Final answer:
Unlearned response generalization occurs when an organism responds to stimuli similar to the conditioned stimulus in the same way it responds to the conditioned stimulus. An example of this is a dog salivating to a similar sound after being conditioned to salivate to the sound of a bell.
Step-by-step explanation:
In classical conditioning, unlearned response generalization due to physical similarity of responses refers to an organism demonstrating a conditioned response to stimuli that are similar to the conditioned stimulus.
When an organism responds to similar stimuli in the same way it responds to the conditioned stimulus, it is called stimulus generalization. For example, if a dog has been conditioned to salivate to the sound of a bell, it may also salivate to a similar sound, such as a doorbell or a phone ringing.