Answer:
A conditioned stimulus from one learning trial is used in place of an unconditioned stimulus in a new conditioning trial, where it is paired with a second stimulus. The second stimulus then comes to elicit the conditioned response, even though it has never been directly paired with the unconditioned stimulus. This is a description of a procedure called: Higher Order Conditioning.
Step-by-step explanation:
This is a type of conditioning developed by Ivan Pavlov in the 19th Century during physiological investigations. The results of these studies have shown that the conditioning happens when pairing a stimulus to something that has been condition priorly to produce a response rather than to something that would produce a response naturally.
Pavlov experimented with dogs using bells and objets.
Bells represented a conditioned stimulus, while objets represented a neutral stimulus (this is because in a prior experiment called Classical Conditioning he had already used bells and the dogs had already been able to recognize bells as a stimulus before.)
In this type of conditioning, Pavlov used a steak and a bell instead of using a random object. When he showed the steak to the dogs, as it was naturally expected, they salivated. Then he resolved to experiment by ringing a bell at the same time he was showing the steak to the dogs, wondering if when the bell rang at the view of the steak the dogs would still salivate, which was exactly what happened. At that moment he realized he had created a conditioned stimulus on his experiments through the use of bells.
Later on, when experimenting through the effects of the Higher Order Conditioning, Pavlov found out that when the bell (conditioned stimulus) was rang (which was the way in which he ordered the dogs to stop salivating) and he decided to introduce a random object (neutral stimulus), the dogs still continued to salivate, and even if he took the bell away and the random object was used instead of the bell, the dogs would still continue to salivate. Upon this facts, Pavlov discovered that even if the stimulus was changed, salivation would still happen.
I hope it helps!