SPED 8013 | Chapter 17: Stimulus Control

What is stimulus control?

  • Stimulus control occurs when
    • The rate, latency, duration, or amplitude of a response occurs more frequently in the presence of an antecedent stimulus than in its absence
  • Stimulus control is acquired when
    • Responses are reinforced only (or more frequently) in the presence of a specific stimulus
      • Known as the discriminative stimulus (SD)
    • And not (or less frequently) in the presence of other stimuli
      • Known as stimulus delta (SΔ )

 The Development of Stimulus Control

Don’t Confuse Stimulus Control with MOs or Respondent Conditioning!

  • Motivating Operations change the momentary value of a stimulus, and have nothing to do with reinforcer availability
  • Respondent Conditioning is based on stimulus-stimulus pairing, all occurring BEFORE an elicited (reflexive) response

Stimulus Generalization

  • Occurs when stimuli that share similar physical characteristics with the controlling stimulus evoke the same behavior as the controlling stimulus

PLACEHOLDER [INSERT 4 PICTURES OF DIFFERENT DOGS]

When looking at the pictures we can generalize and say that they are all dogs, but there are differences as well. They are all different breeds, different sizes, different ages. However, because of shared characteristics we can label them dogs.

Stimulus Discrimination

  • Occurs when new stimuli (that may have similarity to the controlling stimulus) do not evoke the same response as the controlling stimulus

PLACEHOLDER [INSERT 4 PICTURES OF DIFFERENT ANIMALS I.E. 2 DOG, CAT, HORSE]

And we can contrast the generalization example with discrimination. We would label the two dogs as dogs, but we would label the one as cat and the remaining as horse. Though they all have fur, four legs, shape or size, etc. we are able to discriminate their different characteristics.

Stimulus Discrimination and Stimulus Generalization are a Continuum

Development of Stimulus Control

  • Stimulus discrimination training
    • Requires one behavior
    • Two antecedent stimulus conditions (the SDand the SΔ )
  • Responses that occur in the presence of the Sare reinforced (thus, the response increases in the presence of the SD)
  • Responses that occur in the presence of the SΔ are not reinforced (thus, the response decreases in the presence of the SΔ)
    • Can also result in a lesser amount of quality of reinforcement

Again, returning to the “friendly conversation” example:

Concept Formation

  • Not a hypothetical construct or mental process
  • Complex example of stimulus control that requires
    • Stimulus generalization within a class of stimuli
    • Stimulus discrimination between classes of stimuli

Example: Concept of Red

  • Stimulus generalization across all red objects
    • Light red to dark red
    • Different objects (car, ball, pencil)
  • Stimulus discrimination between red and other colors
    • Red ball vs. yellow ball
    • Red dress vs. blue dress

Teaching Concepts

  • Requires discrimination training
    • Antecedent stimulus representative of a group of stimuli sharing a common relationship (examples) are presented, along with…
    • Antecedent stimulus from other stimulus classes (non examples)
  • So that the examples for a stimulus class

Types of Stimulus Classes

  • Feature stimulus class
    • Stimuli share common physical forms (i.e. topographical structures)
    • Stimuli share common relative relationships (i.e. spatial arrangements)
    • Developed through stimulus generalization
  • Arbitrary stimulus class
    • Do not share a common stimulus feature
    • Limited number of stimuli
    • Developed using stimuli equivalence

Stimulus Equivalence

  • The emergence of accurate responding to untrained and non reinforced stimulus-stimulus relations following the reinforcement to some stimulus-stimulus relations
  • Useful for teaching complex verbal relations
    • Reading
    • Language arts
    • Mathematics

Testing for Stimulus Equivalence

  • Must have a positive demonstration on 3 different behavioral tests that represent the following mathematical statement
    • If A=B, and
    • B=C, then
    • A=C
  • Reflexivity
    • Occurs when in the absence of training and reinforcement, a participant selects a stimulus that is matched to itself (A = A)
      • Matching to sample

PLACEHOLDER [INSERT MATCHING GAME PICTURE HERE where all objects are similar]

  • Symmetry
    • Occurs with reversibility of the sample stimulus and the comparison stimulus (if A=B, than B = A)
      • Teach spoken word “bicycle” = picture of bicycle
      • Present picture of a bicycle and participant matches to spoken word “bicycle” (as opposed to “car” or “airplane”)

