A thought provoking article in Scientific American - the nature of free will

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http://www.scientificamerican.com/article.cfm?id=the-will-to-power & sc=DD_2009111\

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The Will to Power--Is " Free Will " All in Your Head?

Neurosurgeons evoke an intention to act during brain surgery

 

Surely there must have been times in high school or college when you

laid in bed, late at night, and wondered where your “free will” came

from? What part of the brain—if it is the brain—is responsible for

deciding to act one way or another? One traditional answer is that

this is not the job of the brain at all but rather of the soul.

Hovering above the brain like Casper the Friendly Ghost, the soul

freely perturbs the networks of the brain, thereby triggering the

neural activity that will ultimately lead to behavior.

 

Although such dualistic accounts are emotionally reassuring and

intuitively satisfying, they break down as soon as one digs a bit

deeper. How can this ghost, made out of some kind of metaphysical

ectoplasm, influence brain matter without being detected? What sort of

laws does Casper follow? Science has abandoned strong dualistic

explanations in favor of natural accounts that assign causes and

responsibility to specific actors and mechanisms that can be further

studied. And so it is with the notion of the will.

 

Sensation and Action

Over the past decade psychologists such as Daniel M. Wegner of Harvard

University amassed experimental evidence for a number of conscious

sensations that accompany any willful action. The two most important

are intention and agency. Prior to voluntary behavior lies a conscious

intention. When you decide to lift your hand, this intention is

followed by planning of the detailed movement and its execution.

Subjectively, you experience a sensation of agency. You feel that you,

not the person next to you, initiated this action and saw it through.

If a friend were to take your hand and pull it above your head, you

would feel your arm being dragged up, but you would not feel any sense

of being responsible for it. The important insight here is that the

consciously experienced feelings of intention and agency are no

different, in principle, from any other consciously experienced

sensations, such as the briny taste of chicken soup or the red color

of a Ferrari.

 

And as a plethora of books on visual illusions illustrate, often our

senses can be fooled—we see something that is not there. So it is with

the sensation of intentionality and agency. Decades of psychology

experiments—as well as careful observation of human nature that comes

from a lifetime of living—reveal many instances where we think we

caused something to happen, although we bear no responsibility for it;

the converse also occurs, where we did do something but feel that

something or somebody else must have been responsible. Think about the

CEO of a company who takes credit—and bonuses worth many millions—if

the stock market price of his company rises but who blames anonymous

market forces when it tanks. It is a general human failing to

overestimate the import of our own actions when things go well for us.

 

Lest there by any misunderstanding: the sensations of the intention to

act and of agency do not speak to the metaphysical debate about

whether will is truly free and whether that even is a meaningful

statement. Whether free will has some ontological reality or is

entirely an illusion, as asserted forcefully by Weg­ner’s masterful

monograph, does not invalidate the observation that voluntary actions

are usually accompanied by subjective, ephemeral feelings that are

nonetheless as real as anything else to the person who experiences

them.

 

Telling Clues from Surgeries

The quiddity of these sensations has been strengthened considerably by

neurosurgeons. During certain types of brain surgery, neural tissue

must be removed, either because it is tumorous or because it gives

rise to epileptic seizures. How much tissue to remove is a balancing

act between the Scylla of leaving remnants of cancerous or

seizure-prone material and the Charybdis of removing regions that are

critical for speech or other near-essential operations. To probe the

function of nearby tissue, the neurosurgeon stimulates it with an

electrode that passes pulses of current while the patient—who is awake

and under local anesthesia to minimize discomfort—is asked to touch

each finger successively with the thumb, count backwards or do some

other simple task.

 

During the course of such explorations in 1991, neurosurgeon Itzhak

Fried, now at the University of California, Los Angeles, and his

colleagues stimulated the presupplementary motor area, part of the

vast expanse of cerebral cortex that lies in front of the primary

motor cortex. Activation of different parts of the motor cortex

usually triggers movements in different parts on the opposite side of

the body, for example, the foot, leg, hip, and so on. The medical team

discovered that electrical stimulation of this adjacent region of

cortex can, on occasion, give rise to an urge to move a limb. The

patient reports that he or she feels a need to move the leg, elbow or

arm.

 

This classical account was elaborated on by a recent study from Michel

Desmurget and his colleagues at the Center for Cognitive Neuroscience

in Bron, France, that was published in the international journal

Science. Here it was electrical stimulation of the posterior parietal

cortex, gray matter involved in the transformation of visual

information into motor commands—as when your eyes scan the scene in

front of you and come to rest on the movie marquee—that could produce

pure intentions to act. Patients made comments (in French) such as “It

felt like I wanted to move my foot. Not sure how to explain,” “I had a

desire to move my right hand,” or “I had a desire to roll my tongue in

my mouth.” In none of these cases did they actually carry out the

movement to which they referred. But the external stimulation caused

an unambiguous conscious feeling of wanting to move. And this feeling

arose from within, without any prompting by the examiner and not

during sham stimulation.

 

This was different from the cortical sector explored by the earlier

Fried study. One difference between the two stimulated regions was

that, at higher current levels, the patient actually moved the limb

when the target site was the presupplementary motor area. Parietal

stimulation, on the other hand, could trigger a sensation that actual

movement had occurred, yet without any motion actually occurring

(illusion of movement).

 

The take-home lesson is that the brain has specific cortical circuits

that, when triggered, are associated with sensations that arise in the

course of wanting to initiate and then carry out a voluntary action.

Once these circuits are delimited and their molecular and synaptic

signatures identified, they constitute the neuronal correlates of

consciousness for intention and agency. If these circuits are

destroyed by a stroke or some other calamity, the patient might act

without feeling that it is she who is willing the acting!

 

In the debate concerning the meaning of personal freedom, these

discoveries represent true progress, beyond the eternal metaphysical

question of free will that will never be answered.