> Introverts, whom experts say comprise about a third of the population...

Stuff like this implies it's clear-cut. But I don't even know whether I'm an introvert or an extravert. I strongly identify with traits at both ends of this supposed spectrum. And I don't see myself as someone who 'swings' between the two, nor do I see my traits as conflicting. I just don't identify with this spectrum at all. And I can't confidently place other people on it either. It feels willfully vague and pseudosciencey to me.