Does the size of your brain — or, more specifically, different regions of it — say anything about your personality? According to a new study, maybe.

Using magnetic resonance imaging and personality questionnaires, Colin DeYoung, a University of Minnesota psychology professor, and his colleagues investigated the biological basis of what psychologists know as the Big Five personality traits: extroversion, agreeableness, conscientiousness, neuroticism and openness/intellect. Their three years of research showed that certain brain regions had significantly different sizes depending on the self-reported strength of a particular personality trait.

Researchers used MRIs to compare the brains of the 116 healthy adults to the “reference brain” of a person whose personality traits seemed average, according to an article published in the June issue of Psychological Science. Using computer software, DeYoung said researchers “stretched or squished” individual brain scans to match them with the reference image, and then noted the size of the different regions of each brain.

MRI scans of self-described extroverts revealed a significantly larger medial orbitofrontal cortex, the area just above and behind the eye socket. This area is involved with keeping track of rewards, researchers said.

The posterior cingulate cortex and superior temporal sulcus were larger in people who identified themselves as having many characteristics associated with agreeableness. That area is associated with understanding the actions and mental states of others, researchers said.