Benjamin Libet

http://en.wikipedia.org/wiki/Benjamin_Libet#Implications_of_Libet.27s_experiments 　より

【　Implications of Libet's experiments　】

Libet's experiments suggest that unconscious processes in the brain are the true initiator of volitional acts, and free will therefore plays no part in their initiation. If the brain has already taken steps to initiate an action before we are aware of any desire to perform it, the causal role of consciousness in volition is all but eliminated.

Libet finds that conscious volition is exercised in the form of 'the power of veto' (sometimes called free won't); conscious acquiescence is required to allow the unconscious buildup of the readiness potential to be actualized as a movement. While consciousness plays no part in the instigation of volitional acts, it retains a part to play in the form of suppressing or withholding from certain acts instigated by the unconscious. Libet noted that everyone has experienced the withholding from performing an unconscious urge. Since the subjective experience of the conscious will to act preceded the action by only 200 milliseconds, this leaves consciousness only 100-150 milliseconds to veto an action (this is because the final 50 milliseconds prior to an act are occupied by the activation of the spinal motor neurones by the primary motor cortex, and the margin of error indicated by tests utilizing the oscillator must also be considered).

The event that the brain becomes aware that it has made a choice is simply more information processing for a neuroscientist while dualist philosophers and religious people raise objections against the scientific view. For a scientist, there is no reason that consciousness is something else than what happens in the nervous system. Therefore, the scientists would go on to explicate the processes underlying consciousness itself instead of interpreting consciousness as a supernatural power. One brain part may be able to suppress the decision that another brain part has made after finding out about it, explaining the power of veto in a scientific way.