Scientists Point to Brain Region of 'Free Won't'

Research adds to the evidence suggesting that brain dysfunction can compromise free will

by Tom Valeo

October 24, 2007

The capacity for free will is said to reside in the brain’s frontal lobes, which enable us to decide what actions we will take. Now researchers have discovered a spot in the frontal lobes that could be called the home of our “free won’t.”

The dorsal fronto-median cortex (dFMC), located in the center of the brain behind the forehead, becomes active when we inhibit an action, according to the authors of a paper in the Journal of Neuroscience. Researchers Marcel Brass and Patrick Haggard think this may explain why some people are less adept at restraining their impulses.

“The capacity to withhold an action that we have prepared but reconsidered is an important distinction between intelligent and impulsive behavior,” said Brass, of the Max Planck Institute for Human Cognitive and Brain Sciences and of Ghent University. This could have significant neuroethical implications, the authors state in their paper, since the inability to restrain impulses has been linked to antisocial and criminal behavior.

The frontal lobes have long been recognized as the seat of judgment, foresight, planning and other distinctly human abilities. Damage to this area of the brain can produce a striking loss of impulse control, resulting in inappropriate, belligerent or even aggressive behavior. For example, one man with a tumor impinging on his frontal lobes suddenly began visiting prostitutes and making inappropriate sexual advances toward his stepdaughter. When the tumor was removed his behavior immediately returned to normal.

Brass and Haggard, of University College London, detected the impulse control area of the frontal lobes by using functional magnetic resonance imaging (fMRI). They studied the images of 15 right-handed people who were told to press a button on a keyboard at times they chose, and to occasionally hold back or veto their decision to press the button. The decision to refrain from pressing the button consistently produced activity in the dFMC—activity that never appeared when they followed through on their decision to press the button.

The experiment was modeled on the work of Benjamin Libet, who in 1983 published the results of a study in Brain involving subjects who were told to move a finger at a moment they chose. Brain monitoring showed that the “readiness potential” that signaled their decision to move their fingers appeared about a third of a second before they became conscious of their decision to move it. Yet, even though their decision to move a finger began unconsciously, they still retained the ability to reverse their decision and not move it. How could this be?

Libet hypothesized that the conscious mind has some sort of veto power that enables it to suppress brain activity initiated unconsciously. He could not identify a neural correlate to this veto process. Brass and Haggard, however, do not believe that the veto process requires conscious causation.

“Our results provide the first clear neuroscientific basis for the widely held view that people can refrain from doing something even if they genuinely wish to do it,” they write. “We speculate that the dFMC may be involved in those aspects of behavior and personality that reflect ‘self-control.’”

Legal implications

If that’s true, then their research adds to the rapidly growing body of evidence suggesting that brain dysfunction can compromise free will—a concept that challenges the conventional notion of criminal culpability. That evidence has become so compelling that the MacArthur Foundation recently authorized a three-year, $10 million grant for a Law and Neuroscience Project that will bring together scientists, legal scholars, jurists and philosophers in an effort to understand the legal implications of brain research. Work groups will consider issues such as addiction, brain abnormalities and decision making as they apply to criminal responsibility.

The U.S. legal system is built on the belief that criminal actions constitute voluntary acts. People who commit crimes involuntarily—while sleepwalking, for example, or while having a seizure—are not held accountable, even if they cause serious harm.

However, this dichotomy between voluntary and involuntary acts has become inadequate, says Deborah W. Denno, professor of law at Fordham University in New York.

“The new consciousness research suggests that much of our behavior takes place in a gray-colored world of semi-conscious impulses, automatisms and reflexes,” she writes in her paper “A Mind to Blame: New Views on Involuntary Acts,” published in Behavioral Sciences and the Law in 2003.

So Denno advocates adding a third category called “semi-voluntary acts” to the spectrum of behavior, thereby making criminal law more consistent with current knowledge about the brain.

“I think the courts should hear as much valid, reliable and expert information as they can to attempt to assess why someone did what they did,” she said. “I would never say that someone should get off because of this, but I am of the view that the courts should look at all the emerging evidence about how people think, and then decide how relevant it is to the particular behavior at issue. I think it’s important for the law because it provides a guide as to how much penalty people should get.”

In contrast, Stephen J. Morse, professor of law and psychiatry at the University of Pennsylvania, takes a more skeptical view of brain dysfunction as a mitigating factor. In a 2006 paper in the Ohio State Journal of Criminal Law he coined the term “Brain Overclaim Syndrome” to describe the widespread tendency to “make claims about the implications of neuroscience for criminal responsibility that cannot be conceptually or empirically sustained.”

Morse, who wrote an essay on “Moral and Legal Responsibility and the New Neuroscience” for the anthology Neuroethics: Defining the Issues in Theory, Practice and Policy, also does not believe that the experiment conducted by Brass and Haggard translates into real-life situations.

“If someone decides to move a finger, that’s different from impulse control,” he said. “But let’s assume there is a particular place in the brain that, when lesioned, prevents you from stopping certain kinds of impulses. If we could be sure that were the case, then that lesion would provide good evidence of that person’s inability to control behavior. At the moment, however, our understanding of the brain and impulse control is more limited.”