An anonymous reader notes a Reuters report of a study, published in the Journal of Experimental Psychology: Applied, confirming that Mobile phone calls distract drivers
far more than even the chattiest passenger, causing drivers to follow too closely and miss exits. California's ban
on using a handheld cell phone while driving, which went into effect last summer, is looking less than fully effective. A handful of other states have instituted similar bans, but none has forbidden driving while talking on a cell phone at all. "Using a hands-free device does not make things better and the researchers believe they know why — passengers act as a second set of eyes, shutting up or sometimes even helping when they see the driver needs to make a maneuver."