RBT · Behavior Acquisition · 8 min read
Discrimination Training and Stimulus Control
- Define stimulus control, discriminative stimuli (SD), and stimulus deltas (S-delta), and explain how differential reinforcement establishes stimulus control.
- Distinguish between simple discriminations, conditional discriminations, identity matching-to-sample, and non-identity matching-to-sample.
- Implement discrete trial discrimination procedures accurately according to the written plan while preventing position bias and inadvertent prompting within the RBT role.
Foundations of Stimulus Control and Discrimination
In applied behavior analysis, stimulus control occurs when an antecedent stimulus systematically affects how likely a behavior is to occur; the behavior may become more or less likely in its presence. Stimulus control is demonstrated when a response occurs more reliably in the presence of an SD than in the presence of an S-delta. A discriminative stimulus, or SD, is an antecedent stimulus that signals that reinforcement is available for a specific response. In contrast, a stimulus delta, or S-delta, is an antecedent stimulus that signals that reinforcement is not available for a specific response. For Registered Behavior Technicians (RBTs), understanding these antecedent stimuli is essential for helping clients build meaningful communication, academic, and daily living skills.
To establish stimulus control, technicians implement discrimination training as designed by a supervisor. In discrimination training, the written plan specifies reinforcement for a target response in the presence of the SD and not for that response in the presence of the S-delta. Through this process, differential reinforcement is used to establish stimulus control. When this process is successful, stimulus discrimination occurs, meaning that a learner responds differently to different stimuli. For example, a learner learns to respond to a specific instruction or item that provides reinforcement while withholding that response when that condition is not present.
While discrimination involves responding differently to distinct stimuli, stimulus generalization occurs when a learned response also occurs in the presence of other stimuli that share features with the training stimulus. Both processes are critical components of learning. In addition, prompt fading is often paired with discrimination training to transfer stimulus control from the prompt to the natural SD. Technicians must remember that the ultimate goal of discrimination training is for the target behavior to occur under appropriate stimulus conditions in the natural environment.
Common mistakes
- Assuming a client has mastered a skill when they are actually displaying a position bias, such as always touching the card on the far left.
- Providing inadvertent prompts, such as looking directly at the target card or placing the target closer to the client than the distractors.
- Using a predictable rotation pattern (such as left-center-right-left) instead of following the written plan's predetermined or randomized rotation instructions.
- Modifying array formats, changing error correction procedures, or designing new discrimination protocols independently instead of reporting issues to the supervising BCBA or BCaBA.
Key points
- Stimulus control occurs when a behavior happens more reliably in the presence of an SD (which signals reinforcement is available) than an S-delta (which signals reinforcement is not available).
- In discrimination training, differential reinforcement is used to establish stimulus control by reinforcing responses in the presence of the SD and not in the presence of the S-delta.
- Presenting multiple examples with varying irrelevant features (such as red, green, and yellow apples) can help learners attend to relevant features, but does not necessarily prevent stimulus overselectivity.
- Simple discriminations do not depend on an additional cue, whereas conditional discriminations (such as matching-to-sample) require the learner to respond based on an additional context or cue.
- Position bias occurs when a learner selects an item based on spatial location rather than stimulus features, which technicians reduce by rotating positions per the written plan.
- Technicians must avoid inadvertent prompting, such as gaze cues or uneven card placement, to ensure responding comes under proper stimulus control.
- RBTs implement discrimination protocols, collect objective data, and report persistent biases to the supervising BCBA or BCaBA, never designing or modifying protocols independently.
Practice this section
Explained RBT Behavior Acquisition questions, no account needed. RBT Behavior Acquisition practice test
The full lesson continues with 4 more sections with exam tips, audio in English and Spanish, 5 Check yourself questions and 20 flashcards.
- 1 month
$44.99$22.49 - 3 months
$131.99$65.99 - Lifetime
$269.99$134.99
One payment, no subscription.
See RBT plansAlready a member? Log in
Sample lesson: Positive and Negative Reinforcement25 practice questions on this exam
Each RBT practice test has 25 original questions with the answers explained. No account needed.
Open the RBT practice testsOriginal lesson written for RBT practice · updated October 25, 2026. Exam names are trademarks of their owners; tests.global is not affiliated with them.