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Updated: Monday, April 12, 1999 10:50:10 AM
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Section 2:
Classical
Conditioning
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Important
Abbreviations
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| CS |
Conditioned Stimulus |
CR |
Conditioned
Response |
| UCS |
UnConditioned Stimulus
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UCR |
Unconditioned Response |
| NS |
Neutral
Stimulus |
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| Before
Conditioning |
| Bell (NS) |
à |
No
salivation response |
| Food was
presented (US) |
à |
Naturally
the animal salivates. (UCS) |
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| After
Conditioning |
| Bell (CS) |
à |
Salivation
response (CR) |
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| Pavlov – Russian
physiologist who investigated classical conditioning |
| Pavlov
received the Nobel prize for studying digestion:
He put windows into the digestive tract of dogs
and watched portions of the digestion process.
He also studied salivation, which is part
of digestion. When he fed the animals, he
measured saliva, which was an unconditioned response. |
He found that the dogs would sometimes begin
salivating when he would open the door.
The dogs were apparently salivating in accordance
to sounds that were associated with the food.
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Pavlov decided to study conditioning, which
is the most basic form of learning. - If you
ring a bell just before you feed an animal
for several trials, eventually the bell will
elicit salivation.
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| Example
of Classical
Conditioning: (Take
careful note of the
terminology used) |
Bell (CS) is associated to meat powder
(UCS) à
Salivation
N = Number of Trials
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First taught, then do an extinction trial, then wait,
until it is extinguished, then wait a day with out any
trials, the spontaneous recovery of the Acquisition
(or the reappearance of the conditioned stimulus) is
smaller than the original response.
SIMPLY STATED:
FIRST: (acquisition) A dog is first taught
that the bell promises food and will salivate when
the bell is rung, even before food is presented
SECOND: (Extinction) Now the scientist tries
to extinguish the conditioned response so that the
the bell will not be associated with the food. To
do this the scientist rings the bell, but does not
present any food. After a few trials, the dog
finally realizes that the bell no longer promises
food, and therefore the dog stops salivating when
the bell rings.
Third: (Spontaneous Recovery) In some situations,
a previously extinguished conditioned response may
reappear after some time has passed. This is call
spontaneous recovery. After some time has passed,
the dog may again salivate when the bell rings without
further learning trials. Spontaneous recovery can
be prevented by over extinction: continuing the extinction
trials.
Legend:
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___ =
Stimulus off
--- = Stimulus on |
___---___ =
[off on off] the --- is
the duration of
"on"
Our example is:
CS = Bell
US = Opening the Drawer
containing Meat |
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| Paradigm |
Time |
| Simultaneous
Conditioning. |
CS
____---____ - ring bell and open meat drawer
US ____---____ |
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Delayed conditioning
Strongest Conditioning.
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CS
_------------_
US ______-----_ |
| Trace
Conditioning |
CS __---______
US ______---__ |
| Temporal
Conditioning |
US __---__---__ |
| Backward
Conditioning |
CS ______---_
US ___---____ |
| Stimulus
Generalization |
If you condition a dog using
a bell that rings at 5000 cycles per second
and you use the same bell, you get the same
response.
But if you ring a bell that rings at 3000 cycles
per second you get a diminished salivary responses
in comparison to the bell which rings at 5000
cycles per second.
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To eliminate generalization and enhance discrimination:,
give the animal food over several trials when
the the 5,000c/s is rung; then ring bells
with frequencies close to 5000c/s but never
feed the dog, the dog will then lean to discriminate
between a 5000c/s bell and other bells.
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| John Watson
& his assistant Ms.
Rayner |
"Little Albert"
Experiment - The conditioned fear of
cute fuzzy animals.
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In the beginning little Albert
played freely with a white rat. But later,
Watson paired a loud noise with the presentation
of the rat. Albert became afraid of the
rat, and subsequently other small cute fuzzy
animals.
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Mary Cupboard Jones –
helped with behavioral psychology and the treatment
of phobias. Invented systematic desensitization
(a treatment for phobias).
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| Conditioned
Food Aversion – if you get sick after
eating something, there is a likelihood that you
will not choose to eat it again, that is, you will
avoid the food. |
This was used by shepherds who wanted to protect
their flock from coyotes.. They would put out
some tainted meat that made the coyotes sick.
The coyotes would then no longer want eat the
sheep.
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| Conditioned
Immune Response - The immune response can
be classically conditioned. - Example: if a drug
which lowers the immune system is paired over several
trials with a specific taste (saccharin) the animal's
immune system will be lowered by the taste alone.
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| Homeostasis
- the body strives to maintain a constant
biological state. |
| Conditioned
Compensatory Response(learned tolerance) |
If a rat is put in a cold dark
ice box, his body temperature drops.
After exposing the rat to this situation several
times, it will be conditioned.
If the ice box is no longer
cooled and the rest of the situation remains
the same, what will happen when the animal is
put in the box? Will the animal's body
temperature increase or will it decrease?
Paradoxically
the animal's body
temperature will increase!
The
rat's body will be
tricked into compensating
for the cold, even though
there is none - his body
temperature will therefor
rise. This is an example
conditioned compensatory
response.
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| Tolerance
– Decreased
effectiveness of a drug
through repeated
exposure. |
| Learned tolerance
– Conditioned tolerance. Is created
by a conditioned compensatory response. |
Example: Some drugs have similar
effects/problems… if a drug is taken the
body will remember the environment in which
the drug was taken, so if you usually take a
drug with friends your body begins to build
up a tolerance for the drug in the presence
of the conditioned stimulus - friends,
but later take it by your self, you have a higher
likelihood of overdosing because the conditioned
stimulus is absent, there is no conditioned
compensatory response lessening the effect of
the drug.
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