In the nose example, the student's imitation was triggered by which concept?

• A. Generalization
• B. Discrimination
• C. S-delta signaling extinction
• D. Formal similarity

Answer: (D)

Imitation is driven by the form of the modeled response matching the learner’s response, what behavior analysts call formal similarity. In the nose example, the student copied an action that shared the same topography as what was shown (for instance, touching or pointing to the nose in the same way). That topographic match makes the imitation more likely to occur because the learner is responding in a way that directly resembles the model’s action, reinforcing the imitation pathway.

Generalization would involve extending a response to new but related stimuli or contexts, not the specific imitative match to the model. Discrimination focuses on distinguishing between stimuli and responding differently, which doesn’t explain why the exact modeled action is copied. S-delta signaling extinction relates to cues that signal non-reinforcement, not to the listener mirroring a modeled behavior. So the trigger in this nose scenario is the formal similarity between the modeled action and the learner’s imitated action.