L11 - Extinction Flashcards
What happens when the CS is no longer paired with the US?
Extinction - the conditioned response (CR) stops
What does the R-W model assume the value of lambda is for non-reinforcement?
0
What happens according to the R-W model, when the CS is presented without the US?
It generates a -ve discrepancy (US is expected but absent)
Lambda = 0, sigmaV = 1 (0-1) = error term
When the CS is presented without the US, what happens to deltaV and V?
DeltaV is -ve and V begins to decrease
Why does lambda normally equal 1 in examples?
Due to convenience and ease of the model
How do you work out the true value of lambda when presented with a graph?
Find the asymptote
e.g. if asymptote = 17, then lambda = 17
We take the value of 1 in examples for convenience
Does the R-W model predict extinction?
Yes
Learning (V) decreases as CS-US pairing is extinguished
What is a partial reinforcement schedule?
The CS and the US are not always followed by each other - only partially reinforced
Under reinforcement schedule of 100% - every time CS is presented, followed by US
Under partial rft schedule of 50% - on 50% of time CS is presented, followed by US
Does the R-W model predict partial reinforcement schedules well?
Yes - the way it accounts for it is similar to extinction
Explain how the R-W model predicts partial reinforcement learning
R-W predicts a reduction in associative strength similar to extinction when the CS is not always followed by the US - this is because deltaV is -ve
Partial reinforcement schedules show a lower asymptote for learning
What does the R-W model predict for different learning schedules when they are being extinguished?
It predicts the highest asymptote takes the longest to decrease (i.e. continuous takes longer than partial because 100% is higher than 50%).
This is incorrect
What is the partial reinforcement effect?
Using a partial reinforcement schedule results in resistance to extinction - the R-W model does not account for this
How does the R-W model explain extinction and what are the 4 contradictions of this?
Explains it as unlearning the CS-US pairing, as if we are erasing the link
However, there are conditions that produce a recovery in responding following extinction:
Spontaneous recovery
Rapid reacquisition
Renewal
reinstatement of responding
What is spontaneous recovery?
Responding recovers to the CS simply by the passage of time
What is rapid reacquisition?
After extinction, conditioned responding to the CS is reacquired faster than before
Demonstrates that the CS-US link has not been completely erased
What is renewal?
After extinction of responding in one context, responding can be renewed if the CS is presented in a different context
What are the 3 different groups in the experiment that shows evidence for renewal?
Bouton and King (1983)
3 groups: All conditioned by a CS to a US
All learn in context A
First group: CS is extinguished in context A
Second group: CS is extinguished in context B
Control: not extinguished at all but is presented in context B
1-2 different in context
2-3 different in extinction
What are the results for the different groups in the renewal experiment?
After the initial conditioning suppression is high after the tone.
Gradually throughout extinction group A become less scared
Group B: RECOVERY OF FEAR IN CONTEXT WHERE IT WASN’T EXTINGUISHED
Control scared the whole time
What is reinstatement?
After extinction, responding can be reinstated if the US is presented alone
Reminder of the shock is enough to scare the CS
What is the explanation for extinction referring to “masking”?
Extinction is new learning about the CS that masks the original learning (but otherwise leaves it intact)
How does Bouton explain extinction?
Suggests animals acquire memories of the CS, not just a single memory but MULTIPLE
What is the key difference between Bouton’s explanation for extinction and the R-W model?
RW see it as single, Bouton sees it as different associations
After extinction, animals have 2 different memories with conflicting context
- memory of CS-US
- memory of CS alone (enters unambiguous state - remember second memory in that context)
What do animals use to decide which memory to retrieve (Bouton)?
They remember the second memory in that context.
The animals are using temporal and visual cues to decide which memory to retrieve
Are memories from extinction episodes situation specific according to Bouton?
Yes, they rely on the time and environment.
Under different context you will retrieve appropriate memory.
