Excerpt from this article:
People use language in different ways, and those differences are a function of their personality. Our choices are spontaneous and unconscious but they do reflect who we are. Text mining studies have found associations between key words and major aspects of personality. The more frequently people use those words, the more likely it is that they display certain personality traits.
For example, extraverts talk about fun-related stuff: bars, Miami, music, party, and drinks. People with lower EQ are more likely to use emotional and negative words: stress, depressed, angry, and unfortunate. Narcissists talk about themselves–the number of self-referential words (e.g., “I,” “me,” “mine,” “myself,” etc.) is indicative of someone’s self-love and entitlement. Artistic and intellectual individuals use highbrow words, such as narrative, rhetoric, and leitmotiv.