Answer:
Shaping
Explanation:
In psychology, shaping refers to the process of reinforcing successively closer and closer approximations to a desired terminal behavior.
Shaping has different stages:
As you can see shaping starts by reinforcing any response that resembles the desired terminal behavior and then it finishes by reinforcing only the terminal behavior.
In this example, the therapist initially gave him a piece of chocolate any time he made a sound with his lips. Then he only received a piece of chocolate for saying complete words. Finally, he would get the chocolate for saying complete sentences.
Thus, this is an example of shaping, since the reinforcements where changing as the behavior got closer and closer to the terminal desired behavior.