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Classical Conditioning

Classical Conditioning. Ivan Pavlov. Medical physiologist Digestion Reflexes Fistula. en.wikipedia.org/wiki/File:Ivan_Pavlov_(Nobel).png en.wikipedia.org/wiki/File:One_of_Pavlov%27s_dogs.jpg. Stimuli & Responses. Unconditional

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Classical Conditioning

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  1. Classical Conditioning

  2. Ivan Pavlov • Medical physiologist • Digestion • Reflexes • Fistula en.wikipedia.org/wiki/File:Ivan_Pavlov_(Nobel).png en.wikipedia.org/wiki/File:One_of_Pavlov%27s_dogs.jpg

  3. Stimuli & Responses • Unconditional • Stimuli and responses whose properties are not dependent upon prior training • Conditional (i.e., “dependent”) • Stimuli and responses whose properties occur only after training • US, UR, CS, CR

  4. Classical Learning Features • Reflex • Subject’s behaviour does not cause delivery of US • Association of stimuli

  5. Short Delay Long Delay Trace Simultaneous Backwards Temporal Arrangement

  6. Terms • Conditioning trial • Each CS-US pairing • Intertrial interval • Time from end of one trial to start of next trial • Inter stimulus interval • Time from the start of the first stimulus in pair to second stimulus in trial

  7. Interstimulus interval Conditioning trial Intertrial interval CS US

  8. Measuring Learning • Test (probe) trial • Present CS by itself (no US) • Magnitude • How much CR occurs • Probability • How often CS produces CR • Latency • How soon CR occurs after CS

  9. Pseudoconditioning • Increase in response due to just the US • Sensitization

  10. Controls • Random control • Exp. Gr.: CS-US pairings • Control Gr.: same number of CS & US, but randomized • Explicitly unpaired control • Exp. Gr.: CS-US pairings • Control Gr.: same number of CS & US, but presented far enough apart (even separate sessions) to prevent association

  11. CS Types • Excitatory CS (CS+) • CS predicts the occurrence of US • Activates behaviour related to US • Inhibitory CS (CS-) • CS predicts the non-occurrence of US • Suppresses behaviour related to US

  12. Inhibitory Conditioning • Why predict non-event? • Unpredictable aversive events more stressful • Craske et al. (1995) measured general anxiety in subjects with panic disorder • Predictable and unpredictable attacks • Before and after anxiety ratings

  13. Unpredictable General Anxiety Predictable Before After Results • Similar anxiety before • Post attack anxiety significantly lower if attack predictable and higher if attack unpredictable

  14. Ability to predict aversive event also allows prediction of lack of aversive event • Application: stress management techniques • Can’t eliminate all stressors • Introduce periods of predictable “safety” • Reduces overall stress

  15. Producing CS- • Can produce CS- for either appetitive or aversive US • Most research done with aversives • Inhibitory conditioning (and inhibitory control of behaviour) only if there is also an excitatory context for US delivery • Can’t have CS- without CS+ • But, can have CS+ without CS-

  16. Pavlov’s Protocol • Randomize trial type presentation Trial Type A Trial Type B CS+ CS- US

  17. CS- US Negative Contingency Protocol • Context cues serve as CS+

  18. Testing for CS- • CS- produces absence of CR • No CR • You’ve produced CS- • Haven’t learned anything • How to measure nothing…

  19. Techniques • Bidirectional response • Utilizes opposing responses • Do one with CS+, opposite with CS- • Summation test • Measure CR with CS+ • Compound stimulus of CS+ & CS-; measure CR • Retardation of acquisition • Trained CS- and novel stimulus; pair both with novel US for same number of trials • Measure CR for both • Prior learning of CS- inhibits learning new association

  20. Backwards Conditioning • Inconsistent results across studies • Little learning at all, CS-, CS+ • Keith-Lucas & Guttman (1975) • Backward conditioning and biological plausibility • Predator attacks prey • Antelope grazing • Lion attacks • Antelope clawed, but escapes • Pain (US); proceeds sight of lion (CS)

  21. Experimental Procedure • Rats fed sugar pellets • Give one-time electric shock (US) • Lights go out • 1, 5, 10, or 40 seconds • Toy hedgehog added (CS) • Observe rat one day later

  22. Model • Sugar pellets = grazing • Shock = pain of attack • Hedgehog = lion

  23. Control Groups • Saw hedgehog, but no shock • Shocked, but didn’t see hedgehog

  24. Results • Backward conditioning not seen in controls • In 1, 5, and 10 sec delay groups, got backward conditioning • Avoid hedgehog • Don’t eat much when hedgehog present • Fear induced by hedgehog is CR

