More proof of avoiding mobiles while driving

Talking on cell phones while driving can impair drivers' visual attention such that it can add over 5 metres to their braking distance.

Talking on mobile phones while driving can impair drivers8217; visual attention to such a degree that it can add over 5 metres to the braking distance of a car travelling at 60 miles an hour, according to a new study.

Moreover, they cause almost twice as many errors as drivers driving without the distraction of a mobile phone conversation.

In the study led by Dr Melina Kunar, from the University of Warwick8217;s Department of Psychology, and Dr Todd Horowitz, from Harvard Medical School, the participants were asked to pay attention and respond by pressing one of two keys on a keyboard to a series of discs moving around a computer screen.

Some of the participants carried out the task with no distraction. Others carried out the task while also using speaker phones to simultaneously engage in a normal phone conversation, discussing things such as their hobbies and interests.

The researchers found that on average the reaction times of those engaging in the hands free telephone conversation were 212 milliseconds slower than those who undertook the task without the simultaneous telephone conversation.

A car travelling at 60 miles an hour would travel 5.7 metres 18.7 feet in that time so the distracting conversation would obviously increase any braking distance at that speed by the same amount.

The participants distracted by a phone conversation also made 83pct more errors in the task than those not in phone conversations.

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8220;Our research shows that simply using phones hands free is not enough to eliminate significant impacts on a driver8217;s visual attention,8221; said Kunar.

8220;Generating responses for a conversation competes for the brain8217;s resources with other activities which simply cannot run in parallel.

8220;This leads to a cognitive 8220;bottleneck8221; developing in the brain, particularly with the more complicated task of word generation,8221; he added.

The study suggests that hands free telephone conversations which require people to carefully consider the information they hear and then to make complex cognitive choices based on that information a business decision for instance have a particularly significant negative impact on a driver8217;s ability to process and act on the visual information that is critical to their driving performance.

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The study has been published in the Psychonomic Bulletin 038; Review 2008.