Learning

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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)

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Associative Learning

• Classical Conditioning associating two stimuli
• Operant Conditioning associating a behavior and
  its consequences

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Classical Conditioning

• Pavlovs 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

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Pavlovian Classical Conditioning
Before Conditioning
UCS
UCR
Neutral Stimulus
No Response
During Conditioning
CS
UCR
UCS
After Conditioning
CS
CR
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Pavlovian Classical Conditioning
Before Conditioning
Food (UCS)
Salivation (UCR)
Tone (NS)
No Salivation
During Conditioning
Tone (CS)
Salivation (UCR)
Food (UCS)
After Conditioning
Tone (CS)
Salivation (CR)
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Classical Conditioning to Cure Bed-Wetting
Before Conditioning
Alarm (UCS)
Wake up (UCR)
Full Bladder (NS)
No waking up
During Conditioning
Full B. (CS)
Wake up (UCR)
Alarm (UCS)
After Conditioning
Full Bladder (CS)
Wake up (CR)
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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

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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

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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

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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

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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

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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

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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 TS
  TS
• Results Rats learned to fear the tone only in
  the contingent condition, when the tone predicted
  the shock

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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

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Blocking
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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!

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Rescorla-Wagner Model

• ?Vn c (Vmax Vn)
• V the strength of association between a CS and
  a US
• ?Vn 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)

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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

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Operant Conditioning

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

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Basics of Operant Conditioning

• Operant freely emitted behavior operating on
  the organisms 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

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Reinforcement Punishment

• Positive reinforcement
• Negative reinforcement
• Positive punishment
• Negative punishment

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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

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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
  (Skinners Verbal Behavior, 1957)

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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 Chomskys critique

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Latent Learning Tolman Honzig, 1930   Group 1
never a food reward Group 2 always a food
reward Group 3 food reward after 10 days  
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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)

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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

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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.