LPI T5 Flashcards
Contingency
the fact that the CS providesinformation about the US’s arrival
The Rescorla-Wagner equation is:
ΔV = αβ(λ – ΣV)
The Rescorla-Wagner equation is used to predict the
The Rescorla-Wagner model describes the rate of change in associative strength (between stimulusand outcome or response and outcome or stimulus and stimulus) through conditioning.This model focuses on error driven learning.
Assumptions of Rescorla-Wagner error prediction model with regard tothe unconditioned stimulus (US)
The effectiveness of US depends on how different it is from what isexpected The amount of learning on a given trial is a function of the surprisevalue of the US (more surprise then more conditioning)
What does ΔV mean?
change in associative strength (i.e., the strength of the association between the CS and the US)
What does the α value represent
α is the salience of the CS, i.e., how much the CS grabs your attention. E.g., the salience of a brightflashing red light should be higher than the salience of a plain red square. With a strong CS, α shouldapproach 1, but with a weaker stimulus α should tend towards 0.
What does β mean?
β is the salience or motivational value of the US, the outcome, e.g., the motivational value of chocolateas a US might be higher than the motivational value of lettuce as a US. The more we desire an outcome,the more we will learn about it.
What does the λ mean?
λ is the outcome (the US). This is usually only 1 or 0 – 1 when the outcome or US is present, and 0 whenthe outcome or US is absent.
What does ΣV mean?
ΣV is the sum of all the associative strengths of all the stimuli at the beginning of that trial.
What is central to the Rescorla-Wagner prediction
role of surprise
The strength of a Pavlovian conditioned response (CR) depends upon
the strengthof the connection between internal representations of the CS and the US… theassociative strength of the CS.
Cue Competition: the principle of summation
This means that if two cues are trainedin compound, they will compete for associative strength with the pairedoutcome <img></img>
Conditioned Inhibition
A conditioned inhibitor is a stimulus that predicts the absence of an outcome.
How do you learn that a stimulus predicts the absence of an outcome?
This cannot be established simply by pairing a stimulus with no outcome, as that would just result in nolearning.
Extinction Treatment
in a conditioned inhibition paradigm, remove the reward when the stimulus is presented after it’s trained
What are the three strengths of the RW model?
- the equation allows qualitative predictions
- heuristic value for other associative learning theories
- helped with understanding numerous psychological processes
| The model provides a good account of many of the facts of compound conditioning, BUT not all the effects associated with blocking and overshadowing are consistent with it. What are the strengths
What are the limitations of the RW model?
- no adequate account for the role of surprise when blocking is considered
- no adequate account of extinction
- inappropriate account for discrimination
- inhibition is conceptualised as negative associative strength
What’s Donald Hebb’s (1949) learning theory
When individual cells are activated at the same time, they establish connecting synapses or strengthen existing onesand thus become a functional unit. These are the structuralbases of memory.
Synapse
specialised junction through which neural signals are transmitted from one neuron (the presynaptic neuron) to another (the postsynaptic neuron)
Hebbian synapse
increase its effectiveness as a result of simultaneous activity in the presynaptic and postsynaptic neurons. Such synapses are essential for many kinds of associative learning.
Long-term potentiation (LTP)
main form of synaptic plasticity reflecting theactivity of synaptic information storage processes, and has been identified as the likelycellular correlate of learning and memory
Explain the principle of LTP
One or more axons connected to a dendrite act as source for stimuli -> sudden and strong stimulation leaves some synapses depolarised/potentiated (more responsive to more stimuli) for varying amount of time
What is associativity in long-term potentiation?
The response to axon 2 is initially weak. Briefly pairing it withrapid stimulation in axon 1 strongly depolarizes the dendrite.Afterward, the response to axon 2 (as well as axon 1) is enhanced.
How does the biological basis relate to Pavlovian Conditioning?
This relates to learning, as previous experience has led to a long-term change inthe behaviour of the synapse, and it can be argued that this is related to surprise asthis is a result of a ‘burst of intense stimulation’ – a difference in what was expected(i.e. a prediction error).
What did Schultz 2007 find on the role of dopamine in learning theory?
dopaminergic neurons exhibitburst activity, also known as ‘phasic activation,’following primary food and liquid rewards and conditioned visual, auditory, and somatosensory reward-predicting stimuli