People who are concerned with justice are swayed more by reason than emotion, according to a recent study.

Researchers from the University of Chicago department of Psychology and Center for Cognitive and Social Neuroscience found that some individuals react more strongly than others to situations that invoke a sense of justice - for example, seeing a person being treated unfairly, or with mercy.

"We were interested to examine how individual differences about justice and fairness are represented in the brain to better understand the contribution of emotion and cognition in moral judgment," lead author Jean Decety said in a statement.

For the study, researchers used brain scans to analyze the thought processes of people with high "justice sensitivity." Using a functional magnetic resonance imaging brain-scanning device, the team looked at what happened in the participants' brains as they judged videos depicting behavior that was morally good or bad. Then the participants were asked to rate on a scale how much they would blame or praise the actor seen in the video. People in the study also completed questionnaires that assessed cognitive and emotional empathy, as well as their justice sensitivity.

They found that study participants who scored high on the justice sensitivity questionnaire assigned significantly more blame when they were evaluating scenes of harm. They also registered more praise for scenes showing a person helping another individual, Decety said.

The brain imaging yielded surprises. During the behavior-evaluation exercise, people with high justice sensitivity showed more activity than average participants in parts of the brain associated with higher-order cognition. Brain areas commonly linked with emotional processing were not affected.

Based on their findings, Decety concluded that "individuals who are sensitive to justice and fairness do not seem to be emotionally driven. Rather, they are cognitively driven."

"Our results provide some of the first evidence for the role of justice sensitivity in enhancing neural processing of moral information in specific components of the brain network involved in moral judgment," Decety said.

The findings were recently published in the Journal of Neuroscience.