‘Hands Free’ Is Not Brain Free

I’m slow to post on this, but I’ve finally gotten around to reading a new cell-phone driving study from the indefatigable David Strayer and colleagues from the University of Utah’s Applied Cognition Laboratory, via The Journal of Experimental Psychology: Applied.

With all the usual caveats (a small sample of student-aged drivers in a simulated driving environment), this study is of particular interest for addressing a question one often hears: How is talking on a phone while driving any different than talking to a passenger?

Among other things, test drivers were asked to exit a highway at a rest stop area under different conditions — while on the phone, while a passenger was present, etc. The researchers found that “drivers in the cell phone condition were four times more likely to fail task completion than drivers in the passenger condition.” (these were the socially sanctioned, but arguably no less distracting, ‘hands free’ phones, by the way).


They write: “On the strategic level of performance, cell phone drivers performed poorly at the navigation task. Two nonmutually exclusive explanations can be provided for this deficit: First, drivers conversing on a cell phone may experience problems with keeping the intention of exiting at the rest area in working memory, or second, drivers may not sufficiently process information from the driving environment (exit signs). Some support for the latter hypothesis comes from studies demonstrating inattention blindness in cell phone drivers (Strayer et al., 2003).”

What’s particularly interesting here is the way the conversation also changed with the cell-phone. Drivers made fewer references to traffic on the cell phone (because the person on the other end isn’t sharing the experience, or presumably interested in sharing it), and what’s more, actually started to speed up their conversation, even as it grew less multi-syllabic: “Also, quite surprisingly drivers conversing on the cell phone increased their production rate when talking on the cell phone, which is contrary to the predictions of the modulation hypothesis. More interesting, this happened even as those drivers in the passenger condition tended to reduce their production rate.”

The speech was getting simpler, in other words, even as it grew faster.

Drivers on cell phones, the author speculated, “may have attempted to dominate the conversation to avoid having to engage in speech comprehension, whereas with in-vehicle partners, it may be easier to relinquish control, given that the partner can be relied on to accommodate with his or her contributions.” (I’ve overheard quite a few cell-phone conversations where it seemed the caller was trying to dominate the conversation).

As study co-author Frank Drews told the Salt Lake City Tribune:

“It’s crazy. They talk faster. It’s quite counterproductive for driving safely,” Drews said. “There is an obviously malevolent influence.”

And, of course, it depends on who the passenger is: “For example a passenger who is too ‘supportive’ by constantly commenting and directing attention in an overcontrolling fashion has a potentially negative impact on performance.” (what I call the ‘Hyacinth Bucket syndrome’).

See the video here.

This entry was posted on Thursday, December 4th, 2008 at 4:33 pm and is filed under Drivers, Traffic Psychology, Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

5 Responses to “‘Hands Free’ Is Not Brain Free”

  1. mdf Says:

    “How is talking on a phone while driving any different than talking to a passenger?”

    This is just a useless distraction. Here is a better question:

    Over the last 20 years or so, we have a cellphone using population that probably went from exactly zero to virtually everyone who can drive a car.

    Over the same interval, the number of fatalities per year has remained essentially unchanged.

    The Question:

    Given cell phone use while driving is incredibly dangerous, where is the excess human wreckage?

  2. Karl-On-Sea Says:

    MDF – do you think the same could be said of drink driving?

    Put it this way: it’s easy to spot someone who’s using a cellphone while driving. They struggle to keep in their lane, brake late & then too hard, and then drive too slowly for the traffic conditions as they compensate.

    All the same sort of errors that are typically seen in DUI cases.

    These don’t sound like a recipe for ‘good’ driving to me.

  3. mdf Says:

    “do you think the same could be said of drink driving?”

    If no one drank 20 years ago, and today almost everyone who could drive a car drank, and data shows no substantial change in accident fatalities, even in the face of incontrovertible proof that driving drunk is a seriously bad idea for numerous reasons, and there is evidence some people are driving drunk (a few cars now and then spotted with cocktail glasses casually held out the windows, riotous parties in the back seats, etc) then one could (should!) indeed question the entire business of whether or not “drunk driving” is worth caring about to the point of a special law against it.

    Of course, today we have utterly undeniable evidence of the fact that drunk driving is creating a massive pile of human bodies (I’ve selected one of thousands of hits here):

    “In 2006, there were 13,470 fatalities in crashes involving an alcohol-impaired driver (BAC of .08 or higher) – 32 percent of total traffic fatalities for the year.”

    Now, in the face of this kind of data, I don’t think anyone needs to conduct experiments as to why driving drunk is bad, model the chemical changes that create the deficiency in the brains of drivers, and stand before legislative committees begging for a law against drunk driving. The menace is clear, the decision is obvious.

    Does cellphone use have similar support? Well, we have the instant report on the low-level cognitive stuff cited above, that shows the risk. But then we have real-world data. Here is a typical report:

    Executive summary: even after years of research and monitoring, direct reports say about 1% of all crashes are cellphone related, but unspecified critics — perhaps bothered because the death toll isn’t as high as they would ‘like’? — argue about under-reporting.

    Maybe. However, I would say that if using a cellphone while behind the wheel is as demonstrably dangerous as driving drunk, we would see the effect clearly, and it would closely track the deployment of cellphone usage in the broader population. Consider (say) 10% of all traffic deaths are because someone was on a cellphone. At rates near about 1995, we would expect, then, today, an excess of about 4200 people per year … or something like 46-47 thousand people killed on the roads in the USA.

    Well, this appears not to be the case. More so, the fatality data is surprisingly flat — I haven’t run the tests, but to my eyes it isn’t totally out of the question that the real incidence is statistically indistinguishable from zero. (A statement, if true, doesn’t deny these kinds of accidents/deaths occur, but simply says that they are well inside the random noise of data gathered to date.)

  4. db Says:

    Shouldn’t you also factor in the increased safety of vehicles, which has presumably saved a large number of lives that would have been lost in the vehicles of 20 years ago? So if conditions/behavior stayed the same and cars got safer, there should have been a decrease in fatalities. Since fatalities remain at the same level, there must be additional conditional/behavioral dangers that have been causing fatalities. Seat belt use has also increased, so that should have improved the statistics as well.

    I think it’s also quite plausible that cellphone use hasn’t much increased the number of serious collisions leading to death, but has significantly increased the number of rear-enders and injury-causing crashes. It seems to me that it’s still rare to see a red light run by a driver on a cellphone, but it’s very common that the same driver would rear-end another car when traffic stops suddenly.

  5. bonzadog Says:

    I’m not sure why this discussion is exclusively related to traffic fatalities.
    If driver one is on the phone and holding up traffic flow, and driver two recklessly drives in order to put D1 behind him, would not an accident attributable to cell phone use (D1), but not officially recorded as such, be related? In other words, how much of reckless city driving might be ascribed to a faster-paced environment, combined with impatience with phone dawdlers, who effectly force those of us w/o distraction to drive more defensively, hence tying up the natural flow of traffic.

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