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.