Introversion: a personality tendency toward being inward-focused, reflective, and preferring small groups or solitude rather than large social settings.
面接で彼の内向性が話し方に表れていた。
His introversion showed in the way he spoke during the interview.
内向性と外向性は性格のスペクトラム（連続体）と考えられている。
Introversion and extraversion are considered points on a personality spectrum.
内向性の人は一人で集中して勉強するのが得意なことが多い。
People with introversion are often good at concentrating and studying alone.