Answer:
Shaping
Step-by-step explanation:
Shaping: In psychology, the term "shaping" is described as one of the different behavioral modification techniques. It involves a particular process of successive reinforcement in order to get closer and closer "approximations" related to a desired and required behavior.
Shaping is considered as a "conditioning process or paradigm" that is being widely used by the experimenters in the "experimental analysis of behavior.
In the question above, Johnny was taught to play quietly for extended periods through shaping.