When I was in the Military, I spent some time teaching Body Language Analysis in interviewing and interrogation. This involved reading the subjects body language as well as using the interviewers/interrogators own body language to get the optimal results.
Research suggests the relative proportion of information is passed via three elements:
Verbal - 7% (what is said);
Vocal - 38% (how it is said); and
Non verbal - 55% (facial expression, posture, gestures).
In normal conversation, the verbal element is primarily used for passing the facts or opinions that a speaker wishes to convey to the listener. The vocal element is used to support the words and may also be used to support the non-verbal element which is used primarily for showing attitudes and feelings, though it can be a substitute for verbal messages, for example where there is a language barrier.
As you can see the non-verbal component, which is more commonly referred to as body language, is the single largest component of person to person communication.Each gesture is like a single word, and a word may have different meanings. It is only when the word is used in a sentence with other words that its meaning is fully understood. Gestures come in sentences/clusters and may indicate the truth about a person's feelings or attitudes.
We are generally unaware that posture, body movements and gestures can tell one story while the voice may be telling another. Suffice to say that if you work at understanding body language the better chance you have at understanding what is really being said.
So how does one transfer this information into their writing? Firstly, using body language indicators is a great way of 'showing' the information instead of 'telling' the reader what is happening. And, when using dialogue, accompany it with some sort of physical movements. Let's face it, do you just sit or stand still when talking to someone? Do you stand closer to someone you are more comfortable with? Do you touch the arm of someone you care for just before speaking with them?
A word of warning though. Don't have a physical movement at the end of each dialogue tag. Remember, everything we write must add value to the story somehow.
If you have a particular question on body language that you would like me to blog about, just let me know.