Stimulus Control Notes

Stimulus Control

  • Stimulus control occurs when the rate, latency, duration, or amplitude of a response is altered in the presence of a stimulus.
  • Behavior is more likely to occur in the presence of a discriminative stimulus (SD) than in its absence.
  • Behavior must occur less often in the presence of an s-delta for stimulus control to be in effect. If behavior occurs in the presence of both the SD and s-delta, stimulus control is not present.
  • Most behavior is under stimulus control.
    • Example: Saying "blue" in the presence of something blue, but not in the presence of something green.
  • Example in Autism intervention:
    • SD: "Clap your hands."
    • Response: Student claps hands.
    • Consequence: Reinforcer (tangible or social).
  • Need to show when the instructor says "touch your head" the student actually touches their head and does not clap.
  • The instruction needs to show that they're only doing what you want them to do when you provide that instruction.

Stimulus Generalization

  • Stimulus generalization is the tendency for stimuli similar to the discriminative stimulus to evoke the same response.
    • Example: Saying "red" in the presence of a red heart, but also saying "red" in the presence of a pink heart due to similar hues.
  • If we teach red in the presence of a red heart, we might actually see the same occur in the presence of a pink heart as well.

Discrimination Training

  • Discrimination training involves providing reinforcement in the presence of one stimulus but not in the presence of another stimulus.
  • Social behavior is often discriminated.
    • Behavior might differ in the presence of different groups of friends due to different sources of reinforcement.
  • Language development also involves discrimination.
    • Saying "a" in the presence of a, but not in the presence of b.
  • Discrimination training is key in developing language and following directions.
  • Individuals with autism spectrum disorder often struggle with discrimination, requiring systematic teaching.

Simple Discrimination

  • A stimulus functions only as an SD.
    • Touching blue always results in reinforcement.

Conditional Discrimination

  • The stimuli function as both a discriminated stimulus and a stimulus delta with one signaling the availability for reinforcement, and one signals the availability for the absence of reinforcer.
  • Stimuli function as both an SD and an s-delta.
    • Touching blue only results in reinforcement when the instructor says, "touch blue."
    • Touching red is only going to result in reinforcement if the instructor says, "touch red."
  • The response is conditional upon something else.

Differential Reinforcement

  • Differential reinforcement is key to developing discriminated responding.
  • Reinforce in the presence of the SD and provide no reinforcement in the absence of the SD (or in the presence of the s-delta).
    • Example:
      • Touch blue when I say "touch blue" = reinforcement.
      • Touch blue when I say "touch red" = no reinforcement.
      • Touch blue when I don't say anything = no reinforcement.

Common Approaches for Developing Discrimination

  • Discrete trial teaching: The most common approach to developing conditional or simple discrimination.
  • Prompting: Used in discrete trial teaching with prompts faded over time.
  • Shaping: An approach to develop discriminated responding.
  • Chaining: Can also develop stimulus control.
    • Example: Steps to make a cake; one response sets the occasion for another. Task analysis to complete the chain of responses to make a cake.

Recommendations for Developing Stimulus Control (Green, 2001) (in context of matching to sample)

  • Recommendations on how to avoid faulty or undesired stimulus control, specifically in the context of matching to sample.

  • Matching to sample involves matching a sample stimulus to a comparison array.

  • Use a different sample on each presentation.

    • Avoid presenting the same sample (e.g., red) on back-to-back trials.

  • Use at least three comparisons in the array.

    • Using only two comparisons is a 50/50 chance, which may maintain behavior without true stimulus control.

  • Present samples equally across the trial block.

    • If using three samples (red, green, blue) in a block of nine trials, present each sample three times.

  • Balance the correct comparison position.

    • Ensure the correct match appears on the left, center, and right equally across trials.

  • Require an observing response.

    • Ensure the learner attends to the sample before matching.
    • Cover the sample and have the learner unveil it before matching.

  • Use simple instructions.

    • Instead of "touch ball" or "give me the green one," use "blue," "green," or "match."
    • Avoid extra language that could distract the learner or lead to faulty stimulus control.

  • Avoid arranging stimuli in front of the learner.

    • Present the entire array all at once, without arranging in front of the learner.

  • Use errorless teaching.

    • Minimize errors using strategies like most-to-least prompting.
    • Start with the most intrusive prompt level and fade back.

  • Consider the recommendations as guidelines, not strict rules.

    • Be responsive to the learner, as the main source of control for the RBT's behavior should be the learner's behavior.
    • If you find yourself following recommendations or a protocol and ignoring the learner's behavior, stop and adjust.