PSY402 Theories of Learning

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PSY402Theories of Learning

• Monday
• November 17, 2003
• Chapter 6, Traditional Theories

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Two Theoretical Approaches

• S-R associative theorists -- inflexible view of
  behavior.
• Mechanistic
• Stimulus acquires ability to elicit response
  through associations formed.
• Cognitive theorists flexible view.
• Mentalistic
• Learning involves recognition and understanding
  of environment.

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Hulls Drive Theory

• Drive motivates behavior and drive reduction is
  responsible for the S-R associative learning.
• Drive an intense internal force.
• Behavior is the combined influence of several
  factors, which can be expressed mathematically.

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Hulls Factors

• Excitatory potential (expectation) SER
  likelihood that an event will occur.
• Drive (D)
• Incentive motivation for reward (K)
• Habit strength (H) strength of the S-R
  association (experience).
• Inhibition also due to experience.

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Sources of Drives

• Unconditioned
• Physiological deprivation, metabolic imbalance.
• Intense environmental events with survival
  consequences.
• Pleasurable stimuli (such as saccharin) even
  without nutritional value.
• Acquired Pavlovian conditioned cues to
  unconditioned drives.

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Habit Strength

• SUR an unconditioned or innate habit strength.
• SHR habit strength acquired through prior
  learning experiences.
• If a response reduces a drive state, habit
  strength increases.
• Drive reduction strengthens the S-R bond until
  behavior becomes habitual.

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Inhibition

• Reactive inhibition -- if a drive persists then
  all behavior is temporarily inhibited.
• Conditioned inhibition continued failure to
  reduce drive resulting in a permanent decrease in
  behavior.
• The second strongest response in the habit
  hierarchy will be performed instead.

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Incentive Motivation

• Hull initially assumed that only drive reduction
  influences the S-R bond.
• Crespi showed that reward magnitude affects
  responding.
• If reward only influenced learning, the change
  should be more gradual.
• Hull proposed that reward also influences
  motivation by increasing arousal.

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Importance of Hulls Theory

• THE dominant theory in the 1930s-1960s.
• Correct in many respects
• Intense arousal can motivate behavior.
• Environmental stimuli can develop the ability to
  produce arousal, motivating behavior.
• Value of the reward influences the intensity of
  behavior.

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Problems With Hulls Theory

• You can get increases in behavior without drive
  reduction
• Olds Milner, direct brain stimulation
• Sensory deprivation motivates behavior to obtain
  stimulation (Harlow).
• Hulls theory does not explain how secondary
  rewards can acquire the ability to increase
  behavior.

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Drive-Induction Theory

• Sheffield -- drive-induction not reduction
  strengthens behavior.
• Rewards produce excitement or arousal which
  motivates responding.
• When secondary rewards are associated with
  primary rewards they elicit the same arousal.
• Also explains Harlows findings.

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Guthries Contiguity Theory

• Guthrie rejected the necessity of reward.
• Contiguity is enough to establish an S-R
  association.
• A response that occurs when a stimulus is present
  will automatically become associated with it.
• Learning is entirely governed by co-occurrences
  contiguity in time.

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Impact of Reward

• According to Guthrie, reward is important, but it
  does not strengthen the S-R association.
• The effect of reward is to change the stimulus
  context present prior to reward.
• New actions are conditioned to this revised
  stimulus context.
• Reward prevents further conditioning of the
  undesired behavior.

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Guthries View of Punishment

• Punishment is a stimulus that can either be
  escaped or avoided.
• If a response terminates punishment, it will
  replace the punished behavior next time that
  context occurs.
• Punishment works only if the response elicited by
  the punishment is incompatible with the punished
  behavior.

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Importance of Practice

• According to Guthrie, learning occurs in a single
  trial.
• The strength of the S-R bond does not slowly
  increase with experience.
• Performance increases because subjects must learn
  which stimuli are consistently present.
• Over time, many different stimuli become
  associated with a response.

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Criticisms of Contiguity Theory

• Guthrie conducted few studies to support his
  theory.
• Accurate parts
• Punishment can intensify inappropriate behavior
  when it elicits a response compatible with the
  punished response.
• Contiguity is essential to prevent conditioning
  of competing associations.
• Not all environmental cues are noticed.

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Impact of Reward

• Guthries view of reward has been disproved.
• If what happens after a response is not
  rewarding, an S-R association is not formed, even
  if the stimulus changes.
• Noble reward size predicts response better than
  recency or frequency (contiguity measures).

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Single-Trial Learning

• All-or-nothing (single-trial) learning has been
  difficult to demonstrate.
• Voeks found single-trial learning of an
  eye-blink response in humans.
• Other studies report gradual learning.
• Spence proposed a threshold explanation of
  single-trial learning using incremental learning
  theory.

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Skinner

• Emphasized the importance of environment
  (reinforcers contingencies).
• Validation of hypothetical constructs interferes
  with analysis of the variables controlling
  behavior.
• Anti-theory