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4/5/11

Whose Fault Is It? Did Your Neurons Make You Do It?



Is free will a religious and metaphysical term while decision to act can be regarded without the spiritual baggage? Or will there always be entanglement whatever the term we use?

"We all believe we exercise free will . . . we decide what to do and when to do it. Free will, however, becomes more complicated when you try to think how it can arise from brain activity.

Do we control our neurons or do they control us? If everything we do starts in the brain, what kind of neural activity would reflect free choice? And how would you feel about your free will if [at one and a half seconds beforehand, you are told that you will act] before you yourself became aware of your own choice?"

Using intracranial recording, scientists have found "neurons in the human brain whose activity predicts decisions to make a movement, challenging conventional notions of free will."


Using an experimental procedure pioneered by Benjamin Libet, Itzhak Fried and colleagues "implanted electrodes in twelve patients, recording from a total of 1019 neurons." Libet had conducted research on free will years ago, and it had tremendous impact on both philosophic and scientific opinion on the subject. Libet's research allowed the conclusion that we are not aware of the readiness to act until after our muscles are committed to the action.

The procedure is this: patients looked "at a hand sweeping around a clock-face," and were told to "press a button whenever they wanted to." The patients then indicated where the clock hand had been pointing when they decided to press the button. The scientist thus had two data points. The time when the button was pushed and the time when the act of pushing was decided upon. In Libet's experiments the "decision" came roughly half a second after the the muscles contracted to push the button.

Fried and colleagues looked for the neurons that triggered this decision. They found such neurons abounded "in a region of the frontal lobe called the supplementary motor area, which is involved in the planning of movements."

What else did they find? Data corroborating Libet's findings. The neurons became activated before awareness of the decision. Roughly one quarter of these neurons signaled a change before the time the subjects declared as the moment they "decided" to push the button. How long before? "As long as one and a half seconds."

The implication? Is free will an illusion? Not necessarily. "The decision to move a finger hardly ranks as the same kind of free will we exercise when we make moral choices or major life decisions. To conclude that we aren’t fully responsible for our actions, for example, would be extremely far-fetched." Furthermore, people may not be very good at recalling the actual point where they noted the clock hand. Nothing in our perceptual world occurs in real time. (The light you see on a wall surface took eight minutes to reach that surface from the sun.)

Even if we don't have free will, according to Libet, we do have free won't--the ability to veto decisions. (See sidebar, this page.)

Think about this. Your brain can weigh consequences. It can predict what future effects will come from present actions. These consequences have emotional weight, and can prevent you--out of fear, for example--from commiting yourself to a bad course of action. If this be determinism, it can also be regarded as part of what philosophers call compatibilism--free will as compatible with determinism. From this vantage, you do have a kind of control. More

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