Скачать презентацию Lecture 5 Chapter 4 Psych 301 Exam

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Lecture 5 – Chapter 4 Psych 301 Exam

Learning Spanish in High School… Did you use flashcards? …learning the La Calavera means skull Let's say it took 10 trials to learn this association When did the bulk of the learning actually take place? In the first or last trials? In the middle?

Most of the associative learning occurs during the first few trials During the last trials, very little is added to the strength of the association Rescorla/Wagner Model attempted to explain the growth of association mathematically with the equation

Rescorla-Wagner Model What is a model? . . should be able to: Explain behavior & also Predict it! conditioning blocking Extinction Simple mathematical account of how associative strength – conditioning builds up over the course of a learning experiment learning curve

During Conditioning – CS/UCS Learning Curves

Rescorla-Wagner Model Mathematical Equation Vn = c (Vmax – Vn) = Delta (change) V = Strength of Association n = trial c = constant (speed of conditioning - 0 -1) Vmax = asymptote (no more trials- max strength of association) Vn = the strength of association at the beginning of the trial Predicts the precise associative strength in each trial

V = Strength of Association n = trial c = constant (speed of conditioning – 0 -1) Vmax = asymptote (no more trials- max learning) Vn = the strength of association at the beginning of the trial Amount of conditioning for 1 st trial Vn = c(Vmax – Vn) Add

V = Strength of Association Can also account for extinction n = trial C = constant (maximal performance) Vmax = asymptote (best learning – if a CS with UCS is paired) Vn = the strength of association at the beginning the trial Vn = c(Vmax – Vn) …no more pairing of UCS with CS 5 ? ? V 5 = 0. 30 (0 -0. 76) = -0. 21

First Conditioning Trial 1 c (Vmax - Vn) = ∆Vn. 5 (100 - 0) = 50 Vn

Second Conditioning Trial 2 c (Vmax - Vn) = ∆Vn. 5 (100 - 50) = 25 Vn

Third Conditioning Trial 3 c (Vmax - Vn) = ∆Vn. 5 (100 - 75) = 12. 5 Vn

4 th Conditioning Trial 4 c (Vmax - Vn) = ∆Vn. 5 (100 – 87. 5) = 6. 25 Vn

5 th Conditioning Trial 5 c (Vmax - Vn) = ∆Vn. 5 (100 - 93. 75) = 3. 125 Vn

6 th Conditioning Trial 6 c (Vmax - Vn) = ∆Vn. 5 (100 - 96. 88) = 1. 56 Vn

1 st Extinction Trial c (Vmax - Vn) = ∆Vn. 5 (0 - 99. 61) = -49. 8 Trial 1 Vn Vn 99. 61 – 49. 8 = 49. 8

2 nd Extinction Trial c (Vmax - Vn) = ∆Vn. 5 (0 - 49. 8) = -24. 9 Trial 2 Vn Vn

Importance of Model • Only mathematical model of behavior • Best Theory of Classical Conditioning • Early trials more “learning occurs” Kamin (1969)…The amount of conditioning on any trial is determined not only by the UCS (shock) but also the expectation that the CS will occur…no surprise less learning (Kamin)…expect a shock…no learning PS: this model only works when the CS precedes the UCS It does not work so well for the backward sequencing of stimuli

Classical Conditioning UCS S ------ S CS Association between CS & UCS UCR Why not this instead? UCS CS UCR

Test the hypothesis that the association is between CS & UCS vs CS & UCR food UCS tone CS UCR Try and affect association between CS & UCS then measure conditioning Post Conditioning Devaluation: alter value of UCS after conditioning

Test the hypothesis that the association is between CS & UCS vs CS & UCR Holland & Straub (1979) 1. Noise + Food activity (CS) (UCR) Noise activity food UCS noise CS UCR Activity PCD No Activity 2. Post Cond. Devaluation Food + Rotation 3. Noise ? ? …. Significant decrease in movement!

