Electromagnetic radiation from your mobile phone may impair your ability to make snap decisions, such as when driving a car, an Australian study shows.

The study, which will be published in the journal Neuropsychologia found evidence of slowed reactions, on both simple reactions and more complex reactions, such as choosing a response when there is more than one alternative.

The researchers found these effects after people were exposed to electromagnetic radiation equivalent to spending 30 minutes on the phone.

Lead researcher Professor Con Stough, director of the Brain Sciences Institute at Swinburne University of Technology in Melbourne, says the reactions tested experimentally have real-life equivalents, such as making braking decisions when driving a car.

"If you are driving a car and somebody runs out in front you, your simple reaction time is the time it takes to brake, while your choice reaction time could be the time it takes to decide between braking, turning left, turning right or hooting the horn to avoid the collision," he said.

The study's 120 volunteers received either active or 'sham' radiation emissions for 30 minutes before swapping for a further 30 minutes.

This meant a total active exposure of 30 minutes, equivalent to a long phone call.

The researchers then tested the study participant's reaction times and memory using a battery of neuropsychological tests.

As well as the effect on reactions times, the study found that radiation from mobile phones seems to improve working memory, used for example when remembering a phone number long enough to dial it.

But Professor Stough says this memory finding should be interpreted with caution because the underlying biological mechanism is not known.

A small effect
Professor Stough emphasises while the study raises the possibility that short-term exposure of mobile phone emissions affect brain activity, the effect is small.

"Further investigations such as functional magnetic resonance imaging are needed to confirm the neuropsychological changes associated with mobile phone emissions," he said.

"Whether the results will affect the way in which people make decisions about using mobile phones I don't know. Mobile phones are such a part of how we operate these days that it is unlikely."

Mobile phones were once thought to have a carcinogenic effect, but an international consensus found no support for this argument.

However, sleep studies lend support that mobile phone emissions alter brain activity.

Recent findings show that electromagnetic radiation received after making a mobile phone call stimulates the brain during the early stages of sleep.

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