text: 9 percent of all teenagers expect to receive a reply to a sent text message within five minutes. Brake reaction speed can be slowed by up to 18 percent when someone is texting while driving. Holding a phone in one hand while navigating a vehicle slows reaction time by 46 percent. Texting while driving is more of a problem now than ever, as 69 percent of U.S. drivers between the ages of 18 and 64 admitted to using their cell phone while driving during the previous month.                        Dear. State Senator