Y: Ready.

D: Nice party, huh? I love these chips.

Y: Mmm-hmm.

D: You know, on the way over here I saw this guy talking on a cell phone while driving.      That's got to be dangerous.

Y: No it isn't. Only idiots can't drive and talk at the same time.

D: But your hands are off the wheel.

Y: I got one of those no-hands cell phones you can mount in a car. Don't believe what      anybody says. They're completely safe.

D: Unfortunately for you, smart-alec, I Got the Data.

Y: You what?

D: A study done by a psychologist and an engineer at the University of Rhode Island      had volunteers wear eye-tracking devices while they drove. The researchers found      that a driver's eyes move around a lot--we scan the road, check our speedometers,      and stay alert for surprises. When talking on a cell phone at the same time, though,      eye motions fell to almost zero--the subjects simply stared at the bumper ahead of      them.

Y: Yeah?

D: The issue seems to be not talking on the phone per se but concentrating on a second      task, such as making a decision with the person on the other end of the line. When      we do that, we take our mental energy away from driving. And that's dangerous!

Y: I knew that.

D: Mmm-hmm.