Ideas 2011 July/August 2011

The Brain on Trial

Advances in brain science are calling into question the volition behind many criminal acts. A leading neuroscientist describes how the foundations of our criminal-justice system are beginning to crumble, and proposes a new way forward for law and order.

Beyond customized sentencing, a forward-thinking legal system informed by scientific insights into the brain will enable us to stop treating prison as a one-size-fits-all solution. To be clear, I’m not opposed to incarceration, and its purpose is not limited to the removal of dangerous people from the streets. The prospect of incarceration deters many crimes, and time actually spent in prison can steer some people away from further criminal acts upon their release. But that works only for those whose brains function normally. The problem is that prisons have become our de facto mental-health-care institutions—and inflicting punishment on the mentally ill usually has little influence on their future behavior. An encouraging trend is the establishment of mental-health courts around the nation: through such courts, people with mental illnesses can be helped while confined in a tailored environment. Cities such as Richmond, Virginia, are moving in this direction, for reasons of justice as well as cost-effectiveness. Sheriff C. T. Woody, who estimates that nearly 20 percent of Richmond’s prisoners are mentally ill, told CBS News, “The jail isn’t a place for them. They should be in a mental-health facility.” Similarly, many jurisdictions are opening drug courts and developing alternative sentences; they have realized that prisons are not as useful for solving addictions as are meaningful drug-rehabilitation programs.

A forward-thinking legal system will also parlay biological understanding into customized rehabilitation, viewing criminal behavior the way we understand other medical conditions such as epilepsy, schizophrenia, and depression—conditions that now allow the seeking and giving of help. These and other brain disorders find themselves on the not-blameworthy side of the fault line, where they are now recognized as biological, not demonic, issues.

Many people recognize the long-term cost-effectiveness of rehabilitating offenders instead of packing them into overcrowded prisons. The challenge has been the dearth of new ideas about how to rehabilitate them. A better understanding of the brain offers new ideas. For example, poor impulse control is characteristic of many prisoners. These people generally can express the difference between right and wrong actions, and they understand the disadvantages of punishment—but they are handicapped by poor control of their impulses. Whether as a result of anger or temptation, their actions override reasoned consideration of the future.

If it seems difficult to empathize with people who have poor impulse control, just think of all the things you succumb to against your better judgment. Alcohol? Chocolate cake? Television? It’s not that we don’t know what’s best for us, it’s simply that the frontal-lobe circuits representing long-term considerations can’t always win against short-term desire when temptation is in front of us.

With this understanding in mind, we can modify the justice system in several ways. One approach, advocated by Mark A. R. Kleiman, a professor of public policy at UCLA, is to ramp up the certainty and swiftness of punishment—for instance, by requiring drug offenders to undergo twice-weekly drug testing, with automatic, immediate consequences for failure—thereby not relying on distant abstraction alone. Similarly, economists have suggested that the drop in crime since the early 1990s has been due, in part, to the increased presence of police on the streets: their visibility shores up support for the parts of the brain that weigh long-term consequences.

We may be on the cusp of finding new rehabilitative strategies as well, affording people better control of their behavior, even in the absence of external authority. To help a citizen reintegrate into society, the ethical goal is to change him as little as possible while bringing his behavior into line with society’s needs. My colleagues and I are proposing a new approach, one that grows from the understanding that the brain operates like a team of rivals, with different neural populations competing to control the single output channel of behavior. Because it’s a competition, the outcome can be tipped. I call the approach “the prefrontal workout.”

The basic idea is to give the frontal lobes practice in squelching the short-term brain circuits. To this end, my colleagues Stephen LaConte and Pearl Chiu have begun providing real-time feedback to people during brain scanning. Imagine that you’d like to quit smoking cigarettes. In this experiment, you look at pictures of cigarettes during brain imaging, and the experimenters measure which regions of your brain are involved in the craving. Then they show you the activity in those networks, represented by a vertical bar on a computer screen, while you look at more cigarette pictures. The bar acts as a thermometer for your craving: if your craving networks are revving high, the bar is high; if you’re suppressing your craving, the bar is low. Your job is to make the bar go down. Perhaps you have insight into what you’re doing to resist the craving; perhaps the mechanism is inaccessible. In any case, you try out different mental avenues until the bar begins to slowly sink. When it goes all the way down, that means you’ve successfully recruited frontal circuitry to squelch the activity in the networks involved in impulsive craving. The goal is for the long term to trump the short term. Still looking at pictures of cigarettes, you practice making the bar go down over and over, until you’ve strengthened those frontal circuits. By this method, you’re able to visualize the activity in the parts of your brain that need modulation, and you can witness the effects of different mental approaches you might take.

