HOUSTON, TX (CBS) – With plenty of PSAs and warnings about texting while driving, you’d think the American public would start to get the message.

But a new study reveals that drivers under 25-years-old were 4.12 times more likely to use their cell phones while driving.

The study, which is published in Preventative Medicine Reports, was conducted by University of Texas Health students and faculty and used data from 2011-2013 provided by students enrolled in an epidemiology course on field research methods.

Those students watched drivers who’d stopped at a number of intersections and recorded their cell phone use, seat belt use, the presence of passenger and both driver and vehicle characteristics.

Interestingly, younger adults weren’t the only ones on their phones. Women were 1.63 times more likely to use a smartphone while driving, and unaccompanied drivers were also more likely to be on their phones.

What’s more, the study claims texting while driving actually increased 2 percent from 2011 to 2013.

“Drivers distracted by cell phones pose a safety threat to pedestrians and motorists in these areas,” said R. Sue Day, Ph.D., an associate professor in the Department of Epidemiology, Human Genetics & Environmental Sciences, on the school’s website.

Researchers also say that public safety campaigns might want to focus more on women and younger drivers.