Children's Deliberate Control of Facial Action Units Involved in Sad and Happy Expressions

Few attempts have been made since the pioneer work of Ekman et al. (1980) to examine the development of the deliberate control of facial action units in children. We are reporting here two studies concerned with this issue. In Study 1, we investigated children's ability to activate facial action units involved in sadness and happiness expressions as well as combinations of these action units. In Study 2, we examined children's ability to pose happiness and sadness with their face, without telling them which action unit to activate. The children who took part in this study were simply asked to portray happiness and sadness as convincingly as possible. The results of Study 1 indicate a strong developmental progression in children's ability to produce elementary facial components of both emotions as well as in their ability to produce a combination of the elements in the case of happiness. In agreement with prior research in motor development, several non-target action units were also activated when children performed the task. Their occurrence persisted throughout childhood, indicating limitations in the finer motor control achieved by children across age. The results obtained in Study 2 paralleled those obtained in Study 1 in many respects, providing evidence that the children used the technique of deliberate action to pose the two target emotions.