ABSTRACT
In the last two decades, more and more studies have taken a process perspective and looked at how young children are developing over time. This process approach is dependent on the collection of (many) repeated measurements with the same individuals. However, when we start observing the changes in behavior across time, we are struck by the large differences from measurement to measurement. As Thelen and Smith (1994) have pointed out in their seminal publication, it is important to distinguish stability and variability on two time scales. The first time scale is the “view from above,” where we observe global structure across “developmental time.” For instance, when learning to communicate verbally, infants display roughly the same behaviors. They most often start with expressive vocalizations, and go through a “babbling” stage. The second time scale views development “from below,” and measures the changes that occur from moment to moment. From here, a much more irregular—almost chaotic—picture emerges. In real time, development turns out to be variable and changes from moment to moment. We see, for instance, that not all infants use the same types of vocalizations and that there is large variability in vocalization and communication from day to day. Thus, though development might seem to be ordered at a macroscopic time scale, the microscopic time scales reveals large differences between and within individuals.
