The expressive pattern of laughter

Laughter as a vocal expressive-communicative signal is one of the least understood and most frequently overlooked human behaviors. The chapter provides an overview of what we know about laughter in terms of respiration, vocalization, facial action, and body movement and attempts to illustrate the mechanisms of laughter and to de-fine its elements. The importance of discriminating between spontaneous and con-trived laughter is pointed out and it is argued that unrestrained spontaneous laughter involves inarticulate vocalization. It is argued that we need research integrating the different systems in laughter including experience. Laughter is a conspicuous but frequently overlooked human phenomenon. In ontogenetic development it emerges, later than smiling, around the fourth month; however, cases of gelastic epilepsy (from Greek; gelos = laughter) among neonates demonstrate that all structures are there and functional on date of birth. Further evidence for its innateness comes from twin studies as well as from the fact that laughter is easily observable among deaf-blind children (even among deaf-blin