How we change what others think, feel, believe and do
Arm body language
The arm is an interesting appendages with a ball at the top, a hinge in the middle, and with a rather complex toolset at the end.
Watch also for arms held still -- this is often the first place the deceiver starts when trying to control body language (they may even hold one arm with the other to keep them both still).
Arms are clever expanding devices that can make us bigger or smaller, reaching out without having to move the rest of our body.
They can extend towards the other person, either in threat or a more friendly way. Moved directly and quickly they threaten. Curved and moving more slowly they may offer comfort.
The can also extend laterally, sometimes as a part of a body-expanding 'I am big' display that can signify confidence or perhaps aggression.
Arms are used as a part of shaping as we wave them around and carve out the world. They are an adjunct to our words as we literally show other people how big the fish was or how small the child is.
When we are excited or confident, we may wave our arms about like windmills. When we are less confident, our shaping is smaller and closer to the body.
This waving of arms needs control and a person who bangs their hand on something may indicate clumsiness.
Raising the arms lifts something up. Done rapidly, it throws things into the air. With both arms, it exaggerates it further. A typical two-arm-raising gesture is frustration, as everything that is weighing the person down with confusion is thrown up into the air. Coupled with a shrug it indicates confusion ('I don't know!!').
Arms can be like weapons. They can symbolize clubs and spears as they strike out at imaginary foes. They can also be defensive, blocking and sweeping away attacks. In martial arts arms can be used to block and strike and this is reflected in how they may be used in communication.
Arms can act as the doorway to the body and the self. When they are crossed, they form a closed defensive shield, blocking out the outside world. Shields act in two ways: one is to block incoming attacks and the other is a place behind which the person can hide and perhaps not be noticed.
Crossed arms may thus indicate anxiety which is either driven by a lack of trust in the other person or an internal discomfort and sense of vulnerability (that may, for example, be rooted in childhood trauma).
The extent of crossing indicates how firmly closed the person is. This may range from a light cross to arms folded to arms wrapped around the person. An extreme version which may indicate additional hostility is a tight close with hands formed as fists. If legs are crossed also then this adds to the signal.
The hands in an arm-cross may also be used to hold the person in a reassuring self-hug, for example holding upper arms in a folded-arms position or wrapped around the torso, holding the sides. If the thumbs are up, this may indicate some approval or agreement with what is being said.
Crossed arms, especially when holding one another can show the person to be trying to keep themselves still. This can be to suppress any signals. It may also indicate repressed anger (I have to hold myself to prevent myself hitting you). In some cultures it also signals that the person is holding themself still so they can pay greater attention to you (and is hence a compliment).
Crossed arms, especially in a folded position can just mean the person is feeling comfortable, especially if there is little tension elsewhere in the body. Comfort indicates a lack of fear which may come from being with friends or may be because they feel sufficiently powerful to handle any attacks as they appear. Folded arms with a little more tension may indicate that the person is feeling judgemental.
When arms are not crossed, they expose the torso and the person, making them more vulnerable. This signifies comfort that often indicates trust. It can also be power position that dares the other person to attack whilst knowing that the other person dare not.
Crossed arms is a very obvious signal and if you do it in front of other people they will likely feel rejected and respond accordingly (including not agreeing with you).
Note that not all crossed arms are defensive, for example when the person is relaxed (as indicated above). Crossed arms are also used when the person is cold (this is typically done with hands tucked under armpits to keep them warm).
A common method sales people use with a customer in order to break the customer's crossed-arms closed position is to give the person something to hold or otherwise ask them to use their hands.
Reaching forward to the other person can be quite scary for them as you could attack them, and a sudden thrust forward can indeed be an aggressive signal, especially if the hand is pointing or shaped as a fist.
Reaching forward can also be an offer of support or affection, seeking to touch and join with the other person.
When arms are thrust forward, they are the first thing that may be grabbed or attacked. When a person feels defensive they may pull back their arms out of harm's way. This may even extend to putting them behind the back.
When arms are held behind the back, they are hidden from view. This may be because they have hidden intent and are concealing what may otherwise be a threatening signal.
Arms back exposes the torso, which creates vulnerability. This can signal submission (go on, you can hit me) or comfort (I know you won't hit me). The reason for comfort can either be because the person is with friends, or that they feel sufficiently powerful that they are confident that others will not attack them.