Killer’s Brain

He further divided the murderers into two groups of “affective” and “predatory” killers to study the differences, if any, in their brains. (Affective being those who kill on impulse; predatory being those who kill with prior intent.) Although some of them could not be strictly assigned to either one of the groups, Raine was able to assign 15 of the 41 murderers to the predatory group and 9 to the affective group. He found that while affective killers had poor pre-frontal functioning, predatory killers had intact prefrontal activity. Both groups had higher than normal activity in the sub-cortex region of the brain, which is a deeper, more primitive part of the brain.

“This is the part of the brain that gives rise to more aggressive feelings and may stimulate aggressive behavior,” says Raine. “The one difference between the two groups of killers is that the impulsive, emotional individuals [affective killers]—who have a lot of emotional, aggressive feelings—are not able to control their behavior because they have poor frontal function.

In contrast the planned, regulated killers [predatory killers] may feel aggressive and angry. But they have sufficient pre-frontal resources to be able to regulate, control and channel their aggressive behaviors into activities that may give them a lot of pleasure.” And according to Raine, since they carefully plan their activities, it is harder to nab the predatory, cold-blooded killers.

Early Brain Development

“Its likely that the seeds of violence are sown very early on in life,” says Raine. “Of course social factors are also critically important. We know for example that individuals who have suffered birth complications but who are also rejected by their mother in the first years of life are especially likely to grow up to be violent criminal offenders.”

Raine also points out that they don’t know for certain whether the poor brain functioning they find in killers was there before the homicide, whether it was there early in life and predisposed them to crime, or whether living a violent way of life actually caused the brain damage. “Nevertheless”, he says, “there is increasing evidence from child brain studies that suggests that poor brain functioning can indeed cause a predisposition to violent and anti-social behavior.” But there are no studies as yet proving that poor brain functioning early in life is a pathway to later violence.

He believes that early enrichment of the lives of those with a biological predisposition to violence may help to reduce violence in society in the future. But although they have ideas about what may be the root causes of violent behavior, he says, “at the moment it’s simply too early to apply those findings. We’ll be criticized for doing that. What we really need is a lot more research in this area, but research of the type that can ultimately be applied in practice so that we can do something about treating violent offenders in prison, and do something about taking juvenile delinquents off the street.”