PSY402 Theories of Learning

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PSY402Theories of Learning

• Friday
• February 21, 2003

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Discrimination Learning

• Important to recognize when reinforcement is not
  available so that responding can be withheld.
• Discriminative stimulus
• SD reinforcement is available (S)
• SD reinforcement is unavailable (S-)
• Conditioned stimuli always produce a response.
  Discriminative stimuli signal the opportunity to
  respond.

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Two-Choice Discrimination Tasks

• The discriminative stimuli are on the same
  dimension
• Red vs green light.
• Need not be presented simultaneously.
• Two-choice discrimination includes one SD and one
  SD .
• Other tasks can use multiple multiple SD or
  multiple SD.

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Three Phases

• Subjects begin by responding equally to both
  stimuli prediscrimination phase.
• Discrimination phase -- with training, response
  to SD increases and response to SD declines.
• Shift back to non-differential reinforcement to
  show that behavior was caused by reinforcement.

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Conditional Discrimination

• Availability of reinforcement depends on the
  condition of a stimulus.
• The stimulus does not always signal the same
  thing.
• More difficult to learn.
• Nissens chimpanzees
• Large, small squares, white or black.
• SD large white, small black.

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Behavioral Contrast

• Behavioral contrast the increased responding to
  the differential stimulus, decreased response to
  SD
• Contrast also occurs with changes in the duration
  of reinforcement.
• VI-10 to VI-3
• Local contrast emotional
• Sustained contrast related to the differential
  reinforcement.

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Anticipatory Contrast

• Williams sustained contrast occurs due to
  anticipation of a future reinforcement
  contingency.
• Not due to recall of past contingency.
• VI-3, VI-6, VI-3
• Compare the first and third VI-3 behavior.
• VI-6 affected the first VI-3 more than the last
  VI-3 -- a prospective effect.

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Occasion Setting

• A conditioned stimulus (CS) can create the
  conditions for operant responding to a second
  conditioned stimulus (CS).
• Occasion setting ability of one stimulus to
  enhance the response to another stimulus.
• The facilitating stimulus does not produce a CR
  by itself.

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SD as an Occasion Setter

• A Pavlovian occasion-setter can increase operant
  responding.
• Example
• A meal elicits CR craving for cigarette.
• Requesting a cigarette after a meal an operant
  behavior caused by CR.
• Conditional occasion-setting
• Second stimulus modifies meaning of first
  discriminative stimulus.

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Conclusions

• An occasion-setter can increase operant
  responding.
• A discriminative stimulus (SD) can increase
  response to a CR (Pavlovian conditioning).
• This implies interchangeability of Pavlovian
  occasion-setters and discriminative stimuli.

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Central Motivational States

• Conditioned stimuli influence operant behavior
  through their effect on motivational states
• Appetitive
• Aversive
• Emotional responses influence operant behavior.