"Hands-free is fine"

The law says you can, and the belief follows naturally. The problem with a phone in the car must be the hand off the wheel and the eyes off the road, so a phone in a cradle, on speaker, or through the car's own system has solved it. Your hands are on the wheel. Your eyes are ahead. What's left?

Attention is what's left, and it's the part that was doing the driving. In 2001 Strayer and Johnston had people drive a simulator while doing various things. Listening to the radio didn't hurt their driving. Listening to a book didn't. Repeating words back on a handheld phone didn't, which rules out holding, listening and speaking as the problem. What hurt was conversation. An ordinary conversation, on either a handheld or a hands-free phone, doubled the number of simulated traffic signals drivers failed to notice and slowed their reactions to the ones they did. Two years later Strayer, Frank Drews and William Johnston showed why. Drivers on a hands-free call were worse at reacting to the car in front braking, and afterwards they couldn't recognise roadside billboards they'd looked straight at. The eye tracking showed their eyes had been on the billboards. The attention hadn't. The authors called it inattention blindness, and it means looking without seeing.

The crash figures say the same thing. Redelmeier and Tibshirani's drivers, from the last chapter, showed no safety advantage for hands-free units, and the point estimate was actually higher. Suzanne McEvoy and colleagues did a similar study in Perth with four hundred and fifty-six drivers who'd ended up in hospital after a crash, using phone company records, and found phone use in the ten minutes before a crash was associated with about four times the risk. Hands-free was 3.8, handheld 4.9, and the difference wasn't significant. Their last sentence was that using a hands-free phone is not any safer.

Two meta-analyses pull the experiments together. William Horrey and Christopher Wickens combined twenty-three studies and found the cost fell mostly on reaction time, and that hands-free and handheld showed the same pattern. Jeff Caird and colleagues combined thirty-three, about two thousand participants, and put the average slowing at a quarter of a second, the same for both phone types. They also found that drivers on the phone didn't compensate by slowing down or leaving more room. Yoko Ishigami and Raymond Klein reviewed the two types directly and found hands-free was rarely better, and that some drivers compensated for a handheld phone and forgot to for a hands-free one, because it felt safe.

So the law permits hands-free, and that's a fact about the law. The law draws its line where a police officer can see it, at the hand. The attention research draws it somewhere else. I'm not telling you that a hands-free call is illegal or that you can never take one. I'm telling you the belief that it's fine is the belief the evidence is least kind to.