Experimental hypothesis: puppies can establish conditioned reflex to ringtones.

1. Let the dog hear the bell, and the dog will not secrete saliva;

2. Feed the dog, the dog will secrete saliva;

3. Ring the bell before feeding the dog;

4. Repeat step 3. After a period of time, dogs will also secrete saliva if they ring the doorbell without feeding.

Experimental conclusion: If the hypothesis holds, the puppy can establish conditioned reflex to the bell.