L3 - Rescorla-Wagner Model Flashcards
Once an animal has fully learned a CR, the first time it experiences the CS without the US will it have a large extinction effect or a small extinction effect on the CR?
Why?
It will have a large extinction effect.
This is because the animal is very surprised that what it was expecting didn’t happen. The more the US is shown without the CS the more extinction will happen but a decreasing acceleration rate.
How is the Rescorla-Wagner Model different to the Hull-Spence Model?
They changed the expected outcome formula to be the sum of the associative strengths of ALL CSs present on the trial t.
ΔVA(t) = k(λ - ΣV(t-1))
What is the name for Σ?
Sigma
Why was the Rescorla-Wagner Model change from the Hull-Spence Model necessary?
Because the Hull-Spence Model didn’t account for the change in learning speed due to phenomena such as blocking due to multiple stimuli (inhibitors) being present.
If you have already conditioned ‘A’ with the US then try to teach ‘B’ while presenting ‘A’ at the same time, what effect will this have on learning speed and why?
The animal has already learned to associate A with the US so the presence of B doesn’t change anything and is therefore unsurprising so there will be slow learning.
This is called blocking.
What is Selective Learning?
The phenomenon that animals only seem to learn associations about things that are not redundant.
It is harder to learn things that are not novel or relevant.
What is a Redundant Stimulus?
One which provides no new information.
If we already associate A with the US, pairing B with A will not prolificate learning of the association of US with B. This is because A gives us all the information we need.
What is an Excitor?
A stimulus that provokes a positive reaction and increases associative strength.
What is ‘Inhibition’?
Learning that a CS signals the absence of a US
What reaction will an animal have if you pair an inhibitor (CS) with a positive US (one it desires)?
What about a negative US?
The animal will be upset by the CS because it will not be receiving what it desires?
If the inhibitor CS is paired with the negative US it will have a positive response to not receiving the negative US.
What is Conditioned Inhibition?
It is a CS that the animal has learned will prevent the production of a US.
What is the Summation Test?
Test for inhibition.
What is the Retardation Test?
The second test for Inhibition.
Learning with B should be ‘retarded’ (learning more slow) than D
This signals the absence of B in the animal’s mind.
What should λ (Lambda) be if there is no US?
λ = 0 if no US
If two stimulus have a strong associative strength and then one stimulus is presented without the other, what will happen to the associative strength?
If it is unexpected there will be surprise and therefore the associative strength will decrease.
What happens to ‘B’ if AB (but only A is conditioned) are presented without US the animal has been conditioned to expect with A?
B starts to develop inhibition because it starts at 0 and therefore goes into the negatives.
When will associative strength stop when decreasing with an inhibitor?
VA will not go below .5 and VB not below -.5 as the two stimuli cancel each other out.
B protects A from full extinction.
Summarise the difference between the Hull-Spence Model and the Rescorla-Wagner Model.
