There have been many studies on how non-verbal behaviour (body language such as facial expressions, gestures etc) impact communication.

Back in the 1950s, Dr Ray Birdwhistell was one of the first to suggest that no more than 30% to 35% of the social meaning of a conversation or an interaction is carried by words. (There were others before him but Dr B has by far the coolest name, so we like him best).

Today, there is a strong school of thought that, when we communicate, people pay attention to our words and actions as follows: