Question: In the presence of this stimulus, the behavior does not produce reinforcement.
Answer: Stimulus Delta (SΔ).
An SD signals the availability of reinforcement. It’s the stimulus that basically says, “Hey, if you need this specific reinforcement, you can have it if you engage in this needed behavior.” For example, iced coffee is an SD. It says, “Hey, I can get you some delicious, refreshing coffee and caffeination if you pick me up, and put this straw in your mouth, and drink.” An SΔ, on the other hand, does not signal reinforcement. Coffee can also be an SΔ if I’m hungry; it will not fill me up. It’s also important to note that an SΔ, though often referring to signaling zero reinforcement, can also just mean less reinforcement. For example, if I’m dehydrated, both of these drinks can quench my thirst and offer some hydration. But water is more hydrating, so it’s our SD in this scenario. While the coffee choice is the SΔ, which does signal some hydration, it provides less than the water, and actually is even considered dehydrating. Also, keep in mind that everything can be both an SD and an SΔ for different things. I may be an SD for getting some ABA questions answered. But if you wanted advice or help on how to cook or bake something, I’m gonna be an SΔ.