"Body language", formally called non-verbal communication and subject of the study of Kinesics, consists of all forms of perceived or supposed communication that are not verbal; that is, do not use language. Examples are facial expression, gestures, postures, movements, voice inflections and intonations, behaviours and more. Non-verbal aspects of spoken language such as timing and articulation, as well as non-verbal aspects of written language, belong to this realm too, even though the popular term "body language" does not explicitly cover them (non-verbal aspects of written language are a field of study in their own and will not be further discussed in this article).
Expression and interpretation of non-verbal messages are principally unconscious, which suggests the evolutionary origin of body language lies before the advent of current human awareness. It may have developed in the process of mate selection, and to establish hierarchy and maintain order in groups of animals. However, persons who professionally deal with people face-to-face or over the phone often have learnt to become aware of the effect of perceived non-verbal communication and actively use it to manipulate their clients, students, employees, or citizens. (The word "unconscious" is preferred to "subconscious" in this article.)
The contents of the non-verbal is normally of an emotional or instinctive nature and supposedly helps the involved parties to know what behaviour is expected from or appropriate for them in the current social context. The non-verbal component of art, music, literature, theatre and rhetoric though is often more of an intellectual or intuitive nature.
Psychologists and anthropologists claim that body language constitutes the majority of human communication, estimates varying between 60 and 93 percent. Also, interpreted non-verbality appears to be dominant over language; if one perceives a verbal and a non-verbal message at the same time, one involuntarily believes the non-verbal even when it contradicts the verbal one.
Use and interpretation of body language vary across cultures; perhaps apart from a simple smile, each and every supposed non-verbal expression is taken differently by different peoples. And there is variation across personality types; non-verbal communication is greatly reduced, absent, or deviant in persons with high introversion, schizoid, Aspergoid or autistic features, or some forms of schizophrenia. In short, it is not a clearly written-out message but a drop of ink wherewith the interpreter unawarely writes one's own. A walking Rorschach test onto which each unconsciously projects one's own shadows and allows them to override any accompanying verbal message.
Obviously, body language is one of the major causes of confusion, misunderstanding, conflict, and fight between humans. As apes it served a purpose. Now we have invented language, paper, pen, and ink to express our thoughts. Yet what do we do most of the time? We hand them over and say 'You write my message to you'. Small surprise we are misunderstood. Clearly, body language must be eliminated from modern communication and left to the apes. We must learn to use real language exclusively to express ourselves and, the hardest part, to interpret only the verbal component of whatever is being said to us while ignoring the apparent non-verbal one. In fact, we must learn to accept that the phenomenon of "reading between the lines", or interpreting non-verbal meaning into a person's communication, is a form of psychosis; that the perceived non-verbal message is imaginary, delusional, or hallucinatory, exists only on the side of the interpreter. That it is a species of eisegesis, of hineininterpretieren.
The latter is so hard because hallucinatorily or delusionally perceived non-verbal signals go straight to the unconscious, surpassing aware interpretation. And what thus enters the unconscious acts as suggestion, which explains non-verbality's dominance over the verbal. A suggestion given to a hypnotized subject may cause the subject to ignore any later instructions contradicting it (whether hypnosis is a true phenomenon does not matter here [it is not, in fact]; relevant is that suggestion is a true phenomenon). This also explains why those who are most inclined to go by the (delusional) non-verbal component of what is being said are typically the highly suggestible, the empathic, those who easily let their mind state be determined by others. These are also the ones with narrow associative horizons, the ones who are procreative rather than creative. On the other hand, those devoid of or blind to active or passive non-verbality tend to be creative rather than procreative.
Exactly how to rid ourselves of this plague is a riddle yet to be solved. At the moment we can only speculate; perhaps verbal education as in this article helps. Or, a more imaginative and powerful method that would reach exactly those who need it most: A universal non-verbal symbol that goes directly to the unconscious and says "Mind the verbal message only!"
A remark has been made that roughly goes as follows: "If, as you say, persons who professionally deal with people often learn to become aware of the effect of perceived non-verbal communication, and purposely use it to manipulate their clients, students, employees, or citizens, does that not show that non-verbal communication is a true phenomenon after all, rather than a delusion, and that objective interpretation of it is possible?"
The reply to this is: No. It only shows that there is interpretation in the non-verbal plane going on on the receiving end. It does not prove, or even suggest, that people in general are unawarely broadcasting meaningful non-verbal messages which can be decoded objectively. It must be realized that the purposeful users meant here are deliberately broadcasting artificial "non-verbal" messages, which therefore are not true non-verbal messages. This artificial non-verbality is awarely tailored by the "sender" to achieve certain effects on the side of the interpreter, based on how one expects the latter to respond. It concerns things like giving a firm handshake, making eye contact, mirroring the other's body position, and so on (note that these techniques should be seen as related to the use of background music and scents to influence the audience in stores or other public buildings). There is no question of that people in general naturally and spontaneously do all of these things, and that they indeed mean what some psychologists like us to think they mean.
It has been suggested that a function of non-verbal communication is to detect if someone is lying, and that therefore we can not do without it. The reply thereto is that while sophisticated equipment like high-speed cameras and lie detectors can tell with a reasonable probability whether a person speaks the truth, there is absolutely no chance that humans can do so with the naked eye and intuitively. Of course, one may have the impression, or instinct, that the other is lying, but that may just as well be a delusion as reality. Grave injustice has been done to many by belief in prejudices like "people touch their nose while telling a lie", "people look away while lying", and "people blink a lot while lying". Such is third-rate psychology. There exist no universal unequivocal signals that betray insincerity, and no intuitive or instinctive sense for detecting deceit. The positive convictions that many have along the lines of "I can always tell when I am lied to", or "I know it when my child is lying to me", are sad self-delusion and cause great harm, either by falsely accusing someone of a lie or by falsely believing that someone is telling the truth (and therefore that another must be lying).
It has been suggested that signs - for instance, showing three fingers to indicate how many glasses of beer one desires to order - are proof that body language does exist and function. However, signs are awarely made and verbal, are language, are therefore not non-verbal. That one uses the body to make them does not turn them into body language! Body language concerns those supposed forms of communication that are unaware, intuitive, instinctive. Not willfully made signs with a clear verbal meaning.