PLACEHOLDER [INSERT MATCHING GAME FROM ABOVE BUT WITH WORD OF PICTURES INSERTED TO EXPLAIN/represent SYMMETRY]

  • Transitivity
    • A derived (untrained) stimulus-stimulus relation that emerges as a product of training two other stimulus-stimulus relations
      • A = B relation (spoken name = picture)
      • B = C relation (picture = written word)
    • Untrained:
      • A = C relation (Spoken name = written word)

PLACEHOLDER [INSERT MATCHING GAME AGAIN BUT CREATE VISUAL TO MATCH TRANSITIVITY]

Matching-to-Sample

  • Participant observes the sample stimulus
    • The comparison stimuli are then presented
  • Participant makes a selection response
    • Matches are reinforced
    • Non matches are not reinforced
  • Conditional discrimination training (we can think of matching to sample as)
    • Same selection must be correct with one conditional stimulus, but incorrect with one or more other sample stimuli

Factors Affecting the Development of Stimulus Control

  • Consistent use of reinforcers contingent upon the correct responding in the presence of the Sis critical
  • Also important are:
    • Pre-attending skills
    • Stimulus salience
    • Masking and overshadowing
      • Masking interferes with responding, overshadowing interferes with acquisition

Pre-attending

  • A prerequisite skill for stimulus control
    • Looking at instructional materials
    • Looking at teacher when responses are modeled
    • Listening to oral instructions
    • Sitting quietly for short periods of time
  • These may need to be taught before stimulus control procedures are implemented

Stimulus Salience

  • Prominence of the stimulus in the environment
  • Influences attention to the stimulus and ultimately the development of stimulus control

Masking and Overshadowing

  • Methods for decreasing the salience of stimuli
    • Masking = blocks evocative function
    • Overshadowing = interferes with acquisition of stimulus control
  • To limit the negative effects of these:
    • Rearrange the environment
    • Make instructional stimuli more intense
    • Consistently reinforce behavior in the presence of instructionally-relevant stimuli

Using Prompts to Develop Stimulus Control

  • Supplementary antecedent stimuli used to occasion a correct response in the presence of an Sthat will eventually control behavior
    • Response prompts operate directly on the response
    • Stimulus prompts operate directly on the antecedent task stimuli

Response Prompts*

  • Verbal Instruction
    • Vocal
    • Non-vocal (e.g, written, gestural)
  • Modeling
    • A demonstration of the desired behavior
  • Physical Guidance
    • Partially physically guiding the learner’s movements
    • Full physical

*With Intrusiveness being least intrusive with a verbal prompt and most intrusive with a physical prompt

Stimulus Prompts

  • Movement Cues
    • Pointing, tapping, touching, looking at
  • Position Cues
    • Place on stimulus closer to the student
  • Redundancy
    • Stimulus or response dimensions are paired with correct choice

** It’s good to be careful about not accidentally prompting a child during the learning process (i.e. inadvertently looking at the stimulus that we want them to select, always putting the correct stimulus in the same spatial location [left, or middle]etc.)

Transfer of Stimulus Control

  • Prompts should be used only during acquisition
  • Transfer stimulus control from prompt to naturally-existing stimuli quickly using fading

Transferring from Response Prompts

  • Most-to-least prompts
    • Physically guide participant through entire performance
    • Gradually reduce amount of physical assistance
      • Modeling
      • Verbal Instruction
      • Natural stimulus
  • Graduated Guidance
    • Immediately fade physical prompts
    • Follow participant closely with hands
    • Gradually increase distance between hands and participant
  • Least-to-most prompts
    • Provide participant with an opportunity to perform the response with the least amount of assistance on each trial
    • Participant receives greater degrees of assistance with each successive trial without a correct response
  • Time Delay
    • Varying the time interval between the presentation of a natural stimulus and the presentation of a response prompts
      • Constant time delay
        • Begin with a 0-sec delay
        • Then use a fixed delay (e.g. 3 seconds)
      • Progressive time delay
        • Begin with a 0-sec delay
        • Then gradually and systematically increase delay (e.g. in 1 sec. intervals) according to some rule
  • Stimulus Fading
    • Highlighting a physical dimension (e.g. color, size, position) of a stimulus and then gradually fading that exaggerated dimension.
    • Superimposing one stimulus on top of another and than gradually fading it out
  • Stimulus Shape Transformations
    • Use an initial stimulus shape that will prompt a correct response
    • This shape is gradually changed to form a natural stimulus, while maintaining correct responding