I don't understand your question. That's how people express emotion, mostly. I'll trust you are not being argumentative: Facial expression - eyes (the muscles

I don't understand your question. That's how people express emotion, mostly. I'll trust you are not being argumentative: Facial expression - eyes (the muscles around them), mouth (smile, blank, frown, etc) - posture, legs, arms, etc etc etc. You can look disinterested, you can look like it's the best thing ever, or any other human emotion.