Essential Reading
The below conversation between an RBT and their BCBA supervisor discusses the concept of stimulus and talks about stimulus classes:
RBT: Hi, I’ve been hearing about discriminative stimuli and stimulus classes in ABA. Can you explain the difference?
BCBA: Of course. In ABA, a stimulus is any event or situation that can be perceived by our senses, like something we see, hear, touch, smell, or taste. It plays a role in behavior change. Now, within stimuli, we have two important categories: discriminative stimuli and stimulus classes.
RBT: So, what’s a discriminative stimulus?
BCBA: Good question. A discriminative stimulus (SD) is a specific type of stimulus. It’s like a cue that tells the individual that if they perform a particular behavior in its presence, they’ll get reinforcement. It signals that a certain response will lead to a reward. For example, when a teacher says, “Raise your hand if you know the answer,” the teacher’s voice is the SD that signals reinforcement (like praise) for raising one’s hand.
RBT: Got it. What about a stimulus class?
BCBA: A stimulus class is a broader concept. It’s a group of stimuli that share similar characteristics and can evoke the same or similar responses. These stimuli might not look or sound the same, but they have common features that make them functionally equivalent in terms of their effects on behavior.
RBT: Can you give an example to clarify the difference?
BCBA: Absolutely. Let’s say we’re teaching a child to touch a red square when we say, “Touch red.” In this case:
The stimulus is the red square.
The discriminative stimulus (SD) is the teacher’s instruction, “Touch red.”
The stimulus class includes all red objects (like a red circle, red triangle, or red star) because they share the common characteristic of being red. So, if we say, “Touch red,” the child could touch any red object in that class, and it would be a correct response.
RBT: I see, so understanding the difference helps us in teaching and generalizing behavior across similar stimuli, right?
BCBA: Exactly! Recognizing discriminative stimuli and stimulus classes helps us design effective interventions, promote the generalization of skills, and modify behavior more efficiently. It’s a crucial concept in ABA practice. If you have more questions or need further clarification, feel free to ask.
This article from Learning Behavior Analysis summarizes the difference between a stimulus and a stimulus class.
Learning Behavior Analysis. (n.d.). B-2: Define and provide examples of stimulus and stimulus class ?. Retrieved March 24, 2022, from https://learningbehavioranalysis.com/b-2-stimulus/
Optional Video
de Aguiar-Rocha, L. (2016, May 12). Stimulus class [Video]. You Tube. https://www.youtube.com/watch?v=N368AZ1V5do
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