[Chris B.]

Also, the part of your brain used to talk in a normal conversation and process and respond logically to the person or people you are talking with is the same the part of your brain that is used to make decisions and recognize things while driving. That's why when you are talking to someone who is paying attention while driving a car they sometimes shut up and pause while talking because their brain is trying to process something they see on the road.

An issue with cell phone use while driving, even hands free, is that many people try to pay more attention to the conversation than to their driving and what's going on around them, while passengers int he car talking with the driver seem to understand more that the driver may have to stop talking for a moment here and there to react to traffic.

I remember reading some interesting research about this topic a few years back. Its one reason I rarely answer my phone in my car even when using Bluetooth hands free devices.