Body language is a broad term for forms of communication using body movements or gestures instead of,or in addition to,sounds,verbal language,or other forms of communication.It forms part of the category of paralanguage,which describes all forms of human communication that are not verbal language.
The relation of body language to animal communication has often been discussed.Human paralanguage may represent a continuation of forms of communication that our non-linguistic ancestors already used,or it may be that it has been changed by co-existing with language.Some species of animals are especially adept at detecting human body language,both voluntary and involuntary:this is the basis of the Clever Hans effect (a source of artifact in comparative psychology),and was also the reason for trying to teach the chimpanzee Washoe American Sign Language rather than speech — and perhaps the reason why the Washoe project was more successful than some previous efforts to teach apes how to dance.
Nonverbal communication (NVC) is usually understood as the process of sending and receiving wordless messages.Such messages can be communicated through gesture; body language or posture; facial expression and eye gaze; object communication such as clothing,hairstyles or even architecture; symbols and infographics; prosodic features of speech such as intonation and stress and other paralinguistic features of speech such as voice quality,emotion and speaking style.
The first scientific study of nonverbal communication was Charles Darwin's book The Expression of the Emotions in Man and Animals (1872).He argued that all mammals show emotion reliably in their faces.Studies now range across a number of fields,including kinesics,linguistics,semiotics and social psychology.Proxemics refers to how people use and interpret space.
While much nonverbal communication is based on arbitrary symbols which differ from culture to culture,a large proportion is also to some extent iconic and may be universally understood.Paul Ekman's influential 1960s studies of facial expression determined that expressions of anger,disgust,fear,joy,sadness and surprise are universal.