I) Recap of TuesdayA) Formal models of Pavlovian Conditioning1) Blocking2) overshadowingII) Comparator HypothesisA) Ralph MillerB) Acquisition of CS-US association assumed to follow simple contiguity rule1) e.g. Bush & MostellarC) Many “learning” phenomena are actually due to performance processes, not acquisition processes learning/performance distinctionD) Architecture of model1) Subject goes through a CS/US pairing and is tested with presentation of CS X  direct US memorya) If an association has been formed, the association causes a retrieval of a memory of the USb) If there were other events occurring during training (comparator stimuli), those stimuli will be called from memory when the CS is presented [as well as the US which is being retrieved from memory]i) The comparator stimulus was probably also associated with the US  indirect US memoryc) Presentation of CS X directly activates a memory of the US and also indirectly activates a memory of the USi) The two memories are compared to each other and the output of this comparison determines the nature of the response performed2) Response rulea) Direct > indirect= excitatory CRb) Indirect < indirect = Inhibitory CR3) Examplea) Training session: Tone + Light = Shockb) Learningi) Tone/shock associationii) Tone/light associationiii) Light/shock associationc) Test: tone  behaviord) In terms of the modeli) Tone is presentedTone calls to mind a memory of the shockTone calls to mind a memory of the lightLight/shock association calls to mind the memory of the shock alsoii) Comparison process takes placeIf the directly retrieved memory was strong, we should see a strong fear responseIf the indirectly retrieved memory was stronger, we should see inhibitionDecision is made based on the information that’s compared in the animal’s memoryiii) If the two stimuli were presented together and are about the same strength, the one presented (X) should elicit the stronger response because it follows a direct retrieval pathway (rather than indirect retrievalIn a blocking group trial, A is paired with the US on it’s own first and creates a stronger association which then leads to a stronger retrieval in the testTo combat this, extinguish association with stimulus AIII) Cue Competition: cues compete with each otherA) Examples1) Blocking2) Over-shadowinga) Phase 1: Ax+b) Phase 2: A-c) Test x: CR3) Over-expectationa) Phase 1: A+/X+b) Phase 2: AX+i) Small response to Xc) Phase 3: A-d) Text X: CR4) Conditioned Inhibitiona) Training: A+/ AX-i) A becomes a conditioned exciterii) X becomes a conditioned inhibitorb) This can be thought of in context of the comparator hypothesisi) Tests of X should elicit no responseX calls up X-A associations, no X-US associationsFollows the bottom path on the graph and inhibitsc) In the Rescorla-Wagner modeli) Negative associative strengthIV) Extinction of Inhibition: A+ / AX-A) After training Extinction of X1) According to the Rescorla-Wagner model, attenuate Cl2) According to the comparator hypothesis, no effectB) After training extinction of A1) According to the Rescorla-Wagner model, no effect2) According to the comparator hypothesis, attenuate ClV) Attentional Models of ConditioningA) Rescorla-Wagner model- US effectiveness determines how much is learned on a trial1) A US that is surprising is effective2) A US that is predicted is not effectiveB) Attentional models look at the CS effectiveness as determining how much is learned on a trial1) Mackintosh (1975)a) Attention to a CS increases on the next trial when that CS is the best predictor of the US on the current trial, attention to all other CSs will decrease2) Pearce & Hall (1980)a) Attention to CS decreases on the next trial when the outcome is not surprising on current trial; attention to CS increases on the next trial when the outcome is surprising3) Neither of these accounts predict blocking in one trial they are ruled out05/03/2012I) Recap of TuesdayA) Formal models of Pavlovian Conditioning1) Blocking 2) overshadowingII) Comparator HypothesisA) Ralph MillerB) Acquisition of CS-US association assumed to follow simple contiguity rule1) e.g. Bush & MostellarC) Many “learning” phenomena are actually due to performance processes, not acquisition processes learning/performance distinctionD) Architecture of model1) Subject goes through a CS/US pairing and is tested with presentation of CS X  direct US memorya) If an association has been formed, the association causes a retrieval of a memory of the USb) If there were other events occurring during training (comparator stimuli), those stimuli will be called from memory when the CS is presented [as well as the US which is being retrieved from memory]i) The comparator stimulus was probably also associated with the US  indirect US memoryc) Presentation of CS X directly activates a memory of the US and also indirectly activates a memory of the USi) The two memories are compared to each other and the outputof this comparison determines the nature of the response performed2) Response rulea) Direct > indirect= excitatory CRb) Indirect < indirect = Inhibitory CR3) Examplea) Training session: Tone + Light = Shockb) Learningi) Tone/shock associationii) Tone/light associationiii) Light/shock associationc) Test: tone  behaviord) In terms of the modeli) Tone is presented-Tone calls to mind a memory of the shock-Tone calls to mind a memory of the lightoLight/shock association calls to mind the memory of the shock alsoii) Comparison process takes place-If the directly retrieved memory was strong, we should see a strong fear response-If the indirectly retrieved memory was stronger, we should see inhibition-Decision is made based on the information that’s compared in the animal’s memoryiii) If the two stimuli were presented together and are about the same strength, the one presented (X) should elicit the stronger response because it follows a direct retrieval pathway (rather than indirect retrieval-In a blocking group trial, A is paired with the US on it’s own first and creates a stronger association which then leads toa stronger retrieval in the test-To combat this, extinguish association with stimulus AIII) Cue Competition: cues compete with each otherA) Examples1) Blocking 2) Over-shadowinga) Phase 1: Ax+b) Phase 2: A-c) Test x: CR3) Over-expectationa) Phase 1: A+/X+b) Phase 2: AX+i) Small response to Xc) Phase 3: A-d) Text X: CR4) Conditioned Inhibitiona)