L10 - Variations in processing the US Flashcards
What is the equation for the RWM
(triangle V) = a + B X (Lamda - Sum V)
(Triangle V)
Amount of learning, change in the CS-US association
Lamda
Experience of US presentation
How much learning can be supported to the US
V
how much a subject know about relationship between CS and US
Sum (V)
Expectation of US, based on total associated strength of all CSs present
How much can be predicted from what you know about all of the CSs present
a
salience of CS
B
salience of US
a and B are
Parameters that regulate the rate of conditioning (otherwise all conditioning would be done in one trial)
With Learning Sigma V and lamda are always what on the first trial?
0 and 1
Why bother with a numerical formula?
- If we have a very clearly laid out model it allows us to make PREDICTIONS
- Can design experiments and see if empirical findings match predictions of the model
- It is testable
What does reaches an asymptote mean?
closer to a value of 1
Across trial what happens to associative strength and increments in V
Associative strength (V) increases but increments in V get ever smaller
Overshadowing with RWM
Limited amount of learning possible, two CSs share V
The CS with the larger alpha takes larger lamda proportion per trial, leaving less for other CS
If one is more salient than the other, it will take more of “the pie”
Blocking with RWM
Pre-trained CS starts with high V
Already large sigma V before C2 is added
Change in V is small on each 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
Relative signal Validity with RWM
Extra conditioning trials with L alone means V of L increases faster and blocks conditioning to T
RWM explaining the truly random design
How the RW model explains the truly random design
- We get good conditioning when US is followed by CS - Very bad when extra random ones happen
It isn’t that rats learn nothing just they learn the context that predicts the occurrence of the shocks, not linked to US
The role of context in conditioning
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
What does it mean when the lamda - sigma V gets smaller?
The associative strength (V) increases across trials, but increments in V get even smaller, learning is decelerated
Oding-Smee (1975) black box experiement
Showed that extra “unsignalled” US presentation caused considerable conditioning to context
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.
How do we quantify the no of magazine entries by the rat in a Skinner box?
Every time the rat pokes his head into the magazine, breaks the infra-red beam and quantifies the no of magazine entries
Can think about this as the amount of expectation the rat has about when food is going to be delivered
What did Odling-Smee use in his experiment and why?
Place preference chamber
Rats like more time in the black chamber because they are nocturnal animals
Can treat this as a context
Design an experiment where we vary the contingency of the tone shock association in the black chamber
Allows us to reveal how much is learned to the tone and how much is learned to the context
What did Odling-Smee do to 6/8 conditions in the experiment?
Varied the proportions of contingency between US and CS
Depending on the proportion results in how many times the CS-US pairing occurs in the black chamber
What happened to the rats when they had high proportion of CS-US pairing?
High proportion of CS-US pairing, learn the tone predicts the CS and move out for the shock but still spend most time in black box
Do not associate the US with the context, associate it with the CS
What happened to the rats who had more shocks delivered in the absence of the CS?
Appropriately, less time is spent in the black chamber indicating that the rats are learning that the context should be feared
The US’s are non-contingent on the tone
What did Odling-Smee do to the control groups?
2 control groups
received either CSs
without USs, or
USs without CSs.
