A cross-cultural comparison of the development of the social smile: a longitudinal study of maternal and infant imitation in 6- and 12-week-old infants.

Social smiling is universally regarded as being an infant's first facial expression of pleasure. Underlying co-constructivist emotion theories are the assumptions that the emergence of social smiling is bound to experiences of face-to-face interactions with caregivers and the impact of two developmental mechanisms--maternal and infant imitation. We analyzed mother-infant interactions from two different socio-cultural contexts and hypothesized that cross-cultural differences in face-to-face interactions determine the occurrence of both of these mechanisms and of the frequency of social smiling by 12-week-old infants. Twenty mother-infant dyads from a socio-cultural community with many face-to-face interactions (German families, Münster) were compared with 24 mother-infant dyads from a socio-cultural community with few such interactions (rural Nso families, Cameroon) when the infants were aged 6 and 12 weeks. When infants were 6 weeks old, mothers and their infants from both cultural communities smiled at each other for similar (albeit very short) amounts of time and used imitated each other's smiling similarly rarely. In contrast, when infants were 12 weeks old, mothers and their infants from Münster smiled at and imitated each other more often than did Nso mothers and their infants.