. The amount of saliva that the dog excreted while eating was measured in a container. The normal reflex of the brain is the salivation of food. But Pavlov noticed that the dog's saliva had begun to drip from the food, not from the food. Pavlov saw the food and measured the amount of saliva in the container. After several days, Pavlov saw the dog's saliva coming out as soon as he entered the lab. Stay with food and don't stay. This time Pavlov did not go to the lab himself but sent his lab assistant to the lab without food. The lab assistant was surprised to see him and (the lab assistant) saw the dog salivating. Pavlov did something different this time. He continued to ring a bell at the same time as he was feeding the dog. Meals are being served and bells are being rung. Then Pavlov and the assistant came to the lab one day without food and started ringing the bell.