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Conditional learning

C82NAB Neuroscience and Behaviour . Conditional learning. Charlotte Bonardi. A red light means. A red light means. JAM!!. JAM!!. newspaper. newspaper. journal. peri ódico. shinbun.

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Conditional learning

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  1. C82NAB Neuroscience and Behaviour Conditional learning Charlotte Bonardi

  2. A red light means....

  3. A red light means....

  4. JAM!!

  5. JAM!!

  6. newspaper

  7. newspaper journal

  8. periódico shinbun

  9. Conditional control of associations The same stimulus can be associated with two different outcomes. Which association is retrieved is conditional on the context in which the stimulus is presented. This allows the associations to represent knowledge in a versatile way. The context appears to control access to the CS-->US association. spanish “periódico” “newspaper” english

  10. Conditional control of associations Standard associative theories can't explain this -- the association forms and that’s it. ... maybe associative theory cannot explain all animal learning? Questions: Is conditional control really independent of associative learning? If so, how does it work?

  11. Conditional learning in animals Feature-positive discrimination: light+tone ---> food tone --> nothing

  12. Conditional learning in animals Feature-positive discrimination: light+tone ---> food tone --> nothing Associative theory predicts that the light is strongly associated with food ... and that the tone is not On reinforced trials the light and the tone both acquire some strength; on nonreinforced trials the tone loses it again. As there is only limited associative strength available, eventually the light gets it all, and the tone is left with nothing.

  13. Conditional learning in animals Feature-positive discrimination: light+tone ---> food tone --> nothing Associative theory predicts that the light is strongly associated with food ... and that the tone is not On reinforced trials the light and the tone both acquire some strength; on nonreinforced trials the tone loses it again. As there is only limited associative strength available, eventually the light gets it all, and the tone is left with nothing. But how do you know this is what is happening?

  14. Ross and Holland 1981 • Used the fact that auditory and visual stimuli elicit different behaviours in the rat: • auditory: "headjerk" visual: "rearing" • They examined responding in two groups of animals: • 1 light + tone --> food tone --> nothing • 2 light + tone --> food light --> nothing

  15. Ross and Holland 1981 • Used the fact that auditory and visual stimuli elicit different behaviours in the rat: • auditory: "headjerk" visual: "rearing" • They examined responding in two groups of animals: • 1 light* + tone --> food tone --> nothing • 2 light + tone*--> food light --> nothing

  16. The rats learned exactly according to the Rescorla Wagner model: • light* + tone --> food tone --> nothing • rearing to light • light + tone* --> food light --> nothing • headjerking to tone • But if you don't have the light and the tone simultaneous something else happens...

  17. Ross and Holland, 1981 simultaneous

  18. Ross and Holland, 1981 simultaneous

  19. Ross and Holland, 1981 simultaneous serial

  20. Ross and Holland, 1981 simultaneous rear serial

  21. Ross and Holland, 1981 simultaneous rear serial headjerk headjerk In serial case hard for light to associate with food – so tone can

  22. headjerk headjerk Headjerk response suggests responding is based on the tonefoood association.... and it seems to be stronger after the light! tone food so is the light acting as a switch??? light

  23. headjerk headjerk ...or is it just associated with food too?? tone food Although the light is not closely followed by food, it is always followed by food delivery Maybe the rats headjerk more to the tone when the light has been on because they are already expecting food, and this boosts the headjerk CR elicited by the tone. light

  24. grub up!

  25. grub up!

  26. tone food light We can test this by extinguishing the light-->food association. Will the rats headjerk to the tone when it is followed by the light? If they do, we cannot explain the results in terms of associative learning.

  27. Holland, 1989 Two groups of animals: Group FP: Lighttonefood, tone no food Group PP: Lighttonefood, tone no food...

  28. Holland, 1989 Two groups of animals: Group FP: Lighttonefood, tone no food Group PP: Lighttonefood, tone no food, light no food

  29. Holland, 1989 Two groups of animals: Group FP: Lighttonefood, tone no food Group PP: Lighttonefood, tone no food, light no food If the light-->food association is responsible for discrimination in Group FP, then GroupPP should not show any discrimination. This type of discrimination is called a positive patterning (PP) discrimination.

  30. The light is still controlling responding to the tone, despite the fact that it’s not associated with anything. In these cases standard associative theory cannot explain how the light is controlling responding. The light may be called a conditional cue, a modulator, or an occasion setter. Can get negative occasion setting too – turn OFF an association

  31. SIM light & tone  nothing tone shock noise shock SERlighttone  nothing tone  shock noise shock A normal Pavlovian inhibitor will suppress responding to the noise – a summation test will this also happen in the serial case? Holland & Lamarre, 1984

  32. tone shock so is the light acting as a negative switch??? light tone food or is the light just a Pavlovian inhibitor? light if you can explain the discrimination in terms of regular classically conditioned associations, associative theory can explain it – don’t need any other theory but if associative theory can’t explain result, need something else -- then light is an occasion setter

  33. suppression ratio

  34. Rescorla’s modulation theory (Rescorla, 1985) tone food light Whenever a CS is presented, it must activate the US representation to get a conditioned response. If the light is a positive occasion setter, it lowers its activation threshold -- making it easier for the CS to activate.

  35. Holland’s and-gate theory (1983) tone food light The light acts as an and-gate, allowing activation to flow from the CS to the US, and so elicit a conditioned response.

  36. These theories make different predictions about transfer Suppose you also pair a clicker with food; would you expect the light to elevate responding to the clicker as well? click tone food

  37. click tone food Rescorla’s theory says YES. The light is altering the activation threshold of the food, and will boost responding to any stimulus that is associated with it. light

  38. click tone food Holland’s theory says NO The light is acting as an and-gate for the tone-->food association -- not the click-->food association light

  39. Hundreds of experiments later... Occasion setters do sometimes transfer their effects to other CSs paired with the same US (ii) But this transfer effect is seldom as big as with the original CS Many people have done this experiment (e.g., Holland, 1986; Rescorla, 1985). Here is one example, using rats:

  40. TRAIN light.....tone-->food tone--> no food click-->food

  41. light.....tone-->food tone--> no food click-->food TRAIN TEST light.....tone? tone? light.....click? click?

  42. Holland might say... the animals could confuse (“generalise between”) the two CSs (the tone and the click). This might give a false and weak) transfer effect click light food tone food light

  43. Rescorla might say... animals are “upset” by experiencing novel CS combinations (such as the click and the light) -- this could disrupt responding, and transfer to a different CS. click light food tone food light

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