Volume of the Brain (IMAGE) Brown University Caption Voxel-based morphometry allows researchers to detect the volume of gray matter in different regions of the brain. Areas marked in red are associated with higher volumes in people exhibiting the personality trait of agentic extroversion. Credit White lab/Brown University Usage Restrictions with credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.