We now see that our personalities become fixed at a rather early age; some of us can, indeed, change our types (previous post), but it’s somewhat hard.  …  Most of us attributed these things to how  neurotransmitters and hormones affect our brain centers.  Yet, we also know that certain parts of the brain are associated with different behaviors.  The medial orbitofrontal cortex is involved with rewards (as is the neurotransmitter dopamine); other regions are associated with threat response; still others with negative effects and punishment; lateral prefrontal cortex deals with planning and voluntary behavior; and, there’s a region associated with  examining the mental states of others.

Given these facts, a group of researchers (lead author is Colin DeYoung) at the Universities of Minnesota and Toronto, Yale, and the Mind Research Network searched to see if the shape of people’s brains was associated with personality.  They examined 116 volunteers who filled out questionnaires (i.e., self-evaluation); they were then subjected to MRI (brain imaging test).  The researchers used computer manipulation to determine the relative sizes of various parts of the brain.

The questionnaires were evaluated using the CANOE (conscientiousness, agreeableness, neuroticism, openness/intellect, and extroversion) characterization of personality.   By comparing these results with the brain imaging tests, they were able to find a correlation between relative brain sizes and personality. The results were published in Psychological Science.

The research does NOT indicates that if one has a larger lateral pre-fontal cortex, he or she would grow to be conscientious. It is possible that, given our personality being set by around age 7, this part of our brain grows in size as we mature and continue our development. Other personality types were associated with different brain area sizes.    A larger orbito-frontal complex was associated with extroversion.  People who exhibit neuroses (depressing or negative thoughts) have smaller medial prefrontal cortices (the emotion regulating portion of the brain).  Agreeable types had larger portions of the brain that deals with examining the mental states of others. Those demonstrating openness (creative types) had no special characteristics.

The good news is that these studies seem to indicate that we will not be able to select genetically for the child we want!  Our personality traits are related to scores or hundreds of different genes.  And, looking for size of brain regions at birth (or prenatal) won’t work either- we probably grow the parts of the brains we need to exhibit our personalities.

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