Download Classical Conditioning

Modules 18-19-20 Learning
Classical Conditioning
Operant Conditioning
Learning by Observation
Vocabulary
™Stimulus (Plural: Stimuli): an agent (as an
environmental change) that directly influences
the activity of a living organism or one of its
parts
™Response: The behavior or cognitive process
that occurs in reaction to a stimulus
Definition of learning
ƒ
Learning is a relatively permanent change in
behavior, or behavior potential, that occurs as
the result of practice or experience.
ƒ
Produced by experience: not changes that result from
maturation (neuromuscular development).
ƒ
Learning often takes place without immediately being
shown in behavior and the learned behavior may be
performed when there is an incentive to perform the
behavior.
Learning
™Unlike most animals, we do not have a genetic
blueprint for life.
ƒ E.g., migrating birds know where they are supposed
to go and how to go
™Much of what we do we learn from experience.
ƒ Learning is our way of adapting to our environment
We learn by association
ƒ We (and virtually all organisms) naturally
connect events that occur in sequence
ƒ Associative Learning: learning that two events occur
together
ƒ two stimuli
ƒ a response and its consequences
ƒ Conditioning
ƒ is the process of learning associations.
Learning
1.
Classical (or Pavlovian) conditioning
•
•
•
2.
Associate two stimuli
E.g. lightning and thunder
E.g. mosquito buzz and itching
Operant conditioning
•
3.
Associate a response and its consequence: repeat acts
followed by rewards and avoid acts followed by punishments
Observational learning
•
We learn from others’ experiences and examples (e.g., a child
modeling his father dealing with frustration)
•
Æ In all these ways of learning, we adapt to our environments.
Module 18: Classical Conditioning
A basic form of learning associations
Behaviorism (Watson)
™An approach to psychology that emphasizes:
ƒ That psychology should be an objective science.
ƒ That psychology should concern itself ONLY with
studying observable behaviors.
ƒ That psychology should not be concerned with
studying mental processes.
™A lot of what we know about learning was first
studied by behaviorists.
Classical Conditioning
™Ivan Pavlov
ƒ Russian physiologist
ƒ Nobel prize winner
ƒ Conditioning was just an accident: dogs salivating
before food was given
Classical Conditioning
ƒ Pavlov’s device
for recording
salivation
Pavlov’s Classic Experiment
Classical Conditioning:
Terminology
ƒ Unconditioned Stimulus (US or UCS)
ƒ stimulus that unconditionally--automatically and
naturally--triggers a response
ƒ Unconditioned Response (UR or UCR)
ƒ Non-learned, naturally occurring response to the
unconditioned stimulus
ƒ salivation when food is present
Classical Conditioning:
Terminology
ƒ Conditioned Stimulus (CS)
ƒ originally irrelevant (neutral) stimulus that, after
association with an unconditioned stimulus, comes to
trigger a specific conditioned response
ƒ Conditioned Response (CR)
ƒ learned response to a previously neutral conditioned
stimulus (e.g., salivating to tone after learning)
Classical Conditioning
ƒ Organism associates two stimuli
ƒ A neutral stimulus that signals an
unconditioned stimulus begins to
produce a response that is reserved
for the unconditioned stimulus
Conditioning Process
Conditioning Process
Conditioning Process
e!
Not
is
Conditioning Process
e th
Not
e!
Not
And
to o !
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 guy wrote his
thesis on this, and graduated.
Processes of Conditioning
ƒ
ƒ
ƒ
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Acquisition
Extinction
Spontaneous Recovery
Stimulus Generalization/ Discrimination
Acquisition
ƒ the initial stage in classical conditioning
ƒ the phase associating a neutral stimulus with an
US so that the neutral stimulus comes to elicit a
conditioned response
Timing of CS before UCS
Extinction
ƒ diminishing of a CR
ƒ in classical
conditioning, when a
US does not follow a
CS
ƒ E.g., ring the bell but do
not present the food Æ
less and less salivation
ƒ when done repeatedly, The
learned association will
become weaker and
weaker...
Spontaneous recovery
ƒ Reappearance, after a rest period, of an
extinguished CR
Classical Conditioning
ƒ Generalization
ƒ tendency for stimuli similar to CS to elicit similar
responses
ƒ Can be adaptive- as children taught to fear moving cars on
street to respond similarly to trucks and motorcycles on the
street
ƒ Discrimination
ƒ in classical conditioning, the learned ability to
distinguish between a CS and other stimuli that do
not signal a US
ƒ E.g., fear pitbulls but not golden retrievers
ƒ Lightning but not flashing disco lights
Updating Pavlov’s understanding
ƒ Role of mental processes
ƒ Thought/expectation of the CS-US link matters for
conditioning
ƒ Consistent link between the CS and US matters
ƒ Role of biological dispositions
ƒ Each species’ biological dispositions prepare it to
learn the associations that enhance its survival
ƒ Taste aversion (rather than sight) in rats - they 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.
Conditioned Taste Aversion
ƒ If a flavor is followed by an illness experience, animals
will avoid the flavor in the future
CS
Taste
+
CS ----->
Taste
UCS ----------> UCR
Toxic event
Nausea
CR
Nausea
ƒ Any real life applications?
ƒ Quitting smoking
Nausea Conditioning in
Patients
US
(drug)
CS
(waiting
room)
CS
(waiting
room)
UR
(nausea)
US
(drug)
UR
(nausea)
CR
(nausea)
Classical Conditioning: Key
Points
ƒ Can explain a wide range of behavior
ƒ Advertising, food aversion, phobias
ƒ Focuses on naturally occurring behavior
ƒ Any naturally occurring behavior (or response) can be
conditioned to neutral stimulus
ƒ Eye blink— bell
ƒ Sexual arousal—strawberries