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Learning

Learning. What is Learning? Relatively permanent change in behavior that results from experience (behaviorist tradition) Can there be learning that does not result in a change in behavior? Types of Learning Associative Learning (simple, passive, external)

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Learning

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  1. Learning • What is Learning? • Relatively permanent change in behavior that results from experience (behaviorist tradition) • Can there be learning that does not result in a change in behavior? • Types of Learning • Associative Learning (simple, passive, external) • Cognitive Learning (complex, strategic, internal)

  2. Associative Learning • Classical Conditioning – associating two stimuli • Operant Conditioning – associating a behavior and its consequences

  3. Classical Conditioning • Pavlov’s serendipitous discovery • Associating 2 stimuli • The first stimulus is “neutral” – does not produce any response • The second stimulus produces a reflex (unconditioned) response • After the 2 stimuli become associated, both will produce the unconditioned response

  4. Pavlovian Classical Conditioning Before Conditioning UCS UCR Neutral Stimulus No Response During Conditioning CS UCS UCR After Conditioning CS CR

  5. Pavlovian Classical Conditioning Before Conditioning Food (UCS) Salivation (UCR) Tone (NS) No Salivation During Conditioning Tone (CS) Food (UCS) Salivation (UCR) After Conditioning Tone (CS) Salivation (CR)

  6. Classical Conditioning to Cure Bed-Wetting Before Conditioning Alarm (UCS) Wake up (UCR) Full Bladder (NS) No waking up During Conditioning Full B. (CS) Alarm (UCS) Wake up (UCR) After Conditioning Full Bladder (CS) Wake up (CR)

  7. Further Concepts that Apply to Classical Conditioning • Generalization: CR is given to stimuli that are similar to the CS • Discrimination: CR not given to stimuli that are dissimilar to the CS • Extinction: If the CS is presented repeatedly without being followed by the UCS, the CR will diminish or cease • Spontaneous Recovery: Following extinction, the CR will spontaneously re-appear after a delay

  8. Classical Conditioning as Simple Associative Learning • Temporal Contiguity was thought to be sufficient – the CS simply needs to occur immediately prior to the UCS for conditioning to take place • Equipotentiality: any two stimuli could be associated through conditioning

  9. Equipotentiality Falsified • Some stimuli are easier to associate than others • Taste Aversion – only foods become associated with illness, not other stimuli • Garcia & Koelling, 1966 – the “Sweet, bright, noisy water study”

  10. Garcia & Koelling, 1966 • CS = flavor, light, and click (sweet, bright, noisy water) • UCS: 2 conditions • Group 1: UCS = illness (from X-rays) • Group 2: UCS = shock • CR = avoidance (not drinking the water) • After conditioning, tested which features of the CS were associated with each UCS

  11. Garcia & Koelling: Results • Both Groups: CS (sweet, bright, noisy)  CR (avoidance) • Group 1(UCS = shock) • Sweet water  No avoidance • Bright noisy water  Avoidance • Group 2 (UCS = illness) • Sweet water  Avoidance • Bright noisy water  No avoidance

  12. Temporal Contiguity is Not Enough • Contingency: The CS must reliably predict the occurrence of the UCS (Rescorla, 1966) • Informativeness: The CS must provide new information for predicting the occurrence of the UCS

  13. Contingency (Rescorla, 1966) • UCS = shock (S), UCR = fear • CS = tone (T) • Training: two conditions • Random Condition: S TS S T TS S T TS • Contingent Condition: TS TSTS • Results: Rats learned to fear the tone only in the contingent condition, when the tone predicted the shock

  14. Informativeness: Blocking • If an organism has already learned that one CS predicts the UCS, that will block the conditioning of a new CS if the new CS does not provide any additional information • Example: Fear conditioning of a tone blocks conditioning of a light

  15. Blocking

  16. Rescorla-Wagner Model (1972) • A mathematical model of the “strength of association” produced in classical conditioning • Can account for all of the classical conditioning phenomena we have just seen • Uses just one single equation!

  17. Rescorla-Wagner Model ΔVn = c (Vmax – Vn) V= the strength of association between a CS and a US ΔVn= the change in the strength of association between the CS and US on a given trial Vmax= the asymptote for CS-US association strength after learning c = rate of conditioning (how fast the association is learned)

  18. Cognitive Interpretation of Classical Conditioning • Classical Conditioning is more than simple association • The concept of information could explain contingency and blocking • They are not just associating stimuli, they are seeking information from one stimulus to predict the occurrence of the other

  19. Operant Conditioning • The law of effect: behaviors that are followed by good things happen more often • Association: Things that occur together become associated

  20. Basics of Operant Conditioning • Operant – freely emitted behavior operating on the organism’s environment; NOT a reflex response • Reinforcement Contingencies – the consequences that follow a behavior • Reinforcement: increases the frequency of the behavior • Punishment: decreases frequency of behavior

  21. Reinforcement & Punishment • Positive reinforcement • Negative reinforcement • Positive punishment • Negative punishment

  22. Reinforcement Schedules • Continuous vs. Partial • Fixed vs. Variable • Interval vs. Ratio • Examples • Fixed ratio: vending machine • Variable ratio: slot machine • Fixed interval: checking mailbox • Variable interval: checking email

  23. Explaining Complex Learning with Operant Conditioning • Secondary reinforcers - association • Shaping – simple learning in small increments • Chaining – small increments plus secondary reinforcement • Language – association and reinforcement (Skinner’s Verbal Behavior, 1957)

  24. Learning that Could not be Explained by Behaviorism • Latent Learning – learning without reinforcement (Tolman & Honzig, 1930) • Observational Learning – learning without behaving or being reinforced (Bandura, 1977) • Overjustification – when rewards decrease the frequency of behavior (but see Eisenberger & Cameron, 1996 for an opposing view) • Language Acquisition – Chomsky’s critique

  25. Latent Learning Tolman & Honzig, 1930 Group 1: never a food reward Group 2: always a food reward Group 3: food reward after 10 days

  26. Behaviorism Falls Short: Language • Chomsky: “Action in the past” as a property of stimuli is sneaking mental representations in the back door • Association is insufficient to explain language learning: The evidence points to learning RULES • Evidence: Over-regularization (“goed”) • Conclusion: Mere associations between words can not explain language; any adequate theory of meaning must hypothesize internal representations of the rules of language (grammar)

  27. So What was Behaviorism Lacking? • Symbolic Representation – we have internal (mental) representations for things in the external world • Structure – we learn sets of rules for combining symbols (e. g., grammar), not just associations between pairs of symbols

  28. Associative Learning Rises Again? • LSA – Latent Semantic Analysis • A theory of meaning, and a method for computer analysis of the meanings of texts • The meaning of a word = all of the words that co-occur with it in a sample of written text (roughly) • Meaning is just a function of associations of words, not structure (syntax) • How much of language meaning can LSA account for? A surprisingly large amount.

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