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Classical and Instrumental Conditioning

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Classical and Instrumental Conditioning Classical and Instrumental Conditioning Lecture 8 1 Basic Procedure for Classical Conditioning CS US (Bell) (Meat Powder) CR UR (Salivation) (Salivation) 2 Major Phenomena of Classical Conditioning • Acquisition – CR to CS Reinforced by US – Response Gains Strength • Magnitude of CR • Probability of CR 3 Acquisition: Trial 1 CS Bell Food US Drops of CR Saliva Time 4 Acquisition: Trial 5 CS Bell Food US Drops of CR Saliva Time 5 Acquisition: Trial 10 CS Bell Food US Drops of CR Saliva Time 6 Acquisition of a Conditioned Response CS ==> US 1 0.8 Positive 0.6 Acceleration Negative Acceleration 0.4 Probability Probability of CR 0.2 The “Sigmoidal” (S-Shaped) Learning Curve is Also Known as an Ogive 0 1 2 3 4 5 6 7 8 9 10 11 12 Trials 7 Two Shapes to the Learning Curve Naïve Organism/ Experienced Organism/ Complex Behavior Simple Behavior Response Strength Response Strength 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Trials Trials 8 Major Phenomena of Classical Conditioning • Acquisition • Extinction – No Reinforcement – Response Loses Strength 9 Extinction: Trial 1 CS Bell Food US Drops of CR Saliva Time 10 Extinction: Trial 5 CS Bell Food US Drops of CR Saliva Time 11 Extinction: Trial 10 CS Bell Food US Drops of CR Saliva Time 12 Extinction of a Conditioned Response CS ==> No US 1 0.8 0.6 0.4 Probability Probability of CR 0.2 0 1 2 3 4 5 6 7 8 9 10 11 12 Trials 13 Major Phenomena of Classical Conditioning • Acquisition • Extinction • Spontaneous Recovery – Rest After Extinction – Retest CS alone 14 Spontaneous Recovery After Extinction CS ==> No US Acquisition Extinction 1 0.8 Spontaneous 0.6 Recovery 0.4 Further Probability CR of Probability Extinction 0.2 (Rest) 0 Trials 15 Re-Acquisition of Extinguished Response CS ==> US Acquisition Extinction Re-Acquisition 1 0.8 Savings in Relearning 0.6 0.4 Spontaneous Probability of CR Recovery 0.2 (Rest) 0 Trials 16 Extinction Below Zero • Extinction Trials Continued After CR Disappears Entirely • Reduced Spontaneous Recovery • Less Savings in Relearning – Slower Reacquisition 17 Major Phenomena of Classical Conditioning • Acquisition • Extinction – Extinction Below Zero • Spontaneous Recovery • Re-Acquisition – CS Reinforced by US – Savings in Relearning 18 Implications of Savings and Spontaneous Recovery • Conditioned Response Not “Lost” • Rather, Inhibited or Suppressed – In Line with Changing Circumstances • Conditioned Stimulus No Longer Reinforced • CR Can be Disinhibited – In Line with Changing Circumstances • CS Reinforced Once Again 19 Major Phenomena of Classical Conditioning • Acquisition • Extinction • Spontaneous Recovery • Re-Acquisition • Generalization – CS0 vs. CS1…CSn – Generalization Gradient 20 The Generalization Gradient 250cps 1 0.9 0.8 200cps 300cps 0.7 Lower 0.6 Higher 0.5 0.4 150cps Original 350cps 0.3 CS Probability Probability of CR 0.2 0.1 0 -5 -4 -3 -2 -1 0 1 2 3 4 5 Test Stimulus 21 Major Phenomena of Classical Conditioning • Acquisition • Extinction • Spontaneous Recovery • Re-Acquisition • Generalization • Discrimination – CS+ (Reinforced) – CS- (Unreinforced) 22 Discrimination Learning CS+ ==> US CS- ==> No US 1 250 cps 0.8 0.6 CS+ 0.4 CS- 200 cps Probability Probability of CR 0.2 0 1 2 3 4 5 6 7 8 9 10 11 12 Trials 23 Review of Classical Conditioning • Vocabulary • Phenomena – Unconditioned Stimulus – Acquisition – Unconditioned Response • Reinforcement – Conditioned Stimulus – Extinction – Conditioned Response – Spontaneous Recovery – Savings in Relearning – Generalization • Generalization Gradient – Discrimination 24 Sensory Preconditioning CS1 Light 1 CS2 Bell CS2 Bell 2 US Food CR Saliva CS1 Light 3 CR Saliva25 Higher-Order Conditioning CS1 Bell 1 US Food CR Saliva CS2 Light 2 CS1 Bell CS2 Light 3 CR Saliva26 Significance of Classical Conditioning • Extends Control of Reflexes to Other Environmental Events – Associations between Events • Ubiquitous (Nervous System) • Pavlov: All Learning is Classical Conditioning (?) • Laws of Classical Conditioning are the Laws of Emotional Life 27 Thorndike’s Puzzle Box 28 Thorndike’s Results 29 Thorndike’s Laws of Learning Law of Readiness Law of Effect Law of Exercise 30 Instrumental Conditioning (Operant Conditioning) • Learn Adaptive Behavior – Through Experience of Success, Failure • Organism Operates on Environment – Behavior Changes Environment • Behavior Instrumental – Obtains Desired State of Affairs • Associations between Behaviors and Outcomes 31 B.F. Skinner’s Operant Chamber 32 Instrumental Conditioning Procedure • Phase 1: Baseline Behavior • Phase 2: Acquisition Phase • Phase 3: Discrimination Learning • Phase 4: Extinction 33 Vocabulary of Instrumental Conditioning • Conditioned Response (No URs) • Conditioned Stimulus (No USs) • Reinforcement – Positive – Negative (Not Punishment) • Acquisition • Extinction • Generalization • Discrimination 34 Schedules of Reinforcement • Continuous • Partial • Intermittent – Fixed Ratio (FR) – Variable Ratio (VR) – Fixed Interval (FI) – Variable Interval (VI) • Differential Reinforcement – Of Low Rates (DRL) – Of High Rates (DRH) 35 Intermittent Reinforcement 36 The Matching Law Herrnstein (1970) • Concurrent VI Schedules – Give Organism a Choice • Key A: VI3 • Key B: VI1 • Response Rate is Proportional to the Frequency of Reinforcement – Also Magnitude, Delay of Reinforcement • Basic Principle of Microeconomics – Supply and Demand • Relative Value of Reinforcers 37 Significance of Instrumental Conditioning • Voluntary Behaviors Come Under Control of Environmental Events – Behavior-Outcome Associations • Ubiquitous (Vertebrates) • Thorndike, Skinner: All Learning is Instrumental/Operant Conditioning (?) • Laws of Instrumental Conditioning Are the Laws of Adaptive Behavior – Habits – Incentives 38.
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