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.

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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.

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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.

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