How is conversing on a phone different from talking with a passenger in the vehicle?
There are two important differences. The first is that a passenger in a vehicle is aware of the driving situation and can even serve as an additional look-out for hazards. If there is aneeded pause in conversation, it happens, and the reasons are evident to all parties. The second is that phone use seems to carry a certain obligation of immediacy. When the phone rings, we feel compelled to answer it—whether it is convenient, safe, or appropriate to do so or not. We become focused on the phone call and lose the situational awareness so necessary for safe driving.
