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.