Members of the generation that grew up with mobile devices are less likely to speak up if they’re in the car with a driver who is busy texting or talking on one, according to a federal survey released Monday.

The National Highway Traffic Safety Administration’s survey of 6,000 people found that almost 90 percent said they considered a driver who was sending or reading text messages very unsafe. But the number who said they would say something to the texting driver varied by age, with younger passengers less likely to be outspoken.

When it came to talking on a cellphone, about a third of adults under the age of 24 said they might speak out, while half of those 65 and older said they would.

NHTSA statistics indicate that drivers ages 18 to 20 years old have the highest level of phone involvement in crash or near-crash incidences. They are nearly three times as likely to report they were reading or sending a text or e-mail when such an incident occurred as compared to drivers age 25 and older. In addition, drivers younger than 25 are two to three times more likely to drive while sending or reading a text message or e-mail. Reports of texting while driving drop sharply as age increases, NHTSA said.