Thursday, March 6, 2008

Driving While Under the Influence of fMRI

What will someone cram into an fMRI machine next? Earlier this week I posted about the use of functional magnetic resonance imaging (fMRI) to study brain activity in keyboard musicians while they were improvising jazz. It would now appear that even drivers with cell phones are not safe from fMRI researchers.

Brain Research just posted an in-press manuscript titled: "A decrease in brain activation associated with driving when listening to someone speak".

Why was this study done?
"Behavioral studies have shown that engaging in a secondary task, such as talking on a cellular telephone, disrupts driving performance. This study used functional magnetic resonance imaging (fMRI) to investigate the impact of concurrent auditory language comprehension on the brain activity associated with a simulated driving task."
Despite the title of the article, they did not study actual driving -- the sheer size of a decent fMRI scanner precludes this. To see the difficulty, imagine driving down the road with a your head stuffed inside a roll of toilet paper that is 7 feet in diameter. By the way, the toilet paper roll also weighs several tons, and has magnetic and radio frequency fields strong enough to send a cell phone flying and frying. Understandably, the investigators chose to simulate driving and cell phone conversations by other means.
"Participants steered a vehicle along a curving virtual road, either undisturbed or while listening to spoken sentences that they judged as true or false. "
How did the simulated drivers do?
"The dual task condition produced a significant deterioration in driving accuracy caused by the processing of the auditory sentences. At the same time, the parietal lobe activation associated with spatial processing in the undisturbed driving task decreased by 37% when participants concurrently listened to sentences."
The bottom line:
"The findings show that language comprehension performed concurrently with driving draws mental resources away from the driving and produces deterioration in driving performance, even when it does not require holding or dialing a phone."
This conclusion is not exactly a bolt from the blue -- they cite a number of other studies that echo the same conclusion: your driving sucks when you use a cell phone, hands-free or not.
For the full article, please see: Marcel Adam Just, Timothy A. Keller, Jacquelyn Cynkar. A decrease in brain activation associated with driving when listening to someone speak. Brain Research (2008), doi: 10.1016/j.brainres.2007.12.075.
(via MedPage Today)


Ellen said...

This would seem to suggest that any human speech the driver was listening to would lead to a decrease in his/her ability to drive. So, having someone in the front passenger side yaking away into the driver's ear would have a similar effect to the hands-free cell phone in that both leave the driver with both hands to steer and both ears to hear the yaking. My question is this: If the driver's spouse is the one responsible for the yaking, either in the phone or car, does the driver still demonstrate impaired driving? Or does that buzzing sound whining about "you should've taken that last left turn", not require the brain power that a stranger's voice does?

The Samurai Radiologist said...

That's a great question.

Many of us could probably swap anecdotes in which conversing with passengers distracted us from our driving. However, a live conversation may not be as bad a distraction as one might think.

This is supported by a great study by Drews et al titled Passenger and Cell-Phone Conversations in Simulated Driving. In this study, they found no significant difference between a control condition (driving only) and conversation with a passenger. However, they found a significant increase in driver errors with cell-phone conversation, compared to passenger conversation.

Why the difference? Here's the money quote from that article: "...passenger conversations differ from cell phone conversations because the surrounding traffic becomes a topic of the conversation, helping driver and passenger to share situation awareness, and mitigating the potential effects of conversation on driving."

Here's another excellent study form the same U of U lab, titled Fatal Distraction? A comparison of the cell-phone driver and the drunk driver. In this experiment, they found that when "...controlling for driving difficulty and time on task, cell-phone drivers exhibited greater impairment than intoxicated drivers."

This same study found no difference in driving impairment between the use of a hand-held vs. a hands-free device.

There are many other great papers on this same topic by David Strayer and colleagues at the University of Utah Applied Cognition Lab.