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PSY402 Theories of Learning

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Title: PSY402 Theories of Learning


1
PSY402Theories of Learning
  • Monday
  • November 17, 2003
  • Chapter 6, Traditional Theories

2
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.

3
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.

4
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.

5
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.

6
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.

7
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.

8
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.

9
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.

10
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.

11
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.

12
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.

13
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.

14
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.

15
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.

16
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.

17
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).

18
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.

19
Skinner
  • Emphasized the importance of environment
    (reinforcers contingencies).
  • Validation of hypothetical constructs interferes
    with analysis of the variables controlling
    behavior.
  • Anti-theory
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