Step 1: Understand the scenario.
- Being afraid of {all} animals after a fearful encounter with a {specific} dog suggests generalization.
- Stimulus generalization occurs when a response extends from the original stimulus to other similar stimuli.
Step 2: Analyze the options.
- Extinction: Disappearance of a learned response. (Not applicable here)
- Conditioned response: Specific learned response to a particular stimulus. (Not generalization)
- Secondary learning: Not directly related.
Thus, the correct behavioral phenomenon is: \[ \boxed{{Stimulus generalization}} \]