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There are two types of CS. What are they?
- Excitatory: predicts US
- Inhibitory: predicts no US
How can inhibotry associative strength accrue to the CS (anticipation of absence of US).
- Again, look at Rescorla-Wagner rule
- When B is presented with excitatory A that has already been fully learnt about and US is absent
- When US is absent, λ=0, but ΣVA is positive, which means B will acquire inhibitory associative strength because change in associative strength will be negative
Explain the study which showed that a conditioned inhibitor can protect a conditioned excitor from extinction.
- Lovibond et al (2000)E's inhibitory associative strength was accrued by pairing it with A, which was already conditioned with US
- When paired, the US was absent, which allowed E to accrue inhibitory associative strength.
- Both C and D were trained as conditioned excitors
- They were both presented in an extinction condition (repeated association with no US)
- However, C was paired with inhibitory E
- C showed no extinction, whereas D did
- C: SCR responding in C alone and expectation of shock following C, but not D
When does superlearning happen? Study?
- When inhibitory stimulus is paired with new stimulus which then results in US. As there is a inhibitory CS already, the presence of US is even more surprising.
- Turner et al (2004)
- Asked participants to imagine they were allegisits whose task was to establish specific allergies in their patients.
- Button if they thought allergic, another if they thought neutral
- Banana --> US
- Banana + Mushroom --> No US (Mushroom inhibitory)
- Mushroom + Pear --> No US (Pear superlearning)
- right PFC activation observed during both inhibitory association and superlearning stages.Right PFC activation is sensitive to the magnitude of the prediction
- error regardless of whether the association is excitatory or inhibitory.
[Attention and Learning]. What phenomena doesn't seem to fit the Rescorla-Wagner theory?
- Latent inhibition
- When CS is preexposed (presented with no consequence) prior to conditioning phase(CS-US), subsequent learning that CS→US association is retarded in comparison to learning about a novel stimulus.
Example study of latent inhibition?
- Nelson & Sanjuan (2006)
- Trained participants on video game in which they had to learn not to fire in presence of warning light (conditioned suppression)
- People were significantly slower to learn to suppress mouse-clicking in response to the red sensor when they’d been pre-exposed to it.
- Context specific --> change of scene in the video game between pre-exposure and conditioning, learning of suppression of mouse click was normal.
Why can't Rescorla-Wagner theory explain latent inhibition?
Because there is no prediction error during pre-exposure (outcome neither predicted nor occurs)
What are the two theories that attempt to explain latent inhibition (LI)?
- 1. MacKintosh Theory: The more reliable a CS is for predicting reinforcement, the more attention is paid to it (e.g. Mackintosh, 1975)
- 2. Pearce-Hall theory: The less reliable a CS is for predicting reinforcement, the more attention is paid to it
What is the theory that attempts to explain the latent inhibition (LI) effect?
- Pearce & Hall (Pearce-Hall theory)
- LI is due to loss of attentio to pre-exposed stimulus
- Attention to stimulus required for learning about it
- When outcome is always the same and is perfectly predicted, attention becomes unnecessary
- This is true during stimulus pre-exposure - same outcome with same stimulus, so we start attending to stimulus
- This loss of attention retards subsequent acquisition of CS-US relationship
Which study tested the prediction of the Pearce-Hall theory? Explain.
- Hogharth et al (2008)
- Pearce-Hall theory predicts that sustained attention should be observed when cue is unreliably associated with outcome
- Presented localised visual cues that perfectly predicted either loud noise or no loud noise outcome.
- Relatively few visual fixations once participants learned to anticpate outcomes associated with A and B
- However, when stimulus B paired with outcome on only half of trials, many fixations on cue and thus sustained attention, supporting the theory.