FACIAL REFLEXES AND THE ONTOGENY OF FACIAL DISPLAYS

This chapter examines facial reflexes and the ontogeny of facial displays. To begin with, the facial reflexes are crucial to any evolutionary account of human facial displays. Normal adult facial physiology includes various reflexes that are generally considered innate and immutable and are characterized by few synapses. These reflexes are generally protective, although some are now mostly vestigial, such as the Hering-Breuer (dive) reflex, which slows the heart when the face is cooled. The facial reflexes are usually divided into three kinds: (1) superficial reflexes, (2) visceral reflexes, and (3) myotatic reflexes. Both the normal and, in infancy, the pathological facial reflexes act to facilitate more complex activities. These actions are very complex and their effects are too broad to be considered typical reflexes, but their stereotypy and inertia make them reflex-like. Many theorists are interested generally in the relations between facial actions and those of the autonomic nervous system (ANS). Adults shape the child's developing displays, and the raw material shaped by this parental pedagogy is the repertoire of preexisting facial reflexes. Subsequently, children may develop mature displays by direct imitation of caretakers who model and prompt for appropriate displays; this mechanism is entirely independent of the form and function of the facial reflexes. Three cases of reflexes and their arguably emancipated counterparts in adult human displays can be proposed: (1) tickling and amusement displays, (2) startle and surprise displays, and (3) gagging and revulsion displays.