As always, the scope and depth of Dr. Sander's excursions into matters of human experience and development are rich and full of wisdom. He challenges us to choose from an extended array of ideas in his work. Writing this commentary, I have selected the ideas that are of greatest use and relevance to my own research in newborn sleep state organization and my work as a clinical psychoanalyst.
In his article in this issue, Sander describes a new way to explore the relationship of the child -caretaker dyad. Replacing the model of development that connects variables in a linear causality, Sander recommends a non-linear dynamical systems perspective; process becomes the focus of study. Studies of development and change lead to general principles about the process as specific developmental phenomena are observed.
An example of the old model of linear cause and effect is a study of newborn infant state organization, which tested the hypothesis that a calm and contingently regulated nursery environment will produce infants with more mature and steadier state organization (Fajardo et al., 1990(Fajardo et al., , 1992)). In a linear model, evaluating state organization was based on an ongoing record over 24 hours of behavior or physiological markers such as REM, muscle tone, heartbeat, respiration, startles, and other body movements. Each state was defined differently with the use of these parameters. State was determined for all infants in the same way, based on the amount of each behavior in every 10-s period. State organization scores were assigned, based on length and/or frequency of each state category. These final scores were used as linear predictors of variables about later developmental outcome. Sander has introduced an alternative nonlinear systems perspective that can be applied to the study of newborn infant state organization. The objective of such a study is not to identify predicting and controlling variables, but to observe conditions in the environmental context and within the infant that co-occur with certain patterns of state organization. From a nonlinear systems perspective, investigators ask different questions, not about prediction, but about how the infant fits together with his or her caretaker and environmental context. Once the how is understood, it is possible to search for developmental continuities and prediction, hypothesizing continuities over time in the changing patterns of fit between infant and her context. This inquiry can be pursued in a linear model, testing hypotheses about predictors of later state patterns, adaptive capacities, and other developmental functioning.
Nearly two decades ago in pioneering work (1980) on newborn state organization, Sander studied the infant -caretaker relationship by describing each infant's uniquely characteristic regulatory patterns in the context of his or her particular and unique caretaking environment.