by Kerri Smith
Think it over:
your brain might pre-empt your consciousness
when deciding what to do.
before they are consciously made.
Your brain makes up its mind up to ten seconds before you realize it, according to researchers.
By looking at brain
activity while making a decision, the researchers could predict what
choice people would make before they themselves were even aware of
having made a decision.
Ten seconds is "a lifetime" in terms of brain activity, he adds.
The volunteers were asked to press one of two buttons when they felt the urge to. Each button was operated by a different hand.
At the same time, a
stream of letters were presented on a screen at half-second
intervals, and the volunteers had to remember which letter was
showing when they decided to press their button.
Because of there is a delay of a few seconds in the imaging, this means that the brain activity could have begun as much as ten seconds before the conscious decision.
The signal came from a region called the frontopolar cortex, at the front of the brain, immediately behind the forehead.
This area may well be the
brain region where decisions are initiated, says John-Dylan Haynes,
who reports the results online (Unconscious
Determinants of Free Decisions in the Human Brain) in
Libet used a similar
experimental set-up to Haynes, but with just one button and
measuring electrical activity in his subjects' brains. He found that
the regions responsible for movement reacted a few hundred
milliseconds before a conscious decision was made.
Because moving the left
and right hands generates distinct brain signals, the researchers
could show that activity genuinely reflected one of the two
Although subjects are free to choose when and which button to press, the experimental set-up restricts them to only these actions and nothing more, he says.
What might this mean, then, for the nebulous concept of 'free will'?
If choices really are being made several seconds ahead of awareness,
But results aren't enough to convince Frith that free will is an illusion.
The brain activity could be part of this priming, as opposed to the decision process, he adds.
Part of the problem is defining what we mean by 'free will'. But results such as these might help us settle on a definition.
It is likely that,