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Last Updated: Saturday, 20 December, 2003, 01:00 GMT
Brainwave fault explains slip-ups
Tired woman
Mistakes could be blamed on sleepiness
Scientists have found an explanation for those mornings where you put coffee on your cornflakes and the cat in the washing machine.

They say it is because of a change in the kind of brainwaves someone produces.

But the researchers, who presented their findings to the Physiological Society Conference, said the change could have more serious consequences.

They say it may have been a factor in accidents like the Chernobyl disaster.

Random test

A team from the Medical Research Council's cognitive and brain sciences unit in Cambridge examined brainwaves produced by people as they made mistakes.

It's the sort of mistakes you make especially when you're feeling tired or sleepy
Dr Avijit Datta, Medical Research Council
Volunteers took part in a 10-minute repetitive action test that requires prolonged periods of concentration.

They were shown random numbers on computer screens roughly once every second. Every time a number appeared, they had to press the mouse button.

But if they saw the number three, they were told not to press the mouse.

Monitoring of the volunteer's brainwaves showed they were more likely to make a mistake following a drop in levels of a type of brainwave called P300.

Dr Avijit Datta, who led the research, said: "It's the sort of mistakes you make especially when you're feeling tired or sleepy, like accidentally putting coffee on your cornflakes instead of milk.

"But you have to remember that these sorts of mistakes have also been implicated in the Chernobyl disaster and the three-mile island accident."

'Poor performance'

"We knew from previous brain imaging which part of the brain is used when these types of mistakes are made, but we wanted to find out how the actual brainwaves themselves changed."

"We looked at P300 waves and we found that if they began to fall, we knew a mistake was likely to happen.

"And because of the nature of the test, we knew that it was not due to changes in reaction time, so the subjects were no faster or slower at performing, just more error-prone."

He added: "It happens about a third of a second after the stimulus. For example, if you were driving a car and a child stepped out in front of you, it would generate P300 waves a third of a second later.

"If you generate a big response, then your foot hits the brake. But if it's only a small response then a mistake is more likely."

He added: "We know from a previous study that these mistakes are often linked to the sleep cycle and internal body clock."

Researchers are now working with patients suffering from sleep disorders and children who suffer from attention disorders and poor performance at school.

They said it might even be possible to measure the brainwaves with simple electrode pads on the skull which could be used in a car to check if someone is liable to make a mistake while driving.


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