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University of Toronto Scarborough
Rutsuko Ito

lec03 factors that influence conditioning 1. temporal contiguity 2. nature of CS and US 3. causal relevance 4. contingency modeling learning 1. rescorla-wagner model (old theory, but still carries a lot of weight) a. US processing model 2. mackintosh, pearce hall models a. CS processing models 3. dopamine and error prediction a. what does dopamine code for? i. big field of study temporal contiguity 1. closer two stimuli are together, the stronger the association 2. the order of stimuli presentation also matter 3. types of conditioning a. delay i. US presented right after the CS b. trace i. gap between CS and US encourages conditioning 1. where US is presented much later ii. strength of conditioning is not that strong c. simultaneous i. missed this ii. CS and US presented at the same time d. backward i. US presented before the CS ii. order of presentation matters nature of US and CS 1. novelty a. new things conditions more rapidly b. prior exposure to the CS or US can interfere with learning 2. latent inhibition effect / CS-pre-exposure effect a. familiar stimulus becomes irrelevant b. prior exposure to the CS on its own, makes it hard for it to be paired to the US because the CS is already known to be irrelevant to reward i. learning is retarded 1. schizophrenics won't show retardation effect of learning a. why? 3. US-pre-exposure effect a. repeated presentation of the US alone b. pairings of the CS with the US c. result: i. initial pre-exposure to the US usually retards subsequent conditioning ii. conditioning of contextual (background cues) during the pre-exposure phase may already act as a CS 2. slide 7 a. missed what she said in differentiating CS and UR 3. salience of CS and US a. affects conditioning b. how do we manipulate salience? i. change intensity of stimulus 1. more intense, usually better (but not too much) ii. make it more relevant to biological needs 1. e.g. salience of salt taste by depriving animal of salt c. in taste aversion learning (flavor - LiCl pairing) how would you change intensity of CS and US? i. ... similarity 1. similarity a. some stimuli are more readily associated with one another i. internal stimuli go together 1. taste and illness 2. sound and shock ii. external stimuli go together causal relevance 1. causal relevance a. animals attribute a particular effect with its most probable cause i. based on past experience / evolutionary history 1. ... 2. ... 3. ... contingency 1. learning requires more than the coincidence of CS and US a. it requires that the CS predicts the occurrence of the US i. positive contingency 1. possibility of US and CS occurring is greater than possibility of US and no CS ii. negative contingency 1. possibility of US and CS occurring is less than possibility of US and no CS iii. no contingency 1. equal possibility 2. missed explanation of slide 11 3. slide 12 a. best condition for learning to take place is where there is a positive contingency b. missed a little element of surprise 1. Kamin's blocking a. phase 1 i. stimulus A becomes predictor of US 1. A is tone 2. US is shock b. phase 2 i. stimulus A paired with C (compound?) predictor of US 1. C is ??? 2. result a. no learning occurs to stimulus C in block group i. why? 1. ??? 2. stimulus A fully predicts the US 3. so US is no longer surprising rescorla-wagner model 1. mathematical model of pavlovian learning 2. posits that learning occurs on a conditioning trial only if the US is surprising (violation of expectation -- what does this mean???) 3. RW model video a. the more you expect something to happen, the less the learning occurs i. as stimulus continues, learning decreases 4. learning curve a. acquisition curve i. as learning reaches a maximum level, it plateaus off ii. most learning occurs at the beginning iii. least learning occurs at the end b. maximum level of learning denoted by lambda i. maximum value of learning is = 1 c. change in associative strength on a trial denoted by delta V i. delta V denotes amount learnt in a trial ii. depends on 1. salience of the CS and US = alpha a. a constant number 2. how far V (associative strength at beginning of trial) is from the asymptote (lambda) d. effect of US magnitude on lambda i. the bigger the US, the higher the asym
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