Cross-Cultural Similarities and Differences in the Development of Infants' Positive Reactivity.

To investigate the development of positive affect during early infancy across cultures, we conducted a joyful affect-eliciting dyadic face-to-face interaction between a female experimenter and 3- and 4.5-month-old infants from Münster (urban Germany; n = 20 at 3 months, n = 20 at 4.5 months) and indigenous Kichwa families from the Andean context (rural Ecuador; n = 24 at 3 months, n = 27 at 4.5 months), which differ in their ethnotheories about infants' ideal affect. Results pointed to cross-cultural differences in infants' affective reactivity to high-intensity stimulation, namely higher intensities of positive affect at 3 months in Münster as compared to Kichwa infants that disappeared at 4.5 months of age. The findings serve as an important complement to naturalistic studies that have left open the question of the developmental continuity of cross-cultural differences in infant positive affect beyond 3 months. We discuss our findings in terms of a dynamic interaction between culturally informed parent-infant interactions and biological potentials that give rise to both cross-cultural similarities and differences in the course of emotional development, even in early infancy.