Hands-free mobile phones impair driving
Publication Date:07/03/2008
Using a hands-free mobile phone while driving distracts drivers enough for them to veer out of their lane and hit guardrails at the side of the road, a study has found.
What do we know already?
Lots of studies have looked at the impact of doing another task while driving. Overall, these studies show that the brain can't cope with doing two things at once and that driving performance deteriorates when people are asked to do something else at the same time.
Since December 2003 it has been illegal in the UK to use a hand-held mobile phone while driving.
But some recent studies have shown that people using hands-free phones while driving are just as likely to have a car crash as those using hand-held phones.
This study is the first to use brain imaging to look at the effects of doing a listening test while driving a car in a simulator.
What does the new study say?
The study found that listening reduces activity in the part of the brain associated with driving by more than a third. This can cause drivers to weave out of their lane or hit the guardrail at the side of the road.
Researchers have said these are the same type of driving errors that happen when a person drives under the influence of alcohol.
Tell me more about the study's findings
In the study, 29 volunteers used a driving simulator while they lay inside a magnetic resonance imaging (MRI) scanner. The scanner used in the study recorded the activity in 20,000 different areas of their brain, each about the size of a peppercorn.
Volunteers steered a car along a virtual winding road at a fixed speed while the scanner recorded the activity in their brain. The volunteers did this test twice: once with no distractions, and again while listening to statements on general knowledge, which they had to decide were true or false.
The study found that the brain activity dropped most in the part that processes sensory information, which is critical for spatial sense and navigation. Activity also fell in the part of the brain that processes visual information.
Where does the study come from?
The study was done by researchers from Carnegie Mellon University in Pittsburgh, USA. It was published in a scientific journal called Brain Research.
How reliable are the findings?
This was a small study done under experimental conditions which attempt to reproduce a real driving situation. The study was well done, but it could been done in a way that better reflected true driving conditions. For example, instead of using a mouse with their right hand to guide the car in the simulator, the volunteers could have been asked to use a steering wheel. And, instead of having to answer questions by clicking a mouse with their left hand, the volunteers could have been required to answer questions verbally, like they would in a real driving situation.
Because the listening task used in this study did not require the volunteers to speak, the impact of having a mobile phone conversation may be more disruptive to driving than this study suggests.
What does this mean for me?
If you drive and use a hand-free mobile phone then this study has important findings for you.
Because driving and listening involve two different networks of the brain, scientists had thought that people could do these tasks at the same time without one affecting the other. But this study shows that there's only so much the brain can do no matter how different the tasks are. Having a mobile phone conversation can distract from driving, and cause driving errors that could lead to crashes.
It's important to note that having a conversation using a mobile phone is not the same as having one with a passenger. If you're driving and talking to someone in the passenger seat, the passenger can also see the road and can stop talking if you need to pay extra attention to driving. But a person on the other end of the phone can't see the traffic situation, and won't stop talking at critical driving moments. You might carry on talking even though it's dangerous, because you don't want to appear rude.
What should I do now?
If you drive and use a hands-free mobile phone you might want to think whether you really need to. Although it's not illegal to use a hands-free phone while driving, police can prosecute drivers for failing to have proper control of the vehicle if they are distracted by a mobile phone conversation. Some companies ban their staff from using a hands-free phone while driving.
If you really do need to use a hand-free phone while driving then it might be a good idea to let the person you're talking to know that you are driving. That way, if you need to end a conversation suddenly, they will know why and not take offence.
From:
Just MA, Keller TA, Cynkar J. A decrease in brain activation associated with driving when listening to someone speak. Brain Research. 2008. (Available online to Brain Research subscribers at http://www.sciencedirect.com)
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