clipped from: www.abc.net.au   

Using a hands-free device on a mobile phone is more distracting than sitting next to a talkative passenger, say US researchers.

handfree phone and driver

Their finding, published in the Journal of Experimental Psychology: Applied, adds to a growing body of evidence that mobile phones can make driving dangerous.

Professor Lee Strayer of the University of Utah and colleagues found in a series of experiments using driving simulators that hands-free mobile phones are just as distracting as handheld models
chatting on a mobile phone can slow the reaction times of young adult drivers to levels seen among senior citizens, and shown that drivers using mobile telephones are as impaired as drivers who are legally drunk
drivers using a hands-free device drifted out of their lanes and missed exits more frequently than drivers talking to a passenger
The difference between a mobile phone conversation and passenger conversation is due to the fact that the passenger is in the vehicle and knows what the traffic conditions are like