Answer:
Positive reinforcer
Step-by-step explanation:
When a stimulus is followed by a behavior and if the behavior is reinforced then the type of reinforcer used is positive reinforcer. The likely hood of repeating the behavior is increased because of the reinforcer. These are the concepts of operant conditioning.
Here, scolding Mathew results in him losing his temper more.
Hence, the scolding serves as a positive reinforcer.