a friend was describing to me a tv documentary she'd seen, in which it was demonstrated that drivers who insist on talking on their cell phones while operating their vehicles, have approximately the same focus available for the task at hand (driving) as someone who is drunk.
i've seen this documented in past studies, as far back as ten years ago. my friend went on to tell me that in just about any "multi-tasking" setting, the brain is capable of paying primary attention to only one task, with the other tasks getting extremely short shrift on the cerebral back burner.
if you'd like confirmation of this phenomenon, all you have to do is pay attention to the behavior of drivers talking on their cell phones. they wander within their traffic lane, they suddenly realize they're about to miss a turn and veer across traffic, cutting off other drivers, they experience near-misses with adjacent vehicles, with pedestrians, with lamp posts. in short, they are a deadly menace on the road. one might as well be asleep at the wheel of an UNguided missile on wheels.
this irresponsible and hazardous behavior should be illegal in all states, just as driving under the influence is illegal. only a handful of states have enacted legislation making it so. oh, parenthetically, the excuse of using headphones, ostensibly leaving both your hands free, holds no water. it is what is going on inside the brain that is at issue.
bottom line -- hang up and drive ! ! !
by the way, the brain's inability to "multi-task" has implications for all those eager employment ads which describe a fast-paced work environment which requires energy, drive, a cheerful smile, and the ability to multi-task. gee, sounds like they're asking for the impossible, doesn't it? well, they are. it's far more productive in terms of quality and quantity, to slow down and focus on doing each task in turn. surprise.
back to vehicles for a moment -- the same splitting of attention occurs when one is listening to the car radio. the next time you're cruising, whether listening to talk radio or to music, try turning it off and notice how much more attuned you are to what's going on around you. it could save your life.