Discrimination training is a core teaching strategy in Applied Behavior Analysis (ABA). It helps individuals learn to respond differently to different stimuli in their environment. In simple terms, discrimination training teaches learners when to respond and when not to.
The goal is to help learners accurately identify cues, tell them apart, and respond appropriately in real-world situations.
In this blog, we’ll explore:
- Discriminative stimuli (SDs)
- S-deltas
- Stimulus control
- Stimulus discrimination
- Practical strategies for effective implementation
What Is Discrimination Training?
Discrimination training teaches individuals to engage in a behavior only when a specific cue is present and to withhold that behavior when it is not.
Through repeated practice and reinforcement, learners begin to associate certain stimuli with reinforcement and others with the absence of reinforcement.
How Does Discrimination Training Work?
Discrimination training follows a predictable pattern:
- A discriminative stimulus (SD) is presented, signaling that reinforcement is available.
- The learner responds correctly by engaging in the target behavior.
- Reinforcement is delivered, increasing the likelihood the behavior will occur again.
- An S-delta (incorrect stimulus) is presented.
- If the learner responds incorrectly, reinforcement is not provided.
Over time, the learner responds accurately only in the presence of the correct stimulus.
Example: Teaching Color Discrimination
SD: A red car is shown, and the instructor asks, “What color is this?”
Correct Response: The learner says, “Red.”
Reinforcement: The instructor provides praise or a preferred item.
S-delta: A green car is shown.
If the learner says “Red,” reinforcement is not provided.
With practice, the learner says “Red” only when a red object is present and not when other colors appear. This process strengthens accurate responding in everyday situations.
Key Components of Discrimination Training
1. Discriminative Stimulus (SD)
A discriminative stimulus (SD) signals that reinforcement is available if the correct behavior occurs.
Examples of SDs:
- A teacher saying, “Raise your hand,” signals that speaking will be reinforced after hand-raising.
- A green traffic light signals that driving forward is appropriate.
- The sound of a can opener signals food availability for a dog.
The SD sets the occasion for a specific behavior by indicating that reinforcement is possible.
2. S-Delta
An S-delta signals that reinforcement is not available for a particular response.
Examples of S-deltas:
- A child calls out in class without raising their hand and receives no attention.
- A vending machine labeled “Out of Order” signals that inserting money will not produce a snack.
- A dog barks at a stranger but receives no attention.
S-deltas help learners understand when not to respond, strengthening discrimination skills.
Stimulus Control and Transfer Procedures
What Is Stimulus Control?
Stimulus control occurs when a behavior happens only in the presence of the correct SD and not in the presence of S-deltas.
A behavior is under stimulus control when:
- The learner responds to the correct SD
- The learner does not respond when the SD is absent
Example:
A child says “Mom” only when their mother enters the room, not when their father does.
Transferring Stimulus Control
Sometimes stimulus control needs to be transferred to a new cue so the skill can generalize.
Steps for stimulus control transfer:
- Use prompts (verbal, gestural, or physical) to guide the response.
- Gradually fade prompts.
- Reinforce independent, correct responses.
- Practice across settings to promote generalization.
Example: Teaching “Sit” to a Dog
- The trainer says “Sit” while giving a hand signal.
- Over time, the hand signal is faded.
- The dog sits when hearing the verbal cue alone.
Stimulus Discrimination vs. Stimulus Generalization
Stimulus discrimination occurs when a learner responds differently to similar stimuli based on reinforcement history.
Example:
A child says “Red” only when seeing a red car, not an orange or green one.
Discrimination allows learners to make accurate and precise responses.
Stimulus Generalization
Stimulus generalization occurs when a learner applies a skill to new but similar stimuli.
Example:
A child learns the word “Dog” after seeing a Labrador and later labels a Golden Retriever as “Dog.”
Both discrimination and generalization are important. Discrimination ensures accuracy, while generalization allows flexibility across environments.
How to Implement Discrimination Training Effectively
Start With Clear SDs and S-Deltas
Make stimuli easy to tell apart at first.
Example:
- Present an apple (SD) and reinforce “Apple.”
- Present a banana (S-delta) and do not reinforce “Apple.”
Reinforce Correct Responses Immediately
Deliver praise, tokens, or preferred items right after correct responses to strengthen learning.
Use Prompts and Fade Them Gradually
If a learner struggles:
- Use verbal, gestural, or physical prompts
- Fade prompts slowly to build independence
Mix in Mastered Skills
Interleave mastered tasks with new ones to maintain motivation and retention.
Ensure Generalization
- Use different examples (various shades of red)
- Teach in multiple environments
- Rotate instructors when possible
Final Thoughts
Discrimination training is essential for helping learners respond accurately to their environment. By using SDs, S-deltas, reinforcement, and stimulus control strategies, learners develop skills that support independence, communication, and adaptive behavior.
Key Takeaways
- SDs signal when reinforcement is available
- S-deltas signal when reinforcement is not available
- Stimulus control ensures accurate responding
- Discrimination builds precision
- Generalization promotes flexibility
When implemented consistently and thoughtfully, discrimination training helps learners succeed across settings and situations.