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Obesity: Science weighs in Contact us Science
Inside the criminal mind

Lawyers, neuroscientists grapple with question: Is the fault in our brains, or in our selves?


By Sue Goetinck Ambrose / The Dallas Morning News

The real story of any crime is hidden inside the criminal's brain.

At least it used to be hidden.

Today's scientists can peek inside the brain, providing lawyers, judges and juries with once-invisible details about what goes on inside the criminal mind.

If the new brain science were foolproof, it could bring powerful new evidence to criminal cases. Already, legal experts say the latest brain techniques are influencing the outcomes of trials across the country. But many researchers warn that brain science as courtroom evidence may be, as Perry Mason used to say, incompetent, irrelevant and immaterial.

"Some of these defenses in my view take an extraordinarily narrow view of the causes of human behavior," said Raymond Dolan, a neuroscientist at the Institute of Neurology in London.

There is no doubt, researchers say, that modern science is getting closer to learning how the brain shapes people's actions and abilities. Certain regions of the brain are known to be devoted to seeing or listening, planning or remembering. Scientists can watch the waxing and waning of delicate nerve cell connections that seal in memories. High-tech scanners can capture thoughts flickering through the brain.

Brain scans can do a crude form of mind reading – picking up a difference between someone thinking about a face rather than a place. Other research suggests that damage to tissue in the front of the brain causes personality traits often seen in criminals. Recordings of brain electrical activity, some scientists say, can show whether someone is lying or telling the truth.

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But even though researchers caution that making the jump between these findings and real-world situations is difficult, sophisticated brain-probing techniques are seeping out of the laboratory and into the courtrooms.

An Iowa judge, for instance, is now deciding whether to admit as evidence brain-wave test results that a man says should clear him of a 1977 murder. The test measures an electrical brain signal that appears when a person is presented with a stimulus – words or a picture, for instance – that is recognizable to that person. In the Iowa case, news accounts say, the real murderer escaped by running behind a building through tall weeds. But the convicted murderer, Terry Harrington, showed no special brain response when asked whether weeds, sand or cement were behind the building. The real murderer would have had special brain responses, Mr. Harrington and his lawyers contend.

The brain signal, known as a P300 response, is widely accepted among scientists as able to distinguish what is familiar to a person, and what is unfamiliar. But some scientists say that although the technology works in controlled laboratory settings, it hasn't been rigorously tested in enough real-world situations to use inside the courtroom.

Images of the brain itself have also found their way into court. In a 1995 Virginia embezzlement case, a lawyer for the defense unsuccessfully used an MRI scan in arguing that the suspect's brain had been shrinking for some years, and that this condition kept him from forming the intent to commit the crime. Lawyers for John DuPont, the wealthy chemical heir convicted of killing Olympic wrestler Dave Shultz, ordered brain scans for their client. Similar brain arguments have been made in other cases – in New York and California, for instance – in the past decade and a half.

Although scientists have connected brain abnormalities with personality traits – including violence – often seen in criminals, making the connection in any one person is difficult, said Dr. Dolan. A scan that picks up a brain feature that strays from the norm doesn't mean that the brain defect is the cause of the criminal behavior, he said. Plenty of people who aren't violent have brain traits like those that show up in courtroom defenses.

In scientific studies, the connections between brain features and behavior show up because scientists study a large number of people, under very controlled circumstances, and average the results to see a trend.

It's also important to remember, Dr. Dolan said, that just because one part of the brain is connected with a trait like violence, it doesn't mean it's the only cause of violent behavior. Many parts of the brain contribute to any one behavior. And the brain isn't operating in a vacuum.

"Behaviors are determined by complex relations to our social environment," Dr. Dolan said.

Most researchers therefore acknowledge that it's difficult to link a brain scan to a particular person's mental state during a crime. Still, there are scientists who believe that such a link is plausible, and therefore, are willing to testify, said Jennifer Kulynych, a lawyer with the Association of American Medical Colleges in Washington, D.C., who also has a doctorate in neuroscience.

"There are researchers and scientists who believe that even though this evidence is not a conclusive demonstration, that it is evidence," she said. Some scientists believe if you can show that a defendant has a brain that is compromised, it is more likely that the defendant's thinking is compro- mised, she said.

