Kathy takes her 2-year-old son to the supermarket every Saturday. Each week, the same sequence of events unfolds: Her son screams, demanding that Kathy buys him treats. Although she refuses to give in to his demands, he continues to scream

Finally, Kathy yells at the top of her lungs, "QUIET!" He stops screaming instantly. What operant conditioning concepts are illustrated in this story?
A) Kathy is using negative reinforcement to increase her son's screaming.
B) Kathy is using punishment to suppress the screaming; her use of punishment is negatively reinforced by the cessation of screaming.
C) Kathy's son probably learned how to scream by observing his parents at home, and now he is reinforced on a variable-interval schedule of reinforcement.
D) Kathy's son probably learned how to scream by observing his parents at home, and now he is reinforced on a fixed-ratio schedule of reinforcement.

Answer: B
Rationale: In this example, Kathy is decreasing her son's behavior (screaming for treats) by presenting a stimulus (yelling); therefore she using positive punishment. At the same time, Kathy's yelling is being negatively reinforced because her yelling is followed by the removal of an aversive stimulus (her son's screaming).