PSY402 Theories of Learning

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PSY402Theories of Learning

• 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

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Spences Acquired Motives

• Spence was a colleague of Hull.
• Spence elaborated the idea that reward size
  matters (K in Hulls theory).
• It isnt enough to say that reward size matters
  how specifically does it affect behavior?
• Spence proposed a mechanism.

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Goal Responses

• Reward elicits an unconditioned goal response RG.
• This response produces an internal stimulus state
  SG that motivates consummatory behavior.
• Reward value determines the size of the goal
  response RG.

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Anticipatory Goal Responses

• Cues become associated with reward through
  classical conditioning.
• These produce an anticipatory goal response rG.
• Cues lead to internal stimulus changes sG that
  motivate behavior.
• Thus Pavlovian conditioning motivates approach
  behaviors.

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Amsels Frustration Theory

• Amsel applied Spences theory to avoidance of
  aversive events
• Frustration motivates avoidance.
• Frustration suppresses approach.
• Nonreward produces unconditioned frustration
  response RF.
• The stimulus associated with it SF motivates
  escape behavior.

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Anticipatory Frustration Response

• As with goal states, classical conditioning
  results in anticipatory frustration response rF.
• The conditioned stimuli associated with them sF
  motivate avoidance of a frustrating situation.
• Example car that wont start.
• SF motivates leaving the car, sF motivates
  selling it.

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Mowrers Two-Factor Theory

• Mowrer proposed a drive-based two-factor theory
  to avoid explaining avoidance using cognitive
  (mentalistic) concepts.
• Avoidance involves two stages
• Fear is classically conditioned to the
  environmental conditions preceding an aversive
  event.
• Cues evoke fear -- an instrumental response
  occurs to terminate the fear.

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Mowrers View (Cont.)

• We are not actually avoiding an event but
  escaping from a feared object (environmental
  cue).
• Millers white/black chamber rats escaped the
  feared white chamber, not avoided an anticipated
  shock.
• Fear reduction rewards the escape behavior.

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Criticisms of Two-Factory Theory

• Avoidance behavior is extremely resistant to
  extinction.
• Should extinguish with exposure to CS without
  UCS, but does not.
• Levis Boyd found that animals do not get
  sufficient exposure duration because their
  behavior prevents it.
• Avoidance persists if long latency cues exist
  closer to the aversive event.

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Is Fear Really Present?

• When avoidance behavior is well-learned the
  animals dont seem to be afraid.
• An avoidance CS does not suppress operant
  responding (no fear).
• However, this could mean that the animals hunger
  is stronger than the fear.
• Strong fear (drive strength) is not needed if
  habit strength is large.

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Avoidance without a CS

• Sidman avoidance task an avoidance response
  delays an aversive event for a period of time.
• There is no external cue to when the aversive
  event will occur just duration. Temporal
  conditioning.
• How do animals learn to avoid shock without any
  external cues for the classical conditioning of
  fear?

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Kamins Findings

• Avoidance of the UCS, not just termination of the
  CS (and the fear) matters in avoidance learning.
• Four conditions
• Response ends CS and prevents UCS.
• Reponse ends CS but doesnt stop UCS.
• Response prevents UCS but CS stays.
• CS and UCS, response does nothing (control
  condition).

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DAmatos Acquired Motive View

• DAmato proposed that both pain and relief
  motivate avoidance.
• Anticipatory pain relief responses.
• Shock elicits unconditioned pain response RP and
  stimulus SP motivates escape.
• Classically conditioned cues sP elicit
  anticipatory pain response rP that motivates
  escape from the CS.

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Anticipatory Relief Response

• Termination of the UCS produces an unconditioned
  relief response RR with stimulus consequences SR.
• Conditioned cues elicit an anticipatory relief
  response rR with stimulus consequences sR.
• Example dog bite elicits pain response, sight of
  dog elicits anticipatory pain, house elicits
  relief

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A Discriminative Cue is Needed

• During trace conditioning no cue is present when
  UCS occurs and no avoidance learning occurs.
• A second cue presented during avoidance behavior
  slowly acquires rR-sR conditioning.
• Similarly, in a Sidman task, cues predict relief
  -- associated with avoidance behavior, not the
  UCS.

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How is rG Measured?

• Anticipatory goal responses were initially
  measured as peripheral nervous system (ANS)
  response.
• No consistent relationship between such measures
  and behavior could be found.
• Now, Rescorla Solomon propose that these
  anticipatory states are due to CNS activity
  (brain states).