Sunday, July 20, 2008

Driving while using hands-free cell phones

A California law recently went into effect (July 1, 2008), banning the use of handheld cell phones while driving; hands-free devices, however, are allowed. While this is not a typical topic for Talking Brains, given that it affects TB West folks directly, and given that talking on a cell phone involves speech processing, I figure it is fair game.

It is clear that talking on a cell phone while driving, significantly impairs one's ability to drive; in fact, the impairment is on par with having a blood alcohol level of 0.08%, the legal limit. If driving under the influence is illegal, it seems reasonable to regulate the use of other influences on driving ability.

Here's the problem, though: most of the impairment comes from talking, not holding. In several studies by David Strayer and colleagues at the University of Utah, talking on a handheld OR hands-free cell phone impairs driving ability equally. Therefore, bans on handheld phones don't make any sense (unless you own stock in companies that manufacture hands-free devices). To reduce accidents, cell phone use needs to be banned completely during driving.

Critics might counter that we talk in the car all the time to our passengers. Does this research mean we should ban any form of conversation while driving? No. It turns out that Strayer's research has found that conversing with passengers does NOT produce the same kind of impairment on driving; passengers adjust their conversation as a function of driving difficulty, and many actually help out in some situations. After all, passengers have a stake in the performance of the driver as well. But the person on the other end of a cell phone conversation has no idea when break lights suddenly flash, or a ball rolls into the road, and therefore merrily chatters on.

A recent paper by Marcel Just et al. hints that the parietal lobe may be involved in the decrease in performance: in subjects who were performing a simulated driving task, parietal activation was down by 37% during concurrently listening to sentences compared to a no interference condition. Not sure what to do with this information, but since the blog is called Talking BRAINS, I thought I should mention it...

Notice to lawmakers: Banning handheld phones is a waste of time and (our) money. Well, maybe it's not a complete waste. Now I have an extra hand to hold my coffee.


Just, M.A., Keller, T.A., and Cynkara, J. (2008). A decrease in brain activation associated with driving when listening to someone speak. Brain Research, 1205, 70-80.

Strayer, D. L., & Johnston, W. A. (2001). Driven to distraction: Dual-task studies of simulated driving and conversing on a cellular phone. Psychological Science, 12, 462-466.

Strayer, D. L., Drews, F. A., & Crouch, D. J.(2006). A comparison of the cell phone driver and the drunk driver. Human Factors, 48, 381-391.

Strayer, D. L., & Drews, F. A.(2007). Cell-Phone-Induced Driver Distraction. Current Directions In Psychological Sicence, 16, 128-131.


Anonymous said...

The last sentence made my day. So true.

Thanks for the post. Scary topic for us bicyclists...

Anonymous said...


"Research has found that talking on a mobile phone is more distracting than holding an intelligent conversation with a passenger, but no more distracting than eating a cheeseburger."

While this research is not, strictly speaking, kosher, it does raise several important questions, not the least of which is how many accidents are specifically caused by finding those little onions in the cheeseburger when you clearly said "no onions" at the drive-thru? But since this IS Talking BRAINS, here's a more relevant one: do we need to check whether or not eating cheeseburgers depresses parietal lobe activation during driving simulations, or can we just assume that distractions other than conversations with passengers (with their attendant dynamic accomodations to the driving conditions) generally impair driving ability?

Anonymous said...

I am suspect of the research. Intuitively, it would seem our distractability will vary largely between individuals and occasions (e.g., an aircraft pilot would seem well equipped to hold a phone conversation and manage driving--unless maybe that conversation happens to require a lot of visual recall).

Furthermore, I know experimentally that I am less equipped for an accident when holding the phone than when using the cord. That has nothing to do with distraction, but has to do with having both hands to respond.

Greg Hickok said...

It seems the findings are pretty strong, so if you are suspect of the research, I'd like to know why.

No doubt we are all more able to manage a car control emergency much better with two hands on the wheel, but that's not the point. There is no law mandating that you have to drive with two hands, only that your free hand can't have a phone in it -- coffee if fine, however.

Jeff Olson said...

I wonder if conversing with a blind passenger would have the same effect as talking to someone on a cell phone...perhaps we also need a law banning blind passengers from speaking in a moving automobile!