Final answer:
The trainer's advice constitutes negative punishment, as it involves removing a desirable stimulus (playtime) to decrease undesirable behavior (biting) in the puppy.
Step-by-step explanation:
The trainer's recommendation to the owner of a puppy that is play biting involves yelping loudly and discontinuing play whenever the puppy bites. This is an example of negative punishment. The rationale behind this is that the desirable stimulus (playtime) is being removed to decrease the unwanted behavior (biting), which fits the definition of negative punishment. Unlike positive punishment, which adds an unpleasant stimulus to reduce a behavior, or positive reinforcement and negative reinforcement which both serve to increase behavior, negative punishment involves taking away something valued to reduce the frequency of an undesired behavior, which aligns with the scenario presented.