Unit 6 Learning.

Transcription

1 Unit 6 Learning 1. Overview 1. Learning 1. A long lasting change in behavior resulting from experience 2. Classical Conditioning 1. Ivan Pavlov 1. Russian Physiologist 2. Found that dogs learn to salivate to simply the sounds that they regularly hear before being fed 3. Developed classical conditioning: 1. neutral stimuli associated with stimuli such as food will produce similar responses as the old stimuli 2. Classical Conditioning Process 1. Unconditioned stimulus (US or UCS) 1. the original stimulus that elicits a response 2. elicits a natural, reflexive response 3. produces the unconditioned response (UR or UCR) 4. if continually paired with a neutral stimulus, they will be associated 2. Conditioned stimulus (CS) 1. a neutral stimulus that is paired with an unconditioned stimulus 2. elicit a conditioned response (CR) 3. Acquisition 1. learning has occurred once the animals respond to the CS without the US 2. repeated pairings of CS and US yield a stronger CR 3. most effective conditioning: 1. present US first 2. introduce US while CS is still evident 4. Ineffective learning methods 1. trace conditioning 1. presentation of CS 2. short break 3. presentation of US 2. simultaneous conditioning 1. CS and US presented at same time 3. backward conditioning 1. presentation of US 2. presentation of CS 3. Extinction 1. The CS no longer elicits the CR 2. Achieved by presenting the CS without the US repeatedly 4. Spontaneous Recovery 1. After extinction, the CR briefly reappears upon presentation of the CS sometimes 5. Generalization 1. The tendency to respond to stimuli that is similar in some way to the CS 1. subjects can be trained to discriminate 6. John Watson and Rosalie Rayner 1. Conditioned Albert (a little boy) to fear a white rat 1. paired it with a loud noise he cries 2. Albert generalized to other fluffy white things

2 2. Illustrates aversive conditioning 7. Higher-Order Conditioning 1. Second order conditioning 2. The CS acts as a US in order to condition a response to a new stimulus 8. Biology 1. We are biologically prepared to make certain connections more easily than others 1. learned taste aversions 1. pairing nausea with a new food 2. helpful for the survival of the species 2. Salient stimuli create a more powerful CR 3. Garcia and Koelling s Experiment 1. illustrated that rats more easily make some connections than others 1. noise with shock 2. nausea with sweet water 3. adaptive 3. Operant Conditioning 1. Definition 1. Learning based on the association of consequences with one s behavior 2. Edward Thorndike 1. Experiment 1. locked a cat in a puzzle cage 2. cat had to get out to get food 3. time required decreased over trials 4. concluded that the cat learned new behavior without mental activity 2. Law of effect 1. if the consequences of a behavior are pleasant: 1. the stimulus-response (S-R) connection will be strengthened 2. the likelihood of the behavior will increase 2. vice-versa 3. Instrumental learning 1. the consequence was instrumental in shaping future behaviors 3. B.F. Skinner 1. Coined the term operant conditioning 2. Skinner box 1. has a way to deliver food to an animal and a lever to press or disk to peck in order to get the food 2. reinforcer- the food 3. reinforcement- the process of giving the food 1. anything that makes a behavior more likely to occur is a reinforcer 4. positive reinforcement 1. the addition of something pleasant 5. negative reinforcement 1. the removal of something unpleasant 6. escape learning 1. allows one to terminate an aversive stimulus 7. avoidance learning 1. enables one to avoid the aversive stimulus all together 4. Punishment 1. Affecting behavior by using unpleasant consequences 2. Positive punishment 1. the addition of something unpleasant 3. Negative punishment

