Hands-Free Cell Phones Reduce Driving Ability

Study Shows That Headsets, Speakerphones Distract Drivers

WebMD Health News

Nov. 16, 2004 -- Driving and chatting on hands-free cell phones just doesn't mix. That's the latest finding of a study looking into the "phoning while driving" debacle.

According to researchers at the University of Illinois at Urbana-Champaign, drivers who use hands-free cell phones struggle to see dangerous scenarios on the road ahead.

In the wake of legal restrictions citing that driving with one hand on the wheel and another on the phone are dangerous, many drivers have turned to headsets or speakerphones. But now, scientists say their study shows that hands-off cell phones result in bad driving too.

The study is reported in the journal Human Factors.

It doesn't matter how old you are, the report shows diminished reaction times and more detection errors for both teenage and senior drivers.

Twenty-eight drivers underwent a virtual reality experiment in which they were actively engaged in a hands-free cell phone call while a flickering, windshield-sized image of traffic and architectural scenes continuously played out in front of them. Each flicker produced a different image requiring a unique urgency of action. Images ranged from a child running into traffic or a simple change in a theatre sign.

Using software to track the participants' eye motion, researchers found that the more experienced drivers easily detected changes in color brightness, but their ability to spot critical changes requiring intervention was significantly reduced.

Older adults who were in a conversation on a hands-free cell phone were "no longer any faster or any more accurate in their ability to detect meaningful changes, such as a little girl running between cars in traffic, than they were able to detect changes that were not meaningful to driving safely," said psychologist Arthur F. Kramer, in a news release.

Younger drivers did better than their older peers when it came to detecting important driving changes, but their reaction time was reduced.

The impaired responses while on a hands-free cell phone were "in terms of seconds, not just milliseconds, which means many yards in terms of stopping distances," said Kramer.

In a separate experiment, Kramer and colleagues found that simply listening, which requires "fewer mental resources" than conversing, did not impair driving at all.