According to the MBTI it is not a spectrum; you have a preference for one or the other. This doesn't mean you can't or don't behave in ways outside your prefer

According to the MBTI it is not a spectrum; you have a preference for one or the other. This doesn't mean you can't or don't behave in ways outside your preference; we all do, everyday. It just means that, all other things being equal, you will lean toward extraversion or introversion. Also, please note that MBTI E/I does not equate to extraversion/introversion as it is known and understood by society at large.