Your friend peter has trained his dog to salivate every time peter rings a bell, since the dog associates getting to eat when he hears the bell. peter then decides to pair a light with the bell, then eventually removing the bell. now his dog salivates when he only sees the light. peter has just succeeded at a procedure known as:
Peter had succeeded at the procedure known as the higher
order conditioning. This is present in classical conditioning in which the
stimulus is being used for having to form a new stimulus by having to learn
from the previous stimulus.