And a judge's decision whether to admit brain evidence in a case isn't necessarily easy, Dr. Kulynych said. Federal courts and many state courts are required to determine whether expert testimony regarding brain evidence has a scientifically valid foundation. Making such a decision requires a considerably high level of sophistication about the brain and the research technique, something many judges don't have.

Juries will weigh in

Scientific considerations aside, it's unclear how society and juries will view evidence claiming that a brain disorder contributed to criminal behavior, experts say. It could be that juries would be more sympathetic to people who might have mental problems beyond their control. The opposite could also be true, said Hank Greely, a law professor at Stanford University in California.

"Does neuroscience lead us to conclude that certain people should be kept in jail forever?" he said. "Or should they have their sentences lengthened because of aspects of their mind that make them dangerous?"

At least one public defender has noticed that juries often react strongly to brain defenses.

"I've had cases where jurors probably looked at the defense of mental illness as not necessarily a good thing for my client," said Mike Mears, director of the Multi-County Public Defender Office in Georgia. "The idea that this person is different from us just exacerbates the fears that these jurors already have" about people with mental illness.

In a 1994 Georgia death penalty case, for instance, defense lawyers trying to get a softer sentence for their client argued that he had a family history of violent tendencies, and should be shown mercy because other family members had mellowed with age.

But the jury, Mr. Mears said, reacted the opposite way.

"The jurors said that's even more reason for this person to be put out of our midst. We've got to protect the rest of society from people like that," Mr. Mears recalled.

Some ethicists wonder whether brain findings may one day be used to put people in jail before a crime is even committed.

"Do we lock people up before they've committed a crime, even if we're confident they're going to?" said Dr. Greely. "Or does that run against our deepest beliefs in free will? Even if neuroscientists prove that in some contexts for some people there is no free will, do we as a society want to accept that?"

The extent to which people have control over their actions is starting to receive serious scrutiny in laboratory settings. For instance, scientists from Vanderbilt University recently discovered nerve cells in a special region of monkeys' brains that were devoted to "supervising" the monkey's behavior. The behavior was a simple one – how well the monkeys were able to control whether to shift their gaze when prompted by the researchers.

When the monkeys shifted their gaze when they weren't supposed to, brain cells dubbed the "oops" cells fired. When the monkeys controlled their gaze according to the scientists' prompts, entirely different cells – what scientists called the "yippee" cells – fired. A third set of nerve cells signaled how much conflict the monkey was experiencing, faced with the researchers' conflicting instructions, the scientists reported in the journal Nature last year.

Although findings on monkey gazes may seem to have little to do with criminal behavior, they put scientists one step closer to understanding how the brain controls behavior at the level of individual cells.

Much as the monkey might want to shift its gaze to gain a reward, sometimes the monkey can't, because its brain has already made the decision to do otherwise, said Jeffrey Schall, the psychologist who led the research.

"When we talk about free will, commonly, often what's meant is the sense that 'I could have done otherwise,'" Dr. Schall said. "In the legal sense, you're responsible for shooting that guy because you could have done otherwise."

But at the level of individual nerve cells and molecules, does the picture change?

"If you push this far enough, you can't say you could have done otherwise," he said. Even though it's clear that people make choices, he said, "the kind of free will that people commonly think they want, is something that – if we're being rigorous and scientific – is unavailable to us."

And there are already hints that some people have more control over their actions than others. Children with attention deficit hyperactivity disorder, one study found, were slower at stopping certain actions in a laboratory test than were children without the condition.

In other words, scientists say, every person is limited by his or her unique physical makeup, in one way or another.

"My freedom is constrained by my biology," said William Newsome, a neuroscientist at Stanford who studies how monkeys make decisions. "I do not have the freedom to get up in the morning and decide that I'm going to be Tiger Woods and go out and win the British Open. I don't have the body, I don't have the mind, I don't have the talent, and I don't have the skills that man has."

Unanswered questions

If scientists find that certain criminals are driven by their biology, society will have to figure out how to respond.

"Is it their fault, if the biology in the brain is sufficiently different?" Dr. Newsome said. "I'd say probably not. It's probably not something they have control over."

But, he added, "If they're abusing children and murdering or raping or whatever they're doing, it doesn't really matter whether it's their fault or not. We've got to separate them from society as a purely practical matter."

Such practical concerns may outweigh any insights into the nature of free will, Dr. Newsome said.

"The problem of free will and determinacy has been a problem of mankind for millennia," he said. "And if anyone had come up with a good solution, I assume that we would have heard about it by now."

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