A new look at the very early origins of smiling

Abstract Of all the facial expressions of emotions, smiling has been studied empirically since the birth of psychology and has continued to be a central topic of this discipline until today. The reason for this long-standing interest probably derives from the fact that smiling appears to be one of the most complicated expressions in terms of the conditions that precipitate it, the functions it serves, and the developmental trajectories it depicts. Smiling is, in effect, an expressive behavior that, during development, changes in morphology, in timing, in eliciting contexts, and in function. Its global facial configuration, produced by the contraction of the zygomaticus major muscles, remains from the first few months of life an essential component of nonverbal social communication although its underlying “emotions” or “meanings” undergo extensive developmental and cultural transformations. Smiling is observable as a stable pattern of facial movements present since birth, in term and pre-term neonates. Unlike “social smiling”, that emerges later (at about 2 months of age) and has been analyzed in several early and more recent empirical contributions, little is known about the significance of neonatal smiles or their developmental relevance for later smiling. Neonatal smiling is considered a type of behavior which occurs during sleep in the absence of recognized external or internal (visceral) stimuli. For this reason it is known in literature as reflexive, spontaneous or endogenous smiling. The aim of this chapter is to present recent studies we conducted (Dondi, Costabile, Rabissoni, Gianfranchi, Lombardi, and Corchia, 2004; Dondi, Costabile, Vacca, Franchin, Agnoli, Lombardi, and Corchia, 2008; Dondi, Messinger, Colle, Tabasso, Simion, Dalla Barba, and Fogel, 2007; Messinger, Dondi, Nelson-Goens, Beghi, Fogel, and Simion, 2002) in which, for the first time, the very early origins of smiling in pre-term and full-term neonates were systematically investigated by using anatomically based facial coding techniques, such as FACS (Ekman, Friesen, and Hager, 2002) and Baby FACS (Oster, in press). In particular, contrary to what has been generally reported in literature, we found that Duchenne smiling (a form of smile associated in adults with positive emotional activation) is frequent in full-term and pre-term neonates, and that it is exhibited by infants in all behavioural states examined (even while neonates were awake). Unexpectedly, we found also a frequent and very brief motor activity of the zygomaticus major which has never been described in neonates, and an association between active (REM) sleep and long-lasting Duchenne smiles.