And this just in...
The study used an advanced driving simulator and had volunteers listen to and then retell novel stories over a hands-free cell phone. In one condition, the volunteer sat in an unmoving vehicle. In another condition, the volunteer drove through busy urban traffic. A final condition measured driving performance when the volunteer was not on the phone.
Replicating earlier research, the cell phone conversation interfered with driving (that is, driving was worse when volunteers were driving and talking on the phone than when they were driving without the cell phone distraction). The novel finding was that driving interfered with the fidelity of the conversation (that is, the quality of the conversation was worse when the volunteer was driving than when they had the conversation in an unmoving vehicle).
In other words, the cell phone conversation interfered with driving and driving interfered with the cell phone conversation.
This finding is important for two reasons, one theoretical and the other of more applied. On the theoretical front, the research helps scientists better understand how both driving and conversing place demands on attention. Over 100 years of research has taught us that the brain cannot do two attention-demanding activities at the same time without cost to both tasks and the combination of driving and talking on the phone is no exception to this rule.
The findings also have implications for the public policy debate. There are some who argue that they can be more productive when they conduct a little business as they commute to and from work. However, this research indicates that the quality of the conversation is not as good when they are driving as if they had the same conversation without driving.
Safety concerns aside, if the quality of a conversation matters to your business, then it is best to reserve your conversation for times when you are not operating a motor vehicle.
If you think that the person you are doing business with cannot tell that you are distracted by driving, you are kidding yourself.