In English I can tell my son: "Today I talked to Adrian", and he won't ask: "How do you know you talked to Adrian?" But in some languages, including Tariana, you always have to put a little suffix onto your verb saying how you know something - we call it "evidentiality". I would have to say: "I talked to Adrian, non-visual," if we had talked on the phone. And if my son told someone else, he would say: "She talked to Adrian, visual, reported." In that language, if you don't say how you know things, they think you are a liar.