Hang up and keep your mind on the road?

Oct. 18, 2015

The riskiness of talking while driving is getting renewed attention in Massachusetts as the state legislature considers allowing only hands-free cellphone use. (Massachusetts drivers over 18 may now use handheld cellphones but may not text while behind the wheel.) Currently, 14 states ban the use of handheld devices while driving; another four have instituted partial bans (see map).

David Ropeik, an instructor at Harvard and author of How Risky Is It, Really? Why Our Fears Don’t Always Match the Facts, opposes hands-free cellphone use by drivers. In The Boston Globe, he writes, “Talking on a mobile phone distracts your brain from whatever else you’re doing. Driving? Walking down the street? Doesn’t matter. Your attention is on the conversation, not on the task at hand. What your hand is doing is irrelevant. The conversation distracts your brain.”

He cites simulation studies by David Strayer and colleagues at the University of Utah, showing these levels of distraction, vs. a baseline of 1 for people simply driving:

  • listening to the radio, 1.21;
  • listening to a book-on-tape, 1.75;
  • talking on a hands-free cellphone, 2.27
  • talking to a front-seat passenger, 2.33;
  • talking on a handheld cellphone, 2.45; and
  • interacting with a speech-recognition email or test system, 3.06.

The simulations in Strayer and colleagues’ studies involved subjects in a test car following a pace car that brakes at random intervals. Parameters measured included the subjects’ brake reaction times, following distances, and the probability that the subjects would glance at a hazard outside their simulated vehicle.

A glance at the distraction levels shows that talking on a hands-free devices is less distracting than conversing with a front-seat passenger. It’s unlikely that states would try to ban talking with vehicle passengers.

However, writes Ropeik in the Globe, the real problem with a proposed Massachusetts law allowing hands-free cellphone use is psychological: “It sounds like hands-free is safer. That sends a dangerous message to our emotionally-based psychological risk-assessment system. Anyone using a hands-free device will think, ‘I have done something to reduce my risk, to take control.’ A feeling of control over a risk makes it less scary. So people using hands-free devices will be just as distracted, but because they think they’re safer, many of them are likely to be less careful when driving and using a phone.”

As Strayer and his colleagues put it in their paper, “Increasingly, car manufacturers and third-party providers are presenting consumers with options to make movie or dinner reservations, send and receive text or e-mail messages, make postings on Facebook, interact with global position systems, and utilize voice commands for controlling functions of the vehicle. The lessons learned from the current research suggest that such voice-based interaction is not risk-free, and in some instances the impairments to driving may rise to the level associated with drunk driving…. Just because a new technology does not take the eyes off the road does not make it safe to be used while the vehicle is in motion.”

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