Positive Affectivity and Fear Trajectories in Infancy: Contributions of Mother-Child Interaction Factors.

Fear and positive emotionality were considered in a growth modeling context. Mothers, primarily Caucasian (91.9%) and of middle socioeconomic status, participated in play interactions with infants at 4 months (N = 148). Infant fear and positive affectivity were evaluated at 6, 8, 10, and 12 months of age. A linear trajectory was superior in explaining growth for parent report and observation-based indicators of positive affectivity and parent report of fearfulness; a piecewise model explained the nonlinear growth of observation-based fear. Responsiveness in mother-infant interactions emerged as a significant predictor of the fear trajectory, with higher sensitivity predicting lower levels of observed fear. Reciprocity, tempo, emotional tone, and intensity of mother-infant interactions also made significant contributions to temperament development; however, analyses addressing these were exploratory.