Effect Measure

Talking to passengers and cell phones

I’m on the road today. I’m a member of an external advisory committee for a research program at a university about an hour by car from my own. Not bad duty. You get to listen to scientists talking about science all day (some of us actually like that) and you get asked your opinions (whether well founded or not). But it’s winter, there’s a storm brewing and the rush hour traffic on the interstate at 7 in the morning is very heavy, cruising along at 60 miles an hour. I’m driving my 14 year old shitbox Volvo sedan with the hood that looks like it will pop up as I drive (it won’t; in fact I’m not sure I can raise the hood). I have a passenger, another academic, an old friend from another institution in the same town as mine and we have a lot to talk about. We’re chatting about something of great interest to us both (academic politics so I won’t trouble you with the details). And I start to notice that I’m not paying enough attention to the road. In fact I’m on total autopilot. And it occurred to me it might not be that different than talking on a cell phone:

You might have heard this advice before, but the National Safety Council has just made it official: They call on motorists to stop using cell phones – even those with hands-free attachments – while driving. They?re also urging state governments to pass laws banning phoning and text messaging while behind the wheel. NSC President and CEO Janet Froetscher had this to say:

Driving drunk is also dangerous and against the law. When our friends have been drinking, we take the car keys away. It?s time to take the cell phone away.

(Liz Borkowski, The Pump Handle)

That got me thinking. What if it were true a passenger is as distracting as a cell phone? Does that mean that if we ban cell phones while driving (which I think is good idea) we should also make people drive solo? Here’s why I think not. Most things in life involve trade-offs and the benefits of increasing the carrying capacity of vehicles is substantial. There is certainly a risk to it as well, since even if talking to a passenger doesn’t cause an accident, a motor vehicle accident where passengers are involved produces more injury (i.e., more injured people on average). But in the larger scheme I feel fairly confident in arguing that having more people in a car (considering energy, air pollution, costs, etc.) on average nets out positively.

When it comes to cell phones, hands on or hands free, I’m not at all confident. In fact I’m guessing it is the other way around. While some phone use in the car may represent a net gain, it seems pretty obvious to me that an awful lot of phoning-while-driving is discretionary visiting. I frequently have people who call me while they are commuting as a way to make the time pass or to “touch base.” I discourage it but it is hard when you don’t want to be rude, so I often wind up talking to them (after telling them I hope they are paying attention to the road).

I’d be just as happy if cell phones were banned when driving. For bona fide emergency use you can explain it to the police.

Do I do it? Almost never (I won’t lie. I’ve done it on occasion for conversations of less than a minute).


  1. #1 Nomen Nescio
    January 16, 2009

    What if it were true a passenger is as distracting as a cell phone?

    if passengers were no more distracting than that, i’d be much happier about chauffeuring my spouse.

  2. #2 Nomen Nescio
    January 16, 2009

    I’d be just as happy if cell phones were banned when driving. For bona fide emergency use you can explain it to the police.

    you mean to say, for bona fide emergency use you can just plain pay the fine you’ll incur. trusting officer discretion not to fine you just because you were having an emergency may well land you with an emergency and a fine.

  3. #3 Casz
    January 16, 2009

    Absolutely, passengers are as distracting as cell phones if you are used to driving alone (kids have got to be the worse!) The study I read indicated it’s not as bad a distraction because the passenger can see and respond to hazards that the driver may not be aware of.

  4. #4 Path Forward
    January 16, 2009

    See Cell phones are more distracting than passengers. It cites an article from the J.Experimental Psychology a month ago, which found:

    Drivers are far more distracted by talking on a cellular phone than by conversing with a passenger in an automobile.

  5. #5 Racter
    January 16, 2009

    My theory has always been that it has to do with the shared visual field (or lack thereof). When talking on the phone, the mind (my mind, anyway) seems to need to create a sort of virtual space in which to “meet” the person, and this apparently requires cognitive resources that would otherwise be used for processing visual input. If the person is sitting right next to me, there’s no need.

    Obviously, if the passenger is a kid, all bets are off.

    I would have looked for theorizing along similar lines in the article Path Forward linked — if the link had worked.

  6. #6 Orac
    January 16, 2009

    There was a story on NPR a while back about this very issue. An investigator had done some rather interesting work on the topic. His take was that the reason cell phones were more distracting than passengers is because passengers are in the car and can see when traffic conditions are getting bad. They actually tend to shut up if they sense the driver needs to pay closer attention. On the phone, there are no such visual cues, and the person on the other end of the phone keeps talking. I’m not sure I entirely buy the explanation, but it is not unreasonable on its face.

  7. #7 catgirl
    January 16, 2009

    I remember a few years ago that someone was trying to use this logic to make it illegal for for teens to drive with other teens in the car. Fortunately, it never went anywhere, at least in my state (PA).

  8. #8 Racter
    January 16, 2009

    Orac has provided a simpler, if somewhat less interesting, explanation. Recalibrating…

    I don’t merely refrain from talking on a cell while driving; I’m also inclined to cut a conversation short once I realize that the person on the other end is doing so. I’d like to avoid being haunted for life by having someone’s last words — “OH SHIT!” — ringing in my ear (accompanied by the sound of crunching sheet metal) and have to deal with the guilt of knowing I might have helped prevent it.

  9. #9 revere
    January 16, 2009

    There are a number of issues here to disentangle. One is whether cell phones are more distracting than passengers. Another whether passengers net out as distracting at all (because, for example, they are an extra pair of eyes). Clearly passengers can be distracting enough to cause an accident (i.e., but for the presence of the passenger there would not have been an accident). I felt noticeably distracted on my drive down today. So starting from that assumption, the post followed.

