Definition
Discriminative Stimulus (SD) is an antecedent stimulus that signals the availability of reinforcement for a specific behavior. When a behavior occurs in the presence of the SD, it is more likely to be reinforced, giving the stimulus control over the behavior. The SD sets the occasion for the behavior by indicating that a particular response will be followed by reinforcement.
Example
In a classroom, the teacher says, “It’s time to raise your hand if you have a question.” This statement acts as a discriminative stimulus (SD) because it signals to the students that raising their hand will be followed by the teacher calling on them (reinforcement). When the teacher is not giving this cue, raising a hand may not result in the same reinforcement, so the behavior of raising the hand is more likely to occur when the SD is present.