B.2: Identify and distinguish between stimulus and stimulus class.
Free practice questions for this part of the BCBA, with an explanation for every option.
A learner says "apple" when shown a red apple, a green apple, apple slices, and a cartoon drawing of an apple. These stimuli share physical features such as shape and color patterns. They are best described as:
- A. A response classIncorrect. A response class groups behaviors. This item is about a group of antecedent stimuli.
- B. A set of conditioned stimuli produced by respondent pairingIncorrect. Saying "apple" is an operant under discriminative control, not a respondent elicited by a conditioned stimulus.
- C. A feature stimulus classCorrect. Stimuli that share common physical features and occasion the same response form a feature stimulus class.
- D. An arbitrary stimulus classIncorrect. Members of an arbitrary stimulus class share no physical features (e.g., the printed word APPLE and the real fruit). These stimuli do share features.
In a supported employment program, a 34-year-old worker walks to the break room when a wall bell rings, when a light over the door flashes, and when his supervisor says "Break time." These three stimuli look and sound nothing alike, but each reliably occasions the same response. They are best described as:
- A. An arbitrary stimulus classCorrect. An arbitrary stimulus class is a group of stimuli that evoke the same response even though they do not resemble one another physically. Their membership comes from a shared function, not shared form.
- B. A conditioned stimulus for walkingA conditioned stimulus elicits respondent behavior after pairing with an unconditioned stimulus. Walking to the break room is operant behavior that these stimuli occasion.
- C. A feature stimulus classA feature stimulus class is made up of stimuli that share physical features, such as shape or color. A bell, a light, and a spoken phrase share no physical features.
- D. A stimulus generalization gradientA generalization gradient shows how responding changes as stimuli differ more and more along a physical dimension from the trained stimulus. These stimuli do not vary along one shared dimension.
A BCBA is teaching a new RBT the difference between a stimulus and a stimulus class. Which example describes a single stimulus rather than a stimulus class?
- A. All printed words that begin with the letter BThis is a group of stimuli that share a common physical feature (the initial letter B). That makes it a feature (formal) stimulus class.
- B. The beep of the kitchen timer at the moment a session endsCorrect. A stimulus is a specific energy change that affects the person's sense receptors. One beep at one moment is a single stimulus event.
- C. Any adult who greets the child by saying "Good morning"This is a group of different adults and greetings that share a common element. It is a stimulus class, not a single stimulus.
- D. All of the foods that lead a toddler to reach toward themThis is a group of different foods defined by a shared effect on behavior (reaching). It is a functional stimulus class, not a single stimulus.