Pavlov: CS becomes the UCS Stimulus Substitution “Substitution Theory”

Jenkins & Moore (1973) Pigeons & autoshaping (Key LT + food) • food: open beak/closed eyes • H 20: closed beak/eyes open Key Light + Food Key Light + Water Just Key Light (water) …”drink key light” Just Key Light (Food) …eat the Key Light”

Classical Conditioning S ------ S Association between CS & UCS types of associative learning Operant Conditioning (instrumental learning) S ------ R Direct link between CS & Response

Operant Conditioning vs Classical Conditioning In Classical Conditioning, the dog’s response has no consequences; it produces no change in the environment. The dog gets the food after the bell is rung whether or not he salivates to the bell. His behavior …response doesn’t matter. In Operant Conditioning, the dog has to pull the latch to get the food. His behavior does matter.

Operant Conditioning The nature of behavior is determined by its consequences whether positive or negative Learning occurs through reinforcements S----R So, in OC the reinforcer is contingent of the response = So, in CC the reinforcer is paired with a stimulus +

Classical Conditioning: A theory that attempts to explain how organisms develop involuntary responses to particular stimuli in the environment B. F. Skinner: (respondent behavior elicited by a known stimulus UCS) Operant Conditioning: A theory that explains how people develop voluntary behavior B. F. Skinner: (operant behavior not elicited by a stimulus)

VH 1 “Behind the Science” Edward Lee Thorndike (1874 -1949) 507 pubs Applied animal to human education Intelligence tests -born Willamsburg, MA - mental telepathy in children - studied at Harvard (James) - hatched chicks in bedroom then James’ basement - Ph. D. Colombia University “Animal Intelligence” - Cats - ”Puzzle Box” - The Law of Effect - First experimental study of rewards -1912 Prez of APA Do animals posses intelligence?

Romanes: Animal learn just like we do…. Naturalistic Observation - Anecdotal Evidence Thorndike did not buy this!. . just coincidence Anthropomorphizing “How long would it take an animal to discover how to get out of a box? ” Would this time decrease with exposure to task? Large box (crate) Place hungry cat in Placed food just outside box Cat could see out Could get out by pulling string attached to latch

Some of Thorndike’s actual cat puzzle boxes

Puzzle Box - Scramble -Claw & bite -Stumble on string -Latency shorter -2 nd trial… again scramble…

Thorndikes Conclusions 1. Behavior is highly variable 2. Course of learning is erratic 3. Gradual improvement over trials 4. No suggestions of “sudden insight” 5. No suggestion of any “mental process” 6. Not a rational understanding but an association with the escape with the food reward

Thorndike theory of connectionism: Through experience neural bonds (connections) are formed between stimuli & responses Intellect facilitated neural bonds higher intellect = forms more bonds lower intellect = forms less bonds Genetic Content of intellect (f) experience

Law of Effect (1911) The presentation of a reward strengthens the connection between the response that precedes it and the stimuli presented at the time Behavior that produces satisfying consequences will be repeated, and behavior that produces dissatisfying consequences will not be repeated

VH 1 “Behind the Science” Burrhus Fredric Skinner (1904 -1990) - BA in English -Wanted to be a writer -Master’s In Psych – 1930 -Ph. D – 1931 – Harvard -Dept. Chair, Indiana 1945 -Harvard, 1948 -Father of Operant Conditioning -Radical Behaviorism Skinner strongly championed Thorndikes Law of Effect Invented a number of devices for studying OC (“operating on the environment”)– Skinner Box, Teaching Machine

Radical Behavorism: Not a science but a philosophy… Did not rule out mentation, introspection, self-knowledge “…things that take place in the private world of the skin…” are observable…but cannot infer causes of behavior “The organism becomes a person [i. e. , a unique individual] as it acquires a repertoire of behavior under the contingencies of reinforcement to which it is exposed in its lifetime. The behavior it exhibits at any moment is under the control of a current setting. It is able to acquire such a repertoire because of processes of conditioning, to which it is susceptible because of its genetic endowment. “ (Skinner, 1974)