Keeping your eyes on the road may not be enough to keep you from avoiding an accident.

Using your cellphone behind the wheel has the same effects as having a blood alcohol content of 0.8 -- the legal limit for drunk driving. Switching to a hands-free device lessens your chances of getting into an accident, but not by much. That's because it isn't what you're doing with your hands that counts. It's what's going on in your head.

New research shows that just thinking about receiving a call or a text message is enough to raise the risk of a crash. In a study by Jennifer Whitehill, a postdoc at the University of Washington, undergraduate students were asked to take a standardized survey indicating their level of cell phone attachment. When cross-referenced with the participants' driving records, the researchers noticed a relationship between attachment to mobile devices and accidents involving motor vehicles.

Whitehill and Beth Ebel, an associate professor of pediatrics at the University of Washington and the paper's senior author, administered the survey, which has been used in the past to study other types of addiction, to 384 psychology students and tracked them for three years. Among those who scored well enough on the survey to land in the bottom quartile -- that is to say, the least attached to their phones -- researchers counted about 25 car crashes per 100 people per year. But among those who scored in the top quarter for cell phone addiction, that figure jumped to 38 crashes per 100 people per year. In other words, there is evidence for a link between cellphone attachment and car accidents.

One way to interpret the data is that simply expecting something to happen on your phone raises your risk of having a crash. It doesn't have to be a specific call or message, said Ebel in a phone interview. Just feeling compelled to check is enough.

Another way to read the study is that the kinds of people who participated in the research are more likely to get into car accidents. Such a reading would confirm what we've already learned about crashes: that younger people with less driving experience are at a higher risk for them.

The study is being released just as the Department of Transportation is renewing its push against distracted driving. At a conference in San Antonio last week, Transportation Secretary Ray LaHood called for a federal ban on talking or texting on a phone while on the road.

"It used to be that if an officer pulled you over for drunk driving, he would pat you on the back, maybe call you a cab or take you home, but he wouldn't arrest you," LaHood said. "Now that has changed, and the same enforcement can work for people who talk on cell phones while driving."

If Whitehill's research is right, LaHood might want to temper his hopes. You can put your phone away, or even turn it off, but it's not clear what, if anything, can be done in the moment about your thoughts. In some ways, we're faced with a don't-think-about-pink-elephants kind of situation where the act of ignoring your phone inevitably causes you to think about it even more. Short of a cultural shift in which cell phone use declines -- and along with it, the associated need to be reachable around the clock -- distracted driving is likely to stick with us for the foreseeable future. At least until self-driving cars become a reality, that is.