True or False: An Sd decreases the likelihood that a behavior will occur.

The correct answer to the question regarding whether an Sd (discriminative stimulus) decreases the likelihood that a behavior will occur is that it is false. An Sd actually increases the likelihood of a specific behavior occurring in the presence of that stimulus. The role of a discriminative stimulus is to signal that reinforcement is available for a particular behavior, thus making it more likely that the behavior will be performed when that stimulus is present.

In the context of behavior analysis, the presence of an Sd acts as a cue that indicates to the individual that a response will lead to a positive outcome, such as receiving a reward. Therefore, rather than decreasing the likelihood of a behavior, an Sd enhances the chances that the behavior will be exhibited.

Understanding this concept is essential in applied behavior analysis, as it informs how stimuli can be used to effectively elicit or modify behaviors in therapeutic and educational settings.