The interplay between language acquisition and cognitive development

Due to limited research on cross-cultural similarities and differences in the development of infant smiling, the main goals of this study were to analyze, first, the development of infants' bouts of intense smiling during their third month and, second, the interactional preludes to infants' affective climax in two cultural contexts, namely Kichwa families from the Ecuadorian Andes region and educated urban middle-class families from Münster, Germany, which differ concerning their cultural models on infant smiling. Based on a longitudinal, naturalistic study design, mother-infant interaction in Kichwa (n = 10) and Münster (n = 10) families was analyzed when infants were 9 and 13 weeks old. Following a mixed methods approach, a quantitative analysis of infant smiling based on a 1-second interval-coding approach showed that there was a significant increase in infants' high-intensity positive affect from 9 to 13 weeks in the Münster, but not the Kichwa sample, leading to significant cross-cultural differences at 13 weeks. Complementarily, the qualitative analysis of the interactional preludes to the 66 infants' affective climaxes at 13 weeks identified two main patterns that characterized the dynamic that resulted in high-intensity positive affect and that were similar across the two cultural contexts: the first was intense and multimodal stimulation with repetition and theme variation, and the second was positively tuned and mutually contingent responsiveness, often in the form of prolonged proto-conversations between mother and infant. Overall, this open approach converged on key mechanisms underlying infant smiling, namely infants' experience of mastery based on effortful assimilation or self-efficacy, which was embedded in episodes of intersubjective coordination. Overall, these results suggest universality without uniformity; that is, similar interactional mechanisms are associated with high-intense positivity in infants, while the episodes are co-constructed differently in different dyads and high-intense positivity varies in significance and frequency across cultures.