Discriminative Stimulus (SD)
An environmental stimulus that cues the availability of reinforcement for a specific behaviour.
A Discriminative Stimulus (abbreviated as SD) signals to the learner that if they perform a specific behaviour, reinforcement is currently available. In simple terms, it acts as an environmental green light. A ringing phone is an SD signaling that answering it will be reinforced with a conversation; a silent phone is not.
In teaching and behaviour support, establishing strong SDs ensures that a learner knows when and where to respond. Prompts are temporarily paired with the SD and then faded out so that the natural SD in the environment takes over stimulus control.