Social science counts for these, but only sometimes.
I found this study today in which they concluded that extraverts have higher activity in their brains when smelling pleasant odors than those who do not self-report being extraverts.
Positron emission tomography (PET) was used to get images of participants’ brains (particularly the regional cerebral blood flow, or rCBF) as they were exposed to pleasant and unpleasant olfactory stimuli. Following this, participants completed the NEO Five-Factor Inventory, the results of which the researchers examined to see which participants were self-reported extraverts and which were not. The goal of the study was to see if there was an association between extraversion and rCBF, mainly because many psychologists feel that extraversion as it is currently defined is not the best way to describe exactly what it entails, as previous studies have shown that it more fundamentally represents a trait related to a bio-behavioral approach system that controls motivation.
So the study showed what they were looking for—higher extraversion scores were associated with greater activation in the amygdale and occipital cortex when exposed to pleasant odors. The authors also stated that the difference between how extraverts and introverts respond to such stimuli may also suggest that depression may be associated with decreased activation in certain parts of the brain (like the amygdale) when exposed to certain stimuli, since extraversion is negatively correlated with depression and other depressive disorders (I find this connection a bit fuzzy, but okay, sure).
And, you know, self-reported scores are always a little bit iffy, but whatev. I thought it was an interesting study.
Today’s song: Heather (Radio Edit) by Samin