Talking, driving too much for brain

Using a cellphone -- even with a hands-free device -- may distract drivers because the brain cannot handle both tasks.

Imaging tests show the brain directs its resources to either visual input or auditory input, but cannot fully activate both at the same time, researchers at Johns Hopkins University in Baltimore have found. They tested people age 19 to 35 by showing them a computer display while they wore headphones playing voices.

“Directing attention to listening effectively ‘turns down the volume’ on input to the visual parts of the brain,” said Steven Yantis, a professor in the Department of Psychological and Brain Sciences who led the study.

The report was published in the June 22 issue of the Journal of Neuroscience.