Final answer:
Mr. Tower is changing the antecedent of Tyrone's behavior by tapping his shoulder, as the antecedent is what occurs before a behavior and can influence its occurrence.
Step-by-step explanation:
If Mr. Tower decided to tap Tyrone on the shoulder when his head is down, instead of ignoring his behavior, Mr. Tower is changing the antecedent of the behavior. In behavioral psychology, an antecedent is something that occurs before the behavior and can influence its occurrence. By tapping Tyrone on the shoulder, Mr. Tower is creating a new antecedent that could potentially alter Tyrone's response, thus modifying the stimuli or environmental condition that leads up to the behavior.