Personalities come in all kinds. Now psychological scientists have found that the size of different parts of people’s brains correspond to their personalities; for example, conscientious people tend to have a bigger lateral prefrontal cortex, a region of the brain involved in planning and controlling behavior.
Psychologists have worked out that all personality traits can be divided into five factors, commonly called the Big Five: conscientiousness, extraversion, neuroticism, agreeableness, and openness/intellect. Colin DeYoung at the University of Minnesota and colleagues wanted to know if these personality factors correlated with the size of structures in the brain.
For the study, 116 volunteers answered a questionnaire to describe their personality, then had a brain imaging test that measured the relative size of different parts of the brain. A computer program was used to warp each brain image so that the relative sizes of different structures could be compared. Several links were found between the size of certain brain regions and personality.
C'mon, this is a joke, right? Below, a quick rundown of the nineteenth century pseudoscience of phrenology from Wikipedia:
Phrenologists believed that the mind has a set of different mental faculties, with each particular faculty represented in a different area of the brain. These areas were said to be proportional to a person's propensities, and the importance of the given mental faculty. It was believed that the cranial bone conformed in order to accommodate the different sizes of these particular areas of the brain in different individuals, so that a person's capacity for a given personality trait could be determined simply by measuring the area of the skull that overlies the corresponding area of the brain.Phrenology was a handy tool for racists. Favored personality traits corresponded remarkably with Caucasian high foreheads and other admired features. Certain physical types were held to be predisposed toward criminal behavior. I remember the narrative avatars of Charlotte Bronte, that sage high-foreheaded bigot, sizing up lovers and villains for organs of veneration, bumps of benevolence, intellect, etc.
I'm in no position to judge Dr. De Young's research. But I am very suspicious of claims to find a simple correspondence between physical features of the brain and personality type, as I am of research that purports to link various emotional experiences to specific brain activity.
For the record, that "big five" sounds pretty dicey, too.