September 24, 2009

YOU EVER NOTICE...:

Free will is not an illusion after all (Anil Ananthaswamy, 9/23/09, New Scientist)

Long sceptical of Libet's interpretation, Jeff Miller and Judy Trevena of the University of Otago in Dunedin, New Zealand, attempted to tease apart what prompts the RP using a similar experiment, with a key twist.

They also used scalp electrodes, but instead of letting their volunteers decide when to move, Miller and Trevena asked them

to wait for an audio tone before deciding whether to tap a key. If Libet's interpretation were correct, Miller reasoned, the RP should be greater after the tone when a person chose to tap the key.

While there was an RP before volunteers made their decision to move, the signal was the same whether or not they elected to tap. Miller concludes that the RP may merely be a sign that the brain is paying attention and does not indicate that a decision has been made.

Miller and Trevena also failed to find evidence of subconscious decision-making in a second experiment. This time they asked volunteers to press a key after the tone, but to decide on the spot whether to use their left or right hand. As movement in the right limbs is related to the brain signals in the left hemisphere and vice versa, they reasoned that if an unconscious process is driving this decision, where it occurs in the brain should depend on which hand is chosen. But they found no such correlation.


...that folks who deny free will still get upset if you punch them in the face and take their wallet?

Posted by Orrin Judd at September 24, 2009 1:01 PM
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