Neuroscientists have taken a step closer to a physiological explanation of why some people work and play well with others. Two areas in the brain appear to have key roles in how people conform with social norms. These parts of the brain mature slowly, which may help explain why adolescents are less easily cowed by the threat of punishment than are adults.
All societies have social norms or widely shared beliefs about how people should behave in a given situation. But little is known about how the brain processes the possibility of punishment for violating these norms. To gain insight into this phenomena, a team led by Manfred Spitzer of the University of Ulm in Germany used a technique known as functional magnetic resonance imaging to determine which areas in the brain were most active in 23 men making decisions that could result in social punishment.
The men were given money and asked to decide how much of it to share with someone else. The men knew that the other person could punish them by reducing some or all of their money if they decided the initial shared amount was unfair. Several areas of the men's brains were active, but the regions that seemed to be the most involved in how the men made their decisions included the lateral orbitofrontal cortex and the right dorsolateral prefrontal cortex, the researchers report in the 4 October issue of Neuron. These areas, which reside near the front of the brain, have previously been associated with social moral judgments.
The brain regions showed less activity when a computer was meting out the punishment, indicating the prospect of disappointing or angering the other person may be more important than the fear of the punishment itself in activating these areas. "It's very convincing," says Daniel Hommer, a neuroscientist at the National Institutes of Health in Bethesda, Maryland.
The findings could have implications for how children are handled by the criminal justice system because the identified brain regions do not fully develop until adulthood, Spitzer says. "This implies that the threat of punishment may not work in these younger people as it supposedly does in people with fully matured brains," he says. "It appears to be a bit like punishing the blind for not seeing." The results also could lead to a better understanding of psychopathic behavior. Spitzer plans to study prison inmates with various types and degrees of personality disorders to find out if they have less activation in these brain regions in response to potential punishments.
Marcus Raichle, a neurologist at Washington University in St. Louis, says the study suggests it may one day be possible to predict how a particular person might behave by scanning his or her brain. "We may not be able to pull out individuals now," Raichle says, "but the mere suggestion that you might be able to do that is important."
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