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John McGurk's blog

Power of 3 - Free Will or Readiness Potential? You (Still) Decide

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I spent many a pained philosophy tutorial contemplating the concept of free will. Through ignorance or arrogance, our tutor never mentioned the cognitive research which tested the idea.

An 80's experiment by Ben Libet at the University of California used ECG monitors to record brain activity to challenge the idea that we act independently of our spontaneous neural circuits. (New Scientist 11th August 2012 p 10)

1. Volunteers were encouraged to make spontaneous movement under the guidance of a very accurate timing device. They used the timer to declare their urge to make that movement. Libet found a 200 millisecond delay on average between this urge to act and the movement actually taking place. That's two hundred thousandths. (The human eye blinks in around half a millisecond for reference).

2. The ECG also recorded that a "by product" signalappeared in the brain a full 550 milliseconds before the action. It suggested that that our brain has already decided to act before we do. This so called "readiness potential" (RP) has been used to suggest that free will is an illusion.

3. But new research using more sophisticated measurement than what was available to Libet challenges this. Through computer modelling, researchers have found that neurons fire when we make a decision. That activity seems to occur at the same time as the neural activity previously identified as RP. So, RP is just one aspect of a lot of neural activity therefore can't we pin that down to something as complex as free will.

Furthermore they re-ran the Libet experiment this time instructing volunteers to act immediately they heard a click. (Libet had told them to ignore such information). The Researchers predicted that volunteers would act ahead of RP and that's exactly what occurred.

So our understanding of free will is still in play, though one neuroscientist Anil Seth of Sussex suggests otherwise.

Science, you can't make it up!

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davemettam
David John Mettam
06 March 2013 at 21:25

For another demonstration see exploringthemind.com/.../brain-scans-can-reveal-your-decisions-7-seconds-before-you-decide .

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