Sentence:  In the early 1950 's , Smith , together with his distinguished colleague , George Trager ( so austerely academic he sometimes fights his own evident charm ) , and a third man with the engaging name of Birdwhistell ( Ray ) , agreed on some basic premises about the three-part process that makes communication : ( 1 ) words or language ( 2 ) paralanguage , a set of phenomena including laughing , weeping , voice breaks , and `` tone '' of voice , and ( 3 ) kinesics , the technical name for gestures , facial expressions , and body shifts - <WSD>nodding</WSD> or shaking the head , `` talking '' with one 's hands , et cetera . 
Meaning of the word marked with <WSD> tags:  lower and raise the head, as to indicate assent or agreement or confirmation