Phobia:Phobia is an extreme and irrational fear of a specific object or situation. For example, someone with cynophobia has an intense phobia of dogs.
Classical Conditioning:Classical conditioning is when we learn to associate two stimuli together through repeated pairing. In John's case, his fear of all dogs may have been learned through classical conditioning if he associated the pain from being bitten with all dogs.
Generalization:Generalization occurs when we respond to similar stimuli in the same way we would respond to the original stimulus. In this case, John's fear of all dogs can be seen as generalizing his fear from one dog bite to all dogs.