Todd is walking down main street and sees a sign reading 'Hot & Fresh Donuts.' In the past, that sign has typically correlated with an increased availability of donuts. What type of antecedent is the sign?

• A. An MO
• B. An SD
• C. Positive Reinforcement
• D. Response Reinforcer

Answer: (B)

Discriminative stimulus signals that reinforcement is available. The sign “Hot & Fresh Donuts” has been paired with a history where showing that sign leads to donuts being obtainable. When Todd sees it, it occasions the donut-seeking behavior because past contingencies showed that this cue predicts the availability of the reward. It’s not changing how much donuts are valued right now (that would be a motivating operation), and it isn’t the reinforcement or a consequence itself—it's an antecedent cue that sets the occasion for the response to produce reinforcement.