All I knew back then, was from the discussion my father gave one time about introversion and extroversion. And then, I noticed among the extroverts, that some were more light and airy, and others were more serious. For introverts, it was harder to tell the difference. He also discussed "head" vs "heart" another time. And he favored "concrete" reality over too much "abstraction".
When you mention some extroverts being light and airy while others are more serious you must mean the difference between EPs and EJs.
Back on topic, I was about 22, now going on 27, roughly five years with the knowledge of being a INTP.