Here’s molecular biologist John Medina on the subject of multitasking while driving:
Until researchers started measuring the effects of cell phone distractions under controlled conditions, nobody had any idea how profoundly they can impair a driver. It’s like driving drunk … Cell-phone talkers are a half-second slower to hit the brakes in emergencies, slower to return to normal speed after an emergency, and more wild in their “following distance” behind the vehicle in front of them… More than 50% of the visual cues spotted by attentive drivers are missed by cell-phone talkers. Not surprisingly, they get in more wrecks than anyone except very drunk drivers.
(John Medina, Brain Rules)