Where do you think you fall on the introvert-extrovert scale? More than a variant, "extravert" is actually the original spelling that Jung used, which he chose because "extra" is a legitimate Latin prefix, while "extro" is not: http://blogs.scientificamerican.com/beautiful-minds/the-diff...

I'm pretty far on the introverted side, and would prefer spelling it "extraverted" although I'm aware that this is nonstandard in the US. I think this is because I tend to be more attentive to the rules of orthography than to common usage. I'd guess that extroverts tend to care more about social norms than while introverts are more comfortable with consistent rules?