After decades of marriage, Terry and Debbie Buchen learned to work through various marital issues. Then something new came between them -- his cell phone. Mr. Buchen, 62, couldn't put it down while driving. The first time he sent e-mail messages from behind the wheel, he drove his BMW SUV into a ditch on a deserted stretch of road. He was alone and driving slowly, and he wasn't injured. Still, the incident was 'very scary,' his wife said. Mr. Buchen knew he had a to make a choice between his habit and marital bliss. 'I chose my wife,' he said. But then Mr. Buchen, an agronomist for golf courses, asked for a compromise: he asked her to drive when they were together so he could stay connected with clients. That didn't fly. 'If looks could kill,' he said. For all the conversations about distracted driving playing out in statehouses and on talk shows, the most heated discussions, and the ones with the most lasting impact, may be happening between family members and friends. Such disputes are an extension of a longstanding source of tension -- sometimes light, other times more antagonistic -- between drivers and their self-appointed watchdogs. It's just that now, the backseat driver is going after the BlackBerry. These critics say such devices not only put lives at risk, but also steal attention from passengers hoping for some quality catch-up time. The multitaskers counter that, in their view, social and work demands override the increased crash risks. Safety advocates who favor outlawing multitasking behind the wheel say the new generation of backseat hawks may be playing a crucial role in changing the culture -- much as they did in helping enforce seatbelt laws -- in a way these advocates say laws alone may not be able to. In a survey conducted earlier this year of 2,501 people, the AAA Foundation for Highway Safety found that 48 percent of people worry about a friend or family member driving unsafely. Of those people, 19 percent said the cause of their concern was multitasking behind the wheel. Some drivers say that the second-guessing is unnecessary because of their ability to handle driving and other tasks. 'I barely even look at my phone when I text,' said Sarah Edwards, 29, a customer service representative in Cleveland. Her close friend, Amy Macauley, 32, isn't convinced. 'We've talked about this,' Macauley said. 'I've cited vague statistics about how dangerous it is, but she doesn't pay attention.' She brings a particular sensitivity to the discussion. Her sister and the husband of a close friend died from crash injuries, and her brother-in-law was seriously injured in a car accident. 'I know things can change in an instant when someone is behind the wheel,' Macauley said. To her, talking on the phone or texting while driving, unless it's an emergency, is 'completely gross.' People like Macauley are finding more ammunition to argue their side. Studies show that people who talk on the phone while driving face four times as great a crash risk as those who do not. The risk is considerably higher for motorists who text. The federal government estimates that at any given time about 11 percent of drivers, or about 2 million people, are talking on a cell phone. Many of them are likely doing so alone. Up to 85 percent of drivers have no passenger with them in the car, estimates the Virginia Tech Transportation Institute. But when an adult passenger is present, the Transportation Institute found, he or she can enhance safety -- and reduce crash risk by up to 50 percent -- perhaps by acting as a second set of eyes on the road, or encouraging safer behavior. That means that a friend or family member cajoling a motorist to put down the phone can provide a safety advantage, as long as the disagreement itself doesn't escalate to the point where it becomes its own distraction. 'An emotional, heated argument probably isn't good, but that's just my opinion,' said Charlie Klauer, senior research associate at the Transportation Institute. For all the evidence about the dangers of distracted driving, multitaskers say there are powerful forces -- both social and economic -- that make it hard to put their devices down. A 2008 poll taken by Nationwide Insurance of 1,500 motorists found that 48 percent of people who multitask behind the wheel do so because they feel an urgent need to address an issue pertaining to school or work; 33 percent said they felt pressure to stay connected socially. That lure may entice some people more than others. An emerging body of science suggests that there are some people who are more likely to be drawn to multitasking -- behind the wheel or otherwise -- because of the way their brains are wired. Clifford Nass, a co-director of an automotive research laboratory at Stanford University, said some researchers have labeled such heavy multitaskers as 'explorers' because they enjoy the constant hunt for information -- whether it pertains to work, entertainment or social life. Vic Gideon, 48, a hospital executive from Cleveland, says he feels the call of his device for social and work purposes, even when behind the wheel and even when his family, including his four children, are in the car. 'Even if I'm going 60 miles an hour, I feel the need to check it,' said Gideon, referring to his phone. 'It might be spam, a wrong number, whatever. But who cares? My cell vibrates. I respond.' Gideon said it had created tension. 'My wife tells me I don't know how to drive,' he said. 'And then, of course, not only do I not know how to drive, but I don't know how to drive safely. I believe I'm being careful.' The Nationwide Insurance poll found that both men and women are avid multitaskers. About 85 percent of female drivers said they multitasked, compared with 78 percent of male drivers. Grace Andrews, 49, a corporate consultant in Melrose, Mass., is the one taking heat in her family. Her husband, Joe Nardone, 44, and her son, Colby Andrews, 12, despise her incessant use of the phone, which she concedes can be over-the-top. 'I honestly do laugh at myself all the time,' says Andrews. 'Is it really possible that I am talking on the phone, e-mailing and driving with my knees simultaneously?' Her husband and son tell her that she cares more about the phone than she cares about them, and that she's putting herself and others at risk. 'I could never imagine that we would get to this stage -- that this is the stuff we would fight about,' she said. 