Between the motion
And the act
Falls the Shadow
T.S. Eliot, "The Hollow Men"
Neuroscientist John-Dylan Haynes, has more than a proposition. He has evidence. How are we to construe the evidence? He has something to say on it. "We think our decisions are conscious," he says, "but these data show that consciousness is just the tip of the iceberg. This doesn't rule out free will, but it does make it implausible."
What data? At the Bernstein Center for Computational Neuroscience in Berlin, Haynes is pioneering research that collects it. In the April
Nature Neuroscience, he reports on the research. To determine what goes on moments before people sense they've reached a decision, he and his colleagues monitored neural currents in the brains of student volunteers as they decided. The "decision" could be random, reached quickly or slowly, as to whether to push a button with their left or right hands.
Seven men and seven women, 21 to 30 years old, were tested. Using an fMRI, or functional magnetic resonance imager, the team used pattern-recognition software to analyze the results of neural changes relative to thoughts.
Inside the brain scanner, the subjects watched random letters pass across a screen. They pressed a button with their right hand or a button with their left hand. Then they marked down the letter that had been on the screen in the instant they had decided to press the button.
The data? Up to the moment of being conscious of a decision, brain behavior signals were identified that let researchers know when the students had "decided" to press a button. These signals occurred on average 10 seconds before the students knew it themselves. About 70% of the time, the researchers could also predict which button the students would push.
Benjamin Libet's earlier experiments found roughly a half second delay between the impulse and the act. This, too, raised important questions about our belief in our ability at conscious decision.
Found in
Nature Neuroscience and the
WSJ.
Robert Lee Hotz at the
WSJ Science Journal has this to say:
Dutch researchers led by psychologist Ap Dijksterhuis at the University of Amsterdam recently found that people struggling to make relatively complicated consumer choices -- which car to buy, apartment to rent or vacation to take -- appeared to make sounder decisions when they were distracted and unable to focus consciously on the problem.
Moreover, the more factors to be considered in a decision, the more likely the unconscious brain handled it all better, they reported in the peer-reviewed journal Science in 2006. "The idea that conscious deliberation before making a decision is always good is simply one of those illusions consciousness creates for us," Dr. Dijksterhuis said.
There has been a long controversy as to whether subjectively 'free' decisions are determined by brain activity ahead of time. We found that the outcome of a decision can be encoded in brain activity of prefrontal and parietal cortex up to 10 s before it enters awareness. This delay presumably reflects the operation of a network of high-level control areas that begin to prepare an upcoming decision long before it enters awareness.
