Show my your amygdala size and I’ll tell you who you are! In a study by Omura, Constable & Canli in the November 2005 issue of NeuroReport (see abstract + links below), the sizes of the right and left amygdalae were compared to assessment of the levels of extraversion and neuroticism. The results indicated that the smaller your right amygdala is the more neurotic you are. A larger left amygdala correlated with being more extravert.
How long before your job application includes a mandatory brain scan? Well, as soon as there is only a correlation between amygdala size and personality inventory subscales then the personality subscales is cheaper to use. But psychological tests are prone to errors and the time of assessment. A brain scan is more objective, since your brain does not alter its shape (dramatically) from day to day. But the amygdala might not be the only place one could test. Depending upon the job we could add brain scans for working memory, visual perception, empathy and social reasoning. It might not be here just yet, but it might very well be within our reach to do this.
Using high-resolution magnetic resonance imaging and voxel-based morphometry in 41 healthy individuals, this study evaluated the association between the personality traits of extraversion and neuroticism, on the one hand, and individual differences in localized brain volume and gray matter concentration, on the other, with a special focus on the amygdala. Extraversion was positively correlated with gray matter concentration in the left amygdala, whereas neuroticism was negatively correlated with gray matter concentration in the right amygdala. Given that neuroticism is a risk factor for depression, our finding offers one explanation as to why prior structural imaging studies of depressed patients (which did not control for personality) produced conflicting findings. Furthermore, our data are consistent with the view that amygdala reduction seen in depressed patients precedes the onset of the disease, rather than being a consequence of the illness.