Weekly observations documented developmental changes in mother-infant face-to-face communication between birth and 3 months. Developmental trajectories for each dyad of the duration of infant facial expressions showed a change from the dominance of Simple Attention (without other emotion expressions) to active and emotionally positive forms of attention to the mother toward the end of the 2nd month. The results support an overlapping waves model, rather than a stage model, of developmental change. Sequential analysis found developmental changes from cycling between Gaze Elsewhere and Simple Attention to the Mother's Face in the early weeks to a complex sequence of transitions between Concentrated Attention, Smile, and Cooing Expression nested into sequences of positive communication during the 2nd and 3rd months.

This study documented the growth of the earliest form of face-to-face communication in 16 mother-infant dyads, videotaped weekly during a naturalistic face-to-face interaction, between 1 and 14 weeks, in 2 conditions: with the infant in the mother's arms and with the infant semi-reclined on a sofa. Results showed a curvilinear development of early face-to-face communication, with a significant increase occurring between Week 4 and Week 9 depending on the dyad. After 2 months, trajectories diverged into 2 groups: I whose duration of face-to-face communication continued to increase and I whose duration peaked and then began to decrease. After the 1st month, the duration of face-to-face communication was significantly longer when the infant was on the sofa rather than in the mother's arms. In the latter condition, during the 3rd month, girls spent a significantly longer time than boys in face-to-face communication. These findings suggest that context (infant being held vs. not being held) interacts with the infant's age and sex in affecting mother-infant communication.

A microgenetic research design with a multiple case study method and a combination of quantitative and qualitative analyses was used to investigate interdyad differences in real-time dynamics and developmental change processes in mother-infant face-to-face communication over the first 3 months of life. Weekly observations of 24 mother-infant dyads with analyses performed dyad by dyad showed that most dyads go through 2 qualitatively different developmental phases of early face-to-face communication: After a phase of mutual attentiveness, mutual engagement begins in Weeks 7-8, with infant smiling and cooing bidirectionally linked with maternal mirroring. This gives rise to sequences of positive feedback that, by the 3rd month, dynamically stabilizes into innovative play routines. However, when there is a lack of bidirectional positive feedback between infant and maternal behaviors, and a lack of permeability of the early communicative patterns to incorporate innovations, the development of the mutual engagement phase is compromised. The findings contribute both to theories of relationship change processes and to clinical work with at-risk mother-infant interactions.

Fathers of preterm infants should receive personalized support specifically addressed to them and based on the infant's gestational age.

The process of change represents a main, central issue for the study of development. Basic and applied researchers in developmental science have aimed their research work at answering several key questions related to the problem of change. How does change occur? What mechanisms produce change? What conditions are likely to promote the emergence of change in development? Another related question concerns the stability versus instability of new behavioral patterns that emerge as a consequence of an intervention. What are the relationships between variability and stability in developmental processes? Does the emergence of new behavioral patterns tend to suppress the old patterns or to coexist with them? Nevertheless, observing and understanding how change occurs has been recognized to be a quite difficult and challenging task (Miller & Coyle, 1999;Siegler & Crowley, 1991). This is despite recent advances in both theoretical perspectives and methods focused on change processes that have brought considerable progress in the research field (see "Microgenetic designs as promising tools," below). Part of the challenge is due to the complexity of conceptualizing change processes. It is our contention, however, that the main problem appears to come from the difficulty of devising and implementing appropriate methods for studying change while it is occurring (Fogel, 1990;Kuhn, 1995;Siegler, 1995), instead of comparing pre-and post-change behavioral patterns.In this chapter, we aim to illustrate a research design, referred to as microgenetic designs, specifically devised for documenting change processes in development. First, we discuss the limitations of traditional research designs to capture ongoing processes of change. We then present microgenetic designs through an illustration of their key characteristics. This is followed by a review of the theoretical foundations of microgenetic designs as well as some of the historical and current observational and experimental