What is a discriminative stimulus (Sd) in DTT?

A discriminative stimulus (Sd) in Discrete Trial Training (DTT) is defined as a stimulus that evokes a specific response from an individual. It serves as a cue or signal that indicates the presence of reinforcement contingent upon the performance of a behavior. For example, when a teacher asks a student a question or presents a task, that specific prompt acts as the discriminative stimulus, which leads the student to respond in hopes of receiving positive reinforcement for their correct action.

The other options refer to stimuli with different functions. A stimulus that prevents a response would not encourage behavior and thus does not qualify as a discriminative stimulus. Stimuli providing negative reinforcement or signalling punishment also do not fit the role of a discriminative stimulus since they involve different types of consequences that are not directly related to evoking a desired response. Understanding these distinctions is essential in applying DTT effectively in behavioral interventions.