Physiology and tonality
In 1970 the American anthropologist Ray L. Birdwhistell published a book entitled Kinesics And Context based on his studies of human body motion in the context of inter-personal communication.
In this book Birdwhistell advanced the theory that human inter-personal communication requires the use of all the senses and that the words that we use to communicate with each other account for a mere 7% of our communication.
The next obvious question is, if our words make up only 7% of our communication, what makes up the other 93%?
According to Birdwhistell the tonality of our voice when we speak is responsible for 38% of our communication and a massive 55% of our communication is conveyed through our physiology - how we position and move our body during our communication.
Ever had a really difficult day, the kind where you feel like you should really have just thrown the alarm clock at the wall and stayed in bed?
During that really bad day when someone asks you how you're day is going you say - Oh yeah, I'm having a REALLY GREAT day, never better.
Taking the words (7%) at face value the person asking the question could easily believe that you were indeed having a really great day (demonstrating this in text works brilliantly because the words are all you have to go on, you have to imagine the rest).
However, when we consider the sarcastic tone of voice emphasising the words REALLY GREAT (tonality - 38%), the look of dismay on your face, drooping shoulders, drooping head and the huge sigh as you force the words out (physiology - 55%) it becomes evident once we have the full communication that the meaning of your communication is actually the complete opposite of the words that you used!
A key point to remember is that in this example physiology and tonality are heavily exaggerated for emphasis - in regular every day communication, shifts in physiology and tonality are far more subtle and often so subtle that they are outside of our conscious awareness.