Anthroposemiotics is the field dedicated to understanding how people communicate. This involves communication with one’s self (intrapersonal) and with others (interpersonal).
What we know as ‘body language’ is a subsect of intrapersonal expression. It consists of body posture, gestures, facial expressions and eye movements. The interpretation of these signals is almost entirely subconscious.
According to a 1960s study by Albert Mehrabian, any verbally-communicated message regarding one’s feelings or attitudes can be broken down like this:
38% vocals (volume, pitch, rhyme, etc.)
55% body movements (mostly facial expressions)
This means that up to 93 PERCENT of what we say is interpreted not by the content of the words themselves, but by how we say them and how we look when we say them.
Let that soak in a moment.
Source: You Say More Than You Think (Janine Driver)