For some years, now, I've haranged against people's using cell phones and gps systems while driving - hands-free or not. Either way, reasoned I, the brain is cluttered with too many things to think about at the same time.
Within the past couple of days, I've seen and heard reports of a study that showed that hands-free cell phone use could be just as (or more) distracting than using a cell phone hands-on. Especially distracting, they say, is using voice commands while driving. I can attest to this. My car accepts voice commands; but, in the nine months during which I've driven this car, I've used voice commands exactly once! (That time, I was just making sure that the system worked - a check out, if you will.)
Although this new study agrees pretty much with what I've been saying (Don't I love saying, "I told you so!") it caused me to do a small amount of additional research. The first thing I came up with was Linguistics 201: Language and the Brain. It points out that, "Tests have demonstrated increased neural activity in parts of the left hemisphere [of the brain] when subjects are using language." Let's see, now, what else keeps the left hemisphere of the brain busy? "The left hemisphere, on the other hand, came to control patterns that progress step-by-step in a single dimension, such as our sense of time progression, or the logical steps required in performing feats of manual dexterity...." This, I believe, includes the process of driving a motor vehicle.
BTW: I had read, and now understand a little better, that listening to instrumental music did not tend to distract drivers. I understand it a little better now after reading that, "...in modern humans, artistic ability tends to be centered in various areas of the right hemisphere." Non-linguistic music does not, therefore, tend to tie up the same resources in the brain as driving does.
Those of you who are well versed on the human brain (and remember more of what you've learned, no doubt) already know all of this. (I didn't get the message, telepathically!)