Answer:
higher-order conditioning
Explanation:
Pavlov found that a conditioned stimulus with a neutral (unconditioned stimulus ) associated, the dogs will experience the same previous salivation. First food was provided at the same time a bell ring, then the removal of the food, which was a natural trigger to making the dogs salivate was not present, still when ringing the bell, the dogs would act as if they were in front of the food.
This also called Higher Order Conditioning was the cornerstone of Pavlov findings.
The image shows the experiment:
