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THEORIES OF CLASSICAL
CONDITIONING
Chapter 5
Rescorla-Wagner Explains
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1) Acquisition and extinction of a CS+
2) Acquisition but not extinction of a CS3) Overshadowing and blocking
4) Overexpectation
5) Supernormal conditioning
6) CS-US contingency
7) US preexposure
Contingency and the R-W model
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P(US/CS), pairing of CS with US
P(US/no CS), pairings of context with US
Cage
Experimental
Context
A day in the life of Sniffy the rat
Rethinking The Contingency
Experiment
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CS (A)
US
CONTEXT (X)
(AX+)
(X-)
Chance of US per CS = 4/5 = .8
Chance of US outside CS = 2/10 = .2
(X+)
(AX-)
DP = .6
P(US/CS)
P(US/no CS)
Perfect Positive
Contingency
DP = .8
DP = .6
DP = .4
Zero
DP = 0
Contingency
DP = −.4
DP = −.6
Perfect Negative
Contingency
DP = −.8
US Pre-exposure Effect
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US pre-exposure effect: Exposure to the US before
conditioning; it impairs later conditioning when a CS
is paired with that US.
 The R-W model: The presentation of the US
without the CS occurs in a specific environment or
context, which results in the development of some
associative strength to the context.
 Associative strength to the context reduces the
level of possible conditioning to the CS on the
early trials because VALL is nonzero.
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The US pre-exposure effect is attenuated when the
pre-exposure context is different from the
conditioning context
 Other contexts will not have strength, so
conditioning proceeds normally.
Rescorla-Wagner Doesn’t Explain
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1) Failure of a CS- to extinguish (a bad prediction)
2) Second-order conditioning (didn’t include but
known; lesson: CS to CS associations)
3) Latent inhibition or CS prexposure effect (didn’t
include but known; lesson: a should not be fixed)
4) Potentiation rather than overshadowing in taste
aversion
5) Performance effects, such as deflation
Potentiation of a Conditioned Response
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Rescorla-Wagner model predicts that when a
salient and nonsalient cue are presented together
with the US, the salient cue will accrue more
associative strength than the nonsalient cue
Overshadowing: In a compound conditioning situation,
the prevention of conditioning to one stimulus due to
the presence of a more salient or intense stimulus
Potentiation: Tastes often help (rather than hinder)
the development of odor aversions
Potentiation and Pregnancy Sickness
Later
Smell
Weak
Coffee Odor
Aversion
Smell
&
Taste
Strong
Coffee Odor
Aversion
Explanations of Potentiation of a
Conditioned Response
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Within-Compound Association (CS− CS
association): the association of two stimuli, one of
which is paired with a US, which leads both CSs to
elicit the CR.
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Configural Learning: Compound is treated as a
single unitary CS, and individual element for the
compound can each trigger the compound.
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Sensory-Gate Channeling: Taste opens a gate in
the brain allowing odor to serve as a CS for illness
when it otherwise would not.
Acquisition versus Performance
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Rescorla-Wagner attributes differences in CR
strength to learning. Responding to the CS is
determined by the associative strength of the CS on
the previous trial.
Comparator hypothesis argues that many
differences in CR strength are due to differences
performance. CR strength is determined by a
comparison of the associative strength of the target
CS and the associative other stimuli trained along
with the target (CSs or contexts).
Miller’s Comparator Hypothesis
Cue Deflation Effects
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Cue deflation effect: When the extinction of a
response to a comparator cue after
conditioning leads to an increased reaction to
the target CS.
 Rescorla-Wagner model cannot explain
change in the reaction if a CS if it has not been
presented in the interim
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Prototypical Cue Deflation Result
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Group
Exper
Control
Stage 1
A+ in Context X
A+ in Context X
Stage 2
XY-
Test A
CR
cr
When the extinction of a conditioning context
(Context X), but not a control context (Context Y),
after conditioning leads to an increased reaction
to the target CS (A)
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Mackintosh’s attentional theory proposes that the
relevance of and attention to a stimulus determine
whether that stimulus will become associated with the
US (related to the lesson that a should not be fixed)
Baker’s retrospective processing approach suggests
that conditioning involves the continuous monitoring of
contingencies between a CS and a UCS, with the
recognition of a lack of predictiveness diminishing the
value of the CS (related to comparator)