How we change what others think, feel, believe and do
Mouth body language
Generally speaking body orifices are not terribly desirable as they can cause problems such as being entries for disease or can be snagged on passing bushes. The mouth is perhaps the ultimate multi-function orifice as we use it for communicating, breathing and eating.
The mouth is involved in the expression of many different emotions, from happiness to sadness, from fear to disgust. In emoting, the lips play a major role in creating visible shapes, with able backup from the teeth and tongue.
Studies have shown that people who are good at identifying emotions tend to watch the other person's mouth more than their eyes, as has previously been thought.
We usually breath through the nose, but when we need more oxygen we use the mouth to gulp in greater amounts of air.
A person who is frightened or angry by the fight-or-flight reaction may well open their mouth to get more oxygen in preparation for combat or running away. This may also involve breathing faster (panting).
Stressed breathing may even include gulping air and blowing it out. At worst a person may hyperventilate, breathing too fast and becoming dizzy, even to the point of collapse.
A hot person also pants hard. With typical the red face, this can be mistaken for anger (or vice versa).
Yawning is a process of taking a deep gulp of air as a quick 'pick-me-up' and often indicate a person who is tired or bored.
A short, deep, exhaling sigh, can indicate sadness, frustration or boredom.
Short inhalation, particularly in a sequence, can be like silent sobs and hence be an indicator of deep and suppressed sadness.
Slow, deep breathing, sometimes with slightly parted lips, may indicate someone who is relaxing or meditating. With closed eyes, they are seldom aware of what is going on around them and this may be done as an escape.
The mouth sends additional signals when it is speaking.
If the mouth moves little, perhaps including incoherent mumbling, this may indicate an unwillingness to speak, for example from shyness or from a fear of betraying themselves.
A mouth that moves a lot during speech can indicate excitement or dominance as it sends clear signals that 'I am speaking, do not interrupt!'
Careful shaping of words can also indicate a person with auditory preferences or a concern for precision and neatness.
Fast speakers are often visual thinkers who are trying to get out what they are seeing. They may also be looking upwards.
Slow speakers may be deep thinkers who are being careful about finding the right words. They may also have an auditory preference as they carefully enunciate each word.
The mouth is also used for eating, and the way people eat can tell things about them.
A well-mannered person opens their mouth the minimum to put in a moderate amount of food and keeps it closed whilst carefully chewing each mouthful. They also do not speak when they have food in their mouth.
On the other hand, an uncouth person gobbles large mouthfuls and opens their mouth as they chew and talk at the same time.
In a curious reversal, snobbish gourmands who take great pleasure in eating may do it noisily as an expression of pleasure. This may also be a cultural variable and in some places noisy eating is not only acceptable but also desirable.
People who chew smaller amounts at the front of their mouth are like children whose molars have not developed and may be timid.
People who chew for a longer time may be chewing on ideas at the same time.
When people slide their jaw sideways when they eat are grinding the food. this may also be pensive.
As with eating, drinking may be done in a polite way, sipping smaller amounts and swallowing noiselessly. It may also be done with loud glugging and followed by equally distasteful burping -- although again, in some cultures this is a desirable expression of pleasure.
Someone who is slooshing their drink around their mouth may well be thinking and deciding.
Sometimes the hand is used to cover the mouth. In polite society, exposing the inside of your mouth may be considered rude, so the hand is used to politely cover a yawn.
The hand is also used to conceal the mouth when it will betray emotions that may be undesirable. Thus we put our hands over impolite giggles and smirks, and we may do this to hold back from telling the truth.
Covering the mouth may also be a reason for hiding a yawn. We also cover the open mouth of surprise and the downturned mouth of sadness.
Smiling indicates pleasure, either that you are generally happy and are enjoying the other person's company or that you are amused by something in particular, such as a joke.
A full smile engages the whole face, particularly including the eyes, which crease and 'twinkle'. A true smile is also known as the Duchenne smile, after the scientists who first described it in 1862. False smiles also tend to last for longer.
Smiling with lips only is often falsehood, where the smiler wants to convey pleasure or approval but is actually feeling something else. Long, tense smiles are characteristic of anxious people trying to ingratiate themselves ('Don't hurt me -- I'm nice!').
A genuine smile is often asymmetric and usually larger on the right side of the face. A false smile may be more symmetrical or larger on the left side of the face.
Lowering the jaw to show a D-shaped mouth can be a false smile as it is easy to do. It may also be a deliberate signal of amusement and and an invitation to laugh.
Smiling without opening the mouth, and particularly with lips firmly pressed together, may indicate embarrassment about unsightly teeth. It may also be a suppression of words ('I can see the funny side, but I'm not going to comment.').
A half-smile, on one side of the face, may indicate cynicism, sarcasm or uncertainty ('Sorry, I don't buy that idea.').
Smiling is also a sign of submission as the person effectively says 'I am nice and not a threat'.
Smiling in some cultures indicates a question or that you want the other person to speak.
Beyond smiling, laughter shows greater pleasure and happiness. Whilst smiling may happen over a longer period, laughter is a relatively brief affair, happening for a few seconds.
There are many variants on laughter and we all laugh differently, from the suppressed titter to the loud and uproarious belly-laugh. Louder and less suppressed laughter may indicate someone who is less self-conscious. It may also be used by a person who is trying to gain attention.
In general, women laugh at men they like whilst men like women who laugh at them ('It's working! She likes me.'). This can lead to a satisfying bonding mechanism.
'Funny' often gets equated to 'nice' and 'harmless' and the use of humor thus can a way of sending friendship signals. Laughing at risqué jokes is a sign of acceptance of the other person (the alternative is to criticize or otherwise censure them).
Laughing and smiling at the misfortune of others is often socially unacceptable although we often find this funny (Germans call this 'schadenfreude'). In such cases you may see suppressed grins and giggles as the person tries desperately to hide their feeling of amusement. Laughs, for example may get disguised as coughs and the person may turn away to hide their expression.
Yawning is opening the mouth wide and gulping in a large quantity of air. We do it when we are tired and blood oxygen is low.
Boredom can indicated by yawning, signalling that the other person is so uninteresting they are sending us to sleep, which makes it often impolite (also because it shows the inside of the body). This results often in the yawn being covered with the hand or concealed such as by turning the head or holding the mouth more closed than it actually want to be.
The gulping of air in yawning can also be in preparation for action and a stressed person may yawn more, or at least take some bigger breaths.
Sucking a finger is often an echo of doing this in childhood. Young children suck fingers or thumb as a breast substitute. This action is hence a comforter, done when the person is uncomfortable or stressed in some way. This can happen in general anxiety or specific situations such as when lying.
Variants on this include sucking or biting knuckles, the side of a hand or other parts of the body such as the lips or inner cheek. Sometimes a physical item is used as a substitute, such as a pen or pencil. Biting generally indicates greater stress than sucking.
Pillai, D., Sheppard, E., and Mitchell, P. (2012). Can People Guess What Happened to Others from Their Reactions? PLoS ONE, 7 (11) DOI: http://dx.doi.org/10.1371/journal.pone.0049859