Final answer:
Mary is using the principle of positive reinforcement by adding the desirable stimulus of praise to increase desired behavior in her classroom.
Step-by-step explanation:
Mary, a teacher who likes to use lots of praise in her classroom, is utilizing the principle of positive reinforcement. This technique involves adding a desirable stimulus—in this case, praise—to increase a behavior. Positive reinforcement is known as an effective way to teach new behaviors by rewarding actions we want to see more frequently. For instance, when students participate actively or show improvements, and they receive praise from Mary, this reinforces that behavior and makes it more likely they will continue doing so in the future. Unlike punishment, which aims to decrease behavior, positive reinforcement aims to increase desired behavior by adding something pleasant in response to that behavior. Mary's use of praise is a form of a secondary reinforcer, as it's a socially conditioned reinforcer that can augment the likelihood of desired behaviors being repeated.