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 – 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 Classical Learning Features • Reflex • Subject’s behaviour does not cause delivery of US • Association of stimuli Temporal Arrangement Short Delay Long Delay Trace Simultaneous Backwards 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 Interstimulus interval CS US Conditioning trial Intertrial interval 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 Pseudoconditioning • Increase in response due to just the US • Sensitization 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 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 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 Results General Anxiety Unpredictable Predictable Before After • Similar anxiety before • Post attack anxiety significantly lower if attack predictable and higher if attack unpredictable • 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 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- Pavlov’s Protocol Trial Type A Trial Type B CS+ CSUS • Randomize trial type presentation Negative Contingency Protocol CSUS • Context cues serve as CS+ Testing for CS• CS- produces absence of CR • No CR – You’ve produced CS– Haven’t learned anything • How to measure nothing… 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 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) 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 Model • Sugar pellets = grazing • Shock = pain of attack • Hedgehog = lion Control Groups • Saw hedgehog, but no shock • Shocked, but didn’t see hedgehog 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 Conclusion • Biologically relevant CSs can cause backward conditioning Emotional Conditioning • • • • Wide range of emotional responses Emotions universal Positive and negative Emotional response to stimulus reflexive • Conditioned Emotional Responses (CERs) John Broadus Watson • Hard-line Behaviorism • British Empiricism (nurture over nature) • Early work with rats • Shift to infant research • Opposed Introspectionism and Freudian theories 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 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 • 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 CoverJones’ counter-conditioning with Peter 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 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. 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 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 Suppression Ratio Suppression Ratio = CS Responding CS Responding + pre-CS Responding • 0 if behaviour entirely suppressed • 0.5 if no suppression Pre-CS CS Calculation S.R. 25 25 25/(25+25)=25/50 0.5 25 0 0/(0+25)=0/25 0 25 15 15/(15+25)=15/40 0.375 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 Biological Predispositions Burns & Domjan (2000) Timberlake & Grant (1975) Taste Aversion • • • • • US = stimulus producing illness UR = illness, nausea, etc. CS = (generally) novel taste CR = nausea Long delay or trace conditioning Theory of Interest • Contiguity • Equipotentiality Premise – Pavlov – Doesn’t matter what you use as CS – Any stimulus can be conditioned to any US Initial Studies • • • • Garcia & Koelling (1966) Garcia, Ervin & Koelling (1966) Difficulty getting published Finally, accepted in Psychonomic Science 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 Results US=shock Water Consumed Water Consumed US=X-ray Pre-cond. Post-cond. Flavoured water “Bright-noisy water Pre-cond. Post-cond. • Violation of equipotentiality • Some CS-US combinations more easily learned • Biological predispositions Scientific Pardigms • If evidence contradicts fundamental premise…reject the evidence • But… sometimes unexpected results are correct 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 Brain Circuitry Cerebral cortex Mossy fibres CS Pontine nuclei Tone CS Auditory nuclei CS Interpositus nucleus CR Red nucleus CR US Climbing fibres Inferior olive US Trigeminal nucleus reflex Cranial UR paths motor nuclei Reticular formation Eyeblink UR & CR Corneal air puff US Eyeblink Exercise • We can do science to it! • Yes, real science with nothing more than a turkey baster, a pencil, and paper.