Final answer:
The owner using their body as a barrier to prevent their dog from jumping on people is a form of behavior modification, teaching the dog that this action is unacceptable.
Step-by-step explanation:
When an owner walks between their dog and people to prevent the dog from jumping on them, this is a behavior modification technique. It is similar to when a dog is scolded for jumping on a sofa, it may learn to avoid this behavior. Similarly, an owner actively preventing a dog from jumping on people is using a physical boundary to teach the dog that this behavior is unacceptable. This type of intervention can be effective over time as the dog associates the owner's presence as a barrier to the unwanted action of jumping on people.