L2 - The Hull-Spence Model Flashcards
Learn about the Hull-Spence Model
What is the benefit of using a mathematical model?
It can make accurate predictions.
What is this formula?
ΔVA(t) = k(λ - V(t-1))
The Hull-Spence Model
What does surprise have to do with learning?
If an animal is surprised by something, it generates large changes in associations and has increased learning.
What does ‘V’ represent in the Hull-Spence Model
The change in the strength of the CS(A)-US association on trial (t).
What does ‘A’ represent on the Hull-Spence Model?
The conditioned stimulus (e.g. bell)
What does ‘Δ’ (delta) represent in the Hull-Spence Model?
In maths, delta means a change. ΔV will always mean the change in the strength of the association.
What does ‘(t)’ stand for in the Hull-Spence Model?
It stands for the current trial we are having.
What does λ (Lambda) represent in the Hull-Spence Model?
How strong the unconditioned stimulus was.
Actual Outcome (relative):
λ = 1 if US is present
λ = 0 if US is absent.
What does VA(t-1) in the Hull-Spence Model represent?
Expected Outcome = Associative strength that A has acquired up until trial t.
In the Hull-Spence Model, what does λ - VA(t-1) represent?
The extent to which the US wasn’t expected.
Surprise!
What does the k( ) around the λ - VA(t-1) represent?
k(λ - VA(t-1))
It is the learning rate parameter
(Speed of Learning)
In the first trial with an animal, what would you expect the VA value be?
Why?
It should be at 0.
For the animal has never seen the US before and therefore there is maximum surprise.
Using the Hull-Spence Model, if the amount of learning from an animal at the end of your first trial is 2 what would you change in your formula for the second trial?
You would change the Δ (delta) to 0.2 (VA(2))
What does asymptote mean?
A straight line that continually approaches a given curve but does not meet it at any finite distance.
A line that a curve approaches, as it heads towards infinity.
What does negatively accelerated mean?
It means that the rate (of learning) is slowing down.
In learning, what does extinction mean?
It means to unlearn a learned behaviour.
If your Hull-Space Model equation gives you a negative result what does that mean?
It means that you are surprised by the omission of something.
The associative strength will go down, the beginning of extinction if paired with the US.
What is the problem with the Hull-Spence Model? What assumption does it make that is wrong?
It assumes that learning about one CS is independent from learning about other co-occurring CSs when it is not.
i.e., it doesn’t matter if other CSs are also present.
What is the blocking effect?
If you train an animal to pair 2 CS (A+B) together with a US the they will have a strong CR, but if you have a phase beforehand where you only pair one stimulus (A) and in the second phase pair A+B with US B will have a weak CR.
It’s as if A is blocking learning about B, this is called blocking.
