Moral reasoning linked to more gray matter in brain

Individuals with a higher level of moral reasoning skills have an increased gray matter in the brain, reveals a study.

Moral development research pioneered by psychologist Lawrence Kohlberg in the mid-20th century shows that people progress through different stages of moral reasoning as their cognitive abilities mature.

"The new study adds an investigation of individual differences in moral reasoning to the expanding landscape of moral neuroscience," said Hengyi Rao, research assistant professor in the Perelman School of Medicine at University of Pennsylvania.

To reach this conclusion, the team studied MBA students at the Wharton School of University of Pennsylvania.

"MBA students were ideal candidates for this work as the Wharton curriculum addresses issues of moral decision-making and reasoning," explained Diana Robertson, professor at Wharton School and an author of the study.

The team employed MBA students in the age group 24 to 33, past the age at which structural brain maturation is complete and were tested for their moral reasoning.

Students then underwent MRI scanning to investigate differences in gray matter volume between students who reached the post-conventional level of moral reasoning compared to those who have not reached that level yet.

Subjects also underwent personality testing and were placed into one of the following categories: neuroticism, extraversion, openness to experience, conscientiousness and agreeableness.

Analysis showed higher scores in openness to experience and lower scores in neuroticism for participants at the more advanced levels of moral development.

With regard to brain structure, the team observed increased gray matter in the pre-frontal cortex of the brain in subjects who reached the post-conventional level of moral reasoning compared to those who are still at a pre-conventional and conventional level.

In other words, gray matter volume was correlated with the subject's degree of post-conventional thinking.

The findings provide initial evidence for brain structural difference based on the stages of moral reasoning.

The research was done in collaboration with a researcher from Charite Universitatsmediz in Berlin, Germany.

The work was published in the journal PLOS ONE.