Stimulus Control of Operant Behavior

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Stimulus Control of Operant Behavior

• Overview of stimulus control of operant behavior

• Discrimination
• Generalization
• Generalization Gradients
• Peak Shift
• Concepts

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I. Operant Discrimination

• Known as the study of discrimination learning or
  stimulus control
• Discriminative stimulus - Signals that
  reinforcement will be forthcoming if the response
  occurs (S or Sd)
• Signals that reinforcement will not be available,
  even if the response occurs (Sv)

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Discrimination

• Animals learn to demonstrate differential
  patterns to responding to different stimulus
  conditions

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Response Pattern

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Resp/Min
S
S-
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II. Generalization

• Similar patterns of responding to similar
  stimulus conditions
• The opposing qualities of discrimination

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III. Generalization Gradients
Early in discrimination training
CS
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Generalization Gradients
Later in discrimination training
CS
8
Generalization Gradients

• Excitatory Pattern of Responding

CS
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Generalization Gradients

• Inhibitory Pattern of Responding

CR
CS-
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Generalization Gradients

• Excitatory of Responding

CS
CR to tone
1 KHz
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Generalization Gradients

• Inhibitory Pattern of Responding

CR to tone
CS-
570 nm
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Predictiveness and Redundancy

• Conditioning will occur to the stimulus which
  most predictive
• An especially salient CS may overshadow the other
  stimuli

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Overshadowing

• Depends upon nature of the environment, the past
  history of the animal and similar issues
• Highly salient stimulus qualities often
  overshadow other stimuli
• Specific features of the stimulus may be attended
  to

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Attention Training

• Relevance must be learned
• Behavior must be demonstrated
• Transfer of training studies
• Paying attention is a separate part of the
  discrimination learning

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Attention Training

• Dimensional shift learning paradigm
• Intradimensional shift - Train to CS quality,
  shift to different type of same dimension (e.g.
  shift from red to blue for CS)
• Extradimensional shift - Train to CS quality,
  shift to different dimension (e.g. from color to
  shape for CS)

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Attention Training

• Extradimensional shift is more difficult

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IV. Process of Generalization

• Extinction builds to CS and inhibition builds to
  CS-
• Early work of Spence 1936, 1937 and Hull 1943,
  1952
• According to Spences theory, excitation and
  inhibition add together in an algebraic fashion

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Peak Shift Phenomenon
CS
Response Strength
CS-
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Peak Shift Phenomenon
CS
Response Strength
CS-
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V. Natural Concepts

• Concepts are related by unifying or common
  properties
• Abstract concepts
• Same or different
• Often not limited to specific concrete qualities

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V. Natural Concepts

• Some processes
• Matching to sample

R
G
R
Peck
Reinforce
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V. Natural Concepts

• Some processes
• Oddity responding

R
G
R
Reinforce
Peck
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V. Natural Concepts

• Wittgenstein in 1953
• It is not clear what specific features or
  qualities are being responded to
• What is a dog?
• What are the qualities of dogginess?

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V. Natural Concepts

• Herrnstein work in the 1980s
• Demonstrated discrimination of natural objects by
  pigeons
• Sort stimuli by water, trees or a particular
  person
• Organisms as simple as pigeons can reliably
  demonstrate this discrimination

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Learning Theory and Memory

• Are there behavioral ways to describe remembering
  and knowing?
• Some procedures include delayed matching to
  sample
• Matching accuracy decreases as a function of time

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Matching Accuracy Over Time
100
Percentage Correct
50
Seconds
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Matching Accuracy Over Time and Sample Duration
100
Percentage Correct
14 sec sample
8 sec sample
4 sec sample
50
Seconds
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Working Memory

• Memory is an active process
• Susceptible to interference
• Retroactive interference - interfering stimulus
  comes after the stimulus to be remembered
• Proactive interference - interfering stimulus
  comes before the stimulus to be remembered

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Working Memory

• Symbolic matching works as effectively as direct
  stimulus matching
• For example, red to vertical lines is remembered
  as well as red to red
• Directed forgetting - stimulus learning is
  followed by a signal that the stimulus is to be
  remembered or not
• It appears memory is an active process

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Spatial Memory and Cognitive Maps

• Memory for places
• Maze learning studies
• Little indication of decay over time
• Tends to be accounted for by a cognitive
  representation of space