It's not using a cell phone per se, but the amount of concentration used.
There was a show on a few years back where a they set up a course of road cones to simulate local roads. Straight, curves, stop signs, etc. They even had a cardboard cut-out of a deer that they could drag across the road.
Then they sent out a driver who was just driving and he didn't hit any cones, stopped at the stop signs and stopped before hitting the "deer".
They they sent him out again but had him hold a casual conversation on a cell phone. He clipped a few cones, but stopped at the stop signs and didn't hit the deer.
Then they sent him out a 3rd time with a cell phone but this time they had him recite aloud the 7's times table (7x1=7, 7x2=14, etc). He clipped almost every cone, sailed passed the stop signs, and the deer never had a chance.
63tb