Hands-free use while driving as distracting as holding phone

The researchers then monitored the driver's performance and reaction times during hands-free and hand-held phone conversations and without.

Melbourne, Dec 15 Drivers take note! Using your smartphone in hands-free mode while driving is just as distracting as holding the device in your hand, despite one being illegal and the other not, a new study has warned.

Researchers from Queensland University of Technology (QUT) in Australia measured the effects of mobile phone distraction on safety including reaction time and driving performance in an advanced driving simulator.

"We took a group of drivers and exposed them to a virtual road network which included a pedestrian entering the driver's peripheral vision from a footpath and walking across a pedestrian crossing," said Shimul Haque, from QUT.

The researchers then monitored the driver's performance and reaction times during hands-free and hand-held phone conversations and without.

The reaction time of drivers participating in either a hand-held or hands-free conversation was more than 40 per cent longer than those not using a phone. In real terms this equates to a delayed response distance of about 11 metre for a vehicle travelling at 40 kilometres per hour, the researchers said.

"This shows hands-free and hand-held phone conversations while driving have similar detrimental effects in responding to a very common peripheral event of a pedestrian entering a crossing from the footpath," said Haque. It was the cognitive load required to hold a conversation that was the distraction, not whether or not the driver was holding a phone, he said.

"It appears that the increased brain power required to hold a phone conversation can alter a driver's visual scanning pattern," he added.

"In other words the human brain compensates for receiving increased information from a mobile phone conversation by not sending some visual information to the working memory, leading to a tendency to 'look at' but not 'see' objects by distracted drivers," said Haque.

The distraction of a mobile phone conversation is not the same as an in-car conversation with a passenger because the non-driver can alter their dialogue based on the driving environment, for example stop talking when approaching a complex driving situation.

Haque said this raised a serious question on the appropriateness of mobile phone use laws while driving, which only impose a ban on hand-held mobile phone use but allowed drivers to use mobile phones with a hand-free device. The study also found the reaction time of provisional licence holders was double compared to those who held an open licence, said the researchers.

"Despite provisional licence holders in this study averaging a driving experience of more than two years, the detrimental effects of mobile phone distraction showed P-plate drivers had an increased probability of failing to detect a pedestrian," said Haque.

PTI