I've noticed there's a lot of overlap between the following words meaning "earnest" or "serious" when talking about a person:
- まじ
- 真面目{まじめ}
- 真剣{しんけん}
- 本気{ほんき}
- 正気{しょうき}: (This word really means "sane" I believe, but I'm including it as I think 「正気か?」 can translate to "are you serious?")
- 素直{すなお}: (I'm not sure whether this word meaning "honest" belongs here I but keep wondering what it's relationship to 真面目{まじめ} is when it means "obedient". I thought there might be some overlap in it's usage, e.g. 「素直な顔」 "obedient face" and 「真面目な顔」 "serious face". It could well be unrelated though.)
Would I be allowed to ask what the differences between these words are and when they're used?