Answer:
The answer is stimulus generalization.
Explanation:
Stimulus generalization is a concept used both in operant and in classical conditioning; it refers to the process in which a similar stimulus can provoke the same conditioned response. For example, if a person is afraid of spiders he or she might experience the same response of fear when seeing other insects similar to spiders, or when seeing pictures of spiders.
In this case, Thor has generalized the command to other objects that are similar to the ball he learned to fetch.
