Changing patterns of infant behavior and mother-infant interaction:Intra- and interindividual variability

Mother-infant dyads were observed weekly at their homes for a 15-month period. In this way longitudinal data about the infants' crying, fretting/fussing, smiling and different types of physical contact with the mother were collected. The subject of this study concerns the variability and stability in macroscopic patterns of associations between these behaviors. Different types of associations were found between the behaviors, and most of them changed considerably as the infant developed. Individual differences in the nature of the associations and in the changes they underwent over time predominated, but in a limited number of cases the infants shared the same developmental trajectories of behavioral associations. The results show how the use of intensive time series designs can be advantageous in clarifying issues of long-term variability and stability in human behavior. They also support the notion of changing patterns of behavior being a normal feature of early development.