What is a Discriminative Stimulus?
A discriminative stimulus (often shortened to “SD”) is a cue that tells someone a certain behavior will be rewarded. When the SD appears, it signals that doing the right action now will lead to something good.
Example
Imagine a traffic light:
- A green light tells a driver, “Go ahead—if you press the gas pedal now, you’ll get where you want safely.”
This green light is acting like an SD—it signals that driving now will lead to a positive result.
How It Works
- Learning through practice
People learn which cues (like a green light or a teacher’s instruction) mean they should do a certain behavior to get something good. Over time, they learn to respond when they see that cue . - Cues can be many things
- Sometimes it’s a spoken instruction: “Please say ‘hello’.”
- Other times it’s a non-verbal sign, like a light turning on or a picture card.
All of these are types of SDs—they tell the person reinforcement is available.
Why Is It Important?
- Works like a signal: The SD guides behavior, letting the person know when doing something is likely to be rewarded.
- Helps in learning: By responding to the SDs, the learner knows when to perform a skill correctly and gets practice learning skills over time.
How to Use in ABA Therapy
ABA (Applied Behavior Analysis) therapists use SDs all the time:
- Before asking a client to do something, they give the SD (e.g., “Touch the red card.”)
- When the client responds correctly, they provide reinforcement like praise or a reward.
This pattern helps the learner connect the SD, the correct response, and the reward—and learn new skills.
Key Points
- SD = cue or signal that tells the learner reinforcement is available.
- The right behavior is more likely to happen only when the SD is present.
- SDs help learners understand when to respond, which makes learning efficient.
Simple Summary
Discriminative Stimulus (SD) = a sign or cue (like a green light or instruction) that tells someone, “Do this now, and you’ll get something good.”
