Discrimination

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					Discrimination & Complex
     Stimulus Control
        Chs12 & 13
     Reinforcement-Based
        Discrimination
              SD           After



Before      Behavior



              SD           After
   Discriminative Stimulus            (S D)


• A stimulus in the presence of which a
  particular response will be reinforced or
  punished
               S-delta    (S D)


• A stimulus in the presence of which a
  particular response will not be reinforced or
  punished
       Reinforcement-Based
          Discrimination
                   SD          After
              Brelandlesss   Chicken
              target         has food


  Before       Behavior

Chicken       Chicken
has no food   pulls the
              trigger
                               After
                   SD        Chicken
                             has no food
                Breland
       Discrimination Training
             Procedure
• Reinforcing or punishing a response in the
  presence of one stimulus and extinguishing
  it or allowing it to recover in the presence of
  another stimulus.
       Stimulus discrimination
          (stimulus control)
• The occurrence of a response more
  frequently in the presence of one stimulus
  than in the presence of another, usually as a
  result of a discrimination training procedure
  Differential Reinforcement vs.
     Stimulus Discrimination
               One Stimulus      Two Stimuli


One Response   No                Stimulus
Class          differentiation   discrimination
               or
               discrimination
Two Response   Response          Combined
Classes        differentiation   differentiation &
                                 discrimination
               Concept training
• Intuition?
  – Control by a concept or set of contingencies the
    person or organism does not define or describe
• Concept of PERSON is complex
       Herrnstein & Loveland
• Concept training procedure with nonverbal
  animal
           Concept Training
                    SD
                                After
                Various
                              Pigeon has
                pictures of
                              grain
                people

  Before         Behavior

No grain        Pigeon
                pecks key


                  Sdelta
                                 After
                Various
                              Pigeon has
                pictures
                              no grain
                with no
                people
           Concept Training
                    SD
                                After
                Various
                              Pigeon has
                Picasso
                              grain
                paintings

  Before         Behavior

No grain        Pigeon
                pecks key


                  Sdelta
                                 After
                Various
                              Pigeon has
                painting by
                              no grain
                others
    Complex Stimulus Control
• Conceptual stimulus control
      Stimulus class (concept)
• A set of stimuli all of which have some
  common physical property
• A stimulus class is the same thing as a
  concept
       Stimulus generalization
• The behavioral contingencies in the
  presence of one stimulus affects the
  frequency of the response in the presence of
  another stimulus
• E.g. – reinforcement for pecking in
  presence of 1 Picasso painting affects
  likelihood of pecking in presence of another
  Picasso painting (more likely)
           Concept Training
• Reinforcing or punishing a response in the
  the presence of one stimulus class and
  extinguishing it or allowing it to recover in
  the presence of another stimulus class
     Concept training

            Vs.

Conceptual stimulus control
    Conceptual stimulus control
• Responding occurs more often in the
  presence of one stimulus class and less
  often in the presence of another stimulus
  class because of concept training
         Testing for stimulus
           generalization
• Test for stimulus generalization using novel
  stimuli
• If respond correctly to novel stimuli, can
  say the behavior is under the stimulus
  control of concepts.
    Stimulus generalization vs.
      stimulus discrimination
• Responds in presence of SD but not in the
  presence of SD. This is ______________

• Responds at similar rates in presence of S D
  and SD. This is __________________
                           Stimulus Generalization
                      60

                      50
Number of Responses




                      40

                      30

                      20

                      10

                       0
                             red   green   blue   yellow
                           Stimulus Discrimination
                      45
                      40
Number of Responses




                      35
                      30
                      25
                      20
                      15
                      10
                       5
                       0
                             red   green   blue   yellow
Stimulus-Generalization Gradient
                      350
Number of Key Pecks




                      300
                      250
                      200
                      150
                      100
                      50
                       0
                            Blue     Yellow-     Red
                                      green
                                   TEST COLORS
Generalization vs. Discrimination
• Amount of generalization is the opposite of
  the amount of stimulus discrimination
  (stimulus control)
Fading, Errorless Learning,
         Imitation
     Chapter 13 & 14, Part 2
                    Fading
• Stimulus dimensions
  – The physical properties of stimuli
        Stimulus Dimensions
• Stimuli differ from each other          vs.
  – House vs. car
• Obvious dimensions
  – Size, weight, shape, material, etc.
        Stimulus Dimensions
• The more dimensions along which objects
  differ, the easier to establish a
  discriminative stimulus control
• The fewer dimensions along which objects
  differ, the harder it is to establish
  discriminative stimulus control
                    Example
•   Good golf balls (SD) vs. bad golf balls (SD)
•   This is a discrimination that is difficult
•   How can the discrimination be established?
•   The 2 golf balls are similar in so many
    dimensions….and differ in only a few
    – Roundness, resiliency, hardness of cover
Make stimulus dimensions more
   salient, then use fading

•   Color the bad golf ball green
•   Leave the good golf ball alone
•   Reinforce picking out good golf balls
•   Don’t reinforcer picking bad (green) golf
    balls
                  Fading
• Gradually fade out the difference between
  good balls and bad balls by reducing the
  “green”
             Fading procedure
• At first, the SD and the SD differ along at least two
  stimulus dimensions (green & white, new & old).
• The difference between the SD and the SD along all
  but one dimension is reduced until there is no
  difference along the reduced dimensions.
• The the SD and the SD differ along only one
  dimension
      Errorless Discrimination
             Procedure
• The use of a fading procedure to establish a
  discrimination, with no errors during
  training.



            Jimmy
Jimmy

Susan
Jimmy

Susan
Jimmy

Susan
Jimmy

Susan
Jimmy

Susan
Jimmy

Susan
      Reinforcement-Based
         Discrimination
                  SD          After
             Jimmy on a     Jimmy has
             white         a raisin
             black card

 Before       Behavior

Jimmy has    Jimmy
no raisin    picks card

                              After
                  SD
                            Jimmy has
              Susan on a
                            no raisin
              black card
        Stimulus Dimensions
• Lettering
• Shading

• At first, choice of cards was under the
  control of the dimension of ________
• Then, after fading, responding was under
  the control of the dimension of _______
  Techniques of Gradual Change
Procedure    Area of           Purpose
             Application
Shaping      Response          To bring about a
                               response not made by
             differentiation   the organism
                               To maintain responses
Reinforcer   Type & amount     already made or to
Reduction    of reinforcer     establish a particular
                               pattern of responses
                               To bring the response
Fading       Stimulus          under the control of
             discrimination    stimuli that didn’t exert
                               control initially
        Reinforcer Reduction
• Move from primary to secondary
  reinforcers
• Change from 3 pellets to 1 pellet
                Imitation
• The form of the behavior of the imitator is
  controlled by similar behavior of the model
Imitation Training: Stimulus
       Discrimination
                     SD            After
              Raised arm and     Marilla has
              “do this”          food &
                                 praise

  Before         Behavior

Marilla has     Marilla
no food &       raises arm
praise
                                   After
                     SD
                                 Marilla has
              No arm raised or
                                 no food &
               no “do this”
                                 praise
Imitation Training: Differential
        Reinforcement
                              After
                Behavior
                            Marilla has
               Marilla      food &
   Before      raises arm   praise
 Marilla has
 no food &
                Behavior      After
 praise
               Marilla      Marilla has
               raises arm   no food &
                            praise
            Training Imitation
• Train imitation with a partner
  –   Touch nose
  –   Touch toes
  –   Raise hand
  –   Etc……
        Generalized Imitation
• Imitation of the response of a model without
  previous reinforcement of imitation of that
  specific response.

				
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posted:9/7/2011
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