  10. #10 Science Avenger
    January 16, 2009

    I’d like to compare the risk of cell phone users to people driving over the age of 70, or people joy riding with their kids and/or pets.

    This strikes me as another case of limiting everyone’s freedom because a negligent few can’t handle it, and because of a generational bias of old lawmakers against new young technology. As someone who conducts business via phone from my car constantly, and who has no trouble multitasking (thank you strong feminine side), I object strenuosly to such a law unless the studies show little variance in the level of distraction.

    An additional problem with such laws is it gives the police yet another way to arbitrarily pull anyone over for basically no reason on the grounds that they thought they saw them talking on their cell phone. There is already far too much abuse of police power.

    Finally, its basically unenforceable barring installation of high power scopes in the police cars, since the passenger can easily argue it was really something else in his hand that the cop saw, like my handy dandy portable razor, which I also use in my car. Come on people, is driving really such a challenge?

  11. #11 Michael Zaiser
    January 16, 2009

    The problem is that active scientists should be banned from driving altogether. They are a danger to both themselves and others – since they don’t need mobiles or passengers to get intensely involved in things that mentally distract them from driving. I remember the time when I did my PhD. I was sitting behind the steering wheel of my 2CV. I was just about to solve that integral when a sudden bang put an end to my thoughts, as I had bumped into the car in front who had stopped at a red light. Fortunately it was in town and we were going only at some 15mph. Another time I tried to put the rear drive in at 50 mph while formulating the conclusions section of a paper…

    Sigh, time to get home from my uni office. See you on the road.

  12. #12 Racter
    January 16, 2009

    Science Avenger,
    I’m curious as to how you would rate your own multitasking abilities. Above average? About average? On a similar note, I wonder how often you feel that you would be capable of safely operating your vehicle at somewhat higher than posted speeds?

  13. #13 Orac
    January 16, 2009

    Orac has provided a simpler, if somewhat less interesting, explanation. Recalibrating…

    Actually, now that I think about it, the story was about the science of how humans multitask, and the cell phone issue was just an example of the more general phenomenon. The point of the story was that humans do not multitask nearly as well as they think that they do. They do better with related tasks and worse the less related the tasks are, but in both cases performance takes a significant hit.

  14. #14 Lea
    January 16, 2009

    Oh geez-ohs revere, don’t use your cell phone while driving. Too bad if the one calling is offended.

    Science Avenger: “There is already far too much abuse of police power”. Definitely agree with that one.
    And then “Come on people, is driving really such a challenge?”
    Where I live, yes it is.
    It’s no longer just get in the car and drive. It’s get in the car and drive and then hope like hell that some uncourteous-obnoxious-rude driver doesn’t run into the back of you or run you off the road.

  15. #15 mark
    January 16, 2009

    Interesting posts. One possible difference between conversations with a passenger and talking on a cell phone has to do with how much attention is needed to decipher the words that are being said. I find it quite easy to listen to and understand someone sitting next to me in a car (behind is a bit more difficult), but listening on a cell phone takes much more concentration because the sound quality is not as good. That extra concentration is taken away from the attention I am paying to driving.

    On the issue of cell phone use being prohibited while driving, my personal experience is that when I see someone driving erratically or missing important traffic features (cross-walks, signs, bicyclists), in most cases they are talking on a cell phone. This is not a scientific sample, of course, but I find it strongly suggestive that many people are more dangerous as drivers when they are simultaneously talking on their phones.

  16. #16 stewart
    January 18, 2009

    There’s a fair bit of research out there. Cell phones are distracting, and don’t respond to the environment. Passengers are distracting, sometimes alerting, and do respond to the environment. Age trends indicate that teens and newer drivers are more likely to be involved in collisions when there are passengers (and the risk goes up with the number of passengers), while elderly drivers are less likely to be involved in collisions when there are passengers. This suggests that the relative mix of risk and benefit (increased alerting) varies across lifespan and experience.
    Try here:
    VOLLRATH Mark ; MEILINGER Tobias ; KR├╝GER Hans-Peter.
    How the presence of passengers influences the risk of a collision with another vehicle.
    Accident analysis and prevention, 2002, vol. 34, no5, pp. 649-654

    The risk of a collision with another vehicle due to the presence of passengers is analysed in detail in a large sample of accidents from Mittelfranken, Germany, from the years 1984 to 1997. Using a responsibility analysis, the overall effect of the presence of passengers and the influence of modifying variables is examined. While a general protective effect of the presence of passengers is found, this is reduced in young drivers, during darkness, in slow traffic and at crossroads, especially when disregarding the right of way and passing a car. These findings are interpreted as a general positive effect of the presence of passengers who influence the driver’s behaviour towards more cautious and thus safer driving behaviour. However, passengers may also distract drivers’ attention in an amount which cannot be compensated for in all situations and by all drivers by cautious driving. Besides educational measure, a potential solution to this problem may be driver assistance systems which give an adapted kind of support when passengers are present.

  17. #17 Susan Och
    January 18, 2009

    I won’t continue a conversation if I know the other party is driving. “Call me back when you’re not behind the wheel. You need to concentrate.” I’m not important enough to be anyone’s final conversation.

    I think that the added responsibility of passengers makes me a better driver. Certainly a “co-pilot” is helpful for spotting deer and drunks, our two main dangers. Another person is useful for playing the part of navigator in strange neighborhoods, or for simply providing conversation or manning the radio on a long trip when the driver is bored or weary.

  18. #18 Susan
    January 15, 2012

    My teenage daughter runs constant commentary when we’re driving. She’s always pointing things out which is a distraction to me, particularly if we’re in an unfamiliar place. Between her, the GPS when it’s on and the dog whining… I literally cannot focus. It is downright dangerous. How does one stop a teenage girl from yacking so much?!?!

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