Which situation is most indicative of a discriminative stimulus?

The situation where a child consistently receives praise for effort is the most indicative of a discriminative stimulus because it highlights the role of an antecedent that signals the availability of reinforcement. In this case, the praise serves as a cue that reinforces a specific behavior—showing effort—which increases the likelihood that the child will engage in that behavior again in the future when in similar contexts.

Discriminative stimuli are key elements in operant conditioning, as they provide information about the conditions under which a behavior will be reinforced. The consistent praise acts as a signal that certain behaviors (like effort) will result in a positive outcome (praise), thus encouraging the child to repeat those behaviors when similar stimuli are present.

In contrast, other situations such as ignoring a behavior or effectively punishing it do not emphasize the presence of a signal that increases the likelihood of future behavior. Changes in environment that lead to fluctuations in behavior may suggest variability but do not clearly indicate the presence of a discriminative stimulus since they lack the reinforcement component that praises provides.