Many states (including California, New York, Washington, the District of Columbia, and Connecticut) have imposed laws requiring drivers to use hands-free devices to make phone calls. New Jersey even made violation of its law a first offense. But several studies over the years have found that talking on a hands-free device is not much safer than talking on a hand-held device.

A study by the American Psychological Association of over 500 drivers found that talking on a cell phone cut activity in areas of the brain used for driving by half. Drivers focusing on a phone conversation had slower reaction times, were less likely to recall objects on the road, and had a hard time noticing traffic around them. Researchers also noted that hands-free devices in the car posed the same hazards as hand-held devices.

A different study by the University of Utah tested drivers' use of hands-free cell phones on the road, and found (to no one's surprise) that chatty drivers were the main cause of traffic problems. Apparently, drivers talking on a cell phone were less likely to change lanes, and spent more time following slow-moving vehicles.

The latest research by Carnegie Mellon University questions hands-free laws, and whether their existence only gives drivers a false sense of safety. To test this theory, neuroscientist Marcel Just studied 29 volunteers who used a driving simulator inside an MRI brain scanner. The volunteers were tasked with driving a car along a virtual winding road, with and without distractions.

Researchers found that drivers would hit the guardrail and veer out of the center of the lane more often when they tried to answer true or false questions. Brain scans of the distracted drivers showed brain activity decreased in areas that process visual and spatial information, functions that are crucial for navigation. Once again, this proved that participating in a conversation is all it took to reduce a driver's focus on the road.

As reported in This is London, Just concluded:

1. Drivers need to keep not only their hands on the wheel, they  also have to keep their brains on the road. Drivers' seats in many vehicles are becoming highly instrumented cockpits and during difficult driving situations they require the undivided attention of the driver's brain.


2. The clear implication is that engaging in a demanding conversation could jeopardise judgment and reaction time.

So while there may be laws out there that ban the use of hand-held phones behind the wheel, the truth is the road will remain a dangerous place as long as drivers continue to carry phone conversations on hands-free devices - so be careful out there.

Link: Driving study deals blow to hands-free phones