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Nature of the Conditioned
Response
Chapter 5
The Stimulus Substitution Theory
2


Originally suggested by Pavlov
Stimulus substitution theory
 Pairings
of the CS and the UCS enable the CS to later
elicit the US representation. So, the CS is treated as if it
were the US.
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But ………………
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
In many cases the CR and UCR are not the same
 Problem
1: In some cases the CR and UCR seem
opposite each other.
 Problem
2: And sometimes the CR changes over the
interstimulus interval.
Sometimes-Opponent Process Theory
5

Wagner’s SOP theory invokes the concept that the
UCS elicits two states of memory activity (two
components)
A
primary A1 memory (dealing with a present US)
 A secondary A2 memory (thinking about a future US)


CS always elicits A2 memory of the US
 A2 memory is sometimes linked to non-opponent
response (salivation)
 A2 memory is sometimes linked to an opponent
response (drug tolerance)
Problem 1 Solved
Affective Extension of SOP (AESOP)
6


Developed by Wagner and Brandon to explain the
inconsistencies that SOP could not explain
It is based on the idea that there are two distinct
UCR sequences
A
sensory sequence
 An emotive sequence
Fear (optimal ISI, long)
CS
Blink (optimal ISI, short)
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


The sensory and emotive attributes of an
unconditioned stimulus activate separate response
sequences
The latency of the sensory and emotive activity
sequences can also differ
This leads to different optimal CS-UCS intervals for
the emotive and sensory components
8

There are several important aspects of AESOP
A
CS may activate a strong sensory CR but only a
weak emotive CR (or vice versa)
 This
can explain the lack of correspondence between
response measures of conditioning
A
sensory A2 neural activity may elicit a discrete
response (blink), while the emotive A2 neural activity
may produce a diffuse reaction (fear)

Problem 2 Solved