Transcript Document

Factors Influencing Conditioning
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
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CS and US Intensity, and Attention to the CS
Temporal relationship
Predictiveness
Preparedness
Redundancy
CS Intensity Affects Rate
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Strong CS
CS
US
Weak CS
cs
US
Suppression and CS Intensity
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Another CS Intensity Effect
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Overshadowing – the more salient CS wins if
two CS are trained in compound
Group
Overshadow
Control
Stage 1
Ax  US
ax US
Note: Undercase letters stand for weak intensity CSs
Test
cr
CR
CS Attention and Latent Inhibition
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Group
Phase 1
Experimental X,X,X…
Control
---
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Phase 2
XUS
XUS
Test
cr
CR
Because the CS is a benign stimulus it will lose the capacity to
command ATTENTION if preexposed
Little “x” will eventually produce a robust CR
The Influence of Intensity
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
Exception: The effect of the CS on the intensity of
the CR is sometimes seen when the subject is
exposed to both the high and the low intensity CSs
which are individually paired with the US on
separate trials.
US Intensity Affects Rate and Asymptote
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Strong US
CS
US
Weak US
CS
us
Suppression and US Intensity
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Temporal Relationship
Weaker conditioned responding
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CS
Delay
US
Trace
CS
US
Simultaneous
CS
US
Explicitly
Unpaired
CS
US
Time Conditioning
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No distinctive CS
UCS is presented at regular intervals
The passage of time is CS
To determine whether conditioning has occurred, the
UCS is omitted and the strength of the CR is
assessed
Indirect Conditioning
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
Many stimuli develop the ability to elicit a CR
“indirectly”
 i.e.,
a stimulus that is never itself paired with a UCS
comes to elicit the CR

Two important ways for this to happen are
 Higher-order
conditioning
 Sensory preconditioning
Higher-Order Conditioning
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Group
HOC
Control
Stage 1
AUS
CUS
Stage 2
BA
BA
Test
B?
B?
Result
cr
ziltch
HOC: A modest CR develops to B because if signals a
“reminder” for the US, namely, the already conditioned A.
Sensory Preconditioning
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Group
SPC
Control
Stage 1
BA
BA
Stage 2
AUS
CUS
Test
B?
B?
Result
cr
ziltch
SPC: A modest CR occurs to B at test, because it signals the
A, which is now a “reminder” for the US.
CS-US Preparedness
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From Garcia & Koelling, 1966
Back
Predictiveness of the CS
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Are forward pairings enough to
generate a CR? No!!!!!!!!
Predictiveness of the CS
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Predictiveness: the consistency with which the CS is
experienced with the UCS, which influences the
strength of conditioning.
The pairing of a CS and UCS does not
automatically ensure that conditioning will occur.
A Contingency Experiment
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CS
US
Chance of US per CS = 2/4 = .5
Chance of US outside CS = 0/10 = 0
Positively
Correlated
A Contingency Experiment
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CS
US
Chance of US per CS = 2/4 = .5
Chance of US outside CS = 5/10 = .5
Uncorrelated
A Contingency Experiment
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CS
US
Chance of US per CS = 0/4
2/4 = .0
.5
Chance of US outside CS = 5/10 = .5
Negatively
Correlated
It’s a little like…
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Animals are scientists, trying to make cause->effect
predictions.
…trying to determine whether the US is contingent
on the CS
…lots of pairings in the zero contingency group
Quantifying
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p(US|CS) = proportion of CS trials with a US
p(US|no CS) = proportion of “background” only
trials with a US
Dp = p(US|CS) - p(US|no CS)
Some Examples
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p(US|CS)
p(US|no CS)
Dp
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20/20 = 1.0
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0/60 = 0
• 1.0
1
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15/20 = .75
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6/60 = .10
• .65
2
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10/20 = .50
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30/60 = .5
• 0
3
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10/20 = .50
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45/60 = .75
• -.25
4
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0/20 = 0
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60/60 = 1.0
• -1.0
5
1.0 1
Positive
P(US/ CS)
2
+1.0
+.65
-.25
3
4
-1.0
Negative
0
P(US/no CS)
5
1.0
Redundancy
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Group
Blocking
Control
Stage 1
AUS
Stage 2
ABUS
ABUS
Test
B?
B?
Result
cr
CR
Blocking: Limited or no acquisition of a CR to a second
conditioned stimulus, B, when it is introduced alongside an
already conditioned first conditioned stimulus , A.
Extinction Paradigm
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Extinction of a conditioned response: when the
conditioned stimulus does not elicit the conditioned
response because the unconditioned stimulus no
longer follows the conditioned stimulus
Loss of the CRs
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Hull considered the extinction process to be a mirror
image of the acquisition.
 It
is not. One reason for faster extinction than
acquisition is that extinction alters the motivation level
via omission of the UCS.
 Decline is also caused by the development of inhibition
rather than erasing the first-learned CS-US association.
 So, the CS is part “excitatory” and part “inhibitory”
after the end of the last extinction trial
Evidence for new learning
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A rest period after the last extinction trial can
produce spontaneous recovery. More rest causes
more spontaneous recovery.
If extinction takes place in a different context than
acquisition, a return to the original context of
acquisition causes the immediate return of the CR
(called ABA renewal).
Duration of CS Exposure
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
As the duration of CS-alone exposure increases, the
strength of the CR weakens
 Shipley
found total duration of CS alone exposure, not
number of extinction trials is critical, but subsequent
research has not always confirmed his result.
Exposure Therapy
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To increase sustained abstinence, some therapists
have used a technique that involves exposing the
addict to as many drug related cues as possible
during extinction.
Withdrawal responses and drug cravings decrease
as a result of exposure to drug-related cues.
Systematic Desensitization
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Developed by Joseph Wolpe
Used to inhibit fear and suppress phobic behavior
SD uses counterconditioning and Wolpe based it on
three lines of evidence
Systematic desensitization
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Involves performing deep muscle relaxation
techniques while first imagining, and then
experiencing, anxiety-inducing scenes
 Relaxation
involves cue-controlled relaxation, a
conditioned relaxation response that enables a word
cue (e.g., “calm”) to elicit relaxation promptly
Stages
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
Systematic desensitization consists of four separate
stages:
 1)
construction of the anxiety hierarchy
 2) relaxation training
 3) counterconditioning – the pairing of relaxation with
the feared stimulus and exposure therapy
 4) assessment of whether the patient can successfully
interact with the phobic object
Hierarchies
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Hierarchies may be either
 Thematic:
scenes all related to a basic theme
 Spatial-temporal: based on phobic behavior in which
the intensity of the fear is determined by distance –
either physical or temporal