  25. Conclusion • Biologically relevant CSs can cause backward conditioning

  26. Emotional Conditioning • Wide range of emotional responses • Emotions universal • Positive and negative • Emotional response to stimulus reflexive • Conditioned Emotional Responses (CERs)

  27. John Broadus Watson • Hard-line Behaviorism • British Empiricism (nurture over nature) • Early work with rats • Shift to infant research • Opposed Introspectionism and Freudian theories

  28. Conditioning of Fear • Watson & Raynor (1920) • Albert B. • Mother a wet nurse at Harriet Lane Home (attached to Johns Hopkins University) • Albert first assessed at about 8 months • Emotionally stable, healthy

  29. Method • Present white rat • No fear • Present white rat and bang metal bar • Produces CER of fear, avoidance, withdrawl • US = noise, UR = startle • CS = rat CR = fear • CER generalizes to other furry objects • Video

  30. Study went for several months • Intended to reverse CER conditioning, but Albert B’s mother ended her job at hospital • Research led directly to Mary Cover-Jones’ counter-conditioning with Peter

  31. What Happened to Albert • Beck, Levinson & Irons (2009) • Historical detective work • Albert B.’s mother probably Arvilla Irons Merritte • Douglas Merritte, born 9 March 1919 • Arvilla Merritte left Johns Hopkins • Worked as assistant for ill wife of farmer • Douglas Merritte died 10 May 1925, probably from meningitis

  32. Name • Why Albert B.? • Ethical concerns with confidentiality not firmly established • Watson may have played “name games” • His sons William and James • His name from John Albert Broadus, Baptist minister… Albert B.

  33. What Happened to Watson • Affair with Rosalie Raynor, his grad student • Divorce, fired, resigned as president of APA • Worked for J. Walter Thompson advertising agency; vice-president within two years • Ponds cold ream, Maxwell House coffee • Published books and articles on childcare • Psychological care of infant and child (1928) • Criticized by many modern child experts/advocates, but not any more extreme than other childcare texts of the time • Strongly advocated against spanking and corporal punishment

  34. Nonhuman Studies of Fear • Typically use shock as US • Rats freeze • SSDS • Conditioned suppression ratio • Train operant response; train CS+ for aversive US, test suppression of operant response in presence and absence of CS • Suppression video

  35. CS Responding Suppression Ratio = CS Responding + pre-CS Responding Suppression Ratio • 0 if behaviour entirely suppressed • 0.5 if no suppression

  36. Sign Tracking • Also now called autoshaping (Brown & Jenkins (1968) • Response not required • US often food • Stimulus (CS) indicates US availability • Subject “tracks” the sign more and more • CS takes on properties of US • Pigeon autoshaping • Longbox autoshaping

  37. Biological Predispositions Burns & Domjan (2000) Timberlake & Grant (1975)

  38. Taste Aversion • US = stimulus producing illness • UR = illness, nausea, etc. • CS = (generally) novel taste • CR = nausea • Long delay or trace conditioning

  39. Theory of Interest • Contiguity • Equipotentiality Premise • Pavlov • Doesn’t matter what you use as CS • Any stimulus can be conditioned to any US

  40. Initial Studies • Garcia & Koelling (1966) • Garcia, Ervin & Koelling (1966) • Difficulty getting published • Finally, accepted in Psychonomic Science

  41. Results • US = poison, CS = novel flavour • Delay between CS and US 5 - 22 minutes produced very strong CR • Weaker, but significant CR (avoidance of flavour) with up to 24 hour ISI! • Violation of contiguity

  42. Results US=X-ray US=shock • Violation of equipotentiality • Some CS-US combinations more easily learned • Biological predispositions Flavoured water Water Consumed Water Consumed “Bright-noisy water Pre-cond. Post-cond. Pre-cond. Post-cond.

  43. Scientific Pardigms • If evidence contradicts fundamental premise…reject the evidence • But… sometimes unexpected results are correct

  44. Eye Blink • US = air puff UR = blink • CS = noise, light, vibration, etc. CR = blink • Straight-forward classical conditioning • Vehicle for examining neurobiology of learning and memory

  45. Brain Circuitry Cerebral cortex Mossy fibres Climbing fibres CS US Interpositus nucleus Inferior olive Pontine nuclei CR Red nucleus CS US Corneal air puff US Trigeminal nucleus Tone CS Auditory nuclei CR reflex paths Cranial motor nuclei UR Reticular formation Eyeblink UR & CR

  46. Eyeblink Exercise • We can do science to it! • Yes, real science with nothing more than a turkey baster, a pencil, and paper.

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