Topics for this week. Why is conditioning in a course on cognition?

Transcription

1 Topics for this week Today: What do animals learn in conditioning? Conditioning and memory. On Thursday: Introduction to spatial learning (films) Psy lecture 4.1 slide 1 Why is conditioning in a course on cognition? Conditioning procedures result in interesting cognitive changes. Simple associative learning is a possible explanation for some more complex things to be covered later. Psy lecture 4.1 slide 2 Review:Instrumental (Operant) vs. Pavlovian (Classical) conditioning Pavlovian Experimenter arranges relationship between 2 stimuli (CS and US). e.g.tone Ë food But many of the same principles apply to both Instrumental Experimenter arranges relationship between a response and a stimulus ( the reinforcer) e.g. bar press Ë food Psy lecture 4.1 slide 3

2 Instrumental learning, the cognitive approach: What is is learned? (press) (food) 1. A response-reinforcer relationship? (press Ë food) Psy lecture 4.1 slide 4 Instrumental learning: What is is learned? (bar) (press) (food) 2. A stimulus - response relationship? Thorndike:: the reinforcer stamps in the S-R association. If it s S - R learning, changing the value of the reinforcer after learning should not affect responding. Psy lecture 4.1 slide 5 A small digression: Animals encode what food is is what Tinklepaugh s monkey Saw banana put in the cup But got lettuce Looks for the banana Scrub jays and rats (last lecture) Remember specific foods (worms, peanuts, chocolate) Psy lecture 4.1 slide 6

3 Learning about the features of events 1. Rats drink two flavor mixtures sweet + sour (sucrose + weak HCl) salty + bitter (NaCl + quinine) 2. Experience 1 member of each mixture by itself Example: sour + illness salty + nothing 3. Test: sweet bitter Which do they drink more of? Why? Psy lecture 4.1 slide 7 Encoding food types in conditioning? a test Phase1. Train: bar press Ë food chain pull Ë sucrose Phase 2. food Ë poison (revalue the reinforcer) Test. Bar pressing and chain pulling If each response is associated with its reinforcer, what will the rat do? -reinforcer learning But some S-R learning too Psy lecture 4.1 slide 8 Instrumental learning: What is is learned? (bar) (press) (food) Both S-R and R- are learned But that s not all.. Psy lecture 4.1 slide 9

4 1. With light on bar press Ë food And with tone on bar press Ë sucrose 2. Devalue one reinforcer, e.g. the food 3. Test: how much does the rat press the bar with light on?... with tone on?... Light and tone signal different reinforcers This is - learning Psy lecture 4.1 slide 10 Instrumental learning: What is is learned? S-R, R-, and S- are all learned But that s not everything.. Psy lecture 4.1 slide 11 Occasion setting Skinner: a stimulus sets the occasion when a response is reinforced. For example, bar pressing reinforced only when a tone is on. In associative terms, what does the tone do? Colwill s experiment (in the book) Psy lecture 4.1 slide 12

5 1. With light on bar press Ë food chain pull Ë sucrose And with tone on bar press Ë sucrose chain pull Ë food 2. Devalue one reinforcer, e.g. the food 3. Test: what does rat do with light on?... with tone on?... Light and tone modulate R - reinforcer associations This is S (R-US) learning. Psy lecture 4.1 slide 13 Example of of occasion setting with honeybees Odor at entrance signals which color has food Mango Ë (yellow Ëfood) Lemon Ë(blue Ë food) Bees learn this FOOD Entrance ODOR Psy lecture 4.1 slide 14 Occasion setting: Conclusions - ( -US) or - (CS-US) associations. Allow animals to use simple associations in a flexible and appropriate way. Psy lecture 4.1 slide 15

6 What is is learned in in instrumental learning? Summary S-R association R-reinforcer association S - reinforcer And S-(R-US) Psy lecture 4.1 slide 16 Context and memory retrieval (Bouton, p. p. 185) Phase 1 Context A Bar press Æfood Tone Æ shock (conditioned suppression) Phase 2 Group 1: Context A Tone Æ no shock(extinction) Group 2: Context B Tone Æ no shock (extinction) Test Group 1: Test in Context A Group 2: Test in Context A Phase 2: Tests transfer of learning across contexts Test: Tests transfer of extinction across contexts Psy lecture 4.1 slide 17 Group Ext-A: Context A Tone Æ no shock(extinction) Group Ext-B: Context B Tone Æ no shock (extinction) Group Ext-A: Test in Context A Group Ext -B: Test in Context A Ext. in A or B: Test in A Psy lecture 4.1 slide 18

7 Ext. in A or B: Test in A So what do we learn? Initial tone-shock learning is retrieved by the tone, even in a new context (B) But the extinction memory is not so well retrieved in a different context. Psy lecture 4.1 slide 19 Wild chipmunks, 3 feeding platforms Memory retrieval and foraging On each day, find the rewarded platform and keep visiting it. What do they do at the beginning of a new day? i.e. what memory do they retrieve? B: food on 2/3 of days A: food on 1/3 of days C: food on 0 days Psy lecture 4.1 slide 20