Want to drive safely? Talking to passengers may be okay, but talking on the phone isn't

i-eca0cf2af9fc3ac4445c7dff7d8aab70-research.gifMany many studies have repeatedly shown the dangers of driving while using a cell phone. Yesterday, while discussing a new law in Britain imposing heavy penalties not only for driving using a handheld phone, but also while using phones with hands-free kits, commenter Jan claimed that talking to a passenger was less dangerous than talking on a phone. I replied that I hadn't seen a study demonstrating that talking with passengers was any different from talking on a phone, and Jan provided a link to one such study.

Greta and I have both read over the study, and while we can't say from these results that talking with a passenger is unequivocally safer than talking on a phone, the research is impressive. The study comes from David Strayer's laboratory, the same group that has conducted a number of studies demonstrating the danger of driving while talking on the phone.

The researchers, led by Frank Drews, recruited 48 pairs of licensed drivers to participate in a driving / talking task. Drivers were selected randomly, and were paired with people they were friends with outside of the study. Each pair was told to talk about about a "close call" -- a time when their life was threatened -- either on a cell phone or in person, while one of the people drove an eight-mile course on a driving simulator.

The conversation topic was the critical portion of the task, because previous studies comparing conversations with passengers versus on cell phones have found driving ability to be equally impaired. In these tasks, typically the passenger and driver had to complete a difficult task such as thinking of a word that starts with the last letter of the word their partner said, often under competitive circumstances: arguably this is not analogous to a real conversation in a car. The "close calls" topic was chosen because other studies had revealed that it leads to naturalistic conversations.

Drivers were instructed to drive down a busy simulated highway and take the next exit -- a rest area 8 miles away. Half the drivers were told to lead the conversation (tell their own close call story) and half were told to respond to the passenger / cell phone's lead. Every driver also drove the course conversation-free. Here are the results:


Fifty percent of the drivers who were talking on the cell phone missed the exit, while only 13 percent of the drivers talking to the passengers did, a number not significantly different from the control condition with no conversation. What's more, the researchers analyzed the substances of the conversations, and found that in conversations with passengers, the discussion shifted to the traffic / driving situation nearly twice as often than in conversations on the cell phone.

The study appears to be a clear indication that conversations with passengers are safer than conversations on cell phones. Certainly the sort of casual conversation proscribed in this study appears to be less distracting to drivers talking to passengers rather than on phones.

That said, the study has some significant limitations. Arguably, the topic of the conversation -- a life-threatening situation -- is one that primes participants to be looking for danger. I'd be interested to see additional studies with different, more benign conversation topics. Also, since both participants were licensed drivers, these passengers might be more likely to alert drivers to dangers than, say, a child might. The study also doesn't address hands-free cell phone use. Perhaps this is just as safe as conversing with the passenger for this type of conversation. Finally, the study doesn't directly address driving safety, just the ability to complete a driving task.

Despite these limitations, it's the first study I've seen that demonstrates that passengers really do help drivers, and for that, it should be commended. A word of warning: this study is most certainly not an open ticket to gab away in any traffic circumstance. Any distraction will shift attention away from driving and can potentially be dangerous, and this study does nothing to refute earlier claims that the more difficult the conversation topic, the less safe it is for drivers.

Drews, F.A., Pasupathi, M., & Strayer, D.L. (2004). Passenger and cell-phone conversations in simulated driving. Proceedings of the Human Factors and Ergonomics Society, 2210-2212.


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Based on my own internal monitoring of my driving, I think I can tell a difference between talking to a passenger and talking on a cell phone. I can tell a distinct difference between talking on a cell phone with and without a hands-free attachment, but that is mostly because of the physical limitations introduced by having to hold the phone

It would be interesting to see a large study of the effects of talking to passengers and talking on a cell phone while taking into account the driving records of the participants.

There has been, not a study, but a court ruling in Sweden [I lost the url for it]. Surprisingly, it did not condemn use of gsm phones while driving. Instead the ruling tersely concluded that conversations, not the phones is the risk factor while driving.

I suppose the main risk issue here is not even the conversations, but the nature of the conversations. If you have an big argument with somebody while driving, you can hang up a phone more easily than a passenger next to you...

There was a great episode of Mythbusters (episode 33) where they drove on a course, comparing performance sober, on a cell phone, and finally drunk. Intuitively I knew that talking on a cell phone while driving was bad, but the Mythbusters (informal) results showed that was just as bad as driving drunk -- which was surprising.

Uffe makes a great point - we were once hit by a driver whose children in the back seat were jumping up and down and distracting him as they pulled into a library. One of the nice things about cell phones is that you can turn them off if the traffic or the weather (or the difficult conversation) makes it seem like driving and talking would be a bad idea. Kids and noisy passengers on the other hand...

By Teresa Michelsen (not verified) on 24 Jan 2007 #permalink

Of course the passengers help with the driver's concentration, they are likely looking for the same exit as the driver, and so are more "in tune" to helping them. Subconsciously they will adjust to the surroundings, possibly by pointing out the approaching exit signs, giving directions and advice (you can change lanes now), and being quiet if the situation becomes tricky in order to let the driver concentrate on what she is doing.

People on the cell phone likely know that the driver is driving, but are not able to see the traffic and the exit signs, at the least.