tisdag 14 februari 2012

Concious experience lag behind the underlying events in the brain/Evans II

Nu börjar Jonathan Evans närma sig pudelns kärna i boken Thinking Twice - two minds in one brain. Åtminstone jag fascineras mycket av de tankegångar jag presenterar här nedan.
Scientists have known for some years that conscious experience lag behind the underlying events in the brain. It has been shown that conscious experience may be delayed by up to half a second beyond the sensory stimulation. Moreover, this experience is then referred back in time to the point where the stimulus actually reached the sensory areas of the brain, creating an illusion of conscious intentional control and making us unaware of the lag.

This can be seen, for example, among tennis players. When they return a fast serve they often report that they saw the direction of the serve and intentionally played the return to a particular area of the court. In fact, the timing is so that the action of returning the serve must have been initiated prior to the perception of the serve registering any conscious experience at all.
More recently is has been shown that this is also in a way true for free choice decision making and now it becomes really interesting. In one study participants are asked to make a free choice at any time to press a key with either their left or right index finger. A sequence of random letters is displayed on the screen, one at a time, and the participant is asked to indicate which was present when they made their decision to press a key. This gives the timing of the 'free choice' in the person´s consciousness. The researchers where able to show anticipatory brain activity was present up to 10 second ahead of the decision of using left or right hand to press the key. Even with the time lag of the brain scanner the researchers often knew themselves seven seconds before the participant what decision they were going to make. So much for the idea that free will is exercised by the conscious person.
 Har vi alls någon fri vilja?

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