can’t answer questions effectively without
an experimental method
• It’s not enough to say “she makes a face”
• How many times must she eat pickles?
• What if sometimes I offer a pickle-shaped candy?
• Can any stimulus be associated with any response?
• WHY does she make the face?
-Here comes that stupid food
-Associates sight of pickle with sourness
-Associates sight of pickle with face
Lots of questions you could ask
• What makes an effective CS and
US?
• How might classical conditioning
work?
• Belongingness
• E.g., Taste  barfing, sight  shock
CS
CR
CS
CR
CS
CR
CS
CR
NOTE THIS WAS ACTUALLY DONE WITH RATS
Belongingness is observed in humans, too. Fear conditioning
to snakes/spiders vs. flowers/mushrooms (dv = GSR)
What makes effective CS & US
• Novelty of CS or US
• Bell alone, then bellfood
– Bell associated w/ background
– Bell associated w/ no food
• Food alone, then bell  food
How does CC work?
Importance of one stimulus being
conditional on another.
How does CC work?
• Learning that one stimulus is conditional on
the other means that you’re learning about
the environment (food always follows bell)
• This implies that if one stimulus is not
conditional on the other, you won’t get
learning.
• Prediction 1: If you present CS and US
randomly, you shouldn’t get learning.
• Prediction 2: Animals should ignore stimuli
that don’t have predictive value.
Predictive value--blocking
Training 1
Group 1:
Group 2:
Light  food
x
Training 2
Test
Light  food
Tone
Tone  food
Light  food
Tone
Tone  food
Learning = bad
Learning = good
The point of blocking
The animal only learns what tone
means if tone carries
predictive information, even if tone
predicts food.
Rescorla Wagner Model
DVA=F(l-VA )
Where A= a particular US
VA=Associative strength
l = a threshold of activation
In blocking, asymptote for learning (l) has been
Reached during initial training, so further training  no learning.
l increases as the intensity of the US increases
Recorla-Wagner
The power of the Rescorla-Wagner model
is that it allows new predictions, some of
them unintuitive.
E.g., in blocking, you get no learning, despite
repeated pairings. It’s also possible to lose
associative strength despite repeated pairings.
Lose associative strength
Training
Test
Arbitrary units
Light->food
Tone->food
Light & tone->food
140
120
100
80
Test
60
40
20
0
1st ten
trials
2nd
3rd
4th
What does the learning look like?
• S-R theory
• S-S theory
Stimulus substitution theory (S-R)
US
UR
CR
Association
CS
But this doesn’t account for higher-order conditioning. . .
Higher-order conditioning
light  food
then
bell  light
Answer
The dog will salivate to bell.
S-S theory (rather than S-R)
Environment
US
Internal
representation
US
Response
Association
CS
CS
UR
CR
Which is right?
Early views favored S-R learning, and
viewed the organism in Classical
conditioning as passive.
More recent views favor the S-S view, in
which the organism seeks out
information about the environment.
Rigor allows prediction
Note how different this enterprise is
than my casual observation of my
daughter.
Application to humans?
Application to humans?
•
•
•
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Food aversions
Bed wetting
Advertising
Drug tolerance & addiction
Bedwetting
Wet Call Bedwetting Alarm/Pad
Wet Call is a moisture sensing bed
pad/alarm specifically designed for
habitual bed wetters… The Wet Call
bed pad is placed under the child
and the alarm sounds when the
pad’s sensor strips detect moisture.
http://www.bedwettingstore.com/bedwetting-wetcall.htm
If Unconditioned Stimulus Unconditioned Response
(alarm)
(waking)
then pair
Conditioned stimulus with the unconditioned stimulus
(full bladder)
(alarm)
then eventually
Conditioned stimulus conditioned response
(full bladder)
(~waking)
If Unconditioned Stimulus--> Unconditioned Response
(sight of babe)
(positive evaluation)
then pair
Conditioned stimulus with the unconditioned stimulus
(sight of cigarettes)
(sight of babe)
then eventually
Conditioned stimulus conditioned response
(sight of cigarettes) (~positive evaluation)
Opponent process model of drug
tolerance
Initially, the drug causes
a big response, e.g., hypothermia
The body struggles to get back
to homeostasis (raise body temp.)
Habituating to the drug means
those processes (hyperthermia)
kick in before the drug acts.
Opponent process model of drug tolerance
If Unconditioned Stimulus Unconditioned Response
(opiate)
(hyperhermia)
then pair
Conditioned stimulus with the unconditioned stimulus
(sight of drug)
(opiate)
then eventually
Conditioned stimulus conditioned response
(sight of drug)
(~hyperthermia)
Are there really such opponent
processes?
Opiate Administration
Hypothermia
Decrease blood pressure
Peripheral vasodilation
Respiratory depression
Relaxation
Analgesia
Opiate Withdrawal
Hyperthermia
Increase blood pressure
Peripheral vasoconstriction
yawning, panting
restlessness
Pain sensitivity
Predictions:
Craving for drug is an attempt to get back to homeostasis:
Craving is caused by Conditioned stimuli
e.g.: being offered “taste”
seeing a friend shoot up
talking about drugs
being in locale where you used to shoot up
seeing “works”
Likelihood of overdose is higher in unfamiliar surrounding
Drug rehab. should take place in typical drug-using setting