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Technology and Health News > Friday, May-02-2008

Choices: The brain plays in advance

The nervous system takes a decision ten seconds before the individual is conscious of it: a German study calls into question the concept of free will!

The human brain takes a decision almost ten seconds before the person is aware: the claim comes from researchers of Max Planck Institute for Cognitive Sciences in Leipzig, Germany, led by neuroscientist John-Dylan Haynes. With this claim, the German scientist are taking into question the principle of "free will" during the decision-making process.

The researchers asked 14 volunteers to undergo brain imaging during the course of a task: the experiment was to take a decision: in this case pressing between two buttons, with the right hand or with the left at the choice of the subject. At the same time, on a screen it was shown a stream of letters, at a rate of one every half second, and volunteers had to report the letter on the screen at the time of their decision.

By analyzing the data, researchers have noted that the first brain signals from the fronto-polar cortex, were visible even 7 seconds before their action on the button. And because the imaging techniques had a delay of about 3 seconds, neuroscientists believe that we can talk about a period of approximately 10 seconds between the decision and the awareness that it has been taken. "We believe we make decisions consciously," says Haynes, "but this data shows that the conscience of action represents only the tip of the iceberg."

The work of Haynes - who takes on (improving) some previous experiments conducted during the eighties by the American neuropsychologist Benjamin Libet - has attracted some negative reactions. "We knew already that our decisions can be triggered unconsciously - comments Chris Frith of University College London - and these results do not necessarily show that free will is only an illusion."

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Comments for Choices: The brain plays in advance

Justin Landeen

Justin Landeen
Justin Landeen
posted by Who at Friday, May-02-2008 18:07pm


posted by Abi at Friday, May-02-2008 23:11pm

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