Young Infants' Sensitivity to Social Contingency from Mother and Stranger: Developmental Changes

We investigated whether 1- and 4-month-old infants are sensitive to social contingency from mother and stranger via DV live-replay paradigm. The result indicated that 1-month-old infants could detect mother's non-contingency. Four-month-olds infants might be able to use smile as a social tool to make a stranger's response contingent again. We defined that there are two subdivision components in sensitivity to social contingency such as detection and expectancy. Detection is a basic ability, and expectancy is an ability what infants form to partner's contingency. Development of detection may be earlier than that of expectancy. Those two components are necessary for development of sensitivity to social contingency. Using smile as a social tool is one of applied abilities, and it develops later. We also found that infants' interest in mother and stranger differed in two age groups. One-month-old can only detect mother's unusual responses but not stranger's. By age of 4 months, infants became more sensitive to contingency from strangers because they are interested in strangers more