They sell clicker noise makers for dogs using this very approach. I have watched dogs as puppies grow up hearing this clicker and will automatically come running. However, I found that dogs that are in bred from a puppy mill have a learning disorder and no matter what you do, they just cannot grasp the concept, not just with the classic conditioning, but in most things such as walking, healing, etc. I studied this concept in my Psych 101 class at University. Thanks