That makes a lot of sense, but isn't there still a preference for introversion or extroversion?
Greed just answered this well. In MBTI, there would still be a preference, though I/E might be close.
MBTI itself doesn't use ambiversion.. it would describe someone as "slightly expressed introvert" or "slightly expressed extrovert" instead.
Outside of MBTI, introversion/extroversion is a gradient, and ambiversion can be defined as "somewhere around the middle," not necessarily dead center. Based upon where one falls on the gradient, they are defined as an extrovert or an introvert. Ambiversion takes the same scale and dividing it into three parts rather than two. To use two categories would lump "slight introvert" in with "strong introvert"; to use three would lump "slight introvert" and "slight extrovert" together.
In some instances, it might be useful to include ambiversion. In others, such as defining function preferences, it wouldn't be.
"Ambivert" is probably more of a useful descriptor for someone who doesn't know which side of the introvert/extrovert scale he falls on.
Here is a new page listing the APS temperaments (the system I discuss), and there are a total of 17.
Pastoral-Counseling-Center
Compulsives are the extremes in both expressiveness and responsiveness. The pure extroverts or introverts, and/or directives or informatives. Phlegmatic and the hybrid temperaments that begin with "Phlegmatic" are your "ambiverts", in that they express moderately ("e" score of 4 or 5). However, they are still divided as to leaning on the E or I side (depending on the temperament Phlegmatic is blended with, which will either be on the E or I side; like Phlegmatic Melancholy {I} vs Phlegmatic Choleric {E}). Directly in the center would be a score of 4.5, which is not used. So even with the ambiversion recognized in this system, either I or E will still be preferred.
The hybrid temperaments that end in "Phlegmatic" are those that respond moderately (with high R "responding as an extrovert" and low R "responding as an introvert", and it is the same thing as far as the division of responding as an ambivert in favoring one or the other.
The pure (and compulsive) Choleric and Supine can also be seen as the other kind of ambiversion, as one expresses as an extrovert, but responds as an introvert, and the other responds as an introvert, but responds as an extrovert. The descriptions on this page even say the Supine "Is an extrovert, although he/she appears to be an introvert", and you can see it described as approaching very few people for interaction (which most people define introversion as), yet the high "want" is a kind of extroversion. (Perhaps this might explain all of these reported ENP's who seem introverted). I believe this temperament corresponds to Enneagram 6, which in that system, appears to be regarded as the ambivert, (while 9 (Phlegmatic) is regarded as an introvert, as it was an all the other temperament systems. On this page, for Phlegmatic, it says "Extrovert/introvert - relates well to tasks, systems and ideas and also relates well to people and is able to socialize when the need arises").
