Lecture 10 - Rescorla-Wagner Model Flashcards
Is R-W the most successful and influential model of learning
YES
What does it mean when (lambda minus sigma V) gets smaller?
The associative strength (V) increases across trials, but increments in V get even smaller - learning is decelerated
What does having a bigger alpha mean?
CSs with higher salience (alpha) condition faster.
But ultimately reach lambda
Overshadowing in R-W model
Two CSs, ‘share’ V
On each trial, each CS takes a slice of pie. Therefore the 2 CSs have to share the pie.
If one is more salient than the other, it will take more from ‘the pie’
Blocking in R-W model
Pre-trained CS starts with high V.
Therefore sigma V alread large when new CS added. Therefore delta V is small on each training trial with added CS.
The pre-trained CS has already taken a large amount of the pie, so less available to be shared between it and the new CS
The Role of Context in the R-W model
The context (i.e. physical chamber) can function as an ever-present CS.
I.e. the animals believe I will get shocked because I am in this box.
Odling-Smee (1975) make rats fear black box?
YES, a tone conditioned with shock (US) in a distinctive chamber (black box; where they usually feel safest).
After being conditioned to think that the dark half was dangerous (being shocked there) the rats choose to spend more time in the light half of the box).
In a perfect contingency case (where the rat got shocked 100%) of the time after hearing the tone, they still showed extremely high preference to stay in the dark room. Whereas the likelihood of getting shocked goes down as they start to spend less time in the dark room - this is because the rats learn to be afraid of the room (afraid of the context) - not the tone like in the 100% reinforcement group.
How to prevent the animal associating to the context?
Durlach’s (1983) demonstrated that signalling extra USs with another CS can rescue conditioning to target CS.
Plug in a different stimulus as well (e.g. tone and light) to prevent the animal relating it to the context as most of the attention will be focused on the light - you are restoring conditioning to the tone and light and diminishing what is learnt about the context.
