Addiction fundamentally changes the reward system in an addict’s brain, which means he or she no longer responds to the threat of punishment in the same way, says Nora Volkow, the director of the Institute on Drug Abuse at the National Institutes of Health in Bethesda, Maryland. “This explains why the threat of a judicial punishment cannot stop drug-taking,” she says.
That potential for change, even in adult brains, is why people like Eagleman advocate treatment over punishment. His team is running an ambitious programme to improve impulse control in drug addicts. “The brain is like a team of rivals, all of whom are trying to be in control,” he says. “There’s a battle between parts of the brain that want the drug and the parts that are engaged in long-term deliberative thinking and forgoing the drug.”
Eagleman and his colleagues are using real-time neuroimaging feedback to strengthen people’s short-term capacity to resist impulses. He places someone with a drug addiction in an fMRI scanner and shows her a picture of whatever it is she is trying to resist; cocaine, for example. At first, he asks her to allow the craving to proceed, and he measures her brain activity. On a screen inside the scanner, the volunteer watches a bar that represents her craving level. Then Eagleman asks her to try to force the bar to go down. “By squelching that craving, you are strengthening the frontal lobes, which allow you to override impulses,” says Eagleman. “Practicing this over and over means you then know how, even if you don’t quite understand it, to make that bar go down.”
This study is only just underway, and has yet to show if mental strengthening could be a more rational approach to treatment – and prevent habitual reoffending – than imprisonment alone. But it has its supporters. “Anything that can teach people how to control their impulses is a much more sensible way to deal with highly impulsive behaviour than just locking someone up,” says Mackintosh.
In moving towards legal systems that focus as much on treatment as on punishment, societies will nevertheless have to confront an uncomfortable truth, says Eagleman: retribution is built in to our systems. We don’t imprison people just to prevent them from committing a similar crime or to keep society safe, but to punish them and make them pay for what they did.
In the case of Grady Nelson, one of the jurors who voted to imprison him for life rather than execute him did so not because he was persuaded by the neuroscientific evidence of Nelson’s brain abnormality, but because he wanted him to live with the stigma of being a child rapist. It shows that human beings are hardwired for retribution, says Eagleman. “People will give their own resources to punish others even when they’ve not been affected themselves. Even if someone was driven to paedophilia because of a brain tumour, we’ll probably need a minimum amount of sentencing. Just extracting the tumour won’t slake the bloodlust of society.”