Red Mars by Kim Stanley Robinson

Extroversion-introversion was one of the best-studied systems of traits in all psychological theory, with great masses of evidence fro many different cultures supporting the objective reality of the concept. Not as a simple duality of course; one did not simply label a person plainly this or that, but rather placed them on a scale, rating them for qualities such as sociability, impulsiveness, changeability, talkativeness, outgoingness, activity, liveliness, excitability, optimism, and so on. These measurements had been done so many times that it was statistically certain that the various traits did indeed hang together, to a degree that the  exceeded chance by a huge amount. So the concept was real, quite real! In fact psychological investigations had revealed that extroversion was linked with resting rates of low cortical arousal, introversion with high cortical arousal; this had sounded backward to Michel at first, but then he remembered that the cortex inhibit the lower centers of the brain, so that low cortical arousal allows the more uninhibited behavior of the extrovert, while the high cortical arousal is inhibitory and leads to introversion. This explained why drinking alcohol, a depressant which lowers cortical arousal, could lead excited and uninhibited behavior.

p. 195

Two points here. First, I always wonder about the science in these books. They are not called science fiction for nothing. Still, it has the tone of authority that makes it sound accurate. I also wonder how much of my approach to life, which I would put in the scientific/analytical bracket, comes from the stuff I read from an early age. Often it gave me a way to visualize the concepts I had learned. And that is part of the power of fiction. It allows us to see things in a new way, not just science, but also the human relationships that are at the heart of any great or even good story. We are testing out what might be. I once heard it said that that was why romantic comedies are such popular films - we are all trying to figure out the relationship game.

The second point has to do with the content. The character, Michel, thinks of these things in terms of suppression of the higher and expression of the lower. I sort of think of these things in Freudian terms. If there is higher critical arousal, then the super ego is given more power. The introvert does more thinking about stuff, not the knee-jerk reaction of the extrovert. The days are spent in thought because of the arousal. We don't do things because we keep thinking about it. I often think back to a high school reading - Milton's two poems, L'Allegero and il Penseroso. Once again the visual images have stuck with me all these years, even though the words are gone. I guess I could look them up. LOL