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Study Correlates Increased Gray Matter with High Levels of Moral Reasoning

Last updated June 10, 2015

A study conducted at the University of Pennsylvania in collaboration with a researcher from Charité Universitätsmediz, Berlin, Germany, has found that people with advanced moral reasoning showed high gray matter content in areas of the brain that are involved in complex social behavior, conflict processing, and decision making, when compared with individuals with lower moral reasoning.


A study conducted at the University of Pennsylvania in collaboration with a researcher from Charité Universitätsmediz, Berlin, Germany, has found that people with advanced moral reasoning showed high gray matter content in areas of the brain that are involved in complex social behavior, conflict processing, and decision making, when compared with individuals with lower moral reasoning.

Moral psychology has intrigued philosophists and scientists alike for generations.  There are dedicated moral psychology labs that are currently working on unraveling the mystery behind “right vs. wrong and good vs. bad” decisions made by individuals. One major theory of moral development, developed by Lawrence Kohlberg, is that moral reasoning changed and evolved as people got older. The different stages of morality, in terms of maturity, are “pre-conventional,” “conventional,” and “post-conventional.”

The study being discussed here endeavored to understand whether individuals with different moral reasoning also have differences in brain structure. For this investigation, 730 students enrolled in the MBA program were recruited. The participants’ age was 27.1 (the structural brain maturation is completed by this age), and they had diverse educational backgrounds, with a minimum of 4 years of undergraduate education.

The participants were required to complete a “moral judgment test” online. The scores separated students with higher morality from the ones with lower morality. They were then requested to take the Defining Issue Test (DIT). The DIT consisted of complex moral predicaments (Example: assisted suicide). Based on the DIT, 67 students were chosen for final MRI studies. These 67 students represented different schema types (levels of moral development). The subjects were also classified as belonging to one of the following personality types:

  • Extraversion
  • Agreeableness
  • Conscientiousness
  • Neuroticism
  • Openness to Experience

Along with all the testing, brain structure was also analyzed using MRI.

The study results showed that:

  • ·There were higher scores in “openness to experience” and lower scores in “neuroticism” in participants who were at the post-conventional (mature) level of moral development
  • Women scored less than men in self-esteem and sense of control
  • Study subjects who were at the post-conventional level of moral reasoning showed higher gray matter volume in the prefrontal cortex of the brain than those who had not achieved that level of moral maturity
  • By implication, there was a correlation between post-conventional thinking and gray matter volume

The senior author of the study, Dr. Hengyi Rao, Assistant Professor of Cognitive Imaging in Neurology and Psychology at Perelman School of Medicine (University of Pennsylvania), says in the Penn Medicine News Release, “This research adds an investigation of individual differences in moral reasoning to the expanding landscape of moral neuroscience.” Dr. Rao further adds, “The current findings provide initial evidence for brain structural difference based on the stages of moral reasoning proposed by Lawrence Kohlberg decades ago.  However, further research will be needed to determine whether these changes are the cause or the effect of higher levels of moral reasoning.”

Written by Mangala Sarkar Ph.D.

Primary References:

High Levels of Moral Reasoning Correspond with Increased Gray Matter in Brain. (n.d.). Retrieved June 8, 2015, from http://www.uphs.upenn.edu/news/News_Releases/2015/06/rao/

Prehn, Korczykowski, Rao, Fang, Detre, & Robertson. (2015). Neural Correlates of Post-Conventional Moral Reasoning: A Voxel-Based Morphometry Study. PLOS ONE.

Retrieved June 8, 2015, from http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122914

Additional Reference:

Kohlberg - Moral Development | Simply Psychology. (n.d.). Retrieved June 8, 2015, from http://www.simplypsychology.org/kohlberg.html 

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: June 10, 2015
Last updated: June 10, 2015