3 - Learning Theory

Question 1

Non-Associative Leraning

Answer 1

• when an animals behaviour towards a stimulus changes without the presence of an associated stimulus (reward/punishment)

Question 2

Associative Learning

Answer 2

• ideas and experiences reinforce each other and can be linked to one another
  > an animals behaviour towards a stimulus changes due to experience with that stimulus

Question 3

Habituation

Answer 3

(opposite of sensitisation)

• to become accustomed to something
• decreased responding over a series of repeated exposures to the same stimulus
• habituation is not permanent
• dishabituation can occur
• habituation is stimulus specific

Question 4

Sensitisation

Answer 4

(opposite of habituation)

• increased responding over a series of repeated exposures to the same stimulus
• can occur with intense stimuli
• can occur in the early stages of habituation

Question 5

Dishabituation

Answer 5

• being increasingly stimulated by a new stimulus, relative to a stimulus you have been habituated to

Question 6

Kamin’s blocking experiment and what it shows about surprise in learning

Answer 6

A = stimulus
B = stimulus
\+ = outcome (US)
- = lack of outcome
? = no outcome applied but a human expectation of an outcome

Kamin’s blocking experiment comprised of two (learning) phases and a test phase
Phase 1
- the animal was exposed to a noise, Stimulus A (A), followed by a shock (+)
- A+
Phase 2
- the animal was exposed to A, then a light, stimulus B (B), followed by a shock (+)
- AB+
Test Phase
- exposed to B and was measured on it’s expectance of a shock (by it’s behaviour, freezing)
- B?

(the control group had only Phase 2 (CD+) and the Test phase (D+))
Results showed that the experimental group did not expect the outcome (+) when exposed only to the light (B), as they had been conditioned to expect + from A
The control group however, did expect + after exposure to D

• these findings showed that surprise is essential for learning
• shown by the experimental group not being surprised by the outcome (+) in phase 2 (AB+) due to the presence of A, even though B was present also, because they had already gone through the surprise of + linked to A and begun to expect it. Thus failed to learn an association between the light and the shock
• in this case the BLOCKED stimulus is B

Alternate phase 2 (UNBLOCKING):

• the experimental group is exposed to AB++ (double shock)
• this resulted in the experimental group expecting a shock when exposed to only B in the test phase
• as they had gone through the surprise of a second shock due to B in phase 2, and learned to associate B with +

Question 7

Rescorla-Wagner model of classical conditioning

Answer 7

The Rescorla-Wagner model of learning is based on the principle of Error Driven Learning
- stating that if an outcome occurs that you haven’t predicted, you’ve made an error in your prediction, and the magnitude of error affects how strongly the association forms

• the strength of a Classical Conditioned Response depends upon the strength of the connection between internal representations of the CS and the US
  > the associative strength of the CS
• The change in associative strength is directly related to the discrepancy between an asymptotic value set by the magnitude of the US (λ), and the sum of the associative strengths of all the stimuli present on the trial
• The change in associative strength of a stimulus on any trial is determined by the discrepancy between λ and the sum of associative strengths of all the stimuli present on the trial

When graphed on a scale of associative strength due to number of trials, it produces an Asymptotic curve

Question 8

What is shown when the Rescorla-Wagner model is graphed on a scale of associative strength due to number of trials?

Answer 8

an Asymptotic curve

Question 9

Rescorla-Wagner model and Summation

Answer 9

𝚫V = λ - ∑V

• because the equation contains a ‘summed error’ term (∑V), if two stimuli (cues) are trained in compound (together) they both compete for associative strength with the paired outcome
• if trained with AB+, the association between A and + (and B and +) will be half as strong as if trained with only C+

Question 10

Example experiment of conditioned inhibition and summation

Answer 10

Summation Experiment:
Training phases:
- A+
- AB-
- C+
Test phase:
- C?
- BC?
- AC?
Results:
- BC showed a lower conditioned response than C
- AC showed twice the response of C
- Thus B is the conditioned inhibitor, and reduces expectation of outcome

Question 11

What is Conditioned Inhibition?

Answer 11

• specifically predicts the absence of an outcome

- requires an outcome to be expected (due to training)

Question 12

Define retardation of acquisition and give an experimental example

Answer 12

Retardation of acquisition is a reduced ability to learn an association between stimuli, after having already learned a conflicting association

Retardation of acquisition test:
Training:
- A+
- AB-
Test (learning stage 2):
- A+
- B+
Results:
- A+ shows an asymptotic curve of learning when the CS (A) is paired with a UCS (+)
- B+ shows retarded learning when an inhibitor (B) is paired with a UCS (+)

Question 13

What is Long-term Potentiation (LTP)?

