Well, the research is coming in on the use of mobiles while driving and it ain’t looking good. Hands-free does not make a difference it seems, it’s the seriousness of the conversation.
But does chatting to passengers have the same detrimental effect on driving? An earlier study found that it does not. That research, led by Frank Drews of the University of Utah, analysed the performance of young drivers using a vehicle simulator. Dr Drews found that when using a hands-free phone, a volunteer “drove” significantly worse than he did when just talking to someone playing the role of a passenger. Passengers, the researchers believed, might even help road safety by commenting on surrounding traffic.
The reported does not seem to have distinguished between idle chatter with people in the car and serious conversation. But I could see notices going up warning people against serious conversations in person or on the phone, while in a car.