When I was in high school, I took one of those free Myers-Briggs quizzes online--with the disclaimer and everything, that it isn't the full profile and so on et cetera, but fairly comprehensive. I remember, weirdly and possibly not accurately, that it was 99 questions (that might have been the Sorting Hat one. No, I definitely wasn't obsessed with taking personality quizzes, why do you ask?), and I scored as INTJ. For reference, that's Introvert, Intuitive, Thinking, Judging. This evening (in class no less! The professor even told us we could!), I played the Insight Game, and got . . . well, I got several possible results, since the answers for some of my categories were pretty close, but the ones that ring true from inside my head are ESFJ/ISFJ. For those of you playing along at home, that's a difference of up to THREE letters. Out of FOUR. (BTW, E=extrovert, S=sensory, F=feeling.)
I don't perceive myself as having changed much, by the way, from high school to college to graduate work--I'm a little more willing to talk with people I don't know and sometimes spontaneously decide to go to social events (two reasons why that's surprising: spontaneity and events. I have always liked hanging out with people and talking, but still don't really like parties). So why the huge change in how I view my personality, if I haven't really changed that much?
That other aspect of my personality would be the J, by the way. Its opposite is Perceiving, the characteristics of which are spontaneity, a hatred of routine, tendency to procrastinate and end up doing too much at the last minute. They hate making up their mind about anything (in fact, this is a major reason they procrastinate), and they tend to second-guess their decisions even after they are already committed. The only aspect in which this describes me is that I dislike making decisions (I rarely second-guess my decisions after making them though, and almost never seriously consider changing them), and I think that might be a girl thing rather than a personality thing. Or a girl-in-Western-society thing--feel free to discuss. I make snap decisions, I hate changing plans, I adore routine, and I find it much easier to schedule my time (even though that's sometimes hard) and do things in pieces than have to do entire projects at the LAST POSSIBLE SECOND OMG. So rigidity is a Thing in my life, and a bunch of T personality types have the word "rigid" in their descriptors, and you can totally see how I misapplied it, right? I never figured out, until this evening playing the Insight Game, that my rigidity comes less from an inflexible mind and more from an almost religious devotion to Schedule.
Third, Extrovert/Introvert. I am an extrovert in the most internal sense--being around people winds me up and energizes me rather than wearing me out. I am not a traditional extrovert otherwise; I'm not particularly outgoing, nor do I always need to be around a bunch of friends, nor for that matter do I make friends easily. But I find talking to be an easy and enjoyable activity, and I will never turn down a conversation even if I happen to be doing something else. The reason I identified so strongly as introvert in high school is a combination of that tendency to create a routine and never want to deviate from it for the rest of my life mentioned above, and being homeschooled in a family that is 3/4 introvert. Both of my parents and my sister all need time away from people to recover energy, so I learned not to bother people unless they showed signs of wanting to interact with me, and had that lesson drilled into me until I started college at 19. I learned it so well, in fact, that I don't remember when I first learned it.
Last of all, Sensory vs. Intuitive. I have no idea how I ever deluded myself into thinking I was intuitive. Yes, I'm an inventive, imaginative person--but all my imaginings stem from other people or my observations. I observe more intensely than I do anything else, with an insane eye for detail. There's nothing wrong with that, I know now--even for creative writers, it all falls flat without close attention to world-building and character detail, and my sweetie says I would have been an excellent actress with my ability to get inside people's heads and construct their stories from their actions. Maybe it's that I observe so well that I thought I just intuitively knew things--for example, in my teens I had a trait I called "emotional chameleon" (picking up what people around me are feeling and feeling the same way), which I trained out of myself as soon as I realized I had it. (It's very uncomfortable, being dependent on everyone around you being in a good mood.) Maybe it's just that the dividing line between intuitive and sensory is more arbitrary than most, and I in my practicality and care for details fall on the sensory side rather than intuitive in this emphasis, where the dividing line between the two would fall elsewhere in another, and I without moving would change sides.