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Pavlovian Conditioned Stimuli, Screenshot 2024-07-02 at 11.48.03 AM,…
Pavlovian Conditioned Stimuli
How is Learning Expressed
in Behaviour?
sign tracking
: tracking a sign that signals something else.
One of the first protocols that was used that revealed the information that signals can potentially contain.
Signals are very powerful > attracts the animals even if it takes them away from where they have to be.
Stimuli that signal attractive events (food, fluid, sexual partners) come to elicit approach and consummatory responses.
These stimuli convey information about the commodities that they signal.
Other commodities/attractions include the effects produced by drugs of abuse.
Stimuli that signal such effects elicit approach and a range of drug-related responses in people.
People do sign-tracking as well
Pigeon experiments
> the pigeon pecking at the light that it has been conditioned to learn a relationship between it and food/water.
The pigeon pecks at the light in the same way it would open its beak to eat/drink water.
The pigeon can’t not peck at the light.
sign-tracking vs goal-tracking in rats
Individual differences in sign vs goal tracking are related to how readily rats acquire drug-related habits > sign-trackers are more likely to become addicted than goal-trackers.
Sign-tracking is held to reflect the processes involved in drug addiction where drug-related cues acquire so-called incentive salience (power to incentivise behaviours when they ought not to).
Relative to goal-trackers, sign-trackers are more likely to imbue the lever and drug-related cues with such salience.
Sign-trackers will interact with what signals the reward > if a lever appearing in a box signals food, the sign-trackers will interact with the lever when it appears(pressing, sitting, biting, etc), but goal-trackers will go to where the food will be.
problem solving and preparation
problem solving
Pavlovian conditioning has evolved to help us solve the problems of our experience and to prepare us for the world in which we live.
Food selection: omnivores (people) can eat almost anything. So how do we take what is actually edible and reject the rest?
Human infants are born with a liking for sweet tastes and a dislike of bitter ones but have no innate preference for smells > how do we come to like some flavours (taste-smell experiences) or reject others?
People come to like the flavours associated with the effects produced by drugs, such as the flavour of cigarettes, alcoholic beverages, and coffee.
In each case, the flavour starts from a neutral or even a negative hedonic value but acquires a positive hedonic value because it signals the effects produced by nicotine, alcohol or the coffee.
preparation
increases reproductive fitness
japanese quail study psyc1029
promotes defence
Learning to identify cues that signal danger is an adaptation that emerged early in the evolution of animal life.
This learning allows people and animals to anticipate the danger and, thereby, respond appropriately: sympathetic nervous system arousal, decreased pain sensitivity, protective reflexes, “fight or flight”, and freezing.
Pavlovian conditioned responses are shaped by biology.
When Does Learning Occur?
temporal contiguity
Association by temporal contiguity is one of the oldest ideas in the study of learning.
Two events are more likely to be associated when they occur together than when their presentations are separated in time.
This likely reflects the nature of the physical world:
Events that occur together are more likely to be related to each other than events that occur separately.
However, temporal contiguity isn’t NECESSARY for learning;
we learn about relations between events that are separated by considerable delays and, on occasion, we learn about relations between events that have simply never occurred together.
Temporal contiguity isn’t SUFFICIENT for learning;
the blocking effect.
Prior learning can block learning about different contiguous events > learning about the CS fails when it is accompanied by a better predictor of the us.
contingency
there needs to be information between the contiguous events in order to learn.
Animals and people are sensitive to the contingency between two events, and to the contingency between an action and an outcome.
Learning mechanisms are designed to detect:
Predictive relations between events (pavlovian)
Causal relations between actions and events (instrumental)
An otherwise effective CS-US relation can be rendered ineffective when the CS is accompanied by a better predictor of the US.
Learning involves predictions and is driven by errors in these predictions;
Initially, the US is surprising and subjects learn about the CS.
The more they learn, the less surprising the US is.
Learning ceases when the CS predicts the US so that it is no longer surprising.
All the cues present are used to calculate the error (error correction theories).
The size of the error determines the amount of learning.
The sign (pos (more than expected) or neg (less than expected)) of the error determines whether learning is excitatory or inhibitory.
Extinction
Extinction occurs when an already-conditioned stimulus is presented in the absence of the US
Responding to the CS declines across the CS alone presentations; eventually, it ceases altogether, at which point the CS is said to be extinguished.
The Rescorla-Wagner model explains extinction as the gradual weakening and eventually erasure of the CS-US association.
Signature characteristics of extinction
Rapid reacquisition
of responding when the CS-US contingency is reestablished.
Reinstatement
of responding following re-exposure to the US
Spontaneous recovery
of responding with the lapse of time since extinction
Renewal of responding
when the CS is tested outside the context where it had been extinguished.
Extinction results from interference
If extinction had erased the original CS-US association, then there would be no reacquisition, etc.
The fact that these characteristics exist show that:
Extinction involves new learning (CS-noUS).
This new learning is encoded with respect to the extinction context, which includes the time, place, and motivational state of the subject
When the test context matches the extinction context, the CS-noUS learning is retrieved and interferes with expression of the CS-US association in behaviour
When the test context differs from the extinction context, the CS-noUS learning fails to be retrieved and the original CS-US association is expressed in behaviour.
