Activity in certain areas of the brain signals what choice people are going to make up to ten seconds before they become consciously aware of their decision, reports a study published online in Nature Neuroscience.
John-Dylan Haynes and colleagues used functional magnetic resonance imaging (fMRI) to track activity in the brain while people viewed a stream of letters on screen, and then pressed a button. Each subject was asked to decide freely which of two buttons to press and when to press it.
The authors used a sophisticated statistical technique, called pattern recognition, to look at brain activity associated with each choice. Activity in prefrontal and parietal cortex predicted which button the person was going to press. This activity occurred up to ten seconds before subjects were consciously aware of having made a decision. These areas have previously shown to be involved in executive control, self-reflection and selection amongst different choices. These results suggest that high-level control areas begin to prepare an upcoming decision long before it enters conscious awareness.
John-Dylan Haynes (Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany)
Abstract available online.
(C) Nature Neuroscience press release.
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