PSYC 358 1st Edition Lecture 8Lecture Overview-Reinforced devaluation-Formal causes of CS-US associationsClassical conditioning Mechanisms: S-R versus S-S Learning-Holland and Rescorla, 1975: Devaluation-Training in food-restricted rats:-CS-tone----- US food-Response---- foraging behaviors-Devaluation:-Group 1: remained food restricted-Group 2: fed (devalue US)-Results:-G1 responded robustly to CS-G2 responding was weak-Conclusions:-The memory of the US remains integral in the expression of theCR (S-S learning)Classical conditioning Mechanisms: The Blocking Effect-Example-Blocking Effect: The Burrito Scenario-Alcohol CS1-Morning Hang-over US-A new Burrito place stays open until 2am Mmmm Burrito: CS2-Will you stop eating Burritos?-NO! YOU LOVE BURRITOSClassical conditioning Mechanisms: The Blocking Effect--Blocking Effect: Prior conditioning of a CS1 (A) interferes with or “blocks” the development of CS2 (B)-A (CS1) = Alcohol-B (CS2)= Burrito-US = hangover-Test occurs with Burrito alone-Same thing as associative interference-What if the first time you drink enough to get a hangover, you eat a Burrito?-Contiguity is fundamental in learning-2 events occurring together will become associated-Blocking calls this into question-If burrito and Hangover are paired, why aren’t they becoming associated?-The US must be “SURPRISING”-Hangover form Alcohol “blocks” the new association between Burrito and Hangover-If we expect the outcome, learning will not occurClassical conditioning Mechanisms: Rescorla-Wagner ModelRescorla-Wagner Model: The effectiveness of a US is determined by how surprising it is-Surprising: An event is surprising if it is different than expected-Ex.1: Under expectation expect a calculator for birthdayReceive a computer-The US is unexpectedly large  excitatory conditioning-Ex.2: Over expectation expect a big holiday bonusReceive Jelly of the Month Club-The US is unexpectedly small  Inhibitory conditioning-Assumption of R-W Model: US effectiveness depends upon expectancy-Strong CR: high US expectancy. Weak CR – low US expectancy(DeltaV) = k(Lambda – V)-Lambda = Asymptote of possible learning with the US-V = Associative value of CS-(lambda-V) = Surprisingness of the US in a given trial (lambda never exceeds 100)-k = Constant related to salience of CS and US-DeltaV = Learning (delta in associative strength) in a given trial-Trial 1 k * (lambda – V) = DeltaV0.5 * (100-0) = 50-Findings of R-W model:-Initial value of (lambda-V) is large because V=0, no learning has occurred-Large changes in learning (DeltaV) occur early-Late in training, (DeltaV) is low because the strength of the CS (V) nears asymptote (Lamda)Classical conditioning Mechanisms: Rescorla-Wagner Model-Implications-A number of learning phenomena can be predicted by the Rescorla-Wagner Model:-Blocking effect-Loss of associative value despite pairing w/US-Conditioned inhibition-Extinction of excitatory conditioning-US removalClassical conditioning Mechanisms: Rescorla-Wagner Model-Limitations-Unfortunately, the R-W model cannot account for:-Extinction s not the development of the CS+ toward 0, (V=0), but involves the transition of a CS+ to a CS- (V=-100)-Some CS feature simultaneously act as CS+ and CS--Example: sexy outfit + Grandma’s perfume = ????-Contra-Blocking: Some conditioned CS1 augment the conditioning of CS2-Phase 1: CS1 (taste) ---- US (LiCl)-Phase 2: CS1 + CS2 (taste + Odor) ---- US (LiCl)-Test CS2: CS1 augments its associative valueClassical conditioning Mechanisms: Alternative Models-Comparator Hypothesis-Comparator Hypothesis: The CR depends on the comparison between the associative strength of the CS and other cues present during the training of the CS-Excitatory Conditioning-Strength of CS (becomes CS+) > Context (CS-)-Inhibitory Conditioning-Strength of CS (becomes CS-) < Context (CS+)-Extinguishing context-US associations strengthens the CS+ Strength-True-By extinguishing the CS+, the context becomes more strongly inhibitory-True48 multiple rarely does “A and B12 true/falseThe phenomenon of contra blocking supports the rescorlawagner model of associative learning-FALSEKnow the difference between the 3Biological strengthBelongingness-sensory