Answer 13

A biological model of learning

Donald Hebb proposed a learning theory stating that when individual neural cells are fired at the same time, they establish connecting synapses or strengthen existing ones (what fires together wires together)
(connectionist)

Question 14

Bliss and Lomo Experiment on LTP

Answer 14

Bliss and Lomo Experiment:

• brief pulses of current are delivered to a neuron and the magnitude of response is measured in neurons that are know to receive projects from neuron A
• this measures the stable baseline response (EPSP) to the stimulation
• then stimulation is changed to a burst of high frequency pulses. This is called the training stimulus
• after a brief rest period, the original test pulse is presented again, and the magnitude of response (EPSP) is now greater than before
• thus the test has shown LTP
• this synaptic change can be adopted as a model of how simple associative learning might occur biologically
• under optimal lab conditions, this enhanced response can persist indefinitely

Question 15

Evidence that dopamine supports learning by signalling prediction errors (Schultz)

Answer 15

Shultz found that most midbrain dopaminergic neurons exhibit burst activity (phasic activation) following primary food and liquid rewards.
Also that dopaminergic neurons exhibit phasic activation following conditioned reward-predicting stimuli

Shultz found that dopamine release is sensitive to the prediction of an outcome and the outcome itself
Thus dopamine neurons code for error prediction

Dopamine neurons code for reward

(problematic that Shultz uses a reward system, when Kalin used a punishment system)

Question 16

Effect of an unexpected reward on dopamine activity

Answer 16

Increased Phasic activation

Question 17

Effect of primary food and liquid rewards on dopamine activity

Answer 17

Increased phasic activity

Question 18

Effect of conditioned reward-predicting stimuli on dopamine activity

Answer 18

increased phasic activity

Question 19

Effect of a conditioned reward-predicting stimulus followed by no reward on dopamine activity

Answer 19

decrease in phasic activity

Question 20

Effect of a blocked stimulus followed by no reward on dopamine activity

Answer 20

no neuronal change

Question 21

Effect of a well-learned conditioned inhibitor followed by no reward on dopamine activity

Answer 21

no neuronal change

Question 22

Effect of a well-learned conditioned inhibitor combined with a well-learned reward predictor on dopamine activity

Answer 22

no neuronal change

Question 23

Effect of a well-learned conditioned inhibitor followed by a reward on dopamine activity

Answer 23

hugely increased phasic activity

Question 24

What is phasic activation?

Answer 24

burst firing activity of neurons

Question 25

Effect of a blocked stimulus followed by a reward on dopamine activity

Answer 25

increased phasic activity

Question 26

3 symptoms of Schizophrenia and how it is related to dopamine (and thus prediction errors)

Answer 26

Schizophrenia is thought to be a dopamine-related disorder, comprised of 3 symptoms: Positive Symptoms: - hallucinations / delusions / thought and movement disorders Negative Symptoms: - flattened affect (reduced emotional expressiveness) / anhedonia (inability to feel good) Cognitive Symptoms: - problems with memory / trouble focussing This is thought to be due to dysfunction of dopamine systems in the midbrain (mesolithic area)

Question 27

Schizophrenics and the blocking effect

Answer 27

Individuals with schizophrenia are observed to show a reduced blocking effect - schizophrenics are able to realise a blocking stimulus quite well

Question 28

Positive Symptoms of schizophrenia

Answer 28

- hallucinations - delusions - thought and movement disorders

Question 29

Negative Symptoms of schizophrenia

Answer 29

- flattened affect (reduced emotional expressiveness) | - anhedonia (inability to feel good)

Question 30

Cognitive Symptoms of schizophrenia

Answer 30

- problems with memory | - trouble focussing

Question 31

What part of the brain is there thought to be a dopaminergic dysfunction in schizophrenics?

Answer 31

Mesolithic area | in the midbrain

Question 32

What are alpha and beta responses? (to a drug)

Answer 32

Koob and Le Moal mapped alpha and beta responses to a drug: Alpha response: - the effect that a drug has on the body (UCs) Beta response: - the body's homeostatic response to the drug, overcorrects in the opposite direction to the effect of the drug (UCR)

Question 33

The role of classical conditioning in tolerance and addiction (CCR) e.g. Epinephrine and Heroin

Answer 33

Classical conditioning effects tolerance and conditioning via: Conditioned Compensatory Responses (CCR) > the body's opposing effect to a drug in order to gain homeostasis > the conditional compensatory response will occur when the outcome (CR) is predicted due to the CS CCR in Epinephrine - UCS = alpha response = increased HR - UCR (CCR) = beta response = decreased HR (by the body) - CR (due to needle) = UCR = beta process CCR in Heroin - UCS = slowed NS = alpha response - UCR (CCR) = sped up NS = beta response - CR (due to needle) = UCR = sped up NS

Question 34

How Conditioned Compensatory Response ties in to overdoses plus Siegel's experiment

Answer 34

An overdose is not normally due to a higher dose of the drug than normal, it's normally due to a reduced Conditional Compensatory Response due to environment (context), which means lower beta response and excessive alpha response to the drug (no CS, thus no CCR) Siegel showed this in his experiment with 3 conditions: Control: - no prior exposure to the drug, subsequently exposed Different Test Environment (DT): - pre-exposed to the drug in one environment, and tested with a higher dose the drug in a different environment Same Test Environment (ST): - pre-exposed to the drug in one environment, then tested with a higher dose in the same environment Results: - near 100% mortality rate in the Control - about 60% mortality in the DT - about 30% mortality in the ST

Question 35

Rescorla-Wagner Equation

Answer 35

𝚫V = λ - ∑V States that: Change in the strength of association (learning) (𝚫V) = Surprise = Outcome (λ) - expected outcome (∑V) (existing associative strength) Thus: 𝚫V = λ - ∑V ((***what about alpha and beta?***)) (λ normally is 1 or 0, in the case of the Kamin blocking experiment, λ is 1 for phase 1 and 2 for phase 2 as it is doubled) it has no real-world values