3 1. omission training 2. the removal of something pleasant 5. Punishment vs. Reinforcement 1. Punishment is most effective if: 1. delivered immediately after unwanted behavior 2. harsh 2. Harsh punishment may result in anger or fear 3. Shaping 1. rewarding approximations of the desired behavior 2. increases the likelihood and speed of the subject stumbling upon the desired behavior for the first time 4. Chaining 1. teaching subjects to perform a number of responses successively in order to get a reward 2. example 1. a rat named Barnabus who learned to run through a veritable obstacle course to get food 5. Discriminative stimulus 1. in discrimination, the special conditions under which the subject learns to perform the desired behavior 6. Primary reinforcers 1. are rewarding in and of themselves 2. food, water, rest 7. Secondary reinforcers 1. things we have learned to value 2. praise, the chance to play a video game 8. Money 1. a generalized reinforcer because it can be traded for almost anything 9. Token economy 1. a practical application of generalized reinforcers 2. used in prisons, mental institutions, schools 3. every time people perform a desired behavior, they are given a token 1. can be traded for any one of a variety of reinforcers 10. Premack principle 1. the reinforcing properties of something depend on the situation 2. whichever of two activities is preferred can be used to reinforce the other activity 6. Reinforcement Schedules 1. Continuous reinforcement 1. rewarding the behavior each time 2. best when first teaching a new behavior 1. once behavior is learned, partial reinforcement schedules yield higher response rates 2. Partial-reinforcement effect 1. behaviors will be more resistant to extinction if the animal has not been reinforced continuously 3. Ways they differ 1. what determines when reinforcement is delivered 1. number of responses made- ratio schedule 2. the passage of time- interval schedule 2. the pattern of reinforcement 1. constant- fixed schedule

4 2. changing- variable schedule 4. Fixed-ratio (FR) schedule 1. provides reinforcement after a set number of responses 2. FR-5 schedule 1. subject will be rewarded after the fifth response 5. Variable-ratio (VR) schedule 1. provides reinforcement based on a varying number of responses 2. VR-5 schedule 1. average number of responses required to get a reward is five 6. Fixed-interval (FI) schedule 1. requires that a set amount of time elapse before a response results in a reward 2. FI-3 minute schedule 1. rewards the first response that occurs after three minutes 7. Variable-interval (VI) schedule 1. varies the amount of time required to elapse before a response will result in reinforcement 2. VI-3 minute schedule 1. subject will be rewarded for the first response made after an average of three minutes 8. Variable schedules are more resistant to extinction than fixed schedules 7. Biology 1. Instinctive drift 1. the tendency for animals to forgo rewards to pursue their typical patterns of behavior 2. Animals won t perform certain behaviors that go against their natural inclinations 4. Cognitive Learning 1. The Contigency Model of Classical Conditioning 1. The contiguity model 1. the Pavlovian model of classical conditioning 2. the more times two things are paired, the greater the learning that will occur 3. contiguity (togetherness) 1. determines the strength of the response 2. Contigency model 1. Robert Rescorla 2. a revised version of the Pavlovian model 1. takes into account more complex circumstances 3. rests upon a cognitive view of classical conditioning 2. Observational Learning (Modeling) 1. Albert Bandura 1. studying modeling helped him formulate social-learning theory 2. Species-specific 1. it only occurs between members of the same species 3. Basic components: 1. observation 2. imitation 3. a mental representation of the observed behavior must exist to enable imitation 4. Bobo doll experiment 1. children exposed to adults who modeled aggressive behavior against Bobo doll 2. children left alone with a bobo doll 3. they exhibited almost identical aggressive behavior 4. Bandura and Ross 1963

5 5. showed that children learn violent behavior through observation 3. Latent Learning 1. Becomes obvious only once a reinforcement is given for demonstrating it 2. Edward Tolman s experiment 1. three groups of rats: 1. always got a reward for completing the maze 2. never got a reward 3. not rewarded during the first half of trials, rewarded in second half 2. group 3 1. during the first half their performance was very similar to the group that never got a reward 2. performance improved dramatically and suddenly once they began to be rewarded for finishing the maze 3. conclusion 1. the rats must have learned their way around the maze in the first half 2. performance did not improve because it had no reason to 3. dramatic improvement in second half resulted from latent learning 4. Abstract Learning 1. Understanding concepts in order to secure a reward 2. Studies show that pigeons can 5. Insight Learning 1. When one suddenly realizes how to solve a problem 2. Wolfgang Kohler s Experiment 1. suspended a banana from the ceiling out of reach of a group of chimpanzees 1. room had many boxes 2. chimps spent most time running around in frustration 3. suddenly, they piled up the boxes, climbed up, and grabbed the banana You just finished Chapter 6: Learning. Nice work!