If this sounds like biofeedback from the 1970s, it is—but this time with vastly more sophistication, monitoring specific networks inside the head rather than a single electrode on the skin. This research is just beginning, so the method’s efficacy is not yet known—but if it works well, it will be a game changer. We will be able to take it to the incarcerated population, especially those approaching release, to try to help them avoid coming back through the revolving prison doors.

This prefrontal workout is designed to better balance the debate between the long- and short-term parties of the brain, giving the option of reflection before action to those who lack it. And really, that’s all maturation is. The main difference between teenage and adult brains is the development of the frontal lobes. The human prefrontal cortex does not fully develop until the early 20s, and this fact underlies the impulsive behavior of teenagers. The frontal lobes are sometimes called the organ of socialization, because becoming socialized largely involves developing the circuitry to squelch our first impulses.

This explains why damage to the frontal lobes unmasks unsocialized behavior that we would never have thought was hidden inside us. Recall the patients with frontotemporal dementia who shoplift, expose themselves, and burst into song at inappropriate times. The networks for those behaviors have been lurking under the surface all along, but they’ve been masked by normally functioning frontal lobes. The same sort of unmasking happens in people who go out and get rip-roaring drunk on a Saturday night: they’re disinhibiting normal frontal-lobe function and letting more-impulsive networks climb onto the main stage. After training at the prefrontal gym, a person might still crave a cigarette, but he’ll know how to beat the craving instead of letting it win. It’s not that we don’t want to enjoy our impulsive thoughts (Mmm, cake), it’s merely that we want to endow the frontal cortex with some control over whether we act upon them (I’ll pass). Similarly, if a person thinks about committing a criminal act, that’s permissible as long as he doesn’t take action.

For the pedophile, we cannot hope to control whether he is attracted to children. That he never acts on the attraction may be the best we can hope for, especially as a society that respects individual rights and freedom of thought. Social policy can hope only to prevent impulsive thoughts from tipping into behavior without reflection. The goal is to give more control to the neural populations that care about long-term consequences—to inhibit impulsivity, to encourage reflection. If a person thinks about long-term consequences and still decides to move forward with an illegal act, then we’ll respond accordingly. The prefrontal workout leaves the brain intact—no drugs or surgery—and uses the natural mechanisms of brain plasticity to help the brain help itself. It’s a tune-up rather than a product recall.

We have hope that this approach represents the correct model: it is grounded simultaneously in biology and in libertarian ethics, allowing a person to help himself by improving his long-term decision-making. Like any scientific attempt, it could fail for any number of unforeseen reasons. But at least we have reached a point where we can develop new ideas rather than assuming that repeated incarceration is the single practical solution for deterring crime.

Along any axis that we use to measure human beings, we discover a wide-ranging distribution, whether in empathy, intelligence, impulse control, or aggression. People are not created equal. Although this variability is often imagined to be best swept under the rug, it is in fact the engine of evolution. In each generation, nature tries out as many varieties as it can produce, along all available dimensions.

Variation gives rise to lushly diverse societies—but it serves as a source of trouble for the legal system, which is largely built on the premise that humans are all equal before the law. This myth of human equality suggests that people are equally capable of controlling impulses, making decisions, and comprehending consequences. While admirable in spirit, the notion of neural equality is simply not true.

As brain science improves, we will better understand that people exist along continua of capabilities, rather than in simplistic categories. And we will be better able to tailor sentencing and rehabilitation for the individual, rather than maintain the pretense that all brains respond identically to complex challenges and that all people therefore deserve the same punishments. Some people wonder whether it’s unfair to take a scientific approach to sentencing—after all, where’s the humanity in that? But what’s the alternative? As it stands now, ugly people receive longer sentences than attractive people; psychiatrists have no capacity to guess which sex offenders will reoffend; and our prisons are overcrowded with drug addicts and the mentally ill, both of whom could be better helped by rehabilitation. So is current sentencing really superior to a scientifically informed approach?

Neuroscience is beginning to touch on questions that were once only in the domain of philosophers and psychologists, questions about how people make decisions and the degree to which those decisions are truly “free.” These are not idle questions. Ultimately, they will shape the future of legal theory and create a more biologically informed jurisprudence.

David Eagleman is a neuroscientist at Baylor College of Medicine. This essay is adapted from his new book, Incognito: The Secret Lives of the Brain.
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