Extinction
Session 1
Extinction
Session 2
Session 3
Theories of Extinction
• Forgetting?
• Associative loss? (= “reverse acquisition”)
Session 1
Extinction
Session 2
Session 3
Spontaneous recovery occurs as a function of time
Robbins (1990)
Extinction  Associative Loss
“Renewal”
Train
Tone  Shock
Extinguish
Test
Tone -
Tone: CR
Tone -
Tone: CR
Context A
Context B
Bouton & King (1983)
In contrast, acquisition is not context-specific
Train
Tone  Shock
Test
Tone: CR
Tone: CR
Context A
Context B
Extinction  Associative Loss
“Reinstatement”
Train
Extinguish
Reinstatement
Shock alone
ToneShock
Test
Tone: CR
Tone --
Tone: CR
So, what is learned in extinction?
Hypothesis: Extinction makes the S (CS or SD)an inhibitor
Before
Extinction
CS
US
After
Extinction
CS
No US
Inhibitory SR Associations Theory
• In extinction, the context effectively
becomes a conditioned inhibitor.
• Why? Just like in normal CI, there is the
violation of expectations of reinforcement
• But is this true?
Is cue A a conditioned inhibitor?
Here’s how to find out:
• Summation test:
• Retardation test:
Inhibitory SR Associations
Does extinction make the CS an inhibitor?
• Summation test
Train
Ext
Test
A+/B+
A-
Test: AB
Does A
inhibit
responding
to B?
• Retardation test
Train
Ext
Train
A+
A-
A+
Does extinction
inhibit
reacquisition?
So, what is learned in extinction?
An inhibitory SR association?
Context
S
R
Paradoxical Effects of Reward
• Overtraining extinction effect: more training
leads to faster extinction
• Reinforcement magnitude effect: Big
rewards lead to faster extinction
• And, of course, the partial reinforcement
extinction effect (PREE)
PREE: Why?
• Discrimination hypothesis: Nonreinforcement is
easier to detect after CRF than PRF.
A Test of the Discrimination
Hypothesis
CRF  CRF  EXT
vs.
PRF  CRF  EXT
X
PREE: Why?
• Discrimination hypothesis: Nonreinforcement is
easier to detect after CRF than PRF.
• Frustration hypothesis (Amsel): animals learn to
make response as a reaction to nonreward.
• Sequential theory (Capaldi): The memory of
nonreinforcement becomes a cue that elicits
responding.
• Expecation-based theories: speed of extinction
depends on violated expectations of
reinforcement.