bubba, a very smart german shepherd, has learned that if he barks at the neighbors while they are grilling, they will throw him a candy. however, his owner, paul, does not want bubba to eat candies as it is not good for his health. he does not allow bubba to eat candies from the neighbors. when paul is in the yard, bubba never barks at the neighbors. in operant conditioning terminology, bubba is demonstrating that he can