From: Wade Smith (wade_smith@harvard.edu)
Date: Wed 16 Oct 2002 - 15:54:38 GMT
A question of will
The issue of free will has perplexed theologians and philosophers for
centuries - now neuroscience enters the age-old debate
By Carey Goldberg, Globe Staff, 10/15/2002
http://www.boston.com/dailyglobe2/288/science/A_question_of_willP.shtml
Try this: At a moment of your choosing, flick your right wrist. A bit
later, whenever you feel like it, flick that wrist again.
Most likely, you'd swear that you, the conscious you, chose to initiate
that action, that the flickings of your wrist were manifestations of
your will.
But there is powerful evidence from brain research that you would be
wrong. That, in fact, the signal that launched your wrist motion went
out before you consciously decided to flick.
''But, but, but,'' you'd probably like to argue, ''but it doesn't feel
that way!''
With that protest, you would be joining a great debate among
neuroscientists, philosophers and psychologists that is a modern-day
version of the age-old wrangling over free will.
The traditional conundrum went: ''How can God be all-knowing and
all-powerful and yet humans still have free will?'' And later: ''How can
everything be governed by the determinist forces of physics and biology
and society, and yet humans still have free will?''
Those questions still concern many, but the new neuro-flavored debate
over free will goes more like this: Is the feeling of will an illusion,
a wily trick of the brain, an after-the-fact construct? Is much of our
volition based on automatic, unconscious processes rather than conscious
ones?
When Daniel M. Wegner, a Harvard psychology professor and author of a
new book, ''The Illusion of Conscious Will,'' gives talks about his
work, audience members sometimes tell him that if people are not seen as
the authors of their actions, it means anarchy, the end of civilization.
And worse. Some theologies, they tell him, hold that if there is no free
will, believers cannot earn a ticket to heaven for their virtue.
In reality, neuroscience is not generally tackling the sweeping
philosophical issue of free will, but something much narrower, said
Chris Frith, a neuroscientist at University College London.
''There has been much recent work addressing the question of how it is
that we experience having free will, i.e., why and when we feel that we
are in control of our actions,'' he wrote in an e-mail.
That is not to say that neuroscience will never enter the philosophical
fray.
It could even be that, once the physiological basis of will becomes
better understood, ''You'll get a more mature, larger view of what's
going on and the question of free will might vanish,'' speculated V. S.
Ramachandran, director of the Center for Brain and Cognition at the
University of California at San Diego. No one argues about ''vital
spirits'' now that we know about DNA, he noted.
Meanwhile, the debate is still on, and near its center is an 86-year-old
University of California professor emeritus of physiology, Benjamin
Libet.
His seminal experiments on brain timing and will came out back in the
mid-1980s, and the results are still reverberating loudly today.
Just this summer, the journal Consciousness and Cognition put out a
special issue on ''Timing relations between brain and world'' that
prominently featured Libet's work. And, at a conference, titled ''The
Self: from Soul to Brain,'' held by the New York Academy of Sciences
last month, ''Libet'' rolled off more tongues than Descartes or Kant or
Hume or the other philosophers whose names usually come up when the
subject is will.
What Libet did was to measure electrical changes in people's brains as
they flicked their wrists. And what he found was that a subject's
''readiness potential'' - the brain signal that precedes voluntary
actions - showed up about one-third of a second before the subject felt
the conscious urge to act.
The result was so surprising that it still had the power to elicit an
exclamation point from him in a 1999 paper: ''The initiation of the
freely voluntary act appears to begin in the brain unconsciously, well
before the person consciously knows he wants to act!''
Libet's experiments continue to be criticized from every which angle. At
the New York conference, for example, Tufts philosopher Daniel C.
Dennett argued that it could be that the experience of will simply
enters our consciousness with a delay, and thus only seems to follow the
initiation of the action.
But, though controversial, the Libet experiments still stand and have
been replicated. And they have been joined by a growing body of research
that indicates, at the very least, that the feeling of will is fallible.
Among that research is the following experiment by Dr. Alvaro
Pascual-Leone, director of the Laboratory for Magnetic Brain Stimulation
at the Beth Israel Deaconess Medical Center.
A subject, he said, would be repeatedly prompted to choose to move
either his right or his left hand. Normally, right-handed people would
move their right hands about 60 percent of the time.
Then the experimenters would use magnetic stimulation in certain parts
of the brain just at the moment when the subject was prompted to make
the choice. They found that the magnets, which influence electrical
activity in the brain, had an enormous effect: On average, subjects
whose brains were stimulated on their right-hand side started choosing
their left hands 80 percent of the time.
And, in the spookiest aspect of the experiment, the subjects still felt
as if they were choosing freely.
''What is clear is that our brain has the interpretive capacity to call
free will things that weren't,'' he said.
Wegner's book discusses a variety of other mistakes of will. Among them
is the ''alien-hand'' syndrome, in which brain damage leaves people with
the sense that their hand no longer belongs to them, and that it is
acting - say, unbuttoning their shirt - out of their control.
Another recent book, ''The Volitional Brain: Toward a Neuroscience of
Free Will,'' includes a psychiatrist's description of a German patient
who felt compelled to stand at the window all day, willing the sun
across the sky.
Wegner argues that ''the feeling of will is our mind's way of estimating
what it thinks it did.'' And that, he said, ''is not necessarily a
perfect estimate.'' It is ''a kind of accounting system rather than a
direct read-out of how the causal process is working.''
In Libet's interpretation, free will could still exist as a kind of veto
power, in the fractions of a second between the time you unconsciously
initiate an action and the time you actually carry it out.
For example, he said in a telephone interview, ''The guy who killed the
mayor of San Francisco, he was obviously deliberating in advance, but
then when he gets to the mayor, there's still the process of, does he
now pull the trigger? That's the final act now. That is initiated
unconsciously, but he's still aware a couple of hundred milliseconds
before he does it and he could control it, but he doesn't.''
''That is where the free will is,'' Libet said.
Such veto power is not enough for many people, however. ''I want more
free will than that,'' Dennett complained at the conference.
He may not get it, but he will almost surely get more data about it.
Some neuroscientists are using new brain imaging technology to try to
pinpoint what happens in the brain when a person wills something. With
its help, and further work being done on patients with abnormal
volition, more progress appears likely.
''I think,'' Frith wrote, that ''in the next few years we will have
quite a good understanding of the brain mechanisms that underlie our
feeling of being in control of our actions.'' But that, he hastened to
add, ''does not in any way eliminate free will.''
Further comfort comes from Michael S. Gazzaniga, director of the Center
for Cognitive Neuroscience at Dartmouth College.
There is no need, he said, ''for depressing nihilistic views that we're
all robots walking around on someone else's agenda. It's the agenda we
build through experience, and the system is making choices.''
And just because some processes in the brain are automatic does not mean
they all are, he said. ''My take,'' Gazzaniga said, ''is that brains are
automatic and people are free.''
Carey Goldberg may be reached at G oldberg@globe.com.
This story ran on page C1 of the Boston Globe on 10/15/2002.
© Copyright 2002 Globe Newspaper Company.
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