Learning Pt2 PBS5

  1. There are two types of CS. What are they?
    • Excitatory: predicts US
    • Inhibitory: predicts no US
  2. 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
  3. 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
  4. 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.
  5. [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.
  6. 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.
  7. Why can't Rescorla-Wagner theory explain latent inhibition?
    Because there is no prediction error during pre-exposure (outcome neither predicted nor occurs)
  8. 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
  9. 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
  10. 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.
Card Set
Learning Pt2 PBS5
Lec2 - Mechanisms of associative learning (excitatory vs inhibitory; superlearning; attention & learning)