Transcript Chapter 5: Learning

Classical Conditioning
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Pavlov’s experiment - psychic
secretions.
Pavlov was a Russian physiologists who
studied digestion.
He won the Nobel prize in physiology in
1904 for his work on the digestive
system in dogs.
Classical Conditioning
Psychic Secretions.
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Some of Pavlov’s work with his dogs
involved placing objects on the dog’s
tongue and measuring the amount of
saliva produced.
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Sand more than marbles
amnt’s of food.
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He noticed that some of his dogs began to
salivate before food powder was put on their
tongues.
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Psychic secretions.
Similar to your pet getting excited at the sight of
you picking up it’s food bowl.
He found that stimuli associated with food
produced similar amounts of saliva as did
actual food
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Pavlov recognized that this salivation to
stimuli associated with food was just as
reflexive (out of the animals control) as
was food on the tongue.
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The conditioned reflex.
Pavlov set about trying to understand how
conditioned reflexes occur.
The Unconditioned Response
(UCR)
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This is a reflexive response to certain
stimuli that animals are born with
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Food = salivation
tapping knee = knee Jerk
puff of air on eye = eye blink
The Unconditioned Stimulus
(UCS)
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The stimulus that causes an
unconditioned response is the
unconditioned stimulus. It is a stimulus
animals are born to respond to.
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Food = salivation
tapping knee = knee Jerk
puff of air on eye = eye blink
The Conditioned Stimulus
(CS).
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The conditioned stimulus is some
stimulus that the experimenter presents
that predicts an unconditioned stimulus.
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Pavlov paired the sound of a bell (CS) with
placement of food (UCS) in a dog’s mouth.
If you sound a bell and then immediately
put food in a dog’s mouth what happens?
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It salivates (UCR).
The conditioned response
(CR).
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If you sound a bell (CS) and
immediately place food (UCS) in a dogs
mouth, several times, what will happen
if you just ring the bell?
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Test = Bell (CS) alone = salivation
Salivating to the bell in the absence of food
powder is called a conditioned response
(CR).
This reflects learning.
Summary of Classical
Conditioning
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CS -->UCS = UCR
bell -->food = salivation
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do this several times and then test with the CS
alone
CS = CR
bell = salivation
Twitmeyer’s patellar
conditioning
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Twitmeyer was examining the human knee
jerk reflex at the same time Pavlov was
studying salivation in dogs.
UCS - hammer on knee
UCR - Knee Jerk
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He had a bell (CS) that sounded when the
hammer’s fell.
One day he accidentally rang the bell without
dropping the hammer (What happened)?
Classical conditioning
phenomena
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Acquisition
Extinction
Spontaneous recovery
Stimulus Generalization
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train with one tone test with others
Discrimination
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One tone means food, one does not.
Instrumental Conditioning
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Thorndike
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Chicks and Mazes
Cats and puzzle boxes
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Were there signs of reasoning abilities?
The law of effect
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A response followed by a pleasant
consequence will become more likely
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Satisfying state of affairs
A response followed by an unpleasant
consequence will become less likely
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Dissatisfying state of affairs
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Reinforcement - an event that increases
the future probability of the most recent
response. RF stamps in a response
Punishment – an event that decreases
the future probability of the most recent
response. Punishment stamps out a
response.
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Very mechanistic
Skinner and the operant
chamber (Skinner box).
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Rats get levers
Pigeons get keys
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Now you had an easily quantifiable response.
Operant conditioning
(Instrumental conditioning)
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The process of changing behavior by
following a response (operant) with
reinforcement.
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What’s the difference between operant and
classical conditioning?
Operant vs. Classical
Conditioning
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In operant conditioning the subject’s behavior
determines an outcome and is affected by that
outcome.
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Response – stimulus  change in behavior
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Touch stove – get burned  less likely to touch the stove
In classical conditioning, the subjects learn that two
stimuli go together. Usually that some stimulus (sight
or sound) that is paired with something the organism
likes (food) or dislikes (pain).
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Stimulus – Stimulus  change in behavior
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See Stove – get burned  fear stove
Reinforcement vs Punishment
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Skinner defined these terms by their
outcomes.
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Anything that increases the likelihood of a
response is a reinforcer
Anything that decreases the likelihood of a
response is a punisher.
Is food a reinforcer?
Reinforcement
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Positive reinforcement
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Negative reinforcement
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Both increase behavior
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but for positive Reinforcement something good
happens.
for negative Reinforcement something bad is
taken away.
Punishment
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Positive punishment
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Negative punishment
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Both serve to decrease behaviors
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positive punishment involves giving something to you for
your behavior (something bad)
whereas negative punishment involves taking something
away (something good).
Try these
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Rat stops pressing a bar because each time
he does he gets shocked
Rat presses a bar to stop shock from
occurring
Rat presses a bar because each time he does
he gets food
Rat stops pressing a bar because pressing the
bar causes food to be delayed from when it
would normally occur