Ray Birdwhistell was a pioneer in the study of non-verbal communication, best known for developing Kinesics, the scientific study of body motion as a systematic language. His most influential work, often sought in PDF format as El lenguaje de la expresión corporal (originally published in English as Kinesics and Context
La comunicación es multimodal: Los seres humanos utilizan todos los sentidos para comunicarse, y la información visual de los gestos está codificada y sigue patrones culturales específicos.
Stop looking for the "decoder ring" for body language. Start looking for the grammar of motion. That is Birdwhistell’s legacy.